Propriedades termofísicas de fluídos secundários à base de álcool para termoacumulação

Abstract

This paper evaluates thermophysical properties of secondary fluids for their application in refrigeration systems with cool thermal storage. The object of research are aqueous solutions with organic antifreeze of alcohols family – glycerol, propylene glycol and ethylene glycol – that have thermophysical properties – melting point and boiling point, density, specific heat, thermal conductivity – different of pure water, which mainly promote reducing of the melting point. The alcohols were selected because they are completely soluble, with low or no corrosion activity and chemically stable. The properties of secondary fluids were obtained with the aid of computer simulation. In all samples, with the mass concentration of solutes ranging between 20% and 50%, were not detected inflection points in curves of the properties when the concentration of the alcohol was varied. The initial investigative hypothesis for freezing point temperature reduction of the solution, with increase in the alcohol percentage, was confirmed for all samples. The ability to transfer heat is reduced to all secondary fluids to the extent that the alcohols concentration is increased. Comparatively, the ethylene glycol showed to be, among alcohols tested, that the one best attends the needs for a secondary fluid, such as antifreeze additive