(ii)
EDUCATION AND TRAINING EQUIPMENT
Declaration of Conformity:
Directives (where applicable)
89/392/CEE as amended by 91/368/EEC
89/336/CEE
72/23/CEE
We declarethat the following unit complieswith the aboveEEC directives:
R633 Refrigeration Cycle Demonstration Unit
For and on behalf of
P.A. HILTON LIMITED
4,~;._AA
~
TechnicalDirector
P .A. HILTON LIMITED
HorsebridgeMill, King's Sombome,
Stockbridge,Hampshire,S020 6PX,
England.
Tel No. National Romsey(01794) 388382
International
+44 1794 388382
Fax No. +44 1794388129
E-mail: sales@p-a-hilton.co.uk
(i)
POLICY STATEMENT
After Sales Service
We, P.A Hilton Ltd., attach considerable imJX)rtanCein being able to retain die confi(k;nce and goodwill
of our clients in offering an effective after sales service. Every effort is made to answer clients
COrIesponOODCC
promptly and to JXOvide a rapid follow up of spares and repi.:ement parts by
maintaining comprehensive stocks of COIDJXments
usually available ex-stock.
Shouldour clients encounterany difficulty in ~g
that as a first step dley COIU.:tdle Hilton ~tative
repesentative.write direct to P.A. Hilton LId.
or maintaininga Hilton prodtx;t we would ask
in their country or. in me absenceof a 1<x:a1
In the extreme~ a problem may arisein the operatiooof equipmentwbkh could seriouslydisrupt
a teachingor ~h
~hedule. In suchcircwnstancesrapid advicefrom the man~
is desirable
and we wish our clients to know that HiltoDs' will acceptfrom them a tlansfer chargetelephonecall
from anywherein the wcxld.
We ask our clients to treat d1is service as an emergerx:y service only and to use it sparingly and wisely.
Pleasedo be aWaleof the time diff~
that may exist and. before making a tclelitone call. make
notesof die POblemyou wish to describe. English is a prefen'edlanguage.Our telephonenumberis
"Romsey(01794) 388382" and the felephme is oonnally mannedbetween0800 and 1700 hrs GMr
every day. Advarx:enotice of an impendingfelepixmecall by Fax would be appreciated.
~h productmanufacturedby P.A. Hilton Ltd., is testedunderoperatingconditionsin our permanent
instaUationsbefore~-~!ch. VisitorSto ~mdge
Mill are encouragedto operateand evaluateour
equipmentwith initial guidancefran a Hilton en~.
INDEX
~
SCHEMATIC DIAGRAM
1
VALVE POSITIONS DIAGRAM
2
SYMBOLS AND UNITS
3
INTRODUCTION
4
The Refrigeratiooor Heat Pump Cycle
4
The ValX>urCompressionCycle
4
INSf ALLA nON AND COMMISSIONING
THE mLTON REFRIGERATION CYCLE DEMONSTRATION UNIT:
6
10
Useful Data
10
Specification
11
Description
13
OPERATING PROCEDURE
IS
Nonnal Operation
IS
EvaporationPnx:ess
IS
CondensationProcess
16
Shutting Down the Unit
RefrigerantPumpDown
16
17
Oil Return
11
Air Venting
18
MAINTENANCE:
19
High PressW'e
Cut Out
19
Thennometers
19
Minjanue Cin:uit B~
(MCB)
20
ResidualCunent Circuit Breaker(RCCB)
20
Testing the RCCB
20
20
Checkingfor Leaks
20
Chargingor Rechargingwidt Refrigerant
21
CAPABILITIES OF THE REFRIGERATION CYCLE DEMONSTRATION UNIT:
23
1.
Demonsb'ation of die Vspour Com}Xession Cycle
24
2.
The PressmeTemperatmeRelationship
27
3.
Demonstrationof PumpingOver
30
4.
Demonstrationof Charging
31
s.
Demonsttationof Effect of Air in a RefrigelationSystem
32
6.
Effect of EvaJX)rating and Condensing Temperatures on the Refrigeration Rate
3S
7.
Effect of CompressorPressureRatio OIl SystemPerformance
39
8.
Detenninationof Overall Heat TransferCoefficient
43
9.
Generationof a RefrigerationCycle Diagram
47
10.
Measurementof dIe Effect of ConoonsingTemperatureon Com~r
Power Input 51
OBSERVAllON SHEET (Blank)
53
R141b SATURA nON PRESSURE v TEMPERATURE GRAPH
54
R141bP~SURE-ENTHALPY DIAGRAM
ss
R141b COSHH DATA
S6
WIRING DIAGRAM. R633
58
WIRING
DIAGRAM
- 11O-130V
Transformer
59
APPENDIX:
A. Optional R633A Digital Temper:ature
Indicator
- Fitting
B. Optional R633B Digital Wattmeter- Fitting Instructions
Instructions
61
67
1
of-'
.c
:)
"Qj
~
"II
D
~
+-
~
4)
...
=
0)
it
2
NORMAL OPERATION
r
SHUTDOWN
3
SYMBOLS AND UNITS
Svrnool
Pc
Pressureof Refrigerantin Condenser
kNm-2
P.
Pressureof Refrigerantin Evaporator
tNm-1
me
Water Mass Row
1i1.
Water MassF1owRate through Evaporator
it
Temperatureof Water enteringEvaporattl'
oc
~
Tem~
oc
1,
Temperatureof Water leaving Condenser
~
f,.
Temperatureof Water enteringCondenser
~
ts
Evaporating Tempel8t1n"e
oc
..
Temperaturein Condenser
oc
t,
CompressorDischargeTemperature
oc
Is
CondensedLiquid TemperabJre
oc
u
Overall Heat TransferCoefficient
W m-~K-1
Rate dU'OughCondenser
of WaterleavingEvaporator
Presentationof Numerical Data
In dlis manual, numerical quantities obtained during experiments,etc., are expressedin a nondimensionalmanner. That is, me physical quantity involved hasbeendivided by me units in which it
has beenmeasured.
As an example:
10' pNm-1 .
150
This indicatesthat
or
p = 150 x 10' N m-2
alternatively
p = ISOkN m°2.
. Absolute
pressure
=Gauge reading + aunospheric pressure
4
INTRODUCTION
Tbe Refriaeratk»D or Heat PumD Cycle:
A refrigerator is defined as a m~hine w~
prime function is to remove heat from a low temperature
region. Since energy cannot be deSU'OYed.
die heat Iaken in at a low temperature plus any other eneJ'gy
inJX1tm~t be dissipated to die SUn'()Undings.H the tempezabJreat which die heat is dissipated is high
enough ro be useful, e.g. for SpIM:;e
heating, the ~hine
is then called a heat pump.
By selectivedesignof the componentsthe cycle may be optimisedeidler for heat pump applications
or for refrigeration applications. Indeed unckr certain applicationsboth useful functions may be
performedby one machinewhere circumstancespenniL For example,in a dairy where refrigeration
is requiredfor milk cooling and storageand hot water is requiredfor OOuIeor tank washing.
The aausius Statementof the SecorKILaw of Thennodynamicsstatesthat heat will not passfrom a
cold to a ootter region without the aid of an "externalagency". Thus. a refrigerator will require an
"externalagency",i.e. an input of high gradeerergy, for it to operate.
This energy input may be in me foon of
w<X'k.
cx a heat transferat a high temperature.
The most C<XDmon type of refrigerator or heat pump ~
a WORK INPUT and operates00 die
VAPOUR COMPRESSION CYa.E.
t
The Vapour Compression Cycle
The work input to the Vapom CcmpressionCycle drives a compressorwhich maintainsa k>wpressure
in an EVAPORATOR and a higher pressurein CONDENSER.
The temperatW'eat which a liquid will ev8lX>rate
(or a va[X)urwill coodense)is dependenton die
pressure,thus if a suitablefluid is introducedit will evaporateat a low temperatm'e
in the low pressure
evapora1Or
(taking in heat) and will condenseat a higher remperatW'e
in die high pressurecondenser
(rejectingheat).
The high IXeSStD'e
liquid fomted in the condenser must then be returned to the evaporator at a controlled
rate.
Thus. the simple vapour compressionrefrigerationcycle has four main components.
(1) An evaporatorwhereheatis takenin at a low tempe1'ature
as a liquid evaporatesat a low p-essure.
(2) A compressorwhich usesa work input to redI.K:e
the ~ure
..
pressure
of die vapourbeingtransferred
to die condenser.
in the evaporatorand increasethe
(3) A cOIxienserwhere the high pressurevapourcondenses.rejecting heatto its surroundings.
(4) A flow control device which controls die flow of liquid 00ck to die evaporatorand which brings
about die pressurereduction.
The refrigeratioocycle is most interestingfrom the thennodynamicview poinL It is one of the few
~tical plants which operateson a true thennodynamiccycle and involves
(a) Nucleateboiling and filmwise condensation.
(b) Steadyflow processes,i.e. dn'ottling,compressionand beatexchange.
(c) Row conttOl.
(d) The thermodynamicproperties,i.e. pressure,specifICvolume, temperature,specific enthalpy and
specifICenttOpy,of a pure substanceat all conditionsbetweensub-cooledliquid and super-heated
vapour.
Ald\Oughthe vapourcompressioncycle is simple to thosewho are familiar widt it many studentsfind
great difficulty in visualising and understandingdte eventsoccurring within the various components.
5
With dtis in mind P.A. Hilton Ltd., designeddie RefrigerationCycle DemoosuatiooUnit in which die
major pan of the cycle takesp~ inside glasschambersand can dlereforebe observed.
The unit is a valuable~hing aid for studentsin a widerangeof co~
trainingto first degreeat a Universityor PolyteClmic.
from craft andteChnician
6
IN~ ALLA nON AND COMMISSIONING
Removeme unit from its p.:king caseand carefully examineit for damage.If any is foulKi. notify tile
insurersimmediately.
Standthe unit on a table at a convenientheight aM cl~
adlain.
to an elec1ricalsupply, a water supply and
Do not standthe unit in a positionwhere it will be in strongdirect sunlight for long periods.
This may result in high chamberpressureswith the subsequent
lossof the refrigerant charge
through the safetYvalves.
(i)
The tmit is fitted with two long life fluorescentlampswhich for shippingare ~
In orOOrto fit the lamps the rear panel of the m.:hine must be removed.
separately.
Ensuredlat die m&:hineIS NOT CONNEcrED 10 nIB MAINS ELEC1RICAL SUPPLY and
removedie hexagooalbolts and one Dut secmingdie rear panel Note that die bolts are 8mm
acrossflats and the COn'ectsize spanneris recommended.
The lamp socketsare locatedinternally and are under die two vertical slots in ~ unit panel.
Carefully remove me lamps from their packing ma1erialand imezt diem in me white plastic
socketson the left hand and right hand sidesof me panel. SUR>Ort
the socketsby handas tm
lamps are inserted.
While me rear panel is removed ensure mat die Residual C1DTCOt
CiIcuit Breaker switch situated
on DIN rail the right side of the panel is in die ON positioo. The unit will have been left in d1e
ON position when shipped but transit vibration or shock loading can ~
the switched to jwnp
to me OFF position.
(0)
Connectdie mainswater supply to die water inlet at the rear of die unit using the diagooainylon
reinforcedhose. When facing the rear of the machine the water ~
~ on the extreme left
or thepanel.
It ~ recommendedthat the water supply is red through an isolatingvalve that can be
turned ofTwhenthe unit is not in use.
In older to increasethe stability of the condenser water ftowmeter and evaporator water
flowmeter the conttol valveson thesedevicesare fitted to the dischargeside of the flowmeter.
Henceif externaldamageresultsin the flowmeter tubesbeing brokenan externalisolating valve
will be req~
to stop the flow of water from the unit
(ill)
Connectdie remainingwater coupling at the rear of the panelto a suitabledrain using the dear
plastic pipe provided.
(iv)
220/240V Units
Replacethe rear panel BEFORE connectingthe unit to the mains suWly.
The power supply cable will be foWld emergingfrom die rear panel. Connectdie cable to a
suitable fixed power supply via a fused outlet (for 5 Amps) which canplies with die ~
regulatioos.
Brown cable
LIVE or LINE
Bloocable
NEtn'RAL
EARTHor groond
GreenlY ellow cable
Note that fcx safeoperationthe greenlY
ellow cableshouldbe ~ted
earthingpointthatcomplieswith thelocalregulations.
to a low impedance
7
110/I20V Units
The unit hasan internally fitted transformerwhich is suitablefor input voltagesof between110
and 130 Volts (110 to 130V in 5 volt steps). The integral SUWlyl~ must be coonected10d1e
nearestsuitablevoltage tennina1sand mis can ooly be ~hieved by first removing tIx: rear panel
from the unit. The transfonneris locatedon the right handside of the unit when looking at the
rear of the machine.
Before connection to dte transf<l'D1eJ',die l()Cal mean voltage between Line aOONeulI8l should
be measured. by a competent person, widt a suitable meter. Until dte transfonner hu been
connec~ internally as described below die sUWly leOOSHOULD NOT BE CONNECTED TO
THE LOCAL ELECTRICAL
SUPPLY.
The BROWN cableof die supply 1eOO
is conn~ted to the 130V tenninal of the transformerafter
testingat the factrry. Once the local supply voltagehasbeenmeasureddIe brown cable should
be removed fmn die 130V tem1ina1and should be conn~ted to the nearestlabelled voltage
tCJmjnalon the tramfooner. S~ Figure 3 on Page9.
The Blue cable is alreaIy coonectedto the OV terminal on me b'ansfonner.
The Green/Yellowcable is connectedto die Eard1ternlinal on die ttansfc:lm~.
The rear panel may now be repla::ed.
The externalfree end of die supply Ie.t may now be coonectedto the local elecbical supply.
Connect the cable 10 a suitable fixed power sUWly via a fused outlet (for 10 Amps) which
complies with the local regulations.
Brown cable
Blue cable
GreenlYellow cable
UVECR'LINE
NEU1RAL
EARm CR'ground
Note that for safe operation die GreenlYellow cable should be connectedto a low impedance
earthingpoint that complies with the local regulations.
(v)
The standard instrumentation kit includes five OOCto SOOCthermometers aOOtwo -lOOC U>llOOC
thennometers.
One of the -100c to ll00C dtennometershould be inseJ'tedin the central thennometerJXx:ket
located in the condensertop plate and the other in the compressordischargeJXx:ket~. The
remaining dtermometersshould be insertedin dte evaporator~ plate JXx:ketand the four
identical ev8lX>r8fOr
and conde~ cooling water JXx:ke~at dte ends of the evapora~ and
condensercoils.
