热泵型低温蒸发器的实验研究与热力学分析
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摘要
本文针对有热敏性物料的蒸发浓缩和有机溶剂回收问题,建立了一套间歇操作的热泵低温蒸发实验系统。以水为料液,R22为工质进行实验,考察了系统的制热性能系数COP、制热量、蒸发量、蒸发温度、制冷量及热媒流量以及压缩机实际输入功率之间的关系。实验结果表明,系统热负荷、物料蒸发量和冷凝量、系统制热系数COP、压缩机理论耗功量和理论热媒流量均随着料液蒸发温度的升高而增大。蒸发温度在40℃以下,COP在2.8-5.4之间,压缩机的等熵效率在0.53-0.61之间。冷凝器传热阻力随蒸发温度的增大而减小,蒸发器传热阻力在34-35℃存在最小值。蒸发量为4-8.1kg/h二次蒸汽回收率在71%-91%之间,效果较好,能够完成热敏性物料在低温下蒸发的要求。以葡萄糖水溶液为料液的实验结果表明随着压缩机频率的增大,压缩机输入功率、系统制热量和制冷量、料液蒸发量和冷凝量、压缩机有效功率、压缩机效率也呈现相同的增大趋势。蒸发量在4.5-9kg/h,冷凝量为3.4-8kg/h,回收效果较好。同时压缩机效率为70%-90%,系统COPR在3.2-4.9,节能性能较好。
为了进一步研究热泵低温蒸发器的系统性能,本文为以R134a为工质,对系统进行热力学分析,研究了蒸发温度在20-40℃范围内、传热温差分别为5℃、7℃、10℃时系统的热力学性质。计算发现系统COP、制热量、料液蒸发量和工质流量随料液蒸发温度的升高而增大,随传热温差的增大而减小,压缩机功耗增大。在相同蒸发温度下,随着吸气过热度的增大,系统COPH在所选范围内变化不明显,而料液蒸发量缓慢增大,工质流量减小。对于R134a,过热度增大对系统有利。当料液蒸发温度相同时,冷凝器出口过冷度越高,系统COPH越高,料液蒸发量增大,工质流量不变。
The evaporation of heat-sensitive materials is a severe problem in operations. To solve the question, an experiment of low-temperature heat pump evaporator was conducted in this paper. Water and R22were used as material fluid and working medium respectively to study the relationships between the system coefficient of performance COP, heating capacity, evaporation capacity, evaporation temperature, cooling capacity, working medium flow rate and actual compressor input power. The results showed that, when the evaporation temperature increase, the heat load, the material evaporation and condensation capacity, the system heating coefficient of performance COP, compressor theoretical power consumption and the theoretical heating medium flow rate all increased. The evaporation temperature was under40℃, and the COPR was from2.8to5.4, the compressor isentropic efficiency was between0.53-0.61, condenser heat transfer resistance decreased by increasing evaporation temperature, the minimum evaporator heat transfer resistance was at the34-35℃. The system can achieve an evaporation of4-8.1kg/h and the steam recovery was71%-91%, which can efficiently deal with heat-sensitive materials at low temperature evaporation. With glucose solution as the material fluid, the experimental results show that with the increase of compressor frequency and input power, system heating and cooling capacities, evaporation and condensation capacities, compressor effective input power and efficiency all have the same trend of increase. And can achieve an evaporation of4.5-9kg/h and condensation of3.4-8kg/h. With fine energy-saving performance, the efficiency of the compressor is70%-90%, COPR was3.2-4.9.
In order to further study on the system performance of the low-temperature heat pump evaporator, R134a was used as the working fluid to analysis the system thermodynamic characteristics. System thermodynamic properties was studied in the condition of20-40℃ranged evaporation temperature with3specific temperature differences,5℃,7℃,10℃. It was found that the system COP, heating capacity, evaporation capacity and the working fluid flow rate increases along with the evaporation temperature, but decreases when the temperature difference increases, however, the compressor power consumption increases. With the increase of suction superheat at the same evaporation temperature, the system COPH did not change significantly within the selected range, while the evaporation capacity slowly increases and the working fluid flow rate decreases. For R134a, the increases of superheat benefit the system. And when the evaporation temperature is fixed, higher the degree of subcooling can achieve higher system COPH and higher evaporation capacity while working fluid flow rate remains unchanged.
