Study on the heat transfer characteristics of single-phase and two-phase impinging jets

Abstract

In this thesis, heat transfer characteristics of single-phase and two-phase impinging jets are investigated. The present research work is divided into two parts. One is a single-phase impinging jet part. The effects of pumping power, nozzle-to-plate spacing, degree of confinement, lateral conduction, and Prandtl number on the Nusselt number are considered. The results show that the Nusselt number is independent of the nozzle-to-plate spacing and the degree of confinement under fixed pumping power conditions. Based on the experimental results, a simple correlation for the Nusselt number is developed as a function of the pumping power and Prandtl number. In the two-phase impinging jet part, the effects of volumetric quality and nozzle diameter on the Nusselt number are considered. Air is used as the gas phase and water is used as the liquid phase. The results show that the Nusselt nuber has optimum point at around 0.2-0.3 of the volumetric quality. In addition, flow patterns of two-phase impinging jets are observed. The optimum point of the Nusselt number is in bubbly flow region. The Nusselt number is independent of the nozzle diameter. Based on the experimental results, a correlation for the normalized Nusselt number is developed as a function of the volumetric quality.