Experimental investigation of capillary tube flow characteristics using refrigerant R600a

The importance of global warning and ozone depletion caused by refrigerants is definitelybrought up by scientific investigations in the last decade. For a future on a healthy world,international commissions concentrate on research activities for replacement of CFC and HFCtype refrigerants with kinds of nature friendly refrigerants. Afterwards, tendency of usinghydrocarbon (HC) type refrigerants get importance in that field. Beyond the environmentalsensitivities, thermodynamical efficiency and product costs are considered in order to selectalternative refrigerants. Intensive comparisons denotes, hydrocarbon type refrigerant R600a(isobutane) can take the place of conventional refrigerants in all aspects adequately.Redesign of refrigeration cycle components, ensuring desired mechanical and thermalcharacteristic properties, is vital. In this way this study aims to investigate the flowcharacteristics of a refrigeration depressurization component, capillary tube, in refrigerationcircuits using R600a. The capillary tubes phase change and fluid flow characteristics, whichare really complex unlike its simplicity, are designated experimentally related to itsdimensional and cycling properties. The mass flow rate through different capillary tubes wasmeasured for various condensing temperatures and degrees of subcooling at the inlet of eachcapillary tube.The variables affecting refrigerant mass flow rate are defined as dimensionless parameters byusing Buckingham π theorem. Moreover, between the defined dimensionless parameters, anempirical correlation was developed with using little squares lineer regression algorithm.Keywords: capillary tube, refrigeration system, condensation, evaporation, subcooling,experimental study, regression analysis, correlation.x