针对一维密闭腔体中过热液体R134a的传热过程建立数学模型，并进行数值模拟研究。对计算区域左边界进行阶跃温差为1 K的等温加热，通过求解可压缩流体控制方程组，成功捕捉到流体内部存在的活塞效应，计算出其当量热导率，并分析过热程度对活塞效应的影响规律。结果表明：过热液体R134a中活塞效应当量热导率显著高于工质自身热导率，利用活塞效应可传递更高的热流密度，并实现更高的传热速率。
In this paper, a model of one-dimensional cavity filled with meta-stable superheated liquid R134a is built to investigate influence of the piston effect (PE). Numerical simulation method is used in boundary condition of a temperature jump. The PE is caught in the superheated liquid by solving energy transport equation of compressible fluid. Then the equivalent thermal conductivity of PE is calculated. Furthermore, the influence of liquid superheat degree on piston effect is investigated. The higher the superheat degree is, the stronger the PE effect is. In conclusion, the piston effect is capable of carrying higher heat flux and speeding up thermal equilibrium in superheated liquid of R134a. The equivalent thermal conductivity of PE is obviously superior to pure heat conduction, and the equivalent thermal conductivity of PE is tripled.
[1] Farouk B, Oran E S, Fusegi T. Numerical study of thermoacoustic waves in an enclosure[J]. AIP Physics of fluids, 2000, 12(5):1052-1061.
[2] Hasan N, Farouk B. Fast heating induced thermoacoustic waves in supercritical fluids:experimental and numerical studies[J]. Journal of Heat Transfer, 2013, 135(8):1701-1712.
[3] Shen B, Zhang P. An overview of heat transfer near the liquid-gas critical point under the influence of the piston effect:phenomena and theory[J]. International Journal of Thermal Sciences, 2013, 71:1-19.
[4] 毛宇飞,郭烈锦.超临界水活塞效应传热现象的数值模拟[J].自然科学进展, 2006, 16(4):457-462.
[5] Zappoli B, Beysen D, Guenoun P. Anomalies of heat transport in near critical fluids under weightlessness[J]. Advances in Space Research, 1991, 11(7):269-276.
[6] 李玉华,占丽媛,姜玉雁,等.液相工质中热声效应数值模拟研究[J].工程热物理学报, 2014, 35(11):2274-2277.
[7] 占丽媛,李玉华,姜玉雁,等.密闭二维腔体内水中热声波的数值模拟[J].化工学报, 2014, 65(S1):32-38.
[8] Miura Y,Yoshihara S, Ohnishi M. High-speed observation of the piston effect near the gas-liquid critical point[J]. Physical Review E, 2006, 74(1):010101.
[9] Lin Y, Farouk B. Experimental and numerical studies of thermally induced acoustic waves in an enclosure[J]. Journal of Thermophysics and Heat Transfer, 2008, 22(1):105-114.
[10] 刘杰,李廷勋,裴念强,等.两相冷却系统过热现象与启动温度关系分析[J].制冷学报, 2007, 28(6):23-28.
[11] Nichele J, Alves S L B, Borges I. Equation of state for near critical argon obtained via molecular dynamics[J]. High Temperatyre High Pressure, 2014, 43(5):385-400.
[12] Straub J, Eicher L, Haupt A. Dynamic temperature propagation in a pure fluid near its critical point observed under microgravity during the German Spacelab Mission D-2[J]. Physical Review E, 1995, 51(6):5556-5563.
[13] Nakano A, Shiraishi M. Piston effect in supercritical nitrogen around the pseudo-critical line[J]. International Communications in Heat and Mass Transfer, 2005, 32(9):1152-1164.
[14] Tillner-Roth R, Baehr H D. An international standard formulation for the thermodynamic properties of 1,1,1,2-tetrafluoroethane (HFC-134a) for temperatures from 170K to 455K and pressures up to 70MPa[J]. Journal of Physical and Chemical Reference Data, 1994, 23(5):657-729.
[15] Huang Y, Bau H H. Thermoacoustic waves in a confine medium[J]. International Journal of Hear Mass Transfer, 1997, 40(2):407-419.
[16] Gross U, Song Y W, Hahne E. Thermal conductivity of the new refrigerants R134a,R152a and R123 measured by the transient hot-wire method[J]. International Journal of Thermophysics, 1992, 13(6):957-983.
[17] Baginsky A V, Shipitsyna A S. Thermal conductivity and thermal diffusivity of the R134a refrigerant in the liquid state[J]. Thermophysics and Aeromechanics, 2009, 16(2):267-273.
