The effect of the air supply temperature on the performance of a displacement ventilation (DV) system has been investigated. The study looks into the case of a typical office building in Hong Kong, under local thermal environment and airflow conditions. These are characterised by the high cooling load density, which commonly occurs in Hong Kong. The lower supply temperatures were found to result in higher draft effects, yet increasing temperatures leads to an increase in the predicted percentage of dissatisfied people (PPD). The DV system was found to provide acceptable thermal comfort at certain air supply temperatures. The levels of PPD could be marginal should the parameters of the system not be optimised.
Lin JZ , Chow TT , You F , Zhou J-j , Zou Y-h : A partial differential model for the pyrolysis of materials with movable residual layer . Mechan Adv Mat Structures. 2005;12(1): 1-7 .
2.
Yuan X , Chen Q , Glicksman LR : A critical review of displacement ventilation . ASHRAE Transactions1998;104(1A): 78-90 .
3.
Yuan X , Chen Q , Glicksman LR : Models for prediction of temperature difference and ventilation effectiveness with displacement ventilation . ASHRAE Transactions1999;105(1): 353-367 .
4.
Yuan X , Chen Q , Glicksman LR , Hu Y , Yang X : Measurements and computations of room airflow with displacement ventilation . ASHRAE Transactions1999;105(1): 340-352 .
5.
Hu S , Chen Q , Glicksman LR : Comparison of energy consumption between displacement and mixing ventilation systems for different U.S. buildings and climates . ASHRAE Transactions1999;105(2): 453-464 .
6.
Yuan X , Chen Q , Glicksman LR : Performance evaluation and design guidelines for displacement ventilation . ASHRAE Transactions1999;105(1): 298-309 .
Bauman FS , Arens EA , Tanabe S , Zhang H , Baharlo A : Testing and optimizing the performance of a floor-based task conditioning system . Energy Buildings1995;22: 173-186 .
9.
Matsunawa K , Iizuka H , Tanabe S : Development and application of an underfloor air-conditioning system with improved outlets for a “smart” building in Tokyo . ASHRAE Transactions1995;101(2): 887-901 .
10.
Hedges A , Michael AT , Parmelee SL : Reactions of office workers and facilities managers to underfloor task ventilation in offices . J Architect Planning Res1993;10(3): 203-218 .
11.
McCarry B : Underfloor air distribution systems: benefits and when to use the system in building design . ASHRAE Transactions1995;101(2): 902-911 .
12.
Gan G : Numerical Investigation of local discomfort in offices with displacement ventilation . Fuel Energy1996;37(2): 82-157 .
13.
Trent W : Humidity, temperature in air supply ducts . Engineered Systems1997;14(10): 50-54 .
14.
Chen Q , Suter P , Moser A : Influence of air supply parameters on indoor diffusion . Building Environ1991;26(4): 417-431 .
15.
Lian Z : Experimental study factors that affect thermal comfort in an upward-displacement air conditioned room . HVAC Res2002; 8(2): 191-200 .
16.
ASHRAE : Ventilation for acceptable indoor air quality, ANSI/ASHRAE Standard 62-1999. ASHRAE, Atlanta, USA , 1999.
17.
Fanger PO , Melikov AK , Hanzawa H , Ring J : Turbulence and draft . ASHRAE Journal.1989;31(7): 18-23 .
18.
Int-Hout D : Thermal Comfort Calculations - A Computer Model . ASHRAE Transactions1990;96(1): 840-844 .
19.
ASHRAE : ANSI/ASHRAE Standard 55-1992, Thermal environmental conditions for human occupancy. Atlanta: American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. Meddelande M85: 24. 1992.
20.
Fanger PO , Christensen NK : Chart for prediction of draft . Australian Refrigeration, Air Con Heating1986;40(7): 46 .
21.
Huber AH : Performance of a Gaussian model for centerline concentrations in the wake of buildings . Atmos Environ1988;22(6): 1039-1050 .
22.
Lin Z , Chow TT , Qiuwang Wang , Fong KF , Chan LS : Validation of CFD model for research into displacement ventilation . Architect Sci Rev2005 (accepted for publication).
23.
AEA Technology , CFX-4.2 Environment User Manual, vols 1 to 4, 1997.
24.
Launder BE , Spalding DB : The numerical computation of turbulent flows . Computer Methods Appl Mech Energy1974;3: 268-289 .
25.
Chen Q : Comparison of different k-models for indoor airflow computations . Numerical Heat Transfer1995;28(B): 353-369 .
26.
Chen Q : Prediction of room air motion by Reynolds-stress models . Building Environ1996;31(3): 233-244 .
27.
Yakhot V , Orzag SA , Thangam S , Gatski TB , Speziale CG : Development of turbulence models for shearflows by a double expansion technique . Phys Fluids A1992;4(7): 1510-1520 .
28.
Chen Q , van der Kooi J , Meyers A : Measurements and computations of ventilation efficiency and temperature efficiency in a ventilated room . Energy Buildings1988; 12(2): 85-99 .
29.
Xu W , Chen Q , Nieuwstadt FTM : A new one-equation turbulence model for near-wall natural convection . Intl J Heat Mass Transfer1998;41: 3161-3176 .
