UBC Theses and Dissertations
Numerical and experimental study of the performance of bulk-air spray coolers and renewable cooling systems for application in mine ventilation Kuyuk, Ali Fahrettin
Depletion of shallower resources is challenging modern mining industry to reach deeper deposits to maintain global mineral and raw material demand. As mines grow deeper and get more complex, heat loads associated with production, air compression and geology become an important issue for the health and safety of underground workers. For this purpose, mining industry uses water-based bulk-air spray cooling systems. However, design of these systems is reliant on semi-empirical models that were developed based on restricted empirical data collected from limited chamber size and geometry. Therefore, they often fail to respond when the granularity of the operating parameters such as droplet size, air velocity or chamber geometry is challenged by the application. To mitigate this issue, numerical models can be used effectively. Nevertheless, mining literature is missing an extensive study of these cooling chambers with numerical methods. Moreover, mine air conditioning systems are energy intensive, and their energy performance is highly related to their design. To fill this gap, first, the energy problem associated with conventional mine cooling systems were raised and examined with different case studies. These case studies have shown that, there are alternative cooling solutions for deep-mines, and they could offer similar cooling performances with relatively less capital investment. Then, a fully coupled numerical model that can replace conventional design methods was introduced and validated with series of lab experiments. Literature survey done on similar concepts with applicable scales has shown that earlier studies are mainly investigating evaporative cooling of spray cooling systems without offering a relevant condensation criterion to capture the two-way multiphase physics seen in bulk-air cooling applications. In these terms, this study provided a more inclusive approach by introducing a saturation criterion to Lee’s mass transfer model used in multiphase modelling. Finally, once validated with experimentation, the lab-scale solution was scaled up to an industry compliant, full-scale, multistage bulk air cooler model to benchmark the conventional methods. The studies have shown that; numerical models presented here agreed with the experimental work and semi-empirical models within a reasonable error and promised higher granularity when it comes to understanding the system merit and effectiveness.
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