Heat exchanger for generator exhaust

[CompoSimmonite]

Last week I picked up a Honda 12/24v battery charging generator to use as a range extender for my mobility scooter. I plan on making a single wheel trailer / platform to add behind the scooter to carry it but that will put the exhaust pointing towards the back of the seat so need to extend and route it rearwards.
Also for winter I'd like to make a simple cabin enclosure for the whole scooter so am thinking why not use this exhaust extension to make a heat exchanger and duct warm air (either blown with a computer fan or maybe the engines cooling fan) into the cabin.
The idea for the heat exchanger is 15mm copper pipe with end feed 22mm to 15mm fitting that have the internal pipe stop filed out so they will slide down the pipe silver soldered in place. The reducers will then be cut to make petals / vanes or whatever and increase surface area air has to pass over and therefore, hopefully, increase heat output. The whole lot will then be encased in 50mm plastic waste pipe which I can see is suitable for up to 75 degrees temp.

What is peoples opinion of this idea ?
Is silver soldering OTT and ordinary plumbing solder be sufficient ?

Cheers.

Paul H

 

[Cyberprog]

Why not get a scrap intercooler and adapt that?

 

[julianf]

My vote would go on an EGR cooler.

People often do that kind of thing with CHP systems.

 

[CompoSimmonite]

My vote would go on an EGR cooler.

People often do that kind of thing with CHP systems.

Never heard of them before so just looked on eBay and they look like suitable for adapting - thanks.

Paul H

 

[Cyberprog]

Yep, that's true, late TD5's used a heat exchanger on the EGR, but that was a water/air exchanger, while it's good for cooling, I'm not sure it'll be any good for blowing air across as an air/air exchanger. I think most EGR exchangers will be similar, unless you plan on having a water circuit and a second water/air exchanger with a blower, but you'll lose a lot of energy in that.

 

[Rig Pig]

I don't think copper pipe is a good idea for an exhaust heat exchanger ( I seem to remember being told about an engine someone fitted with a beautiful copper exhaust that had horrendous resonation problems that killed the engines performance) a finned steel heat exchanger with a fan to blow air passed it would be fairly easy to build.

 

[rtbcomp]

Some interesting stuff here http://www.accessnorton.com/might-stupid-question-copper-exhausts-t4857.html

The main objections seem to be heat conduction spoiling the tuning and the copper work hardening.

When I was first starting out playing with cars we discussed copper exhausts and the pollution aspect was brought up then. It could be an old wives tale though!

Google "Copper exhaust pipe" - there's a lot out there!

 

[sardine]

An EX400 perchance ?

I've got one somewhere, on my boat.

 

[captain-destructo]

what about the heat exchanger from an old VW

 

[CompoSimmonite]

An EX400 perchance ?

I've got one somewhere, on my boat.

It's an ED400 - very popular with boat owners as it allows then to charge batteries without running main engine. Mine cost me £50 which is an absolute bargain as £150-200 seems to be the going rate for one in GWO despite being an old unit.

I've been reading up about copper exhausts and agree not a suitable material.

Paul h

 

[Wallace]

What about using a VW Beetle exhaust heat exchanger? Might be a bit free flowing for the engine size and need restricting.

 

[CompoSimmonite]

What about using a VW Beetle exhaust heat exchanger? Might be a bit free flowing for the engine size and need restricting.

Good idea however after owning a couple of Beetles I know their heat exchangers probably weight almost as much as the whole genny !
Think I'm going to "investigate" making one out of a couple of stainless exhaust elbows and a short length of stainless exhaust pipe with a 15mm piece of stainless plumbing pipe running through the centre. Then I can use a short length of stainless flexi pipe to connect to genny exhaust stub.

Paul H

 

[Wallace]

Could you not heat the cabin with an electric heater as you will be able to charge on the move?

 

[the snooper]

I would simply build a small box with multiple mild steel tubes in it to maximise transfer area with a small fan and outlet for a duct into the cab, but I would make it to bolt straight to the head to get maximum heat, then bolt the silencer to that, that way you could point the exhaust in any direction you wanted

 

[Robotstar5]

I plan on making a single wheel trailer / platform to add behind the scooter to carry it but that will put the exhaust pointing towards the back of the seat so need to extend and route it rearwards.
Also for winter I'd like to make a simple cabin enclosure for the whole scooter so am thinking why not use this exhaust extension to make a heat exchanger and duct warm air (either blown with a computer fan or maybe the engines cooling fan) into the cabin.

You're not related to Rowland Emett are you?

 

[sardine]

It's an ED400 - very popular with boat owners as it allows then to charge batteries without running main engine. Mine cost me £50 which is an absolute bargain as £150-200 seems to be the going rate for one in GWO despite being an old unit.

I've been reading up about copper exhausts and agree not a suitable material.

Paul h

Oh yeah , i meant ED400, I have the same one, not many people have ever heard of them so they can be found cheap ish on eBay. They are very high quality machines.