Propane and difluoromethane heat transfer coefficient and pressure drop

Resumen

The use of micro- and mini-channels multiport tubes in heat exchangers has become widespread in recent decades, partly due to their being very commonly used in air conditioning equipment. They increase efficiency and compactness of heat exchangers while reducing refrigerant charge. Minimising charge is decisive in present day refrigeration systems and heat pumps because of the great impact of HCFC and HFC refrigerants on the direct greenhouse effect. For safety reasons, this reduction is also crucial in natural refrigerants, like hydrocarbons and ammonia (Poggi et al [1]). One way to achieve these goals is to use compact heat exchangers with mini-channels. There are many international researchers working in this field, such as Del Col [2], Garimella et al.[3] and Park et al [4].The authors of the present study, aware of this, have been working on the subject for some years, (A. López-Belchí et al.[5]). Condensers utilising mini/micro-channels are especially suited for applications demanding high heat dissipation in a limited volume because as the tube diameter decreases, the ratio of area to volume increases, enhancing the heat transfer. The main goal of this study is to characterize two-phase pressure drop and heat transfer coefficient (HTC) inside mini-channels during condensation and the comparison of experimental measurements of propane (R290) and difluoromethane (R32).