Re: Quasiturbine - Over unity air motor ?

From: Saint-Hilaire (saint-hilaire_at_promci.qc.ca)
Date: 11/02/04 

Date: Tue, 2 Nov 2004 07:26:29 -0500

"Saint-Hilaire" <saint-hilaire@promci.qc.ca> wrote in message
news:B4ahd.79443$CT6.46403@sam.nntpserver.com...
> Quasiturbine - Over unity air motor ?
>
> Bonjour,
>
> I am not sure I did express myself sufficiently
> on efficiency in a recent post about the
> "Quasiturbine and the Air Car"...
> (see copy of the post below).
>
> What about a system extracting some net energy
> from ambient air temperature ?
> Not obvious of course, but possible ?
> ...

Bonjour,

Within a compressor in adiabatic process,
pressure increases for 2 reasons :
because of volume reduction and because of temperature increase.
Since the temperature is keep constant in isothermal process,
the pressure does not increase as much,
and the work done by the compressor on the gas is much less.
Said otherwise, the total amount of heat continuously removed
during the isothermal compression is less than
the heat accumulated at the end of an adiabatic compression
(this is the reason of the big "IF" in my previous poste).
Otherwise, the dilama would have been possible...

An other important difference is that
while adiabatic compression
produces valuable high temperature grade heat
suitable for Stirling recovery
(comming from extra compressor work),
isothermal compression produces worthless low grade heat
unfit for any heat recovery.

Consequently, it is not possible to extract mechanical energy
from ambient heat, conforme to Carnot principle
that 2 differents temperature sinks (heat flow)
are needed to do so !
However, both compression-relaxation cycles,
either isothermal (continuous instantanious heat removal)
or adiabatic (assuming no heat lost)
are equaly highly reversible.

Furthermore, if someone leaves you the choice between say,
a 100 degrees delta T over the ambient temperature
and the same 100 degrees delta T under the ambient temperature,
which one would you prefered in term of
mechanical energy conversion efficiency ?
Not only Carnot tell us the limit of thermal
to mechanical efficiency is proportionnal to delta T,
but he also state that for a given delta T,
this conversion efficiency
decreases with increase of the temperature zone.
This is why liquid nitrogen evaporation and thermalisation
to drive an air motor can provide higher conversion efficiency
than higher temperature large delta T of hot steam .

J'espère que vous avez apprécié la discussion...

Gilles
www.quasiturbine.com

Relevant Pages

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