High Ambient Temperature Heat Flux Calibration System

摘要

In this contract Vatell Corporation explored source and temperature controlconcepts for high ambient temperature heat flux calibration. Three alternative calibration methods were studied: (1) concentrated high intensity light radiation, (2) heated graphite block radiation and (3) convection. Neither the graphite block method nor the convection method could match the temperature and heat flux range of the concentrated high intensity light method, which was selected for development of a preliminary system design. The best currently available equipment and technology for radiation calibration were combined in the design, to achieve calibrations at up to 815C with heat fluxes of up to 1136 W/cm2. A tentative list of equipment, including costs, was compiled for the system. Methods for separate measurements of convective and radiative flux at a surface were explored analytically. An experimental method was proposed for possible evaluation and test. The method uses two Heat Flux Microsensors with different emissivities on a single probe or surface, and enables computation of the relationship between emissivity and heat flux at the surface. A new type of heat flux standard was proposed which would be referenced to electrical measurements instead of radiation. If this device could be demonstrated and proven, it might ultimately replace the slug calorimeter as the standard sensor in heat flux calibrators.