The heat release rates (HRRs) in fire experiments with gaseous fuels in tunnels were generally determined by the product of supplying fuel rates and their heat of combustion with the assumption that gaseous fuels could combust completely irrespective of ventilation conditions. In this paper, systematic calibration of the HRRs of propane fires at varying ventilation conditions in a tunnel was conducted by using the oxygen consumption method. Firstly, the HRRs of propane fires were calibrated in open space and the calibrated values agreed well with the theoretical ones. Then, a series of fire experiments were conducted in a 1:20 reduced-scale tunnel. The supplying fuel rates varied from 2.0 l/min to 27.7 l/min, corresponding to theoretical HRRs of 2.8 kW to 39.1 kW, at ventilation velocities from 0.01 m/s to 2.27 m/s. The results showed that the ventilation velocities have a marked impact on the HRRs of propane gas fires. The HRRs for a flow rate of 11.9 l/min at velocities of 0.74, 0.19 and 0.06 m/s were around 19.4, 15.3 and 5.9 kW respectively. At a velocity of 0.06 m/s, the HRR was around 30% of the HRR in open space. The HRRs increased with velocity at low ventilation velocities and they were independent of ventilation velocity at higher ventilation velocities, An outer envelope of HRRs given by an empirical equation, which represented the achievable maximum HRRs at given velocities, was proposed for propane fires. The applicability of using a fuel-to-air equivalence ratio to represent the status of ventilation conditions for gaseous combustion was discussed.

隧道中气体燃料火灾实验中的热释放率 (HRR) 通常由供应燃料率及其燃烧热的乘积决定，假设气体燃料可以完全燃烧而与通风条件无关。在本文中，使用耗氧量法对隧道内不同通风条件下丙烷火灾的 HRR 进行了系统校准。首先，丙烷火灾的HRRs在开放空间进行了校准，校准值与理论值吻合良好。然后，在一个 1:20 缩小的隧道中进行了一系列火灾实验。供应燃料速率从 2.0 l/min 到 27.7 l/min 不等，对应于 2.8 kW 到 39.1 kW 的理论 HRR，通风速度从 0.01 m/s 到 2.27 m/s。结果表明，通风速度对丙烷气火灾的 HRR 有显着影响。在流速为 0.74、0.19 和 0.06 m/s 时，流速为 11.9 l/min 的 HRR 分别约为 19.4、15.3 和 5.9 kW。在 0.06 m/s 的速度下，HRR 约为开放空间中 HRR 的 30%。HRR 在低通风速度下随速度增加，并且在较高通风速度下与通风速度无关。 由经验方程给出 的 HRR包络被提议用于丙烷火灾，该方程代表在给定速度下可达到的最大 HRR。讨论了使用燃料空气当量比来表示气体燃烧通风条件状态的适用性。