[NiHaoMike]

From my understanding, she built an air conditioner that could operate as an indirect evaporative cooler or as a normal A/C with an evaporative condenser. What was notable was the use of water as a refrigerant, which had problems with needing a very high volume flow rate to get a usable capacity due to its low vapor pressure. The flow rate of a compressor increases with RPM, so her solution was to use a compressor that spins extremely fast (up to 100k RPMs or more, as opposed to 3600 RPM for a conventional compressor) in order to get the needed flow rate in a compact unit. Also notable was the use of a switched reluctance motor, which interestingly was invented over 150 years ago, but wasn't widely used due to limitations in control technology.

The large refrigerant charge is not an issue when even distilled water is dirt cheap. Lubrication is indeed one of the harder problems to solve, and it's one of her trade secrets. But still, 40 SEER equivalent with the most environmentally friendly refrigerant is setting a new future for energy efficiency, though mass producing that compressor is going to be a tough problem to solve...