Design and calibration of a new compact radiative heat-flux gauge (RHFG) for combustion applications

• A new compact radiative heat-flux gauge (RHFG) for measuring the radiative heat-flux is developed.
• RHFG developed for combustion systems to operate at high temperature (∼1200 K) without any need for water cooling.
• Quartz window is used as separating media of radiative heat flux from mixed environment.
• The RHFG is calibrated under a cone calorimeter with a known radiative heat-flux source.
• Such a gauge is developed which is economical, easily fabricated and assembled.

It is important to develop an inexpensive and robust gauge for measuring the contribution of radiation heat-flux component while operating in high temperature conditions without the need of cooling water supply. This work presents a new compact radiative heat-flux gauge (RHFG) for measuring the radiative heat-flux from combustion systems operating at high operating temperatures (∼1200 K). Various types of total heat-flux meters (convective and radiative) are available for measuring heat-flux. In this study, pure radiative heat-flux measuring gauge (RHFG) is developed. Quartz plate is used as a window of RHFG acting as media to transfer pure radiative heat from the heat source. Copper plate is used as the heat sensing element. A thermocouple is brazed to the copper plate to measure the rate of heat transfer to the sensing element. The mathematical modeling, numerical analysis and construction methodology of RHFG is discussed. Initially, a large sized gauge (G1) is fabricated and calibrated with cone calorimeter. The measured response time of 670 s is observed for G1. Numerical analysis is carried out to optimize the size of RHFG and reduce the response time. Four different gauges with various dimensions (G2, G3, G4 and G5) are analyzed numerically and a response time of 208, 17, 14 and 12 s respectively is observed. The gauge, G5 is manufactured and calibrated with cone calorimeter with known radiative heat-flux and the experimental response time of 13 s is observed. This RHFG is of low cost, simple to manufacture, rugged and requires no water cooling even for high temperature combustion applications.