The impact of duct friction factors and leakage in the design of auxiliary ventilation systems


Dr Dean Millar (Research Chair of Energy in Mining - MIRARCO / Laurentian University), Dr Michelle Levesque (Senior Engineer in Mine/Mill Energy Efficiency - CanmetMINING), Dr Stephen Hardcastle (Managing Director - BBE Consulting Canada)

Opportunities for reducing energy use in auxiliary ventilation systems comprise implementation of measures such as ventilation-on-demand and lower friction ducting. This study shows that leakage from ducts is an important factor that should also be considered for lowering energy use in ventilation systems.Even in well installed auxiliary ventilation systems, leakage occurs at the joints between duct segments. This work will show how leakage affects the operating conditions of auxiliary ventilation systems using a simulation model.Hypothetical case studies were examined using Atkinson friction factor and leakage values derived from field and laboratory tests conducted on plastic and fiberglass ducting. Other cases, obtained from public domain sources which represent a range of friction and leakage conditions, were also examined. The cost of ventilation, represented as the power consumed (kW) for a unit volume of air (m3/s) delivered to the face were examined for each case. The work has shown that leakage has a greater impact than the duct friction factor on the operating costs of auxiliary ventilation systems. This is the case for the range of values included in this study, which are believed to be representative of actual operating conditions.