First of all, Let's us explain about CPHE. This type of heat exchanger is a Cross flow type. Using water and hot gas as its working fluids. Heat exchanger is embedded in porous material that is inside Housing. In this area, porous is very hard and high heat resistant material. Moreover, it is encouraged heat transfer both heat convection and radiation. Then, when the hot gas passes the porous layer, heat transfer between the Hot gas ,Porous material and heat exchanger will occur ,So the gas will condense into liquid.