Experimental study of evacuated-tube solar water heaters in Hong Kong

Abstract

The evacuated tube solar water heaters are widely in use today. But so far their thermal performance has not been systematically evaluated, despite the increased popularity. An experimental solar hot water system including two collector types, namely water-in-glass and heat-pipe, of evacuated tube solar water heater has been set up. Their capacity is typical for serving single family domestic hot water system. Performance tests were carried out in Hong Kong and under almost identical boundary conditions by placing the two collectors side-by-side. The energy performance has been analysed and the daily efficiency, transient efficiency and night-time heat loss were compared. While the energy acquisition performance of the heat-pipe collector design is found slightly better, the heat loss performance is found weaker than the water-in-glass collector design.

Thermal Performance Characterization of Evacuated Tube Collector Solar Water Heater with Constant Inlet Water Temperature

“…As a result, ETCs of heat pipe type were better performed and has around 20 % higher efficiency than ET Collectors without heat pipe. T-T Chow [21] also studied and analysed experimentally the comparison of heat pipe & water in glass type of ET Collectors in Hong Kong. The research present heat loss at night, daily thermal efficiency, transient efficiency, and comparison of these collectors.…”