Performance Study of Finned Tube Evaporators in a Humid Environment

Finned tube evaporators are commonly used as cross flow heat exchangers in air conditioning and refrigeration systems for cooling and dehumidification. A simulation model for the steady-state performance of evaporator coils is developed in this paper. The coils are simulated as equivalent, parallel refrigerant circuits. The governing equations for heat and mass balance across the tube are presented. Local heat and mass balances are applied to a control volume of infinitesimal tube length along the surface of each row for different heat transfer zones, and the uneven distribution of air temperature inside the coils and the local flow characteristics of the refrigerant are simulated. The effects of evaporating temperature, coil face velocity, inlet air temperature and relative humidity on the evaporator performance are presented. The simulation results related to the humid environment with a fixed coil geometry are discussed.