On the cooling of a 360� video camera to observe fire dynamics in situ

Abstract

An analysis was performed to provide design guidance on the cooling of an NIST-developed in situ fire visualization device, called Burn Observation Bubble (BOB). The analysis was to address the question of how long the device can operate in a fire without being damaged by the fire. The analysis included consideration of single-pass and recirculating cooling systems. The resulting design equations depend on the fire scenario, the cooling water flow rate, and the volume ratio of the device volume to recirculating cooling water reservoir. In the limit of an infinite recirculating cooling water reservoir, the design equations reduce to those of a single-pass system. Sample calculations were given to illustrate the applicability of the equations.

On the development of a transparent enclosure for 360° video cameras to observe severe fires in situ

“…While Eqns. (1) and ( 2) are often sufficient for design, more detailed heat transfer calculations were performed by Yang [19]. Yang's dimensionless solutions based on the energy balance of a closed, recirculating system with a heated enclosure and a cooling reservoir incorporate time-dependent temperature change of the reservoir and enclosure, as well as the volume ratio of the two bodies.…”

“…This yields a required water mass of 57 kg (57 liters). More detailed heat transfer analysis that includes the time-dependent increase in reservoir temperature using the equations by Yang [19] show a slightly shorter time of 7 min will result in the 20 °C threshold being exceeded under the assumed conditions. Heat transfer to the water through the threaded pipe was neglected because it was planned to wrap the pipe in thermal ceramic fiber blanket.…”