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Ultimate flex

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The GreencarCongress post appears to be a copy of a news release. One of the comments following seems to suggest impossibility of efficient micro turbine? Well, yes leakage rate will affect small turbine more, true, but appears these guys not up on latest technology. The expensive alloys and air plume cooling not required for ceramic material. Also, high pressures temperatures a reality with ceramic material. So, as usual a moving target of technological improvement. The sealing is job number one for small turbines. The foil air bearing a big help as well as computerized fluid dynamics design software. They have software specific to hot air turbine design. 

 

Israel currently already has the best ceramic cutting tools for machine tool. Machine tool changed to ceramic as better choice as compared to tungsten carbide. Like turbine parts, cutting tools suffer from max heat and strength challenges. Ceramic beats carbide by 10x and cheaper.

 

Another micro turbine competitor Wilson Microturbine uses three stages to improve performance and raise the overall microturbine efficiency to 50% — well above the performance of any previous microturbine.

 

Up to 98% efficient, long-life, ceramic-core regenerator

The high heat-transfer efficiency of the Wilson Heat Exchanger results in a lower optimum-cycle pressure ratio to permit a lower blade speed of the ceramic rotors. And because the ceramic core of the heat exchanger transfers more heat and permits a much higher operating temperature than conventional metal-core systems, it contributes more thermal energy to preheating the inlet air.

 

Wilson claims In many regions, the microturbine will be able to generate electric-only power at a cost less than local utility rates. And in some high-rate locations, the microturbine has the potential to generate an annual IRR up to 200%. Using the heat recovered from the microturbine engine to meet onsite hot water and heating/drying needs can create a total system efficiency up to 90% to deliver even greater economic value.

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I’ll wrap up my thoughts, the subject post is old and long.

 

Micro-turbines could be a possible popular replacement for auto engine, but only in the electric hybrid venue. The technology seems ripe i.e. ceramic material, manufacturing capability/accuracies, and engineering analysis software. The technology is attracting lots of government and private sector R&D money. The basic technology well understood and developed and on a continual design improvement trajectory. The turbine incredibly simple, maintenance free, and durable. It’s pollutants minimal, minimal noise, and much less weight. Thermal efficiencies touted at 50%. This is upon estimates of pretty good analytical thermal analysis as the field has much experienced with proven analytical tools. This is not a new invention. Now, this is better efficiencies than most all engines, except maybe the special condition and untested machines. Maybe someday a linear stroke engine, or practical Sterling, but, even upon the theory of these engines; hard to beat 50%. Know the battery car not as efficient because of 10-15% line energy waste and 10-15% battery charging and uncharging waste.  So, a 20% overhead to begin, know those utility steam turbines upon the most efficient of critical steam operation are somewhere in the high 30 to low 40% efficiency. Nothing currently operating as efficient as hot air turbine engine.

 

The efficient turbine hybrid would appear not like the Volt plug in my estimation. Instead, best to utilize as much generation power as possible for propulsion and utilize the battery to even the consumption of power to steady state. 

 

The turbine hybrid hot exhaust could be utilized for thermal battery energy storage within the car, utilized for home use. Also, the power unit of car could make an very efficient electrical generator about 90% with utilization of thermal for hot water and space heating. Did I mention the engine can run on wide variety of fuels…the ultimate flex.

 

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Obormot,

 

the horizontal bar with lights on the dash is a GPS guidance system.  The pilot simply pushes a button on the stick at one end of the field, and flies his first pass over the field, then clicks it again at the end of the field.  It automatically plots a line 50' (or what ever the appropriate width of the spray boom is) for him to line up on for the next pass.  If he strays more then 12" to the left or right the light bar will flash telling him which way to correct to.

 

I used to (in high school) work for an arial spraying outfit.  My job was to drive the "flagging truck" which had a large (4'x4') yellow flag on the box that stuck up 10' for the pilot to line up on.  I had a flag attached to a hose clamp that fitted onto the hub of the front tire.  When the pilot would click the mike twice (the signal), I'd accelerate like mad, with my head out the window, counting 15 revolutions of the flag on the hub (50'), then slam on the brakes...  If I wasn't quick on the draw/count, I'd get a strong wiff of parathyon >:( (evil stuff!).  The pilot after he "acquired his line" would fix on a target on the opposite side of the field (tree, power pole, farm...) and try to fly strait to it.  At that end he'd push a button that shot out a flag, which is a 12' strip of toilet paper attached to a cardboard weight.  This would drift (hopefully not too far) down.  He'd turn around, find the flag, and line them (my flag and the toilet paper one), then signal me to move forward...

 

As you could guess, not that accurate.  I remember riding with my dad in the combine and finding these long wobbly swaths through the field where the corn boers obviously were not affected by the spray...  Sprayers that got a reputation for this were not very well looked up on by farmers.

 

When they started mounting GPS systems on planes (we got ours for the summer of '94) it was amazing.  Perfect lines, never got gassed by drifting chemicals... I got to sleep at the hangar 8), and wait for the plane to come back, and help load chemicals, water and fuel...  The pilot loved it as well.  Ahhhh technology!

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Orbormot, This spray outfit came to Iowa from Arizona last summer. They had two Air Tractors and two Thrushs. Those are Thrushs in the picture. The other nice thing about the GPS is you can do opposite sides of the field in a race track pattern so you don't have to make such tight turns. Say a field has 20 passes, you can do pass 1 and skip over to pass 10 and it will still work out perfect.

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cessna is correct, the opposite side of the field or "race track" method is the most efficient.  Quick quarter turns rather  long looping 180 turns.

 

They used to do this with the old "flagger truck" method, but that required having 2 flaggers (2x the labor), or having a 4 wheeler that rolled out of the box of the truck... We didn't do that, as it was not cost effective...

 

Add the GPS unit, and the racetrack method is used on all but the smallest fields.

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