It is recommendedthat in order to imlXOvethe resolutionof the thennometersa few drops of
light machineoil is OOded
to ~h thennometerp<x:ket.This will help to improvethennaIcontact
betweenthe thennometersarKIthe pockets.
(vi)
If theinSb'Umentation
upgradehasbeen~
in AppendixA in this manual.
at a laterdatethe fitting of the kit is detailed
(viI) A ~oomatic diagram of the machine COIDJX)nentS
is supplied 00 an A3 (4~m
x 297mm
approximately)sheetand a diagramshowing die valve positionsfor ~ration is suppliedon an
A4 (297mm x 2O8mmapproximately)sheet.
Two L shapedclearp~tic schematicholoorsaresuppliedto contain me diagramsand thesemay
either be suspendedon a cord and hung on a wall adjacentto the unit CX'alternativelyclipped to
the top of the uniL
8
If die djagramsare to be fitted to die panel then it will be ~-!!!-ry
to die ~ of d1epanel.
to fit me four clips suwlied
Auach the 4 spring cli~ to the ~ of 1be.-nel using the 8 self-tapping~WS povided. Note
that 8 small pre-drilled holesexist on the ~ of ~ panelto a:ceIXthe ~ws.
The clips shouldbe fitted wid! the OPEN end king toward the fratt of die panel.
The L shapedclear plastic schematicooldersare dIeDslid underthe spring clips.
In order to utilise the plastk COV~for the unit the L shapedschemabcholdezsmay be removed
and stored under the unit panel
9
1
2
4
3
Amendments
2 MAINS FL TER ADDED
10.9.97 JB
A
B
c
SlFPL y m -130Y SO/60Hz
SEe HA" ~
The ~ier
is req.jred to deliver goods strictly ~cordi-9 to
drowing. Componentinspection is the suppliers responsibiity
R8IIIDveoil sharp edges a~ burrs.
Limits unless otherwise stated
TITLE: 110
MTL:
FIIIISH:
-
Fractions * 1/6"
Decimals * 0.25 mm
130V TRANSFORMERWIRINGDlRGRAM
aAGRAH F~
[Drawnby
P. A. HL TON l TO
JB
[
IDimensions: mm
Checked
by:
@Q
Projection'
Issue: 2
Date:4.3.96 DRG. No.
Scale.
KINGS SOMBORNEHAMPSHIRE
TERttNAL KEY
-
no/rig. 1
ENGLAND
I
633365
10
THE HD..TON REFRIGERAnON CYCLE DEMONSTRAnON UNrr
USEFUL DATA
Condenser:
Wal« coil surf~ area: O.O32m3
E VSDOratOC
Water coil surfacearea: 0.032012
Specific beatcapacity of Wafa'(c,>: 4.18 kJ tg"1 K-1
Refri~erant:
R141b 1,1,-dicbloro-1- flooroetbane
Quantity: approximately800 cm' (awroximately 1 kg)
11
SPECIFICADON
Compreaor
Hennetic type ~pressor
with inlegrall/2 H<X'5eIX>wer
mOtor drawing
aPJX"Oxirnately810 Watts.
The com~
is a single cylinder
reciprocatingtype with a displacementof 17.4 cubic centimetres.
Condenser
Vertical, dlick walled high suengtb glass cylinder widt f1arM ends to
give tension free connection to nickel plated brass end plates with
P.T.F.E. seals. Cooling surface - 9 coils of 6.3 mm dia ~
b1be
through which wala: fk>ws. fitted to Oppel'end plate. Cooling area
0.032 m2. Ball valve at the baseof d1ecoDdena' allows refrigerant
charge to be contained within me condenser for demonstration PUllX>8eS.
Evaporator
Aoo(k';d type
-constnx:tionsimilar to concknserbut widt COppt2'tube
surface specially treated to promote nucleate boiling.
Expansion Valve
Float operatedneedlevalve fitted in condensert.se plate.
Charging Valve
Fitted to base of ev8{XXalor usedto intnxluce or di.:barge refrigeranL
Sight Glass
Fitted in pipe betweenexpansionvalve and evaporator- to show
generation
of vapourbubblesaftertheexpansion
valve.
Oil Return Capillary
Combinedwith integralball valvesto allow oil to be simply reblrlltAito
the compresscxin a conttoUedmanner.
Instruments
(StandardUnit)
Pressure28U2eS
-
- Two
Range -100 to +2S0 kN m"2 gauge.
To indicateevaporatorand condenserpressures.
ThermometerS-Seven
Five, RangeO°C to 50°C x ISOmmlong, glass.
Two, Range-10 to 110°Cx ISOmmlong, glass.
Fitted in masspocketsto iJxIicatewater inlet and outlet tem~wres 81
condenserand at evapora1.«,evaJX>rabon
tem~b1re, condensation
temperatureand compressordischargetemperature.
Row meters. Two
Taperedglasstube type, widt stainlesssteel indicator float, ~h fitted
widt a conb'Olvalve. Range 0 to 50 gramme S.I, To indicate and
conttol water flow rate dtroUghevaporatorand condensercoils.
ODtiOnal UD2T8de Instrumentation:
(Not suppUed unless specifically ordered)
Temperature
Indicator
A multi way digital temperature indicaUX' fitted widt 8 stainless steel
sheathed type K thennocouples to replaw.:e
the 7 standard dJermometers
and to measure in addition the condensed liquid temperature at station
is (see ~hematic diagram). The digital temperablre indicator repI.:es
the blanking plate in dte centre of the standard lIInel and may ~y
be
fitted by the customer or if purchased with dte standard unit can be a
factory fitted option.
Wattmeter
A digilal wa1Uneterdesigned 10 iOOicatcme true IX>werconsumption of
me compressor. The watbneter rep~es me blanking plate in me centre
12
of die StaDdaIdpanel and may easily be fined by the CUSfDm~.or if
purchased widt the standard unit can be a f~tory fitted 0IKia1.
SAFETY
No moving parts.
Intemally mounted relief val~ ~t to 2SOkN m"2 gauge fitted to
cOIxIen= aOOevaporator.
High ~ure
cut out fitted to stop compress<rif condenserpessme
exceOOs
220 kN m"2gauge.
Main switch is a combineddouble pole Ininjat1Jre~t
breakerand
overl<>lMi
cut out
3OmAimbalanceResidualCurrent Circuit Breakerfitted.
~
Consauctedfrom GR.P. - attractivemoonstooewipe clean finish.
DIMENSIONS
Height
Width
Depth
Weight
7romm
7romm
43(knm
ro kg 22OVunits (+lOtg for 110V units)
CAUTION
This wnt ~ ~n specifically designedto opeJ'ateat low pressure00 R141band no other refrigerant
shouldbe chargedinto die systemas damageto the comples.D'<X'oda: ~~ts
will be die resulL
13
DESCRIYnON
(pleaserefer to me schematicdiagramon Page 1)
All COlDJX)nents
are mounted 00 an attractive durable glass reinf<XCedplastic panel.
The evaporatoris a v~
glasscylinder with pla1edmetal end plates. A helical coil of copperwbe
conveyswater mrough a pool of refrigerant in the cylinder. The compressordraws vapour from the
evaporatortherebyredocingpressurein the evaJXJrafnr
and this causesthe refrigerant to boil at a low
temperature. In order to boil, or changephasefroo1a liquid to a Vap)ur, heat is ~
and d1isis
extractedfrom the water passingmrough the coppercoil and to a lesserextent from the surroundings.
As heat bas been extta;ted froo1the water its temperabJre
is reduced.
The com~
is an hermetic type similar to those found in many domestic refrigemta'S. The
com~or
is inside the hermeticallysealedcasingand is directly coupledto an elecbic motor.
VaJX)Urfrom die evaJX)rat(X'is drawn into me compressor casing and then into the CODJK'es8(X'
itself
where its Jl'essure is raised before being discharged to the condenser. Having had work done on me
gas its tem~
is iocreased as well as its pressure.
The cooden.a- is also a vertical gJasscylinder fitted with plated metal end plates, the upper one
supportinga helical coil of tubethroughwhich cooling waterflows. The hot high pressurevapourfrom
the COrDpreSSt)f
cools and condensesas it ttansfersbeat to the cooling water inside the nickel plated
c~
coil As beat is transfenedto the cooling water itS temperatureis increased.
The cooled high pressureliquid collects in die tx>ttomof the con~nser and its level cootroIsa float
operatedex~on
valve. This valve reach~ an equilibrium position and discharg~ refrigerantliquid
back to die ev8iX>ratorat die samerate as it is fonned.
As the warm high pressureliquid passesthrough die valve seatingits presswe~
to that in die
evaporatOrand its temperaturemust fall to the saturationtempemwreat the lower pressure. The fall
of tempemnueis accompaniedby the f(X'Inationof vapour bubblesand thesemay be ~n througha
sight glass fitted in the pipe returning the liquid/vapour mixnIre to the evalX>rator.
On entering the evaJX)rat(X"
the low pressureliquid aOOvaJX}urseparate.the liquid passinginto the
"pool" for re-evaporation.while the vapour mixes with the vaJX}urproducedby the boiling ~tion of
the water coil. The vapour mixture then returns to the compressorto repeatthe cycle.
In the standardunit instrumentationis provided to measure:
(i)
The tem~rature and pressureof die refrigerant vapourin die evaporatorand condenser.
(ii)
The tem~rature of die water entering and leaving die coils in d1eevaporatorand condenser.
(ill)
The water flow rates throughbodi coils.
(iv)
The tem~rature of die oot gas leaving the canpessor.
All temperaturesare measuredon die standardunit using red spirit dlennometers.
An optional digital temperatW'e
upgradekit is availablethat allows measurementof the temperatureof
the condensedliquid te as well as the above list of temperatures.
With the addition of this optional upgradedie completecycle diagrammay be plotted on an R141b
pressure-enthalpy
diagram.
An isolating valve is fitted at the condenseroutlet and this may re cl~ed to ~onstrate a technique
used in refrigeration maintenaocewhere the refrigerant charge is collected and contained in the
conde~ or in most CMesa specialisedliquid receiveradjocentto the condenser.
14
This ~hnique is imJX)rtantin onk:r to demOOSb'ate
how to pevcnt ~ escapeof refrig~t
maintermnce.
during
In common with all refrigeration and heat pump systemsthe unit containsa small amountof oil for
lutxication of ~ CaDpessa. During normaloperation~e oil. in die fOODof mist andoil/refrigerant
~Iution is carried from the compessor to the condenserand ultimately to die evap<J'atorwhere it
collects. In order to return this oil to the com~
casingin a controlledmannera valve at the base
of the evaporalorconnectsan oil return capillary to die suction side of the com~
via a ~nd
valve.
For ~rator safety the refrigerant used ~ a veIy low ~
for a given temperabue(V8IX>Uf
pressureat 2OOCis 0.81 Bar amolute). In addition die unit is fitted with a pres8\D'e
switch to nun off
the C<XDpressa'
if dIe condenser~
exceeds220 kN m-z.
For IMided safety and to allow operation by students, both the coodcosecand eVaJ)(Xatorare fitted with
relief valves mountedinside the instrumentpaneL
In order to vent any air inUoducedinto d1esystemduring demonstrationa t.ll valve is sinJatedon d1e
condensertop plate. This allows air to be ventedvia a pipe to the inside of d1epanel
IS
OPERATING PROCEDURE
(please refer to Figure 1 - SchematicDiagram, and Figme 2 R633 Valve Positionsdiagram)
-
To assiStin unOOrstanding
~ration. item namesand relevant items on the two scoomaticdiagrams
suppliedare refelTedto in bold type in the following sections.For example.Refrigerant Pump Down
on Figure 2 and Condenseror Evaporator etc on Figure 1.
The five baD valves shown on the two schematicdiagramshave beeninsIalled for ~
Figure 2 (Page2) diagramshowsthe four standardvalve combinations.
~
The vent valve on die condenseris namally only openedbriefly to vent air from the systemaId this
is referred to elsewhere.
Note mat when the mrlt is shut down the ball valves should AlL be in the closed positioo. This
preven~ the refrigerantmigrating to the lowest temperaturepart of the systemdue to vapourpressure
effects and in most ~s dtis would be the compressorcasing as this will respondmost rapidly to
variations in ambienttemperature.
Normal Ooeration
To start the unit first turn on the cooling water supply and the mains supply to the unit
Open the valves indicatedin Figme 2 (Page2) for Normal Operation.
11risallowsvapourto be<b'awn
from dIeevaporatorby thecompr~r
returnto theevaporator
from thecondenser.
andfor ~
liquid to
Twn on the watersupply to the unit and adjust the control valveson the evaporator water nowmeter
and condenser water nowmeter to give approximately20-30 gls flow rate.
Turnon themainswitchandthecom~
will stanandthetWointemallampswill light
If the optional temperature indicator is fitted then the display on this will also illuminate.
Evaporation ~e&1
As dIe compressorruns dIe condenserpressurep. will rise and dIe evaporatorpressureP. will fall. If
dIe water supply temperawreis high (aPJK'Oximately
16°Cor more) dIen the boiling oction shouldbe
reOOilyvisible from sev~ points on the submergedeV8p(X'a1or
coil. In order to promoteevalXJrabon
from the coil surfacethe coil has been specially treatedto provide many bubble nucleationsites.
If the water temperanue is low then the ev8lX>ratorpressure will need to reach a lower value and roiling
may occur from single sites on the coil, from me surface of me liquid adjacent to the coiJ/surface
interface or from the -.seplate of the evaporator.
To indoce further evaporationfrom odler sites open the ball valve at the baseof the ev8lX>r8tOf.00
NOT open the charging valve as this will allow air to enter the system.
Opening the ball valve at the baseof die evaporatCl'will causedie oil rewm capillary to becomepart
of the evaporatorand the resulting large increasein heat transfer surface area relative to die small
volwne of liquid in the capillary will result in vapour appearingfrom me baseof die chambec.
This techniqueis also usedwhen completing refrigerant pump down.
During normal opera&n oocenucleationhasbeenKtivaled from otha' sites within the chamberdlen
the ball valve at the baseof the chambermay be closed.
16
Unlessdie supply water temperatureis high men altera1ionof ~ evaIJ<nIOrwater flow rate will have
a relatively small eff~t on die ev8lXJrarDr
pressme.
Howeverif die evaporatorwater flow is twned off completelythen the evaporatorpressurewill reduce
slowly until evaporation OCCID'S
from some other ~
smfa::e using beat tI3Dsfmed from die
sunuundings.
