Phase-Change Thermal Control Schemes for High Speed/Power-Density Electric Machines

SatCon proposes to explore innovative phase-change thermal control schemes for high speed/power-density electric machines. Several cooling schemes will be investigated which utilize different physical mechanisms to drive the process. sy utilizing the fluid's latent heat of vaporization high power densities are possible. Some of these schemes utilize liquid jets to augment performance. The working fluid will be an inert perfluorinated liquid (e.g., 3M's Fluorinert) eliminating the threat of coolant leak induced electrical shorting. The peak heat flux for perfluorinated liquids at near-atmospheric pressures is in the range of 15-25 W/sq. cm. With jet impingement, up to a tenfold increase can be realized. In addition to being able to achieve high heat fluxes, direct liquid cooling reduces thermal gradients by transporting liquid over and/or into the machine's hot spot reqions. Phase I effort will consist of a qualitative ana quantitative evaluation of these two-phase cooling schemes. Analytical expressions will be developed that capture the fundamental mechanisms and characteristics of each scheme. A first-order model will be developed for the most feasible scheme that enables maximum motor-loads to be estimated. Phase II effort will concentrate on developing proof-of-principal experiments(s) and/or experimental prototype to demonstrate concepts and calibrate the model. Advances in manufacturing and electrical technologies have led to increased motor power-densities and associated thermal-control problems. Advances in thermal management would be highly beneficial to a wide spectrum of commercial industries ranging from industrial process equipment to gas turbine companies and satellite manufacturer. Potential applications include automotive and aerospace alternators/ generators, electric motors, portable generator sets, and power electronics, to name a few.