纵流式换热器流动与传热特性的研究
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摘要
纵流式换热器是一种综合性能较好的新型换热器，在换热量相同时，所消耗的泵功率相对于折流板式换热器较少。由于纵流式换热器的壳程结构不同于折流板式换热器，本文对纵流式换热器的传热和流动阻力性质进行了研究；对其结构变化引起的壳程流场和温度变化做了以下工作：
1.采用数值模拟方法，研究了纵流式换热器和折流板式换热器流场和温度场的分布。以往对换热器壳程流场和温度场的数值模拟都是建立在多孔介质模型基础上进行的，存在许多问题。由于多孔介质模型的不完善性，本文首次采用湍流模型研究了纵流式换热器的工作特性。
2.根据换热器的实际结构，对纵流式换热器和折流板式换热器进行了适当简化，并以此为基础建立了计算模型并进行了数值模拟，得到了纵流式换热器和折流板换热器内的流场和温度场。两者相比，纵流式换热器壳程特有的支撑结构不仅增加了传热表面积，而且在流动中起到增强流体扰动和湍流度的作用；与此同时，流场中的流动滞止区相对减小，流动阻力减小；同时，温度场分布更均匀。
3.采用热力学第一定律和热力学第二定律的基本原理，分析比较了两种换热器的性能。认为只有综合考虑换热器的传热特性和压降特性，才能较为准确、客观地分析换热器的性能。
本文的研究表明：在用数值方法模拟换热器中的流场与温度场时，采用湍流模型可以比用多孔介质模型获得更详细、准确的换热器内部流场与温度场信息；同时，本研究对换热器进行的性能分析也表明纵流式换热器有较好的流动与传热特性。
Longitudinal-flow heat exchanger is a new type of heat exchanger, which consumes less pump power than baffle board heat exchanger at the exchanging same quantity of heat. In this paper, the characters of heat transfer and flow resistance on longitudinal-flow heat exchanger are investigated. The Longitudinal-flow heat exchange is different from the baffle board heat exchanger in shell structure which lead to various flow field and temperature field, therefore the study on it is undertook as following:
1. The distribution of the temperature field and flow field in longitudinal-flow heat exchanger is explored by numerical method. Generally the numerical stimulation on flow field and temperature field of shell distance is based on porous medium model. For the first time, the distribution of flow field and temperature field is stimulated with turbulent current model in this paper.
2. Longitudinal-flow heat exchanger and baffle board heat exchanger are predigested on the base of full-scale entity. Based on the models, flow field and temperature field are calculated with numerical stimulation method. Compared with baffle board heat exchanger, the structure of longitudinal-flow heat exchanger has supporting tube, which not only enhance heat transfer area but also have an effect on remolding and reinforcing turbulence. At the same time, the distribution of flow field and temperature field in longitudinal-flow heat exchanger is more uniform than that in baffle board heat exchanger. Meanwhile, the numerical investigation indicates that the Longitudinal-flow heat exchanger has less flow resistance.
3. The character of longitudinal-flow heat exchanger and baffle board heat exchanger is analyzed with the first law of thermodynamics and the second law of thermodynamics. The result shows the performance of heat exchanger can only be preferably analyzed with the second law of thermodynamics on base of considering characteristic of heat transfer and flow resistance.
In a word, the flow field and temperature field can be simulated in detail by numerical calculation of turbulent current model rather than porous medium model. And longitudinal-flow heat exchange has preferably performance by analysis.
1.采用数值模拟方法，研究了纵流式换热器和折流板式换热器流场和温度场的分布。以往对换热器壳程流场和温度场的数值模拟都是建立在多孔介质模型基础上进行的，存在许多问题。由于多孔介质模型的不完善性，本文首次采用湍流模型研究了纵流式换热器的工作特性。
2.根据换热器的实际结构，对纵流式换热器和折流板式换热器进行了适当简化，并以此为基础建立了计算模型并进行了数值模拟，得到了纵流式换热器和折流板换热器内的流场和温度场。两者相比，纵流式换热器壳程特有的支撑结构不仅增加了传热表面积，而且在流动中起到增强流体扰动和湍流度的作用；与此同时，流场中的流动滞止区相对减小，流动阻力减小；同时，温度场分布更均匀。
3.采用热力学第一定律和热力学第二定律的基本原理，分析比较了两种换热器的性能。认为只有综合考虑换热器的传热特性和压降特性，才能较为准确、客观地分析换热器的性能。
本文的研究表明：在用数值方法模拟换热器中的流场与温度场时，采用湍流模型可以比用多孔介质模型获得更详细、准确的换热器内部流场与温度场信息；同时，本研究对换热器进行的性能分析也表明纵流式换热器有较好的流动与传热特性。
Longitudinal-flow heat exchanger is a new type of heat exchanger, which consumes less pump power than baffle board heat exchanger at the exchanging same quantity of heat. In this paper, the characters of heat transfer and flow resistance on longitudinal-flow heat exchanger are investigated. The Longitudinal-flow heat exchange is different from the baffle board heat exchanger in shell structure which lead to various flow field and temperature field, therefore the study on it is undertook as following:
1. The distribution of the temperature field and flow field in longitudinal-flow heat exchanger is explored by numerical method. Generally the numerical stimulation on flow field and temperature field of shell distance is based on porous medium model. For the first time, the distribution of flow field and temperature field is stimulated with turbulent current model in this paper.
