Heat transfer and fluid flow in the microchannel cooling passages with three different types of the MTPV systems are numerically investigated. The heat transfer characteristics and thermal performance of the microchannels are analyzed using different Reynolds numbers and hydraulic diameters. Local heat transfer coefficient, total pumping power, heat transferred are obtained from the simulations and the performance is discussed in terms of heat transfer coefficient and thermal efficiency. Results indicated enhanced performance with the smaller hydraulic diameters, and slighter penalty in pumping power. The increase in Reynolds number cause an increase in the heat transfer coefficient at the expense of decreased thermal efficiency. It is also found that the highest heat transfer coefficient is expected in rod bundles microchannels. However, round microchannels have a better thermal efficiency than others.
