Diapositive 1

1
Building simulation conference - 27th July
2009 - Glasgow
Dynamic simulation of a complete solar assisted
air-conditioning system in an office building
using TRNSYS ID 555
Sébastien Thomas and Philippe André Department of
sciences and environmental management, University
of Liège 185 Avenue de Longwy, 6700 ARLON, Belgium
2
1
Presentation overview
1. Introduction 2. Simulation environment
overview 3. Building 4. HC emission and
distribution 5. HC production and storage 6.
Results Conclusion
2
4
5
3
6
3
1
Presentation overview
1. Introduction 2. Simulation environment
overview 3. Building 4. HC emission and
distribution 5. HC production and storage 6.
Results Conclusion
2
4
5
3
6
4
Introduction Solar air-conditioning context
Building cooling has an important impact on
energy consumption, therefore on CO2
emissions. Moreover, strong increase in cooling
installed capacity has been encountered last
years.

• Assets for solar energy
• It is one of the largest renewable energy
  ressource
• There are many ways to convert solar energy into
  cooling effect
• Sunny locations have more cooling needs

• Market available solar cooling technologies
• Absorption chiller
• Adsorption chiller
• Desiccant equipment
• PV panels with classical vapour compression
  chiller

5
Introduction key asset of solar energy
- The cooling load of buildings is generally high
when solar radiation is high ? yearly basis ?
daily basis
Src (2007). Solar Air-Conditioning, 2nd
International Conference Proceedings. Regensburg,
Germany, Ostbayerisches Technologie-Transfer-Insti
tut e.V. .
For an office building in August in Paris
6
Introduction Market status of Solar
air-conditioning

• Cooling power installed worldwide is 20 MW1.
• - It represents 250 to 300 installations, from
  few kW cold to 1 MW cold
• - Absorption is still leading the market
• Solar air-conditioning systems are installed in
• Office buidings (60)
• Laboratory, Hostels, Industry, Library,
• Development closely linked to its economical
  profitability, thus it is important to evaluate
  energy savings and their essential parameters

Solar cooling costs distribution 2
1. Src (2009). R. Gartner Sun wind energy
magazine 1/09
2. Src (2008) A. Preisler ROCOCO project
publishable part
7
1
Presentation overview
1. Introduction 2. Simulation environment
overview 3. Building 4. HC emission and
distribution 5. HC production and storage 6.
Results Conclusion
2
4
5
3
6
8
Simulation environment overview
Integral approach to evaluate energy savings
Complete simulation environment is presented
(TRNSYS is used to do this)

• Sub-systems implementation
• Building
• Hot and Cold distribution and emission
• Hot and Cold production and storage
• Climate
• Combined simulation of these sub-systems
• Possibility to substitute components

9
Simulation environment overview
TRNSYS implementation of Sub-systems
10
1
Presentation overview
1. Introduction 2. Simulation environment
overview 3. Building 4. HC emission and
distribution 5. HC production and storage 6.
Results Conclusion
2
4
5
3
6
11
Building modelling
IEA-ECBCS 48 European typical office building
1-c ? Paris Climate

• Complete building (3 identical floors)
• modeling including
• - 5 thermal zones
• - Ventilation
• - External shading modulation
• - Light intensity modulation
• Occupancy profile for each zone
• Internal gains profiles
• gt People
• gt Appliances
• gt Light

External shading modulation Manual solar
protections, shading fraction depends on solar
radiation on window surface. Solar protections do
not move when no occupancy
Stabat P. 2007. IEA48 Description of Type 1c
airconditioned office buildings for
simulation test,.IEA-ECBCS Annex 48
working document.
12
1
Presentation overview
1. Introduction 2. Simulation environment
overview 3. Building 4. HC emission and
distribution 5. HC production and storage 6.
Results Conclusion
2
4
5
3
6
13
Heating and Cooling emission and distribution
This layer is linked with HC production and
building layers
When computing heating and cooling load using
Type 56, control and distribution losses are not
handled implementation done here takes these
losses into account.
14
Fan Coil Units modelling

