Pyrolysis of n-Heptane

[GShivam]

Hello,

I am trying to do pyrolysis of n-Heptane. 

In simulation, The HHR is not reaching to the desired  value of 300 kW for pan diameter of 0.46 m. 

Instead it attains the values of around 200 kW. 

I have used the following properties of n-Heptane based on the information on NIST and few paper.

Density = 684 kg/m^3

Specific heat = 2.22 kJ/kg.K

Thermal conductivity = 0.14 W/(m·K)

Emissivity  = 0.9

Absorption coefficient = 0.08 1/m

Boiling Temp = 98.5 °C

Heat of Combustion = 4.817E4 kJ/kg

Heat of Vaporization =317.7 kJ/kg

Grid Size = 0.05 cm

Kindly suggest How to achieve the desired HHR of 300 kW.

Apart from this, i have one more queries.

I am also trying to do simulation using burner. 

I have given auto ignition temperature of 223°C in order to reduce superfluous combustion in the cell.

I have also provided the ramp of HRR.

Due to Auto Ignition temp, the combustion starts at 1.8s when default ramp of 1 sec is used. 

However, As i tried to provide Ramp from my side including using of Auto Ignition Temp 

i observe no combustion of fuel. 

I have provided the below value in ramp.

time    Fraction

1.5      0.0

1.8      0.008

2.0      0.05

8.0      0.6

16.       1.0

Although fraction value = 0.008 at t = 1.5 s was calculated as the value obtained from simulation using default case of ramp (1s).

Kindly provide the some suggestion how to resolve this?

Is it possible to use RAMP function provided that AUTO IGNITION TEMP is on?

or 

Should i remove the AUTO TEMP? (without auto ignition temp simulation runs fine)