Energy Conversion and Management, Vol.42, No.11, 1379-1399, 2001
Development and performance analysis of compound parabolic solar concentrators with reduced gap losses - oversized reflector
A severe energy shortage already exists in many parts of the developing world. In an attempt to find a technical solution, several solar energy collection technologies have been developed. A system has been designed to use compound parabolic concentrating collectors to collect solar energy and to generate steam. A compound parabolic concentrator (CPC) profile with oversized reflector and thereby reduced gap losses was designed with a half-acceptance angle of 23.5 degrees for a tubular absorber of OD 19 mm. Five troughs fabricated with a fiberglass substrate pasted over with UV stabilized self-adhesive aluminized polyester foil having high specular reflectivity joined together side by side make the CPC module with aperture area of 0.72 m(2). Copper tubes coated with NALSUN selective coatings and enclosed by borosilicate glass envelopes act as absorbers. The reflector-absorber assembly placed in a single glazed glass wool insulated wooden box forms the CPC collector. Using water as heat transfer fluid, efficiency tests were conducted with different inlet temperatures. Even at high temperature, the system operates with a reasonably high efficiency of 50%. In situ steam generation testing was also conducted. The fabricated CPC collector was used for steam cooking by connecting it to a pressure cooker. Cooking tests were conducted and the results are compared with earlier works. This cooker unites the characteristics of reflector cookers, steam cookers, pressure cookers and heat accumulating solar cookers. The fabricated CPC can be of immense and wide spread use for rural applications, such as water heating, steam cooking and sterilization.