Cascade Energy Use of Chilled Water for Air-Conditioning

Abstract

To achieve cascade energy use, chilled water is used for air-conditioning more than once and multiple heat loads are processed by connecting air conditioners in series. This method is expected to reduce the energy required for air-conditioning energy. Before this study, cascade energy use between two air conditioners was examined in a building. Experimental results showed that heat load cannot be processed properly at the second air conditioner because water flow rates are reduced at the first air conditioner. In this paper, we consider a system to process heat load properly and introduce the effect of cascade energy use. Through some simulations, we propose two systems in which the number of coil rows is selected and chilled water is distributed to the first and second coils, respectively. It is shown that room temperature is properly maintained with both systems, but the room temperature occasionally rises and falls in the former system. It is also shown that the latter system can conserve pump energy, while the former system increases pump energy, compared to a discrete heat source system.