建筑南立面太阳集热系统应用研究
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摘要
本文利用FLUENT模拟和实验相结合，揭示了太阳能真空集热管在集热状态下的温度场和流场的规律，分析了太阳能真空集热管流场和温度场的影响因素，并分析了内插排挤管对优化垂直安装集热管的集热性能的作用，最后通过实验初步验证了这一方法的有效性。主要研究内容和研究成果如下：
1．根据长期太阳辐射量计算上海地区在6月和12月代表日(6月11日和12月11日)长期平均小时水平面和垂直面上的太阳直射和散射辐射量，并拟合成时间的函数表达式。对于垂直安装的太阳能集热管所接受的太阳辐射，根据晴天太阳辐射模型，利用MatLab编程计算在不同太阳高度角和方位角的情况下，集热管圆周表面的能流分布，并将其拟合成圆周角的函数表达式。
2．通过UDF文件编程，以集热管表面能流分布作为模拟计算的边界条件，使用FLUENT对集热管内的温度场和流场进行了模拟计算。模拟计算的结果表明，在集热管的顶部和中部自然对流换热效果较为明显，但是在集热管的底部则存在着明显的滞流区，降低了整个集热管的集热性能。
3．通过对集热管集热性能的影响因素的分析可知，选择性涂层的吸收率和发射率对集热管的集热性能有较为明显的影响。如何提高选择性涂层的吸收率，降低选择性涂层的发射率，是提高集热管集热性能的关键。此外，通过模拟和实验验证了内插排挤管的方法对抑制集热管内冷热水相互“混水”现象的作用。
Through the simulation of FLUENT and experiment, the article discloses the principle of the temperature filed and the flow field in all-glass evacuated solar collector tube in the collecting state. It analyzes the factors influencing on the temperature field and the flow field. The article also analyzes the function of inserted rod to the collecting efficiency of evacuated tube installed vertically. In the end of the article, the effect of inserted rod on collecting efficiency is primarily verified by experiment. The following is the major content and study results:
1. According to the solar radiation in long period, the long period direct radiation and scattered radiation per hour on horizontal and vertical plane are computed on the characteristic day of June and December in Shanghai region. This result is fitted into the function of time. For the solar radiation received by evacuated tube installed vertically, based on the Clear Day Solar Radiation Model, the solar radiation distribution on the surface of evacuated tube is calculated by MatLab programming under the different altitude angle and azimuth angle. This result also is fitted into the function of round angle.
2. Through UDF programming, the solar radiation distribution on evacuate tube is acted as the boundary profile in FLUENT. The flow field and the temperature field in evacuated tube are computed in FLUENT. The heat loss and the average temperature of hot water can also be gotten. According to the simulation result, the effect of natural convective heat transfer is good, but there is stagnant zone at the top of evacuated tube. This stagnant zone decreases the collecting performance of evacuated tube.
3. According to the analysis of the factors influencing on the performance of evacuated tube, the absorption co-efficiency and the emission co-efficiency has an important impact on the performance of evacuated tube. The method of inserted rod is proposed to optimize the performance of evacuated tube installed vertically through the simulation of FLUENT. Furthermore, the experiment primarily verifies the function of this method to the performance of evacuated tube.
