Calibration of the plate thermometer for measuring heat flux using a conical heater

Abstract

An experimental study was conducted on the calibration method and measurement error for a plate thermometer (PT) that can replace the heat flux gauge (HFG), which is generally used to measure heat flux. A conical heater included in the cone calorimeter (ISO 5660-1) was used. It is well known that this device can easily control heat flux and has excellent measurement reproducibility. Heat flux values between 10 and 50 kW/m2 were considered and the heat flux calculated by PT was compared with the measurement result obtained using HFG. The major finding is that the gas temperature (Tg) required for the calculation of heat flux using the PT must be measured at the bottom of the sample and not in the vicinity of PT’s surface. This resulted in a significantly reduced relative error of approximately 5.3 % based on HFG. It was also confirmed that the conduction correction factor (Kcond), which has the largest uncertainty in the calculation of the heat flux based on PT, was 8.6 W/m2·K on average and the final relative error was significantly reduced to 1.4 % based on HFG. It is expected that the measurement error of the PT can be further improved by utilizing more specific heat flux range settings in the calibration process of the PT using a conical heater included in the cone calorimeter (ISO 5660-1).