CondensadoaProcess
The vapouris dI3wn from the eVaJX)lata'
into the compressorand both ilS pressureand temperatureare
raised. The hot high pressurepassesdtroughthe insuJatedpipe to the condenser.
The temperanueof the p leaving the com~
may be measuredby d1ethermometerin pocket tr.
Note mat if the COOlpreSoD'
is run for long periods widl die coodenserJX'essutehigh then the
temperaturehere can reach SOOC.
As die gaspassesthrough the insulatedpipe therewill be someheat loss and after an initial warming
up period of operatioo this will result in the gas being partially de-supethcated
before it enters the
co~.
In fa:t just after starting,whenthe unit is cold. the gasenteringthe condenserchambermay
evenbe partially condensedand dropletsof liquid, will be seendrippingfrom the top plate.
The gas entering the condemer under n<X'D1al
opezatioowill be in a superheatedcondition and wiD
initially desuperbeatand then condenseon the water cooled coils.
Adjusunent
of thecontrol valveon thecondenser
water nowmeterwill allowthecondc~ ~
to be iocreased or decreased.
To increase the condenser pressure reduce the cooling water now rate.
To reduce the condenserpressure increasethe cooling water now rate.
The condenserpressurewill also be effectedby the inlet temperawreof the cooling water. F<X'the
samewater flow rate the condenserpressurewill be lower if the inlet cooling water temperawreis
lower. The inlet water temperaturewill thereforelimit the minimwn ~hievable coodenserpressure.
As me liquid ex~ds through the float controlledvalve at the baseof the condensersomeevalJ<Xation
of the liquid beginsto occur immediatelydownsueamof d1evalve.
The valve is physically ~hed
to the 00seplate of the condenserand dIereforesome of the heat
requiIedto bring aboutthis phasechangeis ex~ted from die liquid at dIe baseof die condenser.This
has the effect of sulx:oolingdie liquid below the saturationtemperatureassociatedwith the measured
pressureshown on the condenserpressure gauge.
If the optional temperature indicator is fitted then an additional thennocoupleIs is supplied to be
fitted in the baseof the condenserchamber.Heocethe subcooledliquid temperawremay be measured
and this togetherwith the otrer measuredtemperablreS
and p-essuresallows a completerefrigeration
cycle diagramto be plotted on the pressure-eothalpy
diagram ~lied.
The experimentalJl'()CeduIesdelailed elsewhereinvolve operation of the various 00ll valves and
variationof the condenserpressurein or~r to achievevariousoperatingconditions. Thesepl{x:edures
are detailedin the individual experimentalprocedures.
SbuttineDown the Unit
In order to shut down the unit it is recommenOOd
d1a1if die refrigerantchargehasbeenpumpeddown
(transferredto die condenserchamber)then the valve at die baseof the condenseris openedand the
systemallowed to return to a normal rwming condition before the m~hine is fmally shut down.
17
Normal running condition is widl aPJK'Oximately
2o-25mmof liquid in the bottom of the condenser
chamberand dle float valve maintainingthis level constanL
Oncenormal operatingconditionshavebeen~hieved menme main switch shouldbe turnedoff. The
compressorwill stop and me lights on the unit will be extinguished. If the optional temperature
indicator has been fitted the display on this too will be extinguished.
Turn off die cooling water suWly to die unit It is recommendeddlat die (water) control valves are
left open so that if die usersuppliedexternalisolating valve leakswater will be allowed to run to drain
and will be noticed more readily. In addition, if conditionsare suchthat the water supply is likely to
freeze dlen leaving die control valves on the flowmeterSopenmay not prevent die glasstubesbeing
broken but it will makebreakageless likely.
Oncethe unit b$ beenturnedoff then me ball valveson me unit shouldbe closedto mimic me
shutdowncondition. SeeFigure2 (page2).
This will prevent the large volume of refrigerant containedin the evaporcUormigrating into the
compressorcasingdue to vapourpressurechanges.The small volume of liquid in the condensermay
migrate to the compressorunder certain ambientconditionsbut this is no causefor concern.
Refri2erant Pumo Down
This is a procedureoften usedin industrial and commercialrefrigerationpractisewheredie refrigerant
chargeis condensedand collectedeidier in the condenseritself or more commonly in a liquid receiver.
In die RefrigerationCycle DemonstrationUnit R633 die condenserand liquid receiver are combined
in die sameglasscylinder.
In order to carry out pumpingdown dte unit shouldhavebeenoperatingnormally f<X"severalminutes
widt an evaporatorand condensercooling water flow rate of approximately40 gS.l.
By settingthe valvesas shownin me Refrigerant Pump Down diagramin Figure 2 (Page2) me flow
of condensedliquid from the base of me condenseris stoppedand liquid will thereforecontinueto
collect in the condenserchamber.
As liquid b'ansfersfrom the evaporatorthe level will fall and less of the evaporatorcoil surf~e will
be effective in evaporatingthe liquid. The evaporationrate will reduceand the processwill become
slower. This effect may be offset as the liquid level becomesvery low by opening ONLy the ball
valve at the baseof the evaporator.
This will havethe effect of utilising the capiljary surfaceareaand ambientair temperatureto evaporate
additional liquid.
If before pumping down the unit hasbeenoperatedfor a prolongedperiod. the liquid collectedat the
base of the evaporatOrmay appearthicker and less viscous. It may also appearslightly yellow in
colour. The liquid remaining in the evaporatOris primarily the oil d1athas been carried over in the
fOmt of mist and refrigerantoil mixwre from the compressor.
The oil will not evaporate
at me pressures
~bieved by me compressor
and thereforeit mustbe
physicallyreturnedto mecompressor
casing.
Note that me unit should ~
SHUT DOWN when me refrigerant charge is in the PUMP DOWN
condition as under certain ambient conditions it is possible for the charge to migrate to the compressor
casing.
Oil Return (Only when in Pumped Down Condition)
Once the unit has been pumped down as described aoove, the oil may be returned to the compressor
by setting the ball valves to the positions as shown for Oil Return in Figure 2 (page 2). The condenser
18
cooling water aM evaJX)ratorwater flow rates are left as for normal nD1ningand me unit remaim
switched00. The only pam from me evapa-atorto the compressoris via the capillary tube.
The oil in the baseof the evaporatorwill start to flow mrough the capillary blK:t to the com~
casing.
The evaporator chamber may be at low JXeSSureand therefore the oil return process will be slow due
to the low differential pressure. This may be increased and the ~
speeded up if a small amount
of refrigerant liquid is OOmittedto the evalXJ[ator by briefly opening the ball valve at the base of the
condenser. However DO NOT leave this valve open.
Once the oil has beenreturnedto die CODlpresD'casingd1endie ball valves may be ~
position for normal operation as shown in Figm'e2 (page2).
to dx:;
Once die operating coOOiuons have rewrned to noonal and the liquid level in the conde~
is
apJX'Oximately2O-2Smm tOOntOOunit may be eithez shut oown as described ai)Ove or adjusted for
further experiment.
Air Ventin2
A vent valve is siwatedon dle top of the con<knseraIK1this allows air that bas beenadmittedto the
systemto be safely ventedinto the void inside the insb'Umentpanel
Air d1atenters me system usually from the charging valve as part of an experiment will be swept into
the com~
by d1eflow of vapoor from me evaporator and from here to the coodenser where it will
collect around the condenser coils. The air will remain in this area and effectively present an insulating
barrier to vapour ttamfer. condensation and hence heat transfer. The nett result will be a chamber
pressure that is far greater than should be the case for the condensing temperature ~ indicated.
Unl~ demonstratingd1eeffects of air in a coodenserit will be necessaryto vent the air from die
system. The oil utilised in die compresSa'is hygroscopicand air admittedto die systemis likely to
bring widt it water vapour. This should thereforebe ventedfrom die system.
To vent air from the condenser it is necessary 10increase the condenser pressure 10app-oximately 50kN
m-1aboveabnospheric
pressure.
With the unit nmning n<X'Dlally,
cl~ diecontrol valveon thecondenserwater nowmeter.Thiswill
cause die condenser pressure to rise. The time taken to rea;h 5c:k.Nm-1above abnospheric pressure will
depend upon die local ambient temperature and the amount of time that the unit has been running.
Once 5OkNm-1is reachedthe vent valve should be ~
~ned and gas will be heardto enter the
void inside the panel. Close the valve well before the gaugepressurereaches0 kN m-1.
19
MAINTENANCE
Hi2b Pressure Cut Out
At regular intervals and accordingto the local safety regulationsthe high pressurecut out shouldbe
testedas follows:
Start dte unit as detailed for normal operation in the operating procedure 00 Page 15 and
operatewidt a modezatecooling water flow to both dte condenserand evaporaroras detailed.
Allow die unit to warm up and then cl~
the control valve on the condenserwater nowmeter.
This will causethe condenserpressureto rise. At approximately22OkN m"1the compressc.'
shouldbe shutdown by the internal high pressurecut out An audibleclick shouldbe heardfrom
the cut out device.
If the compressordoesnot turn off automaticallyat a oressureof 230kN molthen turn off the
unit at the main switch. It will then be necessaryto adjust the pressure switch as detailed
below.
If the compress<rdoes turn off automatically,~n me control valve on the condenserwater
nowmeter and me condenserpressurewill immediatelyreduce. Once me pressurereducesto
app-oximatelyInN m4 the C<XDpre8s(x'
should automa1ical1y
restan.
Adiusunentof Hiv.h PressureCut out
The following J:roCedure
should only be carried out by a competentpersonand the compressorhigh
pressurecut out must never be set to operate at a pres.ure exceeding220kN m-l (or any reason.
Isolate d1e unit from die mains and remove the rear panel. The high JX'CSSuIe
cut out is located above
the compressor casing on the internal panel surf~e. The cut out is connected by a coiled copper
capillary tube to the condenser p~ure
gauge.
The cut out hastwo adjustingscrewson its top surfacewhich may be coveredby a plastic cap secured
by a single screw. Removethe plastic top cover and to adjustthe cut out pressureturn the screwwith
the larger range. The cut out devicesare commercialdevicesand the pressureindicatedon the scale
may not matchthe cut out pressureindicatedby the pressuregaugewhich is of much higheraccmacy.
Only b1rnthe screw a small incrementat a time and then retest in order to obtain an estimateof its
effect.
By dlis methodthe cut out pressuremay be ~t to 22OkNm-2.
The smaller range scale usually labelled "DIFF" indicates tOOdifference between me cut out and restart
pressures. This should usually be set at aPIl"Oximately l2OkN m-z in order to ensure that me starting
l()1ki on me com~
is minimised
After adjustmentthe ~
cov« should be replaced.
Tbermometers
Due to the relatively small temperature differences between water inlet and outlet temperabJreS.it is
advisable to calIbrate the thermOOleten by pla:ing diem all in a container of watel'.
All of ~ dtennometersshould be marked in S<XDe
way for identifICationand one ~1eCtedas dte
re.ference.Alternatively, if a known standardis availabledtis should be used.
Stir the water for aIx>I1t2 minutes and record the indicated temperanlres on each of the thennometeJ'S.
This should give a table of small differences from the "reference" thennometer.
20
Th~ differencesmay be added(B'subtlaCtedfrom dJe~
as awropriare.
If greater~uracy is requiredmenthe watermay be gently warmedandmediff~nces notedat ~vera1
temperatures. In d1is case a graph of indk-lt~ against difference should be plotted for ~h
th~omeleJ' .
H the optional temperature indkator hasbeenfitted then d1eaOOve
differa1<:ecalitntion will not be
necessaryas all dJermocouples
are switchedin turn through to the sameiOOicatoruniL
Miniature Cb-cuit Breaker (MCB)
The Main Switch on ~ front of the ~el is an MCB and will cut-out in the event of an ov~ICMld
causedby a shoo circuit 01'a shortto earth. If this shouldcut-out.the unit shouldbe discoonectedfrtxn
the supply and the causeof the overloadinvestigatedby a com~tent ~rson.
Residual Current Circuit Breaker (RCCB)
This is situatedinsidethe paneland will isolatethe unit whenthe incomingandoutgoingcurrentsdiffer
by more than 3OmA,as in a leakageto earth situation.
Testin2 the RCCB
The RCCB shouldbe testedby a competentpersonat intervalsthat comply with the local regulations.
Remove the rear panel and switCh on the mUL
The RCCB will be found on the right hand side of the unit WOOD
looting into the rear of the unit
Pressdie button malked 'Test' or 'T' on die RCCB, but 00 NOT TOUCH ANYTfnNG ELSE INSmE
THE UNIT. The largelever on the RCCB shouldh1IDfrOO1d1eON ('r) to OFF ('0') position
immediatelyand me unit isolatedfrom die supply. If dris ck>es
not OCCm',
die RCCB is faulty and~
to be repaired/repla:edby a qualified electrician.
Return die lever to die ON ('I') ~ition
and the unit should be switchedon again
Repia::e the rear panel.
~
This may be cleaned with a mild detergent and then JX}llshedwith a soft clodt. Abrasive cleaners must
not be used.
The pJasticdust cover provided shouJdbe kept in }X>sitionwhen the unit is not in use
Cbeckinl for Leaks
If a leak in the refrigerant circuit is suspected. e.g. if d1ereis a loss of refrigerant from the system, me
following procedlD'e should be adopted:
(A) If tOOreis refri9.erantin the system:
~e die unit in a WanDplaceuntil its temperaturerea:hes32-3SoC.The pressurethrooghoutdie
systemwill now be aboveabnosphericaJKIdie leak may be loca1edei~ by
(i)
Applying a Sb'Ongsmp or detergentsolution to all joints,
(ill
Using an electronicleak detector.
(B) If there is no refrl2erantin the System:
Pressuriseme systemto SOkN m""wim air by applying a manualpump.e.g. motOrcar tyre ~p.
to me charging valve at me baseof the evaporator. The leak may then be locatedas in A.
21
Cbarg2 or Recharge
Under nonnal conditions me vapour press\U'eof die refrigerant does not reach abnospheric pressure Wltil
die liquid is at a temperatme of approximately 32°C.
In order. merefore.to make charging me unit simpler. the one bip can supplied by P.A. Hilton LId
containsa small amolDltof Niuogen gas in order to raise me internal press\D'eartificially.
Before chargingit is recommendedthat me unit is set up in me following way:
Start die unit as detailed for normal operation in die operating procedure on Page 15 and operate
widl a moderatecooling water flow to bodl die condenserand evaporatoras detailed.
