Flow condensation pressure drop characteristics of zeotropic mixtures of tetrafluoromethane/ethane: Experimental and analytical investigation

Mixed-refrigerant Joule-Thomson (MRJT) refrigeration systems have distinct advantages in the temperature range from 80 to 230 K. Tetrafluoromethane (R14) and ethane (R170) are important components to improve the recuperation process in the middle and low temperature regions of a MRJT refrigeration system. In this paper, an experimental investigation on condensation pressure drop characteristics of R14/R170 mixtures (0.193/0.807, 0.437/0.563, 0.632/0.368 and 0.799/0.201 by mole) in a horizontal smooth tube was carried out. Experiments were implemented at mass fluxes from 100 to 350 kg m⁻² s⁻¹, saturation pressures from 1.5 to 2.5 MPa and heat flux from 8.4 to 44.22 kW m⁻² over the entire range of vapor quality. The different contributions of frictional pressure drop and deceleration pressure drop were calculated and compared. The effects of concentration, mass flux, saturation pressure, heat flux and vapor quality were analyzed and discussed. Finally, a new flow pattern-based pressure drop correlation was developed with a good predictive ability for the present experimental data with a MARD of 8.63%, and 14.20% for the literature data. The model considers the combined effects of the individual pressure drops of liquid and vapor as well as the frictional pressure drop due to the liquid-vapor interaction.