严寒地区菲涅尔CPVT系统积尘特性及热电输出性能研究

This project will study the dust accumulation feature and its influence on Fresnel concentrating photovoltaic/thermal system in cold region in order to solve several problems such as the energy loss of the solar concentrators and system performance degradation due to the reduction of Fresnel lens transmittance and variation of mirror radiation characteristics. Based on the owned Fresnel concentrating photovoltaic/thermal system, the simulation and experimentation methods are used to analyze the rules of dust accumulation and their influence on the concentration performance and energy flow distribution of the system in cold region according to the factors including the source of the dust, the formation of the dust accumulation and the amount of the dust in this environmental and climatic condition. The project hopes to obtain the predicting models including dust accumulation and the decay rate of the system output power, and the effect rule of dust accumulation on the thermoelectric output performance, find the efficient dust removing methods and the optimum time of cleaning dust. Finally, the highly-efficient cleaning dust project will be proposed to improve the output performance of the system. Considered the cooperative reaction with many factors such as solar irradiance, environmental and climatic condition, the rule of the dust accumulation, concentrator materials characteristics and operation parameters of microchannel radiator, the dust-irradiance-operation cooperative reaction analyzing method was employed to study the thermoelectric output performance of Fresnel concentrating photovoltaic/thermal system and hope to find the way to improve the photo-thermal and photoelectric conversion efficiency and the total efficiency of the system which is also benefit for applying the Fresnel concentrating photovoltaic/thermal system safety and high-efficiency with theory and experiment data.

针对严寒地区环境气候条件、积尘遮挡和腐蚀等作用下菲涅尔透镜透射率降低，镜面辐射特性改变，造成聚光器能量损失、系统热电输出性能下降等问题，课题基于现有菲涅尔聚光CPVT试验系统，通过理论分析、数值模拟与试验研究相结合的技术路线，基于该地区积尘来源、形成以及积尘量等因素，分析严寒地区积尘规律及其对聚光及能流分布的影响机理，得到积尘量预测模型以及系统输出功率衰减率预测模型，以及积尘对热电输出性能的影响规律，寻找高效除尘方法，分析积尘清洁的最优时间，给出适合该地区气候特征的高效清洁方案，提高系统输出特性；考虑严寒地区太阳辐照、环境气候特点、积尘规律、聚光器材料特性以及微通道散热器运行参数调节等多因子协同作用，采用积尘-辐照-运行调节协同作用分析方法，研究系统热电输出性能，寻找提高系统光电、光热转换与综合效率的方法，为严寒地区风沙积尘环境下菲涅尔聚光CPVT系统的安全高效利用提供提供理论和试验数据。

针对严寒地区环境气候条件、积尘遮挡和腐蚀等作用下菲涅尔透镜透射率降低，镜面辐射特性改变，造成聚光器能量损失、系统热电输出性能下降等问题，基于积尘对镜面反射率影响，建立积尘重叠模型，得到了考虑灰尘覆盖和遮挡的菲涅尔聚光镜面光线入射规律以及对聚光效率的影响机理，建立考虑灰尘积尘密度及周期的自然积尘预测模型；提出基于积尘颗粒形状的临界光学特性，结合灰尘的折射率和消光系数，得到了考虑灰尘形状的菲涅尔聚光镜面透射率预测模型，并进行了试验验证；研究了镜面积尘工况下电池表面能流密度分布规律及影响因素，得到了聚光砷化镓电池温度和除尘周期预测，可预测不同暴露期间，积尘对系统热电输出性能的影响规律；得到了地区季节和气候对菲涅尔透镜表面积尘密度的影响以及聚光镜透射率下降值与积尘密度的关系，并研究了聚光砷化镓电池纳米流体微通道冷却系统特性，制备具有高导热和稳定性的纳米流体换热工质，得到了不同换热工质的热物性变性规律，基于试验数据建立并优化人工神经网络预测模型，获得具有较高精度的预测值，解决了聚光后GaAs电池温度过高，以及积尘导致表面能流分布不均引起的温度不均问题，从而提高CPVT系统的光热、光电转化效率等输出特性。 .项目建立了基于灰尘颗粒的光线透射率衰减函数模型，得到严寒地区菲涅尔聚光系统输出功率衰减率预测、积尘对热电输出性能的影响预测模型，考虑积尘-辐射-冷却-系统运行调节协同作用下，采用定性与定量结合方法对不同季节自然积尘条件下系统光-热-电输出性能进行试验分析，分析积尘工况对HCPVT系统热电输出性能的影响程度，试验研究系统微通道散热器的强化传热特性，解析光学性能-能流分布-热电输出的耦合关系，揭示了积尘工况对CPVT系统输出性能的衰减机理，可直接应用于实际聚光系统清洁频率的预测，得到积尘清洁的最优时间和积尘清洁方案，为开展镜面高效节能除尘机制奠定理论和试验基础。