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Propulsion Technologies + Technical Issues ...

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#1 engware


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Posted 06 July 2006 - 09:44 PM

To All:

I would like to invite both Forum members and visitors to start a discussion on Propulsion Technologies and Technical Issues -- ask questions of interest, share knowledge and experience related to Propulsion Technologies and Technical Issue (both automotive and aviation propulsion technical performance (fuel and technology -- hydrocarbon, hydrogen, biofuel and internal combustion, gas turbine, fuel cell), modeling, operation, maintenance and commercialization issues can be considered).

Also, everybody is welcome to contribute to the Propulsion Technologies and Technical Issues topic.



Below are a few plots dealing with the Brayton Cycle (Gas Turbine).

#2 djack77494


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Posted 13 August 2008 - 05:34 PM

The field of propulsion technologies is a very broad one with many widely differing options. One area that I have always found to be of interest is the use of magnetohydrodynamic propulsion. This interesting technology, which was never commercially developed, is simple in theory yet difficult in implementation. It can be used to power things as diverse as a slow moving submarine (a la the movie "Hunt for Red October") or as fast as high speed railgun weapons. I think of it as the linear cousins of the rotating electro-mechanical devices currently in widespread usage. Interesting, no?

#3 engware


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Posted 13 August 2008 - 07:10 PM


Thank you for your post.

You are right about MHD and its applications.

MHD can be used for both power and propulsion generation purposes by using different fuels and working fluids in various configurations. Many, many possibilities ...

On paper very simple and easy, but implementation and commercialization are still far away ...

As a matter of fact, for almost ten (10) years, I paricipated in a U.S. DOE MHD program that was based on using coal as the fuel when generating plasma. Due to the lack of significant expermental work progress, lack of additional funding and support for MHD and change of scope regarding U.S. DOE fossil fuel programs, the MHD program was just shut down. Worldwide, there are very little ongoing Government sponsored MHD research activities and work going on at the present time ...

As you can imagine, I was involved in the analytical and computer modeling of MHD combustion and MHD channel modeling.

Now, in my spare time I try to share with the engineering communities just the basics of energy conversion with those interested ...

I do read your posts and I do like them. It is my pleasure to have a chance to meet you over the Internet.



#4 djack77494


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Posted 14 August 2008 - 04:23 PM

Thank you for your post and what a surprise. My exposure to MHD was a bit stronger than merely finding it to be a technology of interest. We must have worked within the same DOE program - development of coal-fired MHD (electric) power generation. I worked at the CFFF facility but mainly in testing and downstream/bottoming cycle development. It was interesting how the program survived so many years of zero budget submittals during the Reagan/Bush#1 years. Each time the Democratic Congress re-funded the program that the Republican Administration had gutted. Until Clinton. He managed to do what the Republican president could never do - scrap the program. I always felt that the program should have focused on gas-fired power generation. Certainly would have been a lot easier to do than coal-fired. Ultimately, I think the mountain was just too darn big.

Interesting "talking" to you,

#5 engware


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Posted 14 August 2008 - 06:33 PM


It is a small world.

So if I am not mistaken, you must have worked at UTSI in Tennessee.

I live in Washington, DC metropolitan area -- Germantown, MD. Therefore, I had a chance to help out the US DOE Fossil Energy Office. My focus was on the topping cycle.

UTSI people would come to the SEAM meetings etc.

Doug, looking back and knowing what I know now, I do agree with you more than 100%. Having gas fired operation would have been better for the success of MHD and its proof of concept and eventual commercialization ... However, in order to get the initial funding approved and idea going, coal fired operation was the way to go ... Unfortunatelly, it just never turned out to be a promising path -- too complex, expensive and difficult ...

Programs come and go ... Somehow people survive and get back together in a strange way. Engineering helps them prevail ...

Good programs and good engineering stuff and, in my opinion, it is just sad that such programs never get a chance to fully take off ... -- the good thing is that experience and knowledege go with the people and somehow get applied in another way and shape down the road ... It is good to get second and third chances in life!

Doug, if I may ask you, how did you end up in Alaska?

Well, it is good to know you. If I can be of any help to you, please let me know.



#6 Guest_awalshe09_*

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Posted 27 July 2009 - 06:30 PM

Here's a simple one I'm curious about but I'm not savvy enough to do the math for at the moment.

Mazda's RX-8 hydrogen/gasoline hybrid used to get only a 100 Mile or Km range from their 5000 psi hydrogen tank and was only able to generate 105HP from their hydrogen while the same cars gasoline engine would produce over 250HP and a much more suitable range. Mazda found that instead of using hydrogen combustion to directly power the wheels that they could double the range of the hydrogen tank by burning the hydrogen fuel to power an electric motor instead of powering the wheels directly via hydrogen combustion. I'm sure the high low end torque of electric motors helps. Even better to have that in combination with the high revving rotary gasoline engine. Electric motors are more efficient at lower rpm's while the rotary engines are more efficient above 4k rpm's.

Alright, so burning hydrogen to generate electricity allows them to go twice as far with more HP than burning the hydrogen to drive the wheels directly does.

So how much power is this hydrogen combustion generating? How much power is the car using to use up a 5000psi tank of hydrogen over 200 miles. (assume highway speed for todays purposes)

Then consider - how much does a portable diesel generator weigh? What is its overall power output vs how much fuel it uses? And what happens if we use a diesel generator to power an electric motor? How does this compare to the same amount of fuel being used in an equivalent weight diesel or gasoline engine vehicle?

I would love to hear some thoughts and see some math on this one.

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