Is there a way to make an air conditioner for when you can’t vent the heat outdoors?
Can you trap the heat in an object or convert it to another form of energy?
For example, could you transfer the heat through an electrical outlet?
I would be looking for replacing an in-window air conditioner for a room rather than providing AC for a house.
My situation is that I can't vent into ground or attic or window. But I appreciate learning if that possibility opens up.
The possibilities of transforming heat into any other form of energy are limited by the second law of thermodynamics. Essentially, you cannot simultaneously lower the entropy in a closed system (e.g your house) by transforming heat into a different form of energy, and transferring heat from a colder object to a hotter one requires work, so that more heat is produced in the second object than eliminated from the first. This (heat transfer from a colder body to a hotter one) is exactly what an air conditioner does.
Dumping heat into an electrical outlet while cooling your house is what a perpetual motion machine of the second kind would do.
The ceiling fan doesn't cool down anything, it only produces additional heat (though not much). It gives you a cold sensation is because it promotes air circulation, which improves heat/water exchange with your skin. If the air is colder than 36°C or below 100% humidity, it will carry heat away. If the air is hot and humid, the fan will actually make you feel hotter.
Watercooled , if you don't count sewer as "outdoors".
Use a (largish) water tank.
I've never seen a water tank used as a heat sink for an air conditioner, but they were used for stationary engines some time ago.
Typical air conditioners can produce about 2 kW of heat. If that heat is released in a 500 litter water tank:
$$\frac {2 kW}{500 kg}\cdot\frac{1 kJ/s}{1 kW}\cdot\frac{0.24 kJ}{1 kcal}\cdot\frac{0.24 K\cdot kg}{1 kcal}\cdot\frac{3600 s}{1h}=\frac{2\cdot 0.24\cdot 3600}{500}K/h=3.456 K/h$$
If my maths are right, a 500 litter tank temperature will increase less than 5 ºC per hour when the air conditioner is working at full range. That makes for several hours before it becomes too warm to be a problem. If it isn't enough you just need to make the water tank larger.
Of course, you end with a large tank of warm to hot water inside your home and you need to move the heat and water outside. The obvious solution is to place the water tank outside, but other ways might fit better your circumstances - for example, taking the tank outside every evening using a pallet jack.
Another answer suggests using water and discharging it into the drain, which is quite equivalent to emptying the tank, but that would waste an insane amount of water - unless there is plenty of free water at your place.
And as an end note, I would forget about extracting energy from the stored heat unless you have a practical use for warm water, but you may enjoy the pleasure of a warm bath after a long day working under the air conditioner.
This question reminds of the concept of a heat bank, a form of heating I experienced in the 1970s. The type of heat bank I am familiar with consisted of a metal box which contained an electric radiator and large quantities of steel which were heated by the radiator.
The concept was the radiator was energized during the night when cheaper off peak electricity rates applied and heat was stored in the steel plates. During the day, the electric radiator was turned off and heat from the metal plates radiated into the room with the heat bank.
The waste heat from an air conditioning unit could be stored like this, but the amount of heat produced by an air conditioner would be small by comparison. The other question that arises is what is then done with the stored heat. In a hot climate it would not be easily used.
Nobody specifically mentioned geothermal yet but this is exactly the principal used here.
Rather than exchanging heat with the outdoor air, heat is exchanged with the ground a meter or two below the surface.
I suppose one could make the argument that this is still "outside" but the heat does not make it to the atmosphere and if you have a heating/cooling geothermal unit, the heat that is stored in the ground during the summer cooling season will be used when heating is needed in cooler weather.
I have never seen a geothermal window unit but it would be possible in theory.
Surprised they haven’t been mentioned yet because they seem to be all the rage in the spammy ads you see on a lot of sites, but depending (very heavily) on the general atmospheric conditions, an evaporative cooler (sometimes called a swamp cooler) might work.
Evaporative cooling in general is based around the idea of latent heat of vaporization. In short, evaporation requires energy to happen, and that energy is almost always in the form of heat absorbed from the surrounding atmosphere. The actual amount of energy required is inversely correlated with how readily the liquid evaporates, and water actually takes a pretty significant amount of energy (roughly 2.25 kJ/g), so there’s a non-trivial cooling effect on the surrounding air just from water evaporating.
