Cyclone Waste Heat Engine

Last updated October 10, 2023

The Cyclone Waste Heat Engine (WHE) is a small steam engine developed to produce power from steam created from waste heat. It is an offshoot of the development of the Cyclone Mark V Engine by the company Cyclone Power Technologies of Pompano Beach, Florida. The original versions were designed by inventor Harry Schoell, founder of Cyclone Power Technologies and the later versions have been designed by the Ohio State University Center for Automotive Research (OSU-CAR).

Engine construction and operation

The Cyclone Waste Heat Engine (WHE) is a single-acting, Uniflow steam engine. The two main variations are the WHE-25, a six-cylinder radial engine that was under development until November 2013, and the 3-cylinder WHE-DR that has been under development since.^[2] A display model of a 12-cylinder radial engine was built,^[3] but it is not known if any working engines were built in this configuration.

Operation

The timing on the admission valve(s) is arranged so that no matter what position the engine is in when it stopped last, the valve to at least one cylinder will always be open. This allows the engine to start by itself whenever steam is supplied to it, without other means such as an electric starter motor to cause the engine to initially rotate.

The fraction of the stroke in which the admission valve is open on a steam engine is termed the cutoff. On the WHE-25 it is 34% of the stroke.^[4] From top dead center to 34% of stroke, the crank turns through an angle of about 71°. In the six cylinder engine, one piston reaches top dead center every 360°/6 = 60°. The three cylinder WHE-DR engine only has a piston reach TDC every 120°, so its admission valve must be open over a much larger angle to ensure the engine is self-starting. If the valve is open for 130° of crankshaft rotation, the cutoff value would be about 64%.

The expansion stroke of the steam engine covers piston travel from top dead center to bottom dead center. When the piston reverses to return to top dead center, an exhaust valve needs to open so that the expanded steam from the previous stroke can be released from the cylinder. The WHE engine has an exhaust valve in each piston actuated by a protrusion on the connecting rod (see figure to right). On the exhaust stroke the angle of the connecting rod causes it to open the piston valve, allowing expanded steam to exhaust into the crankcase.

The WHE-25 design used a reed valve, which is a piece of thin metal covering the top of the piston (as shown in the figure). The WHE-DR design replaced the reed with a ball resting in a valve seat in the piston crown.^[5]

'Spider bearing'

The WHE-25 is designed with six connecting rods sharing one crankpin on the crankshaft. The standard design for such connection is with a master connecting rod connected to one piston and the remaining rods connected to pins in the big end of the master rod. Harry Schoell, inventor of the WHE, also invented what he called a 'spider bearing',^[6] which is a disk that can rotate around the crankpin, and has one bearing journal around its periphery for each of the six connecting rods. While this design eliminates the need for a separate master rod, it introduces one uncontrolled degree of freedom, i.e., the spider bearing itself can rotate in one direction until its motion is stopped by impacting with the connecting rods, then rotate in the other direction through some angle before it is stopped by again impacting connecting rods.

The WHE-DR design eliminated the spider bearing by having each cylinder offset from the others longitudinally so that the connecting rod big ends can fit on a shared crankpin side by side. It has been reported that "Initial testing has demonstrated significantly smoother and quieter operation."^[2] Elimination of the spider bearing was the only design change that would have led to this improvement.

Water lubrication

The Waste Heat Engine's design requires the use of water to lubricate the moving parts because exhaust steam goes into the engine crankcase. Any oil used to lubricate crankshaft and connecting rod bearings would soon form an emulsion of oil and water that would have very poor lubricating properties.

Journal bearings on the crankshaft and connecting rods and the pistons sliding in their cylinders operate in the hydrodynamic lubrication regime. The carrying capacity of a journal bearing is a direct function of the dynamic viscosity of the lubricating fluid. Water at 20 °C has a viscosity of 0.001002 Pa·s, while a typical motor oil could have a viscosity of about 0.250 Pa·s.^[7] Thus, water is about 250 times less effective of a lubricant than oil.

Cyclone Power Technologies had contracted with the Ohio State University Center for Automotive Research (OSU-CAR) for engineering analysis. A March 8, 2014 presentation^[5] by OSU-CAR described the engine bearings as a "critical path issue" and stated:

"Little or no data exists outside Cyclone’s own experience for the use of water lubrication for either ball bearings or roller bearings in our environment and under our loadings. Calculated life using just the bearing load and the scaling factors for the viscosity of the lubricant indicate that very high ratio of load capacity to applied load is required."
"Minimal data exists for the use of water lubricated polymer journal bearings in our environment and under our loadings. Factors of a 4:1 increase in life have been shown with submerged operation, but little long term wear data is available with pressurized water lubrication."

