THE EFFECT OF UPPER-HEATING SYSTEM IN SOLAR WATER STORAGE TANK

Thermal stratification in the water storage tank of solar heating system is essential to increase the collection efficiency. We previously investigated the stratification performance of side-heating system, where the hot water returning from the collector heats up the side wall of storage tank. Subsequently, we studied an evolved heating system for further improvement, where we added an upper-heating to the side-heating. Here we thoroughly examine the stratification performance of the evolved heating system using TRNSYS-based simulation. As the essential result, contrary to expectation, evolved system does not show substantial improvement of collection efficiency compared to side-heating. However, we confirm that evolved system excels in the useful energy.