Archive for gas-turbine engine

Cyclone engine

Posted in Alt-Fuel, Car conception, Green Tech with tags , , , , , , , , , , , , , on 16/01/2012 by Alexander

I’ve covered gas-turbine engines before, and they still live on in my mind as one of the best alternatives to ICE’s. Not as a direct substitute, mind you, but as a compliment to EVs as range extending technology. It’s a rather elegant solution, since it allows for regular, fossil-fuel consuming folk to adjust more easily due to the fact that they still have to pump in fuel, while at the same time it’s a cleaner, more eco-friendly electric vehicle. Everyone’s happy.

Perhaps their greatest advantage is that they can run on nearly anything that burns. Petrol, diesel, kerosene, whiskey, perfume, basically anything that’s liquid and combustible. And that includes all sorts of lovely biofuels that hopefully will be produced just as cleanly as they burn. However, this application of gas turbines to automotive propulsion is only being pursued by a consortium (that includes Jaguar), apparently.

It even crossed my mind to do something I’ve dreamt about for years: to get myself an old car, rip out the engine and turn it into an alternatively propelled vehicle (just as these guys turned a classic Toyota 2000GT into a solar-powered EV). In this case, a gas turbine electric hybrid. And I thought to myself, how hard can it be?! You just remove the ICE and strap in a gas turbine, batteries and some electric motors behind each wheel hub. But I’m absolutely certain that in reality things would be much more complicated than it sounds. The most elementary components that have a clear place in a conventionally-powered vehicle could become a nightmare. How many gears would it have, if it even had gears at all? What would power the brake servo, the air-con, or the rest of the HVAC system? Would it be the turbine or the batteries? How would someone who wasn’t a very clever engineer even begin to rig the readouts as to how much juice you have left on the batteries, what shuts down or comes to life when the turbine kicks in, etc., etc.? That’s complicated s**t.

I’m still curious as to how gas turbines compare with regular engines. I can’t seem to find any sort of specifications as to what mileage you could get from a gas turbine electric hybrid car or what’s their emission-per-km figure. After all, it’s a very nice technology in principle, but not really worth it if takes a gallon of fuel to keep the car fully operational for a mile. The Jaguar C-X75 concept has “an estimated fuel economy of 41.1 mpg, 778 horsepower, 0 to 62mph in 3.4 seconds, and a top speed of 205 mph”, which is very nice for a concept car, but that doesn’t mean it can to it in the real world. While trying to find some proper numbers, I stumbled across yet another type of engine I wasn’t aware of, called the Cyclone Engine. Its working principle is (if I’m not very much mistaken) a modern take on the steam engine, and has many real world applications, not just powering cars. And like the gas turbine idea (and unlike the split cycle engine and, from what I can tell, the shockwave motion generator), it can burn virtually anything in order to function. The website boasts a lot of advantages over conventional internal combustion engines, just like the split cycle and shockwave engines, from efficiency to number of components, which makes me wonder why these sorts of things aren’t being pursued more aggressively by more mainstream car manufacturers. If any one of these technologies (or hopefully, all of them) take hold, they’ll be tripping over themselves to play catch-up.

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Gas-turbine engines

Posted in Alt-Fuel, Car conception, Green Tech with tags , , , on 07/07/2011 by Alexander

Jaguar’s scrumptious recent concept, the C-X75, was a celebration of its 75th anniversary, and apart from being rather pleasing to the two forward-facing orbs in our heads, what made it move was also rather cool: four electric engines that could be charged by gas turbines, which in turn can basically run on anything flammable. These sorts of engines are nothing new, and are basically what power jet aircraft through the sky, and their application to cars is older than strapping turbos onto them.

Like GM and the electric car, Chrysler was the company responsible for squandering the opportunity to make something worthwhile regarding gas turbine engines. After development during the 50’s and 60’s, with continual improvements, Chrysler launched 50 prototypes on a 3-year experimental program, which sought to evaluate all the pros and cons of this proposed means of propulsion.

One out of four drivers complained about gas guzzling (they must have been out of peanut oil), and one out of three groused about throttle lag. But there was also plenty of praise, especially about the vibration-free operation and snazzy styling.

Though Chrysler never released one to a journalist, writer John Lawlor managed to drive a Turbine Car toward the end of the consumer test. He, too, was impressed by its smoothness, but annoyed at the relative lack of engine braking — and at the throttle lag, which he reported as the claimed 1.0-1.5 seconds.

His mileage also disappointed — just 11.5 mpg — though he usually ran on cheap kerosene. Lawlor did laud acceleration, which at under 10 seconds to 60 mph was sparkling, especially for a 4,100-pound car. So much for rumors that turbines couldn’t be quick.

Unfortunately, car companies love to trash experimental vehicles en masse when they’re done with them (see GM EV1), with very few surviving examples (one of which now owned by Jay Leno). Development continued into the 70’s and early 80’s, until cuts in federal funding (the Department of Energy was providing Chrysler the lolly to develop the engines) and emissions standards (there was trouble keeping nitrous oxide emissions low) and the ominous spectre of bankruptcy for Chrysler looming on the horizon (that sounds familiar) killed hopes for a production model.

It’s unfortunate things ended when they did. According to one project official, left stillborn was an eighth-generation turbine designed, ironically enough, for Chrysler’s all-important new front-drive K-car compacts and their future derivatives. With a single turbine shaft (versus two), electronic fuel delivery, and a projected 85 horsepower, it would have been the simplest turbine yet, and likely the cheapest to build in quantity.

There were also hopes that a new variable-geometry burner would be the long-sought answer to NOx. But time and money had run out, so this engine went no further than blueprints and a foam mockup.

And since then, the technology has advanced even further. So this begs the question: why is no-one placing their bets on the gas-turbine horse? I suppose it would help to list the various advantages/disadvantages to help the layman (such as myself) see what’s involved:

Advantages of gas turbine engines

  • Very high power-to-weight ratio, compared to reciprocating engines;
  • Smaller than most reciprocating engines of the same power rating.
  • Moves in one direction only, with far less vibration than a reciprocating engine.
  • Fewer moving parts than reciprocating engines.
  • Low operating pressures.
  • High operation speeds.
  • Low lubricating oil cost and consumption.
  • Can run on a wide variety of fuels.

I believe the advantages speak for themselves, so let’s scrutinise the disadvantages and see how could they be overcome:

Disadvantages of gas turbine engines

  • Cost – Nothing mass production wouldn’t take care of. Besides, Mercedes and BMW’s are expensive, and people still buy them.
  • Less efficient than reciprocating engines at idle – Solve it the Jag way, i.e., use it to power electric motors, so instead of having it functioning when stopped at a traffic light, use the electric motors for starting up, and allow the turbine only to kick in while in motion.
  • Longer startup than reciprocating engines – See above.
  • Less responsive to changes in power demand compared to reciprocating engines – Again, use the electric motors for the immediate response.

(taken from here)

There. Problems solved.

No, seriously. There might be some pretty big flaws in my proposed solutions, but I’m convinced these things can be overcome (or could already be solved, had the gas-turbine engine been continually developed). Another serious impediment is that all the copyrights and patents are probably sitting in a Chrysler vault gathering dust somewhere. And I doubt other car manufacturers are willing to spend wads of cash licensing the tech when they already spend zillions in developing their own conventional ICE’s.