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Comment: Re:Not so fast, Thermodynamic laws are pesky thing (Score 1) 150

by newcastlejon (#46778809) Attached to: 'Thermoelectrics' Could One Day Power Cars

why is waste heat "garbage"?

Because it's low temperature and high entropy.

...that we are currently actively cooling parts and attaching heat sinks and radiators for merely decorative purposes?

No, we do it because the devices need to be cooled and it's not worth the expense of slapping a thermocouple on them for the pitiful return one would get.

and if waste heat is an actual phenomenon... why NOT harvest energy from it?

See point the first.

complexity is low with no moving parts.

We've been making ICEs for a long time; we know how to make them reliable. Just because an alternative is presented that's solid state doesn't mean we should automatically jump on it.

price is currently high but as with most things, that can come down with research.

Then report a story that says "powers car" instead of "could one day power cars"

so waste heat exists. power can be harvested.

Never in dispute, but that doesn't mean it's worth doing. Look at it this way, would you go to the trouble of putting a heat exchanger between your bathroom plughole and the inlet for your heating system? There's waste heat there too, but not enough to justify the expense you'd be in for. That's to say nothing of the fact that it would be immensely more efficient than a theromelectric doodad.

i don't see what the point of your tirade is.

I'm guessing here, but maybe it's because the parent is frustrated that you don't appear to see that there's a reason it's called waste heat. Seriously, a large sink sitting slighty above ambient temperature may hold quite a lot of energy, but it's not practical to try and extract any work from it. As an exercise, read up a little on two things: Carnot efficiency, which has been covered nicely by posts above, and low grade heat, which is only really useful for heating something colder, not anything that needs a temperature differential (i.e. any heat engine, solid state or otherwise.)

Comment: Re:power cars? technically no (Score 1) 150

by newcastlejon (#46778057) Attached to: 'Thermoelectrics' Could One Day Power Cars

Anybody who actually has some grasp of the matter want to chime in on where and why you would use thermoelectrics (and how efficient they would have to be) rather than simple insulation or one of the various waste-heat-recovery systems that transfer some amount of the heat remaing in outgoing exhaust gases into incoming working fluids?

In IC engines you want the intake air to be cold so the density is higher (more oxygen); you may have noticed that cars with turbo charges often have something called an intercooler for this reason (compressing the intake air heats it). If you're going to scavenge anything from the exhaust gases it will be low-grade heat (delta-T is smaller, moreso with an efficient engine). Using heat from exhaust to pre-heat the intake is more commonly done with gas or steam turbines, where you want to reduce the amount of heat you need to put into the working fluid at the "cold" side.

I expect that the reason thermoelectrics haven't seen much use in cars is because the benefit you get from using a low efficiency method with a low delta-T just doesn't justify the expense of adding them. I wouldn't be at all surprised if one could gain more by attaching a generator to a turbocharger.

In fairness though, TEs are good if you want something low-powered and simple, but it's not that unusual for a diesel engine to last longer than the car it's put into, so the issue of reliability - one of solid state's big plus points - is rendered moot to an extent. For my own two penneth worth, if they're going to use TE devices to provide power for accessories (you'd never get enough to actually "power" a car without massive efficiency improvements - stupid title) you might as well use the very efficient alternator* you already have attached to the engine.

*Essentially an AC generator with some rectifiers attached. You can get upwards of 75 amps @ 12V if you really want to.

Comment: Re:power cars? technically no (Score 1) 150

by newcastlejon (#46777847) Attached to: 'Thermoelectrics' Could One Day Power Cars

Probably not. Internal combustion only means that the combustion occurs inside the engine. Contrast this to a classic example of external combustion: a steam engine, where the fuel is burnt well away from where the work is produced. Jet engines are internal combustion; most stirlings are external.

One might have a good case for arguing that thermoelectric engines are neither IC nor EC, since it needn't be combustion that provides the heat.

Comment: Re:Firmware (Score 2) 394

by newcastlejon (#46569451) Attached to: Is the Tesla Model S Pedal Placement A Safety Hazard?

Hill starts are quite easy when you get the hang of them: keep one hand on the handbrake (parking brake), and bring the clutch up to the biting point until you feel the car struggle a little against the brake then slowly release the handbrake while you give it a little more throttle.

It's almost exactly the same as pulling away normally except you let the clutch bite a little more before you release the brake. Failing that, you find the owner of the other car and tell them what an inconsiderate tool they've been; either they move or you find yourself unconscious only to wake with the offending vehicle having mysteriously vanished.

Comment: Re: Redefine hunting. (Score 2) 397

by newcastlejon (#46566773) Attached to: Drone-Assisted Hunting To Be Illegal In Alaska

There's ample evidence for animal worship by palaeolithic humans. I was specifically thinking of the Celts, but it doesn't seem that far of a stretch for me to assume that humans in general would try to treat their prey well. Humane slaughter formed quite a large part of abrahamic religions still practiced today, but even the oldest branches of those don't stretch back quite as far as flint as far as I know.

If that's not good enough a citation then fine, you win. Now I'm curious how you can justify the ethics of bow hunting just for mere target practice in case civilisation somehow comes to an end. You might as well argue that soldiers should have to practice with longbows in case their guns all decide to fall apart at exactly the same moment.

Comment: Re: Redefine hunting. (Score 3, Insightful) 397

by newcastlejon (#46565441) Attached to: Drone-Assisted Hunting To Be Illegal In Alaska

There's reasons why people practice this form of hunting for a hundred thousand years.

Because they hadn't invented guns yet. Give a subsistence hunter a choice between a bow and a rifle with free ammo and see what they choose. Even back when people were hunting with bits of flint on the end of sticks they cared about reducing the suffering of what they killed; that's to say nothing of wanting a more reliable means to bring down one's next meal.

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