Thermal Optimization Analysis and Performance Enhancement of Sequential Bundle of Vortex Tubes for Drilling Engineering Cooling Process

Abstract

The vortex tube is a mechanical device with no moving parts that can separate a compressed gas into a hot and a cold stream. Pressurized gas is injected tangentially into a swirl chamber and accelerated to a high rate of rotation. This gas motion creates a cold core and a hot shell. In certain engineering applications such as gas drilling, the use of a high flow-rate air with high pressure and low temperature can improve process efficiency. In these applications, demand for the cold air stream as high as 40 kg/s is not uncommon. In this paper, the use of a vortex tube bundle for generating this large flow-rate of the cold air stream is proposed and evaluated, using numerical simulations. A single commercially available vortex tube can only produce a cold air stream up to 0.008 kg/s. Thus, it will take 5000 such vortex tubes to reach the required flow rate of 40 kg/s. Space limitation, as well as assembly difficulty, makes such an approach unrealistic. The objective of this work is to design a custom-made vortex tube so that a minimum number of such tubes can be used to meet the performance requirement posted by these applications. In this study, computational fluid dynamics (CFD) is used to analyze the flow field, temperature field, and pressure field, and to optimize the vortex tube parameters so that a specific set of desired output can be achieved to meet the application requirements.