Pool Fire Definition

[Kumar]

For simulation of diesel pool fire, i have defined a surface using HRR with time RAMP. Also defined REAC material. For Cable fire, adopted same philosophy. The max temp (global max) was 1500 C.

Can there be such high temperature with cable fire ? Am I missing something ?

Thanks in adance.

[Kumar]

I intended to say that, if fire is prescribed by HRR (i.e. energy input to the domain), then temperature rise in domain is same even though materials are different like cable or oil. Rate of rise is different, but in both cases, maximum values are more than 1000 C.

 

I presume that, temperatures in domain may be lesser in case of cable fire than in oil fire. Then shall I avoid using HRR ?

[David Sheppard]

I don't understand the problem. In normal compartment fire scenarios, away from the flame, the maximum gas temperatures in a fully developed compartment fires are typically 800C to 1000C with occasional peaks up to 1200C. This is independent of the fuel type for normal fuels.

[dr_jfloyd]

Does your REAC definition result in a reasonable fuel heat of combustion and heat of combustion per unit oxygen?   

When you say the maximum is 1500 C, is this a layer temperature or is this a point in the flame?

[Kumar]

For Cable Fire in a cabinet, I have defined the materials and REAC in following way:

 

&REAC ID='PVCFIRE'
      FUEL='PVC'
      FYI='C_2 H_3 CL_1'
      C = 2.
      H = 3.
      OTHER = 1.
      MW_OTHER=35.5
      IDEAL =.TRUE.
      X_O2_LL = 0.15
      HEAT_OF_COMBUSTION = 25100.
      MASS_EXTINCTION_COEFFICIENT = 8700.
      VISIBILITY_FACTOR = 8.
      SOOT_YIELD=0.00245   /
&MATL ID='PVC',
      DENSITY = 1360
      SPECIFIC_HEAT = 1.50
      CONDUCTIVITY = 0.1500
      HEAT_OF_COMBUSTION = 25100
      N_REACTIONS = 1
      NU_FUEL = 1.00
      REFERENCE_TEMPERATURE = 250.00
      REFERENCE_RATE = 0.005  /
&SURF ID='CABLE',
      MATL_ID = 'PVC'
      BACKING='EXPOSED'
      HEAT_OF_VAPORIZATION = 333.
      BURN_AWAY=.TRUE.
      THICKNESS = 0.0115  /

 

To start with fire postulation, one of the cable is defined with following HRRPUA. Others are defined with SURF_ID='CABLE'. The total load is around 50 Kg PVC.

 

&SURF ID ='FIRE', HRRPUA=590, RAMP_Q='fireramp' /
&RAMP ID='fireramp', T=  0., F = 0.0 /
&RAMP ID='fireramp', T=  1., F = 1.0 /
&RAMP ID='fireramp', T=  668., F = 1.0 /
&RAMP ID='fireramp', T=  670., F = 0.0 /

 

Following is the domain size and Mesh.

&MESH IJK=184,216,60, XB=-0.10,9.1,0,10.8,0.0,3.0 /

 

The maximum temperature in the compartment (gas layer) is more than 1000 C. With PVC Fire, is that possible ?

 

On Thursday, July 31, 2014 7:48:27 PM UTC+5:30, Kumar wrote:

[Chris]

If you look up the HoC of PVC in the Literature (SFPE-Handbook), than it is not 25.1 MJ/kg. Delta Ht is in the range of 20 and Delta Hch is a factor 2 lower.

[Kumar]

At many locations, the HOC is around 25.1 MJ/kg. However, can the temperature of hot gases shoot to 1000 C ?

Since, the flame tempertures for PVC is less than that.