LNG绕管式换热器壳侧降膜沸腾数值模拟研究
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摘要
使用ANSYS Fluent商用软件下的VOF模型,对天然气液化工艺中所用的绕管式换热器壳侧降膜沸腾过程进行了数值模拟。结果表明,当壳侧入口干度x≤0.10时,VOF模型能较好地模拟壳侧沸腾换热现象,准确地预测出沸腾换热系数与冷剂质量流率间的关系。降膜流状态下,汽、液相流速较低,摩擦压降较小,换热管壁面基本被液膜覆盖,液相冷剂在受热壁面汽化后进入壳侧流道,流道内以汽相为主。壳侧既有竖直向下的主流运动,又有较为微弱的螺旋环流,同时大量的汽相将在壳侧顶部涡旋滞留。
The volume of fluid(VOF) model which attaches to the ANSYS Fluent software was employed to simulate the shell-side falling film boiling of spiral wound heat exchanger(SWHE). When inlet quality in shell-side is not more than 0.10, the shell-side boiling can be well simulated by the VOF model, and the boiling heat transfer coefficient that is related to refrigerant mass velocity may be accurately predicted. For falling film flow, the vapor velocity and the liquid velocity are so low that friction pressure drop is small. The heated wall is generally covered by the liquid film, the liquid phase will turn into the vapor phase, separate from the heated wall and enter into the flow channel of shell-side after the tube-side heat is absorbed. Besides the refrigerant flowing down which is dominant on the shell-side, the spiral flowing which is minor can be found, and the vapor eddy which stays at the top of shell-side may be identified.
The volume of fluid(VOF) model which attaches to the ANSYS Fluent software was employed to simulate the shell-side falling film boiling of spiral wound heat exchanger(SWHE). When inlet quality in shell-side is not more than 0.10, the shell-side boiling can be well simulated by the VOF model, and the boiling heat transfer coefficient that is related to refrigerant mass velocity may be accurately predicted. For falling film flow, the vapor velocity and the liquid velocity are so low that friction pressure drop is small. The heated wall is generally covered by the liquid film, the liquid phase will turn into the vapor phase, separate from the heated wall and enter into the flow channel of shell-side after the tube-side heat is absorbed. Besides the refrigerant flowing down which is dominant on the shell-side, the spiral flowing which is minor can be found, and the vapor eddy which stays at the top of shell-side may be identified.
引文
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[13] Xin R C,Ebadian M A.The effects of Prandtl numbers on local and average convective heat transfer characteristics in helical pipes[J].Journal of Heat Transfer,1997,119(3):467-473
[14] Yang Z,Peng X,Ye P.Numerical and experimental investigation of two phase flow during boiling in a coiled tube[J].International Journal of Heat and Mass Transfer,2008,51(5):1 003-1 016
[15] Lee W H.A pressure iteration scheme for two-phase flow modeling[J].Multiphase Transport Fundamentals,Reactor Safety,Applications,1980,1:407-431
[16] Wu Z,Cai W,Qiu G,et al.Prediction of mass transfer time relaxation parameter for boiling simulation on the shell-side of LNG spiral wound heat exchanger[C]//Advances in Mechanical Engineering,New York:Hindawi Publishing Corporation,2014
[17] Orszag S A,Yakhot V,Flannery W S,et al.Renormalization group modeling and turbulence simulations[C]//Proceedings of the International Conference on Near-Wall Turbulent Flows.Arizona:Elsevier Science Publishers BV,1993 收录本刊的部分检索系统数据库
[2] 吴志勇,陈杰,浦晖,等.LNG绕管式换热器壳侧过热流动的数值模拟[J].煤气与热力,2014,34(8):B6-B11Wu Zhiyong,Chen Jie,Pu Hui,et al.Numerical simulation of superheated flow of refrigerant at shell side of LNG spiral wound heat exchanger[J].Gas and Heat,2014,34(8):B6-B11(in Chinese)
[3] Steffen H.Near-Optimal operation of LNG liquefaction processes by means of regulation[D].Berlin:Berlin Institute of Technology,2011
[4] Neeraas B O.Condensation of hydrocarbon mixtures in coil-wound LNG heat exchangers tube-side heat transfer and pressure drop [D].Trondheim:Norwegian Institute of Technology,1993
[5] Aunan B.Shell-Side heat transfer and pressure drop in coil-wound LNG heat exchanger[D].Trondheim:Norwegian University of Science and Technology,2000
[6] Moawed M.Experimental study of forced convection from helical coiled tubes with different parameters[J].Energy Conversion and Management,2011,52(2):1 150-1 156
[7] Yang Z,Zhao Z,Liu Y,et al.Convective heat transfer characteristics of high-pressure gas in heat exchanger with membrane helical coils and membrane serpentine tubes[J].Experimental Thermal and Fluid Science,2011,35(7):1 427-1 434
[8] Jamshidi N,Farhadi M,Ganji D D.et al.Experimental analysis of heat transfer enhancement in shell and helical tube heat exchangers[J].Applied Thermal Engineering,2013,51(2):644-652
[9] Shokouhmand H,Salimpour M R,Akhavan M A.Experimental investigation of shell and coil tube heat exchangers using Wilson plots[J].International Communications in Heat and Mass Transfer,2008,35(1):84-92
[10] 贾金才.几何参数对绕管式换热器传热特性影响的数值研究[J].流体机械,2011,39(8):33-37Jia Jincai.Numerical analysis geometry parameters on heat transfer for spiral wound heat exchanger[J].Fluid Machinery,2011,39(8):33-37(in Chinese)
[11] Zhang G,Zeng M,Li Y,et al.Numerical study on the thermo-hydraulic performance in the shell side of spiral-wound heat exchanger[C]//ASME 2013 Heat Transfer Summer Conference,New York:American Society of Mechanical Engineers,2013
[12] Lu X,Du X,Zeng M,et al.Experimental and numerical investigation on shell-side performance of multilayer spiral-wound heat exchangers[J].Chemical Engineering Transactions,2013,35:445-450
[13] Xin R C,Ebadian M A.The effects of Prandtl numbers on local and average convective heat transfer characteristics in helical pipes[J].Journal of Heat Transfer,1997,119(3):467-473
[14] Yang Z,Peng X,Ye P.Numerical and experimental investigation of two phase flow during boiling in a coiled tube[J].International Journal of Heat and Mass Transfer,2008,51(5):1 003-1 016
[15] Lee W H.A pressure iteration scheme for two-phase flow modeling[J].Multiphase Transport Fundamentals,Reactor Safety,Applications,1980,1:407-431
[16] Wu Z,Cai W,Qiu G,et al.Prediction of mass transfer time relaxation parameter for boiling simulation on the shell-side of LNG spiral wound heat exchanger[C]//Advances in Mechanical Engineering,New York:Hindawi Publishing Corporation,2014
[17] Orszag S A,Yakhot V,Flannery W S,et al.Renormalization group modeling and turbulence simulations[C]//Proceedings of the International Conference on Near-Wall Turbulent Flows.Arizona:Elsevier Science Publishers BV,1993 收录本刊的部分检索系统数据库