| Common design methods can not be used to analyze and assess airflow accurately in large space buildings such as gymnasiums. In recent years, with the development of computer industry and Computational airflow thermal Dynamics, it becomes possible to simulate and predict air comfort of design system based on CFD technology in buildings .Here the professional software Airpak2.1 introduced by Fluent, Inc. is used. Zero equation turbulence model is applied for numerical simulation of airflow in the hall of a certain gymnasium under various audience rate. The results of airflow and temperature field are obtained and verified through field test for its accuracy, so that it can provide certain guidance for the design and commission of practical air conditioning projects. Results show that for side-supply and downward-return style using nozzle as a diffuser, under different audience rate, the necessary refrigerating capacity of air conditioner can be lowered through adjusting the distribution ratio of flow in different air ducts, the injection angle of nozzles and the temperature of supply air. In summer, the supply air flow rate can be reduced by about 30%. while in winter, the temperature of supply air can be lowered by 3℃, so energy saving strategy can be achieved.By means of Heat Economic Analysis, 3 common schemes of cool and heat source, i.e. air-cooled screw chiller (heat) pump, water-cooled screw water chillers and steam-to-water heat exchanger, and ground-source heat pump (GSHP), are compared. Results show that under different audience rate and different commission time, the operating cost per refrigerating capacity of GSHP is the lowest, and the rate of return for additional initial investment increases with decreasing audience rate and commission time. As a result, GSHP is more suitable for applications with larger refrigerating capacity and longer commission time during all through the year, which can reflect the advantage of energy saving for GSHP obviously.
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