In a typical parabolic trough collector(PTC), sunlight is concentrated at the bottom of the absorber tube. This concentrated solar flux leads to uneven heat distribution, resulting in high local temperatures and signi...In a typical parabolic trough collector(PTC), sunlight is concentrated at the bottom of the absorber tube. This concentrated solar flux leads to uneven heat distribution, resulting in high local temperatures and significant thermal stress on the absorber tube.These limitations have restricted the application of PTCs in solar thermochemistry and other fields and have impacted their safe operation. In this study, a new PTC with dual planar mirrors(DPMS) is proposed to homogenize the circumferential solar flux distribution of the absorber tube. A design method and single-objective optimization of the new PTC with a DPMS are proposed,and an uncertainty analysis of the operational and structural parameters is performed. A coupled light-heat-structure numerical model was developed to study the heat transfer performance and structural mechanical properties. The thermodynamic properties of the PTC with DPMS under different boundary conditions were analyzed. The results show that the circumferential temperature difference of the new PTC is within 2.6 K, and the circumferential thermal deformation is within 0.9 mm under typical working conditions(the inlet velocity of the heat transfer fluid is 3 m/s, inlet temperature is 573.15 K, and the direct normal irradiance is 1000 W/m^(2)). Compared with conventional PTCs, the circumferential temperature difference is reduced by 74%–90%, and the maximum thermal deformation along the y-axis is reduced by more than 95% under all working conditions(1–5 m/s, 373.5–675.15 K, 200–1000 W/m^(2)). The new PTC maintains the uniformity of the circumferential solar flux distribution for different operating parameters(sun incident angle of 0°–3°) and installation errors(±3 mm), is suitable for solar energy applications in various fields, and has the potential for large-scale applications.展开更多
Concentrating solar power technology is one of the most promising alternative energy technologies.In recent past,Linear Fresnel Reflector systems have received great attention and novel designs have been proposed keep...Concentrating solar power technology is one of the most promising alternative energy technologies.In recent past,Linear Fresnel Reflector systems have received great attention and novel designs have been proposed keeping in view the objective to enhance its functionality and performance.For achieving the same objective,this study presents a novel concept where a conventional LFR is enclosed in a greenhouse called greenhouse-LFR.It was expected that such an enclosure can:(1)increase the incoming solar radiation,(2)further improve the overall efficiency due to simplified cleaning process and(3)reduce the capital cost for the construction of LFR support system.A complete thermal and optical analysis was presented for modeling and performance evaluation of the solar field of both conventional-LFR and novel greenhouse-LFR.Sets of non-linear equations for each system were solved using Newton-Raphson method.More detailed optical analysis was further performed for conventional-LFR considering the seasonal variations.The results concluded that the greenhouse-LFR is better than the conventional-LFR as it had higher efficiency and useful heat with lesser heat losses.For greenhouse-LFR,the maximum thermal efficiency was 73.2%whereas for conventional-LFR it was 37.2%.Also,there was an average increase of useful heat by 3 times in the month of February and 4.7 times in the month of September.SolTrace^(TM) analysis indicated significant spillage loss when a conventional-LFR was used without a secondary reflector or slight curvature of the mirrors.展开更多
基金supported by the Distinguish Young Scholars of the National Natural Science Foundation of China(Grant No. 52225601)the Major Program of the National Natural Science Foundation of China(Grant No.52090061)。
文摘In a typical parabolic trough collector(PTC), sunlight is concentrated at the bottom of the absorber tube. This concentrated solar flux leads to uneven heat distribution, resulting in high local temperatures and significant thermal stress on the absorber tube.These limitations have restricted the application of PTCs in solar thermochemistry and other fields and have impacted their safe operation. In this study, a new PTC with dual planar mirrors(DPMS) is proposed to homogenize the circumferential solar flux distribution of the absorber tube. A design method and single-objective optimization of the new PTC with a DPMS are proposed,and an uncertainty analysis of the operational and structural parameters is performed. A coupled light-heat-structure numerical model was developed to study the heat transfer performance and structural mechanical properties. The thermodynamic properties of the PTC with DPMS under different boundary conditions were analyzed. The results show that the circumferential temperature difference of the new PTC is within 2.6 K, and the circumferential thermal deformation is within 0.9 mm under typical working conditions(the inlet velocity of the heat transfer fluid is 3 m/s, inlet temperature is 573.15 K, and the direct normal irradiance is 1000 W/m^(2)). Compared with conventional PTCs, the circumferential temperature difference is reduced by 74%–90%, and the maximum thermal deformation along the y-axis is reduced by more than 95% under all working conditions(1–5 m/s, 373.5–675.15 K, 200–1000 W/m^(2)). The new PTC maintains the uniformity of the circumferential solar flux distribution for different operating parameters(sun incident angle of 0°–3°) and installation errors(±3 mm), is suitable for solar energy applications in various fields, and has the potential for large-scale applications.
基金The authors extend their appreciation to the Deputyship for Research&Innovation,“Ministry of Education”in Saudi Arabia for funding this research work through the project number IFKSURG-2020-200.
文摘Concentrating solar power technology is one of the most promising alternative energy technologies.In recent past,Linear Fresnel Reflector systems have received great attention and novel designs have been proposed keeping in view the objective to enhance its functionality and performance.For achieving the same objective,this study presents a novel concept where a conventional LFR is enclosed in a greenhouse called greenhouse-LFR.It was expected that such an enclosure can:(1)increase the incoming solar radiation,(2)further improve the overall efficiency due to simplified cleaning process and(3)reduce the capital cost for the construction of LFR support system.A complete thermal and optical analysis was presented for modeling and performance evaluation of the solar field of both conventional-LFR and novel greenhouse-LFR.Sets of non-linear equations for each system were solved using Newton-Raphson method.More detailed optical analysis was further performed for conventional-LFR considering the seasonal variations.The results concluded that the greenhouse-LFR is better than the conventional-LFR as it had higher efficiency and useful heat with lesser heat losses.For greenhouse-LFR,the maximum thermal efficiency was 73.2%whereas for conventional-LFR it was 37.2%.Also,there was an average increase of useful heat by 3 times in the month of February and 4.7 times in the month of September.SolTrace^(TM) analysis indicated significant spillage loss when a conventional-LFR was used without a secondary reflector or slight curvature of the mirrors.
