Abstract: A highly compact plate-fin catalytic combustion heat exchanger (CCHE) derived from plate-fin heat exchanger,which coupled exothermic reaction with evaporation was proposed.The configuration of plate-fin offered a high degree of compactness，minimized heat transport resistance and favored scale-up.Uniform concentration distributions contributed to further enhancement of the heat efficiency of CCHE.A porous media model was adopted to study the concentration distributions under diverse space velocities and pressure-outlet positions by using cold test and three-dimensional computational fluid dynamics(CFD) simulations.The computational and experimental results indicated that fluid flow maldistribution was significant under various GHSV.Some improvements on distributions could be achieved by changing the location of off-gas outlet.However novel distributors should be developed.Comparison of experimental measurements and simulations showed similar trends.Consequently simulations on concentration distributions in the combustion chamber provided a guidance for further improvement.