Performance investigation of convective and radiant heat removal methods in large spaces

Abstract

Reducing the energy used for removing heat from solar radiation, high-temperature walls and air infiltration is becoming increasingly important in large space buildings. This paper proposes an analysis method to distinguish the performances of different heat removal methods in raising the cooling efficiency as well as reducing the heat flux. Firstly, the features of heat sources in large spaces are identified and proper parameters (heat flux or temperature) are selected to reflect their characteristics in heat transfer. Based on the goals of maximizing the cooling temperature and minimizing the heat flux, the influencing coefficients are defined to evaluate the influences or active forces of each type heat source and removal method on indoor environment and heat flux, and a simplified analysis model is established to reflect the character of different heat removal processes in large spaces with equivalent thermal resistance. On this basis, the influences of heat sources on indoor environment and the active forces of heat removal methods (e.g., jet ventilation and radiant floor cooling) are weighted quantitatively. By comparison, when the radiant floor cooling method is adopted, the operative temperature influencing coefficients that correspond to solar radiation and high-temperature envelope are lower than those in the case of jet ventilation, and the heat flux influencing coefficients are also smaller due to relatively lower degree of vertical air mixing. Therefore, radiant floor cooling method is more suitable for large spaces for its specialty in handling the heat from solar radiation and high-temperature envelope.