Allow the evaporatorpress1D'e
to reduceand then position the ball valvesfor shutdown condition (see
Figure 2 - Page2) and bJrn off the compressor. Note that if the unit is not chargedand containsair
then it may be necessaryto vent this from the condenservia the vent valve on the condensertop plate.
The unit is now~y
for charging.
The chargecan only be releasedfrom the can by using the brasschargingvalve (VCl7/2) suppliedin
the accessaieskiL
Unscrewdie small brasshexagonalnut from die chargingvalve and screwdiis onto die dtreadon die
top of the can. Screw die rest of the charging valve (VC27fl.) into the straight connector on die
refrigerant chargingline (C45/2), also suppliedin die accessorieskit
Removethe brasscap from the fixed charging valve at the baseof the evaporatoron the R633 uniL
Note that the angled end of the refrigerantchargingline hasa b~ pin in the.centreof the connector.
This end should be connectedto the fixed charging valve on the baseof the evaporatOr.When d1e
connectoris screwedtight the pin depressesthe centreof the fixed charging valve and allows access
to the evaporator.
The can should be inverted and me two componentsof the brasscharging valve should be screwed
togetherby rotating me can. SeeFigure 4, Page22. When the componentsof the chargingvalve are
screwedtogemerme refrigerantwill flow into me chargingline dueto me nittOgenpressurein d1ecan.
Open me ball valve at me baseof me evaJX>rator
and me refrigerantwill flow into the evaporator.
Switchon die writ and d1iswill againreducedie evaporatorpressureand assistdie flow of die
refrigerant into die evaJX)rator.
When the liquid level in the evaporatOris abovethe level of the tOpcoil close the ball valve at the base
of the evaporatOr.
Allow die unit to run under nonna! operatingconditions until die liquid level in die condenserhas
stabilised. Ensurethe liquid level is still abovedie top coil of die evapomtol. If this is not die case
then open the ball valve at die 00seof die evaporatorbriefly until d1erequired level is ~hieved.
Unscrewthe charging line from the can and this will close the valve in the can. The ball valve at die
baseof the evaporatorcan be briefly openedto draw in any liquid remaining in die chargingline.
The chargingprocedureis likely to result in someair enteringthe system. To removethe air follow
the procedurefor Air Venting describedon Page 18.
22
0,. Tr~Can
RMX74/1
-
Figure 4
rn
Bras.C~gi'1g
Valva VC27/2
B
Refrigerant Charging
Line CI.5/2
IN c~~
Valw With Centre
Pin
Angled Comector
With Central Pn
23
CAPABILmESOF THE REFRIGERATION CYCLE DEMONSTRATION UNIT
Demonstration of vaJX)m'compressioo refrigeration or heat pump cycle widt visual observation of
the important ~.
2.
Investigation/demonstmtion of d1esaturation pressure-temperature relationship during evapoIation
and con~nsation.
3.
Demonstration of "plDlping over" or "pumping down" into the condenser.
4.
Demonstrationof charging.
5.
Demonstrationof effect of air in a refrigeration system.
6. Detenninationof effect of evaporatingand condensingtemperamreson me refrigeration rate and
condenserheat output
7. Investigationof die effect of compressorpressureratio on systemperfonnance.
8. Deterntinationof overall heattransferbetweenR141band water in the evaporatorand condenser.
With the addition of the optional temperature indicator:-
9.
Generationof a refrigerationcycle diagram on a pressure-enthalpy
chart.
With the addition of the optionalwattmeter:10. Measurementof me eff~t of condensingtemperatureon compressorpower input.
24
1. DEMONSTRA nON OF VAPOUR COMPRESSION REFRIGERA nON OR REA T PUMP
CYCLE
The ex~cnt
shouldbegin wid! the unit at rest.havingbeenleft in die shutdown (SeeFigure2, Page
2) condition for sometime in order for all of the compo~nu to be at a similar ambienttempelabD'e.
Open the ball valveson the cylinders as for normal operation (SeeFigure 2, Page2) but do oot bIrD
on die unit and do not bIrD on die water supply to the evaporatorand condensercoils.
The stu<kntsshouldnOtCthat all of die systemremperaUJreS
and pressmesare "awroximately similar"
(assumingmat d!e unit has DOtbeen left standingin mght swilight and that d!ere is liquid visible in
bod! the conde~ and evaporator).
Turnon theunit andwatersuppliesasootailedfor norrna1
~on
00 Page15.
(i)
Note mat as the com~
draws vapour from me evaporaror the ~
in me evapora1m'faDs.
Similarly as the V8lX>uris compressed by the comiX'CSD' and Imssedto me COIKJen=-die ~
in me condenser rises.
(ii)
As the pressurein the evaporaUX'
falls the liquid will begin to boil due to the reducOO
pressure.
The boiling actim is the refrigerantchangingfrom its liquid phasethrough to a V81X>1D"
~.
Referenceshouldbe madeto the PressureEnthalpydiagramon Page55 or the largee~uJaIed
diagram(C57/10) suppliedin the accessorieskit
In order to changephaseat constantlX'e8Sure,
energyis required to increasethe endlalpy of me
vaJX>ur.This energy is takenfrom the water passingthroughthe evaP<X8fOr
coil and. depending
uJX>n
the water inlet tem~rature and the local ambienttem~rabJre,the surroW1ding
atmospbete.
If the water supply temperatureis high (awroximately 16OCor m<Xe)dlen the roiling ~tion
should be reOOilyvisible from severalpoin~ on the submergedevaporatorcoil. In order to
promoteev8IXJrationfrom the coil surf~e the coil bas been specially treatedto provide many
bubble nucleationsites.
If the water temperawreis low then the evaporatorpressurewill needto reacha lower va1~ and
boiling may occur from single sites on the coil, from die surf~ of the liquid adjacentto die
coil/surfaceinterfaceor from the baseplateof die evaporator.
To indoce funher evaporationfrom other sitesopen the ball valve at the 00seof the evapcntDr.
DO NOT open the charging valve as this will allow air to enter the system.
Openingthe ball valve at the baseof the evaJX)rator
will causethe oil rewm capillary to become
part of die evaporatorand the resulting large iocreasein heatttansfersurfacearearelative to die
small volume of liquid in the capillary will result in vapour ~g
from the base of die
chamber.
If the capillary bJbeis touchedunder theseoperatingconditionsthen the smfacewill feel cold.
WOOnthe v8lK>urbubbles are being prodtx;edfrom me evaporaUX'coil within the evaporator
chamberthen heat is being exb'Xted from me cooling water flowing through the coil. If the
evaporatorinlet water tempelabJretl is examinedafter several minutes operation and this is
comparedwith the water dischargetemperature~ the dischargetemperatm'eshould be fouOOto
be slighdy lower than the inlet tem~.
In <X'derto increasethe apparent temperabJre
difference,the evaporatorwater flow rate may be reduced.
If die evaporatOr cooling water flow rare is ~
completely then it is likely that roiling from
die water coil will stop and die evaporator pressW'Cwill reduce ftn'ther until anothez soun:e of heat
is found. This is most likely to be the base plate as heat is conducroo from the outside air. In
25
addition, dependingupon me local ambient conditions,water vapour will also condenseon die
outside surfaceof me glasscylinder and baseplate. The changein phaseof me water vapourto
a liquid will in itself IX'Oviooheat to causeevaporationof die refrigerant in me chamber.
In addition, if the evaporatorcooling water flow is stoppedthen the rate of condensationfonning
on the condensercoils will also reducedue to me reducedvapourgenerationrate in the evaporataand me reducedvolumettic efficiency of the compressorand increasein specific volume of me
vapour generatedin the evaporatorchamberat low pressure.
(ill) With the evaporatorand condenserwater again flowing as describedin the normal operation
conditions on Page 15 the condenserpressureshouldbe observed.
The condenserpressmewill be seento be higher than that of the evaporator. This is obviously
due to the compressor. The ratio of condenserpressureto evaporatorpressure.PJP.. is known
as the compressorPressureRatio. This will vary ID1derdifferent operating conditions and may
be investigated.
After the W1ithas been nmning for several minutes under nonna! conditions the condenser cooling
water inlet temperabD'eand the discharge temperawre should be compared.
It will be found that the dischargetemperature1, is greaterthan the inlet temperaturer..
This is due to the heat given up by the hot high pressuregas entering the condenserfrom die
compress<X".
Dependingupon operatingconditioosand die length of time the unit hasbeenoperating,the gas
enteringthecondensermay be in a superheated
condition. (Referto the pressureenthalpydiagram
on Page55 m'the encapsulateddiagram (C57/10)suppliedin the accessorieskit).
If in the superheated
condition, initially the gaswill desuperheat
and its temperaturewill reachthe
saturation temperaturecorrespondingto the chamberpressme. At this point the vapour will
condenseonto the water cooled coil and this will drip down to the baseof the chamber.
It is die cooling and condensingphasechangethat suppliesthe heat to raise the cooling water
temperature.
If the chamberis at a temperatlD'e
abovethat of the swroundingatmospherethen an unquantified
amountof heatwill be given up to the atmosphere.Howeverthis should be small relative to the
heat given to the cooling water.
(iv) If the condensercooling water flow rate is reducedthen the condenserpressurewill rise rapidly
relative to the time taken for the evaporatorpressureto reducewhen the evaporatorwater supply
was tlD'nedoff.
It will also be noted mat the meantemperatureof the vapour in the condenser~ will also rise.
If the temperarurepocketprotruding into the chamberis condensingvapour men the temperawre
recordedat this point should correspondto the saturationtemperatmeof the refrigenmt at me
indicatedpressure.Note d1atthe indicatedpressureis gaugepressure and the pressuresreferred
to on thepressure..enthalpy
diagramsareabsolutepressures.
In order to allow the dtermometerpocket and thennometerto reacha representativetemperattlre
it will be necessaryto hold the pressureconstantfor a brief period after eachrise in condenser
pressure.
(v) The high pressureliquid leavesthe condenserthrough the expansion valve which is conb'Olled
by a simple float at the baseof the condenser.
26
As soonas the liquid passesthroughthe expansionvalve iU pressuredropsto awroximately the
pressIU'e
inside the eV8lXX8fOr.This ~
me liquid to immediaIelystart to changephasefrom
liquid to V81XXJr.As in the evaporatm'cragy is requiredto bring about me phasechangeand
someof this is taken from the baseplate of the condensera the expansionvalve is ~hcd to
the hue plate.
ExtrlK:tingbeatfrom me baseplateredIx:esits te~
and this in bIrDreducesthe tem~nue
of the condenserliquid at me baseof the condenser.This resultsin ~ liquid being "sub cooled"
below its satUIationtempelatm'e.
If the optional temperature indicator is fitled ~
an IKiditional thennocouple r. is supplied to
be fitled in the base of the colxleDSQ"chamber. Hence the sub cooled liquid tem~
may be
measured and this together with the other measured remperattlreSand pressures allows a complete
refrigeration cycle diagram to be plotted on the pfeSSW'C-enthalpydiagram supplied.
In the condensertrerefore the refrigerantchangesfrom superheatedvapouron entry. through to
sanuatedvapourthen to sabJratedliquid and ultimately to sub cooJedliquid before it leavesthe
condenserchamber.
As ~ refrigezant~
along the pipe leaiing from the exlBn8ioovalve to the eValJ(Xator
beat
will be exb'.:ted from the SUn'Oundings
and ~ liquid will be further convertedto a v8fX)Ur.The
si,ht ,-
just beforeenb'yto theevaporator
allowstheliquid/vaJX)ur
mixtureto be ~ed.
27
2.. PRESSURE TEMPERATURE RELATIONSHIP
The relationshipbetweensanuationpressureand temperaturemay be observedin both me evaporator
and condenser. However as variation in the evaporatingtemperat1D'e
is small for aU but extreme
changesin cooling water flow me condenserIX"Ovides
a moregraphicillustration.
As the conoonser contains refrigeJ'ant in all stages from superheatedvapour through to sub cooled liquid
the dlermometer pocket ~ only records temperatures close to saturation when die pocket is showing
signs of condensed liquid Therefore it is recommended that die pressure temperature relationship in
the condenser is investigated as the condenser pressure increases.
If the pressuretempemturerelationshipis investigatedby reducing the condenserpressurethen the ft
thennometerpocket will be at a tempenuurethat is higher than the surroundingvapour due to its
thermalinertia. Thereforeno vapour will condenseon the pocketand an inCOIreCt
temperaturewill be
measured.
Note that dJepressures referred to on dJepressure-enthalpy chart and on the p-essure-temperaturechart
on Page 29 are "absolute" values.
Absolute pressure = Pressure gauge value + Local abnospheric pressure
Procedure:
(i)
Start the unit for normal operation as shown on Page 15 but iocrease the condenser cooling water
flow to the flowmeter maximum (50 g S.l). The pressure at which the condenser stabilises will
depend upon the water inlet temperawre.
(ii)
Allow die unit to run for approximately IS minutes in order to reach a uniform operating
temperature. Then record die condenserpressmePc, evaporatorpressurePe' die condensing
temperature~ and die evaporatingtemperaturer,.
(ill) ReducedIe cooling water flow by a small incrementso that dIe condenserpressureincreaseby
approximately10-2CBcN
m-z. This amountwill vary depending
upon dIe coolingwaterinlet
temperature.
Allow the unit to stabilisefor a few minutesand againrecord the aboveparameters.
(iv) Re~ the procedureup to the maximumcondenserJX'eSSure
requiredor to the high pressurecut
out value of 22OkNm4
Typical resultsare shown in the table below.
Local Aunospheric~:
lOlkN mol
Condenser
Pressure
Pc I kN m-1 gauge
CondenserPressure
Pc I kN m-1-absolute
Condensing
temperature
E vaporatol' Pressure
E vaporata Pressure
Evaporating
temperature
../~
P.I kN
m°7.
gauge
PG I kN m4 absolute
.,/OC
-41
-31
-21
-11
+4
+49
~
70
80
90
105
150
15.0 19.5
24.0
27.0
31.0
41.0
-68
-69
-69
-69
-69
-69
33
32
32
32
32
32
6.S
4.0
4~
4.0
4.0
4.0
28
Note that tem~
have been estimatedto d1enearestO.soC~ing die SIaOOard
1benDOIDC1m
SUWIied. Whezcthe opdoul temperature indicator is fitted ~~
may be ~
to d1e
nearestO.loC.
The resultsare ploUCdin graphicalfonn on Page29.
