Pool fire release rate

It is assumed that the target surface faces toward the radiation source so that it receives the maximum incident flux. The rate of combustion depends on the release. For a pool fire of a fuel with a boiling point above the ambient temperature (Tg), the combustion rate can be estimated by the empirical relation ... 

Duiser (1989) calculates emissive power from rate of combustion and released heat. As a conservative estimate, he uses a radiation fraction (/) of 0.35. He proposed the following equation for calculating the emissive power of a pool fire ... 

Mathematical estimates are available that can calculate the flame and heat effects (i.e., size, rate and duration) for pool, jet and flash hydrocarbon fires. These estimates are based on the "assumed" parameter of the material release rate. To some extent, the ambient wind speed also has a varying influence. 

Figure 5.6. Evaluation Process for Pool Fire 5,8,1, Release Rate...

Release rate is required to determine the size of the pool and fire duration. The release rate can be calculated from other CCPS books such as Guidelines for Consequence Analysis of Chemical Releases (CCPS, 1999), or can be defined as small, medium, or large as shown in Table 5-1. 

Beyond 1150 s in Fignre 11.1, a deep PP melt layer had accnmulated at the surface and was bnming as a boiling liqnid pool fire with the heat release rate... 

In Table 11.9, the heat release rates from minivan parts made of PP and PE, which burned as liquid pool fires in the tests, are in the range of 1004-1341 kW/m. This range is in the lower end of the 1500-2000-kW/m range predicted before for the... 

Data in Table 11.10 from the Cone Calorimeter indicate that the burning behaviors of polymers are similar to those indicated by the data in Table 11.9 from the Fire Propagation Apparatus. Ordinary polymers (which are thermoplastics and melt easily) have very high heat release rates in the range predicted for the liquid pool fires. For example, for the boiling liquid pool fires of PE, PP, nylon 6, and ABS, 2di values at 50 kW/m are in the range of 1133-1304 kW/m from the Cone Calorimeter (Table 11.10) and 1004-1341 kW/m from the Fire Propagation Apparatus (Table 11.9). 

Two approaches are available for estimating the surface emitted power the point source and solid plume radiation models. The point source is based on the total combustion energy release rate while the solid plume radiation model uses measured thermal fluxes from pool fires of various materials (compiled in TNO, 1979). Both these methods include smoke absorption of radiated energy (that process converts radiation into convection). Typical measured surface emitted fluxes from pool fires arc given by Raj (1977), Mudan (1984), and Considine (1984). LPG and LNG fires radiate up to 250 kW/m (79,000 Btu/hr-ft ). Upper values for other hydrocarbon pool fires lie in the range 110-170 kW/m (35,000-54,000 Btu/hr- ), but smoke obscuration often reduces this to 20-60 kW/m ( 6300-19,000 Btu/hr-ft ). 

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