Should I build an air cycle machine?

[akio123008]

I am considering building an air cycle machine that can be used to universally cool equipment, and possibly the entire room during hot days too. An air cycle machine operates in a very similar way to a regular air conditioner/ refrigerator, but instead of compressing/decompressing a freon-like refrigerant, it uses air. The benefit of using air as a refrigerant, is that it can be released directly into the environment that needs to be cooled, whereas regular phase-change refrigerants have to go through another heat exchanger in order to stay within the closed system loop.

 

The system is mainly used on aeroplanes, but as it's easier for me to build than a vapor-compression based unit, I thought why not use it to cool my room/ my computer etc. What are your thoughts on this? Have you tried it? would it be a good idea to cool water, and then use the water to cool other things? How about cooling the "hot side" of the unit with water? Are you aware of some other cooling solution I could use instead? I highly appreciate any suggestions, thanks in advance!

[Bitter]

I'm not sure how quiet venting liquid air into a closed room would be and I'm fairly sure the energy input needed to run it would exceed what a conventional AC unit would consume. I'm not especially well versed in air cycle but I know air in a R134a system causes a host of issues because the pressures needed to run it as a refrigerant are much higher.

[HanZie82]

I know the summer at the moment is really hot here.
But i dont think that is a viable solution since the efficiency of a closed loop is so much higher.
Like @Bitter said it will be noisy and will cost a lot of energy.

Maybe save up and buy an AC unit in the winter from Marktplaats.
I keep forgetting to do that tho. ugh.

[akio123008]

 

28 minutes ago, Bitter said:

I'm not sure how quiet venting liquid air into a closed room would be and I'm fairly sure the energy input needed to run it would exceed what a conventional AC unit would consume. I'm not especially well versed in air cycle but I know air in a R134a system causes a host of issues because the pressures needed to run it as a refrigerant are much higher.

This type of machine doesn't liquify the air, the heating/cooling effect is achieved just by compression/decompression without a phase change occuring. A compressor compresses the air, warming it up, the air is then cooled to ambient temperature in a heat exchanger outside the room, and finally the cold compressed air is decompressed, therefore it cools down below ambient temperature, after which it can be released into the room. The reason the air cycle is less efficient than the vapor-compression cycle is because of the fact that there's no phase change involved. However, even though the effeciency is low, the system is still usable on aircraft, so why not in a room? Also, noise isn't an issue at all, if I can get this to work, I'd be fine with it, regardless of how loud it is.

 

21 minutes ago, HanZie82 said:

Maybe save up and buy an AC unit in the winter from Marktplaats.
I keep forgetting to do that tho. ugh.

But that wouldn't be fun would it? 

[Bitter]

Ok I mean sure try it but you'll need to hit atleast 100 psi and manage condensation/icing if it's humid. In US dollars you'd be laying out like $1000+ in equipment to be able to run it continuously, you'll exhaust a small tank quickly and have to wait a long time to re-fill and cool it.

[HanZie82]

9 hours ago, akio123008 said:

But that wouldn't be fun would it? 

Well if you want the fun, might i suggest something like this:

Added benefit no need for expensive high presure systems. (Or even closed loop systems).

[akio123008]

5 hours ago, HanZie82 said:

Well if you want the fun, might i suggest something like this:

Added benefit no need for expensive high presure systems. (Or even closed loop systems).

Haha I've actually watched the entire thing already; I have my doubts about the design though; the whole thing seems quite bulky, and a bit overcomplicated too. The man uses evaporative cooling to cool the air, then dehumidifies the air using some salt solution, and then he cools this salt solution with evaporation as well. I suppose in a proper system this second evaporator would have to be on the roof of the building or something. Here's what thought; why not just put the first evaporator outside the building like a cooling tower and pump the water through a heat exchanger indoors, to cool the air that way? That would eliminate the need for dehumidification. I can imagine it also reduces the efficiency a bit though, as the humid air that is dumped outside is also cooled for no reason.