Free Piston Stirling Cooler able to cool down a room/house?

[BurntToast]

Hello all, brand new to this type of tech. Was wondering if a Free Piston Stirling Cooler (FPSC) is more efficient than lets just say a 30 Seer MiniSplit AC unit.

I'm looking to build/install an efficient cooler, current conditions, outside 95F inside, would want it lower than 76F inside. I know a FPSC is not practical, but is it able to efficiently cool a room/house, in addition to a whole AC unit (kind of a supplementation)? I don't mind running the PFSC 24/7.

I'm looking into comparing these units, relatively close in price. If there are suggestions to better units, please let me know.
PFSC: https://rigidchill.com/free-piston-stirling-cooler
MiniSplit: https://budgetheating.com/v/vspfiles/do ... mittal.pdf

[MikeB]

The specs available on that site, at least at first glance, are essentially non-existent. I wouldn't touch it with a barge pole, and in any case, what is being advertised is little more than a basic kit - you would have to do a lot of work to adapt it to actually cool anything.

[Tom Booth]

Probably in general, a Stirling cryocooler is more efficient. (Not necessarily that model, I don't know anything about it) but from the Department of Defense:

Stirling coolers are highly efficient and compact. For example, the high efficiency and compactness (and lightweight) of Stirling coolers have made Stirling coolers the dominant type of cooler for cooling space-based electronics. In theory, the Stirling refrigeration cycle can achieve the Carnot COP (the maximum possible COP) of
11.5

https://apps.dtic.mil/sti/pdfs/ADA561797.pdf

In theory at least.

Though as you say, probably not practical.

The extreme cryogenic cold produced would have to be far from any potential direct human (or pets, children etc.) contact, Maybe the cold finger could go in an air duct for a little extra cooling?

The other thing is these little units are only designed to cool a few square feet of air space so operate at just 100 watts or less.

Theoretically though, if the air was recirculated and the house extremely well insulated it might cool a house, eventually.

You also, though, have to somehow cool the hot side of the cryocooler for it to work effectively by venting off the waste heat in some way.

Another problem could be the tiny exchange area of the "cold finger".

Possibly you could attach a large aluminum grate or something to the cold finger for more surface area for direct air contact.

Also, the extreme cold exposed to a lot of humid air would tend to build up a lot of ice so it might need regular defrosting, and the ice acts as insulation also reducing efficiency, probably.

Though, maybe with enough surface area provided by an aluminum or copper "reverse heat sink" and continuous flow of hot air, the cold finger might just stay above freezing, but then you have to deal with a lot of condensation and would need a drain pan under the thing.

Maybe use the ice cold condensed water for cooling the hot side of the cryocooler.

It might make an interesting engineering project. As far as I know, there are not any commercially available Stirling cycle air conditioners. There probably should be though, both for efficiency and environmental concerns.

I'd say try it and let us know how it goes, though it might be a rather expensive waste of time.

[BurntToast]

Yeah I will possibly be living in a two story house. Was going to run it at the first story window, then open a window on the second story to vent out some of the heat that rises.

On the cold side, I was going to possibly extend the finger with a copper or aluminum depending what it's made out of. Even just dunking the cold side into a vat of mineral oil/3m Novec 7100 using old PC water cooling parts to exchange the inner house energy. If the hot side needed additional cooling, would also do water cooling on that side as well. Although, the water cooling parts would require probably 50W with 6x 120mm fans and and 2x pumps.

150w for the cryocooler system and 50w for additional exchanges = 200w x 24 hours = 4800w or 4.8kWh x 0.13 cents per kWh = 63 cents to run per day.

[Tom Booth]

...= 63 cents to run per day.

Sounds relatively cheap, if it worked.

60 cents might run the (normal) air conditioning for a few hours at the electric rates where I live.

[BurntToast]

...= 63 cents to run per day.

Sounds relatively cheap, if it worked.

60 cents might run the (normal) air conditioning for a few hours at the electric rates where I live.

Yeah 15 cents per kWh is on a summer peak hour. I know in CA, a regular price is 25 cents per kWh, 31 cents peak hour. Googled that San Fran is 34 cents on peak hour