The contract between Cyclone Power Technologies and Phoenix Power Group for the WHE^[8] states that Phoenix Power Group will make a $150,000 progress payment "Upon the completion of 200 hours of durability testing of WHE version 5.0 as conducted and/or overseen by OSU. The durability testing shall consist of the WHE engine operating, without failure, and producing 10hp to 20hp". As of March 25, 2015 there has been no indication they have made a water lubricated engine pass this 200-hour endurance test.

Efficiency

No independent tests of any WHE model have been reported, but an indication comes from information published regarding the test waste heat recovery system for Bent Glass Design of Hatboro, PA.^[9] The system was described as providing up to 10 kW electrical output using a WHE-25 model engine and "will convert over 500,000 BTUs of exhaust heat from the customer's glass manufacturing furnaces into electric power." A heat flow rate 500,000 BTU/hr equals 146.5 kW.

${\text{Efficiency}}={{\text{power out}} \over {\text{power in}}}={10kW \over 146.5kW}=6.8\%$

The WHE-25 engine has a 34% cutoff.^[4] This allows for the remaining 66% of the piston stroke to expand the steam, extracting work from it and causing the pressure to drop. The figure to the right shows how pressure in the cylinder of a steam engine drops after the cutoff point. The WHE-DR must have a much later cutoff to allow it to self-start. The later cutoff leads to a larger mean effective pressure that will give a larger power output for an engine of a given size operating at a given speed, but also leads to a decrease in efficiency since steam is at a higher pressure when exhausted from the cylinder and less of its energy has been converted to mechanical work.

Auxiliary equipment

Expander: A steam engine is just one component in a Rankine cycle power system. The figure of the Rankine cycle at the right shows a turbine rather than a reciprocating piston engine between states 3 and 4, but either device acts as the expander stage in the cycle.

Condenser: The device between states 4 and 1 is the condenser. It removes heat from the engine exhaust steam to condense it back into water. In the case of the WHE-25 engine in the previous sub-section, of the 146.5 kW of heat energy supplied in the initial steam, 10 kW was converted into electricity. That leaves 146.5 - 10 = 136.5 kW of heat energy to be removed by the condenser. As a point of comparison, a Caterpillar C13 diesel engine that is commonly used in tractor-trailer trucks has a heat rejection to coolant rating of 128 kW.^[10] Thus, a condenser for the WHE-25 engine producing 10 kW of power would be about the size of the radiator on a semi-truck. The newer WHE-DR is likely less efficient, so would need an even bigger condenser for the same output power.

The condenser requires enough airflow to take away the heat. A fan is usually used to create this airflow, and its power consumption reduces the net power available from the system.

Feed water pump: The condensed water is stored in a tank, then pumped to high pressure by the feed water pump, states 1 to 2 in the figure. This pump requires a source of power, as well as a control system so that it pumps the proper amount of water to compensate for the amount of steam put into the engine.

Boiler: Heat is added to the water in the boiler to create the steam, states 2 to 3 in the figure. Boilers are sometimes called steam generators, and Cyclone Power Technologies has used the term "Combustion Chamber/Heat Exchanger" or "CCHX".^[11] Regardless of the name used, if the system pressure is greater than 15 psi (1 bar) and heat is added, the device is legally a boiler. All states in the United States except Idaho and Wyoming and all provinces in Canada have legally adopted the requirement for boilers to be registered with the National Board of Boiler and Pressure Vessel Inspectors.^[12] Registration includes the requirements that the boiler's design be approved as meeting the ASME Boiler and Pressure Vessel Code (BPVC), must be constructed in a facility currently authorized by ASME to construct such boilers, must be installed and tested to the approval of a National Board inspector, and, is required to undergo periodic inspections at the owner's expense.

The jurisdiction may also require the installation be operated by a licensed stationary engineer, as well as be covered by sufficient liability insurance.

The reason for such scrutiny is because of the catastrophic losses that can occur due to a boiler explosion.

A system will also require an approved steam safety valve and water level control as well as valves for water into the boiler and steam to the engine. If the system is intended to run without supervision, then sensors and automatic safety shutdown systems are needed.

Thus, the waste heat engine may be one of the least expensive components of a complete waste heat recovery system.

Related Research Articles

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.

A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common features of all types. The main types are: the internal combustion engine, used extensively in motor vehicles; the steam engine, the mainstay of the Industrial Revolution; and the Stirling engine for niche applications. Internal combustion engines are further classified in two ways: either a spark-ignition (SI) engine, where the spark plug initiates the combustion; or a compression-ignition (CI) engine, where the air within the cylinder is compressed, thus heating it, so that the heated air ignites fuel that is injected then or earlier.

