锯齿扁管内沸腾换热试验
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摘要
建立以等热流密度方式进行试验件加热的沸腾换热试验系统,分别对当量直径为1.28mm和1.59mm锯齿扁管内R134a工质的沸腾换热特性进行研究,试验参数范围:制冷剂质量流率为68.5~305.5kg/(m2·s),工作饱和压力为0.27~0.46 MPa,加热热流密度为9~42kW/m2。试验结果表明:相同结构的通道,当量直径小换热能力更强;热流密度和饱和压力对沸腾换热的影响与一个干度值有关。当干度小于此值时,沸腾换热系数会随着热流密度及饱和压力增大而增大;而当干度大于此值时,沸腾换热系数随着干度增大而急剧下降,热流密度和饱和压力对换热的影响较小;该干度值会随着热流密度或饱和压力增大而逐渐变小。质量流率对沸腾换热的影响与热流密度有关,随着热流密度增大,质量流率的影响趋向大干度区域。通过分析各参数对沸腾换热的影响,建立了一个预测试验工况下微小尺寸锯齿扁管的沸腾换热系数计算经验公式。
A boiling heat transfer test system is built to investigate the boiling heat transfer characteristics of two kinds of rectangular channels with offset fins,with R134 aas the working medium.The hydraulic diameters of the channels are 1.28 mm and 1.59 mm.The experiments are performed at mass flow rate of refrigerant between 68.5and 305.5kg/(m~2·s),heat flux between 9and 42kW/m~2,and saturation pressure between 0.27 and 0.45 MPa,with constant heat flux heating mode.The results show that the channel with smaller hydraulic diameter has stronger heat transfer capability.The influences of heat flux and saturation pressure on boiling heat transfer are related to a value of vapor quality.If the vapor quality is less than this value,the increase of heat flux or saturation pressure would lead to the increase of heat transfer coefficients.If the vapor quality is greater than this value,the boiling heat transfer coefficient will sharply decrease with the increase of vapor quality,and the influences of heat flux and saturation pressure will be much weaker.The value will gradually decrease with the increase of heat flux or saturation pressure.The effect of mass flow rate on boiling heat transfer is related to heat flux.With the increase of heat flux,the influence of mass flow rate tends to the region with greater vapor quality.On the basis of the analysis of these parameters,a new correlation is proposed to predict the boiling heat transfer coefficients of the small sized channels with offset fins under the experimental conditions.
A boiling heat transfer test system is built to investigate the boiling heat transfer characteristics of two kinds of rectangular channels with offset fins,with R134 aas the working medium.The hydraulic diameters of the channels are 1.28 mm and 1.59 mm.The experiments are performed at mass flow rate of refrigerant between 68.5and 305.5kg/(m~2·s),heat flux between 9and 42kW/m~2,and saturation pressure between 0.27 and 0.45 MPa,with constant heat flux heating mode.The results show that the channel with smaller hydraulic diameter has stronger heat transfer capability.The influences of heat flux and saturation pressure on boiling heat transfer are related to a value of vapor quality.If the vapor quality is less than this value,the increase of heat flux or saturation pressure would lead to the increase of heat transfer coefficients.If the vapor quality is greater than this value,the boiling heat transfer coefficient will sharply decrease with the increase of vapor quality,and the influences of heat flux and saturation pressure will be much weaker.The value will gradually decrease with the increase of heat flux or saturation pressure.The effect of mass flow rate on boiling heat transfer is related to heat flux.With the increase of heat flux,the influence of mass flow rate tends to the region with greater vapor quality.On the basis of the analysis of these parameters,a new correlation is proposed to predict the boiling heat transfer coefficients of the small sized channels with offset fins under the experimental conditions.
引文
[1]OH J T,PAMITRAN A S,CHOI K I,et al.Experimental investigation on two-phase flow boiling heat transfer of five refrigerants in horizontal small tubes of 0.5,1.5and3.0mm inner diameters[J].International Journal of Heat&Mass Transfer,2011,54(s 9-10):2080-2088.
[2]COPETTI J B,MACAGNAN M H,ZINANI F,et al.Flow boiling heat transfer and pressure drop of R-134ain a mini tube:an experimental investigation[J].Experimental Thermal&Fluid Science,2011,35(4):636-644.
