Ranque-Hilsch vortex tube is a simple mechanical device that has no moving components and is used as part of the equipment in the refrigeration system, where a high pressure fluid is entered the vortex tube through the entrance nozzles and splits into two flows with lower and higher temperature compared to inlet temperature, and in this way temperatures up to -40 °C are achievable. Vortex tube has broad applications as spot cooling and spot heating in the industry such as cool plastic injection moulds, dehumidify gas operations, cool heat seal operations, cooling of control cabinet electrical enclosures, cooling of camera lenses, setting solders and adhesives, and dry ink on labels and bottles. Although many experimental studies have been done on the performance of vortex tube, the physics of the flow and mechanism of temperature separation phenomenon of gas or vapor passing through the vortex tube are not well understood because of complexity of the flow and incompatibility of experimental results. The first goal of this thesis is to record cold and hot temperatures, triggered by temperature separation phenomenon, versus cold fraction experimental investigation of one type of vortex tube-experimental equipment R433 made by P.A.Hilton company in England. Experimental results include cold and hot exit static temperatures diagrams based on cold fraction and cold exit pressure diagram versus cold fraction using cold and hot exit static temperatures. Heat pump and cooler coefficient of performance diagrams of vortex tube, and also isentropic efficiency are presented according to available equations. Uncertainty of experimental results is calculated using experimental Holman relation and is illustrated as error bars in the former diagrams Then using computational fluid dynamics approaches available in ANSYS CFX 14.5 software, numerical simulation of steady, compressible, and three dimensional flow in the vortex tube has been done by utilizing computational, structural and hexahedral grid. Appropriate boundary conditions are applied in the numerical simulation corresponding to the experimental conditions, with the exception of hot exit which has been set such that the operation of flow-control valve could be assimilated. Several turbulence models such as the standard model,, and have been used. Finally hot and cold exit static temperatures, heat pump and cooler coefficient of performance, and isentropic efficiency diagrams derived from numerical simulation have been compared to the ones based on experimental results. In addition, results of numerical simulation are presented as contours of static temperature, stagnation temperature, density, mach number, velocity distributions and stream lines focused on position of stagnation point and the zone which secondary flow forms. Key words : Vortex Tube, Experimental Investigation, Computational Fluid Dynamics, Temperature Separation, Cold Fraction, Standard