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Title:Cop and capacity improvement through work and heat recovery by using vortex tube
Author(s):Mohiuddin, Muhammad
Advisor(s):Hrnjak, Predrag S.; Elbel, Stefan
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Vortex tube
Heat, ventilation, air conditioning and refrigeration (HVAC&R)
Abstract:The vortex tube is an intriguing device that separates an incoming high-pressure fluid stream into two low-pressure streams. Work interaction during the expansion process causes a temperature decrease in one of the two exit streams, while the other one experiences a temperature increase. The expansion process in a vortex tube therefore approaches isentropic rather than isenthalpic expansion, and the internal flow separation is achieved without any moving parts, resulting in robust and inexpensive designs. Commercially available vortex tubes are almost exclusively used for spot cooling in industrial applications and use compressed air as the working fluid. In addition, vortex tubes have been gaining lots of attention in air-conditioning and refrigeration research, because of the possibility to replace the expansion valve of vapor compression systems with this low-cost device that can recover expansion work that would otherwise be lost in the isenthalpic throttling process. Most of the work on vortex tubes used for refrigeration have been numerical studies, and many of them predict very optimistic energy efficiency improvements. However, the few papers available that describe experimental validation of vortex tubes in HVAC&R systems are far less optimistic, which is often caused by the selection of cycle architectures that seem inappropriate for vortex tubes. This thesis takes a fresh look at performance of commercially available vortex tubes with refrigerant and its possible application in refrigeration. A new experimental facility is developed to assess vortex tube performance on a fundamental level for different working fluids, including air and R134a. Suitable vortex tube operating conditions have been identified and efficiencies have been calculated from experimental results for both air and R134a. Experimental investigations show that the vortex tube using high pressure saturated R134a vapor at inlet can achieve up to 35% isentropic efficiency while creating a temperature difference of 18 C between the two low-pressure outlet streams. Based on these new findings, numerical simulation is carried out to investigate the performance of a novel vortex tube cycle that is able to utilize the demonstrated improvement potentials when applied to vapor compression systems. The cycle utilizes temperature separation capability of vortex tube to achieve higher subcooling at evaporator inlet to increase system COP and reduce refrigerant mass flow rate through the system.
Issue Date:2014-05-30
Rights Information:Copyright 2014 Muhammad Reaz Mohiuddin
Date Available in IDEALS:2014-05-30
Date Deposited:2014-05

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