Partial boiling in mini and micro-channels

A process of removing heat from an exothermic process, comprising:

• conducting an exothermic process in a process channel;
• removing heat from the exothermic process in the process channel to an adjacent minichannel or adjacent microchannel;
• wherein the adjacent minichannel or adjacent microchannel comprises an interior wall surface that is a surface on a channel wall that separates the adjacent minichannel or adjacent microchannel from the process channel;
• wherein the adjacent minichannel or adjacent microchannel comprises a barrier at an entrance area of the minichannel or microchannel, wherein the adjacent minichannel or adjacent microchannel comprises a cross-sectional area perpendicular to flow through the minichannel or microchannel, and wherein the barrier creates an opening in the direction of flow through the minichannel or microchannel that is greater than 10% of the cross-sectional area of the minichannel or microchannel;
• passing a coolant fluid through the adjacent minichannel or adjacent microchannel at an average shear stress of the fluid at the wall in the adjacent minichannel or adjacent microchannel for a length of at least 1 cm, either measured or calculated, of at least 1 Pascals (Pa);
• and
• partially boiling the coolant fluid for a length of at least 15 cm as it passes through the adjacent minichannel or adjacent microchannel.