Negative Q_RADI and Q_CONV values in CHID_hrr.csv file

[Moody Rashid]

Hi,

I am trying to measure RADIATIVE HEAT FLUX and CONVECTIVE HEAT FLUX on a structure. I have run a grassfire simulation in FDS 6.6. I have set a number of devices on the structure. I found that the Q_RADI and Q_CONV columns have large negative (-ve) values in CHID_hrr.csv file. However, in the CHID_devc.csv file all devices have reasonable positive values for both radiative and convective heat fluxes. 

I am seeking help to know - why the values of Q_RADI and Q_CONV are coming negative in CHID_hrr.csv file?

With thanks,

Moody

[dr_jfloyd]

The values in the hrr.csv file are not the same as a heat flux device. Please review the definitions of those quantities in 21.10.1 of the User's Guide. These quantities are all with respect to the gas portion of the domain. Negative Q_RADI means you are losing radiation from the gas.