Forced convection condensation inside minichannels: guidelines for a new predictive procedure

Condensation inside minichannels finds many applications, such as in heatpipes for electronic machinery or for spacecraft thermal control, or in automotive condensers. It has also been suggested for air-conditioning and refrigeration applications, in order to design compact heat exchangers, to reduce refrigerant charge, to use natural refrigerants, to improve cycle efficiency. Because of the influence of flow regimes on heat transfer andp ressure drop, a literature review is presented to discuss flow regimes transitions. The available experimental heat transfercoefficients were already compared by the present authors in previous papers with semiempirical and theoretical models developed for conventional channels and with models specifically developed for minichannels. The assessmentof the results pointed out the need for new design methods. Starting from this standpoint, a new procedure is reported in the present paper which takes into account the effect of the entrainment rate of droplets from the liquid film.