Numerical analysis of heat removal enhancement with extended surfaces

The problem of heat removal is a major issue in modern industry. The reasons for researching in this field are both to increase the performances of the target systems and to reduce the damages that high temperatures can cause. The present trend in high-tech production processes is to seek better performances by means of smaller devices. Aiming at this, it becomes necessary that all the components of the system examined are designed to supply the best possible performance. This paper faces the problem of optimising fins to enhance heat removal. The analysis so conjugates geometrical and thermo-fluid mechanical aspects. The starting point of this activity was a research, based on the Bejan's Constructal Theory, which focused on heat removal enhancement from high temperature surfaces through T-shaped fins. Initially, the same system was here numerically investigated using a CFD code. The performances computed were very similar to the reference ones. This validation allowed to apply the method to new configurations, so to develop systems further on optimised, able to remove higher thermal fluxes in the same processes. Y-shaped profiles were consequently examined, obtained by varying the angle between the two arms of the original T. The idea of performance optimisation as proposed in the reference work, was initially based on the maximisation of the dimensionless thermal conductance. This was here widened to a new definition taking into account thermal efficiency as another parameter of evaluation. It was, in fact, observed that the width reduction, typical of Y-shaped profiles with respect to T-shaped ones, enhance efficiency significantly.This new approach to heat removal optimisation suggested the realisation of arrays with multiple Y-shaped fins. Each array had the same width of the corresponding optimised T-shaped fin. This choice allowed immediate comparisons, so to evaluate the actual performance enhancements typical of multiple-fin configurations, with respect to previous configurations.