相变集热蓄热墙供暖性能优化研究——以拉萨地区为例
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摘要
青藏高原地区大力提倡被动式太阳能采暖,集热蓄热墙即其中一项重要技术,但应用中仍存在平均室温低、室温波动较大等问题。本文考虑太阳能选择性吸收涂层、PC中空板、定形相变材料的应用以改善集热蓄热墙的集热效率与供暖稳定性。利用Fluent建立其二维瞬态模型,并考虑高原低空气密度、低自然对流换热系数等特点修正模型输入参数。经验证平均误差在10%以内。模拟结果表明:相变集热蓄热墙集热效率对集热面发射率敏感,使用选择性涂层后由21.9%增大至43.2%;透明盖板采用轻质、不易碎的PC中空板,集热效率与普通玻璃持平;定形相变材料可调节一日内供热量分布以改善供暖稳定性,可降低瞬时供热量日振幅32.5%,相变温度偏低时作用效果明显变差,而相变温区宽窄为非敏感因素。
Passive solar heating is highly recommended in Tibet, of which Trombe wall is an important technique, but there are still problems like the indoor air temperature is still below the thermal comfort zone and fluctuates strongly during one day. Solar selective absorbing coating, polycarbonate(PC) hollow panel and shape-stabilized phase change material(SSPCM) are considered to improve the solar collecting efficiency and heating stability of Trombe wall. A two-dimensional transient numerical model of the phase-change Trombe wall is built using Fluent to simulate its thermal performance. Besides, the small air density and low free convection heat transfer coefficient in plateau are considered to amend the input parameters. Through validation, the average errors are considered within 10%. The results are: Decrease on the long-wave emittance of the solar absorbing coating contributes significantly to the solar collecting efficiency of Trombe wall, which increases from 21.9% to 43.2% after using a solar selective absorbing coating instead of the black-painted surface; An 8 mm PC hollow panel performs equivalent heat collecting efficiency as a 3 mm common glass, but with the characteristics of lighter weight and breakage proof; Application of the SSPCM board can adjust the distribution of daily instant heat supply to realize better heating stability, thus reducing the daily fluctuation of heat supply rate by 32.5%; For thermal design of SSPCM, decrease on the phase change temperature from the optimal value should be avoided, for it may greatly reduce the effect on improving heating stability, while the range of phase transition temperature is not a sensitive factor.
Passive solar heating is highly recommended in Tibet, of which Trombe wall is an important technique, but there are still problems like the indoor air temperature is still below the thermal comfort zone and fluctuates strongly during one day. Solar selective absorbing coating, polycarbonate(PC) hollow panel and shape-stabilized phase change material(SSPCM) are considered to improve the solar collecting efficiency and heating stability of Trombe wall. A two-dimensional transient numerical model of the phase-change Trombe wall is built using Fluent to simulate its thermal performance. Besides, the small air density and low free convection heat transfer coefficient in plateau are considered to amend the input parameters. Through validation, the average errors are considered within 10%. The results are: Decrease on the long-wave emittance of the solar absorbing coating contributes significantly to the solar collecting efficiency of Trombe wall, which increases from 21.9% to 43.2% after using a solar selective absorbing coating instead of the black-painted surface; An 8 mm PC hollow panel performs equivalent heat collecting efficiency as a 3 mm common glass, but with the characteristics of lighter weight and breakage proof; Application of the SSPCM board can adjust the distribution of daily instant heat supply to realize better heating stability, thus reducing the daily fluctuation of heat supply rate by 32.5%; For thermal design of SSPCM, decrease on the phase change temperature from the optimal value should be avoided, for it may greatly reduce the effect on improving heating stability, while the range of phase transition temperature is not a sensitive factor.
