Low-temperature facility for non-contact thermometry at NIS-EGYPT

Abstract

This paper describes the characterization of Stirred liquid bath blackbody.  It relies on the principal method of linking radiation temperature measurements to contact thermometry in low temperature range. It was built in order to improve the uncertainties of the non-contact temperature realization at the National Institute for Standard (NIS) in the temperature range from -30 °C to + 30 °C. Several experiments were carried out in the above mentioned range in order to characterize the system. Characterization comprised studies of its efficiency, temperature stability, uniformity, homogeity, comparison with an infra-red thermometer and the determination of the size-of-source effect (SSE) of radiation thermometer with the direct reading of temperature, which form the majority of radiation thermometers. We present measurements illustrating the magnitude of the effect and the consistency with which such determinations can be made for radiation thermometer. Subtleties that can affect or compound the SSE include variations in the focus or focal point when making such measurements, and the so-called “distance effect” (DE). Also, an algorithm of the Monte Carlo simulation method applied to evaluate the computation of the spectral and total effective emissivity of a specular–diffuse, non-isothermal blackbody cavity formed by a cylindrical tube is described. A thorough analysis was also described representing estimations of contributions for all the sources that affecting measurements.t