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Head still intact and believe I understand most of it, but I REALLY need to take a A/C and refrigeration class at Vo-Tech!
I've been trying to understand that <A href="http://www.rawal.com/">Rawal Valve</A> for a <I>long time.</I>
Do I have this anywhere near correct?
It tries to vary the effective size of the expansion valve to maintain a constant evaporator temperature regardless of total (latent and sensible) heat of the air passing across the evaporator. In other words, it strives to maintain a constant rate of evaporator superheat regardless of load on the evaporator.
It does this by refusing to allow the evaporator to superheat beyond some point by forcing the condensing unit to de-superheat. Since this means that some of the low temp, low pressure vapor in the suction line to bypasses the compressor, the load on the the compressor is reduced.