Process intensification: heat and mass transfer characteristics of liquid films on rotating discs

A novel high intensity heat pump [5] is comprised of a series of discs housed within a hermetically sealed rotating envelope. Each disc is irrigated with a thin film of working fluid as it performs one of the functions (e.g. absorption, evaporation, etc.) within the heat pump cycle. This paper examines the theoretical and experimental performance of these thin films when performing heat and mass transfer to the disc and the surrounding gas, respectively. It is found that very high transfer coefficients can be achieved at modest disc speeds with water-like liquids. However, at higher viscosities, the heat transfer performance is significantly reduced as might be expected. The experimental transfer coefficients are much higher than those predicted by a simple analysis based upon the film or penetration theory. This is attributed to mixing within the film. (C) 1999 Elsevier Science Ltd. All rights reserved.