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Acetone wet haystack engine

Grind hay and pour acetone through them.
  (+3, -1)
(+3, -1)
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The problem with burning things is they can get hot. The good thing about burning wet things is that they can only get as hot as the boiling point of water and once the water is gone you are no longer burning wet things.

The Acetone Wet Haystack Engine (AWHE) produces heat on the same principle as a wet haystack which is hot but <100C. As with other boilers heat is controlled by ingress of air, with care taken to not let air cool the wet haystack too much.

Pipes carrying acetone thru the boiler capitalize on the low boiling point of that miracle molecule, and capture energy with the phase change as with an air conditioner.

The AWHE is fueled by wet hay, dung, dung and wet hay, or any other finely minced celluosic product that might be handy.

bungston, Jan 28 2020

compost heater https://en.wikipedi...wiki/Compost_heater
[Loris, Jan 29 2020]


       <Considers relative merits of lecturing yet again on Sadi Carnot's theory of heat engines vs. the option of hitting [bungston] repeatedly and forecefully with a long, heavy length of timber/>   

       <Writes "DeltaE (T2 - T1)" on whiteboard/>   

       <Selects pickaxe helve, adopts purposeful look and manner/>
8th of 7, Jan 28 2020

       Why either/or?
MaxwellBuchanan, Jan 28 2020

       // Sadi Carnot's theory of heat engines//   

       But is it actually intended as an engine, or is it really acting a source of heat for a heat pump?
I know it has 'engine' in the title, but the body test talks about it being a boiler and producing heat.

       The latter is reasonable enough to have been done in some central heating and hot water systems, although not with acetone in the heat pipes, as far as I know.
Loris, Jan 29 2020

       It is in effect a "bottoming" cycle to recover low grade heat energy; it's a heat engine, not a heat pump, which are always energy-negative.   

       Since the Delta-T between the source and the sink is low, the yield in energetic terms will also be low. While it can be made to work on a theoretical basis, the value of the output in such systems rarely if ever justifies the capital and maintenance costs of the installation.   

       The requirement for a volatile working fluid like acetone (and there are cheaper and safer alternatives) reveals the inherent inefficiency. A Stirling engine on the "back end" would give a small amount of mechanical power, but the energy source itself is highly limiting.   

       A better cycle would be:   

       Burn the fuel in a conventional furnace, boil water in a closed-circuit turbine loop, use the mechanical energy directly or for electrical generation, and use the "waste" heat from the condensers to thoroughly dry and then pulverize the fuel charge to continue the cycle.   

       [-] bad thermodynamics.
8th of 7, Jan 29 2020

       //Acetone wet haystack engine// - the random Halfbakery idea name generator has been hard at work!
hippo, Jan 29 2020

       //Since the Delta-T between the source and the sink is low,//   

       If we replace the acetone with liquid nitrogen, the delta t improves dramatically! IN2, as everyone knows, is to all intents and purposes free. This is common sense. The source material is free. LN2 vessels are often stored in low-traffic areas of the building and the "it's been a hot week, I guess the boil-off can get out of hand" excuse is totally plausible.
bs0u0155, Jan 29 2020

       No, it doesn't. The energy used to recompress and reliquify the N2 makes it grossly inefficient.   

       Just wait there until we've finished beating on [bungston]. Do you want us to clean the blood, tissue and bone fragments off the pickaxe helve before we start on you, or do you just want to get it over and done with ?
8th of 7, Jan 29 2020

       //recompress and reliquify the N2 makes it grossly inefficient//   

       Not if you have a handy supply of liquid H2, and, I know, before you get there, the answer to the next question is liquid helium.
bs0u0155, Jan 29 2020

       How crude. Why not use a stable wormhole linked to intergalactic space as a cold load ?   

       <Eyes [bs]'s knees thoughtfully/>   

       Which side do you want your tutorial to start ? Left or right ?
8th of 7, Jan 29 2020

       //energy used to recompress....//   

       The difference between my system and say, oil or uranium is only time.
bs0u0155, Jan 29 2020

       Left, we think. Do you want a blindfold ?
8th of 7, Jan 29 2020


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