Thursday, December 22, 2011

CryoBUG hits -140°C

Well hey I did it today, I passed another milestone, that being the -140°C mark!

Evap-Out (left), Evap-In (right)

So here's the charge that I used:

100 Grams R-134a (50 psig vapor pressure)
50 Grams R-23 (85 psi vapor pressure)
50 Grams R-14 (75 psi vapor pressure)
Added 35 psi of Argon (not possible to weigh it in)
Static Balance Pressure = 245 psig

Start-up initially hit a discharge pressure of 344 psig, with a discharge peak of 360 psig within 10 minutes, after which it began to drop. Below I have shown a graph of the Evaporator In & Out for temperature versus elapsed time in minutes to get a better idea of performance with this new charge and hardware configuration (previous cap tube changes).

As can be seen, the first 40 minutes yields an extremely fast pull-down in evaporator temperature, and then for the next hour or so the pace slows down quite a bit. And when we get to the 2 hour mark, things have pretty much leveled off.

Final running pressures at the end were 11 psig suction and 187 psig discharge, with a compressor discharge temperature of about 55°C. Current draw was actually quite low, at 2.5 Amps (compressor RLA = 4.3 Amps).

This thing is running beautifully, and well within spec for this R-410a rated compressor. I am continually amazed at how well this Fuderer hybrid performs. And I can't wait to see what it does with a properly designed Cold Head.

Stay tuned for more upcoming tests and data.


Anonymous said...


Please post a video onto Youtube of this. Just to hear and see it would be amazing. Thanks

Michael St. Pierre said...

Yes I'll have to do that, good idea. Perhaps on the next test run I'll get my chance.


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