Correction for Calculation of Particle Heat Transfer in Thermal Plasma

摘要

One of the most widespread areas of plasma technology is a treatment of fine-dispersed materials in plasma jets. Complexity of an experimental research of the system "plasma flow-particles" has caused the creation of the mathematical models describing movement, heat transfer, and physical and chemical transformations of dispersed materials in plasma. Researches of heat transfer in high-temperature flows are of significant interest since heat transfer from plasma to powder particles is the determining factor. A number of studies of particle heat transfer in thermal plasma give the following expression for the Nusselt number: Nu = 2 + ARe{sup}0.5 P{sup}0.33r , where A is the constant. However, this expression overestimates Nu in comparison with experimental data. In this connection, the authors offer the dimensionless expression for calculation of particle heat transfer in plasma taking into account the correction for the conductive term: Nu = 2λ{sub}sV{sub}s/λ{sub}pV{sub}p + 0.6Re{sup}0.5Pr{sup}0.33. Introduction of the correction, namely v{sub}s/v{sup}p, obviously explains the mechanism of influence of the heat transfer conductive component on particle conductive-convective heat transfer in thermal plasma and results in sufficiently good agreement of calculations with numerous experimental data.