Author Topic: heat exchanger  (Read 2255 times)

vegoil

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heat exchanger
« on: October 17, 2018, 06:21:25 PM »
dose anyone know if this heat exchenger has been used on the exhaust on a Lister CS to heat water?
or if it can work?
OR is there sump-thing better?
please have a look on Ebay.

 160mm Exhaust Gas Heat Exchanger Flue Gas Heat Exchanger AWT-7/160-VA

John

saba

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Re: heat exchanger
« Reply #1 on: October 17, 2018, 08:55:54 PM »
Good answer from glort, the one you propose on ebay is for a woodstove not really suitable. Some people use swimming pool heaters if you can get one cheap give it a try.

AT the moment i am using a old oil cooler with brass pipes inside, it works super and condensates the exhaust gasses. Only thing it clogs up with soot. And it's a ..... to clean.

Next plan, if I ever have time, is to install the inside of a condensing natural gas central heating boiler, it has a drain for the condens and it's sort of made for it.

Greetings Bernhard

vegoil

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Re: heat exchanger
« Reply #2 on: October 17, 2018, 10:20:39 PM »
thanks for the answers.

 I have already looked at pool HE plus a lot more on the internet
I have also thought about a pipe in a pipe. the exhaust I have is 73mm OD and I have a pipe that could go over it at 103mm ID that would give a gap of 15mm water jacket I have room to make one up to 1 meter long and another 600mm long. maybe weld spiral  inside the water jacket. ( just thinking out loud)

the cost of the build would be minimal  as I have all the parts needed and its all stainless pipe

I also have the just the core of a bronze oil cooler 850mm long 200 round (very very heavy) plus I had been thinking ahead about how to clean the d***d thing

what do you think?

John

BruceM

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Re: heat exchanger
« Reply #3 on: October 17, 2018, 11:32:43 PM »
As I recall, Mobile Bob came up with a design for a diesel exhaust HE that he claimed was easy cleaning/maintenance. I'd suggest going over to the microcogen forum an asking for his help.

Exhaust HE is a lot like elaborate gray water systems-  everyone abandons them in time because of all the labor in cleaning them.  So a design that was oriented around ease of cleaning from the get go makes a lot of sense. 

I never followed this area closely as my Listeroid is WAY too far away to be useful for heating, nor do I run it for long enough periods in the winter.  You are at likely only collecting about 1500 watts of heat from a 6/1 running full load with 2400 watts on the generator. Unless the engine is very close to your point of use, the breakeven for the cost of insulating the long plumbing run well could make your breakeven point beyond the life of the engine, or perhaps yours.









EdDee

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Re: heat exchanger
« Reply #4 on: October 17, 2018, 11:57:10 PM »
Hi Guys,

I have been using a tube in tube exchanger for a few years now. On about 8hp, with around 2kw load, the 3m long exchanger heats up 300L approx from around 15C to 75C in about 2 to 3 hours.... Currently we have the lister down for rebuild and have been using a babbington burner on a 700mm long exchanger doing the same job, but burning about 30 to 40% more fuel for the same time period... the bab puts out way more heat, much more goes to the stack because of the short exchanger, but in most more ways, better to run from a heating pov if electricity is not needed...

Cheers
Ed
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veggie

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Re: heat exchanger
« Reply #5 on: October 18, 2018, 05:23:34 PM »

One thing that I was thinking about over the years is a pipe-to-air exchanger on the exhaust.
If you are planning to heat the same room that the engine located, maybe a very long run of exhaust pipe within the room (before exiting the building) would give off a fair bit of heat like a radiator.
The long pipe would work best if fitted with cooling fins. (Called a Fin-Tube)
The idea being that most of the exhaust gas would be cooled drastically before exiting the building by losing it's heat to the finned pipe.

just a thought...

veggie
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BruceM

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Re: heat exchanger
« Reply #6 on: October 18, 2018, 05:35:08 PM »
No free lunch-  cooling exhaust gas yields precipitation of goop inside pipe, reducing heat transfer and ultimately a horrible cleanup job.  For exhaust heat capture, that issue must somehow be accommodated. 

I'd love to see what Mobile Bob came up with...his work on efficiency of automotive alternators at higher voltages was very impressive. 


BruceM

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Re: heat exchanger
« Reply #7 on: October 18, 2018, 06:50:04 PM »
"I think given a length of pipe which both ends can be opened for wet flushing or Physical removal with a brush, cleaning should be easy and the heat transfer effective."

Sounds like a good plan, Glort.  Veggie's clamp on tube fins is also a good way to increase surface area.

I have a crazy idea-  what if the exhaust was directed into a barrel of water, with a diffuser to get lots of small bubbles throughout the tank for good gas to water heat exhange.  With lots of pex or copper tube for heat exchange in the tank.  You'd have to dispose of the water periodically, perhaps after adding detergent and agitating via drill mixer.  Of course this would only work if you could use heated water below 100F/boiling.