5-kW級聚光型太陽追蹤器結構變形與追日偏差分析; Analysis of Structural Deformation and Concentrator Misalignment in a 5-kW Solar Tracker

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Title:	5-kW級聚光型太陽追蹤器結構變形與追日偏差分析;Analysis of Structural Deformation and Concentrator Misalignment in a 5-kW Solar Tracker
Authors:	劉彥佑;Yan-you Liu
Contributors:	機械工程研究所
Keywords:	聚光型太陽能發電系統;追日偏差;太陽追蹤器;HCPV;misalignment;solar tracker
Date:	2010-07-21
Issue Date:	2010-12-08 13:44:02 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究主旨在利用有限元素分析法(FEA)，探討一個5-kW級聚光型太陽光電系統之太陽追蹤器在受到重力及風力作用下運作，其結構變形和聚光模組的追日偏差量。分析的條件分別為無風之情況，以及在風速為7 m/s、12 m/s和37.5 m/s之情況，在每個風速作用下又各別分為風從聚光模組陣列的正面吹來和背面吹來二種風向。此外，本研究還對此太陽追蹤器反覆在不同追日角度下運作，估算其疲勞壽命。藉由量測此太陽追蹤器某些位置在實際操作情況下之應變變化，與模擬結果作比對，可驗證本研究所建立的有限元素分析模型之有效性。比對結果顯示，模擬結果之應變改變趨勢和實驗結果一致，此一致性證實本研究所建立之有限元素分析模型之有效性，可適用於分析聚光型太陽光電系統之結構變形。根據von Mises準則，模擬結果顯示此太陽追蹤器在受到重力加上風速為7 m/s或12 m/s的作用下，各個零件中將不會有結構永久變形之情形發生。然而，在風速為37.5 m/s的作用下，此太陽追蹤器在某些追日角度下，某些零件中的最大應力值將大於其降伏應力，因此預期這些零件將會發生結構破損（塑性變形）。模擬結果顯示此追蹤器在不同追日角度下，聚光透鏡的追日偏差量的變化趨勢與其總位移大小的變化趨勢一致。因此，藉由找到擁有較大總位移的聚光透鏡，即可找到產生較大追日偏差量的聚光透鏡。除了在風速為37.5 m/s的作用下，在其他所有分析情況中，聚光透鏡在風速為12 m/s從聚光模組陣列的正面吹來的情況下會有最大的追日偏差量，其值為0.3度。此數值小於此聚光模組的可接受角度0.4度，所以預期此太陽追蹤器在風速為12 m/s的作用下仍可以正常運作，不會有明顯的發電效率下降。對此太陽追蹤器所估算的疲勞壽命為5.8 × 10的10次方天，因此預期本研究所分析之太陽追蹤器在正常的循環操作下不會發生結構破損之情形。 The purpose of this study is using finite element analysis (FEA) to investigate the effects of gravity and wind loads on the structural deformation and concentrator misalignment in a 5-kW high concentrated photovoltaic (HCPV) system. Several operation conditions, including no wind and wind speeds of 7, 12, and 37.5 m/s blowing to the front side and back side of concentrator arrays, were applied to simulate the stress distribution and structural deformation in the given solar tracker. The concentrator misalignment caused by the structural deformation was also calculated. An estimation of fatigue life was made for the given solar tracker under cyclic operation. A comparison of the simulation and measurement results of strain change at two selected locations in the given solar tracker during field operation was made to validate the constructed FEA model. A reasonable agreement of the simulation and measurement results was found such that the constructed FEA model was validated to be effective in assessment of the structural integrity of an HCPV system. No structural failure was predicted for all the components in the given solar tracker under the loading conditions of gravity alone and plus a wind speed of 7 or 12 m/s according to the von Mises failure criterion. However, the von Mises equivalent stress in some components of the given solar tracker was larger than the yield stress at some zenith angles for a wind speed of 37.5 m/s such that a structural failure (plastic deformation) was predicted. An agreement in the trend of variation of misalignment and resultant displacement of Fresnel lens in each concentrator was found. Therefore, the concentrator with a greater misalignment could be readily identified from the corresponding displacement distribution. Given the conditions of no wind and wind speeds of 7 and 12 m/s, the maximum concentrator misalignment was 0.3 degree for a wind speed of 12 m/s blowing to the front side of concentrator arrays and it was within the range of an acceptance angle of 0.4 degree for the given concentrator. An estimation of fatigue life for the given solar tracker is 5.8 × 10 to the power of 10 days under a wind speed of 12 m/s. In this regard, no fatigue failure was predicted for the given solar tracker under a normally cyclic operation condition.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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