2) Based on my accumulated knowledge and hands-on experience, I can affirmatively state that while single-phase immersion cooling tends to deliver lower CAPEX, it usually implies a higher OPEX. In other words, while the initial cost might be lower, the running expenses over the long term can be significantly higher.
This is a serious claim, to say the least, as far as I understand the main pro of two-phase vs single-phase would be a slightly better PUE, I am not sure how two-phase system would have a lower OPEX by saving a few tens of dollars in pumps.
With two-phase you are still going to need to add new components that are not needed in a single phase, and the main issue with be the use of Fluorocarbon-based liquids, which are EXTREMELY expensive compared to the hydrocarbon-based liquid used in a single phase.
Here is a
study showing that the loss of the liquid was pretty high to the point that having that better PUE was questioned.
Now, personally speaking, the cost of the two-phase 75KW is $37,000. if we compare that to one of the single-phase setups, the total cost would be a lot less than 50%, I find it very difficult to justify such an investment, mining a short to medium-term business, if OPEX will only start to look better after 50 years then it's a no-go.
Thanks for answering my questions.