Simultaneous heat and mass transfer to flat plate in humid air stream under frosting conditions

Abstract

Simultaneous heat and mass transfer from humid air flowing over surfaces at subfreezing temperatures under frosting conditions is a complex process. Investigations have been conducted to study the nature of frost and heat transfer mechanism. However, no satisfactory correlation has been developed so far. This paper reports an experimental investigation carried out for simultaneous heat and mass transfer from humid air to a flat surface under frosting conditions. It has been suggested by some researchers that heat transfer rate can be expressed as the product of mass transfer coefficient with enthalpy potential. The agreement between the experimental values of mass transfer coefficient and those obtained on the basis of heat and mass transfer analogy was poor. The deviation was found as much as upto 100 percent and depended on the enthalpy potential itself, the difference of humidity ratio of air and that corresponding to plate temperature and the air Reynolds numbers. The authors have been successful in developing a correlation which agrees with experimental data to within ± 20 percent.