Compression ratio and compression test readings.

[Eric Fahlgren]

Greg Hermann wrote:

> Yep. Where .283 = (k-1)/k, "k" for air =1.395 = the ratio of Cp/Cv . Cp
> =specific heat at constant pressure, Cv =specific heat at constant volume.
> "k"varies with the molecular weight of a gas.

Greg,

I believe k == gamma varies with the molecular structure of the
gas, not it's molecular weight.

An interesting (?) read on how gasses store energy can be found
in the Nuclear Weapons FAQ (how far OT are we getting? :).

   http://www.fas.org/nuke/hew/Nwfaq/Nfaq3.html

Scan down to section 3.1.6 and you can see how gamma arises from
the degrees of freedom available in typical monatomic and diatomic
gasses...

Diatomic gasses (N2, O2) apparently have a total of seven degrees
of freedom, but only five are "usable" at STP, hence gamma = 7/5
for a pure N2-O2 mix.  Of course real air is "contaminated" with
non-diatomic junk, like CO2, so the 1.395 is an empirically derived
value accounting for these other gasses.  Groovy, eh?

Eric
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org