Investigation of the Transport Phenomena within the Liquid Phase of a Methanol Pool Fire

  • Author / Creator
    Vali, Alireza
  • A 90 mm diameter methanol pool fire was investigated experimentally and analytically. Aiming for well-defined experiments and understanding the physics of the involved transport processes, the liquid-side boundary conditions including the pool’s bottom temperature the wall thermal conductivity and depth were controlled. Bottom temperature was changed from 0ºC to 50ºC, wall material was altered to copper, stainless steel, and quartz, and L was varied to 6, 12, and 18 mm. Burning rate, flame height, liquid and wall temperatures, and liquid velocity fields were measured under steady-state and quiescent environment conditions. The experimental results showed that the burning characteristics of pool fire (burning rate and flame height) were affected by the liquid-side boundary conditions. The temperature profiles along the pool walls also altered from uniform distributions for the copper pool to significantly non-uniform for the quartz pool. The generally observed liquid thermal structure (a uniform-temperature layer above a steep temperature gradient layer) was influenced by the bottom temperature especially when the wall thermal conductivity increased or the pool became shallower. The velocity measurements within the liquid pool revealed the existence of large-scale mixing motions which profoundly contributed to energy transport from the pool wall into the liquid fuel. An energy model was developed to quantify different heat pathways from the flame to the liquid pool and energy changes within the liquid fuel, which predicted the fuel burning rate within ±10% of the measured values. This analysis showed that the heat transfer from the wall to the liquid pool depended strongly on the wall thermal conductivity. The liquid temperature distributions within the pool were also modeled as a constant-temperature region at the top and an exponentially-decreasing-temperature region in the lower part of the liquid pool. It was shown that when the pool became shallower or its bottom became colder, more energy was required for the liquid sensible energy change and less became available for the fuel evaporation. The experimental results and energy models presented in this study suggested that in order to achieve an accurate energy balance for pool fire, the liquid phase phenomena and boundary conditions were important and should be included.

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  • Degree
    Doctor of Philosophy
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