Updating the Steam Engine: the Cyclone
4 April 2006
|An application of the Cyclone.|
Cyclone Technologies LLP, developer of the Cyclone external combustion engine, received an Automotive Engineering International (SAE’s publication) Tech Award at the SAE World Congress in Detroit.
The Cyclone modifies the traditional Rankin cycle steam engine to deliver the use of super-critical pressure (3,200 psi) and super-heated steam (1,200° F)—normally found in high-efficiency electrical power plants—in an efficient, compact package suitable for a vehicle.
|A sketch of the engine from the patent application.|
The Cyclone. The engine, which uses water as both working fluid and lubricant, consists primarily of a condenser, a steam generator and a main engine section having valves, cylinders, pistons, pushrods, a main bearing, cams and a camshaft.
Air pre-heated in a heat exchanger is mixed with fuel. An igniter burns the fuel charge as the flames and heat are directed in a centrifuge within the combustion chamber.
The combustion chamber heats the steam generator to produce high-pressure, super-heated steam.
A rocker and cam design which serves to open and close a needle type valve in the engine head controls the speed and torque of the engine. When the valve is opened, high-pressure, high-temperature steam is injected into the cylinder and allowed to expand as an explosion on the top of the piston.
Exhaust steam is directed through a condenser, in a centrifugal system of compressive condensation, consisting of a stacked arrangement of flat plates. Cooling air circulates through the flat plates, is heated in an exhaust heat exchanger and exits into the furnace. This reheat cycle of air greatly adds to the efficiency and compactness of the engine.
Efficiency. The efficiency of the Cyclone is based primary on three factors:
Heat Regeneration. Numerous design innovations significantly reduce the heat losses, cumulatively increasing the efficiency of the engine.
Super-Critical Liquid. Pressures in the range of 3,200 psi with temperatures of about 1,200° F cause super-critical vapor to act as a fluid. Maintaining the super-critical pressure, in the centrifuge process, eliminates the turbulence, backpressure events, and heat spikes that can occur during other less efficient types of super-critical processes. At these higher temperatures and pressures, the super-critical fluid carries more heat energy to the motor it powers. The Cyclone Engine is a piston engine with a special valve mechanism allowing it to operate at fluid pressures, thereby gaining multi-advantages: greater simplicity, reliability and enhanced power.
High compression. The Cyclone Engine is an external combustion/internal expansion engine, using variable timing, variable compression ratios and multiple heat exchangers to increases in engine efficiency. A reheat stage is included at lower compression ratios.
Cyclones can use almost any liquid or gaseous fuel. Power produced we be based on the energy content of the fuel in use. The design of the engine obviates the need for a separate cooling system.
The basic Cyclone engine is a compact, one-piece unit that can develop 3 hp per cubic inch of displacement, compared to a ballpark one horsepower per 1.5 cubic inches of displacement for a gasoline engine.
A Cyclone with three or more cylinders is self-starting—i.e., no flywheel needs to be turned by a starter. Pulling the throttle lever activates flow through individual needle valves situated at each cylinder. From a dead stop, the engine attains its highest torque within less than one crankshaft revolution and transitions to engine horsepower at 5,250 rpm giving the Cyclone a remarkably robust power band.
The Cyclone Engine exhausts into the condenser, where the vapor is totally contained, not into the atmosphere. As a result, it requires no exhaust system muffler or catalytic converter.
Vibration is controlled because the crankshaft is counter weighted and the pulsations are balanced by equal offsetting pressures, thus requiring no harmonic dampener.
The Cyclone Engine is smaller than four-stroke internal combustion engines, with fewer parts. However, the materials handling the high operating temperatures and pressures are more expensive. At similar economies of scale, the two types of engines should be comparable in cost.
Applications. Harry Schoell, the inventor of the Cyclone, forsees a large range of applications for his engine, from small electrical generators in the 1 kW range up through medium-size cyclones for light-duty vehicles, large Cyclones of up to 1,000 hp for the heavy-duty diesel market and beyond to larger ships and generators.
US Patent 7,080,512: Heat regenerative engine
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