Analysis of a new cross flow heat exchanger flow arrangement e Extension to several rows Luben Cabezas-Gómez a, * , Hélio Aparecido Navarro b , José Maria Sáiz-Jabardo c , Sergio de Morais Hanriot a , Cristiana Brasil Maia a a Mechanical Engineering Department, Pontifícia Universidade Católica de Minas Gerais, PUC Minas, Av. Dom José Gaspar, 500, Prédio 10, Coração Eucarístico, CEP 30535-910, Belo Horizonte, MG, Brazil b Mechanical Engineering Department, Escola de Engenharia de São Carlos, Universidade de São Paulo, Av. Trabalhador São-carlense, 400-Centro, CEP 13566-590, São Carlos, SP, Brazil c Escuela Politécnica Superior, Universidad de la Coruña, Mendizábal s/n Esteiro, 15403 Ferrol, Coruña, Spain article info Article history: Received 28 July 2011 Received in revised form 29 December 2011 Accepted 3 January 2012 Available online 31 January 2012 Keywords: Cross flow heat exchangers Thermal effectiveness Heat exchanger efficiency Entropy generation Entransy dissipation number Numerical simulation abstract The present paper presents a theoretical analysis of a cross flow heat exchanger with a new flow arrangement comprehending several tube rows. The thermal performance of the proposed flow arrangement is compared with the thermal performance of a typical counter cross flow arrangement that is used in chemical, refrigeration, automotive and air conditioning industries. The thermal performance comparison has been performed in terms of the following parameters: heat exchanger effectiveness and efficiency, dimensionless entropy generation, entransy dissipation number, and dimensionless local temperature differences. It is also shown that the uniformity of the temperature difference field leads to a higher thermal performance of the heat exchanger. In the present case this is accomplished thorough a different organization of the in-tube fluid circuits in the heat exchanger. The relation between the recently introduced “entransy dissipation number” and the conventional thermal effectiveness has been obtained in terms of the “number of transfer units”. A case study has been solved to quantitatively to obtain the temperature difference distribution over two rows units involving the proposed arrangement and the counter cross flow one. It has been shown that the proposed arrangement presents better thermal performance regardless the comparison parameter. Ó 2012 Elsevier Masson SAS. All rights reserved. 1. Introduction The main objective of the present paper is to perform a theo- retical characterization of a new flow arrangement of a cross flow heat exchanger with potential applications in the refrigeration and automotive industries. The new flow arrangement has recently been proposed by Cabezas-Gómez et al. [1,2] based on the general guidelines developed by Guo et al. [3]. Those authors examined the implications and applicability of the so-called “uniformity prin- ciple” of the temperature difference field (TDF) in connection with the heat exchanger effectiveness. They tested several flow arrangements and demonstrated both theoretically and experi- mentally that a heat exchanger with a more uniform TDF distri- bution holds higher effectiveness values. According to [3], the thermal effectiveness of a cross flow heat exchanger could be upgraded by a more uniform TDF. This can be attained in two different ways: either redistributing the heat transfer area or rearranging the connections between tubes. Certain questions related to the latter procedure have been addressed in the present study aiming at the development of a new tube-side flow distri- bution that ultimately could attain an enhancement of the heat exchanger thermal performance. The initial configuration intro- duced in [1] and [2] has been further extended to cross flow heat exchangers with more than two tube rows. A theoretical analysis has demonstrated that the proposed arrangement leads to a higher thermal effectiveness and heat exchanger efficiency in addition to less entropy generation for a wide range of NTU values. The improved performance of the new flow arrangement has been cross-checked against the new concept of “entransy dissipation”, recently proposed by Guo and coworkers [4e6] with positive results. It has also been shown that the idea behind the uniform TDF is closely related to other thermal performance characteriza- tion norms based on the Second Law of Thermodynamics. One such a norm is the so-called HERN (Heat Exchanger Reversibility Norm), * Corresponding author. Tel.: þ55 31 33194301; fax: þ55 31 33194910. E-mail addresses: luben@pucminas.br (L. Cabezas-Gómez), han@sc.usp.br (H.A. Navarro), mjabardo@cdf.udc.es (J.M. Sáiz-Jabardo), hanriot@pucminas.br (S.M. Hanriot), cristiana@pucminas.br (C.B. Maia). Contents lists available at SciVerse ScienceDirect International Journal of Thermal Sciences journal homepage: www.elsevier.com/locate/ijts 1290-0729/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.ijthermalsci.2012.01.001 International Journal of Thermal Sciences 55 (2012) 122e132