Forced Air Diesel Fuel Burner

[Toymaker]

I agree with the physics of emitting radiation, but not always in the infra-red, which is why an efficient blue flame and similar yellow flame feel different when the human body detects the radiation. Wavelength or frequency makes a big difference I think?

It's more than a little counter-intuitive, but IR (Infra Red) radiation carriers the least amount of energy. Higher frequencies of light, such as Blue and UV carry the most energy. For reasons I don't understand, our bodies don't feel UV light, which is why you can get a nasty sunburn on a cloudy day and not feel it until that evening when your skin turns bright red from cellular damage. Our bodies can feel the lower light frequencies of IR & Red but not the higher frequencies of Blue & UV. So we humans perceive IR & Red heat objects to be hotter,...but that's just our senses tricking us.

Because you are using freon (whatever) instead of water, with its temperature limitation, I respect your plan for using the hot exhaust gas, as by adding extra air you can effectively cool the exhaust to control temperature . ... I am sure you will have done some heat-flow sums to get a good idea for the heat absorption capacity of all those coils to the gas ?

I've done a few calculations using the Conductive Heat Transfer Calculator I found in The Engineering Toolbox.
I'm aware that determining heat transfer through the tubing wall is only one step,...one must also determine heat transfer into the liquid or gas inside the tube. But for now, looking at only the required surface area of the tube and using the following inputs for the above online calculator:

200 W/(mK) thermal conductivity of the Aluminum tube's wall.
0.006 sqr meters (9.3 sqr inchs) total wall surface area.
500 C exhaust gas temperature (I'm assuming temperature drops from the much higher exhaust gas temp.)
184 C water (Freon) temp inside the tube
0.00071 meters Wall thickness.

Given the above inputs, the calculator tells me that I can transfer 534 kW through just 9.3 sqr inchs of tube surface. At first glance, that answer seems wildly impossible, but several other online calculators yield similar results, so for now, I will accept this answer as accurate. Your thoughts?

I have not yet determined exactly how to calculate heat transfer between the inner tube wall and the working fluid flowing through the tube. Still looking for an online calculator for this little problem.
Got any suggestions?

The only suggestion I can make is that the coils are spaced by approx 1 tube diameter, which is a "convenient" standard used in water tube boilers for a number of reasons, not the least being gas flow.
Otherwise, your burner-boiler design is a bit distant from my expertise.
Just a thought... from the red-hot end plate, where is all that heat going to be collected, as there isn't much boiler where that red-heat is shining? Is the end plate (RH end of drawing), where it looks like the hot vapour is exiting the boiler, heated by the radiant heat from the burner end plate? This may be the superheater you mention?
K2

Good assumption Steamchick
I posted the left photo in my Ambitious ORC Turbine thread some months back; it shows the 8 steam tubes feeding into the turbine's steam chest. The right photo shows what I jokingly refer to as my steam tube spider, because it has 8 "legs"; it's mounted inside the boiler with the black side facing the burner exhaust red hot end plate, where it's black surface will absorb lots of radiant heat. The spider will act as the final super heat area before the steam leaves the boiler. The non-boiler side of the spider contains a thermal sensor which will send temperature data to the micro-controller. BTW, for those whom are curious, the black coating on the spider is Type 3 hard coat anodize, which is essentially a 2 mil thick electroplating of Aluminum Oxide; it's thermal conductivity is horrible (30W/mK) but it's resistance to corrosion in high heat conditions is just amazing. My plan is to hard coat all the aluminum tubes in the boiler to protect the tubes from the corrosive affects of exhaust gasses on bare aluminum; the coating will slightly decrease thermal conduction across the tube walls, meaning I will need more tubing, but avoiding corrosion is well worth the additional tube length.

None of the tubes are as yet welded in place, and the tubes in the right photo aren't even the correct shape,...I placed the tubes in their correct location on the spider body just to take the photo and give readers an idea of what it will look like. The final tubes will form 8 interlaced coils looking a lot like interlaced coil springs, except more widely spaced to allow for good air flow. Each "spider leg" (right photo) will be 18" long and at it's end will be welded into a "Y" junction with another "leg" thereby reducing the leg count down to 4. At the moment, the 18" length is 100% SWAG !! (Silly Wild Arss Guess)

 

[Steamchick]