Note that the standardJD'eSSUIe
gauge~y
of tl % of gaugefull ..::a)ehasbeat shown as 00Ued
lines abouta mean. The absolute.:curacy of the dlermometers(m-~(XIa} tem~
iDd-k.J1O!'
and
thmnocouples)plus readingerrorswill also .sd to any disc~ies.
8
(f)
.
~
0
0
N
1
ffit
r~
~
N
_f3
III
.1.~
~
~
~
0
0
.l.,~T
~
UO!:J8.1D.:J8S
0
Ll)
t_W N}( I a.lDssa.ld
f5
0
0
to..
g
~
0
~
tV)
a
0
N
0
~
0
29
30
3.
DEMONSTRAnON OF "PUMPING OVER" OR "PUMPING DOWN" INTO mE
CONDENSER
Duringmaintenance
of refrigemOOopJaob.partkularly when repl-=ementof com~nb
is involved.
it is convenient to transf~ the ~gerant to me conck.nser.This ba the ~vantage of saving me
refrigerantfor f1D1heruse and also may avoid the needof ev~ua1ionprior to rechargink.
In addition.for ecologicalreasons
followingme guidelinesof d1eMontreal~l.
refrigerantis in manycountriesoowa criminaloffence.
~ ventingof
This is a proc.edureoften used in indusbial and commercialrefrigeration~tise where the entire
refrigerant charge is condensedand collected either in die corKlenseritself or more commooiy in a
liquid receiverco~ted to the condenser.Once the chargebas beenplrDped into the condenseror
liquid receiverthenwork may be carriedout on the systemwidiout losinglargequantitiesof refrigerant
to atmosphere.For ecological~
following die guidelinesof die Montteal Protorol, the venting
of refrigerantis in many countriesnow a criminal offence.
In the RefrigerationCycle Demonsb'81ion
Unit R633 d1ecoOOe~ and liquid receiver are combined
in d1esameglass cylinder.
In order to carry out pumpingdown, dIe unit should havebeenoperatingnormally for ~veral minutes
widt an evaporatorand condensercooling water flow rate of approximately40 gS.I.
By setting me ball valves as shown in me Refrigerant Pump Down mode (~
flow of condensedliquid from the expansionvalveat the ~
will thereforecontinue to colle(:t in me condenserchamber.
Fig1De 2
of the conoonSel:
is ~
- Page2), me
and liquid
As liquid ttansfecsfrom the evapcnror, the level will fall and lessof the evaporaur coil surf~ will
be effective in evaporalingthe liquid. The evaporatioorate will reduceand die processwill become
slower. This effect may be offset as the liquid level becomesvery low by opening(ONLY) the baD
valve at the baseof the evaporaU>r.
This will have the effect of utilising die capillary surface area and ambient air temperawre to eVa(X)rate
additiona1liquid.
If, beforepumping down, the unit basbeenoperatedfor a prolmged period, die liquid collectedat d1e
baseof the evaporaUX'may appearthicker and less viscoos. It may also appearslightly yellow in
colour. The liquid remaining in die eva!X)ratoris primarily the oil d1athas been carried over in die
form of mist and refrigerantoil mixture from the com~.
The oil will not evaporateat die pessures .:hieved by d1ecanpressor and tOOreforeit must be
physically rewmed to die compressorcasing.
Note that the unit should ~
SHUT DOWN when the refrigerant charge is in the PUMP DOWN
condition as under certain ambient conditions it is possible for die charge to migrate to the compreS&:Jr
casing.
~:
In an industrial plant, isolating valves are usually fitted between all major components. As ~
as the refrigerant has been b'ansferred to the condenser (or liquid receiver) the valves may be
closed. trapping the liquid. The defective comlX>nentcan dIeDbe serviced or repJ.lK:edwid¥>Ut
losing the refrigerant charge.
At me end of the demonsb'8tionthe opportunitymay be takento reblrn the oil collectedin the baseof
me evaporatorto die condenser.The procedurefor this is given underOil Return on Page 17.
However,if oil is not to be returnedto the compressorat this stage,~ mIl valves should be set for
normal operation (SeeFigwe 2, Page2) and me refrigerantallowed to rewrn to the evaporator.
31
4.
DEMONSTRATION OF CHARGING
Due to die restrictionsof die Montreal Protocol it is not recommendedd1atthe refrigerant chargeis
removed from the machinefor any ~n
other than essentialrepair.
If chargeremoval is necessaryd1enrechargingmay be "demonstrated"if convenientto 00 so.
Chargingfrom a Hilton suppliedone nip can should follow the Chargingor RechargingjX'OCedure
on
Page21.
Note that any refrigerantremovedfrom the machineshouldbe storedin a screw topped metal can to
preventevaporationand to stop moistme being absorbedby the oil in solution.
Any refrigerantstoredin sucha can may be drawn ~k into the evaporatorby connectingthe charging
line to the charging valve in a similar way to the standardchargingprocedurebut then immersingthe
open end in the liquid inside the container. If the unit is turned on for normal operation then the
pressuredrop in the evaporatorwill causethe refrigerant to flow into the evaporator. Note that air is
likely to needventing from the condenser.
32
s.
DEMONSTRA nON OF mE EFFECT OF AIR IN A REFRIGERA nON SYSTEM
When air is presentin a refrig~oo plant. it will O(X'Inallybe sweptfrom the evaporata by me flow
of refrigerant vapourand will becomettappedin the con(k;D.W'.
For a combinationof reasons.the air will ~
the com~
delivery IX'CSSIJre
to rise. reducingdie
coefficient of peifonnance.arxl increasingthe power input for a given duty.
The ilx:reaseof pressureis due to
(i)
The total pressure in the coodensu is approximately equal to die sum of the refrigeJ'aDtsatumtion
pressure~ the pressure of die air Jl'CseDt(Dalton's Law of partial pressures).
and
(ii) The air tendsto be swept towards die heat transfersurfaces.fonning an insuJatinglayer which
reduces~ heat b'ansfercoefficient. This in Ulm drives up die temperaturedifferencerequjred
for a given heat transferrate and this results in a higher refrigerant sabJratiootemperatureand
pressure.
The effect of air in the systemmay be demonsttatedas follows:
Procedure:
(i)
Start the unit for normal operation and adjust the evaJX)ratorcooling water flow rate so dlat the
evaporator pressure is below abnospheric pressure. Unless the cooling water temperablre is v«y
high this is likely to be the case in all conditions.
Ensure that the unit is free of air and if o«.essary follow the air vendng procedtDe shown 00 Page
18.
(ii)
Run the lmit for ~veral minutesin order to reachnormal operatingtemperattD'es
men record all
systemtemperatures,pessures and flow rates. Also visually note the condensationrate on me
corKlensercooling coils.
(ill) Connectthe angl~ endof the charginglire (C45/2)suppliedin the~es
valve at the baseof the evaporator.
kit to the charging
(iv) Observe ~ evapc:ntor pressuregauge and ~
open the ball valve at the base of me
evaporator. The evaporatorpressuregaugewill indicate an increasein JXessurefollowed by a
return to its original value.
The condenserpressuregauge,however,will increaseand remain at the new value.
(v) Re~ openingof d1eball valve until the condenserJXessure
hasapproximatelydoubledfrom its
original val~. Note that if the condenserpesswe ~~
22OkNmo1then me high presswecut
out will operateand the experimentwill have to be repeatedfran an air free conditioo.
When air is admitted 10 the evaj)(X'a1Orit initially adds 10 the pressure within the evaporator ~cording
10 Daltoo's Law. However it is almost immediately swept dlrough into die comlX'eSSOfby the flow of
refrigezant v8lX>ur. The mixbD'e then passesdlrougb 10 the comJX'CSSOr
am ultimately to die condenser
where it can go no further d~ to the liquid at die base of the condenser.
In addition. the conlinuous flow of refrigerant vapoW' towards the condenser cooling coil causes die air
to remain around the coil region. The reduced rate of cooOOnsationshould be observed as well as die
increase in condenser pressure.
Record aU system temperatures. pessures and flow rates.
Typical resultsare shown in the following table.
33
Local AtmosphericPressure:lOlkN m-1
TestNo.
1 Air Free
1.With Air
Evaporala GaugePressure
p ~ I kN mo2
-69
-66
Absolute EvaporatorPressure
p ~ I kN mo2
32
35'
t,/OC
400
5.5
EvaporatorwateJ'flow
m.1 g S.l
20.0
20.0
Evapora1fX water inlet
~/OC
11.0
11.0
Evapora1(X'water outlet
~/OC
9.5
10.0
Evaporatingtemperature
Condenser Gauge Pressure
Po 1kN
m-2
-21
59
Absolute Condenser Pressure
Pol kN m-2
80
160
25.5
30.5
4.0
4.0
CondensingTemperature
Condenserwater flow
r./OC
IDa 1 g
S.l
Condenserwater inlet
t./OC
12.0
12.0
Condenserwater outlet
t,/OC
22.0
20.3
The results are plotted on a temperabJre-pressuregraph on Page 34.
»
:-.
=
=:
2'
.,
00
»
~
2'
.,
tD
~
tD
a
"=
tD
.,
~
34
0
~
m-2
CN
8
~
~
..,
~
Q)
CD
:AJ
-
CD
~
Q)
~
(Q
~
0
~
-.
0W
W..,
(") :AJ
Q) ..
-~
CD ..
-n"C
c
-n
=0
I
~
..(J)
~ o~ -.
~O'.
+ 0
0
'<
..,
>-,
(")
c:
(")
(Q"C
CD CD
<
G)-I
Q) CD
c: 3
CD
c:
..,
CD
(J)
(J)
""D
35
6.
EFFECT OF EVAPORATING AND CONDENSING TEMPERA~
REFRIGERAnON RATE AND CONDENSERREAT OUTPUT
ON THE
The effect of evaporatingtemperatmeon die refrigeration rate can be investigated.but due to d1e
limited effect on evaporatingtemperatureof all but very largechangesin cooling waterflow it is more
graphic to investigatecondensingtemperaturefirst.
If time pennits. the correspondingeffects of evaporatingtemperaturemay then be investigated.
The effect of increasingme condensingtemperatureon many refrigeration systemsand heatpwnps is
a reduction in me heat dischargedfrom me condenserand in many casesa smaller reduction in the
refrigerating effect at the evaporator.
Similar reductionswill be observedif the evaporatingtemperatureis lowered
The effocts are due pimarily to the reduction in volwnetric efficiency of the compressorat high
pressureratios (PJPJ and the reduction in specific volume of the refrigerant gas as the evaporating
temperaturereduces.
An investigationof die effectsof pressureratio are given in the following experiment
A simple explanationfor this is that for eachsuctionstrokeof die compressora lower massof gas(for
the samevolume) is drawn in to the cylinder to be compressed.
The effect of increasingcondenserpressuremay be investigatedin the following manner.
Once air free increasethe condensercooling water flow to the flowmeter maximum (50 g S.l).
The pressureat which the condenserstabiliseswill dependupon the water inlet temperature.
(ii)
Set die evaporator water flow to approximately 20-30 g S'l and allow the unit to run for
approx,irnately15-20 minutes. The time taken to stabilisewill dependupon the local ambient
conditions and the cooling water inlet temperature.
(ill) Record all the systemparametersas illustrated in the table on Page36.
(iv) Reduce the condensercooling water flow rate until the condenser pressure increasesby
approximately5-10 kN mo1,Allow the unit to stabiliseand againrecord the parameterson Page
36.
(v) Repeatfor increasingcondenserpressuresto dIe minimum readablevalue on dIe condenserwater
flowmeter is ~bed, or the condenserpressurereaches200 kN roo"gaugepressure.
36
OBSERVA nONS
Local AtmosphericPresswe:lOlkN m-2
Test No.
1
2
:t
4
5
Evaporaux'GaugePressure
Pel kN m-2
-68
-69
-69
-69
-69
AbsoluteEvaporalOr Pressme
Pel kN m-2
33
32
32
32
32
6.5
4.0
4.0
4.0
4.0
20
20
20
20
20
IJ.,O
11.0
11.0
E V8IXX8UX' Temperature
EvaporaUX'Water Row Ra&e
t,/OC
di./ gin S.l
Evapor8tcrWater InJetTemp.
it/OC
11.0
11.0
Evaporat(X'Water Outlet Temp.
ft/1IC
10
10
It)
IG
10
CondensedLiquid Temp.
../IIC
4
Condenser Gauge Pressure
P./ tN m-2-
-41
.31
-21
-II
AbsoluteCondenser Pressure
P./ tN m-2-
60
70
80
90
105
CompressorDischarge
- - Temp.
- -
t,/1IC
Condenser Temperawre
r./OC
15.0
J9.5
24,0
27.0
31.0
m./ gin S*l
50.0
10.0
4.0
2.0
1.0
Condenser W &tel' Flow Rate
CondenserWater Inlet Temp.
r./ac
11.0
11.0
11,0
11.0
11.0
Condenser Water Outlet Temp.
r,/1:C
12.0
16.5
22.0
26.5
31.5
CompressorPowerInput
W/Waus
Note d1a1the temperaturesrecorded have been estimatedto the nearest0.5°C using die standard
thennometerS
supplied. If the optional temperature indicator is fitted with the thermocouplesensors
then the temperaturesmay be recordedto the nearestO.l°C.
37
SPECIMEN CALCULA nONS FOR TFST NO.2
EVAPORATOR
Rate of Heat Transfer to Water in EvaJX)rator:
<J.
=
<J.
=
m. C, (t1 - tz)
20.0 x 10-3x 4.18 x 10' x (11.0 - 10.0)W
Q. =83.6W
-
CONDENSER
Rate of Heat Transferto Water in Condenser:
Qc
= mcc, (" - tJ
Qc = 10.0X 10-3X 4.18 x 103x (12.0 - 11.0)W
Q=222.2W
c
-
DERIVED RESULTS
EvaporatingTemperature
t,/OC
6.5
4.0
4.0
4.0
4.0
CondensingTemperature
~/OC
15.0
19.5
1A.O
27.0
31.0
Heat Transferin Evaporator
Q./W
83.6
83.6
83.6
83.6
83.6
Heat Transfer in Condenser
Oc/W
~
229.9
183.9
129.6
85.7
The graph on Page38 has been drawn from theseresults.
It will be seen that the heat transfer at the condenser decreasesas the condensing temperature increases.
The a1x>vetest may be repeatedat odler evaporatingtemperatures.
~:
In order to expanddie rangeof experimentandto investigatewider variationsin evaporatorand
condensertemperaturesit is possibleto supply WaDDed
water to die wlit. Howeverunlessme
internalpipe connectionsof die unit are modified dlis will havedie effect of supplyingwarmed
water to both the condenserand evaporatorcoils. This will tend to increasebodl condensing
and evaporatingtemperatures.
