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Calculations of the Heat Release Rate by Oxygen Consumption for Various Applications.


pdf icon Calculations of the Heat Release Rate by Oxygen Consumption for Various Applications. (22769 K)
Parker, W. J.

NBSIR 81-2427-1; 41 p. March 1982.

Journal of Fire Sciences, Vol. 2, No. 5, 380-395, September/October 1984.

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Keywords:

calorimeters; fire tests; heat release rate; oxygen consumption; room fires; tunnel tests; oxygen analyzers; oxygen concentration

Abstract:

The oxygen consumption technique is emerging as a powerful tool for determing the heat release rate in a number of diverse fire test applications, including room fire tests, fire endurance tests, the ASTM E 84 tunnel test, and vaious heat release rate calorimeters. Depending upon the constraints of the test, the accuracy required, the availability of instrumentation and computational facilities, and the willingness to put up with experimental inconveniences, a number of instrumentation options have been considered--each of which require different calculational procedures. The purpose of this report is to develop the equations in a general way and show how to adapt them to various applications such as: closed systems versus open systems; trapping carbon dioxide before it reaches the oxygen analyzer, measuring it, or assuming that it is equal to the reduction in oxygen concentration; ignoring carbon monoxide or measuring it; accounting for the density of the exhaust gases or assuming that it is the same as for air; using a high temperature oxygen cell which measures the oxygen concentration in the exhaust duct directly or a paramagnetic analyzer for which corrections must be made for eater vapor trapping; taking into account or ignoring the ambient concentration of water vapor and carbon dioxide; and, improving the accuracy for open systems by monitoring the water vapor in the exhaust duct. The equation developed here should be useful to anyone setting up a new system and will provide a means of calculating the errors which might be expected when simplified procedures are used.