| In the face of the contradiction of China’s energy reserves and huge demand for the future development and persecution of environmental pollutants led by PM2.5 in recent years,actively development and utilization of solar energy and other renewable energy has been an important position in sustainable development strategy.Collector is the key part of solar energy heat utilization system.In the field of low temperature,solar collector has been wildly applied.Otherwise,It is urgent for in need of a collection of high-quality heat energy collector in high temperature field and the compound parabolic concentrator collector(CPC)which because of its high efficient thermal performance is more and more popularThe optical properties and heat transfer characteristics were studied,and the CPC concentrated optical model and heat transfer model of vacuum collector were also established,the research are as the following:(1)On the basis of analyzing the laws of the orbit of the sun and earth,the intensity of solar radiation model is first established,the sun Angle equation parameter of four typical moment a day each year(the declination Angle,Angle,the sun altitude Angle,solar azimuth,solar incidence Angle,etc)was calculated according to the law of the orbit of the sun,and the solar radiation intensity of each time were also calculated,which is to give backing to parameters of the conclusion;(2)Using the monte carlo ray tracing method,the different internal light path diagram and energy flow density distribution in absorber collector were studied respectively.The result indicate that different heat body under the half Angle of incidence on the energy flow density distribution is uneven,it will cause concentration of the heat flow density,and influence the performance of the collector;(3)The heat transfer process of the solar collector was analysied uising the application of heat transfer principle.then the several key factors that affecting the heat transfer performance was carried out on the collector,presenting a mathematical calculation model;(4)By using Fluent software to simulate the heat transfer characteristic of collector,exploring respectively the intensity of solar radiation,annular space pressure,working medium flow rate on the influence of the thermal efficiency of the collector.The result are as following.(1)the solar radiation intensity increased from 500 W/m2 to 900 W/m2,the collection efficiency increased from 53.67% to 81.00%.the stronger of the solar radiation intensity,the higher of the inner surface temperature of the collector.What’s more,the collection efficiency is also increased,but when the solar radiation intensity increases to more than 1000 W/m2,the increaseeffect of collection efficiency is not obvious.(2)the higher pressure in annular space,the greater the heat loss,and with the increase of pressure,the rate of heat loss increase,but when the pressure is under 100 Pa,heat loss variation is not obvious.Oxidation gas in annular space contact with the heat absorbing coating in long time,it will change the emissivity of coating,increase the heat loss,and influence the collection efficiency.(3)collectors collection efficiency increased before leveling off with the increase of import working medium flow rate,and when the working medium flow rate increased to 1.2 m/s,the working medium flow rate has no effect on collectors collection efficiency.(4)when the dip Angle of around 45°,collection efficiency is largest,a reasonable settlement of collector Angle has great impact on the collection efficiency. |