Impressive and ambitious engineering!
The black anodised surface will adequately conduct heat to the aluminium beneath as it is so thin, and homogenous with the aluminium.
The heat flow ("transfer 534 kW through just 9.3 sq. in. of tube surface") is dependant on sufficient gas passing up the tube to carry that heat away - at the temperature you use in the calculation. For that you need to study the thermal flow into the gas - from input temp (liquid?) to output temp (superheated gas?) through 3 phases. liquid from input to boiling point (at the pressure chosen) then latent heat of vaporisation to change it to gas, followed by heating the gas to the superheat temperature. The thermal capacity of liquid and gas (J/gm/deg.C) should be in your data tables. For water, they are usually combined into "Steam tables". You will simply be following the same process.
From your total energy input (maybe 60% of the burner fuel heat? kW = JOULES per second) you can the determine the mass flow of gas...(Kg/second).
If you want more details, send me you gas data sheet and I'll do a model calculation for you. But I think you can do it.
Really, these calculations should be in any good refrigeration text book, as the "hot-side" calcs. (liquid to gas) - I guess?
K2

 

[Steamchick]

Another odd thought... Why do you nee the spider's legs? I may have otherwise thought it easier to just have the collector - with appropriate drillings/internal passages bolted directly onto the end piece of what I think is your turbine housing? Or is there some problem needing separation of the end bearing from the hot vapour inlet?
K2

 

[Toymaker]

Another odd thought... Why do you nee the spider's legs? I may have otherwise thought it easier to just have the collector - with appropriate drillings/internal passages bolted directly onto the end piece of what I think is your turbine housing? Or is there some problem needing separation of the end bearing from the hot vapour inlet?
K2

The two main reasons for keeping the 4 major modules, (Burner, Boiler, Turbine, & Power Blower) as separate pieces is because it makes testing and characterizing each module much easier. The second reason is for safety; IF during boiler testing things go badly and I run out of working fluid, or I find that my heat transfer calculations were terribly wrong and I end up melting the aluminum spider,...having a little distance between burner and turbine will prove quite beneficial.

In the many months (years?) to come, when I finally get this first prototype up and running, I'm already thinking of many improvements I will make to the second unit,... and one of those improvements will very likely be your above suggestion.

 

[Steamchick]

I shall have to consult my book... but water tube boilers, fired with blowlamps (like your gas temperatures) boil 5 cu. in.of water per minute per 100 sq. in. of water tubes at 100psi. (?)... from what I remember? Maybe you can relate to that?
I'll check when I get back to "the book".
K2

 

[Toymaker]

I shall have to consult my book... but water tube boilers, fired with blowlamps (like your gas temperatures) boil 5 cu. in.of water per minute per 100 sq. in. of water tubes at 100psi. (?)... from what I remember? Maybe you can relate to that?
I'll check when I get back to "the book".
K2

One glance at all the other working mobile boilers tells me there's something wrong with the 9.3 sqr inch number the online calculator is giving me. It seems very likely that I'm not using the calculator correctly. Gonna take a lot more head scratching to figure this one out.

 

[Steamchick]

Hi Toymaker,
As you doubt the online calculator results:
I have considered the "parallel" case of steam generated from feed water: (This uses steam tables).
My simple calculation, that may give you a model upon which to do you equivalent calculation for your refrigeration gas, is as follows:

My book tells me a water tube boiler can deliver 5cu.in/min. of "boiled water" (steam) per 100sq.in. of tube surface:
Water = 0.0316 lbs/cu.in
@ 100psi: Steam needs 1184BTU/lb total heat from 15C.
=> 1 cu/in needs 42.778BTU/cu.in.
@5 cu.in/min => 300cu.in/hr: need 12899BTU/hr. = 3.761kW.
I.E. if we have a water tube boiler able to generate steam at 5cu.in./minute at 100psi /100sq.in. surface, from water at 15C (supplied) we need: 3.761kW /100 sq.in of heated surface of water tubes.
If we have 150kW, we can do this with a boiler of ~4000sq.in surface area, but allowing for 60% system efficiency (Much of the gas blows past tubes, and it cools as it travels and expands through the boiler and delivery pipework.) we should only expect 60% of the 150kW to be transmitted to “Steam energy”.
So the boiler should be planned with 4000sqin (min). But steam expectation at 100psi should only be 5 x 40 x 60% = 120cu-in of water boiled => 237 x 120 = 28440 cu.in. of steam per hour at the engine.
NOTE: This does not consider superheating, which extracts “heat” from the combustion gases, reducing the available “steam generating heat”, but transmits this heat more efficiently to the engine, perhaps increasing system efficiency to ~75%?

