Well I spent an hour or so in the HVAC world and sure enough Jed was right. Apparently the standard for measuring air flow in a round duct involves checking wind speed in 18 locations along three separate axes, which is probably not practical when you are trying to assess air flow in a dynamic system. On the other hand I think it is safe to assume that the purveyors of natural gas have worked out a way to know precisely how much petroleum is flowing through their pipes. In the lung doctors office you can blow into a tube that will show precisely how much air your lungs are moving. So if there was a monetary reason to efficiently know how much air is moving through a system we would probably have a reliable means of doing so.
On Sun, Oct 12, 2014 at 4:19 PM, Jed Rothwell <[email protected] <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: > I have had wretched experiences trying to do air-flow calorimetery. It is > done by HVAC installers on a daily basis, so it does work, although I > gather it is imprecise. I know it is hard to do right. > > The hard parts are determining the flow rate of air, and finding the > temperature, which varies in the stream even when you go to great lengths > to mix the air. > > - Jed > >
