On Apr 21, 7:18*pm, Tom Anderson wrote:
On Thu, 21 Apr 2011, Capt. Deltic wrote:
On 21 Apr, 09:58, wrote:
On Thu, 21 Apr 2011 09:33:41 +0100

Graeme Wall wrote:
Pedantically they have motors, not engines. �The latter being those
nasty infernal combustion thingies. �Motors run on nice clean electrickery.

Tell that to Arthur Daley!

To be even more pedantic, an engine generates power, while a motor
consumes power.

What? *What*?

'Generates' power? 'Consumes' power? Has that small matter called the
first law of thermodynamics passed you by?

I assume Uncle Roger means "shaft power" as used in the context of the
second law applied to a control volume (ie work rather than heat).

All any of these devices do is convert energy from one form to another.
They might be coupled to devices capable of storing energy. But whenever
they are in operation, the flows of energy in and out are equal; not all
of the energy coming out will be useful, but it's there. A flow of energy
is power, and so all these devices do is convert power from one form to
another.

An electric motor converts electrical power to mechanical power. An
internal combustion engine converts chemical power - a flow of constant
mass in which the output has a lower chemical potential than the input -
into mechanical power. An external combustion engine - if you were
inclined to exclude the boiler - converts pressure power (which can't be
the right name - aerostatic power?) into mechanical power. They're all
just power converters.

Calling one an engine and one a motor is a matter of convention. It's
preposterous to ascribe a fundamental meaning to the distinction.

The distinction is related to the second law. A motor converts "work"
to other "work" while an engine converts heat to work (and some left
over heat).

Robin

On Fri, 22 Apr 2011 03:30:17 -0700 (PDT)
bob wrote:
The distinction is related to the second law. A motor converts "work"
to other "work" while an engine converts heat to work (and some left
over heat).

Internal combustion engines don't convert heat to work. The work is done
by the pressure of the gas from the chemical reaction. Heat is a useless
byproduct of this reaction that has to be got rid of.

B2003

On Apr 22, 3:53*pm, wrote:

Internal combustion engines don't convert heat to work. The work is done
by the pressure of the gas from the chemical reaction. Heat is a useless
byproduct of this reaction that has to be got rid of.

I suggest you study thermodynamics andn especially the Otto Cycle and
the Diesel Cycle.

--
Nick

On Fri, 22 Apr 2011 08:09:23 -0700 (PDT)
D7666 wrote:
On Apr 22, 3:53=A0pm, wrote:

Internal combustion engines don't convert heat to work. The work is done
by the pressure of the gas from the chemical reaction. Heat is a useless
byproduct of this reaction that has to be got rid of.

I suggest you study thermodynamics andn especially the Otto Cycle and
the Diesel Cycle.

I would suggest you basic physics. A small volume of liquid is converted
into a large volume of gas in a confined space. The fact that heat is
also generated is irrelevant other than the chemical reaction requires it to
be self sustaining. There are plenty of other chemicals you could react in
liquid form that produce heat but no gas - try squirting them in your cylinders
and see how well the engine works.

B2003

On Apr 22, 4:27*pm, wrote:

I suggest you study thermodynamics andn especially the Otto Cycle and
the Diesel Cycle.

I would suggest you basic physics.


I have. I am an engineer. Thermodynamics is fundamental. I suggest you
study it before you bury yourself deeper.

There is waste heat yes, but it is heat that does the work. Heat does
all the useful work, the waste heat is that which can't be used.

--
Nick

On Fri, 22 Apr 2011 09:21:57 -0700, D7666 wrote:

On Apr 22, 4:27Â*pm, wrote:

I suggest you study thermodynamics andn especially the Otto Cycle and
the Diesel Cycle.

I would suggest you basic physics.


I have. I am an engineer. Thermodynamics is fundamental. I suggest you
study it before you bury yourself deeper.

There is waste heat yes, but it is heat that does the work. Heat does
all the useful work, the waste heat is that which can't be used.

http://www.iankitching.me.uk/humour/hippo/entropy.html

Refers.

--
From the Model M of Andy Breen, speaking only for himself.

On Apr 22, 5:28*pm, Andy Breen wrote:


http://www.iankitching.me.uk/humour/hippo/entropy.html

Refers.

)

Alas that will be lost on the very object who could do with it the
most.

--
Nick

On Fri, 22 Apr 2011 08:09:23 -0700, D7666 wrote:

On Apr 22, 3:53Â*pm, wrote:

Internal combustion engines don't convert heat to work. The work is
done by the pressure of the gas from the chemical reaction. Heat is a
useless byproduct of this reaction that has to be got rid of.

I suggest you study thermodynamics andn especially the Otto Cycle and
the Diesel Cycle.

There's a reason they're all collectively known as "heat engines".

And to state that "the work is done by the pressure of the gas" and then
go on to say that "Heat is a useless byproduct" suggests that the very
concept of equations of state (starting with PV = NkT) has passed someone
by.

--
From the Model M of Andy Breen, speaking only for himself.

On Fri, 22 Apr 2011 16:06:12 +0000 (UTC)
Andy Breen wrote:
I suggest you study thermodynamics andn especially the Otto Cycle and
the Diesel Cycle.

There's a reason they're all collectively known as "heat engines".

And to state that "the work is done by the pressure of the gas" and then
go on to say that "Heat is a useless byproduct" suggests that the very
concept of equations of state (starting with PV = NkT) has passed someone
by.

It IS done by the gas pressure. The energy is the bond energy in the fuel -
its not stored in the fuel as heat FFS. The heat will increase the pressure
somewhat but its effect is minimal. If you could somehow reduce the
temperature to ambient after the reaction had finished the gas would still be
under pressure and would still push the piston down.

If you two seriously think the heating of the gas is solely responsible
for the work done on a piston then you might want to explain why we're not
using hot air balloons to lauch the space shuttle.

B2003

On Apr 22, 5:42*pm, wrote:

If you two seriously think the heating of the gas is solely responsible
for the work done on a piston

You have already been told - PV=NKT

And we never said what you just said we said.


--
Nick