THERMAL COMFORT USING RANQUE-HILSCH VORTEX TUBE

Abstract

Thermal comfort is a situation of mind that express satisfaction with ambient condition. It mainly includes following processes: heating. ventilation and cooling. Different parameters that affect the condition of thermal comfort are air temperature, metabolic rate, humidity and wind velocity. In this experimental work we achieved thermal comfort with the help of Ranque- Hilsch vortex tube. Vortex tube is a self-temperature separating device. It consists of a nozzle, vortex length. orifice and control valve. It can be used as refrigeration machine. Air at high pressure enters the vortex tube and splits in to two parts: one at lower temperature and other one at higher temperature with respect to inlet temperature. We get low temperature due to expansion of air near the inlet nozzle. and high temperature at hot end due to compression of air. Temperature separation is also occurred due to shear between fluid layer, momentum transfer and high swirl speed. But exact explanation for getting temperature separation in vortex tube is still unclear. Vortex tube can be utilized in oil and gas exploration industry, recovering waste energy, low temperature application and - predominantly for cooling purposes. To study the effect of change in thenmo-physical properties such as pressure, temperature, mass flow rate on temperature separation, an experimental setup is developed. It is consisting of a pressure regulator, some fittings, and two pressure transducers, two rotameters, two humidity sensors and few T-type of thermocouples. In this report, the variation of cold and hot temperature drop and humidity at cold exit with different inlet pressures and cold mass fractions. From experimental result we found cold temperature decreases as cold mass fraction increases tip to 0.5, 0.6 and then it increases for low pressure. At high pressure cold temperature decreases up to 0.3 —0.4 and then increases. Hot temperature increases with cold mass fraction as well as with pressure. Relative humidity at exit of cold fluid decreases with the cold mass fraction. But at low pressure, there is very minute changes in humidity. 1-lumidity at high pressure increases at cold side, then decrease as cold mass fraction increases. COP and cooling efficiency have been calculated for different cold mass fraction and pressure. Cooling efficiency first increase with increase in cold mass fraction and later decreases.

Flow inside vortex tube is turbulent and hence the variation of parameters with the Reynolds number should be instigated. Reynolds number at inlet increases with the pressure. Nondimensional cold temperature drop increases, and non-dimensional hot temperature drop decreases with the Reynolds number. We have also found that non-dimensional cold temperature drop first increases with the cold mass fraction up to 0.25 to 0.35, later it decreases. Non-dimensional hot temperature drop decrease with the cold mass fraction.