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.

• Introduction

• Feature of the EUC system

• Wide variety of DB (data-base)

• Original user-subroutines

• Verification of DB

• Conclusions

Contents

Introduction• CFD methods have become a promising tool to optim

ise 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 SystemUtilisation 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.

• 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 .

A/C DB A/C type

Building DBQ1 Q1

Original User-subroutines• Along with the DB, series of practical user-subroutine

s have been developed using GROUND.• These user-subroutines are applicable to predict ideal

performance and operating conditions of air-conditioning 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 - ExamplePrediction 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.

Office Room Type (Outside of Temp. = 0 C)

Window

Z=0.6m

• Efflux temperatures are separately controlled with reference to respective area temperature.

Unit_P(Q=9m3/min) Unit_I1(Q=6) Unit_I2(Q=6)

Perimeter (Area_P) Interior (Area_I)

Original User-subroutines - Example

AlgorithmStart

Calculate Tm

Calculate Rlx (Relax. factor) by Residual of NETSOURCE

Te=Te+(Tm_end-Tm)*Rlx

LSWEEP ?

EndYes

EARTH Solution

No

Tm_start=22 C, Tm_end=22 C, Te_start=40 C

Temperatures. vs. Sweep No.

Tm

Te

10

20

30

40

50

60

0 200 400 600 800 1000 1200 1400 1600 1800

Efflux Temp.of Unit_P

Mean Temp.of Area_P

Efflux Temp.of Unit_I

Mean Temp.of Area_I

Tem

pe

ratu

re(C

)

Sweep Number

Original User-subroutines - Example

Temperature Distributions

Plane at Z=0.6m

Mean temp 22.0C Mean temp 22.0C≒ ≒

Center plane of A/C units

Efflux temp 30.6C Efflux temp 29.8C≒ ≒

Verification of DB

Computation Measurement

Verification

• Prediction accuracy of DB of the system was verified a-priori, by comparing with detailed measurements.

• 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

Schematic Diagram

3D traverse apparatus

Air-Conditioning unit

Model Room

Verification of DB - Example

Heating Conditions

Living Room Type

Efflux Temp. = 46C

Sink

Air-Conditioning unit

Outside of Temp. = 0 C

Neighboring Temp. = 10 C

• PHOENICS 3.2• Steady states• Rectangular grids 38×32×33 = 40128cells• Elliptic-staggered equation• k-epsilon turbulence model • Hybrid differencing schemes• Boussinesq buoyancy model

Verification of DB - Example Numerical Analysis

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

0 10 20 30 40 500.0

0.5

1.0

1.5

2.0ComputedMeasured

Temperature(C)

Hei

gh

t(m

)

Center of Room X=2.17m Y=1.735m

●

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 a-

priori, by comparing with detailed measurements.• Computed result with incorporate DB was in good

agreement with measured result.