为了进一步研究热泵低温蒸发器的系统性能,本文为以R134a为工质,对系统进行热力学分析,研究了蒸发温度在20-40℃范围内、传热温差分别为5℃、7℃、10℃时系统的热力学性质。计算发现系统COP、制热量、料液蒸发量和工质流量随料液蒸发温度的升高而增大,随传热温差的增大而减小,压缩机功耗增大。在相同蒸发温度下,随着吸气过热度的增大,系统COPH在所选范围内变化不明显,而料液蒸发量缓慢增大,工质流量减小。对于R134a,过热度增大对系统有利。当料液蒸发温度相同时,冷凝器出口过冷度越高,系统COPH越高,料液蒸发量增大,工质流量不变。
The evaporation of heat-sensitive materials is a severe problem in operations. To solve the question, an experiment of low-temperature heat pump evaporator was conducted in this paper. Water and R22were used as material fluid and working medium respectively to study the relationships between the system coefficient of performance COP, heating capacity, evaporation capacity, evaporation temperature, cooling capacity, working medium flow rate and actual compressor input power. The results showed that, when the evaporation temperature increase, the heat load, the material evaporation and condensation capacity, the system heating coefficient of performance COP, compressor theoretical power consumption and the theoretical heating medium flow rate all increased. The evaporation temperature was under40℃, and the COPR was from2.8to5.4, the compressor isentropic efficiency was between0.53-0.61, condenser heat transfer resistance decreased by increasing evaporation temperature, the minimum evaporator heat transfer resistance was at the34-35℃. The system can achieve an evaporation of4-8.1kg/h and the steam recovery was71%-91%, which can efficiently deal with heat-sensitive materials at low temperature evaporation. With glucose solution as the material fluid, the experimental results show that with the increase of compressor frequency and input power, system heating and cooling capacities, evaporation and condensation capacities, compressor effective input power and efficiency all have the same trend of increase. And can achieve an evaporation of4.5-9kg/h and condensation of3.4-8kg/h. With fine energy-saving performance, the efficiency of the compressor is70%-90%, COPR was3.2-4.9.
In order to further study on the system performance of the low-temperature heat pump evaporator, R134a was used as the working fluid to analysis the system thermodynamic characteristics. System thermodynamic properties was studied in the condition of20-40℃ranged evaporation temperature with3specific temperature differences,5℃,7℃,10℃. It was found that the system COP, heating capacity, evaporation capacity and the working fluid flow rate increases along with the evaporation temperature, but decreases when the temperature difference increases, however, the compressor power consumption increases. With the increase of suction superheat at the same evaporation temperature, the system COPH did not change significantly within the selected range, while the evaporation capacity slowly increases and the working fluid flow rate decreases. For R134a, the increases of superheat benefit the system. And when the evaporation temperature is fixed, higher the degree of subcooling can achieve higher system COPH and higher evaporation capacity while working fluid flow rate remains unchanged.
引文
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[43]CHA W S,KIM K B,CHOI K G,et al. Optimum Working Fluid Selection for Automotive Cogeneration System[J]. Engineering and Technology,2010,72.
[44]陈东,谢继红.热泵技术及其应用.北京：化学工业出版社,2006.
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[2]蒋安元.热泵蒸发和热泵蒸煮在板蓝根生产中的应用[J].化学世界.2001,(09)：501-502.
[3]希普R D.热泵[M].第1版,北京：化学工业出版社,1984.
[4]BURSTALL, AUBREY F. A History of Mechanical Engineering[M]. New York:Pitman Publishing Corp.,1963.
[5]RAJPUT R K. Engineering Thermodynamics[M], Sudbury, Mass.:Jones and Bartlett Publishers,2010.
[6]O'NEILL P S, WISZ M W, RAGI E G, et al. Vapour recompression systems with high efficiency components[J]. Chemical Engineering Progress,1985,81(7),57-62.
[7]余永彬.热泵式低温蒸发技术进展[J].上海化工,1987,(05)：18-23.
[8]BRUINSMA D, SPOELSTRA S. Heat pumps in distillation[C]. The Distillation & Absorption Conference, Eindhoven, The Netherlands,12-15 September,2010.
[9]AL-SHAMMIRI M, SAFAR M. Multi-effect distillation plants:state of the art[J]. Desalination,1999,126:45-59.
[10]CHEN Y H, LI Y W, CHANG H. Optimal design and control of solar driven air gap membrane distillation desalination systems[J]. Applied Energy, available online 29 March 2012.
[11]DRISS Z,AHMED 0, ROBERTO S, et al.An optimization model for a mechanical vapor compression desalination plant driven by a wind/PV hybrid system[J]. Applied Energy,2011,88(11):4042-4054.
[12]BILLET R. Evaporation Technology:Principles, Applications, Economics[M]. New York:Wiley, John & Sons, Incorporated,1989.
[13]STANDIFORD F C, BJORK H F, BADGER W L. Evaporation of seawater in long-tube vertical evaporators. Saline Water Conversion, Advances in Chemistry Series, No.27, American Chemical Society, Washington DC,1960,115-127.
[14]SINEK J R. Heat transfer In falling film LTV evaporators[D]. Ann Arbor, Michigan, University of Michigan,1961.
[15]STANDIFORD J R, FERRIS C. Falling-film evaporator:US 3303106[P],1967,02,07.
[16]CHEN H, JEBSON R S. Factors Affecting Heat Transfer in Falling Film Evaporators [J]. Food and Bioproducts Processing,1997,75(2):111-116.
[17]ADIB T A,HEYD B, VASSEUR J. Experimental results and modeling of boiling heat transfer coefficients in falling film evaporator usable for evaporator design[J]. Chemical Engineering and Processing:Process Intensification,2009,48(4):961-968.
