Research Article CFD Simulation of Flow Distribution in the Header of Plate-Fin Heat Exchangers The flow distribution through a plate-fin heat exchanger is studied by using a computational fluid dynamics (CFD) code, FLUENT. The flow distribution through any heat exchanger affects its performance. In designing a heat exchan- ger, it is assumed that the fluid is uniformly distributed through the heat exchan- ger core. In practice, however, it is impossible to distribute fluid uniformly, be- cause of an improper inlet configuration, imperfect design, and a complex heat transfer process. The CFD simulation of the flow distribution in the header of a conventional plate-fin heat exchanger is presented. It is found that the flow mal- distribution is very serious in the y-direction of the header. A modified header is proposed and simulated using CFD. The modified header configuration has a more uniform flow distribution than the conventional header configuration. Hence, the efficiency of the modified heat exchanger is seen to be higher than that of the conventional heat exchanger. Keywords: CFD, Plate-fin heat exchanger, Flow distribution, Header configuration Received: March 20, 2007; revised: July 12, 2007; accepted: July 17, 2007 DOI: 10.1002/ceat.200700180 1 Introduction Recent studies on heat exchangers have concentrated on the development of high performance compact devices to reduce energy consumption as well as material costs. Plate-fin heat ex- changers, as one of the most compact heat exchangers with high performance, are widely used in the aerospace and chemi- cal engineering industries, and in artificial organs. In designing a heat exchanger, it is assumed that the fluid is uniformly dis- tributed through the heat exchanger core. In practice, however, it is impossible to distribute fluid uniformly, because of an im- proper inlet configuration, imperfect design, and a complex heat transfer process. Gross flow maldistribution and passage to passage nonuniformity of flow exist in plate-fin heat ex- changers. Due to these complexities, the flow in heat exchangers has only been investigated experimentally and analytically [1–5]. Ranganayakulu and Seetharamu [2] carried out an analysis of the effects of inlet fluid flow nonuniformity on the thermal performance and pressure drop in a cross-flow plate-fin heat exchanger by using FEM. Mueller and Chiou [6] summarized various types of flow maldistribution in heat exchangers and discussed the reasons leading to flow maldistribution. Lalot and Florent [7] used the computer code STAR-CD to study the gross flow maldistribution in an electrical heater. They found that reverse flows would occur for poor header design and that a perforated grid can improve the fluid flow distribu- tion. However, only a few others have studied the fluid flow maldistribution in heat transfer equipment using the compu- tational fluid dynamics simulation technique [8]. Jiao et al. [9] investigated the combined effects of the distributor inlet angle, configuration parameter and header configuration on the flow velocity distribution, both experimentally and theoretically. Wen and Li [10] studied the flow distribution and its improve- ment in the header of a plate-fin heat exchanger. They sug- gested an improved header configuration with a punched baf- fle. Wen et al. [11] studied the flow patterns in the entrance of a plate-fin heat exchanger both experimentally and numeri- cally. The turbulence flow structure inside the entrance of a plate-fin heat exchanger was characterized by CFD simulation and particle image velocimetry (PIV) experiments under simi- lar conditions. Experimental investigations for the improve- ment of the header configuration in a plate-fin heat exchanger have been performed by Wen et al. [12]. The authors used PIV to study flow characteristics in the header of a plate-fin heat exchanger. Experiments with their improved and optimized header design indicate that the temperature is distributed more uniformly which results in higher effectiveness. The CFD simulation technique can provide the flexibility to construct computational models that are easily adapted to a wide variety of physical conditions without the requirement to © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim http://www.cet-journal.com Kailas L. Wasewar 1 Santosh Hargunani 2 Praveen Atluri 2 Naveen Kumar 3 1 Department of Chemical Engineering, Indian Institute of Technology, Roorkee, India. 2 Mechanical Engineering Group, Birla Institute of Technology and Science, Rajastan, India. 3 Chemical Engineering Group, Birla Institute of Technology and Science, Rajastan, India. – Correspondence: K. L. Wasewar (k_wasewar@rediffmail.com and klw73fch@iitr.ernet.in), Department of Chemical Engineering, Indian Institute of Technology (IIT), Roorkee – 247667, India. 1340 Chem. Eng. Technol. 2007, 30, No. 10, 1340–1346