Effective heat utilization of diurnal range of atmospheric temperature with stratified thermal energy storage system

Behavior of a system using the diurnal range of atmosphere temperature in the summer is characterized by numerical simulation. The proposed system consists of a radiator, a thermal energy storage tank, and a fan-coil cooler. The storage tank is fully stratified. The performance of the system is compared with the case when the storage tank is fully mixed. Parameters for the calculation are assumed from the actual weather and characteristics of the appliances in Japan. Total consumption of electric power is used for evaluating the system performance. From the calculation, it is found that there are optimum conditions to decrease the consumption of electric power as well as the case of mixed tank system. When the radiator is operated during some limited hours, the total consumption of electric power becomes smaller than that when the radiator is continuously operated all night. The consumption decreases as the capacity of the thermal energy storage tank increases. There are also most effective conditions in the flow state of the pumps and the operating temperature of the fan-coil cooler. With a stratified tank, the total consumption of electric power is decreased in the maximum by about 3% compared with mixed one. This system has a possibility to save energy or make the uneven consumption of electric power uniform throughout a 24-hour period.