ARTICLE:

• ABSORPTION OF REFRIGERANT IN LUBRICANT OIL: A VISUALIZATION STUDY  download article

M. A. Ortolan
Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, Brazil

Jader R. Barbosa
Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, Florianopolis — SC 88040-900 Brazil

ABSTRACT

Experiments were conducted to visualize the flow field during absorption of refrigerant vapour in an initially stagnant layer of lubricant oil. The system under study is Rayleigh (concentration) unstable as vapour absorption takes place through the top interface of the liquid layer and because the density of the pure liquid refrigerant (R-134a) is higher than the density of the oil. The macroscopic motion of the resulting liquid mixture develops shortly after the oil and refrigerant vapour are brought into contact and is associated with natural mass convection in the liquid.
A test rig consisting of a transparent test section through which absorption is observed was specially constructed for the experiments. The flow field was recorded using a video camera. The effects of initial depth of the oil layer (aspect ratio) and refrigerant-oil combination on the velocity field and on the refrigerant absorption rate were assessed. Measurements of system pressure as a function of time during absorption were well correlated with a theoretical model developed by the authors.

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