January 2008
Figure 1 - NREL computational fluid dynamics simulation of jet impingement (green and red colors) on the backside of a power electronic device.
A paper authored by members of the power electronics group at NREL (titled "Numerical simulations of nucleate boiling in impinging jets: applications in power electronics cooling"), was recently published in the International Journal of Heat and Mass Transfer. This landmark study is the first time detailed numerical simulations of impinging jets with phase change have been validated with experimental results.
Jets with phase change are currently being explored to cool power electronics components in advanced hybrid vehicles. Numerical modeling of flows with phase change is particularly challenging because of the complex physics involved.
NREL researchers worked with an engineer from FLUENT Inc. to enhance a computational fluid dynamics (CFD) software by developing a nucleate boiling model for impinging jets. NREL researchers then used this model to simulate two-phase cooling, and validate it with experimental data (see figure 1). The findings show that in some cases two-phase jet impingement cooling of a power electronics package is significantly better than single-phase liquid jets. The study also showed cases where the single-phase liquid jets performed better than the two-phase jets.
The paper prompted Dr. Tim Shedd of the University of Wisconsin at Madison to say: "…this is the best, most successful example I've seen to date of simulation of jet/spray impingement…. I will definitely be using this paper as the standard that I will compare future works with. And it will be required reading for my students for sure."
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