39
7. ~GA
nON OFTHE EFFECTOF COMPRESSOR
PRESSURE
RAno ON SYSTEM
PERFORMANCE
The effect of increasingthe condensingtemperaturefor a constantgiven evaporatingtemperatureis to
increasethe compressionratio PJP. that the compressoris requiredto deliver.
Due to die effects of valves and die necessarypiston to cylinder bead clearancesdie volumetric
efficiency of reciprocatingcompresSOIS
tendsto fall with increasingpressureratio.
Volumetric efficiency = Actual Volume Delivered
CompressorSwept Volume
In terms of a refrigeration system.
Volumebic efficiency = Mass flow of refris:erantx Soecific volume of refris:erantat inlet
CompressorSwept Volume
Henceif dte volurneb'icefficiency falls widt increasingpressureratio then the effect will be a reduction
in the effective massflow of refrigerant. The massflow of refrigerantthrough the compressorrelates
directly to dte amount condensingon the condensa-coil and this in turn relates to the rate of heat
b'ansferto dte cooling water.
In addition me above equationindicatesme effect of reducing me specific volume of the refrigerant
entering me compressorby lowering me evaporatingtemperature.
The effect of pressure ratio on system performance may be investigated by the following method which
is identical to that used in Experiment 6 on Page 35.
Once air free increase the condenser cooling water flow to the flowmeter maximum (50 g S.l). The
pressure at which the condenser stabilises will depend ulX>nthe water inlet temperature.
(ii)
Setthe evaporatorwater flow to approximately30 g S.land allow the unit to run for approximately
15-20minutes. The time takento stabilisewill dependupon the local ambientconditionsand the
cooling water inlet temperature.
(ill) Record all the systemparametersas illustrated in the table on Page40.
(iv) Reduce the condenser cooling water flow rate until the condenserpressure increasesby
aP{X"Oximately
5-10 kN mol. Allow the unit to stabiliseand againrecord the parameterson Page
40.
(v) Re~ for increasingcondenserpressurestD the minimum readablevalue on the condenserwater
flowmeter is reached,or the condenserpressurereaches200 kN m-zgaugepressure.
40
OBSERVA nONS
Local Atmospheric Preaure: 101 kN m4
Test No.
1
1.
3
4
s
EvapoI31a'GaugePressID'e
Pel tN m-2
-68
-69
-69
-69
-69
Absolute Evaporator Pressure
PeI tN m-2
33
32
32
32
32
6-"'
4.0
4.0
4.0
4.0
20
20
20
20
20
11.0
11.0
EvaponI(X'Tem~
Evapora1aWater Row Rate
t,/OC
Ih. I gin S.l
Evaporaf« Waf.« InJetTemp.
it/OC
11.0
11.0
EvaporalakWater Outlet Temp.
ta/-C
10
10
10
10
10
CondensedLiquid Temp.
re/OC
11,0
Condenser Gauge Pressure
p.1 tN m-2
-41
-31
-21
-11
4
AbsoluteCondensez
~sure
p.1 tN m-2
60
70
8C
90
IOS
15.0
19.5
24.0
27.0
31.0
50.0
10.0
4.0
2.0
1.0
Cu.u~~
Discharge
Temp
CondenserTmnpelabJre
Condenser Watel' Row Rate
r.,/OC
../OC
di./ lID Sol
CondenserWater Inlet Temp
r./OC
11,0
11.0
11.0
11.0
11.0
CondenserWater Outlet Temp
's/OC
12.0
16.5
22.0
26.5
31.5
CompressorPower Input
W I Watts
Note that the temperaturesrecorded have been estimatedto the nearestO.5°C using the standard
thermometerssupplied. If the optional temperature indicator is fitted with the thermocouplesensors
then the tempe~
may be recordedto the nearestO.I°C.
41
SPECIMENCALCULAnONS FOR T~T NO.3
EVAPORATOR
Rate of Heat Transfer to Water in EvaJX)rator:
iii. C, (11- ~
Q. . 20.0X 10-3X 4.18X 10'X (11.0- 10.0)W
Q. = -I3..6W
Q.
=
CONDENSER
Rate of Heat Transfer to Water in Condenser:
Qc
= "c C, (r, - tJ
Qc = 4.0x 10-' x 4.18 x 10' x (12.0 - 11.0)W
Qc =18.3..2W
-
COMP~_SDR
Note that dIe pressmemtio shouldbe derived using Absolutepres8W'e
not GaugePressures.
Delivered PressureRatio
=Pc/P.
32/80
=-2.5
DERIVED RESULTS
CompressorPressmeRatio
p./p.
1.82
2.19
2.5
2.81
3.28
Heat Transfer in Evaporator
Q./W
83.6
83.6
83.6
83.6
83.6
Heat Transfer in Condenser
Q./W
200
229.9
183.9
129.6
85.7
Theseresults are presentedgraphically on Page42.
In order to investigatevolwneuic efficiency it would be necessaryto measurethe rotational speedof
the compress<X'
and to know the mass flow of the refrigerant. With an hermetic compressor
measurementof the compressorrotational speedis not possible.
In order to allow this and odler relatedparametersto be measuredand investigatedP.A. Hilton Ltd can
offer the R713 Refrigeration Laboratory Unit and RC713 Computer Linked Refrigeration
Laboratory Unit.
P.A. Hilton Ltd or their local representative will be pleased to supply information on these and other
available refrigeratiol1/beat pump units.
43
8.
DE~ATlON
OF OVERALL HEAT TRANSFER BETWEEN R141b AND WATER
IN mE EV APORA TOR AND CONDENSER
The Overall Heat TransferCoefficient (U) is die heatttansferrateper unit areaof heatttansfersurface
when a temperaturedifferenceof ooe degreeexists betweendie hot and cold fluids.
In die evaporator,die refrigeranttemperatureis sensiblyconstant,but die water temperaturefalls as it
passesthrough the coils. In die condensersomedegreeof superheating~
be presentwhen the gas
entersthe condenserglasschamber. However the quantity of heat delivered due to the superheating
will be small relative to that attributableto the condensingphasechange. Examination of the high
pressureline of the cycle diagramgeneratedin ExperimentNo.9 on Page47 will confirm this.
In oroor to analysethe overall heatb'aIlSfercoefficient a representativetemperaturedifferencemust be
determinedthat representsthe driving force for heat transferbetweenthe refrigerant and the water.
The temperaturedifferenceto be usedin this caseis the "Logarithmic Mean" which is given by
where9... = Temperawre
differencebetweendie two fluids at inlet,
9..-1ot
= Temperature
differencebetweendie two fluidsat outlet.
and
A dleoreticalanalysisof dle logarithmic meantemperatmedifferencemay be found in mosttext books
on heat transferand will not dlereforebe expandedin dlis manual.
Once air free increasedie condensercooling water flow to a mid range value. The pressureat
which the condenserstabiliseswill dependupon the water inlet temperature.
(ii)
Set the evaporatorwater flow to a mid range value and allow the unit to run for approximately
15-20minutes. The time takento stabilisewill dependupon the local ambientconditionsand the
cooling water inlet temperature.
(ill) Record allllie systemparametersas illustrated in the table on Page44.
44
OBSERVATIONS
Local AUDOspheric
~:
lOlkN m.~
Test No.
1
Evaporata GaugePressure
Pel tN mea
-68
AbsoluteEvaporatorPressure
p.1 kN mea
33
Evaporata'Temperature
EvaporaI« Waf« Flow Rate
t,/OC
die I gin S.l
11.0
EVaporaI«Water Outlet Temp.
'a/OC
10
CondensedLiquid Temp.
"lac
CondenserGaugePressW'e
p.1
tN
m-2
-41
AbsoluteCondenser
~
p.1
tN
m-2
ro
Condenser Tempelature
Condenser Water Flow Rate
5
t,IOC
r-/OC
Ib./ gin 8"1
15.0
so.o
CondenserWaf« Inlet Temp.
~/ac
11.0
CondenserWater Outlet Temp.
r,/OC
12.0
Compressor Power Input
4
20
rs/OC
Discharge
Temp.
-
3
6.5
Evaporata Water Inlet Temp.
Compreso
2.
W I WatU
Note that the tem~rabJres recordedhave been estimatedto me nearest0.5°C using me standard
mennometerssupplied. If the optional temperature indicator is fitted with the themtocouple~nsors
then the temperaturesmay be recordedto the nearestO.I°C.
45
For the Evaoorator
RaICof Heat Transferto Wata' in EvaJX)rator:
Q.
Q.
- t,)
S
IN. C, (t1
S
20.0x 10-' x 4.18x 10' x (11.0- 10.0)W
Q. :.83.6W
e~
- 11.0- 6.5
e~
= 10.0 - 6.5 =
4.5- 3.5
8- .
In~
3.5
~K
Q
U=A&:
u
.
~
83.6'--, W.-2
~~
u =~
For
-
-
the
g-l
w..-2c'
Condenser
Rareof Heat Transf~ to Water in Coode~
Q~
= *~ c, ("
Q~
-
- tJ
50.0x 10-' x 4.18x 10' x (12.0- 11.0)W
Q~ = .
W
8~ . 15.0- 12.0
8--
. 15.0- 12.0 .
8-
.
4.0
-
3.0
ID~
3.0
~K
3.0K
46
Heat Transfer Rate
u=~
A8.
u.
u = ~
Wm-2K-l
47
9. GENERATION OF A REFRIGERATION CYCLE DIAGRAM ON A PRFSSUREENTHALPY CHART
Note this procedure can ONLY be undertaken by the following detailed method with the optional
temperature indicator fitted to the R633 unit as the temperature of the refrigerant liquid in the
condenseris required for one state point on the cycle diagram. However the procedure may be
modified for use with the standard thermometer set. SeePage48.
The fitting JX'OCedUIe
for the optional temperatureIndicator kit, if not already fitted. is given in
Appendix A. Details of the kit are availablefrom P.A. Hilton Ltd. or their local representative.
The vapour compressionrefrigeration cycle is of paramountimportancein tentls of food and drug
preservation,air conditioning, and heatpumps. In order to analysethe systemperformancein tentlS
of die diermodynamiccycle it is common for engineersto record systempressW'eS
and temperawres
and dien to plot the various statepoints on a pressure-enthalpy
chart of the wm'king fluid.
The working fluid in me Hilton RefrigerationCycle DemonstrationUnit SeriesR633 is R141b. This
has me chemicalname 1.1.-Dichloro-l-fluoroed1ane.
A pressure-enthalpy
chart for this substanceis shownon Page55.
A detaileddescriptionof die variousparametersdisplayedand obtainablefrom pressure-endtalpy
charts
will be found in most text books on thermodynamicsand thereforewill not be expandedupon in this
manual.
In order to plot a cycle diagramfor the unit the following procedureshould be adopted.
Procedure:
(i) Start me unit fOf normal operation as shownon Page 15 and ensuredtat me unit is air free by
venting air from the condenseras describedunder air venting on Page 18.
Once air free increasethe condensercooling water flow to a mid range value. The pressureat
which the condenserstabiliseswill dependupon the water inlet temperature.
(ii)
Set the evaporatorwater flow to a mid range value and allow the unit to run for approximately
15-20minutes. The time takento stabilisewill dependupon the local ambientconditionsand the
cooling water inlet temperature.
(ill) Recordall the systemparametersas illustrated in the table on Page49.
(iv) In order to demonsttatethat the cycle variesfor different operatingconditionsit is recommended
that die condenserpressureis variedby adjusbnentof die condensercooling waterflow rate. The
unit should be allowed to stabiliseand die systemparametersrecorded.
The proceduremay also be repeatedat different evaporatingtemperaturesand the resultsplotted
on a pressure-enthalpy
chart as describedbelow.
The results from die following table are shownplotted on PageSO.
The statepoints a. b and c on the diagramon Page50 are locatedin the following manner:(i)
Pointa is at theintersection
of theevaporator
chamber pIeSSm-eP. = 32 kN mozabsolute
andthe
evaporating
temperature Is= 4.0OC.
(ii)
Point b is at the intersectionof the compressorchamberpressurePG= 70 kN
compressor discharge temperature ~ = 41.7OC.
m°2.absolute
and the
48
(ill) Point c is at the inte~tion
condensedliquid tem~
of the compressorchambel'pressurePc= 70 kN m-1~lute
r. = 19.5OC.
and d1e
(iv) The expansionis assumedto be adiabaticand dtereforea ~ of constantenthalpymay be drawn
vertically oown from IK'int c to intersectwidt the evarxratnr presSUIeline Pc.
Consideringthe processesd1a1are happeningat eachSta1epoint in turn:(i)
At JX)inta die v8lX>urfrtm die evaporBt«is drawn into the compe.-,r and me pressureis raised
from P. to Pc. It is evident from die line of constantentropyintersectingwith JX)inta (1.9 kJ kg-I
K-1) that die compession is not isentropic as die pressurerise is completedat an entropy of
aPJXQximately1.92 kJ kg-l K-1. If required the isentropic efficiency of compressionmay be
evaluated.
(ii) The vapour leaving the com~
at point b is superheated
as it is to the right of the saturated
vapour line. The vapoorcools slightly in the pi~ to the condenserand then in the condensertksu~rl1eatingand colxlensingtake p1a;:eat essentiallyconstantpressure.
(ill) At point c me liquid at die baseof me condenseris slightly sub cooled due to me effect of me
cooling water tempembirebeing below the saturationtemperatureof me conde~ chamber
pressure(water tem~
11.6to 16.7OC.Sawrationtemperanueat Pc= 70 kN m-1= 21.7°C).
In addition ~me sub cooling in this unit arrangementis addeddue to the expansionvalve being
physically attachedto the condenserbaseplate. The temperaturedrop causedby me expansion
conductsheat through me baseplatefrom me condensedliquid reducing the liquid temperature
furdler.
(iv) The JXessuredrop causedby me expansionbrings me refrigerantinto the valX>ur!1iquid
mixtm'e
region betweenme saturatedliquid and satlD'8tedvapourlines. The mixture of vapourand liquid
may be seenin the sight glassadj~t to the evaporator.
The liquid/vapom mixbJIemay be seenreturning to the evalJ(X'atOr
through the fitting in the tOp
plate.
Note that mough me experimentmay only be carried out in the aOOvedetail utilising the optional
temperatureindicator. statepoints a and b may be determired using the standardthermometerS.
