4 ms·

>you can get 4-5 times as much heat out [...] ..but why? The second law of thermodynamics says that the amount of energy won't change, it can only change form

>you can get 4-5 times as much heat out [...] ..but why? The second law of thermodynamics says that the amount of energy won't change, it can only change form, right? (Correct me if I'm wrong, I'm not sure). So the electricity should either remain electricity or turn into heat? I get that it might not happen at the place where we want it to. For instance, we don't want to be heating up the ground between the power plant and my house where the cable runs. And I also get that turning heat into electricity (as it happens at the power plant) might not be efficient. But I still feel that it should perform better than running a pipe with hot water which seems more likely to leak heat into the ground along the way.

semi-extrinsic 8y ago
>>you can get 4-5 times as much heat out [...] > ..but why? Because you are literally pumping heat from outdoors to indoors. You are reducing the energy of the outdoor air and increasing the energy of the indoor air. The electric energy spent is used to drive a motor that is pumping a fluid round in a loop. The pump is placed where you go from outdoors to indoors. Opposite the pump in the loop, you have a pressure reduction valve, and together these give you a higher fluid pressure on the indoor side, say 40 bar vs 20 bar. The trick is that this pressure difference means that the low pressure fluid is also cold, so it can be heated by the outside air, and the high pressure fluid is warm, so it can release heat to then indoor air. The thing about running hot water (e.g. district heating) is because you use heat that is literally free. E.g. if you have a waste incineration plant burning all the garbage, that's a lot of free heat. Or if you have a big data centre, lots of waste heat. Let's use it! In systems like the OP post, the water acts as both energy storage and a convenient way to distribute heat. No DC/AC inverter, etc.

semi-extrinsic 8y ago

>>you can get 4-5 times as much heat out [...] > ..but why? Because you are literally pumping heat from outdoors to indoors. You are reducing the energy of the outdoor air and increasing the energy of the indoor air. The electric energy spent is used to drive a motor that is pumping a fluid round in a loop. The pump is placed where you go from outdoors to indoors. Opposite the pump in the loop, you have a pressure reduction valve, and together these give you a higher fluid pressure on the indoor side, say 40 bar vs 20 bar. The trick is that this pressure difference means that the low pressure fluid is also cold, so it can be heated by the outside air, and the high pressure fluid is warm, so it can release heat to then indoor air. The thing about running hot water (e.g. district heating) is because you use heat that is literally free. E.g. if you have a waste incineration plant burning all the garbage, that's a lot of free heat. Or if you have a big data centre, lots of waste heat. Let's use it! In systems like the OP post, the water acts as both energy storage and a convenient way to distribute heat. No DC/AC inverter, etc.