Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Engineering Science

Program

Mechanical and Materials Engineering

Supervisor

Straatman, Anthony G

Abstract

A vortex tube converts a single stream of compressed gas into two outlet streams; one heated, and the other cooled. This phenomenon, referred to as energy separation, is not fully understood, thereby requires further experimentation and analysis. CFD can provide insight, however, such simulations require a complete set of information of the geometric, operational, and performance parameters of particular vortex tube experiments.

An experiment is developed to provide complete information for CFD simulations. The vortex tube under consideration is established by considering reported data from past studies and selecting parameters that yield significant energy separation. An experimental apparatus is developed that can precisely measure the flow properties at the inlet and outlets. In addition to providing operational and performance data for future CFD studies, the experiments conducted showed the magnitude of the energy separation is (at least partially) dependent on the pressure ratio between the inlet and the cold outlet.

Summary for Lay Audience

A vortex tube is a simple device that separates a compressed gas into two flows, one heated and the other cooled compared to the original temperature (referred to as energy separation). The vortex tube has no moving parts and does not use electrical input or chemical reactions to accomplish this energy separation. The process that causes this energy separation between the two outflows is not fully understood, beyond requiring the inlet to be a compressed gas and the flow is rotational. The flow inside a vortex tube is very complex and cannot be accurately measured through experiments, leaving experiments to measure only the flow before entering the vortex tube and after leaving it. The internal flow can be simulated numerically on a computer but requires precise information on the geometry of the vortex tube, and the temperature, pressure and mass flow rate at the inlet and both outlets.

The research conducted in this thesis focuses on; designing a vortex tube that will produce significant energy separation, accurately measuring the inlet and outlet flows, and reporting all information for computer simulation. By designing a vortex tube, it allows for specifying the complete geometry. The mass flow rate is measured before the inlet of the vortex tube, and after both outlets. Sensor blocks containing pressure and temperature sensors are also incorporated into the experimental setup, in between the mass flow measurement and the inlet/outlets. Thus, the geometry of the vortex tube is completely defined, and the temperature, pressure and mass flow rate are known at the inlet and both outlets.

The data collected from the experiments showed that the energy separation is influenced by the pressure ratio between the inlet and the cold outlet. Previously it was thought that increased inlet pressure resulted in an increased energy separation. However, this research shows that it is the increase in the pressure ratio that increased the energy separation. The increased inlet pressure also happens to increase the pressure ratio, similarly to a decreased cold outlet pressure.

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