The temperatureof dIe conOOnsed
liquid may. however.be estimatedfrom dIe saturationpressurein
the condenserif it is assumeddlere is no sub-<:ooling.In dIe aboveexampler.. dIe condensedliquid
tem~.
is measuredas 19.5oC.but dIe saturationtemperawreat 70 kN m-zpressureis 21.7OC.
Cearly somesub-coolinghasoccurred.
49
OBSERVAnONS
Local AttnospbericPressure:lOlkN m-2
1
Test No.
Evaporala GaugePressure
p. I kN m4
-69
Absolute Evaporator Pressure
P. I kN m4
32
Eva{X)ratCKTemperature
ts/OC
Ib.I gill S-l
4.0
Evaporara Water Flow Rate
20
Evapofata Water Inlet Temp
it/OC
11.2
Evaporata'Water Outlet Temp
~/OC
9.7
CondensedLiquid Temp.
../OC
19.5
Condenser
Gauge~
PcI tN m-l
-31
Absolute Condenser Pressure
PcI tN m-l
70
Compressor Discharge Temp.
t.,/OC
41.7
CondenserTemperablre
../OC
19.5
dlc / gin S.l
10.0
CondenserWater Inlet Temp.
r,./OC
11.6
Condenser Water Outlet Temp.
~/OC
16.7
Condenser Water Row Rate
CompressorPower Input
W I Watts
2.
3
4
5
~
!~
Q)
'0
n
=-
CD
13
so
I.A
0
w
w
0
0
t-.)
\.It
0
t-..)
0
0
-
~v.
=0
=-
.
.
-6"
;O ~
_0
~o
=
c..
=.
-6"
'<~
_v.
~o
~~
Vt
0
0
VI
VI
0
0\
0
0
0\
""
0
.,..J
0
0
-.0
i
~
~
0
:...
w
0
0
""
;;'f
'j~
G'
~r"i:t
~
~
~
0
""
0
"0\
§
~
.
0
c.
-V ~:
..~
- ~~
~
-.J
;i
N
..
w
~.:;
l
::r~P
:~
-
-
m
",,~'
~
~
-
'c
'8
~
~
i;:~
9~
..~
~E
1-.»8
~
!
1 ~~
fij-
m
~
~
-t.,)
loA
000
A; ..,°..
l~11
rl"r1
,~
1\
{
~,r\
Oa
-
Co
'oc
INI
~~I.09
00
i.I- ~
.ft
I~
*
"
~
"v-
f\
~
~
't~J
-N
""-0
.
~t
-N
V-O
~
~~
"
\.
i::1:'
~
v
~:'.
-
", 1
1~
'
,\
:~
,\
.. ,
-,
,"
1\
w . V\O\~-0
\
r:
~-:::
.~
'.~
~
I.~
A\
\"
Pressionabsolue/ Absolute pressure(bar)
0
W
\\.:..\
I" \
'i~
0
~
~=-,~,
;If:::to:tt1- ~
-
0
'w
w~
00
1
1I
'-0
---
w
~
0000
~I
\'1
V\O\
~
~
0
0
N
v0
~
0
0
~
v.
0
~
0
0
~
v.
0
u0
0
"'"
"'"
0
0\
\oft
0
51
10. MEASUREMENT OF mE EFFECT OF CONDENSING TEMPERATURE ON
COMPRFSSOR POWER INPUT
Notethis procedurecan~
be undertakenby the followingmethodwith the ootionaldi2ital
wattmeterfitted to the R633unit.
The fitting procedurefor the optional wattmeter kit. if not alreadyfitted, is given in Appendix B.
Details of the kit are availablefrom P.A. Hilton Ltd. or meir local re~tative.
The vapourcompressionrefrigerationcycle is utilised in both refrigerationand heatpump awlications.
In a refrigeration situation the eff~t of high ambienttemperaturewill be to both ~rease the loan on
the refrigeration system(due to heat leakagejntq the cold spacethrough thennal insulation) and to
increasethe condensingtemperaturein order to reject heat from the system.
In a heatpump applicationthe useful heatfrom the condenserwill be more easily utilised for heating
applicationsif rejectedat a high temperature.
In bodl cases,increasingdie condensinglX'Cssureresul~ in a greaterwork requirementfor die
compresscx. In addition, die increased compression ratio will in most cases result in a reduction of
system efficiency due to a reduction in volumetric efficiency. This is due to die necessary clearance
required for compressor valve opening and machining tolerances. At die end of a compression stroke
this clearance value is COOStant
but at high pressure will contain a higher mass of unb'ansferred gas dIaD
at low pressure.
In addition,due to commercialfactors,the motors usedin mostdomesticrefrigerationcompressorswill
be of a relatively low elec1rlcalefficiency. Henceelec1rlcalresistanceheatingeffects in the windings
will be relatively high under all operatingconditions.
Procedure:
(i) Start the unit as for normal operation as shown on Page15 and ensurethat the unit is air free
by venting air from me condenseras describedunder air venting on Page 18.
Once air free increasethe condensercooling water flow to maximum (50 g/s). The pressureat
which the condenserstabiliseswill dependupon the water inlet temperatm'e.
(ii)
Set the evaporatorwater flow to a mid range value and allow me unit to run for awroximately
15-20minutes. The time takento stabilisewill dependuponthe local ambientconditionsand me
cooling water inlet temperature.
(ill) RecorddJecompressorpower input shown OIl the digital wattmeterand the condensingpressure
Pcas illustrated in dJetable on Page52.
(For referenceit is recommendedthat studentscarefully touchthecompressorcasingto experience
the heat loss from die compressordue to electrical heating effects. This representselectrical
energy wasted by the system. Care should be exerc~ed as the comoressor casioa will be
!!QI.)
(iv) Adjust the condensercooling water flow to a lower valueand againallow the systemto stabilise.
Re~
d1eaboveobservations.
(v) The proceduremay be repeatedup to the maximum condensingpressureif local cooling water
conditionspermit
S2
OBSERVAnONS
Local AtmosphericPressure:
kNmo2
Test No.
Evaporala GaugePre~
Pel tN mol
Absolute Evaporator Pressure
Pel tN mol
Evaporata T~penIuIC
E Vaporatm'
Watrl'
Row
Rate
-
EvaporaIO'Waf« Outlet Temp.
~/OC
CondensedLiquid Temp.
"/OC
CondenserGaugePreaure
p./tN
m4
Absolute Condenser Pressure
p./tN
m4
Temp.
-
Condenser T emperahlre
Condenser Water Flow Rate
190
274
302
4
5
",/OC
,,/oc
Ib./ gin S'1
Condenser Water Inlet Temp.
~/OC
CondenserWater Outlet Temp
r,/OC
Compressor
15
3
Ih. I lID 8-1
ts/OC
Discharge
1
"/OC
Evaporara Wat« In1etTemp.
Compressor
-
1
Power Input
W I Watts
Note that the val~ observedwill dependupon the local conditions,the p-essuresset and the local
supply voltage and frequerx:y.
As indicatedabove,the power required to drive the com~
is increased.
increasesas ~ condensingpressme
S3
OBSERVAnONS
Local Atmospheric~:
kNm-7.
1
TestNo.
Evaporata' GaugePressure
Pel kN m-2
Absolute EvaporatorPressme
p.1 kN m-2
Evaporat(X'Temperature
Evapotat(X'Water Flow Rate
.,/OC
m. I gin S-1
EvaporatorWater Inlet Temp.
"/OC
EvaporatorWater Outlet Temp
t,/OC
CondensedLiquid Temp-
r./OC
Condenser Gauge Pressure
p~I kN m-2
Absolute Condenser Pressure
p~I kN m-2
Compres~ DischargeTemp.
t.,/OC
Condenser
Temperawre
~/OC
CondenserWater Flow Rate
Ib.I gin S.1
CondenserWater Inlet Temp
r./OC
CondenserWater Outlet Temp
t,/OC
CompressorPower Input
W / Watts
2
3
4
5
54
rn
~
2'
.,
~
C'.
=
=
--3
tD
a
~
.,
~
2'
~
~
0
0
~
0
(.a)
0
~
tn
0
m
0
...,
0
0
U1
0
~
0
0
Saturation
r-m
,
~
(11
0
1-'.'
m
m-2
~
~
n-{+~
Tl
t1.
n-111
LL
ti
TI
~
a
f1
m
++i
~
~
~
=
z
t
<
=
0
V\
\0
0
'1"\
'1"\
0
0
\I")
0
In
'o:t'
0
0
~
0
~
~
0
0
M
<:>
It"\
N
0
0
N
0
-In
!
-
0000
\CV\
000
\O\t'\
~
~
~
0\;
"#'
0\;
0';
(f'I
N-
o~
\,
011'\
N-
~~
..1
~~
-I
""
...a
l i
I~ !
ill~
~tl
X
'S.J
~
I~
- i
-0 ~ \OV\.qoM
~!
\,
I '.
m
l'
0
~
(.l8q) 3.1ns~.ld
N
~t
- 0 00 0 0
-~~~-
-tv / 3RlosQU'UO!St3Jd
N00
'"
. J~
~;
N-::00
-
0 '55
0
r---
0
V\
\0
0
0
10
0
V\
V\
0
0
'1"\
OJ)
-
~
o~
VI~~
c.
";
.c
=
O~
0~~ .c.
";
.c
-
0=
VI~
~
0
0
('f')
0
V\
N
g
N
-
0
Ir)
S6
SPECIFIC RISKS
. Contact with liquid will causeseverefrost bite
. Decomposesin a fire to give toxic and corrosive fumes
. Containen may bunt if overheated
. Risk of asphyxiation at high concentration
IDENI1F1Ct770N
1.
LI
1.1
SYDOBymS
l,l,-Dichloru-l-O=roethaDe. R-141b
Uses
Plastic fOim blowing aaalt,SOlveDt
2.
COMPOSmON
Substance
Impurida
3.
PHYSIC4LPROPERTIES
At2G-C
liquid
3.1
PbysicalSUte
colo1U': colourless
0d01U': slightly etherial
Tempentura
melting point: -lO3.S-C
boiliDl point: 32.0-C
critical taDper8ture: 20S.C
3.2
(.rubstanCeJor impurities giving a hazard)
1,I ,-dichloro-l-Qooroethane
DOne
~tiOD
~.1Ure:
CAS
EINCS
1717-00-6
404-080-1
Health & Safety
Data Sheet
SOO-C
3.J
pH
DCutr81
3.4
Solubility
in ~
at20.C: 0.54%by weight
in solvCDts:
misciblewith aliphatichydrocarbons.
aromatlcs,ketoaes.chkwiDated
derivatives
a1¥i~
3.5
Vapour pressure
at 2Q8C: 0.81 bar
at SO.C:
3.6
Deasity
(liquid) at 2S.C:
(vlpOur) at 32.C:
5.011
kIfm)
3.7
Other data
criticalpressure: 43.4bar
4.
4.1
STORAGE AND HANDLING
SpedalstoraceaDd
StorebetWeeI1
0- andSO-Cin awell v~rilated~
baDdUac
precaadoDS ~t
storedin.sp«ial1yreinforced
dnDDS.
4.%
PacklDgmaterials
Avoid alloys with 2% or moreof magnesiumor
aluminium.Avoid plastics. Usesteelor polyethyleue
dr1Dns.
4.3
DecompolltioD prvducu
Stableat ambienttemperabl1'e,
but willlDfcrlo thermal
decompositionat elevatedtemper8tures
to give off
hydrochloricand hydrofllWric acidsaDdpossiblypbol8~
4.4
DaQcroas reacdODS
Withnakednameor hot metal~
4.5
lDdJvtduaJpmeDdoD
and pAtecd"e measures
Gloya-
4.6
Sped" protecdve
mcuara
Va1ri1arcthe workiD&area. No aom,.
nama.
4.7
Meuara after IpWqe
0r Ieak8Ie
If in m ~loscd
If this materialis redistributedfor
sale,detailsof its hazardsand
recommendedmethodsof safe
handlingshouldbe passedon to all
users.
.83bIr
1.24.,cm)
loula r=ommeaded
AvoidliquidcoDtKt
HRP Refrigerants Ltd.
Gellibirion Industrial Estate
Pontypridd
Mid Glamorgan
CF37 5SX
withskiD
- eyes
aDd
theiDh8Iati~
of~.
No aaked
-rea. YCDn18le or WaI' tt:1!oCOaIaiDCd
bratbiDI ~
(risk or -.hyxi8lioa/llK)xia).Allow
to eT8pOrIIcor pump into salecoatIiIICr. Prevalt.!rom
mtailla ~
bucmCUISetc.
In caseof emergencytelephone"
01443 842255
57
SPECIFIC RISKS
. Contact with liquid will causeseverefrost bite
. Decomposesin a fire to give toxic and corrosive fumes
. Containers may burst if overheated
. Risk of asphyxiation at high concentration
DestnacttoD of
coDtamiDated coDwDer
...8
4.9
Ret\un to supplia-.
Other recommeDdatioDS Storeat a tanperaturebelow SO-Cin a y~latM
away from all ~~
of heator ignition.
5.
5.1
IGN1110N AND EXPLOSION
F1ash
poiDt
none
5.1
Auto-ignition temperature none
S.J
Special fire or explosioD
hazards
area,
Non-flammableproduct Thermal decompositiongives off
toxic fumesoChydrochloricand hydrofluoric acids and
phosgene.
5.4
Extinction
Not applicable
5.5
Particularmeasura
during OR-fighting
Wear self-containedbreathingapparatusand full acid
resistantprotectiveclothing.
5.,
Other recommendations
Protect.containersfrom heat~urces. Cool with water to
avoid ov« pressurisation.EDsureproductdoesnot come
into contactwith nakedflamesor hot metal surfaces.
6.
TOXlCOLOGICtLINFORMATION
CAS
EINCS
1717-00-6
404-080-1
Health & Safety
Data Sheet
If this materialis redistributedfor
sale,detailsof its hazardsand
recommendedmethodsof safe
handlingshouldbe passedon to all
users.
Employersshouldbe awarethat this productis ~lvent
abusable.
7.
Vapour
2,500 ppm for 30-60minuteswin causevertigo,
drowsinessand respiratoryproblems. May causeincreased
sensitivity of myocardiumabove 12,500ppm.
Uquid
Repeatedandproloaaedskin contactwill produce
dermatosis. Eye contactwill lead to irritation. rednessand
moderateconjunctivitus.
FIRST AID PROCEDURES
Skin contact
Washwith copiousamolmts
ofwater'.
Inhalation
Removeto freshair. ApplyoxygeniCbreathing
is
difficult. Consulta doctor.
