Measurement of the Ventilation Parameters to the Hot Water Heating Systems Using the Solar Energy
MEASUREMENT OF THE VENTILATION PARAMETERS TO
THE HOT WATER HEATING SYSTEMS USING THE SOLAR
ENERGY
Dumitru Vlad, Diana-Mura Badea, Valentina Bajenaru, Adrian Iordache
National Institute of Research and Development in Mechatronics
and Measurement Technique, Sos. Pantelimon 6-8, Bucharest 021631, Romania
Email: didi@cefin.ro, dianamura@yahooo.com, valibajenaru@yahooo.com, energyadydj2003@yahoo.com
Abstract: Any supplying equipment with hot consumption water may be described by the help of 4
component systems (delivery acm, distribution acm, accumulation acm, preparation acm) thus defining
how the energies are used. The methodology and calculation stages follow the inverse transmission
direction of the energy in the supplying equipment with hot water, respectively the calculation direction is
inverse to the energy flow direction.
The most important elements of the policy in the field of producing energy for heating are:
 Increasing changing efficiency of the primary energetic resources, specially the fossil ones;
 Increase the intake of the renewable resources in using the energy for heating.
The unconventional sources used in heat supply and heat consumption water may be classified according
to their origin:
 Renewable energy sources using heating pumps, solar energy, geothermal energy
 Thermal energy from biomass
Keywords: Ventilation parameters, hot water, solar energy.
1. Solar energy
The heat obtained from the photo thermal conversion of
the solar energy in the solar collectors may be
transported in the heated space directly, without any
overheating. The solar equipments for heating the
buildings in our conditions should be designed with the
additional heating source.
The solar equipment may cover the yearly consume
only 25-30% at the beginning and at the end of the
heating season. During the periods with external low
temperatures a supplementary source covers the
designed necessary heating. At the equipment may be
coupled an alternative heating equipment.
Using the solar energy in heating equipments at low
temperatures is optimal for an intensive use of the solar
energy. Because of the solar energy variation during the
day and the year the solar equipments are designed with
heat accumulation. The most common field using the
solar energy in equipments means to produce
consumption heat water, because the equipments for
preparing the heat consumption water are simple and
with high efficiency compared to similar equipments
used for solar energy conversion.
The main elements of a solar equipment for preparing
heat water are generally solar collectors, heat converters
with accumulation – boilers, heat converters without
accumulation, accumulation reservoirs and additional
auxiliary source.
Except the solar sensor the common element of all the
schemes, the exception is the simplest variant (the
system variant with themosiphon) is the automation
equipment which provides the good functioning of the
equipment both during sunny periods and cloudy
periods. The automation equipment may be additional to
a thermosiphon system if its presence is asked by the
system complexity, by the equipment flow and by the
operating mode.
Mainly are used 2 types of equipments which are
classified according to thermal agents circulation:
 with simple circulation (thermosiphon) – when the
circulation of the thermal agent through the collector
is realised naturally based on the density difference
between the hot and cold water. This type is used for
small heat water flows;
 with forced circulation – when the circuit has one or
more pumps. This type is used when heat water flows
are important and can not be achieved a natural
circulation.
2. Bivalent solar equipment
The bivalent solar equipment for heating and preparing
the hot consumption water is a combined equipment
using solar energy and a thermal central, according to
the following scheme.
The equipment functions as follows: the solar energy is
sent to the water in the collector which as heats is sent
to the boiler coil where provides heat, becomes cold and
then it comes back to the collector for heating again and
The Romanian Review Precision Mechanics, Optics & Mechatronics, 2012, No. 42
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Measurement of the Ventilation Parameters to the Hot Water Heating Systems Using the Solar Energy
the cycle is repeated.
Figure 1: Bivalent solar equipment with thermal
central/heating – solar collectors – tank for water
heating – boiler for hot water – expansion vessel
The circulation between the collector and the switch is
provided by the thermal pressure:
H = hg(ρr – ρc)
where
ρr si ρc are the cold and hot water densities;
h the vertical distance between the collector and the
boiler coil.
