I’m talking about air conditioning. Why can’t we just use the ambient energy to move the excess energy out of the room somehow?
In: Engineering
In order to remove heat from a room, you have to have it absorbed by something, then that something release the heat outside of the room.
So what we do is use a gas that we compress (which takes a lot of energy) then run the air over the compressed gas while it’s being expanded, which absorbs the heat, then we pump the gas back outside of the room where it get’s re-compressed and sheds it’s head.
Ever take a can of canned air and hold it down for a while? the outside of the can gets icy. It’s kinda the same concept.
There is no way to use the heat to remove the heat. The heat in the room doesn’t contain enough energy to remove itself.
The only reason energy will leave a room is if there’s less of it in another (hot inside and cold outside for instance) and it’s balancing itself out. The same is true for fluids, like water and air. So if we want to move it we need to do something. And no matter what that something is, it’s going to take energy to do.
We can, that’s called opening a window or natural ventilation. The problem is that its not particularly quick in most scenarios, and often times ambient energy levels are as high or higher than the interior ones.
In order to increase the rate of energy transfer we need to add energy in the form of work done by the compressor in an air conditioner (or just the motor of a fan). Many people want to increase that rate so that the steady state condition (where it ends up sitting) of the energy in – energy out equation is at an average energy (temperature) they feel comfortable at.
I think what you’re missing here is that heat is the ‘lowest’, most basic form of energy. Almost every interaction and energy transformation produces heat as a byproduct, and nothing makes any other form of energy using heat.
Two masses collide? Heat.
Two masses rub against each other? Heat.
Light hits something? Heat.
Sound goes through something? Heat.
Most chemical reactions produce heat.
Nuclear fission and fusion produce heat.
The only way we’ve come up with to “convert” heat into another form of energy is by making hot gasses rise through a turbine. But even that is really the atmospheric pressure pushing the hot gasses up, which is ultimately gravitational potential energy and not heat.
It’s helpful to think of types of energy as in a hierarchy. A form of energy is more useful if it can be converted into a lot of other forms of energy. By this definition, heat is the least useful type of energy. There is virtually no way to convert heat into anything else, any action performed will only increase the overall heat.
This ties into entropy somehow but I don’t know enough thermodynamics to say anything specific.
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