Author Topic: Flash Steam Generation  (Read 311 times)

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eigenmorph

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Flash Steam Generation
« on: January 03, 2018, 07:11:34 AM »
I came across the attached article on a proposed steam generator in a
1952 Model Engineer Magazine. I hope it is of interest to other experimenters.

The principle of using the water to
extract heat directly from the combustion products is the same as that used
on the Brayton Engine with water injection.

In the Brayton engine, one cylinder provided compressed air while a second was used for combustion on a 2 stroke principle. It was essentially a supercharged 2 stroke. In the case of the Brayton, water injection may have been employed primarily for internal cooling purposes.
 
One appeal is that water expands some 1700 times on conversion to steam at atmospheric pressure. A
second attraction is that the very high temperatures which give rise to
NOx byproducts are avoided. Engine cooling should not be required and the maximum amount of heat is obtained from the combustion process.

The thermodynamic issue to consider relates to the principle that
highest efficiency is achieved when expansion of the gases involved occurs
across the widest possible temperature difference. This is based on
Carnot's thermodynamic model of a perfect gas. Using Carnot's
principles, the "Air Standard Cycle" is employed for comparing different
internal combustion engine configurations.

The presence of steam limits the upper temperature. However, steam is
anything but a perfect gas and the combustion process is similarly complex.
Real engines are not remotely "Carnot" in operation.

JW

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Re: Flash Steam Generation
« Reply #1 on: January 03, 2018, 02:12:14 PM »
Eigenmorph  its not uncommon to see steam ejected into a burner and it does improve latent heat of vaporization. This is one thing a monotube cannot do.

I promised I would discuss Carnot theory with another fellow who understands the concept better than me.

The reference you have there is interesting...

JW

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Re: Flash Steam Generation
« Reply #2 on: January 03, 2018, 03:32:56 PM »
I just wanted to show the images were talking about

11018-0

The water wall is surrounding the combustion chamber, preheats ejected water/steam. I think the discharge will be corrosive. Your best option with this steam generator is to use an reaction turbine electric generation. But your not getting away with solid fuel with this design.

JW

george65

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Re: Flash Steam Generation
« Reply #3 on: January 04, 2018, 05:31:19 AM »

If this setup is to provide steam at pressure, the burner would have to run at a higher pressure still. I note the diagram says the flame is capable of burning without atmosphere so is this able to run on compressed air or does it need oxygen?
Either way it would seem an expensive burner to run because you are going to need to compress the air at least and to a high pressure as well which would make blowers an unlikley proposition unless the steam was very low pressure.

What is the application for this style burner?

JW

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Re: Flash Steam Generation
« Reply #4 on: January 04, 2018, 06:53:50 AM »
I'm not sure if this has a dedicated use. Yes air has to be supplied (most likely shop air). I have been working with a solid fuel combustion and when I used shop air it worked perfectly. I have spent a lot of time using a 12 volt blower eventually will get it right. There is a pdf on the first post that may answer some of your questions George. 

JW

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Re: Flash Steam Generation
« Reply #5 on: January 04, 2018, 03:34:58 PM »