Oil, Miscibility And Recovery In Vapour Compression Rebrigeration Systems.

A critical review of the literature on various refrigerant/oil mixtures and their effects on system performance has been undertaken. Present methods of dealing with the problems encountered with oil and refrigerant have been studied. An experimental rig has been developed to give information on some of these problems and it consists of a single stage refrigeration system with a suction separator and flooded evaporator, cooling air. The suction separator design enables the refrigerant/oil mixture to be viewed and photographed and samples of the mixture to be removed, A non linear mathematical model giving both transient and steady state responses of the refrigeration system has been derived and has been used to obtain information on the movement of the refrigerant and oil when they are completely miscible with each other. Both the model and experimental apparatus have been used to study the effects of oil on system performance. The interaction between the refrigeration system and its oil recovery system has been studied, using the model. With the aid of the techniques developed, an industrial refrigeration system model has been modified to predict the influence of oil on system performance when the oil is only partially miscible with the refrigerant. An R22/oil mixture was chosen for this study and information on the behaviour of refrigeration systems with this mixture has also been obtained from the experimental apparatus.