Influence of reactions and coefficients on the results

[Łukasz]

Good morning,

I am a Pyrosim user.

I would like to ask what effect the selected combustion reaction with specific carbon, hydrogen, nitrogen and oxygen atoms (I am currently using the SFPE Polyurethane GM 37 reaction) has on the visibility range and temperature if I set the soot factor (Ys) to 0.08 and heat of combustion 3,0E+4 kJ/kg?

Will the change in reaction to SFPE Polyurethane GM 27 affect the visibility range, temperature results if the soot coefficient (Ys) is still set to 0.08 and heat of combustion 3,0E+4 kJ/kg?

Does the change in the value of individual atoms C, H, N, O in the reaction matter if I enter the same coefficient values in both reactions- soot coefficient (Ys) is still set to 0.08 and heat of combustion 3,0E+4 kJ/kg?

In the case of the GM27 reaction, the atoms C, H, N, O have different values. 

In both cases, I mark the reaction type as simple chemistry.

I would like to model a fire in a typical hall with a height of approx. 12.0-14.0 m with high storage racks, where polyurethanes, polyethylene bottles in cartons can be stored.

In addition, I would like to note that the heat of combustion values for the SFPE Polyurethane GM27 and GM37 reactions mentioned in the Pyrosim program are different than those given in table A.38

According to the table in the fifth edition of the SFPE Heandbook, GM27 has a heat of combustion of 23.2 kJ/g and GM37 has a heat of combustion of 28 kJ/g.

Best Regards,

Thank you

[Kevin McGrattan]

If you set the HoC and soot yield and the burning rate of the fuel (HRRPUA, for example), then the chemical composition of the fuel molecule is not important. You are specifying how much energy is released and how much soot is generated.

[Randy McDermott]

With the caveat that the molecular weight is reasonable…

On Sat, May 20, 2023 at 9:42 AM Kevin McGrattan <mcgr...@gmail.com> wrote:

If you set the HoC and soot yield and the burning rate of the fuel (HRRPUA, for example), then the chemical composition of the fuel molecule is not important. You are specifying how much energy is released and how much soot is generated.

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[Łukasz]

Thank you Mr. Kevin

[Łukasz]

Thank you Mr. Randy