Comment by thenthenthen

9 hours ago

@3:10 “you need to consider 99.9% of the power is converted to heat” uhm that would be quite an efficient heater you designed there!

One could argue that it is 100% as every Watt that enters through the socket (not counting reactive energy) is going to become heat at some point in the very near future, including the air moved by fans, the photons emitted by the screen, etc etc.

Not really? The best heaters are heat pumps which can under typical operation reach 300-500% efficiency (COP). Technically they aren't converting the electricity into heat, but for arguments sake here about heaters we only care about electricity consumed to heat generated.

  • > Technically they aren't converting the electricity into heat

    In fact they are converting 100% of it, they are just also collecting and moving additional heat in the process.

Isn't that lower than a purely resistive heater?

  • Only if the resistive heater in question is DC or AC with reactive power compensation

    • A purely resistive heater, by definition, has no reactive component so there's no reactive power considerer.

      The 0.1% mentioned might be the light that the project produces.

      5 replies →

Every computer is just space heater with side effect of computations.

The same way every diesel engine is just oil stove with side effect of rotary motion. If the engine was in the back of the car you could totally put a pot on it and braise something.

  • My gaming laptop is surely 90% noise and heat (so heat?), but my m1 macbook… is less heat.. but still heat? From reading this thread everything will become heat, which sorta confuses me, but yeh i guess bitluni was nit talking about efficiency but more thermodynamically?!

  • A diesel engine is a very inefficient stove though, as only half (more or less, depending on the exact engine) of the energy is converted to heat, the leftover being mechanical energy.

I’m curious about what you’re thinking of, but for both electric heaters and computers, essentially 100% of the input energy is converted to heat one way or another.

What you may be thinking of is efficiency when the output is intended to be something other than heat. In those cases, efficiency is lost because a significant proportion of the input energy is converted to heat.

But if heat output is what you’re interested in, I’m happy to report that 100% is a perfectly achievable, in fact hard to avoid, number!

  • Where the heat goes is the problem I have with that rating. An electric resistive stove is 100% efficient at converting input electricity to heat, but an induction stovetop is far better, better even than gas, for cooking on.