Method for measuring heat fluxes in solid fuel flames using semiconductor sensors

The total and radiant heat fluxes from a flame onto the surface of a solid fuel (polymethylmethacrylate) in the combustion zone for horizontal flame spread over the fuel surface were first quantitatively measured using two water-cooled miniature sensors with dimensions of 2.3 $\times$ 2.3 mm mounted inside the plate. A water cooling design for 2 $\times$ 2 $\times$ 0.5 mm sensors (greenTEG AG) has been developed that makes it possible to place them directly in the combustion zone. Radiant heat flux was measured by a sensor with a protective window made of ZnSe, and the total heat flux was measured by a similar sensor without protective window. The conductive heat flux determined using sensors was compared with that calculated from polymethylmethacrylate flame temperature measurements with thin thermocouples. The maximum radiant and total heat fluxes from the flame to the surface of polymethyl methacrylate measured using thermal sensors were 30–35 and 70–75 kW/m$^2$, respectively.