A while ago, I introduced this topic as a means of exploring ways to get more power out of the MGR. I'd like to return to that.
As is well known by folks in the motor design world, and is well illustrated in the tests by ORNL, cooling is a very important issue. That's great - because that's something that doesn't require a doctorate in EE to understand.
In fact a BS in ME will do just fine!
So, I started exploring the cooling in a bit more detail. When I first heard the MGR used oil spray cooling directly on the end windings, I thought they were just looking for the cheapest way to cool the motor. Not true. Actually it's one of the most effective ways to cool stuff. In fact the military is actualy working on direct spray cooling. Here are a couple of interesting links about it:
https://www.highpowermedia.com/blog/...oling-concepts
An Overview of Liquid Coolants for Electronics Cooling « Electronics Cooling Magazine – Focused on Thermal Management, TIMs, Fans, Heat Sinks, CFD Software, LEDs/Lighting
Spray Cooling Electrical and Electronic Equipment - COTS Journal
In the first link, it mentions that a typical passively cooled motor can handle 5-8A/mm^2. A cooling jacket will allow about 10-15A/mm^2. The highest ratings were for direct spray cooling: 30A/mm^2.
In the second link, a bunch of sooper-dooper coolants are mentioned.
In the third link, the military's interest in the topic is illustrated:
Quote:
Testing by Southern California Edison on a GE 85HP traction motor was significant and consistent with NAVSEA’s FIAL efficiency data. The GE 85HP traction motor was fully loaded and tested with air-cooling and spray cooling (Figure 2).
In the mid- to 3/4-loads, a 25% to 30% improvement in efficiency was reported with spray cooling. Also, a 10% improvement was reported at 85 HP load and a 15% improvement in sustained overload at 100 HP (total power, in direct contact with the liquid, exceeded 73,000 watts). The test rig and shaft were not designed to operate at higher loads; however, the designer indicated that sustained overloads of at least 200% of rated load were possible. The overload results show that the use of less costly, lighter and more efficient generators and motors in ship, air and spaceborne applications is possible with spray cooling.
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Wow! a 25% to 30% increase in efficiency! Also a 200% increase in the rated load!
I'm interested!
- E*clipse