An investigation of heat transfer gain with introduction of graphite powder to helium gas

Abstract

Analysis is made of heat transfer by turbulently flowing helium gas with suspended graphite particles in a circular pipe. At very high temperatures, the radiative heat to gas alone can be profoundly improved because of the large absorptivity of the cloud of fine particles. For every high temperature flow situation where radiation is the significant mode of heat transfer, there exists an optimum loading ratio (mass of graphite to that of He) and particle size for which maximum heat transfer rates are achieved. In this study, heat transfer phenomena are examined for a circular pipe with axial cosine temperature distribution and the mass of graphite, optimum particle size, and the influence of other parameters which will result in maximum heat transfer are determined. The heat transfer and flow situation are analysed for two cases. In case I, the thermodynamic parameters are averaged values of the lowest and possible highest temperatures. In case II, these parameters are temperature dependent. The governing equations for this particular system with radiation heat transfer are derived. (Authors)