A radiation and convection fluxmeter for high temperature applications

Heat flux is an essential parameter for the diagnostic of thermal systems. In high temperature industrial environment, there are difficulties in measu ring incident radiation heat flux as well as in differentiating between the convective and radiative components of heat flux on the heat transfer surf ace. A new method for heat flux measurement is being developed using a poro us sensing element. The gas stream flowing through the porous element is us ed to measure the heat received by the sensor surface exposed to the hot ga s environment. A numerical model of sensor with appropriate boundary condit ion has been developed in order to perform analysis of possible options reg arding its design. The analysis includes: geometry of element, physical par ameters of gas and solid and gas flow rate through the porous element. For the optimal selection of parameters, an experimental set-up was designed, i ncluding the sensor element with respective cooling and monitoring systems and a high temperature radiation source. The experimental set-up was used t o obtain calibration curves for a number of sensors. The linear dependency of the heat flux and respective temperature difference of the gas were veri fied. The accuracy analysis of the sensor reading has proved high linearity of the calibration curve and accuracy of +/-5%. (C) 2000 Elsevier Science Inc. All rights reserved.