Developement of a Test Procedure for Testing the Thermal Performance of a Thermosyphon-type Solar Domestic Water Heating System
Satishchandra Vasudeo Joshi, Ph.D, 05
Supervisor(s): J. K. Nayak
Testing of solar water heating system is very important from the point of view of comparing and selecting one for a given application. Outdoor testing is still widely used for this purpose and a number of standards have been developed. This work focuses on thermosyphon solar domestic hot water system (TSDHWS). An extensive literature review has been carried out from the development to the implementation of such standards. It is seen that a relative comparative assessment of test standards at a common test facility has not been reported. In this report, qualitative comparisons of these procedures have been presented. Solar-only standards are extensively evaluated experimentally to study their merits and limitations. It is found that the operating conditions for some standards are stringent and would require long test periods. A new, comprehensive and complete test procedure was developed. Three characterising parameters, namely (i) the characteristic system efficiency (ii)solar loss coefficient and (iii) night loss coefficient explained the full day behaviour of TSDHWS. The first two parameters reflect the performance during energy collection phase while third expresses the energy retention capability. A seven hour test period makes the testing possible at all sites in India. A half hour sampling rate was found adequate for measurement and data acquisition. Test results were repeatable and not sensitive to measurement errors. Performance of a TSDHWS at one test place over 10 days can predict its performance in any month of the year at any of the representative test places studied. Thus the new method is simple and applicable to a variety of TSDHWS. It can be considered for adopting as a standard procedure.