Mike Cheadle PhD Graduate Student Mechanical Engineering Thesis: Determination of Oscillating Flow Heat Transfer and Hydrodynamic Parameters for a Cryogenic Regenerator

Regenerator models used by designers are macro-scale models that do not explicitly consider the interaction between the fluid and solid matrix. Correlations of Nusselt number and pressure drop used to calculate heat transfer and pressure drop, respectively, are based on steady flow data rather than oscillating flow data. The error from using these correlations is unknown. Experimental data for oscillating flow friction factor and Nusselt number exist in the literature, but results are conflicting. Some studies suggest oscillations have no effect and others suggest that the friction factor and Nusselt number increase substantially to their steady flow values. CFD modeling of oscillating flow is limited to macro-scale porous media models. Micro-scale CFD modeling and experimental measurements are being performed to determine the effects of oscillating flow on the heat transfer and hydrodynamic parameters of a cryogenic regenerator. Determination of Oscillating Flow Heat Transfer and Hydrodynamic Parameters for a Cryogenic Regenerator

CFD Modeling Strategy Regenerator unit cell Micro-scale CFD model of a unit cell (or multiple unit cells) of the regenerator matrix in order to derive oscillating flow correlations for Nusselt number and friction factor. Uniform inlet velocity, Uniform heat flux, Uniform outlet pressure, 12n Symmetry boundary He Multiple Unit Cells

Experimental Schematic compressorregenerator matrix aftercooler reservoir heater Schematic of the experimental apparatus that will be used to determine oscillating flow correlations for Nusselt number and friction factor. P T P T Pressure measurement Temperature measurement P T P T P T