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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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.
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.
We cool things down by “moving” the heat somewhere else. That process of moving the heat creates heat by itself (no thermal cycle is 100% efficient, or more efficient than the ideal Carnot cycle) so that adds heat to the removed heat. We make more heat than the one we “removed”.
Nothing in Universe “cools down” by itself. The third law of thermodynamics says that system entropy always increases. Some say that is the only law that points to the existence of an “arrow of time”, how time flows only in one direction.
We cool things down by “moving” the heat somewhere else. That process of moving the heat creates heat by itself (no thermal cycle is 100% efficient, or more efficient than the ideal Carnot cycle) so that adds heat to the removed heat. We make more heat than the one we “removed”.
Nothing in Universe “cools down” by itself. The third law of thermodynamics says that system entropy always increases. Some say that is the only law that points to the existence of an “arrow of time”, how time flows only in one direction.
We cool things down by “moving” the heat somewhere else. That process of moving the heat creates heat by itself (no thermal cycle is 100% efficient, or more efficient than the ideal Carnot cycle) so that adds heat to the removed heat. We make more heat than the one we “removed”.
Nothing in Universe “cools down” by itself. The third law of thermodynamics says that system entropy always increases. Some say that is the only law that points to the existence of an “arrow of time”, how time flows only in one direction.
We give the object’s heat energy a path to follow so that it loses heat faster than it gains heat from other sources.
We give the object’s heat energy a path to follow so that it loses heat faster than it gains heat from other sources.
We give the object’s heat energy a path to follow so that it loses heat faster than it gains heat from other sources.
Heat always transfers and disperses through many different processes in an attempt to reach equilibrium, that is everything and everywhere being the same temperature. This is of course not possible, at least not in a time frame smaller than billions and billions of years and does not concern us.
The point is that heat transfers, and while the thermal conductivity of different materials may be different and some may be very good insulators, ultimately it’s not possible to entirely trap and maintain heat so it will eventually cool down. This is a process that we can accelerate and take advantage of to cool down objects or spaces for various reasons.
In the case of refrigerators or air conditioners the main way this is achieved is through essentially displacing the heat elsewhere, and if you do this fast enough you can lower the temperature faster than it can heat up from ambient temperature. Of course all that means that the heat has to go somewhere which is why the back of refridgerators or the external A/C units blow out fairly hot air when in operation, much warmer than the ambient air.
Heat always transfers and disperses through many different processes in an attempt to reach equilibrium, that is everything and everywhere being the same temperature. This is of course not possible, at least not in a time frame smaller than billions and billions of years and does not concern us.
The point is that heat transfers, and while the thermal conductivity of different materials may be different and some may be very good insulators, ultimately it’s not possible to entirely trap and maintain heat so it will eventually cool down. This is a process that we can accelerate and take advantage of to cool down objects or spaces for various reasons.
In the case of refrigerators or air conditioners the main way this is achieved is through essentially displacing the heat elsewhere, and if you do this fast enough you can lower the temperature faster than it can heat up from ambient temperature. Of course all that means that the heat has to go somewhere which is why the back of refridgerators or the external A/C units blow out fairly hot air when in operation, much warmer than the ambient air.
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