Design, fabrication and experimental analysis of parabolic trough collector using different reflecting materials for hot water generation

Abstract

In this developing world, energy demand is growing day by day. But due to the scarcity and continuous depletion of conventional fuels, Renewable energy is an alternative source. Among all renewable energies, we have solar energy in abundance. India today has among the world’s largest programs in solar energy. The India Meteorological Department maintains a nationwide network of radiation stations, which measure solar radiation, and also the daily duration of sunshine. In most parts of India, clear sunny weather is experienced 250 to 300 days a year. The 2 annual global radiation varies from 1600 to 2200 kWh/m , which is comparable with radiation received in the tropical and sub-tropical regions. A parabolic trough solar collector uses a mirror in the shape of a parabola to reflect and concentrate sun’s radiations towards a receiver tube located at the focus line of the parabola. In the present dissertation work a Prototype Parabolic Trough Concentrator has been designed , fabricated and experimental analysis is being carried out for its feasibility in hot water generation. A Prototype parabolic Trough Concentrator is fabricated and their efficiency is compared using different reflecting materials like Stainless Steel, Aluminium foil, Glass Mirror. The absorber pipe is a copper tube with appropriate black paint and a glazing (glass cover tube) is provided to minimize the losses and comparing the test results .Water is used as heat carrying fluid in absorber tube. The concentration ratio for PTC is 11.32 with aperture area 1.40 m2(without glazing) and 1.387 m2(with glazing). The maximum temperature of heating water obtained is 81.2 while the average temperature of heating water was produced is 65 . A brief analysis is carried out to choose the best reflective material in terms of improved efficiency. The improvement in efficiency using glass as a reflective material in comparison to stainless steel and aluminium foil obtained 5-40%. The main objective of present study is to design, fabrication, experimental analysis of Prototype PTC with different reflecting materials for hot water generation and to check its feasibility for further practical applications . The results obtained shows that the production of heating water using the sun flux is a viable undertaking. Improvement of tracking system and the optical efficiency can improve the efficiency of fabricated PTC. Reduced mass flow rate or with different mass flow rate efficiency of prototype PTC can further be increased.