The Study On The Optical And Thermal Performance Of Parabolic Trough Collector

Relative energy shortage, low efficiency of the development and the use of energy, and environment pollution caused by the development and the use of energy are becoming main factors which limit the persistent development of the economy and the society of our country. Currently, as far as our whole country is concerned, the low-cost convenient new technology is needed urgently to meet the demands of different areas. Our country covers a very wide field and owns plenty of solar energy. So solar energy should be largely developed and applied in resident daily life so that electricity can be saved and the demand of production and living can be met.Parabolic trough collector(PTC) can concentrate the sunlight on the receiver to heat the working fluid in the receiver, so heat can be got from the working fluid. PTC is widely used in the field of electricity generation, air-conditioning, heating, weaving, paper making, desalination, and so on. In some developed countries, PTC has been applied well, while PTC is seldom seen in developing countries. As high cost and advanced technology are needed in PTC application in developed countries, PTC is hardly researched in our country. In order to apply PTC, we should develop a kind of low-cost applicable PTC according to our current situation of our country. Moreover, as PTC is a facility to make use of solar energy, it is greatly influenced by season and climate. Therefore, the researches in the foreign countries are only as reference for us. The experiments on PTC should be done and the data should be got in our country. Then, we can master more deeply the performance of PTC and decide whether PTC can be applied and how to apply it.This paper discusses the PTC from the aspects of theory and experiment The structure, material choosing, the principles of optics and thermodynamics, the economic analyse of technology, and the application of electricity generation system are all included in the theory. And the temperature of the working fluid, the effect of the different structure of the receiver and the absorbent coatings on the performance of PTC, and the factors related to energy efficiency are studied in the experiments. The experimental results show that the energy output of the PTC equipped with glass tube and the absorbent coatings is 137.69W, the exergy output is 12.72W, the energy efficiency is 21.09%, and the exergy efficiency is 1.95%. The glass tube which envelopes the absorber and the absorbant coatings can both largely reduce heat loss of the receiver and improve the energy and exergy efficiencies of PTC. And the glass tube and theabsorbent coatings are cost-effective. Optical efficiency is the main factor which influences the energy efficiency. If we can greatly improve the mirror reflectance and reduce mirror surface slope errors, optical efficiency will be improved greatly and thus energy efficiency will be improved greatly.