<span class="mw-page-title-main">Steam engine</span> Heat engine that performs mechanical work using steam as its working fluid

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is generally applied only to reciprocating engines as just described, not to the steam turbine. Steam engines are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.

The Watt steam engine design became synonymous with steam engines, and it was many years before significantly new designs began to replace the basic Watt design.

<span class="mw-page-title-main">Four-stroke engine</span> Internal combustion engine type

A four-strokeengine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed:

Intake: Also known as induction or suction. This stroke of the piston begins at top dead center (T.D.C.) and ends at bottom dead center (B.D.C.). In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing a partial vacuum in the cylinder through its downward motion.
Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke (below). Both the intake and exhaust valves are closed during this stage.
Combustion: Also known as power or ignition. This is the start of the second revolution of the four stroke cycle. At this point the crankshaft has completed a full 360 degree revolution. While the piston is at T.D.C. the compressed air-fuel mixture is ignited by a spark plug or by heat generated by high compression, forcefully returning the piston to B.D.C. This stroke produces mechanical work from the engine to turn the crankshaft.
Exhaust: Also known as outlet. During the exhaust stroke, the piston, once again, returns from B.D.C. to T.D.C. while the exhaust valve is open. This action expels the spent air-fuel mixture through the exhaust port.

The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in the cycle. It can also serve as a reversing gear. It is sometimes referred to as the "motion".

A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft. The connecting rod is required to transmit the compressive and tensile forces from the piston. In its most common form, in an internal combustion engine, it allows pivoting on the piston end and rotation on the shaft end.

<span class="mw-page-title-main">Compound steam engine</span> Steam engine where steam is expanded in stages

A compound steam engine unit is a type of steam engine where steam is expanded in two or more stages. A typical arrangement for a compound engine is that the steam is first expanded in a high-pressure (HP) cylinder, then having given up heat and losing pressure, it exhausts directly into one or more larger-volume low-pressure (LP) cylinders. Multiple-expansion engines employ additional cylinders, of progressively lower pressure, to extract further energy from the steam.

In a piston engine, the crankcase is the housing that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block.

hot-bulb engine Internal combustion engine

The hot-bulb engine is a type of internal combustion engine in which fuel ignites by coming in contact with a red-hot metal surface inside a bulb, followed by the introduction of air (oxygen) compressed into the hot-bulb chamber by the rising piston. There is some ignition when the fuel is introduced, but it quickly uses up the available oxygen in the bulb. Vigorous ignition takes place only when sufficient oxygen is supplied to the hot-bulb chamber on the compression stroke of the engine.

A Cornish engine is a type of steam engine developed in Cornwall, England, mainly for pumping water from a mine. It is a form of beam engine that uses steam at a higher pressure than the earlier engines designed by James Watt. The engines were also used for powering man engines to assist the underground miners' journeys to and from their working levels, for winching materials into and out of the mine, and for powering on-site ore stamping machinery.

A hit-and-miss engine or Hit 'N' Miss is a type of stationary internal combustion engine that is controlled by a governor to only fire at a set speed. They are usually 4-stroke but 2-stroke versions were made. It was conceived in the late 19th century and produced by various companies from the 1890s through approximately the 1940s. The name comes from the speed control on these engines: they fire ("hit") only when operating at or below a set speed, and cycle without firing ("miss") when they exceed their set speed. This is as compared to the "throttle governed" method of speed control. The sound made when the engine is running without a load is a distinctive "Snort POP whoosh whoosh whoosh whoosh snort POP" as the engine fires and then coasts until the speed decreases and it fires again to maintain its average speed. The snorting is caused by the atmospheric intake valve used on many of these engines.

The term six-stroke engine has been applied to a number of alternative internal combustion engine designs that attempt to improve on traditional two-stroke and four-stroke engines. Claimed advantages may include increased fuel efficiency, reduced mechanical complexity, and/or reduced emissions. These engines can be divided into two groups based on the number of pistons that contribute to the six strokes.

Internal combustion engines come in a wide variety of types, but have certain family resemblances, and thus share many common types of components.

High-speed steam engines were one of the final developments of the stationary steam engine. They ran at a high speed, of several hundred rpm, which was needed by tasks such as electricity generation.

The Cyclone Mark V Engine is a steam engine in which the engine, steam generator, condenser and feed pump are integrated into a single compact unit. The company Cyclone Power Technologies of Pompano Beach, Florida was founded by inventor Harry Schoell to develop and market this engine. The Cyclone Mark V Engine is a six cylinder radial uniflow engine of two inch bore and two inch stroke. Pistons are single acting. The engine is claimed to produce 100 hp at 3,600 rpm using steam at 3,200 psi and 1,200 °F.

