回路型重力热管太阳能蒸汽发生系统的设计及理论分析
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摘要
中高温蒸汽在工业上的用途非常广泛，针对工业上需求量很大的180℃左右的蒸汽，本文设计了回路型重力热管太阳能蒸汽发生系统。该系统独创性地把回路型重力热管与抛物槽聚焦集热器结合起来，利用传热性能优良的回路型重力热管把抛物槽聚焦集热器收集到的太阳能传递给锅筒内的水，产生中高温蒸汽。分析表明回路型重力热管适合与抛物槽集热器结合产生中高温蒸汽，在太阳能热利用的中高温领域有着广阔的前景。
本文具体介绍了回路型重力热管太阳能蒸汽发生系统各个部件的设计，对锅筒的设计考虑了其密封、安全阀和压力控制等问题，采用自力式压力调节阀能够使锅筒内蒸汽的压力波动小于±7％，保证了锅筒的稳定安全运行；在完成搭建回路型重力热管太阳能蒸汽发生系统装置的基础上，建立了回路型重力热管系统性能的测量系统，通过分析得到：系统的效率和集热器的效率可以根据测量锅筒的饱和蒸汽温度和压力、回路型重力热管沿程管壁温度、太阳辐射强度以及锅筒排出的蒸汽流量等参数进行计算，并分析确定了上述主要参数的测量方法。
通过对回路型重力热管太阳能蒸汽发生系统的传热过程进行热阻分析，建立了系统性能的计算模型，计算结果表明：集热器的热损失系数U，基本不受太阳辐射强度Ⅰ影响，而受吸收涂层的发射率ε的影响比较大，吸收涂层的发射率ε越高集热器的热损失系数U，越大，采用ε=0.1的化学涂铜黑时和ε=0.9的黑板漆作为吸收涂层时，集热器的热损失系数增大了约6.43W／(m~2·K)；集热器效率η_c和系统效率η随太阳辐射强度Ⅰ的增大而增大，随发射率增大而减少；集热器效率和系统效率随锅筒内饱和蒸汽温度的升高而减少，当锅筒内饱和蒸汽的温度从170℃升高到200℃时，采用ε=0.9黑板漆、ε=0.4选择性吸收涂料和ε=0.1化学涂铜黑作为吸收涂层时，集热器效率分别减少了1.9％、1.1％和0.3％，系统效率分别减少了3.6％、2.8％和2％。
Medium-high temperature steam is widely used in industry, in order to produce about 180°C steam which is needed a lot in industry, a loop thermosyphon solar steam generation system is desighed. This system originally combines the loop thermosyphon with the parabolic trough collector. In this system, loop thermosyphon possessed execellent heat transfer property transfer the solar energy which is collected by the parabolic trough collector to the water in heat exchanger to generate medium-high temperature steam. Some analysis indicate that the technology using loop thermosyphon and the parabolic trough collector to produce medium-high temperature steam is very promising.
In this paper, the design of every part of loop thermosyphon solar steam generation system is introduced,.The seal、safety valve and pressure control and other problems are considered.A pressure auto control is used to make pressure fluctuate less than±7%; on the base of loop thermosyphon solar steam generation system, system efficiency and collector efficiency can be computed by measuring the temperatures and pressures of steam in heat exchanger, temperatures on some point of loop thermosyphon, and steam flow rate of exchanger. The measure method of these parameters are introduced.
Performance compute model is established by analysing heat transfer process and heat resistance of loop thermosyphon system, and the results indicate that: Heatloss coefficient U_L has no business with solar radiate intensity I, but is quite influenced by emissivityεof absorb coat. Heat loss coefficient U_L increases asemissivityεincreases; Heat loss coefficient U_L increase by 6.43 W/(m~2·K) when using chemical copper black(ε= 0.1 ) compares with using blackbloard lacquer(ε= 0.9); Collector efficiencyη_c and system efficiencyηboth increase with solar radiate intensity I increases, and decreased with emissivityεof absorb coat increases; When using blackboard lacquer(ε= 0.9 ),selectively absorb dope(ε= 0.4 )and chemical copper black(ε= 0.1) as absorb coat, the collectorefficiencyη_c and system efficiencyηboth decrease with the increase of steam temperature in heat exchanger, and collector efficiencyη_c respectively decreases by1.9%, 1.1% and 0.3%, meanwhile system efficiencyηrespectively decreases by 3.6%, 2.8% and 2% as steam temperature increases from 170°C to 200°C.
