The concept of radiation fire modeling is developed. It allows one to reproduce the behavior of large-scale fires using model-scale fires at elevated pressure. It preserves large-scale fire heat fluxes and hum times by increasing the ambient pressure while maintaining the length-scale pressure-squared product l · P~2, invariant. The paper discusses the full range of modeled and non-modeled quantities. The radiation fire modeling hypothesis is based on two assumptions: (1) the flame heat flux comes primarily from soot radiation, and (2) soot formation in diffusion flames is second order in pressure and is characterized by the fuel smoke point. The radiation and second-order pressure dependence of soot formation in diffusion flames is carefully argued in the paper. The modeling concept was tested and confirmed by a series of model-scale pool-fire experiments performed in Factory Mutual Research's large pressure vessel at pressures up to 2.5 atm. These experiments are compared to pool-fire measurements performed at atmospheric pressure at diameters up to 1.2 m. The square exponent on pressure provides the best fit to the data. These pool-fire experiments, between the optically thin and optically thick limits, were specifically chosen to offer the most severe challenge to the modeling concept.
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