Temperature measurements on solid surfaces in rack-storage fires using IR thermography

摘要

The devebpment of fire modeling took capable of predicting large-scale fire phenomena is of great value to the fire science community. To this end, FM Global has developed an open-source CFD fire simulation code, FireFOAM. The accuracy of this code relies fundamentally on hgh-quality experimental validation data. However, at larger scales, detailed measurements of local quantities (e.g., surface temperatures) needed for model validation are difficult to obtain. Often, the information obtained from large-scale fire tests is limited to the global heat release rates (HRR) or point temperature or heat flux measurements from embedded thermocouples or heat flux gauges, respectively. The present study addresses this limitation by introducing IR thermographic measurements in a three- and a five-tier-high rack storage scenario. IR temperatures are compared against modeled results. The tested and modeled cases represent realistic industrial warehouse fire scenarios. The rack-stored commodity consisted of corrugated paperboani boxes wrapped around a steel cubic liners, placed on top of a haidwood pallet. The global heat release rate was measured using a 20-MW fire products collector located inside FM Qobal's Fire Technology Laboratory. An in-house calibrated microbobmeter IR camera was used to obtain two-dimensional temperature measurements on the fuel surfaces and on the surfaces inside the flue spaces. Maximum temperatures up to 1200 K were observed on the external surfaces of the test array. Inside the flue spaces between pallet loads, temperatures up to 1400 K were measured. The modeled fire spread results match well fire spread shown in the IR thermographic images. The peak modeled surface temperatures obtained inside some of the horizontal flue spaces were -1400K, which agreed well with the peak temperatures seen by the IR camera. The effect of fee flames present between the surfaces of interest and the IR camera only contribute to about 50 K increase in measured temperature due to the limited flame emissive power with low soot concentration in the long-wave IR regime. This study shows the capability of IR cameras to obtain high resolution temperature measurements in large-scale fire scenarios, which enhances existing large-scale model validation data set.