Peltier heat pump for waterless condenser

[guerrila distilla]

just been looking through some of the sites given in the reputable dealers thread and i came across this one ( thanks to snuffy) :-

http://www.sciplus.com/category.cfm/subsection/16" onclick="window.open(this.href);return false;" rel="nofollow

Check out the peltier heat pump, apparently it is a sort of solid state heat exchanger that can cool itself below ambient temperature on one face, whilst releasing heat on the other. this one also runs on 12v. maybe it would be of some use to someone who wanted to design a waterless condenser. at $20 a piece, that's a pretty good price

does anyone know anything about these as it's the first time i've seen them?. also i'm not too electrically minded, so they may be completely useless.

[glassman]

they realy do work. their small..like 1" sq or there about. i've seen them used in small cooler for drinks...like you would put between the seats in your car. they do generate a bit of heat on the opposite side. fun to play with. gman

[snuffy]

They also work backwards: put a temperature differential across them and they generate electricity.

http://www.caframo.com/ecofans.htm" onclick="window.open(this.href);return false;" rel="nofollow

For cooling, all you need to drive them is a DC supply. A big one might draw 8A @ 12VDC. You could pull these parts from a junked computer.

They work best with a fan on the hot side heat sink. Hint: MPJA.com for one stop shopping

[HookLine]

Yeah, I've seen them before and played with them. Thermo-electric cooling. Pretty interesting devices. Used in some lab gear. Couple guys I worked with built a single beer cooler from them, just to see if it could be done (it can). Very inefficient though. Water is much cheaper, easier and more effective for our purposes.

[Barney Fife]

As to a waterless condenser, I've been thinking that we could use a small gas fridge's innards, and make it work for us. For those who don't know how a gas fridge works, see here: http://home.howstuffworks.com/framed.ht ... ption.html and here "http://www.rvmobile.com/TECH/TROUBLE/coolunit.htm.

An RV(travel trailer) fridge can be very small. Since so many distillers use propane to heat the boiler, some of that wasted flame could be cleverly diverted to run the condenser at the same time, making better use of the flame. These can also be operated electrically, on 12 or 110 volts. RV fridges usually outlast the RV(there are zero moving parts), and they sell quite cheaply, especially the older, smaller ones.

Think outside the box!

[seravitae]

dont use peltiers for this job. more trouble than its worth. the heat load you are trying to remove is huge, peltiers are designed to make small areas very cold.. use a fishtank pump, some tubing and a car oil/motorbike radiator (from the wreckers, cheap).

on another note, it'd be interesting to make a stirling engine based cooler, using the condensor as the hot side, and attaching the crankshaft to a fan/pump on your radiator - that way the condensor temperature self regulates. plus it looks danm awesome.

[guerrila distilla]

a stirling engine, now that could be an interesting project. given the heat given off and wasted, a fairly powerful stirling engine could be run off the top of a boiler. that's an ideal free heat source for this type of project. i looked into it and found that stirling engines have been made up to 5 hp (about 3.5kw), allthough these engines used a combustible fuel to provide the power. i wonder if it would be possible to build one powerful enough to run a water pump hooked up to bucket of ice water. i'd be interested in trying this out just as an engineering exercise.

[manu de hanoi]

what about that :
http://en.wikipedia.org/wiki/Heat_pipe" onclick="window.open(this.href);return false;" rel="nofollow

anyone ever had some xp with that ?

[decoy]

heat pipes are easy to make...

if you get a 1+ ft length of 1/2 to 3/4 copper pipe, it helps to rough up the inside of the tube with some coarse sandpaper this will help retain alcohol as it runs back down the walls of the tube while in operation.
now seal the bottom compleetly and at the top of the pipe end weld or solder a thin 1/8 copper pipe or similar like in refrigeration,

heat pipe.jpg (11.17 KiB) Viewed 4677 times

place approx 3ml of 95%+ alcohol inside the tube
heat the tube and let the alcohol boil so vapour escapes thru the smal tube for 30 od sec.
the idea is the when alcohol in the tube boils and turns to vapour it will expel or replace the air in there.
now crimp the smal tube tight, eaven fold it over, and place a dolop of superglue or hotmelt on the end.
you want most of the alcohol to remain in the tube
as it cools a vacume will form inside the tube, the glue will further stop air being sucked back in.
wela, you now have a heat pipe.

if you have a spot welder you can spot weld the end shut.
or you can hit the end with a tig.

this can be used in any angle as long as its not horizontal.

you place the bottom of the tube in the hot surface and the end of the tube higher up

as the alcohol heats up it evaporates, and because its in a vacume
1 it will evaporate at a lower temperature
2 the vapor which contains the heat will travel / fill to the end of the tube were you can have a heatsink or fan cooling it.

the liquid will then condense and run back down to the bottom, creating a cycle.

the tube can be 50M long you could use it as a condenser running the heat out side the house... etc
as long as the liquid can flow back to the bottom after it condenses.

for longer tubes you will need more liquid alcohol added.
the idea is that if you were to boil the tube tube at the hottest temperature it will be exposed at that it will not rupture/explode from over presure while at the same time you have enough liquid to turn into gas/vapour to reach the end of the tube and be able to condense and return.
if you aonly heat one end of the tube and the other is in a cooler area it will never rupture as it will always cool and condense.

you can use liquids or gases that boil at lower temperatures to increase performance.

eg. ammonia.\, this is how early refrigerators worked..

cheers..

[manu de hanoi]

thanks for that precious post Decoy.

[seravitae]

decoy, not a bad idea. though spot welding in a field of gaseous ethanol sounds like a bad idea.

You can make a good heat pipe using butane (lighter refills) too, using the same system.

Mind you, this does not actually solve your heating problem, it just moves it.

[decoy]

once you have crimped the end there is no alcohol there, and if there was it would just catch fire..

as far as what is in the tube you need air in order for it to burn let alone explode..