Direct-Contact Heat Transfer Processes

Abstract

A key challenge in the design of efficient energy conversion systems is to achieve effective heat transfer at temperatures that can extract the maximum thermodynamic potential of the system’s heat source. In classical heat exchangers, heat transfer takes place through a wall separating the hot and the cold fluid streams. Thus, conventional heat exchangers are limited in their ability to tap the maximum thermodynamic potential because they have built-in thermal losses associated with the separation of the fluid streams by an intervening solid wall. This type of configuration also leads to a deterioration of the heat transfer effectiveness as the heat transfer coefficients decrease with time due to fouling. In the case of high-temperature applications, thermal stress and corrosion problems are imposed on the wall materials themselves. These situations are present irrespective of whether the two fluid streams are solid, liquid, vapor, gaseous, or some mixtures of them.