1．根据长期太阳辐射量计算上海地区在6月和12月代表日(6月11日和12月11日)长期平均小时水平面和垂直面上的太阳直射和散射辐射量，并拟合成时间的函数表达式。对于垂直安装的太阳能集热管所接受的太阳辐射，根据晴天太阳辐射模型，利用MatLab编程计算在不同太阳高度角和方位角的情况下，集热管圆周表面的能流分布，并将其拟合成圆周角的函数表达式。
2．通过UDF文件编程，以集热管表面能流分布作为模拟计算的边界条件，使用FLUENT对集热管内的温度场和流场进行了模拟计算。模拟计算的结果表明，在集热管的顶部和中部自然对流换热效果较为明显，但是在集热管的底部则存在着明显的滞流区，降低了整个集热管的集热性能。
3．通过对集热管集热性能的影响因素的分析可知，选择性涂层的吸收率和发射率对集热管的集热性能有较为明显的影响。如何提高选择性涂层的吸收率，降低选择性涂层的发射率，是提高集热管集热性能的关键。此外，通过模拟和实验验证了内插排挤管的方法对抑制集热管内冷热水相互“混水”现象的作用。
Through the simulation of FLUENT and experiment, the article discloses the principle of the temperature filed and the flow field in all-glass evacuated solar collector tube in the collecting state. It analyzes the factors influencing on the temperature field and the flow field. The article also analyzes the function of inserted rod to the collecting efficiency of evacuated tube installed vertically. In the end of the article, the effect of inserted rod on collecting efficiency is primarily verified by experiment. The following is the major content and study results:
1. According to the solar radiation in long period, the long period direct radiation and scattered radiation per hour on horizontal and vertical plane are computed on the characteristic day of June and December in Shanghai region. This result is fitted into the function of time. For the solar radiation received by evacuated tube installed vertically, based on the Clear Day Solar Radiation Model, the solar radiation distribution on the surface of evacuated tube is calculated by MatLab programming under the different altitude angle and azimuth angle. This result also is fitted into the function of round angle.
2. Through UDF programming, the solar radiation distribution on evacuate tube is acted as the boundary profile in FLUENT. The flow field and the temperature field in evacuated tube are computed in FLUENT. The heat loss and the average temperature of hot water can also be gotten. According to the simulation result, the effect of natural convective heat transfer is good, but there is stagnant zone at the top of evacuated tube. This stagnant zone decreases the collecting performance of evacuated tube.
3. According to the analysis of the factors influencing on the performance of evacuated tube, the absorption co-efficiency and the emission co-efficiency has an important impact on the performance of evacuated tube. The method of inserted rod is proposed to optimize the performance of evacuated tube installed vertically through the simulation of FLUENT. Furthermore, the experiment primarily verifies the function of this method to the performance of evacuated tube.
引文
[1] 中国建筑业协会建筑节能专业委员会北京市建筑节能与墙体材料革新办公室编著．建筑节能：怎么办．北京：中国计划出版社，2002．1
[2] 王庆生．太阳能热水器及其在住宅建设中应用的探讨．安徽建筑，2002年第3期
[3] 曹丽荣．浅论太阳能热水器和住宅一体化．当代建设，2003年第4期
[4] 曹军．太阳能热水器与建筑一体化．农村能源，2002年第2期
[5] 殷志强．全玻璃太阳能真空集热管．科学技术出版社，1998年
[6] Yin Zhiqiang, G.L.Harding, Water-in-glass Manifolds for Heat Extraction from Evacuated Solar Collector Tubes, Solar Energy, Vol.32:223-230, 1984.
[7] G.L.Harding, Yin Zhiqiang, Thermosiphon Circulation in Solar Water Heaters Incorporating Evacuated Tubular Collectors and a Novel Water-in-glass Manifold, Solar Energy, Vol.34:13-18, 1985.
[8] G.L.Harding.Yin Zhiqiang, D.W.Mackey.Heat Extraction Efficiency of a Concentric Glass Tubular Evacuated Collector, Solar Energy, Vol.35:71-79, 1985.
[9] S.C.Mullick, S.K.Nanda, A Improved Technique for Computing the Heat Loss Factor of a TUBULAR Absorber, Solar Energy, Vol.42:3-7, 1989.
[10] N.C.Bhowrnik, S.C.Mullick, Calculation of Tubular Absorber Heating Loss Factor, Solar energy, Vol.35:219-225, 1985.
[11] M.Behnia, G.L.Morrison, An Experimental Investigation of Inclined Open Thermosysphons, Solar Energy, Vol.47:313-326, 1991.
