百叶窗板翅式换热器换热与阻力性能数值模拟研究
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摘要
为了解决百叶窗板翅式换热器的内部性能优化问题,通过对层流稳态下换热器燃气侧的典型流动换热单元进行建模及流动换热分析,得到了单元体内部速度、流线及温度的分布特性,并通过对换热系数、科尔本传热因子、进出口单位压降、范宁摩擦系数的比较,获得了不同燃气入口速度下翅片间距及翅片角度对换热器换热性能及流动阻力的影响。结果表明:在百叶窗翅片角度及其他尺寸参数不变时,当百叶窗间距为0. 7 mm时其换热性能最优,阻力随间距增大而减小;在翅片间距等参数不变而角度变化时,换热性能与阻力均随角度增大而增大,当百叶窗角度从15°增加至30°时,换热性能的增加幅度较为明显。
In order to solve the internal performance optimization problem of the louvered fin-fin heat exchanger,the distribution characteristics of the internal velocity field,the streamline and temperature field are obtained by modeling the typical flow heat transfer unit on the gas side of the heat exchanger under laminar steady state and analyzing the flow heat transfer. The influence of fin spacing Lpand fin angle D on heat transfer performance and flow resistance of heat exchanger are obtained by comparing the heat transfer coefficient,Colburn-Chilton j factor,the inlet and outlet unit pressure drop,and the Fanning friction factor. The numerical simulation results show that when the louver fin angle and other dimensional parameters are constant,the heat transfer performance is optimal when the louver spacing is Lp= 0. 7 mm,and the resistance decreases with the increase of the pitch. With constant the fin spacing,as the angle changes,the heat transfer performance and resistance increase with the increase of the angle. As the angle of the louver increases from 15° to 30°,the heat transfer performance increases clearly. The simulation results have evident guiding significance for the design optimization of this type of heat exchanger.
In order to solve the internal performance optimization problem of the louvered fin-fin heat exchanger,the distribution characteristics of the internal velocity field,the streamline and temperature field are obtained by modeling the typical flow heat transfer unit on the gas side of the heat exchanger under laminar steady state and analyzing the flow heat transfer. The influence of fin spacing Lpand fin angle D on heat transfer performance and flow resistance of heat exchanger are obtained by comparing the heat transfer coefficient,Colburn-Chilton j factor,the inlet and outlet unit pressure drop,and the Fanning friction factor. The numerical simulation results show that when the louver fin angle and other dimensional parameters are constant,the heat transfer performance is optimal when the louver spacing is Lp= 0. 7 mm,and the resistance decreases with the increase of the pitch. With constant the fin spacing,as the angle changes,the heat transfer performance and resistance increase with the increase of the angle. As the angle of the louver increases from 15° to 30°,the heat transfer performance increases clearly. The simulation results have evident guiding significance for the design optimization of this type of heat exchanger.
引文
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[12]张丽娜,高长银,刘敏珊.新型百叶窗翅片对流换热特性研究[J].压力容器,2014,31(5):46-50.ZHANG Li-na,GAO Chang-yin,LIU Min-shan. Study on convec-tive heat transfer characteristics of new type of louver fins[J].Pressure Vessel,2014,31(5):46-50.
[13]牛玲,周俊杰.基于共轭传热的百叶窗翅片换热器操作参数优化设计[J].工程热物理学报,2015(6):1294-1297.NIU Ling,ZHOU Jun-jie. Optimum design of operating parame-ters of louver fin heat exchanger based on conjugate heat transfer[J]. Journal of Engineering Thermophysics,2015(6):1294-1297.
[14]杨凤叶,赵鹏飞,周光辉.新型变角度百叶窗翅片换热器的性能研究[J].低温与超导,2015,43(6):84-88.YANG Feng-ye,ZHAO Peng-fei,ZHOU Guang-hui. Study on theperformance of a new variable angle louver fin heat exchanger[J]. Cryogenic and Superconductor,2015,43(6):84-88.
