温室聚光光伏/温差联合发电系统的设计与性能试验

为解决温室常规能源供电能耗大及太阳能供电模式利用效率低的问题,该文根据温室特点设计了CPC(compound parabolic concentrator)型聚光光伏/温差联合发电系统,利用CPC型聚光器进行聚光,建立光伏、温差联合发电模式,采用扁平热管作为传热元件,利用水对流给系统冷却。为测试温室聚光光伏/温差联合发电系统性能,对系统的能量转换进行了分析,分析不同光辐射强度、冷却水流量对系统的影响。同时搭建了系统的试验平台,对水冷扁平热管型CPC-PV/TE联合发电系统(compound parabolic concentrator-photovoltaic/thermoelectric hybrid power generation system,CPC-PV/TE)进行试验研究,结果表明,系统联合发电效率大于单独一种发电方式的效率,实现能源的梯级利用。在CPC-PV/TE联合发电系统瞬时性能的试验期间联合效率最大可达到20.06%,发电功率最大值为125.98 W。在全天性能测试期间,CPC-PV/TE联合发电系统全天的发电效率在18.57%以上,CPC-PV/TE联合发电系统发电性能优于已有的联合发电系统,所获得的电能基本满足寒地温室内环境监控系统、照明系统的供电要求。

Design and performance test of CPC-PV/TE hybrid power generation system in greenhouse

Abstract: With the rapid development of agricultural science and technology, various types of environmental testing equipments and production facilities consume a lot of energy in greenhouse. Therefore, it is important to design a high-efficiency greenhouse power supply device. At the same time, the energy crisis in the 21st century and the air pollution caused by burning of fossil fuels become serious. It can not wait to solve the environmental pollution. Therefore, increasing the development and utilization of solar energy is imminent. Solar energy is a kind of clean and renewable energy, and the study of solar energy development and utilization has become a hot issue nowadays, but in general, its efficiency is low. In order to solve the problem of large fossil energy consumption in the greenhouse and the current inefficient use of solar energy, compound parabolic concentrator-photovoltaic / thermoelectric hybrid power generation system (CPC-PV/TE) based on the characteristics of greenhouse in Northeast China is proposed in the present paper. A system contains CPC, PV/TE hybrid system and flat heat pipe. CPC converges light to the surface of photovoltaic cells. It enhances light irradiation intensity. Photovoltaic cells use the photovoltaic effect principle to generate electricity. Attached to photovoltaic cells, thermoelectric power generator modules convert the excess heat generated by photovoltaic cells power generation to electricity power simultaneously. Flat heat pipe is used as heat transfer element, and then a certain amount of water is used to effectively transfer the rest of the heat. In order to express the performance of CPC-PV/TE hybrid power generation system accurately, a comprehensive energy transfer model has been established, and the efficiency of CPC-PV/TE hybrid system and PV or TE module alone under different levels of irradiation and various water flows has been discussed. The results show that the faster the cooling water flows, the higher the generated power by CPC-PV/TE hybrid system is, but there is a limit. The efficiency of CPC-PV/TE hybrid system is greater than the PV or TE module alone. Moreover, experimental test system has been built, and a series of experimental researches have been done on CPC-PV/TE hybrid system with water-cooled flat heat pipe in greenhouse of Northeast Agricultural University. As a result, in transient experimental research, photovoltaic power generation accounts for a large proportion, so variation tendency of generated power by CPC-PV/TE system is similar to photovoltaic. For thermoelectric power generation modules join in the CPC-PV/TE hybrid system, the generated power and the efficiency of CPC-PV/TE hybrid system increase; it gains the maximum power output of 125.98 W, and the efficiency gets to 20.06%. A cascade utilization of solar energy is achieved, and then its utilization is improved. From April 7, 2015 to April 11, 2015, the daily performance of CPC-PV/TE hybrid system has been evaluated, and the generated power of CPC-PV/TE hybrid system varies from 2.35 to 3.24 MJ. The efficiency of CPC-PV/TE hybrid system in these days is more than 18.57%, and the highest value is 19.15%. CPC-PV/TE hybrid system is superior to existing PV/TE system. More importantly, CPC-PV/TE hybrid system basically meets the power requirements of the greenhouse environment monitoring systems and lighting equipments. It has a greater advantage in the field of solar energy comprehensive utilization.