Actively Cooled Calorimeter Measurements and Environment Characterization In a Large Pool Fire

Abstract

Quasi-steady-state heat fluxes absorbed on the calorimeter surface in ten vertical 0.1 m highx 1 m wide zones were measured by means of water calorimetry. The calorimeter surface also included an array of intrinsic thermocouples to measure surface temperatures, and an array of Schmidt-Boelter radiometers for a second, more responsive, method of heat flux measurement. The pool fire environment characterization was done with measurements from velocity probes, directional flame thermometers (DFTs), and thermocouples. The initial measurements with a 1 m x 1 m water cooled vertical flat plate calorimeter located 0.8 m above and inside a 6 m x 6 m JP-4 pool fire are described. Water calorimetry measured absorbed surface heat fluxes of about 65-70 kW m-2 with a gradual decrease with increasing height above the pool. Intrinsic thermocouple measurements recorded typical calorimeter surface temperatures of about W C , with spatial variations of f 150°C. Gas velocities across the calorimeter face averaged 3.4 m s-' with a predominant upward component, but with an off-vertical skew. Analysis of data collected in the fire environment in the vicinity of the calorimeter was performed to characterize the fire environment and to determine the input parameters required to calibrate analytical models. For this test, the emissive power distribution near the plate was essentially linear. Flux measurement in the fire environment ranged from 75 kW m-2 to 175 kW m-2. With temperature and heat flux data, effective absorption coefficients were determined by using a two-flux method to solve the inverse problem. The results show that the optical thickness increases with increasing distance from the calorimeter surface. The effective absorption coefficient is approximately 0.8 m-l in the vicinity (0-1.85 m) of the calorimeter and is approximately 2 m-l in the vicinity (1.85-2.8 m) of the plume centerline. The observed decrease in heat flux on the calorimeter surface with increasing vertical height is consistent with analytical fire models derived for constant temperature surfaces. Results from several diagnostics also indicated trends and provided additional insight into events that occurred during the fire. Some events are correlated, and possible explanations are discussed.

Coupling of Large Fire Phenomenon with Object Geometry and Object Thermal Response

“…Similar trends have been observed in experiments including a large flat plate by Gritzo et al [13] and water-cooled calorimeter by Koski et al. [14]. Reduction in incident heat flux to, and a reduction in temperature near, cold surfaces have consistently been observed.…”

Fire Size of Gasoline Pool Fires

“…The theory developed by Babrauskas [20] is accepted [5,6,[9][10][11]14,21,22] as a basis for assessing the heat release of pool fires. Babrauskas [20] laid the foundations for the calculation of the "fire size" of flammable liquids, if the combustion mode is specified ( Table 1).…”

Experimental and Numerical Investigation of Transient Soot Buildup on a Cylindrical Container Immersed in a Jet Fuel Pool Fire

“…Typically, researchers have used an absorption coefficient value of 1 m À1 (Nicolette and Larson, 1990). According to Koski et al (1996), the average effective soot absorption coefficient ranged from 0.8 to 2.3 m À1 for a JP-4 flame. Longenbaugh (1985) used experimental radiative heat flux measurements inside a sooty pool fire to compute the effective soot absorption coefficient.…”