王立舒, 梁秋艳, 李琳, 丁修增, 唐丽静. 聚光太阳能温差发电装置性能分析与试验[J]. 农业工程学报, 2015, 31(24): 64-71. DOI: 10.11975/j.issn.1002-6819.2015.24.010
    引用本文: 王立舒, 梁秋艳, 李琳, 丁修增, 唐丽静. 聚光太阳能温差发电装置性能分析与试验[J]. 农业工程学报, 2015, 31(24): 64-71. DOI: 10.11975/j.issn.1002-6819.2015.24.010
    Wang Lishu, Liang Qiuyan, Li Lin, Ding Xiuzeng, Tang Lijing. Performance analysis and test on concentration solar thermoelectric generation device[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2015, 31(24): 64-71. DOI: 10.11975/j.issn.1002-6819.2015.24.010
    Citation: Wang Lishu, Liang Qiuyan, Li Lin, Ding Xiuzeng, Tang Lijing. Performance analysis and test on concentration solar thermoelectric generation device[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2015, 31(24): 64-71. DOI: 10.11975/j.issn.1002-6819.2015.24.010

    聚光太阳能温差发电装置性能分析与试验

    Performance analysis and test on concentration solar thermoelectric generation device

    • 摘要: 为提高太阳能温差发电装置的热电转换效率,该文设计聚光太阳能温差发电装置,利用槽式抛物面反射聚光镜进行聚光,经集热体转换为热能后提高温差发电器(thermoelectric generator,TEG)热端温度,冷端采用扁平热管作为传热元件,利用水冷散热,增大TEG冷热端温差,提高装置输出功率及热电转换效率。对装置建立能量转换平衡方程,通过数值计算分析不同太阳辐射强度对热损失、光热转换效率及热电转换效率的影响。为解决多个热电模块串联在一起,无法使每个模块都工作在最大功率输出状态,从而导致整体输出功率降低的问题,采用集中-分布混合式最大功率跟踪(maximum power point tracking,MPPT),试验结果表明,经过MPPT后装置能很快达到最大功率输出点,且输出功率稳定,运行30 min输出功率增加3.2 W。搭建了装置的性能测试平台,对基于槽式抛物面反射聚光与扁平热管水冷散热的聚光太阳能温差发电装置进行试验研究,结果表明,随着冷却水流量的增加装置输出功率得到提高,当冷却水流量达到8 L/min后,输出功率趋于平缓;随着温差的增大装置的最佳匹配负载逐渐增加。装置的全天性能试验表明,试验期间装置最大输出功率为30.1 W,平均输出功率27.8 W,试验期间发出电量222.4 W·h,热电转换效率最大为5.4%,装置最大效率4.1%,该装置在远程传感器供电和微功耗供电等领域具有广阔的应用前景。

       

      Abstract: Abstract: Due to environmental and energy security concerns, many researches are being conducted in harvesting the energy of the sun. Thermoelectric is one material which generates a voltage in the presence of a temperature gradient. When these materials are sandwiched between a solar absorber and a heat sink to establish a temperature difference and generate power, they are called solar thermoelectric generators (STEGs), converting solar power to electric power. In this paper, we conducted performance analysis and testing of a concentration solar thermoelectric generation device based on thermoelectric generator (TEG). The device included an electrical generating unit with 10 serially connected thermoelectric modules using a traditional semiconductor material, Bi2Te3. The semiconductor was illuminated by concentrated solar radiation on hot side and cooled by running water through flat heat pipe on the cold side with the condensation of the heat pipe in water tank and the evaporation of the heat pipe connected with the cold side of TEG. A sun-tracking parabolic trough concentrators was used to concentrate solar radiation. Its orientation towards the sun was achieved with a stepper motor. In order to express the performance of concentration solar thermoelectric power generation system accurately, a comprehensive energy transfer model was established, the simulation results showed that when the ambient temperature were constants, the increases of solar irradiance making the solar-thermal conversion efficiency dropped from 58.86% to 54.94%, but thermoelectric conversion efficiency was enhanced from 1.17% to 6.15%. Under the influence of processing technology and materials, even if the same type of thermoelectric modules under the same temperature difference, open circuit voltage and internal resistance were different. When in series with 10 modules, the temperature at the hot side of thermoelectric modules were different spatially due to uniformed heat flow. fl At the same time, due to effect of peltier the temperature of the modules changed along with the different of output power, these factors would lead to different output characteristic of each thermoelectric module. When multiple modules were in series together, it can't make each module working at maximum power output state, resulting in the overall electric energy production reduced. In this research, we used centralized-distributed-hybrid MPPT (Maximum Power Point Tracking) control scheme to overcome the maximum power points mismatching among different thermoelectric generator modules and maximized the energy efficiency of the device. The results of tests showed that the output power of TEG with MPPT was achieved fast, accurately and steadily, and in 30 minutes working time the average power added 3.2 W. In addition, we determined the influence of water flow quantity and optimal load for the performance. The results showed that when flow quantity was less than 8 L/min, temperature of heat pipe condensation and TEG cold side were drop rapidly. But when the flow quantity was greater than 8 L/min, the temperature change was flat out. Output power was rising along with the increase of temperature difference. The maximum power was 30.2 W. The optimal match load was near resistance when temperature difference was low. The optimal load increases gradually along with the increase of temperature difference. The optimal load resistance was 38 Ω with temperature difference of 150 K. Whole day tests for the device have done during the 08:00-16:00 on June 16, 2015, from which the output power smoothly changing and it was between 22.8-30.1 W. With eight-hour test, the average power was 27.8 W, and the electric quantity was 222.4 W?h. The thermoelectric conversion efficiency was up to 5.4% and the maximum efficiency of the device was 4.1%. These test results were consistent with theoretical model analysis. The concentration solar thermoelectric generation device is solid-state device, it has no moving parts, which increases reliability and reduces maintenance. It has many applications such as rural electrification in developing countries and power supply for remote sensors.

       

    /

    返回文章
    返回