I hope this makes sense? - I suggest you copy this onto your own document - then substitute your figures as appropriate?

I have not seen the tube size you are planning to use, but if 8mm or 5/16" diameter, you need just over 1 inch of length per sq. in of surface area. => for your 9.3 sq.in of surface area you need a 10" long tube! Now that does sound like a factor of 100 (? - Maybe 1000?) "wrong" to me ...?
I hope this helps. And I hope I have got it right! (First attempt I was a factor of 100 wrong... now corrected!).
K2

 

[Toymaker]

Hi Toymaker,
As you doubt the online calculator results:
I have considered the "parallel" case of steam generated from feed water: (This uses steam tables).
My simple calculation, that may give you a model upon which to do you equivalent calculation for your refrigeration gas, is as follows:

My book tells me a water tube boiler can deliver 5cu.in/min. of "boiled water" (steam) per 100sq.in. of tube surface:
Water = 0.0316 lbs/cu.in
@ 100psi: Steam needs 1184BTU/lb total heat from 15C.
=> 1 cu/in needs 42.778BTU/cu.in.
@5 cu.in/min => 300cu.in/hr: need 12899BTU/hr. = 3.761kW.
I.E. if we have a water tube boiler able to generate steam at 5cu.in./minute at 100psi /100sq.in. surface, from water at 15C (supplied) we need: 3.761kW /100 sq.in of heated surface of water tubes.
If we have 150kW, we can do this with a boiler of ~4000sq.in surface area, but allowing for 60% system efficiency (Much of the gas blows past tubes, and it cools as it travels and expands through the boiler and delivery pipework.) we should only expect 60% of the 150kW to be transmitted to “Steam energy”.
So the boiler should be planned with 4000sqin (min). But steam expectation at 100psi should only be 5 x 40 x 60% = 120cu-in of water boiled => 237 x 120 = 28440 cu.in. of steam per hour at the engine.
NOTE: This does not consider superheating, which extracts “heat” from the combustion gases, reducing the available “steam generating heat”, but transmits this heat more efficiently to the engine, perhaps increasing system efficiency to ~75%?

I hope this makes sense? - I suggest you copy this onto your own document - then substitute your figures as appropriate?

I have not seen the tube size you are planning to use, but if 8mm or 5/16" diameter, you need just over 1 inch of length per sq. in of surface area. => for your 9.3 sq.in of surface area you need a 10" long tube! Now that does sound like a factor of 100 (? - Maybe 1000?) "wrong" to me ...?
I hope this helps. And I hope I have got it right! (First attempt I was a factor of 100 wrong... now corrected!).
K2

Your 8mm guess for tube size is spot-on, as that is the size I'm using.

I will need to read over your example a few times before it all starts to sink in; certainly, thanks for the work done.

Whenever I run into problems where the math just seems nonsensical, I will sometimes examine successful working examples to see how they solved the problem. I mentioned the SES burner-boiler in a previous post because like my burner-boiler, the SES unit was also designed for light weight, small size, and a HP output similar to mine. The system shown below produces in excess of 130HP using water as the working fluid and weighs a mere 100 lbs. It also has a total tube surface area of 75.3 sq ft, (10,843 sq in).

So, my early calculations of 9.3 sq in would seem to be off by a factor of 1000, as 9,300 sq in seems about right.

 

[Steamchick]

And that makes my 4000sq.in. seem a bit small! One thing I note: As drawn, there appears to be "no gaps" in the coils to permit hot gas to pass through. So it won't work. All the boiler books I have seen say approx. 1 diameter spacing is the optimum without choking the tube matrix (You want hot gas to get to all tubes, not be cold when it gets further along, or have shielded tubes.
A Gas Burner paper suggests the gas egress should be through a cross sectional area approx. 4 x the inlet CSA. - For each "chamber" of a naturally aspirated burner. Of course, if you have a chamber pressure/flow calculator, you can refine that for any pressure/flow. The passage through the "chamber" should be similarly expanding, to avoid choking.
(I have written an Excel spreadsheet for a job, but it isn't appropriate to this task, and may not be very real anyway?).

