Description

This paper provides the result of an investigation about the possibility of simulating heat transfer in compact brazed plate heat exchangers (CBE) using a commercial CFD software. The simulations are performed using CFD software FLUENT 6.1 and a volume geometry corresponding to the channel in between two corrugated plates. Two different plate geometries are simulated and referred to as models CBE5a and CBE5b. The focus of the investigation is to try to reproduce with reasonable accuracy the experimentally measured differences between the two models.

First, the paper presents the governing equations and the solving method used in CFD as well as considerations about the mesh generation. Then, three geometries are simulated in total, starting with a simplified volume geometry formed between two flat plates. These first simulations provide an idea of the necessary settings for the more complicated simulations on the two volume geometries made between two corrugated plates. The k-ù SST turbulence model is used. The Reynolds number is about 3500. A tetrahedral mesh, including a boundary layer made of two rows of cells, is used. Two different boundary conditions for the heat transfer on the walls are studied. The heat flux and the wall temperature are alternatively held constant.

The results of the simulations are discussed for two different volume geometries made of corrugated plates. The best accuracy in the difference between the two corrugated models is obtained when a constant heat flux boundary condition is used. According to laboratory tests, the heat transfer characteristic of model CBE5b is 7.6% higher than that of model CBE5a. The simulations show a difference of 4.2%. It is not possible to get better accuracy when using a constant wall temperature boundary condition. Finally, simulations for testing the mesh dependency show that a coarse mesh leads to an even better estimation of the difference in heat transfer between both volume geometry models.

Units: SI

Citation: Symposium, ASHRAE Transactions, vol. 111, pt. 1, Orlando 2005

Product Details

Published:

2005

Number of Pages:

9

File Size:

1 file , 1.5 MB

Product Code(s):

D-25596