Simulation of mems heat exchanger with various working fluids

Abstract

The introduction of MEMS heat exchanger has established a new era in the history of heat transfer in micro scale systems. This study is based on an analysis conducted using commercial finite element package. During the analysis different parameters such as temperature of wall, fluid inlet velocity and other fluid properties have been used as input parameters for solving the governing equations and boundary conditions. After solving the problem in finite element method, outlet mean temperature has been obtained which is then used for further calculation to evaluate heat transfer behaviour of fluids. The aim of this simulation is to find a substitute of conventional working fluids used as coolant for MEMS heat exchanger and also to evaluate performance of fluids for different geometry. Usually water and air is more preferable as coolant for their low cost and availability. But they have some disadvantages too such as dust in content, forming rust in metal contact etc. So a second option is needed such that the conventional fluids can be substituted. Freon II has shown the highest outlet mean temperature during the study. Freon 113 and ammonia has also shown a good percentage of increment of heat transfer when surface area is increased. Moreover in this analysis, emphasis is also given on the effect of geometry on the performance of different fluids. It is apparent from this work that rectangular surface heat exchanger shows highest outlet mean temperature as well as heat transfer of fluids in comparison to other geometry. Therefore it may be suggested that rectangular surface may be used instead of wavy surface as it is also easy to manufacture. This work is an extension of a tutorial which showed the calculation of outlet mean temperature of water for wavy surface MEMS heat exchanger with pitch 0.95 mm. The rest of the work done in this analysis is based on the need of evaluation of performance of fluids as well as geometry. The overall results obtained from this work are quite satisfactory. It is thought to be helpful for the researchers in this field.