本文具体介绍了回路型重力热管太阳能蒸汽发生系统各个部件的设计，对锅筒的设计考虑了其密封、安全阀和压力控制等问题，采用自力式压力调节阀能够使锅筒内蒸汽的压力波动小于±7％，保证了锅筒的稳定安全运行；在完成搭建回路型重力热管太阳能蒸汽发生系统装置的基础上，建立了回路型重力热管系统性能的测量系统，通过分析得到：系统的效率和集热器的效率可以根据测量锅筒的饱和蒸汽温度和压力、回路型重力热管沿程管壁温度、太阳辐射强度以及锅筒排出的蒸汽流量等参数进行计算，并分析确定了上述主要参数的测量方法。
通过对回路型重力热管太阳能蒸汽发生系统的传热过程进行热阻分析，建立了系统性能的计算模型，计算结果表明：集热器的热损失系数U，基本不受太阳辐射强度Ⅰ影响，而受吸收涂层的发射率ε的影响比较大，吸收涂层的发射率ε越高集热器的热损失系数U，越大，采用ε=0.1的化学涂铜黑时和ε=0.9的黑板漆作为吸收涂层时，集热器的热损失系数增大了约6.43W／(m~2·K)；集热器效率η_c和系统效率η随太阳辐射强度Ⅰ的增大而增大，随发射率增大而减少；集热器效率和系统效率随锅筒内饱和蒸汽温度的升高而减少，当锅筒内饱和蒸汽的温度从170℃升高到200℃时，采用ε=0.9黑板漆、ε=0.4选择性吸收涂料和ε=0.1化学涂铜黑作为吸收涂层时，集热器效率分别减少了1.9％、1.1％和0.3％，系统效率分别减少了3.6％、2.8％和2％。
Medium-high temperature steam is widely used in industry, in order to produce about 180°C steam which is needed a lot in industry, a loop thermosyphon solar steam generation system is desighed. This system originally combines the loop thermosyphon with the parabolic trough collector. In this system, loop thermosyphon possessed execellent heat transfer property transfer the solar energy which is collected by the parabolic trough collector to the water in heat exchanger to generate medium-high temperature steam. Some analysis indicate that the technology using loop thermosyphon and the parabolic trough collector to produce medium-high temperature steam is very promising.
In this paper, the design of every part of loop thermosyphon solar steam generation system is introduced,.The seal、safety valve and pressure control and other problems are considered.A pressure auto control is used to make pressure fluctuate less than±7%; on the base of loop thermosyphon solar steam generation system, system efficiency and collector efficiency can be computed by measuring the temperatures and pressures of steam in heat exchanger, temperatures on some point of loop thermosyphon, and steam flow rate of exchanger. The measure method of these parameters are introduced.
Performance compute model is established by analysing heat transfer process and heat resistance of loop thermosyphon system, and the results indicate that: Heatloss coefficient U_L has no business with solar radiate intensity I, but is quite influenced by emissivityεof absorb coat. Heat loss coefficient U_L increases asemissivityεincreases; Heat loss coefficient U_L increase by 6.43 W/(m~2·K) when using chemical copper black(ε= 0.1 ) compares with using blackbloard lacquer(ε= 0.9); Collector efficiencyη_c and system efficiencyηboth increase with solar radiate intensity I increases, and decreased with emissivityεof absorb coat increases; When using blackboard lacquer(ε= 0.9 ),selectively absorb dope(ε= 0.4 )and chemical copper black(ε= 0.1) as absorb coat, the collectorefficiencyη_c and system efficiencyηboth decrease with the increase of steam temperature in heat exchanger, and collector efficiencyη_c respectively decreases by1.9%, 1.1% and 0.3%, meanwhile system efficiencyηrespectively decreases by 3.6%, 2.8% and 2% as steam temperature increases from 170°C to 200°C.
引文
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[3] 赵玉．21世纪我国太阳能利用发展趋势，中国电力，2000，Vol．33：73-77
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[5] 陈维，李歌洪．抛物柱面聚焦的几种跟踪方式的光学性能分析．太阳能学报，2003，24(4)：477-482．
[6] Thomas A. Solar steam generation system using parabolic trough concentrators. Energy Conversion and Management, 1996, 37(2): 215-245.
