In this work, new thermodynamic models for refrigerant mixtures are provided the binary pairs R-1234yf/134a, R-1234yf/1234ze(E), and R-134a/1234ze(E) based on reference measurements of speed sound, density, bubble-point pressures. Fitting very accurate liquid-phase sound density data reproduces pressures to within close their uncertainty, yielding deviations in less than 0.1% 1% (and R-1234yf/1...

In this study, condensation heat transfer experiments were conducted with two types of plate and shell heat exchangers (P&SHE) using R-134A. An experimental refrigerant loop has been established to measure the condensation heat transfer coefficient of R-134A in a vertical P&SHE. Two vertical counter flow channels were formed in the P&SHE by stacking three plates of geometry with a corrugated tr...

Oil return from the evaporator to the compressor suction port is an important requirement. It is affected by the refrigerant/lubricant properties, gas velocities and piping geometry. The refrigerant R -134a has successfully replaced R-12 in household refrigerators and freezers. This paper describes a test method to estimate the mean oil film thickness and to observe the flow pattern in vertical...

The design of small satellite propulsion systems is often a constant struggle to balance two opposing requirements: system performance and system safety. Cold gas thruster systems utilizing the refrigerant R-134a as a two-phase propellant have the potential to meet both the performance goals and safety requirements. This paper delineates a safety analysis for a general R-134a-based propulsion s...

Tests were run with both R-12 and R-l34a in a water calorimeter. Refrigerant 12 was run with mineral oil as the lubricant. Evaporating and condensing heat transfer coefficients were calculated over a range of temperatures. To evaluate the impact of the lubricant on the heat transfer coefficients, a oil separator was added. Tests were then run with the oil separator over the same temperature ran...

Over the last thirty years, few changes have taken place in reciprocating refrigeration and freezer hermetic· compressors. Of course there have been design improvements and many new applications, but the basics have stayed the same. DOE requirements have brought new energy standards for 1993 and, with most of that work behind them, manufacturers of white goods are concentrating on alternate ref...

Heat transfer coefficient data was taken during in-tube evaporation of five differenct refrigerant mixtures. These measurements were performed in a 318" O.D. (9.7 mm) smooth copper tube at refrigerant temperatures of -zoe and 4°C. Four different mass fluxes ranging from 125 to 375 kg/s-m2 were tested. On a mass basis, the five different mixtures tested were: R-125 (40%) I R-32 (60%), R-32 (30%)...

A series of tests has been completed comparing the system performance of four long term replacements HP62 (44% R~125/ 54% R-143a/ 4% R-134a), AZ-50 (50% R-125/ 50% R-143a), Klea 60 (20% R-32/ 40% R-125/ 40% R-134a), and Klea 61 (1 0% R-32/ 70% R-125/ 20% R-134a) as potential alternatives for the CFC-containing low temperature refrigerant R-502. The tests were carried out under controlled condit...

Refrigerant blends and pure refrigerants have wide applicability in thermal engineering. One of the critical parameters in the design and evaluation of thermal equipment is the heat transfer coefficient, which can be difficult to determine for refrigerants that undergo phase change within the equipment. For pure refrigerants, classical experimental relations developed by Gungor and Winterton (G...