An evaporative cooler takes advantage of this by utilizing a reservoir of water and some sort of apparatus to provide a high surface area for the evaporation to happen (most comercial designs use specialized wicks), and often some mechanism to increase airflow as well. Under ideal conditions, a good evaporative cooler can easily translate to a cooling effect of multiple degrees celsius.
The big downside to an evaporative cooler is that ‘ideal conditions’ part. For it to work well, you need to be in a relatively dry climate. In the continental US for example, they work great in most parts of Arizona, Nevada, Utah and New Mexico, but are kind of useless in places like Florida, Georgia, or Louisiana due to the relatively high average humidity. You also have to keep it topped up with water, and generally have to make a point to keep it clean (it’s stagnant water, so you will get microbial growth if you don’t clean it regularly, and it will tend to smell rather bad).
There are phase change materials (Similar to the cold pack for injuries) that at some point in time was the all the rage. Basically what they did was storing and releasing heat energy. However, they have a limited capacity.
Figure: Phase change material in the form of a cold pack The idea is (or was because it never caught on) that the phase change materials are introduced into the walls/structural elements of a house, and they passively collect and release temperature around the set temperature.
Figure 2: how a phase change material works (source: steemkr.com)
Regarding the problem at hand "Is there a way to make an air conditioner for when you can’t vent the heat outdoors?", IMHO the answer is no - at least for applications which are the size of the house, and for large periods of time.
Update : regarding whether the heat can be converted to electrical energy and released to the environment
The problem is that you need to convert the heat energy to another form. To do that you need some kind of thermal machine. The efficiency of thermal machines is bound theoretically from the Carnot efficiency which is depended on the ambient temperature and the medium.
Since you are talking about a house, I'll assume a temperature of 23 °C as the desired and 33 °C(ambient) then the carnot efficiency is at best:
$$n_{th} = 1 - \frac{273+ 23}{273+ 33}= 3.27\% $$
So only a small portion of the energy can be converted and the rest will remain heat.
Heat can be converted to electricity only according to the second law of thermodynamics: you need in this case a hot reservoir and a cold reservoir. The heat engine takes heat from the hot reservoir and puts it into the cold reservoir. That's the way all heat-based electricity generation works. In gas-fired generation, the hot reservoir is very hot (it's actually inside the turbine/engine and can be several thousand Celcius) and you get a good efficiency of 50% if you put a steam turbine after the gas turbine (combined cycle generation). In coal power, it's 600 degrees Celcius and you get an efficiency of 35-40%. In light water nuclear reactors, the temperature is 300 degrees Celcius and you get an efficiency of only 30%. These efficiency figures assume the heat can be rejected to a cold reservoir of 0-30 degrees Celsius, which is usually possible. A very hot day on a very hot climate could reduce the efficiency somewhat.
If you want to convert heat inside your house to electrical energy, you need two conditions to be true:
In this case, typical temperature differences are below 10 degrees Celsius compared to 300-1000 degrees Celsius as used in commercial energy generation. So the efficiency would be so poor it's not worth pursuing. A fan is a better and cheaper option. Although a fan uses little bit of energy, it's far more efficient in directing the heat outside the house. Natural circulation would be horribly slow. An electricity generator operating on the temperature difference would probably be even slower.
If the outdoors is hotter than the indoors, then you need active energy to vent the heat outdoors. That's the electricity input to your air conditioner. Sometimes, even if the outdoors is colder than the indoors but not by a very large margin, you will want to use the air conditioner anyway as it's faster to cool than a fan.
You could in theory trap the heat to ice, but then you need a constant supply of ice, and you need to somehow get rid of the melt water, possibly through the drain, which would effectively be your way of venting heat outside.
However, it could be theoretically the case that disposing of heat by directly venting it outdoors as hot air is impractical but disposing of melt water not so impractical. Unfortunately, getting all that ice will be difficult. Ice was used to cool houses before the advent of air conditioning, and air conditioning replaced ice due to being far more practical.
Most houses have forced air ventilation. It might be feasible to get rid of the rejected heat through that ventilation system.
