solar hybrid domestic hot water system; rockbed air heater; shell-and-tube heat; water storage tank
This article describes the results of a simulation study of a forced-circulation solar hybrid domestic hot water system (SHDHW) that circulates air through a rockbed air heater and employs an external air-to-water, transverse fin, shell-and-tube heat exchanger to transfer heat from the air to the water. To satisfy the hot water demand, no auxiliary energy has been supplied to the system. The system performance has been evaluated for a typical cold climate of Delhi, India, and corresponds to the hot water demand of a four-person residential building. In addition to estimating the temperatures of the different components, the study has been extended to compute the pumping power expended in air and water circulation throughout the system in order to estimate the effective energy stored in the water storage tank and the rock bed for reuse during the next instants of operation.