Effect of tank size on the temperature distributions for solar water heaters

ABSTRACT: The objective of the present study is to investigate the effect of tank size on the temperature distributions as well as the availability of hot water in the storage tanks of solar water heaters with two-stage usage. A usage pattern is assumed, where the first discharge is 50 L of hot water at 7:00 pm (representing two persons taking showers in succession) and the second discharge is 25 L of hot water at 7:00 am (representing one person taking a shower). The standing time between the two draw-offs is fixed at 12 hrs. The investigation is carried out by considering different tank sizes namely: 80 L, 121 L, 150 L and 200 L. TRNSYS program is used for the simulation. Results show that the optimum tank size for solar water heaters is 150 L with high quality solar collectors for the described scenario of the daily hot water usage. Keywords: Temperature distributions, storage tank, hot water, simulation. …………………………………………………………………………………………………………………………