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45-459: In July 2014, Cyclone Power Technologies separated its waste heat engine product into the separate WHE Generation Corporation, which does business under the trade name Q2Power, Inc., of Lancaster, Ohio. 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

90-418: A conventional "counterflow" steam engine during the exhaust stroke. This condition allows higher thermal efficiency. The exhaust ports are open for only a small fraction of the piston stroke, with the exhaust ports closed just after the piston begins traveling toward the admission end of the cylinder. The steam remaining within the cylinder after the exhaust ports are closed is trapped, and this trapped steam

135-407: A two-stroke internal combustion engine, and it is possible to convert a two-stroke engine to a uniflow steam engine by feeding the cylinder with steam via a " bash valve " fitted in place of the spark plug. As the rising piston nears the top of its stroke, it knocks open the bash valve to admit a pulse of steam. The valve closes automatically as the piston descends, and the steam is exhausted through

180-548: 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. No independent tests of any WHE model have been reported, but an indication comes from information published regarding

225-402: A 34% cutoff. 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

270-581: A Uniflow engine was in Atkinson steam wagons , in 1918. Only one such steam wagon is known to be still in existence; it was built in 1918, spent its working life and a period of dereliction in Australia, and was then repatriated to England and restored by Tom Varley in 1976-77. The final commercial evolution of the uniflow engine occurred in the United States during the late 1930s and 1940s by

315-421: A complete waste heat recovery system. Uniflow steam engine The uniflow type of steam engine uses steam that flows in one direction only in each half of the cylinder. Thermal efficiency is increased by having a temperature gradient along the cylinder. Steam always enters at the hot ends of the cylinder and exhausts through ports at the cooler centre. By this means, the relative heating and cooling of

360-400: A large cylinder volume. To gain the maximum potential work from the engine a high reciprocation rate is required, typically 80% faster than a double-acting counterflow type engine. This causes the opening times of the inlet valves to be very short, putting great strain on a delicate mechanical part. In order to withstand the huge mechanical forces encountered, engines have to be heavily built and

405-416: A large flywheel is required both to smooth out the variations in torque as the steam pressure rapidly rises and falls in the cylinder and to compensate for the inertia of the heavy piston. Because there is a thermal gradient across the cylinder, the metal of the wall expands to different extents. This requires the cylinder bore to be machined wider in the cool center (sometimes described as "egg-shaped") than at

450-468: 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. 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

495-485: 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 by OSU-CAR described the engine bearings as a "critical path issue" and stated: The contract between Cyclone Power Technologies and Phoenix Power Group for the WHE states that Phoenix Power Group will make

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540-429: 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

585-401: 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

630-760: A year previously in 1908. The uniflow principle was mainly used for industrial power generation, but was also tried in a few railway locomotives in England, such as the North Eastern Railway uniflow locomotives No.825 of 1913, and No.2212 of 1918, and the Midland Railway Paget locomotive . Experiments were also made in France, Germany, the United States and Russia. In no case were the results encouraging enough for further development to be undertaken. The first large-scale utilization of

675-452: Is a quantity relating to the operation of a reciprocating engine and is a measure of an engine's capacity to do work that is independent of engine displacement . Despite having the dimension of pressure, MEP cannot be measured. When quoted as an indicated mean effective pressure ( IMEP ), it may be thought of as the average pressure acting on a piston during the different portions of its cycle . When friction losses are subtracted from

720-432: 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

765-409: Is calculated using the indicated power ; i.e., the pressure volume integral in the work per cycle equation. Sometimes the term FMEP (friction mean effective pressure) is used as an indicator of the mean effective pressure lost to friction (or friction torque) and is just the difference between IMEP and BMEP. A four-stroke engine produces 159 N·m of torque, and displaces 2000 cm If we know

810-480: Is compressed by the returning piston. This is thermodynamically desirable as it preheats the hot end of the cylinder before the admission of steam. However, the risk of excessive compression often results in small auxiliary exhaust ports being included at the cylinder heads. Such a design is called a semi-uniflow engine Engines of this type usually have multiple cylinders in an in-line arrangement, and may be single- or double-acting. A particular advantage of this type

855-408: 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

900-475: 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. 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

945-436: Is that the valves may be operated by the effect of multiple camshafts, and by changing the relative phase of these camshafts, the amount of steam admitted may be increased for high torque at low speed, and may be decreased at cruising speed for economy of operation. Alternatively, designs using a more-complex cam surface allowed the varying of timing by shifting the entire camshaft longitudinally compared to its follower, allowing

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990-538: 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

1035-431: The 3-cylinder WHE-DR that has been under development since. A display model of a 12-cylinder radial engine was built, but it is not known if any working engines were built in this configuration. 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

1080-548: The Great Lakes cement carrier SS  St. Marys Challenger , installed when the vessel was re-powered in 1950. In small sizes (less than about 1,000 hp (750 kW)), reciprocating steam engines are much more efficient than steam turbines. White Cliffs Solar Power Station used a three-cylinder uniflow engine with " Bash "-type admission valves to generate about 25 kW electrical output. The single-acting uniflow steam engine configuration closely resembles that of

