A solar water heater with a built-in latent heat storage

In this paper, we have investigated the performance of a novel built-in storage type water heater containing a layer of PCM-filled capsules at the bottom. The PCM layer is introduced with a view of getting hot water during off-sunshine hours. The moving solid-liquid boundary layer problem for the PCM material is simplified to a stationary boundary layer problem, and the effect of latent heat is included in the specific heat by replacing the semi-melted PCM by a fictitious solid. The performance of the water heater is then predicted analytically for two depths of PCM and for different flow rates, both constant and intermittent. The case of sudden withdrawal of water over very short periods is also studied.