Afterburning Ericsson Cycle Engine Low Cost Fuel Cell Alternative

Proe Power Systems

At first glance, there´s nothing new about "hot air" engines, of which Proe Power Systems´ Afterburning Ericsson Cycle (AEC) engine is one. But that´s where all similarities end. The AEC drop-kicks the hot air engine into the 21st Century.

Originally designed in the 1800s by engineering wiz John Ericsson -- better known for building the U.S. Civil War ironclad, USS Monitor -- Ericsson Cycle hot air engines (like the more famous but closely related Stirling Cycle hot air engines) produce power by externally heating one cylinder and cooling another, creating pressure that is used to produce power. In contrast, internal combustion engines produce power by burning gases in a cylinder to create pressure. A simple, reliable device, the Ericsson hot air engine was used primarily to pump water and power machinery.

Nothing much happened with the hot air engine for almost a hundred years. Several versions of Ericsson and Sterling engines have been developed with varying success but never achieved their promised performance because of an inherent inefficiency in the system -- before the AEC, hot air engines did not have the burner completely integrated with the engine. Although the engine efficiency could be improved by raising the temperature of the heated cylinder, as the heated engine cylinder grew hotter, it required more energy from the burner to raise the air temperature in it. That additional energy was wasted in the burner exhaust, reducing the overall engine-burner efficiency.

Enter Proe Power System´s AEC engine, with its unique, patented, integrated combustion/engine process. Key to its success is its newly developed, patent-pending recuperator -- a heat exchanger that recovers over 90% of the exhaust heat for higher thermodynamic efficiency and unmatched engine performance exceeding any conventional combustion engine or available fuel cell alternatives. This remarkable engine has virtually no burner efficiency loss because there´s no external burner. Instead, including the burner in the engine´s and recuperator´s regenerative heating process enables combustion to take place at the higher exhaust temperature and makes all the heat from that combustion available to the engine cycle.

Proe´s AEC engine provides complete, continuous combustion, obtaining nearly the full heating value of the fuel. And, unlike fuel cells, it can run on any available fuel, including gasoline, methane, and propane. Fuel cells require nearly pure hydrogen to operate and can use other fuels only if an expensive and inefficient reformer is used to extract the hydrogen from them. Even though fuel cells are highly efficient and require relatively small amounts of hydrogen, there is no national hydrogen network in place to deliver the fuel, requiring enormous expense to create the infrastructure necessary to supply the demand.

When using available fuels, the AEC and fuel cells have almost identical fuel consumption and emissions. But the AEC engine is far easier and less costly to build, requiring nothing more than a modestly equipped machine shop capable of rebuilding an automobile engine. In fact, the AEC´s recuperator has been built out of 316 steel using nothing more than a bandsaw, milling machine, and lathe. This simple construction enables even a small manufacturer to produce engines for tomorrow´s power market.

Because the new engine is so efficient in capturing the exhaust heat, it is ideal for combined heat and power (CHP) and distributed power generation applications. The AEC is well-suited for use as an auxiliary power source for the trucking industry to reduce noise and pollution from idling trucks, as a heat engine in hybrid vehicles, and as a clean replacement for marine diesel engines. The simple, easily manufactured engine does not require costly pollution controls or expensive tooling. Its clean combustion meets 21st century environmental requirements and promises long engine life, and any foreseeable competition is prevented by broad patent protection.