| Solar energy is clean,environmental and renewable.The development and utilization of solar energy can not only solve the problem of air pollution but also cope with the problem of energy shortage in the future.For the solar photovoltaic(PV)utilization,the approach of solar concentration is usually employed to reduce the cost.But the high solar concentration non-uniformity caused by traditional solar concentrators leads to the efficiency decrease of solar cells.In addition,each type of solar cell has a certain spectral response range.The invalid solar radiation will increase the cell temperature and thus decrease the photo-electric transmission efficiency of solar cells.Aiming at the above problems and based on the traditional solar PV/Thermal systems,this paper has launched the following works.Firstly,a novel solar concentration PV and thermal(CPVT)combined system using the multi-segment mirror concentrator and beam filter is proposed.The working principle and design approach of this CPVT combined system are given.This system has a relatively higher solar concentration uniformity and a compact concentrator structure.Considering the monocrystalline silicon cell as the target,the spectral beam splitter(SBS)for this CPVT combined system is designed by using the Needle approach and a coating system structure,which has the relatively better performance,is obtained.The results indicate that for the spectral range of 250.0?2500.0 nm,the average transmittance and reflectance of the designed SBS are 72.1%and 27.9%.Secondly,the Monte Carlo Ray Tracing approach is used to simulate the solar concentrating process of the CPVT combined system.The solar concentration performances on PV panel and thermal receiver tube surfaces are obtained.The results are demonstrate that the solar concentrating uniformity on PV panels are relatively higher and the thermal receiver tube has a symmetrical double-peak distribution of energy flux density.The influence of sun-tracking error on the optical performance of the CPVT combined system is evaluated.The results show that the overall optical efficiency of the system can be greater than 69.6%when the sun-tracking error is less than 1.0°.The relationships between key structural and optical parameters are calculated and analyzed.The interactional laws of structural parameters as well as the interactional laws of structural and optical parameters are obtained.The influence analysis results of the structural parameters of the thermal receiver tube reveal that an optimal installation height exists,which can lead to the maximum optical efficiency of the thermal utilization sub-system.Finally,the thermodynamic analysis of the CPVT combined system is conducted.The formulas of key power and efficiency parameters are derived and obtained.The analysis results demonstrate that the total output power of the CPVT combined system is 2390.6 W,and the PV transmission and overall energy efficiencies of the system are 30.5%and 26.6%,which are all higher than those of the solar CPV system under the same condition.The influence of the operating temperature of the thermal receiver tube on the thermodynamic performance is evaluated.The results reveal that with the operating temperature of the thermal receiver tube increased,the total output power and overall energy efficiency of the CPVT combined system both increase first and then decrease.The optimal operating temperature of the thermal receiver tube exists,which can lead to the maximum total output power of the CPVT combined system. |
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