Emissivity Correction for the Wall Temperatures Measured by Infrared Radiation Thermometers in a Hot Tunnel, Kurobe

Abstract

A measurement was operated on 26 November 1978 for the wall temperature of the Jobu railway tunnel which is known as a hot tunnel penetrating the Kurobe Sennindani hot dry rock in the central Japan, by means of infrared radiation thermometers. Correction of the measured temperature is carried out for emissivity of the tunnel wall of rough granite surface, by solving the linear simultaneous equations. Signifi cant correction (6.2°C of its maximum) is due to large variation and irregular distribution of the temperature on the wall surface. Comparison of the corrected temperature with the thermistor thermometer-measuring temperature in the winter of 1975-76 is discussed. It was shown that the infrared radiation thermometer got an advantage over the thermistor thermometer in such severe condition of 41.5°C of the maximum air temperature and 88 to 97 % of relative humidity in the tunnel, because of its faster measurement of 6 hours than that of the latter of 19 days.