[15] PERROTIN T,CLODIC D. Thermal-hydraulic CFD study in lou-vered fin-and-flat-tube heat exchangers[J]. International Journalof Refrigeration,2004,27(4):422-432.
[2] JANG J Y,CHEN C C. Optimization of louvered-fin heat exchang-er with variable louver angles[J]. Applied Thermal Engineering,2015,91:138-150.
[3] KARTHIK P,KUMARESAN V,VELRAJ R. Experimental andparametric studies of a louvered fin and flat tube compact heat ex-changer using computational fluid dynamics[J]. Alexandria Engi-neering Journal,2015,54(4):905-915.
[4] ERBAY L B,UGURLUBILEK N,ALTUN,et al. Numerical in-vestigation of the air-side thermal hydraulic performance of a lou-vered-fin and flat-tube heat exchanger at low Reynolds numbers[J]. Heat Transfer Engineering,2017,38(6):627-640.
[5] CHANG Y J,WANG C C. A generalized heat transfer correlationfor Iouver fin geometry[J]. International Journal of heat and masstransfer,1997,40(3):533-544.
[6] PARK J S,KIM D R,LEE K S. Local frost behaviors of a scaled-up louvered fin heat exchanger[J]. International Journal of Heatand Mass Transfer,2015,89:1127-1134.
[7] CHEN T,WANG J,PENG W. Flow and heat transfer analyses of aplate-fin heat exchanger in an HTGR[J]. Annals of Nuclear Ener-gy,2017,108:316-328.
[8] RYU K,LEE K S. Generalized heat-transfer and fluid-flow correla-tions for corrugated louvered fins[J]. International Journal of Heatand Mass Transfer,2015,83:604-612.
[9]卢洪波,崔国民,李美玲.多股流板翅式换热器温度交叉的数值分析[J].热能动力工程,2002(6):611-613,654-655.LU Hong-bo,CUI Guo-min,LI Mei-ling. Numerical analysis oftemperature crossing of multi-flower plate-fin heat exchangers[J].Journal of Engineering for Thermal and Power,2002(6):611-613,654-655.
[10] KIM T K,KANG H C,LEE J S. A porosity model for flow resist-ance calculation of heat exchanger with louvered fins[J]. Journalof Mechanical Science and Technology,2016,30(4):1943-1948.
[11]张丽娜,刘敏珊,董其伍.梭形百叶窗结构内传热强化数值分析[J].工程热物理学报,2012,33(2):323-325.ZHANG Li-na,LIU Min-shan,DONG Qi-wu. Numerical analysisof heat transfer enhancement in a shuttle-shaped louver structure[J]. Journal of Engineering Thermophysics,2012,33(2):323-325.
[12]张丽娜,高长银,刘敏珊.新型百叶窗翅片对流换热特性研究[J].压力容器,2014,31(5):46-50.ZHANG Li-na,GAO Chang-yin,LIU Min-shan. Study on convec-tive heat transfer characteristics of new type of louver fins[J].Pressure Vessel,2014,31(5):46-50.
[13]牛玲,周俊杰.基于共轭传热的百叶窗翅片换热器操作参数优化设计[J].工程热物理学报,2015(6):1294-1297.NIU Ling,ZHOU Jun-jie. Optimum design of operating parame-ters of louver fin heat exchanger based on conjugate heat transfer[J]. Journal of Engineering Thermophysics,2015(6):1294-1297.
[14]杨凤叶,赵鹏飞,周光辉.新型变角度百叶窗翅片换热器的性能研究[J].低温与超导,2015,43(6):84-88.YANG Feng-ye,ZHAO Peng-fei,ZHOU Guang-hui. Study on theperformance of a new variable angle louver fin heat exchanger[J]. Cryogenic and Superconductor,2015,43(6):84-88.
[15] PERROTIN T,CLODIC D. Thermal-hydraulic CFD study in lou-vered fin-and-flat-tube heat exchangers[J]. International Journalof Refrigeration,2004,27(4):422-432.