A power electronics assembly , comprising: one or more power electronics devices ; and a heat exchanger to which the one or more power electronics devices are mounted, the heat exchanger comprising : an inlet manifold and an outlet manifold ; and one or more fluid pathways extending connecting the inlet manifold and the outlet manifold , the heat exchanger configured to transfer thermal energy from the one or more power electronics devices into a flow of fluid passing through the one or more fluid pathways ; wherein the one or more fluid pathways include one or more internal enhancements and channel configurations to enhance thermal energy transfer by promoting boiling of the flow of fluid and to reduce the pressure drop in the pathways under a two-phase flow condition; wherein the flow of fluid is a flow of liquid refrigerant diverted from a condenser of a heating, ventilation, and air conditioning (HVAC) system ; wherein the one or more internal enhancements include one or more inclined notches formed in the one or more fluid pathways , the one or more inclined notches extending unbroken around an entire internal perimeter of the fluid pathway; the one or more inclined notches having a rectangular cross-sectional shape and being oriented to extend across the fluid pathway relative to the direction of the flow of fluid along the fluid pathway. one or more power electronics devices ; and a heat exchanger to which the one or more power electronics devices are mounted, the heat exchanger comprising : an inlet manifold and an outlet manifold ; and one or more fluid pathways extending connecting the inlet manifold and the outlet manifold , the heat exchanger configured to transfer thermal energy from the one or more power electronics devices into a flow of fluid passing through the one or more fluid pathways ; wherein the one or more fluid pathways include one or more internal enhancements and channel configurations to enhance thermal energy transfer by promoting boiling of the flow of fluid and to reduce the pressure drop in the pathways under a two-phase flow condition; an inlet manifold and an outlet manifold ; and one or more fluid pathways extending connecting the inlet manifold and the outlet manifold , the heat exchanger configured to transfer thermal energy from the one or more power electronics devices into a flow of fluid passing through the one or more fluid pathways ; wherein the one or more fluid pathways include one or more internal enhancements and channel configurations to enhance thermal energy transfer by promoting boiling of the flow of fluid and to reduce the pressure drop in the pathways under a two-phase flow condition; wherein the flow of fluid is a flow of liquid refrigerant diverted from a condenser of a heating, ventilation, and air conditioning (HVAC) system ; wherein the one or more internal enhancements include one or more inclined notches formed in the one or more fluid pathways , the one or more inclined notches extending unbroken around an entire internal perimeter of the fluid pathway; the one or more inclined notches having a rectangular cross-sectional shape and being oriented to extend across the fluid pathway relative to the direction of the flow of fluid along the fluid pathway. <EOS>