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Wednesday, December 21, 2011

CryoBUG getting ready for re-test

Late yesterday I let the compressor suck in 60 grams (approximately 2 oz)  of PVE-FVC32D oil, and put the unit back on a vacuum pump for final evacuation overnight. I did this to make up the oil that was lost during my previous HXC flushing operation, and concerns about what may have been left behind in the original AC unit this compressor came out of.

The PVE oil is rated for a lower temperature then the POE that was in the compressor from the factory. Since the two oils are compatible with each other, they will blend and yield a mixture with a lower freezing point then the POE alone. PVE is also a superior oil to POE, and completely miscible with all HFC refrigerants, as well as oils used in older R-22 systems.

Free Sample Bottle I received from IDEMITSU

In a discussion going on at XtremeSystems Phase Change Forum, it was suggested that perhaps my earlier diagram of CryoBUG might be a bit confusing. So I thought about it and came up with what I think is a more easily understood drawing of what CryoBUG really looks like (see below).

CryoBUG Piping Diagram w/Thermocouple Locations

I hope this helps people to better understand what it is that I have built. And due to some of the proprietary aspects of the design, I have not spec'ed out the sizes on the heat exchangers or the cap tubes. Although I'm sure this won't stop someone from figuring it out on their own. But it will slow them down a bit none the less.

You'll see that I show a high pressure cut-out for the compressor. This is good design practice, and something that I strongly urge be implemented. However in my current prototype I have not installed this safety feature at this time. Of course I am also watching the unit like a hawk whenever it's running, and wouldn't think to leave it unattended. Later when things start looking more like they are in their final stages with the charge properly tuned, I'll definitely be installing a high pressure switch.

In a few more hours I'll be charging the unit. This will be the new initial charge spec:

100 Grams R-134a
50 Grams R-23
50 Grams R-14

I'll add the Argon later once I establish what the unit does without it. Besides it doesn't take much to push you over the top, so I got to be careful.

Not sure if I'll be re-testing the unit today, but for sure tomorrow.

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