Volume 5: Innovative Solutions for Energy Transitions: Part IV

Numerical Study of Heat Transfer and Fluid Flow in Large-Scale Spray Cooling Systems; Example of Mine-Bulk-Air Cooler Ali Fahrettin Kuyuk, Seyed Ali Ghoreishi-Madiseh, Agus P. Sasmito

Abstract

Depletion of shallow mineral resources is forcing mining companies to exploit deeper deposits and design more complex mine access tunnels due to sophisticated nature of subsurface mining. Inevitably, this brings more complex mine ventilation networks, associated with higher energy profiles. Also, deep mines (i.e. deeper than 1km) and ultra-deep mines (i.e. deeper than 2.5km) are subjected to other heat loads, sourced by strata heat, auto-compression and equipment heat. These extreme heat loads result in further energy demands for the purpose of mine ventilation and air conditioning which is usually satisfied by grid power (or diesel generation in off-grid applications). Therefore, understanding the performance of mine ventilation and air conditioning systems is a necessity. For mine ambient air conditioning applications, bulk-air-coolers relying on spray cooling systems are commonly used. Although mine ventilation literature provides enough empirical design tools for industrial bulk-air-cooler system design, it still lacks a deeper numerical understanding to attain higher precisions in large-scale designs. Accordingly, this paper aims to provide a valid Computational Fluid Dynamics and Heat Transfer model to better understand the working principles of bulk-air-cooling systems. For this purpose, a previously validated CFDHT model was used to test the applicability of literature-ready, analytically expressed semi-empirical bulk-air-cooler design tools. Present study not only highlights the robustness of the introduced semi-empirical model, but also shows that the design tools used for modern bulk-air-cooler design purposes can capture an experimentally validated CFDHT model within ~7% agreement.

Keywords advanced mine energy systems, bulk-air-coolers, deep-mine cooling, spray cooling systems, heat transfer, mine ventilation