In a cycle of 24 hours the equipment acts as follows:
 During the first half of the day the water from the
primary circuit becomes hot and is collected in the
hit switch and the hot water distribution from the
secondary circuit to the consumer is made by
introducing cold water to the inferior part of the coil
and the hot water comes out to the superior/top part.
 During the second half of the day the water from the
primary circuit has the same circuit (collectorswitch-back) the hot water distribution to the
consumer is made by introducing cold water to the
inferior part of the coil and so hot water comes out
to the median part of the coil. The water from the
superior half of the switch remains hot ant it is
maintained hot till the next day.
 During the first hours of the morning (till it arrives
to the normal performance) it may be consumed the
hot water collected in the upper aria, by connecting
the coil to the switch at both extreme ends (superior
and inferior part).
3. Calculation of the necessary hot wastewater
The necessary data which we suppose are known and
which are going to be necessary for calculations will be
introduced when they are necessary (number of persons
in the house, batteries supplying hot water, etc.).
Calculation method
We suppose we have to supply the following
consumers:
 bathroom sink
50
 flexible shower
 kitchen sink
 home central heating in winter.
For each of these users I chose a daily functioning time.
Thus, we considered that the shower will be used by a
person 8 minutes/day, the sink 20 minutes/day, and the
other sink 10 minutes/day. For each battery we chose
the average hot water consumption. Thus, we
considered the shower will use 6 litters/min., the sink 5
litters/min., the other sink 3 litters/min. We considered
in the house are living 3 persons.
These data have been included in the table. Because the
water consume is not continuous and the time used for
hot water consumption (during a day) means approx. 1
hour in all in litters/hour equal with the total litters
consumption/day.
Table 1
Shower Sink Sink Total
Total
Time to use for a person
8
20
10
38
(min/day)
Consumption/ pers.
6
5
3
14
(l/min.)
Daily consumption of a
person
(l/day)
Daily consumption for 3
persons
(l/day)
48
100
30
178
144
300
90
634
The water necessary flow:
=
0,00027 m3/s
Calculation of the heat necessary:
In order to size the equipment and to choose the solar
panels we must know the hit quantity the water has to
absorb for heating.
For this we consider the temperature of the cold water
of tr=15°C
The waste hot water we wish to obtain will have the
next temperature tc=45°C
The solar panel must bring the water temperature with
Δt=45-15=30°C For this will be necessary a hit quantity
equal to
Q = mcΔt = ρa x V x c Δt
where:
m – mass flow for cold water that must be heated during
a day;
c – specific heat of the water to an average temperature
is 30°C equivalent to 4,179 Kj/kg*grad;
ρa - water density to an average temperature of30°C is
995,7 Kg/m3
This heat is the necessary heat to heat all the water used
in one day. Because the consumption of hot water is not
continuous we may appreciate Q as being measured in
kW/h.
The Romanian Review Precision Mechanics, Optics & Mechatronics, 2012, No. 42
Measurement of the Ventilation Parameters to the Hot Water Heating Systems Using the Solar Energy
Solar panels sizing and choice
We suppose that a solar panel of 1 mp produces a hit
flow of 2kW/day. Thus, for the thermal necessary of
33.5 kW we shall need a the panels surface of 33/2 =
16.5 mp. Choosing the ACV type KAPLAN s2.7 solar
panel from the ACV company with a gross aria of 2.91
mp and a net aria of 2.7 mp will result a number of
16.5/2.7=6 panels for this equipment.
 Easy use because of simple manipulation;
 Housing easy to fix with a special appearance.