2. Longitudinal-flow heat exchanger and baffle board heat exchanger are predigested on the base of full-scale entity. Based on the models, flow field and temperature field are calculated with numerical stimulation method. Compared with baffle board heat exchanger, the structure of longitudinal-flow heat exchanger has supporting tube, which not only enhance heat transfer area but also have an effect on remolding and reinforcing turbulence. At the same time, the distribution of flow field and temperature field in longitudinal-flow heat exchanger is more uniform than that in baffle board heat exchanger. Meanwhile, the numerical investigation indicates that the Longitudinal-flow heat exchanger has less flow resistance.
3. The character of longitudinal-flow heat exchanger and baffle board heat exchanger is analyzed with the first law of thermodynamics and the second law of thermodynamics. The result shows the performance of heat exchanger can only be preferably analyzed with the second law of thermodynamics on base of considering characteristic of heat transfer and flow resistance.
In a word, the flow field and temperature field can be simulated in detail by numerical calculation of turbulent current model rather than porous medium model. And longitudinal-flow heat exchange has preferably performance by analysis.
引文
(1).余敏。李美玲，蔡祖恢，徐益峰。王建容。板翅式换热器在大型电站气轮发电机冷却系统中的应用研究，动力工程，V0l.18,No.5, pp54,1998
(2).杨世铭， 陶文铨编著《传热学》第三版，高等教育出版社
(3).邓忠 康天源 主编，《化学工程师简明手册》，机械工业出版社
(4).阎皓峰、甘永平编著《新型换热器与传热强化》，宇航出版社1991年
(5).吴金星 董其伍等，《纵流式换热器的结构研究进展》，化工进展2002年21卷第5期
(6).N.H.艾夫根 E.U.施林德尔 主编《换热器设计与理论源典》机械工业出版社P23
(7).孙奉仲，换热器强化传热与可靠性增长的综合研究及其工程应用：【博士学位论文】西安，西安交通大学，2001
(8) 胡延东, 管壳式换热器壳侧流场与温度场的三维数值模拟,：【硕士学位论文】西安，西安交通大学，2001
(9).Grimson E.D.Correlation and utilization of new data on flow resistance and heat transfer for crossflow of gases over tube banks.Trans ASME,1937,59:583-594
(10).如可乌斯卡斯AA.换热器内的对流传热。马昌文，居滋泉，肖宏才译。北京：科学出版社，1986.337—370
(11)Beijin A,Large J L.The Pr number effect on the transition in natural convection along a vertical surface. ASME J heat Transfer,1990,112:787－790
(12) 是勋刚，《湍流》，天津：天津大学出版社,1994，3
(13) 高青,传热管强化传热性能评价方法研究,化工机械,19卷,第五期
(14) 杨世铭,陶文铨编著,传热学(第三版),北京：高等教育出版社，1998.12
(17)钱松文等，《换热器管束流体力学与传热》北京：中国石化出版社，2002.1,P17,19,30,38
(18)Prithiviraj M,Andrews M J.There dimensional numerical simulation of shell-and-tube heat exchangers. Part I: Foundation and Fluid Mechanics. Numerical Heat Transfer,1998,33A:799-816
(19)陶文铨，《数值传热学》（第二版），西安，西安交通大学出版社，2001.1,P497，333,483
(20)(日本)尾花英郎编，《热交换器手册》，加工出版社，1987。
(21)倪振伟等编，《评价换热器热性能的三项指标》，工程热物理学报，P387-389,Vol.5 No.4,1984
(22)熊大曦、李志信、过增元编《换热器的效能与熵产分析》，工程热物理学报，p90-94,Vol.18 Nu.1,1997
(23)高青、卓宁编，《传热管强化传热能质综合分析》，化工学报，P90-95,Vol.44No.1,1993