引文
[1] 中国建筑设计研究院,山东建筑大学.JGJ/T 267—2012被动式太阳能建筑技术规范[S].北京:中国建筑工业出版社,2012:4,13
[2] 西安建筑科技大学,西藏自治区建筑勘察设计院.DB 54/0016—2007西藏自治区地方标准:居住建筑节能设计标准[S].西藏:西藏人民出版社,2007:5,51
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[6] Saadatian O,Sopian K,Lim CH,et al.Trombe walls:A review of opportunities and challenges in research and development [J].Renewable and Sustainable Energy Reviews,2012,16(8):6340-6351
[7] 王蕊,张万钢,魏海波.浅谈平板太阳能集热器选择性吸收涂层的制备及发展前景[J].科技致富向导,2010,20:86-99
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[9] Zhang Y P,Yang R,Di H F,et al.Preparation,thermal performance and application of shape-stabilized PCM in energy efficient buildings [J].Energy and Building,2006,38(10):1262-1269
[10] Zhang Y P,Di H F,Wang X,et al.Influence of additives on thermal conductivity of shape-stabilized phase change material [J].Solar Energy Materials and Solar Cells,2006,90:1692-1702
[11] 肖伟.藏西南边远地区直接受益式太阳能采暖研究[D].北京:清华大学,2010
[12] 周允华.青藏高原的大气热辐射和天空有效温度[J].太阳能学报,1984,(03):232-241
[13] 北京楚格广源科技有限公司.阳光板技术参数[EB/OL].[2018-08-01].http://www.chggy.com/sv.aspx?TypeId=127&FId=t8:127:8
[14] Diarce G,Campos-Celador A,Martin K,et al.A comparative study of the CFD modeling of a ventilated active fa?ade including phase change materials [J].Applied Energy,2014,126:307-317
[15] ANSYS Inc.Lecture 4-Natural Convection[R].ANSYS Fluent Customer Training Material,2010
[16] Liu S L,Li Y C.An experimental study on the thermal performance of a solar chimney without and with PCM [J].Renewable Energy,2015,81:338-346
[17] Liu S L,Li Y C.Heating performance of a solar chimney combined PCM:A numerical case study [J].Energy and Buildings,2015,99:117-130
[2] 西安建筑科技大学,西藏自治区建筑勘察设计院.DB 54/0016—2007西藏自治区地方标准:居住建筑节能设计标准[S].西藏:西藏人民出版社,2007:5,51
[3] 王斌.集热蓄热墙传热过程及优化设计研究[D].西安:西安建筑科技大学,2012
[4] 刘娟.青藏高原地区被动式太阳房的试验研究[J].太阳能,2011,19:45-48
[5] 王登甲,刘艳峰,刘加平,等.青藏高原地区Trombe墙式太阳房供暖性能测试分析[J].太阳能学报,2013,34(10):1823-1828
[6] Saadatian O,Sopian K,Lim CH,et al.Trombe walls:A review of opportunities and challenges in research and development [J].Renewable and Sustainable Energy Reviews,2012,16(8):6340-6351
[7] 王蕊,张万钢,魏海波.浅谈平板太阳能集热器选择性吸收涂层的制备及发展前景[J].科技致富向导,2010,20:86-99
[8] 崔萌.“阳光板”在当代建筑中的应用研究[D].南京:南京大学,2011
[9] Zhang Y P,Yang R,Di H F,et al.Preparation,thermal performance and application of shape-stabilized PCM in energy efficient buildings [J].Energy and Building,2006,38(10):1262-1269
[10] Zhang Y P,Di H F,Wang X,et al.Influence of additives on thermal conductivity of shape-stabilized phase change material [J].Solar Energy Materials and Solar Cells,2006,90:1692-1702
[11] 肖伟.藏西南边远地区直接受益式太阳能采暖研究[D].北京:清华大学,2010
[12] 周允华.青藏高原的大气热辐射和天空有效温度[J].太阳能学报,1984,(03):232-241
[13] 北京楚格广源科技有限公司.阳光板技术参数[EB/OL].[2018-08-01].http://www.chggy.com/sv.aspx?TypeId=127&FId=t8:127:8
[14] Diarce G,Campos-Celador A,Martin K,et al.A comparative study of the CFD modeling of a ventilated active fa?ade including phase change materials [J].Applied Energy,2014,126:307-317
[15] ANSYS Inc.Lecture 4-Natural Convection[R].ANSYS Fluent Customer Training Material,2010
[16] Liu S L,Li Y C.An experimental study on the thermal performance of a solar chimney without and with PCM [J].Renewable Energy,2015,81:338-346
[17] Liu S L,Li Y C.Heating performance of a solar chimney combined PCM:A numerical case study [J].Energy and Buildings,2015,99:117-130