A visual way to explain banging pipes

Steve_175

At least in the case of standing water in the horizontal pipes. A dramatic visual of steam collapse.



<a href="http://boingboing.net/2014/02/03/imploding-soda-can-experiment.html">http://boingboing.net/2014/02/03/imploding-soda-can-experiment.html</a>

ttekushan_3

Steel drums (not the instrument)

Coincidentally, I was looking up "crushing steel drum with steam vacuum" videos over the weekend and saw these kinds of illustrations too. Slow-motion certainly shows with startling clarity at least one cause of water hammer.



But I was looking at the videos from the standpoint of steam's natural tendency for self-(re)distribution, extremely high thermal transfer efficiency at the radiator/fan coil and to illustrate the distributive power carried with the steam particularly where large temperature differentials exist. Powerful vacuum that occurs at the moment of the steam releasing latent heat and collapse into water is the mirror image of a force created within a steam boiler, a force that is *never* taken into account when measuring efficiency.



I'm going out on a limb to say that the measures of heating boiler efficiencies assume water at 212F or 215F or whatever and ignore a powerful dynamic that is occurring systemically with the phase change. It should be well known that heat is not the same thing as temperature, and that logic extends to the whole idea of condensing products of combustion. That simplification model works in water boiler world, but in steam world, the work of distribution is a primary characteristic of the medium itself. All other things being equal, steam will condense more in cooler environments than warm ones-- all without sensors, computers or any other active devices. The misunderstanding of these dynamics elicit the erroneous statements that "steam heat is difficult to control" and "steam boilers are less efficient and therefore steam heating systems are inefficient." Usually, it's a self fulfilling prophecy out in the field.



Crushing cans and drums illustrate the forces that should be considered when looking at system efficiencies. Further out on that limb, I'm going to say that a steam heating system that recognizes and utilizes this force will operate efficiently enough to warrant "handicap points" in the measure of boiler efficiency.



And fully off that limb, assuming full boiler modulation, that number should be as high as 10 percentage points.



Whew. I feel much better now.



Thanks for posting this!

Jamie Hall

It would be very nice indeed

if someone would award "efficiency points" to steam systems!  Provided they are working reasonably well in terms of nonsense such as pitch, reasonably dry (albeit saturated) steam, proper traps and the like, they are astonishingly energy efficient.



And they do self balance to an amazing degree -- I can demonstrate that on the system which I care for in a very "hands on" sort of way: there is but one thermostat, but the various rooms have varying heat loads depending on wind, solar gain, and so on -- and yet the various rooms stay remarkably constant in temperature.  A room is a little cool and losing heat faster?  Presto -- more steam condenses in the slightly cooler radiator, and more heat gets into the room, and the room temperature holds up.  And so on...



Trouble is, of course, it's hard to measure that sort of thing, so I don't suppose the bureaucrats and boffins in their labs will ever get around to it.  They ignore all sorts of parasitic losses, too...  sigh...