• Matlab
• Free versions / open source codes:
–Scilab http://www.scilab.org/
• MathCad:
• Mathematica: http://www.wolfram.com/mathematica/
• LabView: http://www.ni.com/labview/
• EES: http://www.fchart.com/ees/
• Modelica: https://www.modelica.org/
• ….

• Discuss the final project assignment
• Finnish with Review of HVAC systems
– Air-conditioning in Air Handling Units (AHU)
– Refrigeration cycles
• Building-System-Plant connection

• Today and on Monday Extended office hours for project topic and objective discussion
• After that you will prepare more detailed project proposal (1 – 2 pages) with
- Project objective
- Methodology
- Expected results
Any schematic drawing is welcome

1) Optimization of building envelops glass area ,shading,….
2) Effect of internal loads on energy consumption
..................
Systems
1) Impact of HVAC systems
2) Design of solar system (PV or hot water)
……………..
Life cycle cost analysis in each project
Detailed analysis!

Chiller
Cooling tower
Water 52 ° F Water 120 ° F
Outside air 95 ° F
Water 100 ° F
Building
Water 42 ° F Inside 75 ° F
Task: analyze COP for the whole year and different locations

Example of HVAC thermal storage systems
(in combination with a cooling machine / heat pump)
Summer Winter
In the summer, the earth acts as a cooling tower. The Cooling Machine loads the loop with heat, sending warmed water to be cooled by the earth
In the winter, the earth acts as the boiler. The Heat
Pump extracts heat from the loop, sending cooled water to be warmed by the earth.

• It is very expensive to optimize each residential building
• We optimize example buildings to develop local codes
UT Solar Decathlon 2007 Test house (PRC) Home Research Lab

• Heat recovery systems,
• Attic problem,
• Mass transfer (moisture,…)
• Vented cavity walls - exam problem
• Green roof model
Your ideas…

• 11/12/12 - project defined and approved
• 11/20/12 - generated model
• 11/29/12 - report the preliminary results
• 12/04/12 - oral presentations
• 12/06/16 - project paper submission

• GRADING CRITERIA (30% of your final grade):
• 1) Analysis approach:
• - Modeling quality
• - Result accuracy
• - Result analysis
• 2) Deliverables:
20%
20%
20%
60%
40%
• - Quality of the final report
• - Quality of oral presentations
• - Submission timeline
25%
10%
5%
• Undergraduate students
– Engineering report
• Graduate students
– Research report

HVAC System
(AHU and distribution systems)
Plant
(boiler and/or
Chiller)
Building

Building HVAC Systems
(Primary and Secondary Building Systems)
AHU – Air Handling Unit
Fresh air
For ventilation
AHU
Distribution systems
Primary systems
Air transport
Electricity
Cooling
(chiller)
Heating
(boilers)
(or Gas) Gas
Secondary systems
Building envelope
HVAC systems affect the energy efficiency of the building as much as the building envelope

AHU
Air-conditioning in
Air Handling Unit (AHU)
Roof top AHU fresh air mixing filter
Exhaust
AHU schematic
From room flow control dampers
Return fan
Supply fan cool water hot water
To room
Fan air from building
Evaporator
Gas/Electric
Heater to building
Compressor and Condenser

Case for
Summer in Austin
SA
IA
MA
OA

Released energy
(condenser)
T outdoor air
T cooled water
- What is COP?
- How the outdoor air temperature affects chiller performance?
Cooling energy (evaporator)

Load System Plant model
Building
Q buiolding
Q
Heating/Cooling
System including
Ventilation and
Dehumidification
Plant
Integrated models
Building
Heating/Cooling
System
Plant

Schematic of simple air handling unit (AHU)
Q
C
T f,in
T f,ou t
Q
H
Mixing box
(1-r)m
S
T
O w
O m
S
T
M w
M rm
S
T
R w
R m
S fans cooler heater
T
S w
S room T
R w
R
Q room_sensibel
Q room_latent m - mass flow rate [kg/s], T – temperature [C], w [kg moist
/kg dry air
], r - recirculation rate [-], Q energy/time [W]

Energy and mass balance equations for
Air handling unit model – steady state case
The energy balance for the room is given as:
Q room _ sensible
 m
S c p

T
R

T
S
 m
S c p is the supply air mass flow rate
- specific capacity for air,
T
R
T
S is the room temperature, is the supply air temperature.
The air-humidity balance for room is given as:
Q room _ latent
 m
S
 w
R
 w
S

 i phase _ change w
R and w
S are room and supply humidity ratio i phase _ change
- energy for phase change of water into vapor
The energy balance for the mixing box is:
T
M

( 1
 r )

T
O
 r

T
R
‘r’ is the re-circulated air portion,
T
O
T
M is the outdoor air temperature, is the temperature of the air after the mixing box.
The air-humidity balance for the mixing box is: w
M

( 1
 r )
 w
O
 r
 w
R w
O w
M is the outdoor air humidity ratio and is the humidity ratio after the mixing box
The energy balance for the heating coil is given as:
Q
Heating
 m
S c p
( T
S

T
M
)
The energy balance for the cooling coil is given as:
Q
Cooling
 m
S c p
( T
S

T
M
)
 m
S
 w
S
 w
M

 i phase _ change

T w_out
Radiant Panel c on v e cti on
T surface
T zone_air
Ro om (zone 1) radiant panel layer (water t ube)
T w_in
Q rad_pan rad iatio n
T surounding m ,T s
= const.
air supply syst em
Q zone

The total cooling/heating load in the room
Q zone

Q rad _ pan

Q air
Q air

( mc p
) sup ply _ air
( T sup ply _ air

T room _ air
) The energy extracted/added by air system
Q rad _ pan
The energy extracted/added by the radiant panel:
The energy extracted/added by the radiant panel is the sum of the radiative and convective parts:
Q rad _ pan

Q radiation

Q conv
  h radiation , i
A panel
( T panel

T surface , i
)
 h conv
A panel
( T panel

T air
)
T he radiant panel energy is:
Q rad _ pan
 mc pw
( T w _ out

T w _ in
)