R507 in an R134a compressor: any danger?

[Gary]

Geez.
That means about 40ft/12m of 3/8" tubing, with a copper<->water surface area of 3591 cm2 (0.36m2/3.2 sq.ft) and a refrigerant<->copper surface area of 2912 cm2 (0.29 m2 / 2.6 sq.ft).

How much copper would be needed if you used 1/4" tubing? Or 1/8"?

How much refrigerant->copper->liquid surface area is used with those >20kW chillers you guys are used to work with? Those must be huge....

We aren't trying to achieve ultra low temperatures in those chillers. If you wanted above freezing water temperature in your system, then your current evaporator could easily do the job. The colder you want to go, the more surface area needed.

As I recall, all of the heat flow formulas have electrical flow formula equivalents, with TD representing voltage and heat flow representing amperage, if that helps. In adding surface area, we are lowering resistance.

Gary, I also have another question on which you might have a good opinion. I am using a water/methanol mixture as the secondary coolant. Based on numbers it should perform very well. And in my system if outperforms propylene glycol based automotive coolant hands down.

I have little experience with glycol chillers. I know that throughout the refrigeration industry, using automotive anti-freeze is considered a VERY bad idea. Beyond that, you probably know more about the subject than I do.

An ultra low temp liquid chiller is quite unique. Usually the product is chilled directly, but then, this application is unique in that the product to be cooled (CPU) is extremely small.

Using a liquid chiller for this purpose limits the potential, but has it's advantages also.