On Tue, 22 Jul 2003 01:55:20 -0400 (EDT), Henry Spencer <[EMAIL PROTECTED]> wrote:
>The Joule-Thompson coefficient, which determines *how much* cooling you >get when a gas expands through an orifice, is not a constant, even for a >particular gas. In particular, it is a function of temperature. Normally >there is a temperature at which it changes sign, the Joule-Thompson >inversion temperature. Above that temperature, the gas gets hotter, not >cooler, when expanded through an orifice. > >(Note that expansion through an orifice is *not* the same as expansion >against a piston in a heat engine. Since the latter does work on the >piston, *it* always cools the gas, but the former is more complicated.) OK... What's the physical mechanism? Adiabatic cooling is straightforward: apply Boyle's Law. But why does passing through an orifice have any effect on gas temperature? Is it a sonic thing? -R -- Son: Dad, I have a question about women. Suppose I Dagwood: Apologize anyway. Son: Yeah, that's about what I figured Dagwood: It saves time _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
