Study On The Performance Characteristics Of Trough - Type Condensed Solar Heating System

Solar photovoltaic power generation is one of the most popular renewableenergy utilization way. The extraction process of photovoltaic materials not onlyconsumes a lot of energy, but also produces environmental pollution. therefore,reducing the use of photovoltaic has a positive meaning. Though concentrator PV/Tsystem is a device that use concentrator mirror instead of the photovoltaic, which notonly can reduce the use of photovoltaic, still can obtain extra heat. But there are someshortcomings on the output performance of though concentrator PV/T system.Though concentrator two cavities for PV/T system is basis of though concentratorPV/T system, the method is: a metal black cavity is connected to the backend ofthough concentrator PV/T system, and circulation system is improved. Aims to: theelectric efficiency and thermal efficiency of the system is improved, and at the sametime the quality of thermal energy output of the system is also improved. Thefollowing research work be done for the performance study of the system:(1)Measured method of the though concentrator illumination density with CCDindustrial camera is introduced abundantly in this paper, and parameterized modelinganalysis is used through mathematical statistical method for concentratingillumination density characteristic. four parameters of the concentrator illuminationdensity is summed up: average illuminate value, degree of non-uniform, peakdeviation degree and illuminate utilization ratio, etc. Illumination parameters as tosolve the matching problem of concentrated illumination density and performance ofconcentrator photovoltaic array provides a new reference.(2)The double exponential equivalent circuit model of the back contact solar cellarray is acquired by introducing recombination mechanism and parasitic resistance ofthe cell under the concentrated sunlight, which the simulation results agree well withthe experimental records, and the error is within7.5%. Model provides a theoreticalbasis for the output performance research of concentrator photovoltaic.(3)Under the condition of the concentrator, the binary sections of non-uniform illumination is designed as the infinitesimal of concentrated illumination densitydistribution. the results can verify the illumination non-uniformity effect on outputcharacteristic of photovoltaic array, which has nothing to do with the shape ofdistribution; Qualitative analysis at the same time under the different condition ofbinary sections of non-uniform illumination is performed for non-uniform degreeparameter influence on the output characteristic of photovoltaic array. The reliabilityof illumination non-uniformity parameters can determine characteristic parameters ofphotovoltaic array(4)The results show that the short circuit current and the relative maximum powerincrease with the increase of the relative average illuminate value, and the degree ofincrease is little smaller due to the intensifying of the recombination mechanismsand the increase of the ohmic losses for parasitic resistance, respectively. The opencircuit voltage decreases with the increase of the non-uniform illumination degreeand the peak deviation degree. The relative average illuminate value has a greatestinfluence on the fill factor because of the ohmic losses for parasitic resistance. Theconversion efficiency of solar cell depends on the illuminate utilization ratio and therelative average illuminate value. Synthetically evaluated the performance of theilluminate parameters, it can be conclude that, when the opening width of mirror is157cm and the distance from focal plane is2cm, such illuminate distribution ismore suitable for the performance output of the back contact solar cell array.(5)In three different photovoltaic (concentrated silicon cell, space silicon cell andgallium arsenide cell) array as the output component of though concentrator twocavity for PV/T system and the though concentrated PV/T system, and the analysisof the each cell array under the condition of two sets of electrical and thermalperformance of the system. The results show that the average electric power outputand average cell array electric efficiency of the two cavities for PV/T system is moreeffective than PV/T system; the system average thermal efficiency of three cell arraybased on two cavities for PV/T system is increased by45.67%,45.67%and24.32%respectively, the temperature of the working medium water in water tank isrespectively increased by19.81℃,17.13℃and22.41℃. The system has beenconsiderable improvement in the thermal quality, which can satisfy the requirement of living hot water supply.(6)From the perspective of the energy utilization rate of the two cavities for economicperformance of PV/T system is superior to the tablet photovoltaic power generationsystem, but less than water heater.In this paper, the conclusion can regard as the experimental support andtheoretical basis is provided for the further development of the groove typecondenser electric heating system and application...