Research on the Inter-zonal Heat Transfer Coefficient in Thermally Stratified Environment of Floor-Level Air-Supply System

Abstract

Stratum ventilation with air supply terminal located on the floor level near side-wall is typical for large space building, consequentially resulting in vertical thermal stratification. Heat accumulation in the upper part of unoccupied zone will have significant effect on the cooling load of occupied zone. In order to accurately predict the indoor thermal environment and load characteristics of large space building, and to calculate the heat migration occurring in the thermally stratified environment, the determination of inter-zonal heat transfer coefficient C_b is critical. This paper discusses the method to calculate inter-zonal heat transfer coefficient to represent a large space building. In a scaled laboratory, five experiment cases with different exhaust air flow ratios, heat source powers are studied. CFD simulations of the same cases are performed. The vertical temperature distribution and detailed cooling load results of the entire system and occupied zone are verified based on the experiment results. By dividing the whole space vertically into two and five zones, inter-zonal heat transfer coefficient C_b under different heat source heights is calculated from the CFD numerical simulation results. The results show that the area division method, airflow pattern, airflow state of occupied zone and the heat source affect C_b value.