Half a croissant, on a plate, with a sign in front of it saying '50c'
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Thermosiphon Central Heating

Reduce complexity, gain gurgling noises
  [vote for,

The standard drip coffee maker is a remarkable machine. Perhaps the most remarkable thing is the lack of remarkable things within. As machines, they seem durable at a level not attained by much else, especially consumer products that handle water. We have 4 dead examples in a cupboard here at work. They're not actually dead, someone just dropped the glass carafe. The local diner has an example from the late '60s that as far as I can tell has been in continuous 24Hr operation since it was bought.

The key lies in simplicity. The business end is a heated tube in the base. Cold water is fed to this from a tank and when the temperature rises above boiling point the steamy-water mix expands and is forced up to the coffee basket. This water is replaced by more from the tank, usually via the only moving part: a one-way valve.

Central heating systems, the type with water pipes and radiators, are a lot like coffee machines. They have a gas boiler on the ground floor/basement that heats water, this is then electrically pumped to the radiators. Sadly the durability isn't in the same league as coffee makers. Their reliability is also lower, since they rely on a gas supply AND an electrical supply to function. Should electricity be unavailable or the pump malfunctioning, you might freeze to death despite a plentiful supply of fuel. This would be embarrassing.

To prevent such embarrassment, I recommend a coffee- maker inspired pumping mechanism. The gas boiler heats water which is ejected up to the top of the radiator in the highest room. Here it fills the radiator until it overflows down the return pipe to the radiators on lower floors and ultimately the main tank. Flow can be regulated by manual and thermostatic valves as normal. To simplify the system further, the one-way valve should be eliminated. To do this, the holding tank and/or heating coil should be designed as a fluid inerter <link>. When the boiling water rapidly expands, the supply-side inerter will dramatically bias the pumping in the desired direction, a Tesla valve could also be added for the cool factor, depending on how cool you find inerters or Tesla valves.

To dramatically increase the effectiveness of the system, water can be replaced with mercury. Radiators operating at ~350C can be smaller and mercury has excellent inertance and antimicrobial characteristics.

bs0u0155, Mar 04 2019

Fluid inerter https://scarbsf1.wo...t-gp-fluid-inerter/
[bs0u0155, Mar 04 2019]

Capacitor fluid equivalent http://amasci.com/emotor/cap1.html
Mentioned in my anno. From [wbeaty] [notexactly, Mar 08 2019]


       Hmm. I'm not convinced that I'd enjoy the gurgling noises.   

       A mercury-loop system would be interesting, but I don't think you'd be able to use soldered joints, and I'm not sure how well push-fit would stand up to 350°C, so you'd be lumbered with compression fittings.
MaxwellBuchanan, Mar 04 2019

       //lumbered with compression fittings//   

       Small leaks aren't a major issue. Mercury will find its own way back down to the basement. In fact, there's no real need for the return piping at all. Just try and make sure any aluminum belongings are kept out of the larger streams.
bs0u0155, Mar 04 2019

       And... cue [8th] suggesting NaK.
MaxwellBuchanan, Mar 04 2019

       I think I would be interested to visit a house with radiators at -350°C
pocmloc, Mar 04 2019

       I think a lot of physicists would too.   

       I'm not sure I'm understanding how the inerter concept applies here, though. It appears to me to be just an inductor for liquids. Are you just putting it behind the boiler, as a low-pass filter to direct the expansion forward?
notexactly, Mar 07 2019

       //Are you just putting it behind the boiler, as a low-pass filter to direct the expansion forward?//   

       Exactly that. It's performing the function of the valve without any of that nasty wearing out business.   

       //It appears to me to be just an inductor for liquids//   

       I'm not sure, I'm slightly out of my depth when it comes to liquids. I arrived at the inerter via its use in F1 suspension systems. The original wasn't fluid, it was mechanical. Suspension travel was used to spin up a flywheel. It was particularly good at smoothing oscillations as it resists acceleration.   

       I followed the concept to a guy named Malcolm Smith at Cambridge. His explanation draws parallels between dampers and resistors, which I get. However, he equates springs with inductors and inerters with capacitors. I'm not comfortable with those, possibly because I don't understand. To me, a spring will not smooth oscillations while an inductor does, and an inductor will not store force like a spring. The inerter specifically resists CHANGE in input, storing that energy in another form.   

       It's fascinating, I thought all the mechanical stuff was done, we've been messing with wheels and cogs and levers etc for centuries, electronics for a few minutes by comparison. Is there an electronic equivalent of the self- closing valve in a ram pump?
bs0u0155, Mar 07 2019

       Diode or perhaps a transformer.
RayfordSteele, Mar 08 2019

       // However, he equates springs with inductors and inerters with capacitors. I'm not comfortable with those //   

       Me neither. When I use a hydraulic analogy to explain electricity (which is not that often) I typically think of a paddle wheel/vane pump thing connected to a flywheel as the equivalent for an inductor. And a capacitor becomes a rubber membrane with water connected on both sides [link]*, which is a kind of spring.   

       *That is just to be equivalent to an electrical capacitor; in real hydraulics you can also have a membrane or spring-loaded piston that's open to the environment on the other side, which is, I guess, equivalent to a capacitor with the other side grounded.   

       // Is there an electronic equivalent of the self- closing valve in a ram pump? //   

       I often describe hydraulic rams as boost converters for water, though the operation is not exactly equivalent.
notexactly, Mar 08 2019


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