Numerical analysis of no-frost domestic refrigerator evaporators

Abstract

The air-to-refrigerant evaporator placed in no-frost refrigerators is a critical component because of its simultaneous treatment of both cooler and freezer air streams, which implies a strong drying process on the cooler air flow, and the corresponding intense and non-uniform frost formation process. This paper presents a numerical model developed to analyse fin-and-tube heat exchangers in general and this kind of evaporators in particular. This is a distributed model which gives a very detailed picture of the nonuniform heat exchanger behaviour in terms of heat and mass transfer, considering local effects (frost formation, fin density, in-flow state, etc.). The mathematical formulation and the numerical methodology are presented, showing the model capabilities and level of analysis. Afterwards, illustrative computational results show the potential of the model as a design tool for this application. Validation studies are included in an accompanying paper.