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 Gasser Math

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tritowns



Posts : 267
Join date : 2013-12-03

PostSubject: Gasser Math   Fri Dec 06, 2013 12:49 am

here is some traditional imbert gasifier math from gasser guru Dutch John

calculating gas required to run an engine...


G = V x n x 0.5 x 0.48 x 0.72 [l/s]
                       60

G is the needed quantity of gas in liters per second
V is the engine displacement in liters
n is the rpm
0.5 is the four stroke factor
0.48 is the mixture composition (1: 1.1)
0.72 is the filling degree of the engine (assumption)
60 for the conversion to seconds

DJ's volvo example

Example: G = 2.32 x 2,750 x 0.5 x 0.48 x 0.72 = 18.4 [liter cold gas per second]
                                           60


calculating the restriction


d = square root from (4/pi x G/Vi)

d is the restriction diameter
pi is 3.142
G is quantity of cold gas per second
Vi is the superficial velocity being: 2.5 [m/s] = 25 [dm/s] for an Imbert


Example: d = square root from ((4/3,142) x (18,4/25)) = 0.97 [dm] = 97 [mm]


from this you can calculate the rest of the dimentions



all of that should get you in the ball park.

I build what i consider a modified imbert so I usually calculate restriction sizes and use that as my starting point.
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ppotty1 Admin
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PostSubject: Re: Gasser Math   Fri Dec 06, 2013 4:36 am

Im sure it makes sense to you mate im afraid it's whoooshhhhhhh over my head :lol: I think my head its too full with other stuff so I got to leave room for updates to stuff I already know ....well that's my excuse ;) 
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tritowns



Posts : 267
Join date : 2013-12-03

PostSubject: Re: Gasser Math   Fri Dec 06, 2013 5:54 am

lol... it used to be over my head too....

i learned all that so one of my mentors could show me short cuts.

G is the needed quantity of gas in liters per second
V is the engine displacement in liters
n is the rpm in thousands of rpm

like G = V in liters x n in thousands x 3

so for calculating for my pickup truck

G = 5 x 2 x 3

G = 30 L/s of woodgas

and from that i can then calculate the restriction needed. i made a spreadsheet to help with math one day at a trade show... i hate math.
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T2H
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PostSubject: Re: Gasser Math   Sat Dec 21, 2013 1:24 pm

Too funny tritowns, your telling my life man, however I can see once you have the formula down it actually is quite simple.

The problem for most of us is grasping the formula, I appreciate you sharing it and as well describing how to understand it, once you have a firm grasp on the formula the rest is history and a lot of hard work and fabrication eh?

I do appreciate your thoughts on the subject matter and thanks for sharing them.
I am hoping to do a build this summer, just too darn cold out right now.
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T2H
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PostSubject: Re: Gasser Math   Sat Dec 21, 2013 1:26 pm

So what we are looking at here is how to formulate the amount of gas to produce at a given engine displacement and rpm rate.
So the rpm rate is the expected demand rate correct?
I find this very exciting.

A whole new world!:>)
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tritowns



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PostSubject: Re: Gasser Math   Sat Dec 21, 2013 1:52 pm

yup. you design for the average you intend to use. for a stationary system this is/is not hard to do. automobiles are a little more complicated.

there are lots of other things to take into consideration.

when i'm building a system i look at handling condensates, hearth insulation, handling ash, air preheat... in that order. and thats just the gasifier... filtering and cooling need to be taken care of.
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T2H
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PostSubject: Re: Gasser Math   Mon Dec 23, 2013 4:06 pm

Again thanks for the formula and the great diagram, will have to study this well.
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