As explained to me... - Saab 9-5 Bulletin Board - Saabnet.com
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As explained to me...
Posted by Stephen Goldberger [Email] (more from Stephen Goldberger) on Tue, 19 Jun 2012 03:13:47
In Reply to: Varible displacement compressor?, Mark from Toronto, Mon, 18 Jun 2012 13:55:39
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by someone I trust (also the best electrical engineer I know)
At low charge, the compressor outlet temperature is higher than than normal, resulting in more rapid deterioration of the high pressure hose.
Thinking about it, consider the perfect gas law. Pressure times volume = constant times mass times temperature. Pressure is fixed by the mechanics of the variable displacement compressor (that's how it regulates displacement - off the discharge pressure). Volume is fixed, then lower mass density is compensated by higher temperature. Ah, but what about the liquid part of the refrigerant inside the receiver? Doesn't it just get a little lower, essentially compensating for a low charge until it's so low that the liquid is negligible (and the system cooling is all but naught)? I don't have an answer for that, except that in a normal (fixed displacement compressor) system the outlet pressure increases in proportion to the charge volume (and low charge levels do not increase the compressor output temperature).
posted by 24.165.160...
Posts in this Thread:
- Anemic AC, Snowmobile , Mon, 18 Jun 2012 13:04:55
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