|A rendering of a 540hp prototype.|
A Florida company, Turbine Truck Engines (TTE), is developing an implementation of a multi-fuel turbine for heavy-duty vehicle applications, and has recently completed the design of a fifth, 540hp prototype.
The Dentonation Cycle Gas Turbine (DCGT), originally developed by Alpha Engines beginning in 1984, promises to consume 30% less fuel; to emit fewer criteria pollutants (NOx, CO, HC); and to emit fewer greenhouse exhaust gasses than current piston engine technology. The turbine operates on all hydrocarbon, hydrogen, and synthetic fuels. The DCGT has Flex-Fuel and mixed-fuel capabilities, as well as cold start capabilities with any fuel.
TTE was formed in 2000 to acquire the engine technology and license rights from Alpha Engines. Alpha Engines Corporation remains as a privately owned research and development company.
|Cross-section of the DCGT|
The engine includes a turbine rotor contained within a housing. Exhaust ports of paired valveless combustion chambers are located on opposite sides of a rotor, which operates in a manner similar to a water wheel. Combustion gases exit the combustion chambers via nozzles, and spin the turbine rotor.
A valveless manifold fed with fuel and oxidizer connects the combustion chamber pairs. A blower, rather than a compressor, supplies low pressure air via the single manifold. When the air-fuel charge ignites, the back pressure from the detonation shuts off the charge flow to the active chamber and redirects the charge to the opposite chamber for the next detonation. The process repeats cyclically. The rotor shaft can provide mechanical power directly, or be used to generate electricity as a genset in a series-hybrid application.
The engine uses a fuel pump and vaporizers to gasify wet fuels prior to mixing with combustion air in the manifolds. The engine uses a plasma arc ignition (Electromagnetic Isothermal Combustion—EIC), a visibly constant illuminating plasma flame between two electrodes to detonate fuel-air mixtures and does not require critical ignition timing.
TTE claims that the almost instantaneous ignition of the low-pressure air and fuel mixtures produces high velocity shock waves that kinetically compress inert gases resulting in higher working pressures than the pressures produced in constant pressure heating utilized in gas turbine engines, and Otto and Diesel cycle piston engines. The EIC process also produces complete combustion of fuel-oxidizer mixtures in cyclic detonations that reduce emissions, according to the company.
As a result, the company claims, the detonation cycle engine uses less working fluid and produces less exhaust gas per horsepower hour than Brayton cycle turbines and Otto or Diesel cycle piston engines.
The EIC process enables the DCGT to operate with blower air at low static pressure, negating the necessity of compressing and preheating fuel-oxidizer mixtures prior to combustion. By eliminating the compression of fuel-oxidizer mixtures, the DCGT achieves higher thermal efficiencies in a simplified mechanical structure, according to the company.
In addition to the fifth design prototype, Alpha had developed four working prototypes:
1987. The engine consisted of one 8-inch diameter, 26-pound turbine wheel, driven by two horizontally opposed combustion chambers. The engine produced 78 horsepower at 12,500 rpm.
1989. The engine consisted of two 5-inch diameter, 11-pound turbine wheels mounted on a single shaft, driven by four horizontally opposed combustion chambers. The engine produced 130 horsepower at 14,000 rpm.
1991. The engine consisted of two 7-inch diameter, 19.6-pound turbine wheels mounted on a single shaft, driven by four horizontally opposed combustion chambers. The engine produced 256 horsepower at 8,300 rpm.
1997. The engine consists of four 6-inch diameter, 12-pound turbine wheels mounted on a single shaft, driven by eight horizontally opposed combustion chambers. The engine produces 130 horsepower at 8,400 rpm. This engine is currently used for demonstration and can be seen by appointment.
Working prototype #4. 1997.
The fifth design prototype has six 15-inch diameter, 20-pound turbine wheels mounted on a single shaft, driven by 12 horizontally opposed combustion chambers producing 540 hp at 3,000 rpm.
TTE last week announced that it is discussing a potential joint venture with a $5-billion worldwide transportation company to manufacture heavy duty highway truck engines.
Videos of earlier prototypes.
- US Patent #6,000,214: Detonation Cycle Gas Turbine Engine System Having Intermittent Fuel and Air Delivery