N. T. wrote:
>>> I think it can be a matter of time a refrigeration unit would take
>>> waste heat and even would freeze the output.
>>> The collected heat would drive a small steam turbine.
>>
>> You can't get power from waste heat and then "freeze the output".
>> You can derive power from the difference in temperature of the
>> exhaust and ambient. Doing so does cool the exhaust. However, it
>> can't cool it (in aggregate) below ambient without additional power
>> input. The point was to use the waste heat as power, so he obviously
>> doesn't plan to use additional power and it would defeat the purpose
>> anyway.
>
> "he obviously doesn't plan to use additional power" - "Telepathy" test
> failed, sorry.  A heavy truck moving downhill would cool its exhaust
> (and ambient air as well) to accumulate the thermal energy. The
> accumulated energy would boost the truck uphill.

Your original statement was only about using "waste heat" from the exhaust.
it seemed the point was to put this free power to use.  That by itself make=
s
sense, although you can't use that power to cause a net reduction in the
overall heat transferred from the vehicle to the environment.  You can make
something colder than ambient, but something else will end up getting hotte=
r
and in the steady state transferring the same total heat flow to the
environment.

Adding more power to this system from the engine would defeat the purpose,
so this would be a stupid idea and I was giving you the benefit of the doub=
t
that you therefore didn't mean that.  The extra power output of the engine
causes it to make even more waste heat.  You can't use a heat engine to coo=
l
its total output.  You'll only loose by trying since the heat engine isn't
perfectly efficient.

This is the first you said anything about going down a hill, potential
energy of the car, or not steady state conditions.  You really need to be
more clear what you're saying if you don't want people to misunderstand and
perceive you as stupid.

Apparently you are now saying that when going down a hill you run a heat
engine in reverse.  This heat engine uses the exhaust of the engine (So the
engine is still apparently on when going down a hill?  A bigger win would b=
e
to shut if off during that time) to store heat someplace in a hot and
possibly a cold reservoir.  Once the car needs to be pushed forward again, =
a
heat engine use the reservoir(s) to produce mechanical power to assist the
engine.

If that's what you're really saying then:

1 - You were VERY unclear originally at best.  More likely you didn't
    think this out well and this last wrinkle is just a response to
    getting caught and a failed attempt to save face.

2 - It's not clear you understand heat engines and what Carnot had to
    say.

3 - It still doesn't sound like a very good idea.  At reasonable
    temperatures you could expect for such a system in a car, the
    efficiencies will be pretty bad.  The mechanical systems for
    storing and retrieving sufficient power to be meaningful would
    also be rather large and heavy, again not well suited to a
    vehicle.

4 - This now has little to do with harnessing waste heat from the
    engine, which is what you were originally talking about.


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