THERMAL PERFORMANCE EVALUATION OF ROOM AIR CONDITIONERS EVAPORATORS

Abstract

This work presents a thermal performance evaluation of a fin-and-tube evaporator - that is
widely used in packaged air conditioning equipment - using a balanced calorimeter
developed to simulate similar running conditions. The calorimeter determines the heat
rate absorbed by the evaporator, providing qualitative analysis of performance for a given
geometry. The calorimeter inside air is dried out due to the condensation process on the
evaporator under test during the transient period. By this way it is possible to preview the
humidity of the calorimeter domain and its influence with the instrumentation measurement.
The heat transfer rate absorbed by the evaporator is obtained by a lumped approach using
the energy conservation that is applied to the calorimeter domain, and is taken on the
boundaries of the equipment. Physical parameters such as overall heat transfer coefficient
for several types of fins can then be predicted in order to provide information for improving
the energy-efficiency-oriented design. The uncertainties are estimated by the propagation
of relative effects. Uncertainties are evaluated taking into account the systematic effects.
Results are shown in terms of evaporator overall heat transfer coefficient and heat transfer
rate as a function of inlet air temperature.