EyeCODtact
Wash1!DQ!.~a~ely
with copiousamolmts
of water.
Consult an opbtbalmologist.
8.
SPECIAL PRECt U110NS FOR WASTEDISPOSAL
This matcria1is subj«t to the resttictioasof the
EnvironmentalProt=tiol1 Act and shouldoot be Va1tedto
atmosphere.W.. materialcan be ~
to HRPR.
Movancnt of refri&~
for ~1amation or destIuctioDis
subj~t to the Duty of CareIlK! requiIeIlppropt.ate
documentationCora contro~ Wde.
HRP Refrigerants Ltd.
Gellihirion Industrial Estate
Pontypridd
Mid Glamorgan
CF37 5SX
In caseof emergencytelephone
01443 842255
S9
'3
2
1
4
Amendments
2 MAINS FILTER ADDED
10.9.97 JB
A
NEW 3 CORE POWER CABLE
FROM TRANSFORMERSECONDARY
2'OV TO MA~S FILTER
LENGTH 1000 mm
()
r---
..
j
LINE t )1
-0
HA~
-.
IFLTER
~
~~IP£A~
LOCAl ~PL Y V~ TAGE A~
CON~CT BROWNWIRETO ~AREST
va. TAGE TAPP~ PaNT.
SET TO 130V ~
r-
;
~I
~I
~
HAt-IJFACTURE
1
.
1
i:
1
~:1
m
r-
~
B
I
Q ~o~~~1
<@
(2}1
IllJ--,m
.
@}
1111
@
IW
~I
...1
10
1m
@I
-<I
~.
r-1
i.
.
.
..
1
.
..
~~.~:..
."J.
c
OR~L
3 CORE POWERCABLE
DSC~CT
FROM HAINS FL TER LINE IN
RE ROOTE TO PRt1ARY SIDE
CF TRANSFORMER
~PLY
to -mY
5O/~
SEE MAN WlRNG CMAGRAHFOR TERMNAL KEY
The supplier is reqUred to deliver goods stri:lly accord'W'lgto
dramg. Compcx-.ent
inspection is the suppliers responsibility.
ReIOOveall sharp edges and blSrs.
Limits unless otherwise stated
TITLE:
110
-
130V
TRANSFORMER
--
MTL:
FINISH:
I
DrcwnbY: ..B
Checked
iDimensions mm I °Y
@c::J
Fractions .t 1/6'.
Decimals .t 0.25 mm
Projection:
Issue: 2
WIRING
Dote:4.3.96 DRG. No.
DIRGRAM
Scale.-
no/rig. 1
---
HA~SHIRE ENGLAND
P. A. HLTON LTD KINGSSOMBORNE
633385
61
APPENDIXA
OP'nONAL DIGITAL TEMPERATURE INDICATOR
R633A
If£I-I"iNG
INSTRUcnONS
62
-- --
VjQllK
mQJCator
~l
in the centre of the Wlit.
The addition of the digilal temJ'eraLureindicator not only increases die resolutioo of tem})el3ture
measuremenmfrom to.soC to O.IOC but a thennocouple sensor is provided to record the temlJeJ'a1Ures
of the liquid in the baseof the condenserchamber
The
refrigerant
additiOnal
teJnj)elatures
R141b
allow
PCessure-enthaIpy
a
complete
vapour
re.
comPlession
cycle
diagram
to
be
nrn.i..~_..
-
diagram.
-
Oncethe level has beenmeasuredor marked,position the ball valves for shutdown (SeeFigure 2
R633 Valve Positions)and hJm the unit off. Turn off and disconnectthe unit from the water supply.
Isolate the unit from its electrical supply and then remove the bolts and one nut securing the rear
panel.
Storethe bolts, nut and washersin a containeras thesewill be requiredfor refitting the panel.
Removethe thermometersfrom their pocketsandstorethesesafely. Note that if the original installation
recommendations
were followed dlere will be someoil in ~h of die dlennometerpockets.
With the help of an assistantlay the machineon its back and locatethe 3mm (1/8") diameterblanking
rod in a pipe fitting in the 00seof the condenserchamber. This is the locationfor the 1s thennocouple.
1
63
Ensuremat the liquid level is below the level of the blanking rod and that the condenserpressureis
either at or below atmospheric pressure.
Using a close fitting spannerremovethe nut securingdIe blanking rod.
Take the 0 3mm x 8Smm long diennocouple (!MIS/IO) and using a 0 3mm compressionolive
(PF4/67)and die original nut. insert the diennocouplein die chamberto a depdi JUST BELOW that
of the measuredliquid level.
Rewm me unit to an upright position. Thosewim accessto a vacuumpump may eXb'actany air from
the systemby connectingto me internal pipe leading from me vent valve on top of the condenser
chamber.
Note that the oil in the unit is hygroscopic(absorbswater vapourfrom the air) and the unit shouldDOt
be left open to atmospherefor long periods.
Fit the 7 shon rod type thermocouples(IMlS/l6) in placeof the original thermometers.For the present
time the thermocoupleconnectingleadscan be left ttailing at the front of the panel.
Remove die 92mm x 92mm blank insttument case from the panel by releasing die retaining screws from
inside die machine panel and withdrawing die case from die front of the unit.
The digital temperatw'eindicator and multi way selecta-switch are two separateitems. A separate2
coretbennocouple
cableis suppliedto makemelink betweenmemo
FirSt install the 10 way selector(]MIS/50) at the bottom of the 92mm x 92mm panel orifice. This is
retainedby wire springsandclips whichpressagainstthefascia.Referto FigureA on Page65.
The indicator (!MIS/53) is fitted abovethe multi way selectorand retainedby jacking screwswhich
bear on me rear of the panel fascia. Refer to Figure B on Page65.
Make the 2 core thermocoupleconnectionin accordancewith the wiring diagramon Page71
The Brown or Green (+) wire runs from COMM I to indicator terminal 25 "VI".
The Blue or White (-) wire runs from the terminal on die right of COMM 1 to indicator ternrinal26
"COM",
Apply the label "Oc" to the fa:e of the indicator to the right of the digital display.
Apply the yellow label "TemperattJreIndicator" to the panel fascia.
Electrical Installation
The 3 core IX>wersupply lead for die optional ternperattJre
indicator and separateoptional wawneter
is factory fitted to the following tenninalson the DIN rail connectorson the right handsideof die unit
adjacentto the input IX>werlead. Their free endsare identified ~ follows:
-
49 (Eard1 ColourGreen+ Yellow suipe) FromDIN Rail 5
47 (Line - Colour Red) From DIN Rail 8
48 (NeuU'al Colour Black) From DIN Rail 13
-
~
units already fitted widt a wattmeter (R633B) will use the ~k. of loose JinkssuWlied to tap
into the wattmeterIK>wersupply. Refer to the wiring diagramon Page71.
Unitsnot fitted wim mewattmeterwill useme free wireslabelled47 (Line - Cololn' Red) and 48
(Neub'al- Colour Black) directly.
64
The free end of d1elead will havebeenprotectedwith tenninal covers. Theseshooldbe removedand
the 3 wires given 1 turn throughme ferrite ring suppliedand ~1Ued ooarto the indicator. The red and
b1a;kcablesshooldbe connectedto the following terDlinalson the digital temperatW'e
indicator. Note
that as ~ digital temper8bJre
indicator is double insulated.the green/yellowearth wire is not usedin
this application.
18 L Line renninal securesRed wire 47
17 N Neuttal terminal securesB1a:k wire 48
The themtocoupleleadsmay now be ~red
to the thennocoupletenninalson the multi way switch
oox. Note fran the wiring diagramon Page71 that ~h of the 10 switcOOdchannelcoonectiooson
the rear of the oox has4 terminals. However.in eachcaseonly the left baOO
pair of eachgroup of four
areutilised.
Note that due to a new EuropeanStandard,sometype K d1ennocoupie
w~
insulation and od1ersgreenand white to identify the polarity.
will utilise brown andblue
For ~b tbennocouplethe brown or green~itive lead is connectedto the tenninal marked 1 in ~b
group of four. The blue or white negativelead connectsto me next terminal on the RIGIrr of me
tenninal maIked 1 in eocbgroup of four. The remainingtennina1sin eachgroup of four are not used.
Note that only channelsI to 8 (CHI, CH2, aD...CH8) are utilised. The remainingchannels,9 and
0, are not utilised for dlis option kiL
Start with ~ merm<x:ouple (refer to the schematic diagram) and pass this lead dtrough a convenient hole
in me unit panel (e.g. where me cooling water pipe passes through the panel).
The thennocouplc wires are coloured:
Greenor Browo(+) JX)sitiveto CHI
White or Blue (-) negativeto right band side of CHt
Note that the remaining 2 pairs of thennocouple tenninals, i.e. CH9 and CHO. on the digital temperature
indicata' are useable. Any type K (Nickel-Chrome, Nickel-Aluminium) thermocouple may be conneA:!ed
to these terminals and used in the same manner as those suWlied if other areas of interest exist
NOTE that if local regulations require, or any doubt exists concerning correct connection of the
instrument, the unit should be inspectedby a competent electrician before supplying power to the
unit.
Refit die unit back paneland restoredie elecbical supply and water supply.
Start the unit as for normal operation following the procedureon Page IS and verify that when the
main switch is turnedon the digital temperahlreindicator lights.
The rotary selectorswitch connectsthe indicated thermocouplenumrer to the digital display.
Note that the unconnecteddtennocouplechannelswill give readingsthat have no meaning(full scale
negativeor full scalepositive) unlessa dtennocoupleis flued by dte user.
The digital temperat1D'eindicator has five fmtCtiODkeys on its front fascia. These are used only during
manufocbJre to configure the instrument Pressing me keys may disturb d1e displayed value. The
display will revert to normal after a 60 second delay.
In order to improve dtennal cont.:t widt die thermocoupleprobesit is recommendedthat a small
quantity of light oil is put into eachdtennocouplepockeL
The unit is ~rated in die nonnal way ~rding
to the recommendedlJ:()COOures.
6S
PA~L
FIGURE A
~
USE A SUITABLE FLAT
SCREWDRIVERTO PUSH AND
ROTATE THE ClP ONTO THE
TWO BRASS STUDS ON THE
SlOE OF THE SWITCH CASE.
THE OPPOSITE SVE
FITTED IN THE SAME
MANNER BUT INVERTED
66
This page is intentionally blank
67
APPENDIX B
OFrlONAL DIGITAL W ATfMETER
R633B
ttrl-rING INSTRUcnONS
68
»--ESCRIPfION
Thewattmeteris fitted to die panelfasciain p~
INST
ALLA
of a blackDIN ~,
nON
;
Removethe 145 x 65 DIN caseby s1a:keningthe fascia pinch ~ws.
holdersand p$s die empty caseforward through the fucia.
Fit the wattmeterin the vacated~
Rotate to releasethe screw
widt dte screwtenninaJsat the lower side towardsthe tmit base.
A 3 core power supply lead for dIe optional wattmeter and separateoptional digital temperature
indicator is factory fitted to dIe following terminals00 dIe DIN rail connectionson die right handside
of dIe unit adj~ent to dIe power input lead. Their free endsare identifIed as follows:
49 (Earth - ColourG~ + Yellowstripe) FromDIN RailS
47 (Line - ColourRed) FromDIN Rail 8
48 (Neub'al-ColourBlack) FromDIN Rail 13
Thoseunits alreadyfitted with a digital temperature indicator (R6J3A) will ~
die JmCk of loose
links supplied to tap into the IX>wersupply. Refer to the wiring diagram on Page 71. H the tempezanue
indiCa1CK
gets in me way, unclip and push forward.
Units not fined with the digital temperature indicator will usethe threeunusedwires within the loom
identified as follows:
69
-
49 (Earth
ColourGreen+ Yellow stripe)
47 (Line
Colour Red)
48 (Neuttal- Colour BJack)
-
Before connecting to me watbneter,pass mese3 wires 1 turn through the ferrite ring supplied and
securenear to me watbneter.
The lOOmmred link from watuneterTenninall L to 3 AC V is usedin all cases.
The baseboardis pre-drilled with 4 off pilot holes 2mm dia. to receive the 2Ommlong self-tapping
screws(SFl/118). Theseshouldbe usedto securethe currenttransformer(E3/108) in position. Refer
to diagramon Page70.
Remove the compressorelectrical connectionscover. Detach the red line wire 31 and cut enough
adjacentcable ties to enablethis wire to passthrough the centreof the current transformerand back
to the compressor.Reconnectthe red line wire 31 to its original terminal on the compress<l'and refit
the cover.
Connect the 1200mm long red wires from the current transformer 51 and 52 terminals to the
conespondingterminalson the wattmeter. Twist thesetogetherto form a twisted pair of wires. Route
them throughthe releasablecableties securingthe loom to the fascia,and passthe pair 2 bJIDSthrough
the ferrite ring.
Tidy the loom using the cable ties IX"Ovided.
NOTE that if local regulations require, or any doubt exists concerning correct connection of the
instrument, the unit should be inspectedby a competentelectrician before supplying power to the
unit.
Refit d1erear paneL
Fit die tarel "Wattmeter"to me fascia in me spaceaboveme Wattmeter.
Restoreelectricalpower.
Switch on the main switch and verify the wattmeteris indicating. Minus valueswill appearif S1 and
S2 are reversed.i.e. S1 on the cWTenttransfonneris connectedto S2 on the wattmeter,and vice versa.
Or alternativelyif the direction of the compressorpower supplythrough the core of me transfonneris
reversed,the samenegativevalues will be seen.
70
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72
2
-1
4
Amendments
3
A
Sl,PPLY
TO WATTMETER
ANDOR
TEMPERATURE
INDICATOR
r
SIGNAL TO S1 AND S2
ON WATTMETER
'\
r~~#
...#...
~,
."
, ##
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TWICE THROUGH
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Sl.fIPL V FROM
FITTED LOOM
"--The supplier 18 req..-ed
~---
to detlVer goods strIctly acc«~
Remove all sharp edgeS and burrs.
-
-
I
\Dimensions:
mm \ by:
suppiiersresponsibility.
drawi1g. (afIP«1ent inspection is the
---
!Drawnby: JB IChecked
to
Fractions
Decimals
-
Limits unless otherwise stoteo
:Projec:tion
-
t 1/6'.
t 0.25 mm
!Issue:
1
TITLE:
--'-'
HTL:
~
KINGS SOMBORNE
P.
A.
HI..
TON
LTC
-
HAMPSHIRE
)-OOtri~
1.
-EN<:LANO
-
~-~