[Gasification] Fw: Underwater gasification?

[Mark Ludlow]

Where do all of the combustion by-products (tars) go?

The hull speed will likely be significantly less than the velocity of the
water jet. Lots of water movement; not much momentum transfer to the hull.
Not all fuel burned is converted into propulsive energy. Viscous friction
and turbulence eats a good fraction of it. Galley Slaves may be more
efficient.

Dosidicus gigas, the Giant Humboldt squid, propels itself by "jetting'
around. It is the least energy efficient of all sea creatures in terms of
motivation and it's had eons to perfect its propulsion system.

Mark

-----Original Message-----
From: gasification-bounces at lists.bioenergylists.org
[mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of Rolf
Uhle
Sent: Thursday, May 26, 2011 9:41 AM
To: Discussion of biomass pyrolysis and gasification
Subject: Re: [Gasification] Fw: Underwater gasification?



But it must have a big volume of pressureproof vessel inside the hull.
And if I calculate it right, the Humphrey pump delivers some 260
net kW. No idea how high it's efficiency is, shure not 100 %!
Neither how efficient a jet propulsion like this could be.
 But even 260 kW are not much for a big ship with a huge vessel inside.
ICE's compress the air much more and have a higher energy density.
Sometimes beauty and virtue don't go the same way !

Rolf

Am Donnerstag, 26. Mai 2011 17:13:30 schrieb Henri Naths:
> ps
>  I think the beauty of the a Humphrey-inspired water jet is that it would
>  have relatively no moving parts so it's weight to  power ratio of

>  efficiency is better than that of other engines overcoming the friction
>  losses of a conventional water jet engine (as per water ski) H.
> ----- Original Message -----
> From: Henri Naths
> To: Discussion of biomass pyrolysis and gasification
> Sent: Thursday, May 26, 2011 8:57 AM
> Subject: Re: [Gasification] Underwater gasification?
> 
> 
> Hi Daniel,and list
> <  I don't think it would be an efficient means of low speed marine
>  propulsion though; it would suffer from low propulsive efficiency because
>  the jet velocity would be too high.> Have you considered the propulsion
>  end of a jet ski or a Jet Boat in your analysis . True the efficiency is
>  slightly lower than a straight prop boat but it is expelling a relatively
>  small stream of water at a high velocity. I hear what you are saying
about
>  the jet engines  but as I previously pointed out in a post , water has
700
>  times the density than that of  air so you have to factor that in the
>  formula. Thanks
> Henri
>   ----- Original Message -----
>   From: Daniel Chisholm
>   To: Discussion of biomass pyrolysis and gasification
>   Sent: Sunday, May 22, 2011 5:51 PM
>   Subject: Re: [Gasification] Underwater gasification?
> 
> 
>   A Humphrey-inspired water jet is an interesting idea.
> 
> 
>   FWIW I don't think it would be an efficient means of low speed marine
>  propulsion though; it would suffer from low propulsive efficiency because
>  the jet velocity would be too high.  The efficiency of a reaction engine
>  (which is something that generates thrust by accelerating and expelling
>  mass - a very broad category that includes not just jet and rocket
engines
>  but also propellers on aircraft and ships) depends on the speed at which
>  the mass is expelled.  Accelerating a small mass to a large speed, is not
>  as efficient as accelerating a larger mass to a lesser speed.  If you
look
>  at aircraft jet engines today (high bypass ratio turbofans) you will
>  notice that they are much larger in diameter than the jet engines of the
>  1950s (turbojets) - this is why.
> 
> 
> 
> 
> 
> 
> 
>
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