Boiler choice and size
To choose the boiler will be taken into consideration the
thermal necessary and the coil power and its volume
will be determined by the formula:
Q = 0,065 V
where :
V – the boiler volume
Q – the heat necessary
It results: V = 33,5/0,065
Expansion vessel sizing and choice
The calculation formula for the vessel sizing is
according to:
Where:
E – enlarging coefficient (e is approx. 0.035)
C – water system capacity (between 10 and 20 lt. For
each kw power) here it is equal with…in orig…
Pi -load pressure (approx. 1.5 bar)
Pf - max. functioning pressure (approx. 4 bar)
The result is:
Tubes and pipes choice (connection elements)
For the tubes it is chose a SILMET ESENCO ø 18 X 1
mm copper pipe . To reduce the heat loses the copper
pipe will be covered with SIMLET ESENCO isolation.
The connection elements will be made of copper (tees,
jacks, fittings). The thermo technical parameters
measured (monitor) to a preparing system for the hot
water composed by solar panels are:
 exit water temperature from the solar system;
 cold water temperature;
 hot water temperature;
 the energy quantity consumed.
A device which provides the equipment automation for
preparing the waste water is CR2S2 having the
following characteristics:
 Display monitoring system;
 Till 4 sensors for temperature Pt 1000;
 2 relays semiconductors for variable speed
adjustment;
 May be chose 9 basic systems;
 Measurement of the heat quantity;
 VBus®
 Function control;
 Thermostat function (programmed);
 Changing in parameters and system control are
possible by centre services software;
Figure 2: device (with display- detail)
Characteristics
Housing: Plastic, PC-ABS şi PMMA
Protection model : IP 20 / DIN 40050
Environment temperature: 0 … 40°C
Dimensions172 x 110 x 46 mm
Fixing: fixing in the wall, possible integration in the
control panel
Display: monitor system to visualise the equipment,
display 16 segments, 8 symbols for the system status
and function control lamp.
Use: by 3 keys from the front part of the housing.
Functions: Regulator for temperature difference with
the equipment functions that may be supplementary
accessed.
The functioning control according to BAW directive,
counter functioning time for the solar pump, collector
tube function, variable speed adjustment, thermostat
function and heat quantity accounting.
Inputs: 4 for temperature sensors Pt1000
Outputs: 2 semiconductors relays
Transmission: VBus®
Source of energy: 220… 240V~
Complete interruption capacity: 4 (2) A 220 …
240V~
The control unit has VBus® for data communication
with energy supply to the external modules.
The connection is made mo matter the polarity is, by the
2 terminals marked with “Vbus”. To these data channels
may be connected more VBus®, ex.:
 WMZ-M1calorimeter module
 Big displays GA3
 Data memory DL1
 Tele indication DFA2
In addition the control unit may be connected to a PC by
a RS - COM laptop. By the help of VBus®, may be
modified the adjusting parameters and the measurement
values may be read, processed and visualized. Because
of the software are possible a comfortable control
function and the system adjustment.
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Measurement of the Ventilation Parameters to the Hot Water Heating Systems Using the Solar Energy
The device screen
Conclusions
The screen of the device (active scheme of the device)
shows the selected scheme by the control unit.
It is composed by more symbols of the system
competences, are intermittent, appear permanently on
the screen or are hidden.
Taking into consideration the importance of the
energetically efficient equipment and the afferent
economic impact for the energy invoices and
investments costs, the industry for electrical equipments
shows more and more interest and a greater variety of
energetic efficient devices are offered by the world wide
suppliers. The internet specialised sites are a great help
for choosing electronic devices energetically efficient.
The measurement aims to provide proves on the energy
consumption, comfort and the inhabitancies from the
passive house. There are measurement points to
determine consumptions and also special measurements.
In the passive house is a central continuous collecting
data system. All the measurement sensors are connected
by Mbus or Field Bus network and transmit signals on
the monitored parameters each second. The analysis of
the monitored data may be done by a connection to a
modem.
Figure 3: Device components
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The Romanian Review Precision Mechanics, Optics & Mechatronics, 2012, No. 42