Not proposing a viable process here, just using it as a thought experiment.
Suppose I took a small air-conditioning set up and made a few modifications. Instead of a fan blowing over the condenser and the evaporator I had them both submersed in liquid. This would theoretically be a still. The water cooling the evaporator would never get over 212 degrees as it would evaporate off at that point. The steam that came off of the water tank would flow into a condenser that was submersed in the same tank that the evaporator was submersed in. This would be a closed system. Energy would be added to power the a/c compressor. If a gasoline motor was used for power you could also use the exhaust to heat the water. I know this would be terribly inefficient compared to other methods but would it work?. And how inefficient would it be?
Inefficient at what? I’m not sure what this thing is supposed to do.
Near as I can tell you a bunch of stuff inside a water tank with energy being added with the end result of making the water in the tank warmer in direct proportion to the amount of energy added.
It is a still, it is heating and cooling
If you are asking if you can use a heat pump to heat water, yes, you can. And it’s actually much more efficient than resistive heating. I don’t know about your setup, though. You would want the input and output to be in different mediums.
Problem is, is that it’s hard to do it in one stage, most refrigeration systems don’t like to have such a large difference between input and output. Your home AC is calibrated for expected temperatures and desired cooling. If you wanted to use it in Death valley during the summer to cool your domicile to 50 degrees F, it simply wouldn’t be able to do it.
In the OP I said that was a still.
What do you mean by a “still”? Do you mean a distillery?
If so, not really, it’s not. If not, what do you mean?
Yes, a distillery
And why are you putting both the evaporator and condenser in it?
Like I said, you can heat water more efficiently with a heat pump, but you’d have the evaporator on the outside in order to absorb the heat from the ambient environment, and then the condenser in the liquid to reject that heat into your fluid.
If you just ripped parts out of a window AC unit, it would not work. You’d have to have the pressure calibrated to have the heat differential you are looking for, and I’m not sure that any common refrigerants would have enough range.
It’s several times more efficient than resistive heating, but obviously mechanically much more complex, especially if you are trying to bring water up to boiling.
No the evaporator would be used to cool the vapor coming off of the still and condensing it back into liquid.
This thing is plugged into a wall, and is getting energy from there. All of that energy is getting converted to heat, and it’s probably mostly heating up your water bath. So far, simple enough: Just about anything you plug in will work that same way.
Your device might also, in addition, be taking heat from someplace else, and adding that heat to the water bath, too. If that’s the case, then you could be heating up the water bath to a greater degree than you would with most devices you could plug in, in exchange for also cooling off something else.
So, what is that other thing that you’re cooling off? Air? A different water bath? If it’s the same water bath, then there’s no benefit, because you’ll be both heating and cooling it, and the net effect would be to just heat it up at the rate it’s drawing energy from the wall socket.
The water bath for the condenser would be product that was being distilled. I would leave the water bath as steam between 170 to about 205 and head to the condenser where it would be cooled by the evaporator by way of sharing a common water bath.
So, the set up is:
A small AC unit, submerged underwater and then sealed in a box?
Think about it this way, you have a normal still in operation. You remove the heating element and replace it with an a/c condenser, then you go over to your still condenser and it will already be in a water batch with circulating water, You cut off the circulating water and drop the evaporator into the cooling tank with the still condenser. If you were to actually build it both the a/c compressor and evaporators would just become coils.
It seems like the evaporator water would eventually get too hot but not sure I am looking at it right.
In a heat pump, the evaporator is the thing that does the cooling, collecting heat from whatever’s on its exterior surface. It’s the part of the system that cools your house, or the inside of your fridge/freezer. It’s called the evaporator because the refrigerant inside it is turning from a warm liquid to a cold gas (evaporating).
The condenser is the thing that dumps heat to whatever’s on its exterior surface. It’s the hot thing sitting behind your house, or on the outside of your fridge/freezer. It’s called the condenser because the refrigerant inside is turning from a hot gas to a warm liquid (condensing).
So if you’re trying to use a heat pump to operate a still, you’d boil your liquid at the outer surface of the condenser, and then condense it on the outside of the evaporator.
A heat pump takes less energy from you to heat something than simply supplying all the heat yourself. However, their efficiency goes down as the temperature difference between the hot side and cold side increases. heat pumps require mechanical or electrical power to do their thing, and if you’re deriving that mechanical/electrical power from a heat engine (e.g. a thermal power plant or maybe a portable generator), it’s likely more cost effective to just burn your fuel and use that heat to directly operate the still.
That would help, but you’d also want to somehow harvest the engine’s cooling load; in very rough terms, an IC engine operating at full load will give you 1/3 of the fuel’s energy as mechanical work, 1/3 as heat in the exhaust stream, and 1/3 as heat in the cooling system.
Sure, this would work. It would be more efficient than resistive heating, but those savings would be offset to some extent by the complexity and maintenance required for such a thing.
But, as I said upthread, this would have to be specifically designed and calibrated for this purpose. If you just cannibalized a window AC unit, it wouldn’t work.
If they were in a closed system, that would possibly be a problem.
So you have hot vapor coming off your still. You use an evaporator to remove heat from the vapor, aka cool it down. The evaporator takes that heat from the vapor and moves it to a condenser submerged in a liquid, causing the liquid to heat up.
There are heat pump water heaters that work this way. They move heat from the environment and concentrate it in the hot water tank. If you make the environment a box containing your hot vapor instead of just “outside”, then you’ll cool the hot vapor, and heat the water in the tank.
Then you want to bump it up a step. Have the liquid receiving the heat be the liquid you want to boil in the first place. So use your condenser to preheat your liquid, then move the heated liquid to a boiler, or you might be able to heat the liquid enough to vaporize it.
Actually getting it working efficiently is probably much more difficult than hacking up an old window unit AC.
This question would benefit greatly from a quick sketch.
The more I think about it I don’t think it would work. You would have to add a secondary evaporator to add heat from the atmosphere that could also be used to regulate temperature. In a closed system the total amount of heat you would have is what you started with in the two containers of liquid. The evaporator tank would give away its ambient heat and the condenser tank ( Still) would still not be anywhere near hot enough to operate.