Temperature measurement of particulate surfaces

Abstract

A device has been developed for measuring the surface temperature of particles of 250 μm diameter at temperatures in excess of 300°C. The basic component of the instrument is a liquid-nitrogen cooled indium antimonide cell used in conjunction with a mechanical chopper and signal amplifier. A system of two-colour pyrometry is employed in which two narrow bandpass filters, centred on the 3·1 and 4·5 μm wavelengths are alternately interposed in the beam of radiation from the source at a frequency of 100 Hz. The device has been developed especially for determining the surface temperature of captive fuel particles, but has been used in other applications, notably the temperature measurement of heat exchanger surfaces, where its high sensitivity and non-contact mode of operation have proved particularly advantageous.