Novel manufacturing methods allows for miniaturization of microchannel dimensions with the potential to enhance heat exchanger performance by increasing surface area per unit mass. In this thesis, microchannel heat exchanger design is analyzed to determine factors limiting effectiveness and power density. Ideal heat exchanger performance is characterized for one-pass counterflow heat exchangers with varying channel dimensions, flow regimes, and thermal conductivities. Smaller channel sizes lead to increased pressure drop and temperature gradients within the channel, necessitating low flow rates. Axial conduction is found to drive down effectiveness at low flow rates, with this effect more pronounced with decreased channel dimensions. Reducing the heat exchanger’s thermal conductivity to 1W/(m∙K) is found to reduce axial conduction. However, pressure drop still limits performance for existing designs, so optimized designs are necessary to create high performance microchannel heat exchangers. A multi-pass design consisting of stacked one-pass layers to keep pressure drop at an acceptable level is tested at various channel dimensions and flow regimes. The multi-pass design achieved an 11.2 times increase in power density and 1.08 times increase in maximum achievable effectiveness over leading commercial heat exchanger designs
