Hi Theo,
I think I've got it!
Please disregard my last e-mail!
Paul
Smit, Theo wrote:
> Hi Paul,
> The amount of oxygen in the air (i.e. the mass of oxygen in a cubic
> foot, or any fixed volume) determines the amount of power that the
> engine can make and therefore the amount of waste heat generated. If the
> "air" has a higher or lower percentage than normal of oxygen, then the
> potential power output of the engine goes up and down accordingly, even
> though the air density hasn't changed. On the other hand, if the air
> itself is being compressed or expanded, thereby giving either a greater
> or lesser total mass per unit volume, then the power output of the
> engine will also go up and down in a corresponding fashion, even though
> the percentage oxygen as a function of the total weight of the volume of
> air hasn't changed.
> So if you cram more oxygen into a given volume of air, whether that is
> by increasing the total air mass or just by increasing the oxygen part,
> you will make more power and more heat, and if you reduce the oxygen
> content, you will make less power and less heat. The oxygen content by
> itself has little to do with the radiator cap function.
>
> The radiator cap is a pressure difference limiting valve, between the
> coolant on one side and the ambient air on the other. The radiator cap
> allows the coolant pressure to be up to XX PSI higher than the outside
> air pressure, and then it opens. So if the ambient air pressure
> (referenced to outer space) is 14.7 PSI and the cap is rated to 13 PSI,
> then it will limit the cooling system to 27.7 PSI absolute pressure. If
> the ambient air pressure is 12.5 PSI, then the cap will limit the
> cooling system to 25.5 PSI absolute pressure, and the boiling
> temperature of the coolant will be correspondingly reduced. The coolant
> boiling temperature depends on the absolute pressure, not the pressure
> relative to the ambient air.
>
> Best regards,
> Theo
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