DEVELOPMENT OF IMPROVED RECEIVER CAVITY OF A SOLAR THERMAL POWER PLANT

Abstract

The ever increasing urbanisation and industrialisation has led to the increase in demand for energy supply which has imposed a high pressure on the existing conventional energy sources. As these resources are available in limited amount in nature, a situation of energy crisis has occurred. Now, the best possible solution for combating energy crisis is to reduce the dependence on non-renewable energy sources and tap the potential of renewable energy resources. Solar energy is one of such renewable resources which can be used for generation of power either by solar photovoltaic or by solar thermal power plants. The solar thermal power technology is one of the most promising technologies which have achieved rapid development in the world. It has been applied on parabolic trough, linear Fresnel reflector, power tower and parabolic dish. Solar receiver is a photo thermal conversion component of solar thermal power plants, which absorbs solar radiation and heats the working fluid. It plays a very crucial role on the efficiency of the entire power plant, so the design and safety of the receiver is of utmost importance. Among the various designs of existing receivers, one of the designs is of receiver cavity. The receiver cavity consists of a large aperture on the front face of the cavity which provides a benefit of large surface area and low heat loss. Working fluid can attain higher temperature in receiver cavity. This work presents the design, construction and performance investigation of solar receiver cavity in form of tubes for a parabolic trough collector. Experimental tests have been conducted using non-evacuated receiver tube, evacuated receiver tube and modified receiver cavity. Thermal efficiency has been observed in the range of 44-50% and 40-50% with the non-evacuated receiver tube and receiver cavity respectively while with the evacuated receiver tube, the thermal efficiency has been found in the order of 60-70%. Based on the investigations, it has been found that evacuated receiver tube has better thermal efficiency than the other two configurations of receivers investigated for all values of performance parameter, (Ti-Ta)/Hb. Further, it has also been observed that modified receiver cavity has better thermal performance than the non- evacuated receiver tube compared to the values of performance parameter, (Ti-Ta)/Hb, from 0 to 0.09 K.m2/W. However, beyond 0.09 K.m2/W, the non- evacuated receiver tube has been found to be more thermally efficient than the modified receiver cavity.