Heat transfer analysis of roll-bond evaporator in a small-scale household refrigerator operating with R600a

Abstract

This paper presents the experimental and theoretical assessment of the thermal behaviour of a roll-bond evaporator in a small-scale household refrigerator using the refrigerant R600a as a working fluid. The experimental data were compared with a general correlation employed to evaluate the heat transfer convection (HTC) and radiation of vertical and horizontal plates of the roll-bond evaporator. The evaporator is placed at the top side of the refrigerator. To provide the right boundary state of the evaporator, the refrigerated chamber was taken into consideration. The acquisition data system and experimental setup are described. The local radiation and convective heat transfer coefficient (CHTC) were determined for variation in heating power. In the case of small refrigerated spaces, the heat transfer through radiation cannot be neglected. The CHTC of internal vertical walls is lower than that of exterior walls. The refrigerator is equipped with an electric static heater to provide the corresponding cooling capacity. The steady-state cooling capacity predictions based on refrigerant enthalpy differences and heat source energy equation balancing were 9.66% and 0.88 % higher than manufacturing data. The results achieved a good agreement when the theoretical and experimental data are compared.