[12] 雷进波．全玻璃太阳能真空集热管流场和温度场的研究．浙江大学硕士学位论文，2004年2月
[13] 王志峰，杨军．带有平面反射板的全玻璃真空集热管表面能流分析．太阳能学报，2005年第4期
[14] 李业发．带排挤管的真空管太阳能热水器实验研究．节能，2002年第8期
[15] 葛洪川，杨军峰．带有内插棒的全玻璃真空管太阳热水器的实验研究．太阳能学报，1996年第7期
[16] S.P.CHOW, G.L.HARDING, K.J.Cathro.Optical efficiency of evacuated tubular collectors with selective surface of high solar absorptance and envelopes coated with antireflection layers.Solar Energy, 1986, Vol.36:241-244.
[17] S.P.Chow, G.L.Harding, Yin Zhiqiang.Optimization of evacuated tubular solar collector arrays with diffuse reflectors.Solar Energy, 1984, Vol.33:277-282.
[18] 王立廷，陆维德，霍志臣等．全玻璃真空集热管内自然对流换热与流动的可视化实验研究．太阳能学报，Vol．8．No．3：305-309，1987．
[19] 陈景仁．液体力学及传热学．国际工业出版社，1983．
[20] 张鹤飞．太阳能热利用原理与计算机模拟．西北工业大学出版社，1990．
[21] 方荣生，项立成等．太阳能应用技术．中国农业机械出版社，1985．
[22] 岑幻霞．太阳能热利用．清华大学出版社，1997．
[23] 郭宽良．数值计算传热学．安徽科学技术出版社，1987
[24] 陈景仁．液体力学及传热学．国际工业出版社，1983
[25] FLUENT6.0 DOCUMENTATION, FLUENT INC.2001.
[26] G.L.Harding.Yin Zhiqiang, D.W.Mackey.HEAT EXTRACTION EFFICIENCY OF A CONCENTRIC GLASS TUBULAR EVACUATED COLLECTOR, solar energy, Vol.3 5:71-79, 1985.
[27] S.C.Mullick, S.K.Nanda, A IMPROVED COMPUTING ABSORBER, THE HEAT LOSS FACTOR TECHNIQUE FOR OF A TUBULAR, solar energy, Vol.4 2:3-7,1989.
[28] 殷志强、吴家庆、陶祖岩等．玻璃真空管集热器的研制．太阳能学报，1981年第4期．
[29] 章熙民、任泽霈、梅飞鸣．传热学．中国建筑工业出版社，1993年．
[30] 郭廷玮，刘鉴民．太阳能的利用．科学技术文献出版社，1987年．
[31] 葛洪川．带有内插棒的全玻璃真空太阳能集热管．中国专利，93202169．7，1993-10-6
[32] 吴家庆、陶祖岩、王风春等．玻璃真空集热管的真空获得与真空寿命，清华大学学报，1982．Vol．22：89-97．
[33] T.Beikircher, G.Goldemund.Gas Heat Conduction in an Evacuated Tube Solar Collector, section physik der Ludwig-Maximilians-Universtadt munchen, amalienstr.54, D-80799 Munchen, Germany.
[2] 王庆生．太阳能热水器及其在住宅建设中应用的探讨．安徽建筑，2002年第3期
[3] 曹丽荣．浅论太阳能热水器和住宅一体化．当代建设，2003年第4期
[4] 曹军．太阳能热水器与建筑一体化．农村能源，2002年第2期
[5] 殷志强．全玻璃太阳能真空集热管．科学技术出版社，1998年
[6] Yin Zhiqiang, G.L.Harding, Water-in-glass Manifolds for Heat Extraction from Evacuated Solar Collector Tubes, Solar Energy, Vol.32:223-230, 1984.
[7] G.L.Harding, Yin Zhiqiang, Thermosiphon Circulation in Solar Water Heaters Incorporating Evacuated Tubular Collectors and a Novel Water-in-glass Manifold, Solar Energy, Vol.34:13-18, 1985.
