Comp Exam presentation - Matthew Skuntz
- Tuesday, May 29, 2018 from 1:00pm to 2:00pm
- Barnard Hall, Room 126 - view map
Application of Magnetic Resonance Velocimetry and T2 Relaxation Thermometry to Investigate Pore-Scale Heat Transfer in Packed Beds
In this research, convective heat transfer in packed beds is investigated for flow-through systems, where heaty is transferred via fluid moving through pore space, and natural convection systems, where heat is transferred through the walls and fluid motion is due to differences in density. Packed bed heat transfer is relevant to many industrial applications, from chemical reactors to pebble bed nuclear reactors. This experimental setup is designed to imitate the packed beds used as thermal storage systems in Concentrated Solar Power (CSP) plants but can be applied to others and can be used to investigate the fundamentals of heat transfer in packed beds. CSP plants take advantage of the large amount of energy required for a material to change phase from a solid to a liquid to store energy for later use. By storing energy in a phase change material (PCM) a smaller packed bed can be used and energy transfer is more efficient. Here, encapsulated eicosane wax is used as the PCM and a fluorinated fluid is used to transfer heat to the PCM packed bed. The study of fluid flow and heat transfer in packed beds has been hindered by the inability of experimental techniques to measure velocities and temperatures on the interior of the packed bed. In packed beds analytical solutions become too complex due to the complexity of the interconnected pore space. Numerical models and direct computational simulations are used but need more detailed experimental information to reduce the errors associated with these approximation methods. A solution is investigated here, where the use of a wax and fluorinated fluid allows for the PCM packed bed and fluid pore space to be measured with nuclear magnetic resonance (NMR) techniques. The high concentration of hydrogen (1H) in the wax (PCM) and high concentration of 19F in the fluid allow the two to be measured at different frequencies without interference. This allows velocity and temperature measurements to both be collected in the packed bed. In this research, forced convective energy transport is investigated with this system in a liquid, supercritical fluid and near-critical fluid. Heat transfer due to natural convection is also investigated for these same fluids. The data collected experimentally will then be used to create computational fluid dynamics (CFD) models in the STAR CCM+ program and to define improved correlations for heat transfer in PCM systems.
- Department of Mechanical & Industrial Engineering