Abstract
Fluid flow and heat transfer in communicating converging and diverging channel has been numerically investigated. Channels are assumed to be at constant wall temperature and the flow is assumed to be steady state and incompressible. Since the flow and temperature fields to repeat periodically after a certain developing length, periodic boundary conditions are used for the calculations. Finite volume method is used to solve the governing differential equations numerically. Computations are performed for different values of the plate angles and Reynolds numbers. Moreover, velocity distributions along the flow field are illustrated. It was found that the converging- diverging channels destroy the boundary layer significantly and Nusselt number is found to be about 400% higher than those of parallel plate channels, whereas due to vortex formation, pressure drop increases also.
Highlights
It is very important to use compact heat exchangers in many engineering branches such as solar collectors, heaters, refrigerators, automotive and electronics equipment
Since there is not any study to compare with this system, validation of the heat transfer and friction factor of the parallel plate is performed by comparing with the previous values under similar operating conditions for hydrodynamically and thermally fully developed flow
As seen in figure 5 and 6, the present numerical results are found to be in good agreement with exact solution values obtained from the literature [27] for both the Nusselt number and the friction factor
Summary
It is very important to use compact heat exchangers in many engineering branches such as solar collectors, heaters, refrigerators, automotive and electronics equipment. For this application interrupted-wall channels were investigated, and it was showed that heat transfer can be increased using this method [5,6,7,8]. Mendes and Sparrow [9] performed experimental study for the converging and diverging tubes to determine the entry and fully developed region heat transfer coefficients, pressure distribution and friction factor at various taper angles.
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