An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.

The Willans engine or central valve engine was a high-speed stationary steam engine used mainly for electricity generation around the start of the 20th century.

The 4 VD 14,5/12-1 SRW is an inline four-cylinder diesel engine produced by the VEB IFA Motorenwerke Nordhausen from 1967 to 1990. The engine was one of the standard modular engines for agricultural and industrial use in the Comecon-countries. Approximately one million units were made.

The Mercedes-Benz OM 138 is a diesel engine manufactured by Daimler-Benz. In total, 5,719 units were produced between 1935 and 1940. It was the first diesel engine especially developed and made for a passenger car. The first vehicle powered by the OM 138 was the Mercedes-Benz W 138. The light Mercedes-Benz trucks L 1100 and L 1500 as well as the bus O 1500 were also offered with the OM 138 as an alternative to the standard Otto engine.

References

↑ Cyclone Power Technologies, Inc. Quarterly Report (Report). Securities and Exchange Commission. June 30, 2014.
1 2 "Cyclone Power Technologies completes build of next generation waste heat engine with The Ohio State University's Center for Automotive Research" (Press release). November 5, 2013.
↑ Curtis Ellzey interviews Harry Schoell about the Cyclone Waste Heat Engine – via youtube.com.
1 2 Cyclone Waste Heat Engine Specification Sheet. Retrieved from "Cyclone Waste Heat Engine Specifications" (PDF). cyclonepower.com. Archived from the original (PDF) on 2015-09-23. Retrieved 2015-03-22.
1 2 "ENGINEERING ANALYSIS OF CYCLONE POWER TECHNOLOGIES' WASTE HEAT ENGINE" (PDF). Archived from the original (PDF) on 2015-09-23. Retrieved 2015-03-21.
↑ USPatent 7900454,"Connecting rod journals and crankshaft spider bearing in an engine"
↑ Serway, Raymond A. (1996). Physics for Scientists & Engineers (4th ed.). Saunders College Publishing. ISBN 0-03-005932-1.
↑ Amended and Restated Systems Application License Agreement for Cyclone Power Technologies, Inc (Report). Securities and Exchange Commission. September 30, 2013.
↑ "Bent Glass Design Purchases Engine System From Cyclone Power Technologies" (Press release).
↑ "Caterpillar C13 diesel engine generator set specification sheet" (PDF). Archived from the original (PDF) on 2015-04-17. Retrieved 2015-03-25.
↑ "Cyclone Power Technologies and Phoenix Power Group Successfully Integrate Waste Oil Co-Generation System" (Press release).
↑ "National Board Synopsis Map 2015" (PDF). Archived from the original (PDF) on 2015-04-17. Retrieved 2015-03-25.

External links

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[2014q2-1] Cyclone Power Technologies, Inc. Quarterly Report (Report). Securities and Exchange Commission. June 30, 2014.

[whedr-2] 1 2 "Cyclone Power Technologies completes build of next generation waste heat engine with The Ohio State University's Center for Automotive Research" (Press release). November 5, 2013.

[vid20080602-3] Curtis Ellzey interviews Harry Schoell about the Cyclone Waste Heat Engine – via youtube.com.

[whe25specs-4] 1 2 Cyclone Waste Heat Engine Specification Sheet. Retrieved from "Cyclone Waste Heat Engine Specifications" (PDF). cyclonepower.com. Archived from the original (PDF) on 2015-09-23. Retrieved 2015-03-22.

[osupres-5] 1 2 "ENGINEERING ANALYSIS OF CYCLONE POWER TECHNOLOGIES' WASTE HEAT ENGINE" (PDF). Archived from the original (PDF) on 2015-09-23. Retrieved 2015-03-21.

[spider-6] USPatent 7900454,"Connecting rod journals and crankshaft spider bearing in an engine"

[7] Serway, Raymond A. (1996). Physics for Scientists & Engineers (4th ed.). Saunders College Publishing. ISBN 0-03-005932-1.

[PhoenixLic-8] Amended and Restated Systems Application License Agreement for Cyclone Power Technologies, Inc (Report). Securities and Exchange Commission. September 30, 2013.

[pr20090128-9] "Bent Glass Design Purchases Engine System From Cyclone Power Technologies" (Press release).

[10] "Caterpillar C13 diesel engine generator set specification sheet" (PDF). Archived from the original (PDF) on 2015-04-17. Retrieved 2015-03-25.

[pr20120927-11] "Cyclone Power Technologies and Phoenix Power Group Successfully Integrate Waste Oil Co-Generation System" (Press release).

[12] "National Board Synopsis Map 2015" (PDF). Archived from the original (PDF) on 2015-04-17. Retrieved 2015-03-25.

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