Experimental Study Of High Temperature Flat Plate Solar Collector

High temperature flat-plate solar collector is a new type of solar collector. At the beginning, this paper reviewed the utilization of solar energy as well as the development of solar collectors, at the same time, this paper introduced the development trend of solar collector device in the future. Finally puts forward this research paper.The key technology in the utilization of solar collector is turn radiation energy into heat energy. Due to the solar energy much decentralized, collect the solar energy is the main job. The core component of the solar utilization is solar collectors, it is a special device used to turn the solar radiation energy into heat energy and then transfer heat to working fluid.Since the simple constructer of solar collector and easy maintain as well as environmental friendly. Solar collector is the most mature techonology in utilization of solar collector. The solar collector can be devided into two kinds based on whether have vacuum space which are flat-plate solar collector r and the evacuated solar collector. The evacuated solar collector account for 90% market share,it have many advantages like that the working fluid temperature can reach high temperatures and can runing throughout the year. However, it also has many disadvantages such not under pressure, easy bombing, scaling. Flat-plate solar collector has many advantages like have a simple interface, can working under pressure, have high average efficiency. Meantime, It is also has many disadvantages such as high heat loss, poor thermal insulation properties and the working fluid temperature only reach low temperatures etc. Therefore, flat-plate collector with the increase of domestic technology will inevitably become the development trend of solar collectors.The aim of paper is intended to improve a new flat-plate solar collector, that has high thermal efficiency, high temperature and high quality.This project has established flat-plate solar collector mathematical model in order to provide the theoretical foundation of the thermal performance for itself. Flat-plate solar collector is more complicate than normal sollar collector. It includes three different heat transfer ways which consists of three heat transfer methods:heat conducting, heat convection, radiation heat transfer. This paper will introduce the solar radiatoion, heat loss of solar collector, energy balance of solar collector and flow resistance of collector system. The mathmatical model is helpful for design the solar collector.This paper will be made two flat-plate solar collector, which have different structural dimensions, different cabinet materials and different insulation materials. The two solar collectors are called NO.1 flat-plate solar collector and NO.2 flat-plate solar collector.Then describes the flat-plate solar measurement system's pipeline material, working fluid,insulation materials, and the other components of thermal performance measurement system, such as cooling tank, the oil expansion tank, oil filters, valves, high temperature pump.The experimental data of collector is to assess the solar collector's quality and performance, and provide the basis for the system optimization design. This paper will test the thermal performance of solar collector which includes air drying temperature, instantaneous efficiency and daily average efficiency etc.Firstly, use vacuum glass as the cover of No.1 flat-plate collector, it did air drying experiments.Ten minutes after the experiment, the cover breakdown, indicating that use the glass vacuum as the cover is not feasible。Then, conducting the air drying temperature experiments for NO.1 flat-plate solar collector, its cover is hollow glass. This experiment carried out in a sunny day, the irradiation quantity is 25629 KJ/m2 at that day. The maximum temperature of NO.1 flat-plate solar collector can achieve 170.2℃. And there are no damages of NO.1 flat solar collector after the experiment. And then conduct the test for the two flat-plate collector separately at sunny day of the autumn, The daily average solar radiation intensity for NO.1 flat-plate solar collector are 757W/m2,working fluid mass flow rate are 185Kg/h, in this condition, the maximum temperature of absorber plate for NO.1 flat-plate solar collector is 91.6℃, the maximum working fluid mass flow outlet temperature are 79.5℃. The highest instantaneous efficiency is 0.65, the daily average efficient is 0.54. The No.1 flat-plate collector use double-glazing as the cover.The daily average solar radiation intensity for NO.2 flat-plate solar collector are 989W/m2,working fluid mass flow rate are 85Kg/h, in this condition, the maximum temperature of absorber plate for NO.2 flat-plate solar collector is 98.8℃, the maximum working fluid mass flow outlet temperature are 80.5℃. The highest instantaneous efficiency is 0.55, the daily average efficient is 0.46. By comparison, in a cloudy day, the daily average solar radiation intensity for NO.1 flat solar collector are 612W/m2,working fluid mass flow rate are 148.5Kg/h, in this condition, the maximum temperature of absorber plate for NO.2 flat-plate solar collector is 79.5℃, the maximum working fluid mass flow outlet temperature are 78.8℃. The highest instantaneous efficiency is 0.66, the daily average efficient is 0.51.Experiments shows NO.1 flat-plate solar collector and NO.2 flat-plate solar collector both have better performance than normal flat-plate solar collector, and further on NO.1 flat collector have better performance than NO.2 flat solar collector. Thus, the two flat-plate solar collectors have absolute advantage compare with normal flat solar collector.