Optimal rectangular microchannel design, using simulated annealing, unified particle swarm and spiral algorithms, in the presence of spreading resistance

This article focuses on the solution of the mathematical model of a rectangular microchannel through three algorithms: SA (Simulated Annealing), UPSO (Unified Particle Swarm Optimization) and SO (spiral Optimization). The criterion of minimum entropy generation was used for constructing the model, which includes the effect of the thermal spreading resistance. This type of thermal resistance occurs whenever a smaller heat source (e.g. the chip) comes in contact with the base of a larger heat transfer element (e.g. the heat sink). This simulation work was split into two stages. The first one considered different scenarios for a silicon heat sink using air as a working fluid. In this case, volume flow rates between 4.0 and 4.5 x 10(-3) m(3)/s exhibited lower values of entropy generation rate. The second stage considered three materials (silicon, aluminum, and copper) and two worlcing fluids (air and ammonia gas). We found, for this particular set of conditions, that entropy generation becomes minimum, for a given material and working fluid, as long as a volume flow rate of 4.5 x 10(-3) m(3)/s is used. Even so, the best practical configuration found was an aluminum heat sink with ammonia gas. For all the simulations, a marked effect due to the spreading resistance was found, typically ignored in real life applications. (C) 2015 Elsevier Ltd. All rights reserved.