TY  - EJOU
AU  - Hernández-López, M. I. 
AU  - Macias-Melo, E. V. 
AU  - Demesa-López, F. N. 
AU  - Serrano-Arellano, J. 

TI  - Transient Numerical Analysis of Carbon Monoxide Dispersion in Underground Spaces under Different Ventilation Conditions: A Localized Fire Scenario
T2  - Frontiers in Heat and Mass Transfer

PY  - 2026
VL  - 24
IS  - 2
SN  - 2151-8629

AB  - The accumulation of carbon monoxide <mml:math id="mml-ieqn-1"><mml:mrow><mml:mo>(</mml:mo><mml:mi>C</mml:mi><mml:mi>O</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math> in underground spaces poses a significant health hazard; therefore, effective ventilation is essential. This study presents a transient numerical analysis under turbulent flow conditions to evaluate <i>CO</i> dispersion, and identify optimal ventilation configurations. Both during normal operation and in scenarios with high localized concentrations, such as a fire event. The governing equations were solved using the finite volume method with the standard k–ε. Turbulence model. Three configurations were analyzed by varying the outlet location: Case A with an upper-left outlet, Case B with a mid-left outlet, and Case C with a lower-left outlet. The Reynolds number (<i>Re</i>) ranged from 500 to 10,000 to represent different flow velocities. The results showed that the time required to purge the interior region ranged from 11 to 16 s for <mml:math id="mml-ieqn-2"><mml:mi>R</mml:mi><mml:mi>e</mml:mi><mml:mo>=</mml:mo><mml:mn>5000</mml:mn></mml:math> and <mml:math id="mml-ieqn-3"><mml:mi>R</mml:mi><mml:mi>e</mml:mi><mml:mo>=</mml:mo><mml:mn>10</mml:mn><mml:mo>,</mml:mo><mml:mspace width="negativethinmathspace"/><mml:mn>000</mml:mn></mml:math>, achieving minimum average <mml:math id="mml-ieqn-4"><mml:mrow><mml:mo>(</mml:mo><mml:mi>C</mml:mi><mml:mi>O</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math> concentrations of 1 ppm. Case C exhibited cross-ventilation that enhanced contaminant removal, whereas Case A demonstrated the highest overall distribution efficiency <mml:math id="mml-ieqn-5"><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi mathvariant="bold-italic">ε</mml:mi><mml:mrow><mml:mi mathvariant="bold-italic">C</mml:mi></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mn>14.364</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:math>. In the localized fire scenario, cross-ventilation minimized <i>CO</i> propagation into the interior, with removal times ranging from 11 to 191 s. This depended on the fire location and the Reynolds number. This study demonstrates that outlet positioning, flow velocity, and the presence of thermal plumes significantly influence <i>CO</i> dispersion and removal. The findings provide practical design and operational guidelines for ventilation systems in confined underground environments, ensuring occupant safety and maintaining indoor air quality during both normal and emergency conditions.
KW  - Numerical simulation; cross ventilation; carbon monoxide dispersion; localized fire; transient analysis

DO  - 10.32604/fhmt.2026.076455