Key
22014
Conference Year
2016
Keywords
R152a, R365mfc, VTPR, vapor pressure, concentration
Abstract
This work presents the vapor pressure and concentration measurement of newly discovered environmentally friendly refrigerants 1, 1-difluoroethane (R152a) and 1,1,1,3,3-Pentafluorbutane (R365mfc), besides their mixture. The experimental procedure used in this work was a VLE recirculation type apparatus in which the liquid phase is circulating around the equilibrium cell. Special attention was given to enable a highly accurate vapor pressure measurement up to maximum pressure of 25 bar. The liquid sampling method was perfected through the use of quick plug valves at the circulation loop of the VLE apparatus. This approach has a great effect in solving the problems of changing the volume of the fluids inside the equilibrium cell, since the sampling unit needs a minimum amount of fluid to be sampled. Moreover a new method for measuring the concentration of this mixture through using a vibrating tube densitometer apparatus (DMA-HPM) has been realized. This apparatus was able to supply data in the temperature range of -10 to 200 °C and pressure of 0 to 1400 bar, with an uncertainty of 0.1%. The experimental data was validated using the Volume Translated Peng Robinson Equation of State and high precision fundamental equations of state by McLinden from National Institute of Standard and Technology (NIST). Other models such as Modified Huron Vidal, Wong Sandler, Lee Kesler and Hoffman Florin have been verified. Amongst all the models, McLinden et.al model achieved vapor pressure deviations of less than 0.073% for R365mfc.The concentration deviations reached -3.1%,-9.8% for a composition of 33.6% R152a and 44.1% R365mfc respectively. The deviations of VTPR and VTPR-MHV2 have led to similar results data in the pure fluids and the mixture respectively.Â