[8] G.L.Harding.Yin Zhiqiang, D.W.Mackey.Heat Extraction Efficiency of a Concentric Glass Tubular Evacuated Collector, Solar Energy, Vol.35:71-79, 1985.
[9] S.C.Mullick, S.K.Nanda, A Improved Technique for Computing the Heat Loss Factor of a TUBULAR Absorber, Solar Energy, Vol.42:3-7, 1989.
[10] N.C.Bhowrnik, S.C.Mullick, Calculation of Tubular Absorber Heating Loss Factor, Solar energy, Vol.35:219-225, 1985.
[11] M.Behnia, G.L.Morrison, An Experimental Investigation of Inclined Open Thermosysphons, Solar Energy, Vol.47:313-326, 1991.
[12] 雷进波．全玻璃太阳能真空集热管流场和温度场的研究．浙江大学硕士学位论文，2004年2月
[13] 王志峰，杨军．带有平面反射板的全玻璃真空集热管表面能流分析．太阳能学报，2005年第4期
[14] 李业发．带排挤管的真空管太阳能热水器实验研究．节能，2002年第8期
[15] 葛洪川，杨军峰．带有内插棒的全玻璃真空管太阳热水器的实验研究．太阳能学报，1996年第7期
[16] S.P.CHOW, G.L.HARDING, K.J.Cathro.Optical efficiency of evacuated tubular collectors with selective surface of high solar absorptance and envelopes coated with antireflection layers.Solar Energy, 1986, Vol.36:241-244.
[17] S.P.Chow, G.L.Harding, Yin Zhiqiang.Optimization of evacuated tubular solar collector arrays with diffuse reflectors.Solar Energy, 1984, Vol.33:277-282.
[18] 王立廷，陆维德，霍志臣等．全玻璃真空集热管内自然对流换热与流动的可视化实验研究．太阳能学报，Vol．8．No．3：305-309，1987．
[19] 陈景仁．液体力学及传热学．国际工业出版社，1983．
[20] 张鹤飞．太阳能热利用原理与计算机模拟．西北工业大学出版社，1990．
[21] 方荣生，项立成等．太阳能应用技术．中国农业机械出版社，1985．
[22] 岑幻霞．太阳能热利用．清华大学出版社，1997．
[23] 郭宽良．数值计算传热学．安徽科学技术出版社，1987
[24] 陈景仁．液体力学及传热学．国际工业出版社，1983
[25] FLUENT6.0 DOCUMENTATION, FLUENT INC.2001.
[26] G.L.Harding.Yin Zhiqiang, D.W.Mackey.HEAT EXTRACTION EFFICIENCY OF A CONCENTRIC GLASS TUBULAR EVACUATED COLLECTOR, solar energy, Vol.3 5:71-79, 1985.
[27] S.C.Mullick, S.K.Nanda, A IMPROVED COMPUTING ABSORBER, THE HEAT LOSS FACTOR TECHNIQUE FOR OF A TUBULAR, solar energy, Vol.4 2:3-7,1989.
[28] 殷志强、吴家庆、陶祖岩等．玻璃真空管集热器的研制．太阳能学报，1981年第4期．
[29] 章熙民、任泽霈、梅飞鸣．传热学．中国建筑工业出版社，1993年．
[30] 郭廷玮，刘鉴民．太阳能的利用．科学技术文献出版社，1987年．
[31] 葛洪川．带有内插棒的全玻璃真空太阳能集热管．中国专利，93202169．7，1993-10-6
[32] 吴家庆、陶祖岩、王风春等．玻璃真空集热管的真空获得与真空寿命，清华大学学报，1982．Vol．22：89-97．
[33] T.Beikircher, G.Goldemund.Gas Heat Conduction in an Evacuated Tube Solar Collector, section physik der Ludwig-Maximilians-Universtadt munchen, amalienstr.54, D-80799 Munchen, Germany.