Study on atomic sodium release from pulverised coal particles in a pre-mixed natural gas flame
Atomic sodium release during coal combustion has been shown to be a significant factor in fouling and corrosion of heat transfer surfaces within industrial coal-fired boilers. Although there has been significant research into the final forms of sodium from combustion, information about the release of sodium is limited. An initial study of the release of atomic sodium from pulverised coal particles in a pre-mixed natural gas flame was conducted using planar laser induced fluorescence, PLIF. Measurements were made of the intensity of sodium fluorescence, coal particle velocities and gas phase temperature within the flame in a purpose-designed laminar flame facility that provides similar time-temperatures history to coal particles in their early stages of combustion in an industrial coal-fired boiler. The velocity of the coal particles was measured to be about 6.1 m/s using particle streak velocimetry obtained from the natural luminescence of the hot particles and a 2.25 ms gate of the CCD camera. Temperatures were measured using thermocouples, and the maximum measured temperature was ~1500 °C. Calibration of the sodium fluorescence was not undertaken, but useful information was obtained of the release rate of sodium atoms from combusting pulverised coal particles.
Quantitative in-situ measurements of sodium release during the combustion of single coal particles using planar laser induced fluorescence.
v DECLARATION vii ACKNOWLEDGMENTS viii PREFACE x CHAPTER 1 – INTRODUCTION 1 1.1 Background 2 1.2 Scope and structure of thesis 4 CHAPTER 2 – LITERATURE REVIEW 7 2.
Thermally Induced Dynamics of Satellite Solar Panels
Thermally induced structural motions are known to affect the attitude dynamics of low Earth orbiting satellites during eclipse transitions. Motions of e exible appendages such as solar panels lead to rigid body rotations of the entire satellite because the total angular momentum of the system is conserved. These potentially large attitude disturbances may violate pointing accuracy and jitter requirements. One type of thermally induced dynamics exhibited by solar panels is thermal snap. The Upper Atmosphere Research Satellite is a prominent example of a satellite that experiences thermal snap disturbances during eclipse transitions. This paper describes recent studies of thermally induced dynamicsof solarpanels, including an analysisofsatelliteattitudedynamics resulting from thermally induced structural motions and a laboratory investigation of the thermal-structural performance of a satellite solar panel. Analytical and experimental results demonstrate thermal bending deformations with acceleration transients that have characteristic thermal snap disturbance histories in response to rapid changes in heating. The studies show that solar panel thermal snap disturbances are caused by through-the-thickness temperature differences that vary at a nonconstant rate. Finite element analysis correctly predicts the thermal snap phenomenon observed in the solar panel experiments.