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 Post subject: Re: Economizer tube material
PostPosted: Wed Dec 06, 2017 7:34 pm 
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<random technology aside>

I'm curious when the first company starts offering custom cast iron casting made from a 3d printing file... print the part in foam, cast it using lost foam in iron.

</random>

As to getting electronic components, digikey is pretty good. The real issue is that most are cheap, and shipping is always a thing... of course, driving off-island isn't exactly cheap either, so I guess one ends up paying the 'living in paradise' tax one way or the other.

- Bart

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 Post subject: Re: Economizer tube material
PostPosted: Wed Dec 06, 2017 8:30 pm 
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barts wrote:
I'm curious when the first company starts offering custom cast iron casting made from a 3d printing file... print the part in foam, cast it using lost foam in iron.


You know people do this right now.

Shapeways can 3d print you into 80 materials. https://www.shapeways.com/materials?gcl ... Z8QAvD_BwE

Pick any of those that gives you enough detail into something cheap like plastic.

Then turn around and send the 3d print to Cattail foundry as a pattern.

Cattail is run by Amish, so you can't ask them to 3d print your pattern for you. :) But they will take that and know how to cast iron if the pattern is castible. Traction engine folks are already doing this.

-CB


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 Post subject: Re: Economizer tube material
PostPosted: Wed Dec 06, 2017 10:34 pm 
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First the light emitting diode.

Then the ink emitting diode (ink jet printer).

Now the plastic emitting diode (3D printers).

And somewhere mixed in there was the advent of the politician emitting diode (currently malfunctioning badly). Also known by its acronym PEDophile.

That's the end of my thread highjack. Back to economizers.

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 Post subject: Re: Economizer tube material
PostPosted: Wed Dec 06, 2017 11:56 pm 
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barts wrote:
In any case, I'll agree that the real value of the Cu/Ni tubing is that it's much easier to install than 1/4" steel pipe; the heat transfer differences are minor in practice, given the low air flow velocities around the economizer.


I'm confused. In my bonnet the air flow can be very considerable. The simulation of my manual operated nozzle indicated up to mach 1, although Fred says that figure from the simulation is not valid.
With the spiral nozzel using the toledo exhaust gets a lot more air moving. Why do you say "low air flow velocities'?

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 Post subject: Re: Economizer tube material
PostPosted: Thu Dec 07, 2017 12:03 am 
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cyberbadger wrote:
barts wrote:
In any case, I'll agree that the real value of the Cu/Ni tubing is that it's much easier to install than 1/4" steel pipe; the heat transfer differences are minor in practice, given the low air flow velocities around the economizer.


I'm confused. In my bonnet the air flow can be very considerable. The simulation of my manual operated nozzle indicated up to mach 1, although Fred says that figure from the simulation is not valid.
With the spiral nozzel using the toledo exhaust gets a lot more air moving. Why do you say "low air flow velocities'?

-CB


As I said earlier, "Boats exhausting up the stack should see more benefit for a given size of economizer since exhaust gases will be higher."
I said higher somehow rather than faster...

A boat operating on natural draft sees relatively low stack velocities, and one needs more economizer surface area to capture the heat. When exhausting up the stack (or using fan forced draft), the velocities are much higher, and the air-metal film isn't such a barrier.

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 Post subject: Re: Economizer tube material
PostPosted: Thu Dec 07, 2017 12:28 am 
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barts wrote:
As I said earlier, "Boats exhausting up the stack should see more benefit for a given size of economizer since exhaust gases will be higher."
I said higher somehow rather than faster...

A boat operating on natural draft sees relatively low stack velocities, and one needs more economizer surface area to capture the heat. When exhausting up the stack (or using fan forced draft), the velocities are much higher, and the air-metal film isn't such a barrier.


Got it.

So general question, it seems like you can have economizers in different places. But I think that has to do with naturally where it makes sense to put them for the particular steam contraption? And the boiler/plant configuration I believe?

The ones on some traction engines with an engine crankshaft eccentric powered pumps the economizer/prehearter can be on the side. In this picture you can see the green cylinder that has "Case" written on it uses the exhaust to preheat the water (I believe it's a coil in that cylinder) http://www.gouldstudios.com/images/1-case.jpg

So basically throwing a coil of in my bonnet does the same as that right? Why did Case do it that way and not throw a coil in their smokebox?

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 Post subject: Re: Economizer tube material
PostPosted: Thu Dec 07, 2017 1:06 am 
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You are confusing a feed water heater (uses exhaust steam to heat feed water) with a economizer (uses flue gases to heat feed water).

You can have both; the steam is hottest just after leaving the cylinder so grab it there, the economizer needs to be in the smokebox. Note that the steam exhaust will be cooler than the flue gasses by a lot unless your engine is really inefficient; you want to keep these separate.

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 Post subject: Re: Economizer tube material
PostPosted: Thu Dec 07, 2017 1:30 am 
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barts wrote:
You are confusing a feed water heater (uses exhaust steam to heat feed water) with a economizer (uses flue gases to heat feed water)

Thanks, this makes sense. I thought I was missing something and I think that's it.

Ok, normally I don't shop at walmart, but 25ft of 1/2 OD cupro for less then $100?

Does this look reasonable for an economizer?

https://www.walmart.com/ip/Copper-Nicke ... 3=&veh=sem

-CB


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 Post subject: Re: Economizer tube material
PostPosted: Thu Dec 07, 2017 2:08 am 
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Yes, that's the same place. If you're using an injector for your feed, calculate your pressure drop at your injector feed rate; injectors rely on minimal pressure difference between the steam and the feed water back pressure.

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 Post subject: Re: Economizer tube material
PostPosted: Thu Dec 07, 2017 4:34 am 
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Hmm. I don't know how to calculate that, and I have not measured it.

The concept is weird to me, and although it is mentioned in an injectorers manufacturer literature, it's against what I think of as the "reference implementation" of how to pipe up an injector. Normally you want it as short and direct as you can manage.

But if the check valve is right after injector what does the injector feel for back pressure? This is a simple question that I should probably know the answer to but I don't exactly.

Here are the specs for the penberthy on Nyitra, an AA-328.
Image

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