3500 -- A Linear Subgrid Cooling and Dehumidification Coil Model with Emphasis on Mass Transfer PDF

A linear evaporator model has been developed that emphasises the simulation of latent heat flux. The resulting subgrid solutions to the governing equations for simultaneous heat and mass transfer in cooling coils are shown to be a generalisation of conventional cross-flow heat exchanger to account for mass transfer. A comparison was made of the model with measured coil performance obtained from the literature. Average sensible heat flux predicted by the model was within 0.2% of that measured, latent with 2%. The factors most affecting the calculations of latent heat flux were the use of local relationships between refrigerant temperature and heat and mass transfer coefficients and, to a lesser extent, use of the actual Lewis number for a moist air mixture. It was found that the single-pass, cross-flow arrangement of the model was adequate to model the combined cross- and counterflow arrangement common to cooling coils. Linearisation of the air process path and the single-pass refrigerant flow assumption dramatically improved the computational efficiency of the model without sacrificing accuracy.

KEYWORDS: calculating, cooling, dehumidifying, dehumidifiers, heat flow, evaporators, cooler batteries, cross flow heat exchangers, comparing, performance, refrigerants, accuracy, temperature