Re: nitrous in your car?

["Dave Aukerman" <aukdav@wcoil.com>]

Heating the bottle with a propane torch used to be the drag racers secret.
Only problem was if you gave it too much . . .boom.  Usually you lost more
than just a few digits.

Dave

-----Original Message-----
From: Robert Myers <rmyers@inetone.net>
To: Robert Wunderlich, DPM <Robert@Wunderlich.com>
Cc: Quattro list <quattro@audifans.com>
Date: Wednesday, September 29, 1999 9:58 PM
Subject: Re: nitrous in your car?


>At 07:39 PM 09/29/1999 -0500, you wrote:
>>There is a significant decrease in pressure between a full tank and a near
>>empty tank at the same temperature (which thereby leads to a significant
>>decrease in available HP).  Thus, the bottle heaters are designed to
>>compensate for the loss of volume as the tank gets empty, which keeps the
>>pressure closer to that of a full tank.
>>
>>Said another way:
>>
>>pv=nRT
>
>This is the applicable equation only after nearly all the liquid N2O has
>evaporated.  Before then the liquid's presence maintains nearly uniform
>pressure in the tank *assuming constant liquid temperature*.  Upon release
>of gaseous N2O more liquid will evaporate to replace the gas in the tank
>thus keeping pressure up.  It takes energy to convert the liquid into gas.
>That energy comes at the expense, initially, of the liquid (and tank) which
>will get colder as gas is released.  This cooling effect will reduce the
>equilibrium vapor pressure of the (now cooler) liquid and the pressure in
>the tank will tend to fall.  When there is much less liquid and gas is
>consumed at approximately the same rate the heat needed to drive the
>evaporative process is derived from a smaller and smaller mass of liquid
>and the chilling effect is incresed since the same amount of energy is
>being crawn from a decreasing mass of liquid in the same time period.
>Apparently these effects are compensated for by use of a heater to maintain
>the temperature at a more or less constant value.
>
>Once all the liquid has been evaporated then the PV=nRT equation applies.
>
>Note the assumption that the volume of the gas does not change is just a
>first approximation.  The volume of the liquid does slowly decrease and
>therefore then volume of the gas does slowly increase but as a first
>approximation it can be regarded as more or less constant since the tank
>doesn't change size appreciably.
>
>
>___
>   Bob
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