(24)Chen C-J, Jaw S-Y. Fundamentals of turbulence modeling. Washington
DC:Taylor&Francis,1998.xi:91-92,119,69,71,63,64
(25)Markatos N C, The mathematical modeling of turbulence flows.Applied math modeling,1986,10:190-220
(26).倪振伟等编，《换热器的熵增计算法与总熵增率》，工程热物理学报，P4-6,Vol9 No.1,1988
(27).Orszag S A.Numerical simulation of turbulence flows.In:Frost W,Moulden T H,eds.Handbook of turbulence.New York:Plenum Press,1977.281-313
(28).Launder, B, E, Spalding, D,B, The numerical computation of Turbulent Flows, Computer Methods In Applied Mechanics and Engineering ,1974,Vol3,P269-289
(29).J.E.Hesselgreaves,《Rationalization of second law analysis of heat exchangers》，HEAT and MASS TRANSFER,P4189-4204,Vol.2000 No.43,2000
(2).杨世铭， 陶文铨编著《传热学》第三版，高等教育出版社
(3).邓忠 康天源 主编，《化学工程师简明手册》，机械工业出版社
(4).阎皓峰、甘永平编著《新型换热器与传热强化》，宇航出版社1991年
(5).吴金星 董其伍等，《纵流式换热器的结构研究进展》，化工进展2002年21卷第5期
(6).N.H.艾夫根 E.U.施林德尔 主编《换热器设计与理论源典》机械工业出版社P23
(7).孙奉仲，换热器强化传热与可靠性增长的综合研究及其工程应用：【博士学位论文】西安，西安交通大学，2001
(8) 胡延东, 管壳式换热器壳侧流场与温度场的三维数值模拟,：【硕士学位论文】西安，西安交通大学，2001
(9).Grimson E.D.Correlation and utilization of new data on flow resistance and heat transfer for crossflow of gases over tube banks.Trans ASME,1937,59:583-594
(10).如可乌斯卡斯AA.换热器内的对流传热。马昌文，居滋泉，肖宏才译。北京：科学出版社，1986.337—370
(11)Beijin A,Large J L.The Pr number effect on the transition in natural convection along a vertical surface. ASME J heat Transfer,1990,112:787－790
(12) 是勋刚，《湍流》，天津：天津大学出版社,1994，3
(13) 高青,传热管强化传热性能评价方法研究,化工机械,19卷,第五期
(14) 杨世铭,陶文铨编著,传热学(第三版),北京：高等教育出版社，1998.12
(17)钱松文等，《换热器管束流体力学与传热》北京：中国石化出版社，2002.1,P17,19,30,38
(18)Prithiviraj M,Andrews M J.There dimensional numerical simulation of shell-and-tube heat exchangers. Part I: Foundation and Fluid Mechanics. Numerical Heat Transfer,1998,33A:799-816
(19)陶文铨，《数值传热学》（第二版），西安，西安交通大学出版社，2001.1,P497，333,483
(20)(日本)尾花英郎编，《热交换器手册》，加工出版社，1987。
(21)倪振伟等编，《评价换热器热性能的三项指标》，工程热物理学报，P387-389,Vol.5 No.4,1984
(22)熊大曦、李志信、过增元编《换热器的效能与熵产分析》，工程热物理学报，p90-94,Vol.18 Nu.1,1997
(23)高青、卓宁编，《传热管强化传热能质综合分析》，化工学报，P90-95,Vol.44No.1,1993
(24)Chen C-J, Jaw S-Y. Fundamentals of turbulence modeling. Washington
DC:Taylor&Francis,1998.xi:91-92,119,69,71,63,64
(25)Markatos N C, The mathematical modeling of turbulence flows.Applied math modeling,1986,10:190-220
(26).倪振伟等编，《换热器的熵增计算法与总熵增率》，工程热物理学报，P4-6,Vol9 No.1,1988
(27).Orszag S A.Numerical simulation of turbulence flows.In:Frost W,Moulden T H,eds.Handbook of turbulence.New York:Plenum Press,1977.281-313
(28).Launder, B, E, Spalding, D,B, The numerical computation of Turbulent Flows, Computer Methods In Applied Mechanics and Engineering ,1974,Vol3,P269-289
(29).J.E.Hesselgreaves,《Rationalization of second law analysis of heat exchangers》，HEAT and MASS TRANSFER,P4189-4204,Vol.2000 No.43,2000