Heat release rate steady burning

Once sustained combustion is achieved, liquid fires quickly reach steady-state burning with a near constant mass-burning rate. As such, the heat release rate for the fire becomes a function of the liquid surface area exposed to air. 

Figure 13 shows representative HRR histories for thermally thick and thin samples of polymers that gasify completely or form a char during burning. It is apparent that none of these heat release rate histories show a constant (steady-state) value of heat release rate over the burning interval as presumed in equation 45. 

A chair burns in a room, releasing 500 kW, and the heat of combustion for the chair is estimated as 20 kJ/g. Fire and room conditions can be considered steady. The air flow rates into a door and through a window are 200 and 100 g/s respectively. Assume the room is adiabatic. The gases have constant and equal specific heats =1.5 kJ/kg K. The ambient air is 25 °C and the chair fuel gasifies at 350 °C. Compute the average temperature of the room gases. Account for all terms and show all work. 

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