[3]TIBIRICA C B,RIBATSKI G.Flow boiling heat transfer of R134aand R245fa in a 2.3mm tube[J].International Journal of Heat&Mass Transfer,2010,53(s 11-12):2459-2468.
[4]SHIFERAW D,KARAYIANNISS T G,KENNING D B R.Flow boiling in a 1.1 mm tube with R134a:Experimental results and comparison with model[J].International Journal of Thermal Sciences,2009,48(2):331-341.
[5]余建祖.换热器原理与设计[M].北京:北京航空航天大学出版社,2006:43-44.YU J Z.Principle and design of heat exchanger[M].Beijing:Beihang University Press,2006:43-44(in Chinese).
[6]DUBROVSKY E V,VASILIEV V Y.Enhancement of convective heat transfer in rectangular ducts of interrupted surfaces[J].International Journal of Heat&Mass Transfer,1988,31(4):807-818.
[7]MOCHIZUKI S,YAGI Y,YANG W J.Transport phenomena in stacks of interrupted parallel-plate surfaces[J].Experimental Heat Transfer,1987,1(2):127-140.
[8]MANGLIK R M,BERGLES A E.Heat transfer and pressure drop correlations for the rectangular offset strip fin compact heat exchanger[J].Experimental Thermal&Fluid Science,1995,10(2):171-180.
[9]PULVIRENTI B,MATALONE A,BARUCCA U.Boiling heat transfer in narrow channels with offset strip fins:Application to electronic chipsets cooling[J].Applied Thermal Engineering,2010,30(s 14-15):2138-2145.
[10]KIM B,SOHN B.An experimental study of flow boiling in a rectangular channel with offset strip fins[J].International Journal of Heat&Fluid Flow,2006,27(3):514-521.
[11]CHOI K I,PAMITRAN A S,OH C Y,et al.Boiling heat transfer of R-22,R-134a,and CO2 in horizontal smooth minichannels[J].International Journal of Refrigeration,2007,30(8):1336-1346.
[12]YEN T H,KASAGI N,SUZUKI Y.Forced convective boiling heat transfer in microtubes at low mass and heat fluxes[J].International Journal of Multiphase Flow,2003,29(12):1771-1792.
[13]BERTSCH S S,GROLL E A,GARIMELLA S V.Effects of heat flux,mass flux,vapor quality,and saturation temperature on flow boiling heat transfer in microchannels[J].International Journal of Multiphase Flow,2009,35(2):142-154.
[14]VAKILI-FARAHANI F,AGOSTINI B,THOME J R.Experimental study on flow boiling heat transfer ofmultiport tubes with R245fa and R1234ze(E)[J].International Journal of Refrigeration,2013,36(2):335-352.
[15]BERTSCH S S,GROLL E A,GARIMELLA S V.A composite heat transfer correlation for saturated flow boiling in small channels[J].International Journal of Heat&Mass Transfer,2009,52(7-8):2110-2118.
[16]凯斯W M,伦敦A L.紧凑式热交换器[M].北京:科技出版社,1997:285-326.KAYS W M,LONDON A L.Compact heat exchangers[M].Beijing:Science and Technology Press,1997:285-326(in Chinese).
[17]FELDMAN A,MARVILLET C,LEBOUCHE M.Nucleate and convective boiling in plate fin heat exchangers[J].International Journal of Heat&Mass Transfer,2000,43(18):3433-3442.
[18]LIU Z,WINTERTON R H S.A general correlation for saturated and subcooled flow boiling in tubes and annuli,based on a nucleate pool boiling equation[J].International Journal of Heat&Mass Transfer,1991,34(11):2759-2766.
[19]KEW P A,CORNWELL K.Correlations for the prediction of boiling heat transfer in small-diameter channels[J].Applied Thermal Engineering,1997,17(8-10):705-715.
[20]FANG X.A new correlation of flow boiling heat transfer coefficients based on R134adata[J].International Journal of Heat&Mass Transfer,2013,66(6):279-283.
