Thermodynamic Analysis of Efficiency- NTU Parameters for Parallel Flow Type Heat Exchanger under the Effect of External Heat LeakAuthor : Roopesh Tiwari and Govind Maheshwari
Volume 7 No.1 January-June 2018 pp 59-65
The work presented here analyses theoretically a parallel flow type heat exchanger which is subjected to external heat leak, from the cold fluid side or from the hot fluid side. Efficiency-NTU relations are developed and the results obtained are presented graphically, reflecting the effect of heat capacity ratios and the heat leak on the efficiency of the heat exchanger. The graphs follow the similar pattern with increasing heat capacity ratios. Also, as the heat leak is increased, the graphs show opposite behavior when the minimum heat capacity is on the hot side to that when the minimum capacity is on the cold side. The derived expressions are reduced to the classical effectiveness-efficiency-NTU relations for the parallel flow type heat exchangers as the heat leak approaches zero.
Heat exchanger, Effectiveness, Efficiency, Heat leak, Heat capacity ratio
 A. Fakheri, “Arithmetic Mean Temperature Difference and the Concept of Heat Exchanger Efficiency”, Proceedings of the 2003 ASME Summer Heat Transfer Conference, July 21-23, 2003, Paper No. HT2003-47360
 A. Fakheri, “Heat Exchanger efficiency”, ASME, Vol. 129, pp. 1268-1276, 2007.
 A. Fakheri, “The Shell and Tube Heat Exchanger Efficiency and its Relation to Effectiveness”, Proceedings of the 2003 ASME International Mechanical Engineering Congress and Exposition, November 16-21, 2003.
 A. Fakheri, “Thermal Efficiency of the Cross Flow Heat Exchanger”, Proceedings of the 2006 ASME International Mechanical Engineering Congress and Exposition, November 5-10, 2006.
 F. A. McClintock,“The Design of Heat Exchangers for Minimum Irreversibility”,Presented at the ASME, Annual Meeting Paper No. 51-A-108, 1951.
 A. Bejan, “Concept of Irreversibility in Heat Exchanger Design: Counterflow Heat Exchangers for Gas-to-Gas Applications”,ASME J. Heat Transfer, Vol.99, No. 3, pp. 374–380, 1977.
 S. Accves-Saborio, J. Ranasinghe and G. M. Reistad, “Extension to the Irreversibility Minimization Analysis Applied to Heat Exchangers”, ASME J.HeatTransfer,Vol. 111, No. 1, pp. 29-36, 1989.
 R. K. Shah and T. Skiepo, “Entropy Generation Extrema and Their Relationship With Heat Exchanger Effectiveness- Number of Transfer Unit Behaviour for Complex Flow Arrangements”, ASME J. Heat Transfer, Vol. 126, No. 6, pp. 994-1002, 2004.
 G. Maheshwari, A. I. Khandwawala and S. C. Kaushik,“A comparative performance analysis of an endoreversible heat engine with thermal reservoir of finite heat capacitance under maximum power density and maximum powerconditions”, International Journal of Ambient Energy, Vol. 26, No. 3, pp. 147-154,2005.
 K. Chowdhury and S. Sarangi,“Performance of Cryogenic Heat Exchangers with Heat Leak from the Surroundings”, Advances inCryogenic Engineering, Vol. 29, pp. 273–280, 1984.
 R. F. Barron, “Effect of Heat Transfer from Ambient to Cryogenic Heat Exchanger Performance”, Advances in Cryogenic Engineering,Vol. 29, pp. 265–272, 1984.
 S. Al-Dini and S. Zubair, “Effectiveness-NTU Relations for Parallel Flow Heat Exchangers Subjected to Heat Leak from outside, Heat Transfer Engineering, Vol. 29, No. 5, pp. 475-483, 2008.