Transcript Development of EUC (End User Computing) System for the

Development of
EUC (End User Computing) System
for the Design of HVAC
(Heating, Ventilation and Air Conditioning)
O.Yoshida, M.Andou
Tokyo Gas Co., Ltd.
Contents
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Introduction
Feature of the EUC system
Wide variety of DB (data-base)
Original user-subroutines
Verification of DB
Conclusions
Introduction
• CFD methods have become a promising tool to
optimise design parameters of HVAC by predicting
thermal environment in buildings.
• While many advantage are expected, CFD codes still
require lots of expertise and time for designers to
model and predict indoor environment.
• Wider application of CFD has been expected, in
particular, to the field of EUC that designers and even
sales engineers can easily take advantage of.
An EUC system for the optimal design
of HVAC has been developed.
Feature of the EUC System
Utilisation of PHOENICS
• Flexible pre-processor
• Powerful solver
• Easy VR post-processor
Uniquely customised to predict indoor environment
in faster, more accurate and user-friendly manners
• Wide variety of DB (data-base)
for the analysis of HVAC
• Original user-subroutines
• Verification of DB
Wide Variety of DB (Data-base)
The system incorporated DB compiled during
various cases of predictions and experiments.
A/C DB
Q1
Q1
A/C type
Building DB
• The DB provides typical specifications of a variety
of air-conditioners and buildings as a set of Q1 files.
• It also maintains previous Q1 and PHI
files as reference, which can be readily
upgraded to predict similar problems .
Original User-subroutines
• Along with the DB, series of practical usersubroutines have been developed using GROUND.
• These user-subroutines are applicable to predict ideal
performance and operating conditions of airconditioning units under desired optimal thermal
environment.
• Optimisation of input conditions such as efflux
temperature is conducted to obtain desired thermal
environment in a room.
Original User-subroutines - Example
Prediction of Optimal Efflux Temp.
• Mean temperature at the height of 0.6m for each of
perimeter and interior areas needs to be 22℃ to
achieve desired thermal environment.
Unit_P(Q=9m3/min) Unit_I1(Q=6)
Unit_I2(Q=6)
Window
Perimeter (Area_P)
Interior (Area_I)
Z=0.6m
Office Room Type (Outside of Temp. = 0 C)
• Efflux temperatures are separately controlled with
reference to respective area temperature.
Original User-subroutines - Example
Algorithm
Start
Tm_start=22 C, Tm_end=22 C, Te_start=40 C
60
EARTH Solution
Efflux Temp.of Unit_P
Mean Temp.of Area_P
Efflux Temp.of Unit_I
Mean Temp.of Area_I
Calculate Tm
Calculate Rlx (Relax. factor)
by Residual of NETSOURCE
Te=Te+(Tm_end-Tm)*Rlx
Temperature(C)
50
30
20
10
No
LSWEEP ?
Yes
End
Te
40
Tm
0
200
400
600
800 1000 1200 1400 1600 1800
Sweep Number
Temperatures. vs. Sweep No.
Original User-subroutines - Example
Temperature Distributions
Efflux temp ≒ 30.6C
Efflux temp ≒ 29.8C
Center plane of A/C units
Mean temp ≒ 22.0C
Mean temp ≒ 22.0C
Plane at Z=0.6m
Verification of DB
• Prediction accuracy of DB of the system was verified
a-priori, by comparing with detailed measurements.
Computation
Measurement
Verification
• Know-hows to generate a numerical grids have
been compiled to secure practical accuracy with
minimum calculation time .
Verification of DB - Example
Artificial Climatic Room
Air-Conditioning unit
3D traverse apparatus
Schematic Diagram
Model Room
Verification of DB - Example
Heating Conditions
Air-Conditioning unit
Neighboring Temp. = 10 C
Sink
Efflux Temp. = 46C
Outside of Temp. = 0 C
Living Room Type
Verification of DB - Example
Numerical Analysis
• PHOENICS 3.2
• Steady states
• Rectangular grids
38×32×33 = 40128cells
• Elliptic-staggered equation
• k-epsilon turbulence model
• Hybrid differencing schemes
• Boussinesq buoyancy model
Numerical Grid
Verification of DB - Example
Center Plane of Air Conditioner
Measured
Computed
Verification of DB - Example
Center Plane of Model Room
Measured
Computed
Verification of DB - Example
Temperature Profiles
2.0
Height(m)
●
Com puted
Me as ured
1.5
1.0
Ce nte r of Room
X=2.17m
Y=1.735m
0.5
0.0
0
10
20
30
Temperature(C)
40
50
Conclusions
• An useful EUC system for the optimal design of
HVAC has been developed using PHOENICS.
• The system incorporated DB for the analysis of
HVAC as a set of Q1 files .
• Along with the DB, practical user-subroutines have
been developed.
• Prediction accuracy of the system was verified apriori, by comparing with detailed measurements.
• Computed result with incorporate DB was in good
agreement with measured result.