[18]KEVILLE J K. Heat transfer aspects of concentrated milk in a falling film evaporator[M]. Syracuse, Syracuse University,1957.
[19]李学斌.影响降膜蒸发器中成膜原因分析[J].氯碱工业,2001,(6)：18-19.
[20]赵元军.降膜蒸发器布膜器的设计[J].化工设备设计,1999,(2)：11-13.
[21]朱玉峰.竖管降膜蒸发器多层喷淋盘式分布器的流量计算[J].河北科技大学学报,2004,25(1)：73-76.
[22]赵斌,张及瑞,赵景利.降膜蒸发器筛板式液体分布装置的实验研究[J].海湖盐与化工,2005,34(4)：12-14.
[23]SALVAGNINI W M, TAQUEDA M S. A Falling-Film Evaporator with Film Promoters[J], Ind. Eng. Chem. Res.2004,43,6832-6835.
[24]吴荣华,岳利茜,李琪.直接式与间接式污水源热泵系统的比较[J].暖通空调,2011,41(9)：111-114.
[25]高寿清.热泵式低温蒸发装置[J].食品与发酵工业,1987,(02)：84-91.
[26]周文生.基于热泵原理的低温蒸发器设计研究[D].南京：南京航空航天大学,2010.
[27]SLESARENKO V V. Heat pumps as a source of heat energy for desalination of seawater [J]. Desalination,2001,139(1-3):405-410.
[28]谢继红,周红,陈东.新型常压低温热泵蒸发浓缩装置[J].轻工机械,2008,(01)：25-28.
[29]陈复彬.蒸发罐的电磁防垢器[J],甘蔗糖业,1980,(5)：42.
[30]赵斌,张及瑞,赵景利.降膜蒸发器筛板式液体分布装置的实验研究[J].海湖盐与化工,2005,34(4)：12-14.
[31]王化淳.热敏性及易结垢性物料加热技术新进展[J].化工进展,1997,(6)：33-35.
[32]尹铭,陈嘉宾,陈沛,马学虎,等.竖直管外降膜吸收传热传质过程强化的研究[J],高校化学工程学报,2002,16(6)：602-608.
[33]郭斌,李会维,韩笃鹏.水平管外降膜流动液膜厚度的测量及分析[J].工程热物理学报,2011,32(1)：71-74.
[34]邓小卫.中药制药浓缩系统热经济性分析及优化[D].重庆：重庆大学,2005.
[35]余永彬.热泵式低温蒸发技术进展[J].上海化工,1987,(05)：18-23.
[36]KUIJPERS L, PEIXOTO R A, CALM J M, ET AL. Current status and trends in HCFC replacement in refrigeration and air refrigeration and air conditioning equipment [J]. IEA Heat pump centre newsletter,2011,29(4):21-23.
[37]CHEN Y. Novel Cycles Using Carbon Dioxide as Working fluid:New Ways to Utilize Energy from Low-Grade Heat Sources[D]. Stockholm,Sweden:Royal Institute of Technology,2006.
[38]张英凡.CO2工质地热泵低温发电装置,中国200820149742[P],2008,10,16.
[39]陈东,谢继红,乔木,许树学.利用工质特性提高热泵制热温度的研究[J].流体机械,2006,34(4)：82-85.
[40]郭涛.中高温热泵工质理论与实验循环性能研究[D].天津：天津大学,2008.
[41]SALEH B, KOGLBAUER G, WENDLAND M, et al. Working fluids for low-temperature organic Rankine cycles[J]. Energy,2007,32:1210-1221.
[42]CHEN H J, GOSWAMI D Y, Stef anakos E K. A review of thermodynamic cycles and working fluids for the conversion of low-grade heat[J]. Renewable and Sustainable Energy Reviews,2010,14:3059-3067.
[43]CHA W S,KIM K B,CHOI K G,et al. Optimum Working Fluid Selection for Automotive Cogeneration System[J]. Engineering and Technology,2010,72.
[44]陈东,谢继红.热泵技术及其应用.北京：化学工业出版社,2006.
[45]United Nations Environment Programme, waste heat recovery, in Energy Efficiency Guide for Industry in Asia[M]. Sweden:United Nations Environment Programme,2006.
[46]BOUMA J. Heat Pumps-Better by Nature:Report on the 7th IEA Heat Pump Conference[J].IEA Heat pump centre newsletter,2002,20(02):10-27.
[47]BP Group. BP世界能源统计年鉴2011. www.bp.com/statisticalreview,2011.06.
[48]夏露,方诩,龚铸.热泵技术在轻工业行业蒸发中的应用[J].广西轻工业,1997,4：7-10.
[49]IRVINE T F, LILEY P E. Steam and Gas Tables with Computer Equations[M]. New York:Academic Press,1984.
[50]WATABE M. Theoretical Study of Condensation of a Multiconponent Vapor Mixture of a Flat Plate(in Japanese)[D].Fukuoka:Kyushu University,1989.
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