In Reply to: Overall volume & heat posted by Ken Kurtis on February 23, 2007 at 14:24:40:

HoloD is approximation of constant system volume is corrct: "The point you are missing is that storage tanks are huge and when an empty tank is hooked up to a storage tank and becomes one system the TOTAL volume is almost unchanged (because your tank is so much smaller than storage tanks)."

When a tank is hooked to a compressor the total system volume is that of the tank and the hose between the tank and compressor. This is essentially the tank volume and if you assume adiabtic compression and expansion (not strictly true) then you can approximate what happens with Boyle's law.

When you connect two tanks with a hose the total system volume is the sume of both tanks plus the hose. This HoloD's arssertion is correct. Again here you can approximate with Boyle's law, but you must use the total system volume.

See my explination below. Perhaps then you will understand why the tank cooled.