• It has been chosen to use a real FCU where
  manufacturer data is available.
• To model heating/cooling coil in a FCU, TRNSYS
  gives some possibilities
• - Using one of the numerous available types of
  heating cooling coil
• Effectiveness approach, Bypass approach,
• ? Tuned with one parameter, not accurate
  for the whole coil
• range of temperatures, mass flow
• Read manufacturer data using type 697
• ? Manufacturer data needs to be post
  processed to suit to type 697,
• it can be source of errors
• Implement a polynomial approximation of coil
  behavior based on the
• whole manufacturer data and integrate it into a
  TRNSYS equation
• ? This last solution is chosen
• Heating coil sensible heating energy f((Twater
  supply Troom),Water mass flow)

15
1
Presentation overview
1. Introduction 2. Simulation environment
overview 3. Building 4. HC emission and
distribution 5. HC production and storage 6.
Results Conclusion
2
4
5
3
6
16
Heating and cooling production and storage

• The picture represents the lowest energy
  consumption configuration for this layer
• Sub-system main components (for one floor)
• Evacuated tube collector 200 m²
• Storage tank 7 m³
• Absorption chiller 105 kWC
• COPnom 0.695
• Back up boiler 150 kW
• Cooling tower 263 kW
• Backup chiller 105 kWc
• COPnom 3.5

Mistake in the text 142,3 m² ? 200 m²
For each component, parameters have been
fixed based on market available equipment.
17
Simulation of solar air-conditioning system
chiller control
It appears that absorption chiller control has a
huge impact on energy consumption
caseA
3 strategies have been developed A Gas
and sun are the only energy sources B Storage
is not heated by boiler, when tank
temperature is not enough to feed ABS,
vapour compression chiller (VCC) is used.
storage is not used for building heating C
idem than B but storage is also used for
heating Comparison is done with classical A-C
(vapour compression chiller gas boiler)
caseB
caseC
For Paris climate
18
Absorption chiller new type
Existing type 107 energy balance but no
dynamic effect based on external performance
data file
Fraction of nominal capacity Fraction of design
energy input
Read in Data file
Depends on current conditions Chilled water set
point, Entering cooling water temperature, Inlet
hot water temperature, part load ratio (fraction
of design load)
Cold production and Hot water consumption are
computed

• Things to take care
• Fraction of nominal capacity is limited to 1 ?
  Rated power is maximum power
• - Part load ratio independent of current
  condition (based on rated capacity only)

19
Absorption chiller new type
- Part load ratio independent of current
condition (based on rated capacity only)
When dealing with classical chiller (e.g. type
655), part load ratio (so called fraction of
design load in type 107) is the load met by the
chiller divided by the capacity of the chiller at
the given conditions. Obviously it is between 0
and 1 In type 107, part load ratio is load met
by the chiller divided by the capacity of the
chiller at the rated conditions. It implies
values larger than 1 and has less sense than
previous definition
New type 255 existing type 107 part load
ratio depending on current conditions
20
1
Presentation overview
1. Introduction 2. Simulation environment
overview 3. Building 4. HC emission and
distribution 5. HC production and storage 6.
Results Conclusion
2
4
5
3
6
21
Simulation of complete solar air-conditioning
system results
Building Heating and Cooling loads
For Paris climate
22
For Paris climate
Simulation of complete solar air-conditioning
system results
23
Simulation of complete solar air-conditioning
system results
HC and auxiliaries consumptions have been
computed
For Paris climate
HC
Auxiliaries
Case A
For Paris climate
24
Conclusions and next developments
A complete office building solar air-conditioning
application was presented and divided into three
major parts to enhance readability. System
control has a huge impact on energy consumption.
It appears that VCC chiller as backup is useful
for energy savings (but implies cost of new
equipment). Savings reach more than 30 ! Solar
air-conditioning is efficient when used in
efficient buildings. Work can be done to decrease
cooling load. In actual office building
simulations, auxiliaries have a great impact on
the whole building energy consumption.
Limitations Next developments - Steady state
absorption chiller model - Control strategy
improvements should be done (e.g. adjust hot
water temperature to cooling load) -
Convergence problems with hot water storage