由於人口快速膨脹，能源的需求量大增，但在環境保護與安全的考量下，化石能源與核能發電逐漸受到抵制，因此近代積極的發展再生能源。台灣地處於亞熱帶地區且日照充足，因此太陽能的應用是最具發展潛力的再生能源，近年配合政府對於安裝太陽能熱水器的補助，民眾已開始廣泛使用太陽能熱水器。但台灣地區處於廣大的太平洋區域，平均每年有多達3.4個台風的侵襲，太陽能熱水器易受毀損，因此本研究將利用有限元素軟體ANSYS14.0對太陽能板受風進行結構應力分析。
結果發現，在固定風向的條件下，不同的紊流強度對於太陽能板的受力影響在改變太陽能板對地面的傾斜角度後影響會逐漸消失，而下板面的受力情形會跟隨著傾斜角度的增加而變強。
而在改變風向角的分析中發現到，到達中度颱風的風速40m/s時，在15度、22.5度、30度和135度風向角的太陽能板已經因為局部強烈正、負壓造成不鏽鋼外殼的極大應力產生了破壞，相較許育銘(2013)使用剛性支架的結果要更快達到破壞，且破壞的發生非單一風向角獨有的情況，對比起前人們實驗所得到的結果也更加符合，而為了獲得更詳細的結果，另外使用暫態分析的方法，可以發現和平均壓力所得到的結果趨勢相同，但暫態分析的風壓內因為包含了峰值風壓，因此相較於平均壓力的分析受力要大上許多。

Structure Analysis of Solar Collection under Wind Loading with Various Wind Incidence
Chia-Shan Tsai
Keh-Chin Chang, Kung-Ming Chung
Department of Aeronautics and Astronautics, NCKU

SUMMARY

In light of the extensive damage to solar collectors by the invasion of Typhoons, more information is needed about what affects the construction of solar collectors. This study used ANSYS 14.0 to analyze the destruction of solar collectors with support model and used the wind load measured through experiments. The data were used to demonstrate that the turbulence intensity effect disappears as the tilt angle increases. In different wind incidence cases(i.e. at 15 o, 22.5 o, 30 o, and 135 o of wind incidence), the solar collector faileds due to extreme stress to the stainless steel shell.

Key words: SOLAR COLECTOR, ANSYS, TURBULENCE INTENSITY, WIND INCIDENCE, TRANSIENT ANALYSIS

INTRODUCTION

Rapid population growth has led to a significant increase in the demand for energy, however, due to environmental and safety concerns, fossil fuels and nuclear power have faced increasingly resistance as people look for a modern, positive development of renewable energy. As Taiwan is located in a subtropical regions with abundant sunshine, solar energy offers the most promising renewable energy possibility. In recent years, the government has subsidized the installation of solar water heaters, resulting the population beginning to use solar water heaters more widely. However, Taiwan is in the Pacific region, which is affected by an average of 3.4 typhoons annually. This creates problems as solar water heaters are easily damaged by strong wind loads. This study used finite element software ANSYS14.0 for structural analysis in the study.

METHODS

The method used in the current study is the finite element method, which five main steps. The first, divide the structure or continuum into finite elements. The second step is to formulate the governing equations of each element. In the static analysis, this means building the relationship between nodal loads and the element’s deformation. In the third step, the loads and supports are applied, setting the boundary conditions. Fourth, the governing equations are solved to determine the nodal displacements. Finally, the calculate element strains and stresses are calculated from the nodal displacements.

RESULTS AND DISCUSSION

This study used four models of the tilt angle to explore the effects of turbulence intensity. The deformation of and stress to the stainless steel shell were used to determine that the lower plate of the solar panel was obviously affected by the turbulence intensity. At the 0o wind direction angle, the bottom could not easily form a reflux area. Therefore, when the inclination angle was small, the impact of the turbulence intensity did not disappear. As the tilt angle increased, the effect of turbulence intensity disappeared. On the other side of the solar panel, the upward-facing surface was affected by negative pressure. Therefore, there was no obvious change in the maximum stress beyond the stainless steel casing.
At different wind incidences, when the wind speed reached 40m/s, in some cases the stainless steel shell went beyond the yield strength to the failure criteria. The maximum principal stress in the glass occurred at the wind angle of 180 o. At this angle, glass faced directly into the wind, which pressed the glass down, causing the glass surface to produce the maximum tensile stress. Some others cases also showed large principle stress, 135 o and 30 o. However, regardless of the wind directions, the stress on the glass did not reach a stage that caused damage, so the destruction to the solar collector occurred primarily due to the damage to the stainless steel shell.

CONCLUSION

After analyzing the results, it is found that, as the tilt angle of the solar panel increased, the effect of turbulence intensity was not obvious. Thus, in the analysis of wind incidence cases, the tilt angle is set to 25 o to eliminate the turbulence intensity effect. In addition, when the wind speed reached 40m/s, the solar collector failed due to the extreme stress to the stainless steel shell at wind incidences of 15 o, 22.5 o, 30 o, and 135o. Compared to the results of the rigid support, the present analysis is more consistent with the experimental results.

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