Flow phenomena inside the Ranque-Hilsch vortex tube: A state-of-the-art review

Energy has become a driving force in the modern world. Much attention is being given to producing electricity from renewable sources to reduce the carbon footprint. However, this is not enough to meet the global energy challenge. Energy efficiency and improved energy usage are equally important to achieve sustainability quickly. Therefore, it is necessary to use devices that can increase energy efficiency and utilization. One such device is the vortex tube, which has significant potential for energy-efficient cooling and separation processes. It also has the advantages of low maintenance and capital costs. This review provides a comprehensive overview of recent work in the field of vortex tubes. Firstly, a general overview of the current status of the research work is presented, which is based on existing review studies. In the next step, the research carried out in the last five years is categorized into the broad categories of computational and experimental work, as well as different subcategories depending on the area of research. This study synthesizes the new findings on some already formulated research areas such as the choice of turbulence model, working fluid, etc. and novel research areas such as geometric modifications and arrangement of vortex tubes. It also provides insightful conclusions and future recommendations for the optimization of vortex tubes. The primary aim of this review is to present the current state of research and identify potential research gaps for future research on vortex tubes. • Ranque-Hilsch vortex tubes have significant potential to enhance energy efficiency. • Numerical work includes fluid choice, turbulence model, and performance optimization. • Experimental domain covers optimization, arrangements, and flow analysis of RHVTs. • More research is required to overcome inadequate efficiency and limited development.