[7] 刘毓伟，陈滨．抛物槽太阳能集热器发电系统．电力需求侧管理，2004，6(6)：38-46
[8] Rafael Almanza, Alvaro Lentz and Gustavo Jimenez. Receiver behavior in direct steam generation with parabolic troughs. Solar Energy, 1997, 61(4): 275-278.)
[9] Markus Eck, Tobias Hirsch. Dynamics and control of parabolic trough collector loops with direct steam generation. Solar Energy, 2007, 81:268-27
[10] 张耀明，王军，张文进，孙利国，刘晓辉．塔式与槽式太阳能热发电，太阳能，2006，Vol．2：29-32。
[11] 徐培富．国内太阳能热利用简况，能源工程，2002，Vol．1：15-18
[12] 罗智慧，龙新峰．槽式太阳能热发电技术研究现状与发展．电力设备，2006，Vol7(11)：29-32
[13] M. Eck a,, E. Zarza, Saturated steam process with direct steam generating parabolic troughs, Solar Energy 80(2006):1424-1433
[14] M. Ecka, E.Zarzab, M.Eickhoffa, J.Rheinlanderc, L.Valenzuelab. Applied research concerning the direct steam generation in parabolic troughs, Solar Energy 74 (2003): 341-351
[15] Markus Eck., Wolf-Dieter Steinmann, Jurgen Rheinlander. Maximum temperature difference in horizontal and tilted absorber pipes with direct steam generation, Energy 29 (2004):665-676
[16] L.Valenzuela, E.Zarza, M. Berenguel, E.F.Camacho. Control scheme for direct steam generation in parabolic troughs under recirculation operation mode, Solar Energy 80 (2006):1-17
[17] Vicente Flores, Rafael Almanza.Behavior of the compound wall copper-steel receiver with stratified two-phase flow regimen in transient states when solar irradiance is arriving on one side of receiver, Solar Energy 76 (2004):195-198
[18] Vicente Flores, Rafael Almanza.Direct steam generation in parabolic trough concentrators with bimetallic receivers, Energy 29 (2004):645-651
[19] G.C.Bakos, I. Ioannidis, N.F. Tsagas, I. Seftelis.Design,optimisation and conversion-efficiency determination of a line-focus parabolic-trough solar-collector (PTC), Applied Energy 68 (2001) 43-50.
[20] S.D.ODEH, G.L.MORRISON and M.BEHNIA.MODELLING OF PARABOLIC TROUGH DIRECT STEAM,GENERATION SOLAR COLLECTORS, Solar Energy Vol. 62, No. 6, pp. 395-406, 1998
[21] 文玉良，浦绍选，唐润生．热管在太阳能热利用技术中的应用，可再生能源 2005．2：28-30
[22] 孙全平，陈晓华，陈金发．太阳能热管的研制和应用，能源技术，2002，Vol．23：110-112
[23] Rafael Almanza,Alvaro Lentz and Gustavo Jimenez. Receiver behaviro in direct steam generation with parabolic troughs. Solar Energy, 1997, Vol.61 (4):275-278
[24] 赵辉．高热流密度回路型重力热管散热器传热特性的理论研究．杭州：浙江大学硕士学位论文 2004．01
[25] 王雪峰．回路型重力热管散热器沸腾传热的实验研究及数值分析．杭州：浙江大学硕士学位论文，2005．03
[26] 孙志坚，彭耀锋，洪荣华等．回路型重力热管蒸发器的Fluent数值模拟，第十届热管会义论文集，2006：184-192
[27] 方荣生，向立成，李亭寒，陈小霓．太阳能应用技术．北京：中国农业机械出版社，1985
[28] 刘自强，邢丙丙，庄向东．重力热管在真空管式热水器中的应用，新能源 2000，22(6)：45-47
[29] 吴存真，刘光铎。热管在热能工程中的应用．北京：水利水电出版社，1993
[30] 尾花英朗，徐忠权．热交换器设计手册．北京：石油工业出版社，1981
[31] 杨世铭，陶文铨。传热学(第三版)．北京：高等教育出版社，1998
[32] 伊萨琴科BП．传热学．王丰，冀守礼，周筠清等译．北京：高等教育出版社
[33] 葛子余．金属软管，北京：宇航出版社，1985
[34] 庄骏，徐通明，石寿椿．热管与热管换热器，上海：上海交通大学出版社，1989
[35] 屠传经，洪荣华，王鹏举．重力热管式换热器及其在余热利用中的应用，杭州：浙江大学出版社，1989
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