AN INVESTIGATION INTO THE INFLUENCES OF REFRIGERANTS' THERMAL-PHYSICAL PROPERTIES ON TEMPERATURE SEPARATION EFFECT OF A VORTEX TUBE.

The temperature separation effects of vortex tubes have been widely studied in open systems, using mainly air or N2 as the working fluid. When a vortex tube is employed in a closed thermal system, more fluid choices, such as refrigerants, could be considered. Different to air, refrigerants have quite varied thermal-physical properties, and research of the thermal-physical properties' influence on the temperature separation effect is rather limited. Based on CFD simulated temperature separation effect of eight refrigerants (R152a, R290, R134a, R600a, R143a, R245fa, R227ea, and R218), this study attempts to gain a better insight into how their properties could be related to compare their temperature separation performance. The analysis shows for small mass-flow ratios at the cold end, the cooling effect can be assessed by the relative values of their isentropic expansion exponent. The results also suggest that a large thermal diffusivity and kinematic viscosity, and a small vapour density and Joule-Thomson coefficient would lead to better heating effects. [ABSTRACT FROM AUTHOR]