SET Proceedings 2978-4387 Caravel Press 10.65582/set.2006.057 2006.057 Improving performance of solar water heater with natural circulation by the unflow riser TecharungpaisanP. tec_pisit@yahoo.com TeeboonmaU. Mechanical Engineering Department, Faculty of Engineering, Ubon Ratchathani University, Ubon Ratchathani, Thailand 30082006 5 978-88-89884-05-8 1 6 30 August 2006 © 2006 Copyright WSSET 2006

A thermosyphon domestic solar water heater with horizontal tank is widely used in Thailand. However its performance is still low and should be improved. This paper compared the manufacturer’s original commercial system with the modify system by installing the valve at one riser. This valve was only 10% open during the test. The experimental results reveal the temperature distribution at absorber plate, the water temperature distribution in each riser, water flow rate in each riser and the water temperature distribution in the storage tank. The system performance is increased from 33.9% to 45.45%. The results show that temperature distribution at the absorber plate depends on the water flow rate in each riser. If one riser has low flow, the water temperature and temperature at the absorber plate at that riser and adjacent riser will be high. This provides evidence that the system performance is improved.

 Flow distribution Natural circulation Temperature distribution Solar water heater Unflow riser 30 August to 1 September 2006 5th International Conference on Sustainable Energy Technologies SET2006 5 Vicenza, Italy