Getting "technical" - as I see it:
In your burner design, you have 3 inputs and 3 dynamic gas streams - which become one:
The air jet kinetic energy comes from the initial pressure, which is exchanged for velocity (V1): The kinetic energy (1/2 m1 v1 sq) of the injector air is shared with the fuel to produce the aerosol cloud of fuel in air, so this becomes m1 v1 sq = m1 v2 sq + m2 v2 sq: and the net cloud both moves with velocity v2, and has a slightly above atmospheric pressure from the velocity v2. And Newton said there is a law of conservation of Momentum such that m1v1 + m2 x v0 (because the fuel is at rest v0 is a real zero!) = (m1 + m2) x v2.
But then (without changing masses of this cloud) we add the secondary air: at velocity v3 and mass flow m3: such that (when the burner is balanced) this becomes a stream of hot gas- at a much higher pressure due to the addition of the energy of combustion (temperature). So the pressure entering the "heat exchanger" (the annulus past the end plate of the burner) is mostly made from the heating of the whole fuel air mass. This is the initial pressure in the heat exchanger: The MASS flow must be constant now all 3 masses have combined, but the velocity will change as the volume of exhaust reduces as it is cooled by the heat exchanger. If you develop a spreadsheet giving all the pressures and volumes that you can deduce, you will draw a diagram - as did Otto and Carnot when they produced their different cycles for internal combustion engines. (I think jet engineers do a similar thing to this, so there's some research for you?).
I am sure you have a notion of the flame temperature just post combustion, as well as at the end of the heat exchanger, because it can't be colder than the pipework of gas at this point. So maybe you can deduce the pressure at the outflow of the heat exchanger (P1 x V1/T1 = P2 x V2/T2, etc.) and volume flow rate through the system? Total Mass flow rate must be a constant). Then you can deduce a reasonable spacing for tubes as the gases progress through the heat exchanger. This should turn a guess into a guestimate! - and deliver a better finished system as a result.
This is not simple to grasp, but I'll try and help - if you want to progress with this level of design?
Cheers,
K2

 

[Toymaker]

And that makes my 4000sq.in. seem a bit small! One thing I note: As drawn, there appears to be "no gaps" in the coils to permit hot gas to pass through. So it won't work. All the boiler books I have seen say approx. 1 diameter spacing is the optimum without choking the tube matrix (You want hot gas to get to all tubes, not be cold when it gets further along, or have shielded tubes.
A Gas Burner paper suggests the gas egress should be through a cross sectional area approx. 4 x the inlet CSA. - For each "chamber" of a naturally aspirated burner. Of course, if you have a chamber pressure/flow calculator, you can refine that for any pressure/flow. The passage through the "chamber" should be similarly expanding, to avoid choking.

Since we know the SES burner-boiler was built, tested, and works exceedingly well, I think we can safely assume it's the drawing that isn't exactly accurate. Also, the larger diameter tubes, including the tubes shown as two concentric circles, represent finned tubes. Seems possible to me that finned tubes could be placed such that their fins are actually touching and yet still leave plenty of space between tube walls.

Getting "technical" - as I see it:
In your burner design, you have 3 inputs and 3 dynamic gas streams - which become one:
The air jet kinetic energy comes from the initial pressure, which is exchanged for velocity (V1): The kinetic energy (1/2 m1 v1 sq) of the injector air is shared with the fuel to produce the aerosol cloud of fuel in air, so this becomes m1 v1 sq = m1 v2 sq + m2 v2 sq: and the net cloud both moves with velocity v2, and has a slightly above atmospheric pressure from the velocity v2. And Newton said there is a law of conservation of Momentum such that m1v1 + m2 x v0 (because the fuel is at rest v0 is a real zero!) = (m1 + m2) x v2.

I don't think we need to worry about the air and fuel velocity energy as anything that adds significantly to the overall energy output of the burner-boiler unit. The velocity of the fuel-air mixture, V1, is provided by a fractional Hp electric motor. Similarly, the velocity of the mixing air, V2 is also sourced from a fractional Hp blower. The energy provided by both of these motors combined is less than one Horsepower.

<snip>
This is not simple to grasp, but I'll try and help - if you want to progress with this level of design?
Cheers,
K2

I appreciate your offer of assistance Steamchick. For now, I've started giving myself a better understanding of the basics of Thermodynamics by listening to an online course covering Heat Transfer. The course is not boiler-specific, and the first few chapters have been very basic, but they have familiarized me with the terminology of heat transfer. Once I've completed this course, hopefully I'll have a much better understanding of heat transfer within a boiler or at least be able to ask smarter questions.

