平行平板型换热器深低温交变流动传热中的变截面效应模拟与分析
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摘要
对工作在30—60 K深低温区、带有不同入口倾角的平行平板式狭缝换热器内部交变流动工质流动及传热特性开展了数值研究。在保持运行工况不变的前提下,考察换热器流道两侧入口倾角和工作温区对于传热性能的影响,分析不同变截面参数下传热性能的差异。结果表明:减小换热器入口处法兰的倾角有助于换热器入口段流体均布性,从而强化换热器内部换热,提升换热器的传热性能。该研究有助于理解变截面效应对交变流动传热特性的影响情况。
Heat exchanger performance in oscillating flow is one of the key factors that influence the efficiency of regenerative refrigerators. The flow and heat transfer characteristics of parallel-plate heat exchangers working in oscillating flow with different entrance angles have been numerically studied. With a working condition decided,the influences of entrance angle and initial temperature are numerically analyzed. The variation of heat transfer performance with cross-sectional parameter is emphasized. Results show that decreasing the flow entrance flange angle can balance the flow distribution,so that heat transfer is enhanced. This research helps to understand the variable cross-sectional area effect of heat exchanger performance in oscillating flow.
Heat exchanger performance in oscillating flow is one of the key factors that influence the efficiency of regenerative refrigerators. The flow and heat transfer characteristics of parallel-plate heat exchangers working in oscillating flow with different entrance angles have been numerically studied. With a working condition decided,the influences of entrance angle and initial temperature are numerically analyzed. The variation of heat transfer performance with cross-sectional parameter is emphasized. Results show that decreasing the flow entrance flange angle can balance the flow distribution,so that heat transfer is enhanced. This research helps to understand the variable cross-sectional area effect of heat exchanger performance in oscillating flow.
引文
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14 Marx D,Bailliet H,Valiere J. Analysis of the acoustic flow at an abrupt change in section of an acoustic waveguide using particle image velocimetry and proper orthogonal decomposition[J]. Acta Acustica United with Acustica,2008,94(4):54-65.
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16 Mohd Saat F A Z,Jaworski A J. Oscillatory flow and heat transfer within parallel-plate heat exchangers of thermoacoustic systems[C].Proceedings of the World Congress on Engineering,2013:1699-1704.
2 Komhauser AA. Gas-wall heat transfer during compression and expansion[D]. Massachusetts Institute of Technology,Doctoral Thesis,1989.
3 Gifford W E,Longsworth R C. Surface heat pumping[J]. Advances in Cryogenic Engineering,1966,11:171-181.
4 Liang J T,Ravex A,Rolland P. Study on pulse tube refrigeration.Part 1:thermodynamic non-symmetry effect[J]. Cryogenics,1996,36(2):87-93.
5 Swift G. Thermoacoustic engines[J]. Journal of Acoustic Society of America,1988,88:1145-1180.
6 Radebaugh R. Development and experimental test of an analysis model of the orifice pulse tube refrigerator[J]. Advances in Cryogenic Engineering,1987,33:851-859
7 Chen Y Y,Luo E C,Dai W. Heat transfer characteristics of oscillating flow regenerator filled with circular tubes or parallel plates[J].Cryogenics,2007,47:40-48.
8 Jensen J B,Engelbrecht K,Bahl C R H. Modeling of parallel plate regenerators with non-uniform plate distributions[J]. International Journal of Heat and Mass Transfer,2010,53:5065-5072
9 Muralidhar K,Suzuki K. Analysis of flow and heat transfer in a regenerator mesh using a non-Darcy thermally non-equilibrium model[J]. International Journal of Heat and Mass Transfer,2001,44:2493-2504.
10 Pan C Z,Zhou Y,Wang J J. CFD study of heat transfer for oscillating flow in helically coiled tube heat-exchanger[J]. Computers and Chemical Engineering,2014,69:59-65.
11 Swift G W. Thermoacoustics:A Unifying Perspective for Some Engines and Refrigerators[M]. American Institute of Physics Press,New York,2002.
12 Jaworski A J,Mao X,Mao X,et al. Entrance effects in the channels of the parallel plate stack in oscillatory flow conditions[J]. Experimental Thermal and Fluid Science,2009,33(3):495-502.
13 Mao X,Jaworski A J. Application of particle image velocimetry measurement techniques to study turbulence characteristics of oscillatory flows around parallel-plate structures in thermoacoustic devices[J].Measurement Science&Technology,2010,21(3):35-43.
14 Marx D,Bailliet H,Valiere J. Analysis of the acoustic flow at an abrupt change in section of an acoustic waveguide using particle image velocimetry and proper orthogonal decomposition[J]. Acta Acustica United with Acustica,2008,94(4):54-65.
15 Mohd Saat F A Z,Jaworski A J. CFD modelling of flow and heat transfer within parallel-plate heat exchanger in standing wave thermoacoustic system[C]. Proceedings of 19th international Congress on Sound and Vibration,Vilnius,Lithuania,2012:936-943.
16 Mohd Saat F A Z,Jaworski A J. Oscillatory flow and heat transfer within parallel-plate heat exchangers of thermoacoustic systems[C].Proceedings of the World Congress on Engineering,2013:1699-1704.