"It's like a party -- sometimes you have to go outside to cool down.  Then
you come back in and heat up again."

...so, being Fryedaye ..... PV = Party Vanimal?

Bob Stevens

http://groups.msn.com/BobsPhotoShare

----- Original Message -----
From: "Bill Marshall" <Willolyn99@AOL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, August 08, 2003 6:41 PM
Subject: Re: repost - basic a/c hose connection question.

> So if we look at the equation
>
> PV=nrT
>
> Where P is the pressure, V is the volume, nr is basically the amount of
> stuff
> in the gas, and T is temperature, we find that there is an equivalence, or
> proportionality, between PV and T:
>
> PV~T
>
> So, if one of these variables remains the same, then the other 2 will
> change,
> and in a way that follows this ratio.  So, for example, if the pressure
> increases and the volume does not, the the temperature will increase:
>
> P(x)V~T(x)
>
> Not necessarily a direct ratio, but they will change in a similar way.
> So,
> at the compressor, the pressure is increased by the pump.  The volume
> remains
> constant, so the temperature goes up.  That explains the heat on the
> DIScharge
> side of the compressor.  This hot, compressed gas goes to the condensor in
> the
> front of the van.  Here, the air in the atmosphere cools the compressed
> freon
> through a convective current.  Now, we have subtracted heat from our PV~T
> system, yet we are still pressurized, so we will find that the volume has
> been
> reduced -- the gas becomes a liquid.  The phase change is often
> accompanied by a
> big change in energy to the system.
>
> Still under high pressure, the liquid is sent to the evaporator in the
> rear
> of the van.  Through a small orifice, the pressure is allowed to escape.
> At
> this point, the reducton in pressure causes the liquid freon to evaporate,
> increasing in volume.  This phase change causes the freon to cool
> considerably --
> the pressure loss is reflected in the temperature loss.  The cooled freon
> gas
> is sent through the evaporator coils, and exchanges heat with the air on
> the
> inside of the van.  This heat is brought to the compressor, to be
> compressed and
> sent to the condensor in the front again.
>
> Continuous cycle -- the heat is grabbed at the evaporator, is collected at
> the compressor, and is sent to the condensor to have the heat released to
> the
> atmosphere.
>
> Easy.  It's all in the motions of molecules.  It's like a party --
> sometimes
> you have to go outside to cool down.  Then you come back in and heat up
> again.
>
> Bill Marshall
> '85 GL Tiico "Pandora"
> Aurora, IL
>