Question

compartment fire calculation question

A compartment of dimensions 3 m * 3 m * 3 m has an opening of 2 m * 0.75 m and a fuel load of 700 MJ/m2. Determine the duration of postflashover burning. State and justify any assumptions that you make.

Answer 1

Ans) We know,

Duration of postflashover burning. t = E A / Qv

where, E = Fuel load = 700 MJ/

A = Total floor area = 3 x 3 = 9 sq.m

Qv = Heat release rate

Also, Qv = m Hc

where, m = 0.092

Hc = Heat of combustion of fuel= 16 MJ/kg (assume)

= area of window opening = 2 x 0.75 = 1.5 sq.m

Hv = Height of window opening = 1 m (assumed)

=> m = 0.092 x 1.5 x 1 = 0.138 kg/s

=> Qv = 0.138 x 16 = 2.208 MW

Putting values,

=> t = 700 MJ/ x 9 / 2.208 MW

=> t = 2853 sec or 47.55 min