Rotary compressor cooling

[davidk]

It's a long time since I can't explain myself about the following thing:

Motors of hermetic recip compressors, and scroll compressors are cooled by passing suction refrigerant, which, of course, usually has a low temperature; motor is placed into low pressure side. On the other side, the rotary compressors seems to be built "upside down": the induction motor is on the high pressure side, after the discharge port of the compressor. So, how is this motor cooled, since it's always staying in a very hot gas? On top of this, the compressor is usually wrapped in acoustic insulator, so it can't pass heat to surrounding air. I can't imagine why ALL the rotary compressors are built this way, with motor on the high pressure side.

Thank you!

[Gary]

The temperature in compressor heaven is about 70C/160F. You shouldn't be concerned until it is hot enough to boil water.

[moideen]

Rotary compressors have designed to work 100c to 120c.

[davidk]

Maybe it's something about thermodynamics, since the suction gas enters directly into compressor. There's no more superheat added by motor windings. There's another similar thread but there was no conclusion: http://www.refrigeration-engineer.com/forums/showthread.php?36612-Suction-amp-discharge-cooled-compressors

[hookster]

The rotary compressor on small scale units is cooled via the oil returns to the oil sump which is thereby cooled from the suction.

[K.R.Iyer]

davidk, not just the Rotary, even few make scrolls are made this way. They are called "high side" design - motor cooled by discharge gas. The hermetic recips and standard scrolls that we see in market are "low side" design. Both have their own merits and de-merits - as per their manufacturers. All hermetics - scrolls, rotaries and recips - depend on gas cooling and need not have to conduct heat thru' their shells.