Equation solvers

1
Equation solvers

• 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/
• .

2
Lecture Objectives

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

3
Final project

• 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

4
Topics related to the Commercial Buildings

• 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!

5
Example of HVAC water cooled chiller
Chiller
Cooling tower
Building
Water 52F
Water 120F
Outside air 95F
Inside 75F
Water 100F
Water 42F
Task analyze COP for the whole year and
different locations
6
Example of HVACthermal storage systems(in
combination with a cooling machine / heat pump)
Winter
Summer
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.
7
Residential buildings

• It is very expensive to optimize each residential
  building
• We optimize example buildings to develop local
  codes

8
Modeling for optimization of Home Research Lab
(PSP)
9
Detail Modeling (your model)

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

10
Project Timeline

• 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

11
Project Grading

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

12
Building-System-Plant
HVAC System (AHU and distribution
systems)
Plant (boiler and/or Chiller)
Building
13
Building HVAC Systems (Primary and Secondary
Building Systems)
AHU Air Handling Unit
Distribution systems
Fresh air For ventilation
AHU
Primary systems
Air transport
Electricity
Secondary systems
Cooling (chiller)
Heating (boilers)
Building envelope
HVAC systems affect the energy efficiency of the
building as much as the building envelope
Gas
(or Gas)
14
Air-conditioning in Air Handling Unit (AHU)
AHU
AHU schematic
Exhaust
From room
Return fan
flow control dampers
Supply fan
Compressorand Condenser
Fresh air
To room
Outdoor air
hotwater
coolwater
15
Processes in AHU presented in Psychrometric in
psychrometric
Case for Summer in Austin
OA
MA
IA
SA
16
Refrigeration Cycle
Released energy (condenser)
T outdoor air
T cooled water
- What is COP? - How the outdoor air temperature
affects chiller performance?
Cooling energy (evaporator)
17
Integration of HVAC and building physics models
Load System Plant model
Building
Heating/Cooling System
Plant
Qbuiolding
Q including Ventilation
and Dehumidification
Integrated models
18
Example of System ModelsSchematic of simple air
handling unit (AHU)
Mixing box
m - mass flow rate kg/s, T temperature C, w
kgmoist/kgdry air, r - recirculation rate -,
Q energy/time W
19
Energy and mass balance equations for Air
handling unit model steady state case
The energy balance for the room is given as
mS is the supply air mass flow rate cp -
specific capacity for air, TR is the room
temperature, TS is the supply air temperature.
The air-humidity balance for room is given as
wR and wS are room and supply humidity ratio
- energy for phase change of water into vapor
The energy balance for the mixing box is
r is the re-circulated air portion, TO is the
outdoor air temperature, TM is the temperature
of the air after the mixing box.
The air-humidity balance for the mixing box is
wO is the outdoor air humidity ratio and wM is
the humidity ratio after the mixing box
The energy balance for the heating coil is given
as
The energy balance for the cooling coil is given
as
20
Non-air system Radiant panel heat transfer model
21
Non-air system Radiant panel heat transfer model
The total cooling/heating load in the room
The energy extracted/added by air system
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
The radiant panel energy is
22
(No Transcript)