Temperature Measurement of Carbon Dioxide Using Emission Spectroscopy

Abstract

This paper presents a relatively simple method for temperature measurement of hot carbon dioxide gas using an emission spectroscopy setup. The v3 band emission at 4.3 um is detected using an optical bandpass filter and a mercury cadmium telluride detector. A conversion methodology is introduced that calculates the detector voltage from the spectral radiance considering the spectral sensitivities of the optical components and the non-linear characteristics of the detector. Two radiation models, a line-by-line model and a random statistical narrow band model, are employed to calculate the spectral radiance at given flow conditions. Black body radiation is considered for radiance calculation for optically thick conditions. Temperatures under test conditions in a shock tube are determined using the proposed conversion methodology and are compared with the temperatures obtained from a computational fluid dynamics simulation. The accuracy and efficiency of the temperature measurement using the two radiation models and the black body curve are compared. It is confirmed that the proposed method is a reliable way to determine the temperature while using a relatively simple experimental setup. Detector voltages are presented for a wide range of temperature, pressure, and beam path length for applications under different test conditions.