Computational Modeling of Counter Flow Heat Exchanger for LMTD Analysis

Abstract

: In the present work we have investigated the heat transfer, log mean temperature difference and thermo-physical characteristics of a counter flow heat exchanger. The experiments were carried out in counter current mode and water is taken as the fluid. While the hot fluid is flowing in the inner tube and cold fluid is flowing in the outer tube. Due to low mass flux in the core of the heat exchanger, the tubes are not uniformly heated. The CFD simulations were in agreement with the present experimental data from the existing literature [8]. In case of literature data a reasonable comparison was found even though the boundary conditions in the present work were different. The Realizable k-epsilon turbulence model is chosen for the flow investigation. Computational fluid dynamics and heat transfer simulations are conducted for a novel shell-tube type heat exchanger. The heat exchanger consists of tube with a narrow slot oriented in the stream-wise direction. LMTD of the counter flow heat exchanger is comes out to be 29.65 while decreasing the cold fluid temperature with an average error of 8.5% with the existing literature. But while increasing the hot inlet fluid temperature the LMTD rises more rapidly along the length with an average of 26.58 and with a percentage error of 8.9%.