Heat Release Rates in Tunnel Fires

This paper examines the dynamics of heat release rates (HRR) in tunnel fires, highlighting their central role in fire development, spread, and safety management.Drawing on experimental studies, computational fluid dynamics (CFD) modeling, and full-scale incident analyses, it investigates how tunnel geometry, ventilation systems, and fuel sources influence HRR.Particular attention is given to differences between fuel-controlled and ventilation-controlled fires, as well as the transitions between these states during incident progression.The re-search outlines HRR variations across vehicle types, from passenger cars to heavy goods vehicles (HGVs), and quantifies the effects of heat feedback, ventilation efficiency, and combustible surface area on fire intensity.It further discusses HRR's critical impact on tunnel ventilation design, fire suppression sys-tem capacity, and structural resilience against thermal stress and spalling.By synthesizing lessons from road, rail, and metro tunnel scenarios, the study underscores that accurate HRR prediction is essential for optimizing safety strategies, guiding emergency response, and mitigating catastrophic outcomes.The findings reinforce that managing HRR-through integrated engineering, opera-tional planning, and real-time control-is fundamental to safeguarding tunnel infrastructure and human life.