Application of vortex tubes in an underground mine ventilation system

Thesis (M.S.) University of Alaska Fairbanks, 2021A major challenge for deep underground mines in tropical regions is high-temperature climate conditions at a working face. The high-temperature conditions can cause discomfort to people working underground and lead to health and safety issues. In some instances, airflow from primary ventilation and central refrigeration systems is not adequate to reduce the ambient temperature below a permissible limit at remotely located working faces. In some mines, mobile cooling systems are used in conjunction with an existing central cooling system. However, mining companies are often skeptical about implementing the combined cooling system due to its high operating costs involved with refrigeration infrastructure. This research examines the potential of a low-cost, maintenance-free vortex tube spot cooling system that operates on compressed air and can work with or without a central cooling system. Using an underground metal mine in Ghana as a case study, the impact of a vortex tube cooling system at a working face was evaluated using the computational fluid dynamics (CFD) technique. An integrated CFD model of vortex tube, ventilation duct, and development heading was developed. The airflow was simulated within the CFD model with a varying number of vortex tubes and locations. The simulation result shows that the mine can achieve a decent temperature drop from 28°C (82.4°F) to 24°C (75.2°F) with 20 vortex tubes at the working face.Institute of Northern Engineering, Department of Mining and Mineral EngineeringChapter 1: Introduction -- 1.1. Background and problem statement -- 1.2. Research objectives -- 1.3. Research methods -- 1.4. Organization of thesis. Chapter 2. Overview of vortex tube -- 2.1. Introduction -- 2.2. Overview of underground mining -- 2.3. Mine ventilation -- 2.3.1. Sources of heat in underground mines -- 2.3.2. Heat exposure and heat stress control -- 2.3.3. Heat control strategies -- 2.4. Vortex tube -- 2.4.1. Vortex tube components -- 2.4.2. Vortex tube working principle -- 2.4.3. Classifications and types of vortex tubes -- 2.4.4. Vortex tube performance indices -- 2.5. Commercial applications of vortex tubes -- 2.5.1. Personnel cooling clothing -- 2.5.2. Vortex tube based refrigeration and cooling systems -- 2.5.3. Spot cooling for machining operations -- 2.5.4. Other applications of vortex tubes -- 2.6. Vortex tubes for mining applications -- 2.7. Numerical modeling in mining. Chapter 3: Numerical modeling and simulation -- 3.1. Introduction -- 3.2. Mine model -- 3.3. Vortex tube model -- 3.4. Geometry creation -- 3.5. CFD model -- 3.6. Boundary condition -- 3.7. Mesh independence study -- 3.8. Turbulence model. Chapter 4: Results and discussion -- 4.1. Introduction -- 4.2. Simulation results -- 4.3. Discussion. Chapter 5: Conclusion and future work -- 5.1. Conclusion -- 5.2. Future work -- References -- Appendices