Heat Transfer from Flame Impingement Normal to a Plane Surface

Impinging flame jets have been widely studied
because of their importance in a range of
applications such as materials processing and fire
safety. The purpose here was to determine the
importance of radiation, convection, and
thermochemical heat release (TCHR) under a range of
conditions. Natural gas was premixed with oxidants
ranging from air to pure oxygen in a round burner
that produced uniform exit conditions. Flames
impinged perpendicular to a water-cooled flat disk
segmented into 6 concentric calorimeteric sections
to measure radial heat flux distribution.
Many parameters were varied such as firing rate,
burner-to-disk spacing, oxidant composition and
disk surface treatment. Untreated, polished,
blackened, alumina-coated and platinum-coated disk
surfaces made of stainless steel, copper or brass
were tested. High (blackened) vs. low (polished)
emissivity surfaces showed nonluminous gaseous
radiation was less than 10% of the total heat flux.
Noncatalytic (alumina) vs. catalytic (platimum)
surfaces showed that TCHR was only important for
high O2 oxidants. The radial location of the highest
heat flux depended on oxidant composition.

Autorentext

Charles E. Baukal, Jr. has a PhD from the Univ. of Penna. and nearly 30 years experience in industrial combustion. He has authored or edited 6 books on industrial combustion, authored over 100 technical papers, and has 11 US patents. He is a licensed PE, a Qualified Environmental Professional, and a Board Certified Environmental Engineer.

Klappentext

Impinging flame jets have been widely studied because of their importance in a range of applications such as materials processing and fire safety. The purpose here was to determine the importance of radiation, convection, and thermochemical heat release (TCHR) under a range of conditions. Natural gas was premixed with oxidants ranging from air to pure oxygen in a round burner that produced uniform exit conditions. Flames impinged perpendicular to a water-cooled flat disk segmented into 6 concentric calorimeteric sections to measure radial heat flux distribution. Many parameters were varied such as firing rate, burner-to-disk spacing, oxidant composition and disk surface treatment. Untreated, polished, blackened, alumina-coated and platinum-coated disk surfaces made of stainless steel, copper or brass were tested. High (blackened) vs. low (polished) emissivity surfaces showed nonluminous gaseous radiation was less than 10% of the total heat flux. Noncatalytic (alumina) vs. catalytic (platimum) surfaces showed that TCHR was only important for high O2 oxidants. The radial location of the highest heat flux depended on oxidant composition.