 

[Steamchick]

Hi Toymaker.
Much better than listening to my amateur wittering! Enjoy the course!
K2

 

[ajoeiam]

Hi Toymaker,
As you doubt the online calculator results:
I have considered the "parallel" case of steam generated from feed water: (This uses steam tables).
My simple calculation, that may give you a model upon which to do you equivalent calculation for your refrigeration gas, is as follows:

My book tells me a water tube boiler can deliver 5cu.in/min. of "boiled water" (steam) per 100sq.in. of tube surface:
Water = 0.0316 lbs/cu.in
@ 100psi: Steam needs 1184BTU/lb total heat from 15C.
=> 1 cu/in needs 42.778BTU/cu.in.
@5 cu.in/min => 300cu.in/hr: need 12899BTU/hr. = 3.761kW.
I.E. if we have a water tube boiler able to generate steam at 5cu.in./minute at 100psi /100sq.in. surface, from water at 15C (supplied) we need: 3.761kW /100 sq.in of heated surface of water tubes.
If we have 150kW, we can do this with a boiler of ~4000sq.in surface area, but allowing for 60% system efficiency (Much of the gas blows past tubes, and it cools as it travels and expands through the boiler and delivery pipework.) we should only expect 60% of the 150kW to be transmitted to “Steam energy”.
So the boiler should be planned with 4000sqin (min). But steam expectation at 100psi should only be 5 x 40 x 60% = 120cu-in of water boiled => 237 x 120 = 28440 cu.in. of steam per hour at the engine.
NOTE: This does not consider superheating, which extracts “heat” from the combustion gases, reducing the available “steam generating heat”, but transmits this heat more efficiently to the engine, perhaps increasing system efficiency to ~75%?

I hope this makes sense? - I suggest you copy this onto your own document - then substitute your figures as appropriate?

I have not seen the tube size you are planning to use, but if 8mm or 5/16" diameter, you need just over 1 inch of length per sq. in of surface area. => for your 9.3 sq.in of surface area you need a 10" long tube! Now that does sound like a factor of 100 (? - Maybe 1000?) "wrong" to me ...?
I hope this helps. And I hope I have got it right! (First attempt I was a factor of 100 wrong... now corrected!).
K2

Hopefully not inappropriate - - -

Your calculations are very interesting.
Where are the formulas derived from?
If I want to change values does the 'steam table' give accurate enough information that said table is all that is used? (other sources for formulas or ?????)
I understand its a complicated topic - - - but - - - want to work my way through this kind of design process.
You mention superheating being 'different' - - - is such used in the large power plants to your knowledge?

TIA

(If it would be better served to split this onto its own thread - - - please.)

 

[Steamchick]

My simple maths comes from K.N. Harris - Model boilers and boilermaking.
The standard Steam Tables are available anywhere on the net. But I used Harris as that was quicker than the web.
Essentially, if you have never eerie need the steam tables, the are a pre-computer device to quickly read the values for calculation.
Namely the enthalpy of steam, plus thermal capacity of water, plus the latent heat of evaporation - all combined into values that change with temperature and pressure. Tables save half the calculation, but you can find all the stuff if you enjoy browsing the erb. (Personnally, if there is a table in a book I find it saves time! The web is SO SLOW AND TEDIOUS, when you are familiar with other Old fashioned tools!).

Superheating. A bit of history.
Newcomen invented an engine where steam displaced air in a cylinder, which then was condensed and the latent heat removed so the ensuing vacuum allowed atmospheric pressure to drive the piston and the water pump. It didn't use the thermal capacity of watrr, nor any pressure of steam.
James Watt decided there was power in the steam, so while at low pressure, he used it to push on one side of the piston, instead of Newcomen's atmospheric pressure, as well as the vacuum of the exhausting side of the piston, to increase the pressure difference on the piston to incresse the efficiency of the engine. He also (like Eddisson and others) took all the ideas from others and experimented, finding the best of the options, and patented them which made him and his investors loads of money selling licences. Not a daft lad! His engines used both the steam-heat (as pressure) tuo push the piston, and latent heat (from the condenser creating sub-atmospheric pressure) "pulling" the piston. So a step forward.
Then Trevithic took steam at relatively high pressure, realising the true power of the energy in the steam as steam pressure to take a leap forward from large stationary engines to smaller mobile plant. Often ignoring the latent heat because he simply dumped steam out of the engine, instead of using the latent heat in a condenser.
Then later, - don't know when - someone realised the steam is simply a gas that holds energy - released when it expands. So the suprrheater was developed. This simply adds a lot more heat to the steam, so without increasing the "losses" from heating water from cold to boiling point, you can transfer a lot more energy in superheated steam compared to "wet" steam - which generates water droplets immediately it loses some energy. Superheating is all the heat gained by the steam AFTER it leaves the water zone and is heated further. This "Dry" steam is absolutely necessary in power stations in steam turbines, that cannot tolerate droplets of water at the sonic speeds achieved in the turbines. So these power plants cannot use the energy in the thermal capacity of water, nor the latent heat of water, but use the difference of the enthalpy of the superheated steam (pressure) into the turbine, and the enthalpy of the still superheated (dry) steam at the exhaust from the turbine.
Does that help?
K2