When situated in the old industrial building, once we had a "cooling system" that was simply sucking in the air through the hole in the floor from the accessible there labyrinth of the industrial underground tunnels. I do not know how productive this would be in a large scale but worked well enough for a small server room, using electricity only to drive the fan.
Edit 1 based on the current version of the question "Where can heat be vented from an air conditioner that isn't outside, in the attic, or into the ground?"
Answer: It is possible to put the heat into something like a large water tank. The problem is that you have to take the heat out of the water tank eventually. This is the heat battery concept. In a practical sense, when your available resources is that you have a room you can't even fit a regular air conditioner to, you're just going to be hot.
You can also try to use an evaporative cooler. These are sometimes called swamp coolers. Here's the issue: These only work in very dry environments. In most of the USA (assumed from your use of degrees F), using one of these will just turn your room into a sauna.
New question 2: How does a ceiling fan fit? A ceiling fan, being an electrical device, will add some amount of heat to the room. This is probably insignificant compared to the environment and other loads. What a ceiling fan does is makes it feel cooler in the room because moving air cools you down, at least as long as you can sweat. There are edge conditions in the southwestern US where blowing very hot air across your skin actually heats you up, but in most places, blowing a fan at you makes you feel cooler.
Let's examine what we're trying to do.
An air conditioner is a device that pumps heat from cold to hot, getting by the whole heat-flows-only-from-from-hot-to-cold thing. The cool thing about it (no pun intended) is that you can move more heat than the energy you put in to the device.
Now, let's discuss what the heat is we're moving. Heat is typically divided into latent (humidity) and sensible (temperature) heat. Your heat in your room comes from several sources:
So, what can we do with this heat we are removing? Practically, almost nothing. The expense to turn that low-temperature heat into work that you or someone else could use is more than it's worth. Other answers note the idea of heat batteries. If you happen to live in one of the places where it is hot during the day and cold at night you could store the heat and let it out at night. The thing is, it's probably easier to just let the hot daytime heat up that battery anyway (desert communities have done this through building materials for millennia). Adding complexity to electrical/mechanical systems costs more for minor paybacks.
We could do things for fun, like Peltier devices that make enough electricity to maybe charge a phone, or Stirling engines for the fun of it, but these aren't scalable solutions.
So, in summary, just enjoy the cool and worry about other things.
Theoretically? Sure. From a practical standpoint? No.
At least, it's pretty hard to see that working in any feasible way. Regardless of what you do with the waste heat, you would need an inexhaustible supply of fresh air to cool the hot refrigerant. So the question is what to do with that hot air. As someone suggested, you could cool that with, say, water cooling by creating a 2nd heat exchanger in your air exhaust. Provided the back pressure was low enough that the performance of the A/C was not impacted, which is doubtful. So you would still be exhausting air, even if cool air, except be paying a water bill for constant water circulation.
So if you're talking about cooling a real room, it's hard to see it being feasible without simply exhausting hot air like normal.
Answers to some of your queries:
I bought this in a hardware store a few months ago and tried to use it in my car bc my AC would take 20 mins to cool the interior (98' F weather).
Your car AC is faulty.
The air was sortof cool but it seemed like it wasn't any cooler than what I had in my car and it said it works better when you freeze some of the components.
It sounds like it is using ice to "store cold" and you're sinking heat into it during the melting phase.
I pulled it out of storage last night and it didn't seem much cooler in the room.
But it was worth it for the coloured LEDs? (They should have been a clue.)
A friend once said that if I don't have an AC unit the ceiling fan would generate more heat than it would be at cooling me down. I know heat rises so it makes sense but is this statement true or false?
Bringing in electrical electrical energy to run the fan will result in heating the room by a small amount. Fans do not change the temperature of the air. They provide increased cooling to skin by increasing the airflow across the skin which in turn increases the heat transfer rate from skin to the air. But cooling can only happen if the air temperature is less than body temperature (37°C) by at least a few degrees.
I have a water cooled air conditioner. It takes cool water in and returns hot water to the floor drain, cooling the room next door.
I'm surprised nobody has mentioned infrared radiation. Supposedly somebody has invented a paint that reflects so much energy that the self-radiation of its surface is greater than the incoming radiation, and it cools down below ambient temperature.
Heat's gotta go somewhere? One idea would be to deposit underground in geothermal coils.........
