High torque engines

well there you go then ...when these posts get over a page long often the confusion sets in in the readers mind ....good luck with it

 

ten pages is about my limit
after that the attention deficit sinks in and I have to come back to it
best
B
and hey
how did you like the boiler idea
turns out pellets are less than half the cost of the diesel pr btu
and everything including the lack of transmission is a huge savings
no gearing necessary and the steam is recycled
engines are about half the cost

Im working on stacking the boilers one on top the other so as to use the preheated exhaust gas of the boiler underneath to assist with the boiler above I can increase efficiency by I think about 20% that way but I need to work it all out
its kinda my next thing to work on but I need to complete the diagrams first

fun fun fun
B

 

pistnbroke

You can lead a horse to water....

 

If it's steam you want, maybe you should look into a steam engine that runs at higher speeds to begin with.

http://www.greensteamengine.com/licenses.htm

They are also very light weight and compact and look very easy to build, with surprisingly few parts to machine from stock.

Jimbo

 

without looking it up
can anyone tell me the substitute value for 12 if your calculating for a hip or valley rafter on say a 6/12 pitch


NUP, we are boatbuilders not bloody house builders, why would we want to pitch a roof on the boat? We use CAMBER.

 

Hey Jim
I looked at those early on in my search for an engine type.
The acentric engine designs have a lot of advantages as you pointed out, but they have one huge disadvantage, however, it's obvious when you think about it, they impart huge vibrational forces the there surroundings. The high speed attempts to counteract that but that would mean I'd need a transmission and that's kinda one of my favorite parts to the low speed engines, with the 0-1500 rpm reversible engine being perfect for low speed high efficiency shrouded screws.

Turns out its not the engine thats the tricky part. The have had those down for years, its the boiler thats were you win or loose the game. Looks so far like a monotube boiler running on pellets is only available as a low pressure home system

Landlubber
got you on that one eh

cheers
B

 

Boston,

You've hit on the chief advantage for the Greene engine; it operates on ridiculously low pressures and still maintains practicality. His engines will make useful power as low as 2 psi. If you want more power on less pressure, you simply install bigger pistons. This greatly influences boiler design, certification standards and cost, obviously.

Jimbo

 

Ill go give em a second look
but that vibration looks like a frame killer to me

the lower pressure was why I was looking at em in the first place
but they dont look all that reliable to me with that wonky spin they have
seems like it would shake itself apart

 

Boston:

My engineering education occurred right during the transition between metric and imperial - early courses used metric units and the later, more specialized engineering courses were still in imperial units. Coincidentally, the slide rule disappeared in the same time frame, and hand-held calculators were introduced and became programmable during that time period. Anyway, to the point...

In your posts #37 and #42, it is apparent that you are(were?) confused regarding Rick's use of the units of "N" for Newtons, and "n" for rpm (revs/min, or 1/min), and you are assuming that those n's are the same units - they are not....
n (small case n) is a variable that is expressed in the units of 1/min (revs/min, rpm) and is a measure of rotational velocity.
T (thrust) is a variable (calculated result) that is expressed in units of N (upper case N, for Newton(s)), and is a measure of force - equivalent/proportional to the imperial units of lbf (pounds force), poundals, and slugs.

So in those posts, you are confused (rightly so) on how to convert thrust to RPM.

Please note that it is metric convention to use capital letters for units named after a person ie, Newtons, Watts, Joule, etc.., when you look at Rick's prop summaries, you will see he uses kW for kiloWatts. And it is also convention to use capital letters to indicate calculated values ie: Ricks use of the captital "T" for thrust.

Having lived on the fence between metric and imperial systems for the past 30 years, I've had to understand and use both systems, and deal with the people that are entrenched in both camps.
Really, it is a matter of carrying the units and making sure that it all makes sense, and understanding what the metric "named" units are.

I hope that helps, and doesn't confuse the issue.

Another Jim.

 

my god I remember slide rules
when I started school I was kinda the idiot savant and ended up in all the higher math classes
the testing process was usually no calculators but slide rules were ok

metric kills me
I know its a better system and once you know it its easier
but
I dont know it very well and hardly ever use it
I do with that the usa would convert to it though
it is easier being base ten instead base anything
thanks
I didnt know about the big N little n

it clearly kicked my ***

glad you noticed

cheers
B

recently picked up two jobs
I have one I'm volunteering at that Im hoping hires me ( fingers crossed its at a very prestigious establishment, they chose about 30 of about 6000 applicants for this position )
its with a bunch of scientists and biologists who work exclusively in metric
the other is exactly the opposite and the guys there would shoot me if I tried to interject anything even sounds like metric

 

anyone ever heard of a stirling engine

thing leaves the water part out of a steam engine
and just runs on the thermal expansion and subsequent contraction properties of superheated air






so far it looks like it wouldnt put out enough power but its got style

 

Any idea what materials (metals) are being used.

 

nothing spectacular just aluminum and copper is what it looks like

if they were to stick an ice cube on the top of the cold side cylinder it would run like a banshee

Im just not convinced it can be made to pound out any torque

 

Stirling engines are quite old yet still maturing. A type of Swedish military submarine uses a Stirling engine. Stirlings boast the highest thermal efficiency of any engine type, and can have nearly perfect Carnot cycle efficiency. Their chief disadvantage is poor weight to power ratio. A big advantage is that they are external combustion engines so they can burn anything, or even use a non-combustion heat source, like solar. Also, the inevitable engine degradation from combustion by-products simply does not happen, so they are very maintenance free. With no periodic explosions going on or high pressure gases venting, they are also eerily quiet.

Jimbo

 

The performance of the engine can be calculated a P-V diagram. The volume in the engine is easily calculated by using the internal geometry. When the volume, mass of the working gas and the temperature is decided, the pressure is calculated using an ideal gas method as shown in equation (1).

(1)

The engine pressure can be calculated under following assumptions:
(a) There is no pressure loss in the heat-exchangers and there are no internal pressure differences.
(b) The expansion process and the compression process changes isothermal.
(c) Conditions of the working gas is changed as an ideal gas.
(d) There is a perfect regeneration.
(e) The expansion dead space maintains the expansion gas temperature - TE, the compression dead space maintains the compression gas temperature - TC during the cycle.
(f) The regenerator gas temperature is an average of the expansion gas temperature - TE and the compression gas temperature - TC.
(g) The expansion space - VE and the compression space - VC changes according a sine curves.

Table 1 shows symbols used the Schmidt Theory.



http://www.bekkoame.ne.jp/~khirata/academic/schmidt/schmidt.htm

the real question Jim is
who has a working model of a man sized Stirling engine and or plans for sale of same along with performance data


oh
they are not that quiet
those valves seem to make quite a racket in the videos

and what is the power to weight ratio
cause if I went with this type of engine I would not need boilers ( boilers of the size needed for the engines Ive specified weigh 350 lbs each dry
and I need three of em for engines that only weigh 250 lbs each
ttl weight of the typical steam engine and boiler group that I would need 1550 lbs with a ttl of 250 hp at absolute max and more like 180 ttl sustainable hp
or 8.6/1hp not including water or all the condensation systems

so the constraint of poor power to weight ratio may not be so bad if I knew what it was