Pyrometry thermal radiation

The majority of pulse calorimetric measurements use pyrometry, which is non-contact (optical) measurement of the thermal radiation emitted fi om any heated body or substance according to Planck s radiation law for black body radiation. Planck s law describes the spectral distribution of black body radiance which provides the basis for the International Temperature Scale (ITS-90) [76], especially above the freezing point of silver [77]. Because Planck s law is only... 

A pyrometer is a non-contacting temperature measurement instrument that is usually used for temperatures above 500 °C, although with some modifications it can measure temperatures below room temperature. The word pyrometry comes from the Greek words pyro (Are) and meter (measure). The basic principle relies on the notion that all bodies emit thermal radiation proportional to their temperature. Pyrometers detect this thermal radiation and through Planck s law the temperature can be determined. 

The transport of thermal energy can be broken down into one or more of three mechanisms conduction--heat transfer via atomic vibrations in solids or kinetic interaction amongst atoms in gases1 convection - - heat rapidly removed from a surface by a mobile fluid or gas and radiation—heat transferred through a vacuum by electromagnetic waves. The discussion will begin with brief explanations of each. These concepts are important background in the optical measurement of temperature (optical pyrometry) and in experimental measurement of the thermally conductive behavior of materials. 

Soot samples were obtained by use of a nitrogen-quench, porous-walled probe and Nucleopore filters (7). Gas phase hydrocarbons were collected by the porous probe as batch samples and analyzed by standard FID gas chromatography. Thermal measurements included gas temperature by radiation-corrected bare wire thermocouple, and soot temperature by Kurlbaum reversal (9, 10) and two color pyrometry (11). 

Temperature is undeniably the most important property for all calorimetric measurements, because it is the common denominator. Two different techniques for temperature measurements are used for pulse calorimetry contact thermometry (e.g. thermocouples) and radiation thermometry or pyrometry. Because pulse calorimetry is often used to handle and measure liquid materials, non-contact radiation thermometry is far more common in pulse-heating than contact thermometry. Other reasons for non-contact temperature measurement methods include the fast heating rates and temperature gradients (inertia of the thermocouples), difficulties mounting the contact thermometers (good thermal contact needed), and stray pick-up in the thermocouple signal because the sample is electrically self-heated. 

---