 

[Steamchick]

Hi again Tia.
Do you want me to write the numbers with calculations on a sheet - for you to check an find my mistakes (I usually hide something really obvious in them - that I can't see!). I DON'T MIND. In fact I would appreciate ir. The use of a buddy check was standard practice in one design office where I worked, but it doesn't happen now everyone has computers to make the mistakes for them...
It will take a day or so.I can use your direct comma link until proven OK.
In my head, the relevance of these calcs is to compare real results for 150 kW between water and Toymaker's Refrigerant.
I.E. 4000sq.in. for water against 10sq.in. for refrigerant seemed wrong , but against 12000 sq.in. seems comparible, without knowing the thermal capacity of Refrigerant, latent heat and enthalpy of the vapour, and Toymaker's ideas of the various temperatures and pressures.

But sometimes my head goes off in the wrong direction, so I welcome all feedback from you.
Cheers,
Ken

 

[Toymaker]

Hi again Tia.
<snip>
In my head, the relevance of these calcs is to compare real results for 150 kW between water and Toymaker's Refrigerant.
I.E. 4000sq.in. for water against 10sq.in. for refrigerant seemed wrong , but against 12000 sq.in. seems comparible, without knowing the thermal capacity of Refrigerant, latent heat and enthalpy of the vapour, and Toymaker's ideas of the various temperatures and pressures.

But sometimes my head goes off in the wrong direction, so I welcome all feedback from you.
Cheers,
Ken

At this time, my first choice for working fluid is R-123. You should be able to find all the physical properties you need in this online pdf R-123 Data Sheet. Here's a quick overview:

There are several good reasons to use a refrigerant (Freon) instead of water as the working fluid in a small steam turbine, but one of the most important for me is the difference in gas expansions. Most large steam turbines have in excess of 10 blade rows, with each row consisting of a row of stators, or non-rotating blades, and a row of rotors, which rotate on the turbine shaft. Steam turbines need a large number of blade rows to extract the energy from the expanding steam because steam expands a lot as it drops in temperature. R-123 expands very little compared to steam, and needs only 3 turbine blade rows to extract most the energy from the Freon's critical point temperature of 184C and pressure of 532 psi down to 50C and 31 psi.

As a hobbyist, making a turbine with only 3 blade rows is much, much easier than making one with 10 rows.

Another benefit for me, as a hobbyist, is the calculated turbine nozzle exit temperature of 128 C allows me to use aluminum for most parts of the turbine, including the blades. Aluminum is much easier for me to machine compared to steel which would be required for higher steam temperatures.

 

[Steamchick]

Hi Toymaker. I understand why you are choosing R123 as a working fluid. The Entropy, Enthalpy and other data is included in the data sheet.
I have commitments all today, and most of the weekend, so I'll have a look at the sums next week for you. The simple aim is to produce an estimate of the surface area of coils you need to exceed to be sure you are getting enough heat from the burner exhaust gas. Your 9300sq.in. is probably OK, but I'll see what the numbers give.
As you are studying the thermodynamics, have you reached the "boiler" calculations yet? Or have you manually worked the calculations by hand (calculator, log tables, etc.) to figure out where you lost your factor of 1000? Maybe a K in kw? Or kg or similar?
K2

 

[ajoeiam]

My simple maths comes from K.N. Harris - Model boilers and boilermaking.
The standard Steam Tables are available anywhere on the net. But I used Harris as that was quicker than the web.
Essentially, if you have never eerie need the steam tables, the are a pre-computer device to quickly read the values for calculation.
Namely the enthalpy of steam, plus thermal capacity of water, plus the latent heat of evaporation - all combined into values that change with temperature and pressure. Tables save half the calculation, but you can find all the stuff if you enjoy browsing the erb. (Personnally, if there is a table in a book I find it saves time! The web is SO SLOW AND TEDIOUS, when you are familiar with other Old fashioned tools!).

