Thermal Transfer Performance of Parallel Flow Heat Exchangers under Frost Conditions

Abstract

Abstract: The parallel flow heat exchanger’s thermal transfer performance under frost conditions was investigated. The heat transfer area and overall surface efficiency change as the frost grows. The airside heat transfer coefficient was also calculated using logarithmic-mean temperature difference (LMTD) method. The result shows that when the frost thickness grows to 0.4 mm, the heat transfer area decreases by 18%, and the air side surface efficiency decreases by 17.42%~24.78%. Moreover, the reduction of the heat transfer coefficient is an important cause to the decline of heat exchanger performance. The heat transfer coefficient decreases about 50% in the tests, while louver gap blockage mainly contributes to the decrease of heat transfer coefficient.

Key words: parallel flow heat exchanger, frost, heat transfer area, surface efficiency, heat transfer coefficient

CLC Number:

TB 61

LIANG Yuan-Yuan, XU Bo, CHEN Jiang-Ping. Thermal Transfer Performance of Parallel Flow Heat Exchangers under Frost Conditions[J]. Journal of Shanghai Jiaotong University, 2013, 47(04): 674-678.

References

［1］Padhmanabhan S K, Cremaschi L, Fisher D E. Comparison of frost and defrost performance between microchannel coil and finandtube coil for heat pump systems［J］. International Refrigeration and Air Conditioning and Refrigration, 2011,19(4):273284.
［2］Xia Y, Jacobi A M. An exact solution to steady heat conduction in a twodimensional slab on a onedimensional fin: Application to frosted heat exchangers ［J］. Heat and Mass Transfer, 2004, 47(14):33173326.
［3］Xia Y, Jacobi M A. Airside data interpretation and performance analysis for heat exchangers with simultaneous heat and mass transfer: Wet and frosted surfaces［J］. Heat and Mass Transfer, 2005,48(2526): 50895102.
［4］Xia Y, Jacobi A M. A model for predicting the thermalhydraulic performance of louveredfin, flattube heat exchangers under frosting conditions［J］. Refrigeration, 2010, 33(2): 321333.
［5］Padhmanabhan S K, Fisher D E, Cremaschi L, et al. Modeling nonuniform frost growth on a finandtube heat exchanger［J］. Refrigeration, 2011, 34(8): 20182030.
［6］Shao Liangliang, Yang Liang, Zhang Chunlu. Comparison of heat pump performance using finandtube and microchannel heat exchangers under frost conditions［J］. Applied Energy, 2010, 87(4): 11871197.
［7］Huang JengMin, Hsieh WenChien, Ke XinJi, et al. The effects of frost thickness on the heat transfer of finned tube heat exchanger subject to the combined influence of fan types［J］. Applied Thermal Engineering, 2008, 28(7): 728737.
［8］罗超，黄兴华，陈江平. 不同环境参数对间冷式冰箱蒸发器结霜换热性能的影响［J］. 制冷学报，2008,29(1):1722.
LUO Chao, HUANG Xinghua, CHEN Jiangping. Effect of different parameters on frosting of evaporator in frost free refrigerator［J］. Journal of Refrigeration, 2008,29(1):1722.
［9］廖云虎，丁国良，林恩新, 等. 翅片管换热器结霜过饱和模型［J］.上海交通大学学报，2008,42(3): 399403.
LIAO Yunhu, DING Guoliang, LIN Enxin ,et al. Supersaturation model of finned tube heat exchangers under frosting conditions［J］. Journal of Shanghai Jiaotong University, 2008,42(3):399403.
［10］董军启，陈江平，袁庆丰, 等. 板翅换热器平直翅片的传热与阻力性能试验［J］.农业机械学报, 2007,38(8): 5356.
DONG Junqi, CHEN Jiangping, YUAN Qingfeng, et al. Flow and heat transfer on compact smooth fin surfaces［J］. Transactions of the Chinese Society for Agricultural Machinery, 2007,38(8): 5356.

[1]	WANG Yikai，YE Zuliang，PAN Zudong，ZHAO Jianfeng，HU Bin，CAO Feng. Hot-Gas Bypass Defrosting Method and Analysis of Defrosting Time for Transcritical CO2 Heat Pump [J]. Journal of Shanghai Jiaotong University, 2019, 53(11): 1367-1374.
[2]	WU Zhijian1,2,3,CHEN Tuo4，MA Wei5. Analysis of LongTerm Deformation of Railway Embankment at Repeated Train Load in Permafrost Regions [J]. Journal of Shanghai Jiaotong University, 2015, 49(07): 929-934.
[3]	NIU Fu-jun1,3 (牛富俊), SUN Hong2* (孙红), GE Xiu-run2 (葛修润), ZHANG Jin-zhao3 (章金钊). Temperature Adjustment Mechanism of Composite Embankment with Perforated Ventilation Pipe and Blocky Stone [J]. Journal of shanghai Jiaotong University (Science), 2013, 18(6): 729-732.
[4]	DONG Jian-Kai-1, JIANG Yi-Qiang-1, YAO Yang-1, YAN Ling-2. Experimental Study on Characteristic of Thermal Energy Storage Defrosting for Air Source Heat Pump Using Sub-cooling Energy of Refrigerant [J]. Journal of Shanghai Jiaotong University, 2012, 46(10): 1604-1608.
[5]	KANG Jia, HAN Hua, GU Bo, QIU Feng. Air-Side Heat Transfer Modeling Suitable for Fault Detection and Diagnosis of Refrigeration and Air-Conditioning Systems [J]. Journal of Shanghai Jiaotong University, 2011, 45(09): 1368-1373.