Abstract

In this paper an experimental study of different design of solar water heaters
was carried out. all the used solar water heaters work on the thermosiphone theory.
The experimental study includes testing of four solar water heaters. The first one is
a Evacuated tube solar heater flat produced by Denka-China. The second one is a
flat plate solar water heater produced by the general company for electrical
industries/Baghdad, it's in working since 2001 and it was used for testing after
simple maintenance. The third one is a flat plate solar water heater produced by
solar energy research center/Baghdad, which is in work in 2007, it is similar to the
first one but with some differences in design and material . The last one is a
portable type - solar water heater.
The testing was done for a period of time from February to July 2007. The
performance was tested of the collectors with no load conditions and with different
rate of load conditions. The no load testing results showed that performance for the
solar water heater produced by Denka Company is better than other solar water
heaters. The flat plate solar water heater produced by solar energy research center
have good performance and it’s the nearest to the performance of a Evacuated tube solar heaters from otheres heaters. Water withdraw results show an improvement in
daily efficiency for the four solar water heaters, where the efficiency of
solar water heaters is (55% - 66%) for the first heater, (48% - 57%) for the second
heater, (51% - 62%) for the third heater and (20% - 35%) for the fourth heater.