Crown incident radiant heat flux measurements performed during both firing and non-firing cycles are reported, for the first time, in the combustion space of a regenerative, side-port, 455 metric ton/day, gas-fired, flat-glass furnace. Measurements were acquired through six crown access holes along the furnace axial centerline. Video and visual observations of the glass surface were also made through access ports in the furnace. A three-dimensional numerical model of the turbulent mixing, reaction, and heat transfer processes is also used to predict radiant heat flux to the crown. The measured crown incident radiant heat flux profile during firing cycles rises from 425 kW/m(2) close to the batch feeder to a peak of 710 kW/m(2) near the center of the combustion space, followed by a drop to approximately 575 kW/m(2) near the furnace working end. Numerical model results are in relatively good agreement with measured results. During non-firing reversal cycles, measured flux levels at the crown rise from 320 kW/m(2) near the batch feeder, to a maximum of 565 kW/m(2) closest to the spring zone. Increases in crown incident radiant heat flux due to combustion are quantified, with nominal increases of 105 kW/m(2) in regions closest to the batch feeder and approximately 155 kW/m(2) in the center of the combustion space. Lower increases from combustion (85 and 12 kW/m(2)) are exhibited in locations closest to the furnace working end, During the 20-25 s non-firing reversal period, the incident heat flux to the crown typically decreased between 20 and 50 kW/m(2) at each measured location. Variation of heat flux to the crown during 15-min firing cycles is typically 3-6% of the total incident heat flux, with a maximum typically occurring one-third of the way into the cycle (5-6 min) and declining during the remaining two-thirds of the period. (C) 2001 Elsevier Science Inc. All rights reserved. [References: 42]
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