Regular readers of Biglorryblog will know I've been keeping a close eye on the activities of Turbine Truck Engines, the Florida-based company which is busy developing a 21st Century 'detonation-cycle' gas turbine engine for heavy trucks.
Well I've been contacted by BLB contributor Neil Temple who tells me: "Not sure if you're already seen this, but 'YouTube' has turned up some footage of a prototype from Turbine Truck Engines. Thought this might be of interest."
And it is Neil, it is. As you can see it's not that far off the typical dimensions of a normal heavy truck in-line engine and according to those in the know, the detonation cycle gas turbine is light-years ahead of the old '60s and '70s truck gas turbine power units.
Meanwhile, this is the first time BLB has seen the much-awaited TTE prototype in action. How long before we see it in a truck? Watch this space!
And in the meantime, click through to see what we had to say about TTE in 2006.
Here's the entry from June 2006:
Sometimes I wonder whether it's not only the same language that separates Britain and America... I have just received a press release from Deland, Florida-based Turbine Truck Engines Inc. which declares that following recent conversations with large fleet operators who have expressed a growing concern with high energy prices and high fuel consumption of their fleets, those same operators "have asked if Turbine Truck Engines can produce a 350 horsepower 'Flex-Fuel' Engine."Well, it doesn't look like we ever got that reply. We're still waiting, TTE!
Now I for one thought gas-turbines had gone out with the flood - but TTE insists its "new, energy-efficient Flex-Fuel Detonation Cycle Gas Turbine (DCGT) can be designed and manufactured, as a new or replacement engine for ALL heavy duty trucks that utilize engines ranging from 300--1000 horsepower." Hmmm, that's quite some boast.
TTE goes on to say its focus "Has been the 540 horsepower DCGT engine for heavy duty trucks. With that engine's basic design complete, TTE and Alpha Engines, Corporation are now able to continue work on designing other horsepower models of the DCGT engine."
Biglorryblog is intrigued to know how TTE has overcome the traditional drawback of gas turbine engines in trucks--namely they work fine when running at constant revs but use a lot of fuel and lose efficiency when operating across a constantly varying rev range as in your average truck. Which is probably why, despite a few high-profile prototypes like the Leyland Gas Turbine, Ford Big Red and Volvo Environmental Concept Truck (pictured above) the manufacturers have stuck with conventional diesel engines.The one time gas turbines DO become efficient is combined in a hybrid driveline when they run at a constant speed and power an electric motor, as in the Volvo ECT. But unless TTE have come up with a brand new mouse trap I don't see it changing overnight. Still, when US truck operators start griping about fuel costs, anything can happen...
Marc de Piolenc in Iligan City, Philippines has posted back the following comment to BLB:"Not that I necessarily believe TTI's claims, but they are not physically and economically impossible. The key is the phrase "detonation cycle." Continuous-combustion gas turbines are limited in peak pressure to the maximum compression pressure provided by the compressor. A detonation-cycle gas turbine uses resonant combustors that achieve a higher peak pressure, cyclically, more like piston engines than the turbines we're used to. That should make them both more efficient under ideal conditions and less vulnerable to a drop in efficiency at part load.
This is actually not new - it harkens back to the earliest attempts at gas turbines by the likes of Armengaud and Holzwarth, which used pressure-gain combustors to compensate for the then very low efficiency of flow-type compressors. The concept was recently revived to get around the thermal limits to gas turbine efficiency.
A fair amount has been published in the technical press, but I was not aware of any breakthrough. If TTE really have got a workable pressure-gain combustor, it's big news, and not just to truckers."
Meanwhile, BLB has e-mailed TTE for more information so stay sharp! As soon as I have more I'll blog it.