1125-474: The IMEP, the result is the brake mean effective pressure ( BMEP ). Let: Then, BMEP may be used to determine an engine's power output as follows: Since we know that power is: We now see that, BMEP is a measure of expressing torque per displacement: And thus, the equation for BMEP in terms of torque is: Speed has dropped out of the equation, and the only variables are the torque and displacement volume. Since

1170-806: The Skinner Engine Company with the development of the Compound Unaflow Marine Steam Engine. This engine operates in a steeple compound configuration and provides efficiencies approaching contemporary diesels. Many car ferries on the Great Lakes were so equipped, one of which is still operating, SS  Badger of 1952. The Casablanca -class escort carrier , the most prolific aircraft carrier design in history, used two 5-cylinder Skinner Unaflow engines, but these were not steeple compounds. A non-compound Skinner Uniflow remained in service until 2013 in

1215-421: The WHE, also invented what he called a 'spider bearing', 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

1260-463: The admission timing to be varied. (The camshaft could be shifted by mechanical or hydraulic devices.) And, by changing the absolute phase, the engine's direction of rotation may be changed. The uniflow design also maintains a constant temperature gradient through the cylinder, avoiding passing hot and cold steam through the same end of the cylinder. In practice, the uniflow engine has a number of operational shortcomings. The large expansion ratio requires

1305-446: 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." Elimination of

1350-431: 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. Thus, water is about 250 times less effective of

1395-481: The crankshaft speed, we can also determine the engine's power output from the MEP figure: P = i ⋅ n ⋅ V d ⋅ p me {\displaystyle P=i\cdot n\cdot V_{\text{d}}\cdot p_{\text{me}}} In our example, the engine puts out 159 N·m of torque at 3600 min (=60 s ): Thus: As piston engines usually have their maximum torque at

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1440-422: The cylinder walls is reduced. Steam entry is usually controlled by poppet valves (which act similarly to those used in internal combustion engines ) that are operated by a camshaft . The inlet valves open to admit steam when minimum expansion volume has been reached at the start of the stroke. For a period of the crank cycle, steam is admitted, and the poppet inlet is then closed, allowing continued expansion of

1485-471: The existing cylinder porting. The inertia of the flywheel then carries the piston back to the top of its stroke against the compression, as it does in the original form of the engine. Also like the original, the conversion is not self-starting and must be turned over by an external power source to start. An example of such a conversion is the steam-powered moped, which is started by pedalling. Mean effective pressure The mean effective pressure ( MEP )

1530-425: 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

1575-429: The features of a uniflow engine can be seen, with a large piston almost half the length of the cylinder, poppet inlet valves at either end, a camshaft (whose motion is derived from that of the driveshaft) and a central ring of exhaust ports. Uniflow engines potentially allow greater expansion in a single cylinder without the relatively cool exhaust steam flowing across the hot end of the working cylinder and steam ports of

1620-445: 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". Regardless of

1665-463: The hot ends. If the cylinder is not heated correctly, or if water enters, the delicate balance can be upset causing seizure mid-stroke and, potentially, destruction. The uniflow engine was first used in Britain in 1827 by Jacob Perkins and was patented in 1885 by Leonard Jennett Todd . It was popularised by German engineer Johann Stumpf in 1909, with the first commercial stationary engine produced

1710-543: 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 . Registration includes the requirements that the boiler's design be approved as meeting

1755-448: The range of maximum brake mean effective pressures for good engine designs is well established, we now have a displacement-independent measure of the torque-producing capacity of an engine design – a specific torque of sorts. This is useful for comparing engines of different displacements. Mean effective pressure is also useful for initial design calculations; that is, given a torque, standard MEP values can be used to estimate

1800-410: The required engine displacement. However, mean effective pressure does not reflect the actual pressures inside an individual combustion chamber – although the two are certainly related – and serves only as a convenient measure of performance. Brake mean effective pressure (BMEP) is calculated from measured dynamometer torque. Net indicated mean effective pressure (IMEP)

1845-414: The spider bearing was the only design change that would have led to this improvement. 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

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1890-407: The steam during the stroke, driving the piston. Near the end of the stroke, the piston will uncover a ring of exhaust ports mounted radially around the centre of the cylinder. These ports are connected by a manifold and piping to the condenser, lowering the pressure in the chamber below that of the atmosphere causing rapid exhausting. Continued rotation of the crank moves the piston. From the animation,

1935-655: The test waste heat recovery system for Bent Glass Design of Hatboro, PA. 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. Efficiency = power out power in = 10 k W 146.5 k W = 6.8 % {\displaystyle {\text{Efficiency}}={{\text{power out}} \over {\text{power in}}}={10kW \over 146.5kW}=6.8\%} The WHE-25 engine has

1980-437: 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. 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

2025-428: 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. 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

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