On 02/08/2011 03:43 PM, Harry Veeder wrote: > stephen, the steam does absorb more energy, but this manifests as a > faster flow of steam rather than as a temperature increase.
No. Remember, PV = nRT for steam, just like any reasonable gas. That means, V = nRT/P If the steam flow accelerates with no change in pressure, and the diameter of the pipe is uniform, then its volume must be increasing as it moves along the pipe -- the steam is "spreading out" in the pipe. If its volume is increasing while pressure is constant, and nobody's adding more water vapor (so moles per second coming out the end of the pipe is constant), then its temperature must be increasing. And note -- the number of moles per second, n/time, is fixed by the constant displacement pump. QED. ------------------------------------------------------------------------ Incidentally, what happens if we turn up the pump rate just a little? Either (a) the thing starts spewing water, because the water no longer boils, or (b) the power level increases. Similarly, what happens if we turn *down* the water pump rate just a little? If the temperature doesn't suddenly start taking off, then the power level must have dropped. If the results of the test didn't depend, very critically, on the exact rate at which the pump was running, what can we conclude? Whoa, nelly! The power output is controlled by the water pump!
