AT-90-21-1 -- Design of Evaporators for Liquid Overfeed Systems PDF

This paper presents an evaporator model that accounts for the phenomenon of changing overall heat transfer coefficient and couples the two-phase pressure drop with its associated change in refrigerant saturation temperature to heat transfer. The model is used to suggest optimum overfeed ratios for various refrigerants and conditions. Differences in design criteria between ammonia and R22 are discussed. Effects of parallel flow vs. counterflow circuiting on performance and implied frosting characteristics are examined.

KEYWORDS: designing, evaporators, heat flow, pressure drop, refrigerants, ammonia, R22, performance, refrigeration.