Durable Heat Flux Sensor for Extreme Temperature and Heat Flux Environments

This paper reports on the development and evaluation of a novel heat flux sensor, the high-temperature heat flux sensor, tested at temperatures and heat flux levels in excess of 1000°C and 10-13 W/cm 2 , respectively. The current sensor configuration uses type-K thermocouple materials in a durable welded thermopile arrangement contained within a surface-mountable high-temperature housing. The steady-state sensitivity of the design is predicted using a simplified one-dimensional thermal-resistance model. The design performance of a prototype sensor is validated using both conduction and convection heat transfer calibration at low temperature. The average experimental values of the sensitivity are 623 ± 33 mV/W/cm 2 and 579 ± 29 mV/W/cm 2 in conduction and convection, respectively. These calibration results compare very well with the predicted room-temperature sensitivity of 559 μV/W/cm 2 . Minimal dependence on heat transfer coefficient is found in convection. Prolonged thermal cycling of the sensor using a high-temperature kiln and a propane torch apparatus demonstrates survivability near the maximum temperature of the thermoelectric materials with negligible oxidation or loss of calibration.