Advanced Calibration of Pyrgeometer by Blackbody Radiation with Least Squares Technique Applied to an Improved Steady State Equation of Heat Transfer

摘要

References(13) Supplementary materials(1) Calibration of pyrgeometer was performed using blackbody radiation emitted from a conical cavity. For its improvement, optical processes in the pyrgeometer were reconsidered, and a detailed steady state equation of heat transfer was derived. The equation additionally includes three factors; 1) heat transfer between sensor and body, 2) heat transfer from sensor to the air or gas in the body and dome, and 3) form factor for the convergence of dome radiation. Expansion coefficients or calibration parameters in the equation were determined precisely by least squares technique with the experimental data of temperatures and thermopile voltages. In addition, the coefficients were evaluated for the first time theoretically with numerical values of optical properties of its components such as dome, sensor and body. It is successfully demonstrated that both coefficients well agree with each other at a special value of thermopile constant, while there was no agreement in the past investigations.