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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

A NUMERICAL STUDY ON AN EFFECT OF THE BOUNDARY LAYER ON THE HEAT TRANSFER AND PRESSURE DROP CHARACTERISTICS OF A COMPACT HEAT EXCHANGER

Get access (open in a dialog) DOI: 10.1615/IHTC11.1570
pages 215-220

摘要

As a part of a project related to the development of the design algorithm of a compact heat exchanger for the application of the electronic home appliances, the effect of the discreteness of the airflow boundary generated on the cooling fin surface on the heat transfer and pressure drop characteristics of the heat exchanger was studied numerically.
In general, there are two critical design parameters seriously considered in the design of the heat exchanger; heat transfer rate( Q ) and pressure drop coefficient CP ). Even though the higher heat transfer rate with lower pressure drop characteristics is required in a design of the heat exchanger, it is not an easy job to satisfy both conditions at the same time because these two parameters are phenomenally inversely proportional.
In here, a numerical study was carried out to understand the effect of the boundary layer generated on the fin surface on the heat transfer performance and pressure drop characteristics of the compact heat exchanger. To control the boundary layer thickness and its length along the streamline, the surface of the flat fin was modified to accelerate the heat transfer rate on the fin surface. To understand the effect of the discreted fin size(Sw) and its location(Sh) in the airflow field on the performance of the heat exchanger, the flat fin was slitted as shown in Fig. 1. The parameters incorporated in this study are the inlet air velocity (Uin). the slitted fin size( Sw ) and its location(Sh). The operating Reynolds number of the inlet air is less than 5,000 and the flow itself is quite smooth. Therefore, the airflow was assumed to be the incompressible and laminar flow. The Navier-Stokes equations with the conjugate heat transfer equation were solved to find out the temperature gradient in the flow field. A body-fitted grid generation method was incorporated for the transformation of the physical model to the computational domain. The calculation results were compared with that of a flat plate fin.