I understand how we heat them, by putting energy into the system. but how do we use the energy to cool them down?
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To cool something down, you need to remove energy from it by transferring heat to something else. There are different ways to do this, like by putting the object in contact with something cooler, blowing air over it, or allowing it to radiate heat to cooler surroundings. Refrigeration and air conditioning are also specialized methods of cooling that use a combination of these processes. So basically, cooling is the opposite of heating – you’re taking energy away instead of adding it.
By removing the energy.
This is either by pumping it away, like in a fridge or air conditioner, or introducing it to something with less energy than it, like an ice cube.
Differences in temperature want to equalize, so sticking something cold with less energy and something hot with more energy, the heat energy will flow into the cold thing with less energy until everything has the same amount.
To cool something down, you need to remove energy from it by transferring heat to something else. There are different ways to do this, like by putting the object in contact with something cooler, blowing air over it, or allowing it to radiate heat to cooler surroundings. Refrigeration and air conditioning are also specialized methods of cooling that use a combination of these processes. So basically, cooling is the opposite of heating – you’re taking energy away instead of adding it.
The strategy is to take advantage of evaporation, condensation, and generally compression of a gas/fluid to move heat energy. We have a machine that uses the concepts of how a can of compressed air gets cold as you spray it in order to make itself cold in one location. This gas/fluid runs in a loop so that the supply of compressed air is continuous so we can keep “spraying” it and keep the cold coming, getting hot on one side and cold on the other. So it’s often called a “heat pump”, though the name tends to be specific to certain types of heating and cooling systems.
This is why air conditioners are always at least partially outside. There may be some outdoor unit outside your home connected by pipes, or it’s a machine you hang out your window. The hot air is just vented into the outside air. The cold air is blown into the building keeping it cool. A refrigerator gets warm behind and above itself, since that space is the “outside” for it.
By removing the energy.
This is either by pumping it away, like in a fridge or air conditioner, or introducing it to something with less energy than it, like an ice cube.
Differences in temperature want to equalize, so sticking something cold with less energy and something hot with more energy, the heat energy will flow into the cold thing with less energy until everything has the same amount.
We move heat to another location.
A refrigerator is a heat pump. There is a compressor that compresses the coolant. If you compress a gas the temperature increase. If you use a bicycle pump you will notice the nozzle gets warm.
The next step is to let the coolant run through a heat exchange with the environment. The environment is usually air. Passively or with air blown by a fan the coolant that is warmer than the air transfer heat to it. The air get warmer and the coolant cooler. A preferred heat exchange will result in both at the same temperature.
The next step is to let the coolant to a nozzle where it can expand in volume. A gas gets colder when it expands. That is why the nozzle of a spray can get cold.
The lower-pressure gas it no let through another heat exchange, It will be inside the refrigerator. The gas will be heated by stuff in the refrigerator. The coolant get warmer, and what is in the refrigerator get coolant. If the heat exchange was perfect both end up at the same temperature.
The next step is back to the compressor again.
So we could stuff down by moving heat. The energy the compressor us will become heat too. So more energy is radiated out to the air then was removed from the inside of the refrigerator. So there is a total increase in thermal energy even if we cool stuff.
So you can’t just cool something without heating up anything else too. That is the case if you do that with an external energy source, You can have a total decrease in temperature if you change the phase of something. You then have a change of energy from thermal to chemical potential energy. It will be limited by the amount of material you have available. Evaporating water is likely the most common example of this.
By removing the energy.
This is either by pumping it away, like in a fridge or air conditioner, or introducing it to something with less energy than it, like an ice cube.
Differences in temperature want to equalize, so sticking something cold with less energy and something hot with more energy, the heat energy will flow into the cold thing with less energy until everything has the same amount.
We move heat to another location.
A refrigerator is a heat pump. There is a compressor that compresses the coolant. If you compress a gas the temperature increase. If you use a bicycle pump you will notice the nozzle gets warm.
The next step is to let the coolant run through a heat exchange with the environment. The environment is usually air. Passively or with air blown by a fan the coolant that is warmer than the air transfer heat to it. The air get warmer and the coolant cooler. A preferred heat exchange will result in both at the same temperature.
The next step is to let the coolant to a nozzle where it can expand in volume. A gas gets colder when it expands. That is why the nozzle of a spray can get cold.
The lower-pressure gas it no let through another heat exchange, It will be inside the refrigerator. The gas will be heated by stuff in the refrigerator. The coolant get warmer, and what is in the refrigerator get coolant. If the heat exchange was perfect both end up at the same temperature.
The next step is back to the compressor again.
So we could stuff down by moving heat. The energy the compressor us will become heat too. So more energy is radiated out to the air then was removed from the inside of the refrigerator. So there is a total increase in thermal energy even if we cool stuff.
So you can’t just cool something without heating up anything else too. That is the case if you do that with an external energy source, You can have a total decrease in temperature if you change the phase of something. You then have a change of energy from thermal to chemical potential energy. It will be limited by the amount of material you have available. Evaporating water is likely the most common example of this.
We move heat to another location.
A refrigerator is a heat pump. There is a compressor that compresses the coolant. If you compress a gas the temperature increase. If you use a bicycle pump you will notice the nozzle gets warm.
The next step is to let the coolant run through a heat exchange with the environment. The environment is usually air. Passively or with air blown by a fan the coolant that is warmer than the air transfer heat to it. The air get warmer and the coolant cooler. A preferred heat exchange will result in both at the same temperature.
The next step is to let the coolant to a nozzle where it can expand in volume. A gas gets colder when it expands. That is why the nozzle of a spray can get cold.
The lower-pressure gas it no let through another heat exchange, It will be inside the refrigerator. The gas will be heated by stuff in the refrigerator. The coolant get warmer, and what is in the refrigerator get coolant. If the heat exchange was perfect both end up at the same temperature.
The next step is back to the compressor again.
So we could stuff down by moving heat. The energy the compressor us will become heat too. So more energy is radiated out to the air then was removed from the inside of the refrigerator. So there is a total increase in thermal energy even if we cool stuff.
So you can’t just cool something without heating up anything else too. That is the case if you do that with an external energy source, You can have a total decrease in temperature if you change the phase of something. You then have a change of energy from thermal to chemical potential energy. It will be limited by the amount of material you have available. Evaporating water is likely the most common example of this.
To cool something down, you need to remove energy from it by transferring heat to something else. There are different ways to do this, like by putting the object in contact with something cooler, blowing air over it, or allowing it to radiate heat to cooler surroundings. Refrigeration and air conditioning are also specialized methods of cooling that use a combination of these processes. So basically, cooling is the opposite of heating – you’re taking energy away instead of adding it.
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