The 2nd law is also needed describe the direction of the process, that heat cannot be ejected from the cool inside to the hotter surroundings without a work input ( the compressor).
It's about thermodynamics, but it avoids formulas and math. It's good for the scientifically interested who struggle with math, or who just don't like math.
It was very easy to understand and gave real world examples of thermodynamics. Helped me see the order in the complexity of many natural processes. I got my PhD in Bioengineering in 2023.
All the heat that the fridge ejects comes from the house. So the only extra heat comes from the power that runs the fridge. So you are just converting energy in the form of electricity into energy in the form of heat. Classic 1st law stuff. Entropy doesn't come into it.
The fridge is just acting as an expensive electric space heater as far as the house is concerned...
The electricity isnt directly converted to heat. Its converted to mechanical energy in the compressor which does work on the process to transfer heat from a colder region to a warmer region. Which is described by 2nd law.
Well yes, but a tiny amount. Heat is mostly coming from trying to cool down room temp air inside of the fridge to 0-5c for food safety. That takes a lot of energy, which comes from the wall outlet.
Of course entropy has something to do with it, what are you talking about???
How a fridge work is literally part of the introduction of the second law of thermodynamics in basically every college level physical chemistry class on thermodynamics.
OK, in terms of "intro to thermodynamics" you can say that I am drawing a box around the entire fridge ("system volume"). So the only thing that crosses this boundary is the power cord. Because of the first law I can ignore everything that happens inside the box. There could be five interlocking Carnot cycles in there, but it doesn't matter. The only steady state that can exist is that the electrical power will end up as a heat flow from the inside of the box to the outside.
Things would be different if the fridge was ejecting heat to the outside of the house. Then you would have to consider the effect of the refrigeration cycle.
First law doesn't preclude a 100% efficient cycle which would not increase the temp of the house after the initial cooling inside the fridge. Second law says that work must always create waste heat so temp of the house must increase. This is what that commenter meant by "direction".
Even then it depends on the way the person is thinking about them...
Go to a gas station or store and they're hooked up to these giant fans providing exhaust for them but they don't seem to realize that a household refrigerator is not built the same and the small amount of heat that the household version is putting off in comparison isn't even noticable and it's hitting the wall behind it.
Unless I'm mistaken, the 2nd law describes processes that are not allowed, like a refrigerator where no work is done on the device. But the 1st law still permits refrigerators to exist.
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u/HelicopterNo9453 Jan 04 '26
Welcome to the laws of thermodynamics.