Superheating. A bit of history.
Newcomen invented an engine where steam displaced air in a cylinder, which then was condensed and the latent heat removed so the ensuing vacuum allowed atmospheric pressure to drive the piston and the water pump. It didn't use the thermal capacity of watrr, nor any pressure of steam.
James Watt decided there was power in the steam, so while at low pressure, he used it to push on one side of the piston, instead of Newcomen's atmospheric pressure, as well as the vacuum of the exhausting side of the piston, to increase the pressure difference on the piston to incresse the efficiency of the engine. He also (like Eddisson and others) took all the ideas from others and experimented, finding the best of the options, and patented them which made him and his investors loads of money selling licences. Not a daft lad! His engines used both the steam-heat (as pressure) tuo push the piston, and latent heat (from the condenser creating sub-atmospheric pressure) "pulling" the piston. So a step forward.
Then Trevithic took steam at relatively high pressure, realising the true power of the energy in the steam as steam pressure to take a leap forward from large stationary engines to smaller mobile plant. Often ignoring the latent heat because he simply dumped steam out of the engine, instead of using the latent heat in a condenser.
Then later, - don't know when - someone realised the steam is simply a gas that holds energy - released when it expands. So the suprrheater was developed. This simply adds a lot more heat to the steam, so without increasing the "losses" from heating water from cold to boiling point, you can transfer a lot more energy in superheated steam compared to "wet" steam - which generates water droplets immediately it loses some energy. Superheating is all the heat gained by the steam AFTER it leaves the water zone and is heated further. This "Dry" steam is absolutely necessary in power stations in steam turbines, that cannot tolerate droplets of water at the sonic speeds achieved in the turbines. So these power plants cannot use the energy in the thermal capacity of water, nor the latent heat of water, but use the difference of the enthalpy of the superheated steam (pressure) into the turbine, and the enthalpy of the still superheated (dry) steam at the exhaust from the turbine.
Does that help?
K2

Thanks for the pointers and the info!!!!!!!!!

 

[ajoeiam]

Hi again Tia.
Do you want me to write the numbers with calculations on a sheet - for you to check an find my mistakes (I usually hide something really obvious in them - that I can't see!). I DON'T MIND. In fact I would appreciate ir. The use of a buddy check was standard practice in one design office where I worked, but it doesn't happen now everyone has computers to make the mistakes for them...
It will take a day or so.I can use your direct comma link until proven OK.
In my head, the relevance of these calcs is to compare real results for 150 kW between water and Toymaker's Refrigerant.
I.E. 4000sq.in. for water against 10sq.in. for refrigerant seemed wrong , but against 12000 sq.in. seems comparible, without knowing the thermal capacity of Refrigerant, latent heat and enthalpy of the vapour, and Toymaker's ideas of the various temperatures and pressures.

But sometimes my head goes off in the wrong direction, so I welcome all feedback from you.
Cheers,
Ken

Oops - - - tia - - - thanks in advance (grin!)

Right now I'm about up to my eyeballs in the alligator swamp.
The idea is to some time later (winter - - - I think) work through some stuff.

Thanks for the offer!!!! Sounds like a good idea.

 

[Steamchick]

Ajoeiam, it is only my interpretation of the history and Engineering. The things that fascinate me are those developed before the "Laws of Physics" - as we learned at school, were written.
Newcomen didn't know he was using atmospheric pressure on top of the piston, or the power of the latent heat of evaporation (that created the steam that he used to displace the air) beneath the piston, as those were "not on his school curriculum". But his engines powered mine water pumps for decades before Watt started to use the pressure of steam added to the atmospheric pressure. So he was harnessing the energy from both enthalpy and latent heat, which is where his genious idea lay, without knowing the modern Physics of what he was doing.
The question raised about Superheating in Power stations made me think of the way the turbine extracts ONLY enthalpy energy, as the exhaust from the turbine must remain as dry steam.
I really had not considered that before, so thanks again for the intelligent question.
K2

 

[Steamchick]

Toymaker, Ajoeiam, I shall write down the calcs soon, between busy life stuff.
K2