[2]COPETTI J B,MACAGNAN M H,ZINANI F,et al.Flow boiling heat transfer and pressure drop of R-134ain a mini tube:an experimental investigation[J].Experimental Thermal&Fluid Science,2011,35(4):636-644.
[3]TIBIRICA C B,RIBATSKI G.Flow boiling heat transfer of R134aand R245fa in a 2.3mm tube[J].International Journal of Heat&Mass Transfer,2010,53(s 11-12):2459-2468.
[4]SHIFERAW D,KARAYIANNISS T G,KENNING D B R.Flow boiling in a 1.1 mm tube with R134a:Experimental results and comparison with model[J].International Journal of Thermal Sciences,2009,48(2):331-341.
[5]余建祖.换热器原理与设计[M].北京:北京航空航天大学出版社,2006:43-44.YU J Z.Principle and design of heat exchanger[M].Beijing:Beihang University Press,2006:43-44(in Chinese).
[6]DUBROVSKY E V,VASILIEV V Y.Enhancement of convective heat transfer in rectangular ducts of interrupted surfaces[J].International Journal of Heat&Mass Transfer,1988,31(4):807-818.
[7]MOCHIZUKI S,YAGI Y,YANG W J.Transport phenomena in stacks of interrupted parallel-plate surfaces[J].Experimental Heat Transfer,1987,1(2):127-140.
[8]MANGLIK R M,BERGLES A E.Heat transfer and pressure drop correlations for the rectangular offset strip fin compact heat exchanger[J].Experimental Thermal&Fluid Science,1995,10(2):171-180.
[9]PULVIRENTI B,MATALONE A,BARUCCA U.Boiling heat transfer in narrow channels with offset strip fins:Application to electronic chipsets cooling[J].Applied Thermal Engineering,2010,30(s 14-15):2138-2145.
[10]KIM B,SOHN B.An experimental study of flow boiling in a rectangular channel with offset strip fins[J].International Journal of Heat&Fluid Flow,2006,27(3):514-521.
[11]CHOI K I,PAMITRAN A S,OH C Y,et al.Boiling heat transfer of R-22,R-134a,and CO2 in horizontal smooth minichannels[J].International Journal of Refrigeration,2007,30(8):1336-1346.
[12]YEN T H,KASAGI N,SUZUKI Y.Forced convective boiling heat transfer in microtubes at low mass and heat fluxes[J].International Journal of Multiphase Flow,2003,29(12):1771-1792.
[13]BERTSCH S S,GROLL E A,GARIMELLA S V.Effects of heat flux,mass flux,vapor quality,and saturation temperature on flow boiling heat transfer in microchannels[J].International Journal of Multiphase Flow,2009,35(2):142-154.
[14]VAKILI-FARAHANI F,AGOSTINI B,THOME J R.Experimental study on flow boiling heat transfer ofmultiport tubes with R245fa and R1234ze(E)[J].International Journal of Refrigeration,2013,36(2):335-352.
[15]BERTSCH S S,GROLL E A,GARIMELLA S V.A composite heat transfer correlation for saturated flow boiling in small channels[J].International Journal of Heat&Mass Transfer,2009,52(7-8):2110-2118.
[16]凯斯W M,伦敦A L.紧凑式热交换器[M].北京:科技出版社,1997:285-326.KAYS W M,LONDON A L.Compact heat exchangers[M].Beijing:Science and Technology Press,1997:285-326(in Chinese).
[17]FELDMAN A,MARVILLET C,LEBOUCHE M.Nucleate and convective boiling in plate fin heat exchangers[J].International Journal of Heat&Mass Transfer,2000,43(18):3433-3442.
[18]LIU Z,WINTERTON R H S.A general correlation for saturated and subcooled flow boiling in tubes and annuli,based on a nucleate pool boiling equation[J].International Journal of Heat&Mass Transfer,1991,34(11):2759-2766.
[19]KEW P A,CORNWELL K.Correlations for the prediction of boiling heat transfer in small-diameter channels[J].Applied Thermal Engineering,1997,17(8-10):705-715.
[20]FANG X.A new correlation of flow boiling heat transfer coefficients based on R134adata[J].International Journal of Heat&Mass Transfer,2013,66(6):279-283.