Latent and sensible heat transfer in air cooling applications

Purpose - Joint descriptions of both heat and mass transfer and thermodynamic aspects of air-cooling applications cannot be easily found in the literature. Numerical analyses are a notable exception since suitable physical models and realistic boundary conditions are a prerequisite of accurate simulations. Thus, it is believed that the experience gained with numerical simulations might be of some help also to designers of air-conditioning and drying systems. This paper seeks to address this issue. Design/methodology/approach - In the text, the physical implications of governing equations and boundary conditions utilized in numerical simulations are extensively discussed. Particular attention is paid to the thermodynamically consistent definition of latent and sensible heat loads, and to the correct formulation of the heat and mass transfer analogy. Findings - Comparisons of analytical and numerical results concerning forced flows of humid air over a cooled plate validate the assumptions made in numerical simulations, both for air-conditioning applications (almost always characterized by low rates of mass convection) and drying applications (almost always characterized by high rates of mass convection). Originality/value - Finally, with reference to the cold plate problem investigated here, the effects of the suction flow induced by condensation on the Nusselt number are quantified