Instrumentation Design for HRR Measurements in a Large-Scale Fire Facility

Carleton University’s experimental atrium and tunnel facilities share a fan chamber and three large exhaust fans. Using oxygen consumption calorimetry, the Heat Release Rates (HRR) of fires in either of these facilities can be calculated. This paper focuses on the design of the instrumentation in the fan chamber, which was carried out using the Fire Dynamics Simulator (FDS) and manual velocity measurements. Due to a high amount of mixing and turbulence and a long travel distance, the temperature and gas concentration profiles are relatively uniform. However, for the same reason, the velocity profile had to be looked at very closely to find an optimum combination of bi-directional probes. The analysis indicated that acceptable HRR measurements can be obtained using an array of six thermocouples, four bi-directional velocity probes and a gas sampling grid. Results from the preliminary tests are presented. The system shows a reasonable estimate of the HRR as compared to the propane calibration burner.