Why can't heat pumps use air

[numtyhead]

I'm thinking about using an air compressor to take warm air and compress it to raise the temperature in order to heat up a water tank. Once some of the heat has been removed I would intend expanding the air before reheating in the same way as you would in a heat pump.

I have a couple of questions which I would appreciate some views on:-

1). Do systems exist as described above. If yes where can I get more information, if not why not?

2). I calculate the energy required to compress the air is the same as what would be required using conventional heating. If I expand the air in a piston / cylinder I should be able to recover some energy. However if I expand using a nozzle I cannot see where I can recover some of the energy used to compress the air. Can anybody explain what's going on here?

3). I'm unclear regarding the merits of either compressing the warm air removing the heat and then releasing to atmosphere compared with completing the cycle.

I studied thermodynamics some years ago but need to get some understanding of the basics involved here.

Any thoughts / help welcome.

Thanks Numtyhead

[ard[H20]]

Such design was used in the late 1800's aboard Sailing Steam Ships (SSS Minnow /eg). The compressed air was used to refrigerate cargo. Inefficient then, I doubt any advantage is to be gained today over a similar concept using conventional heat pump application. Be aware the engineering part of the water heating has to be precise.

ICE

[Tony]

Yes you can do that as long you have fat valet Tony

[Bubba]

[TH]

Takes a lot of compression to liquefy air

[SATAN]

Yes, air will work for a heat pump, but in my own experiences I have found out that certain types of air works better than other types of air.

The air that I have found to be particularly good for heating or cooling is the air that they put in those little cans of air that they sell at the electronics store. They call the can of compressed air "air dusters".

I don't know where they get the air but it generates a lot more heat when you compress it than the air that I find around here. They may be getting the air from mars or some other planet. It just may be a result of the air contaminants in the air around the air duster factory where they get the air from. I don't know, but it isn't really important.

All you have to do is use the air in the air dusters for you air compression system. You want to remember that you want to keep the air duster air separated from the air that you are breathing. Otherwise, I have found that the air loses it's good properties. It starts acting like the rest of the air that you and me are breathing.

To keep it separated, you have to make the system a closed loop. It goes from the compressor to the heat exchanger, then you have to uncompress the air by letting it pass through a restriction. When it uncompressed it will get really cold because it want to regain the heat that it just lost. Run it through another heat exchanger close to a heat source to allow it to regain it's heat, then feed that though the compressor again.

It seems to work a lot better than the same system with normal air in it. So the canned air definitely has some unique property that I haven't determined yet.

Hopefully the manufactures of the canned air don't find out about it's unique properties, because they may stop selling it so cheap. Heck, it's good enough that it could even replace that nasty refrigerant they keep complaining about. That would definitely make it worth more than they are selling it for in the stores.

Good luck with your experiments.

[geothermaljones]

That reminds me... I've got to run out & put the summer air in my tires. I recommend you all do the same.

gl goj stpmn

[<kjpro]

You mean to tell me, you don&#39;t use R410a to fill your tires.

What a cheap skate!

[Noon-Air]

R410a is too expensive, I use N2

[Michael Shell]

I remember that from somewhere:

"Jay Leno" wrote: : Another cool thing is this Ingersoll-Rand : nitrogen generator I have. People don&#39;t realize how corrosive the air : is-- it&#39;s especially bad for a car&#39;s aluminum wheels. A lot of times, : when you see old aluminum wheels, they&#39;re pitted on the inside. If you : fill the tires with pure nitrogen, the wheels stay like new. Also, the : pressure of a nitrogen-filled tire doesn&#39;t rise or fall like one filled : with air. Put 32 psi in your Corvette tires, go out and do a few : burnouts, and now you have 38 psi. But nitrogen won&#39;t do that. It stays : where you set it. The nice thing about this Ingersoll-Rand nitrogen : inflation system is that it&#39;s a generator, so it extracts the nitrogen : right out of the air--for free. You don&#39;t have to call a guy to bring : a huge tank of nitrogen. I&#39;m running nitrogen in everything now.

;)

Mike Shell

[hvacrmedic]

Is that supposed to mean something? Maybe you could expand a bit on that statement. I&#39;m not sure that the expression "the water heating has to be precise" even means anything in English.