Replacing the Internal Combustion Engine Dronfield U3A Modern Science Group considered various alternatives to the Internal Combustion Engine (ICE). The following 5 alternative engine architectures have one major feature in common with the standard piston engines that have dominated the automobile for more than a century: Fuel is burned inside a chamber to convert chemical energy into mechanical energy for propulsion. However, that requires moving air and fuel in and exhaust gases out of the combustion chamber, all of which adds complexity and reduces efficiency. Stirling In 1816, Scottish inventor Robert Stirling conceived of the closed-cycle engine with the working fluid (in this case, air) remaining contained within the device. The heat source—which could be almost anything, including combustion—is external to the engine. Pairs of pistons operate together to provide the complete cycle. The air in one chamber is heated via heat transfer through the cylinder wall pushing back the displacer piston, which is linked to a second power piston in the expansion chamber. As the heated air continues to expand, it displaces the power piston, which drives a crankshaft that produces rotational torque. As the air cools, both pistons move back to their original positions, and the process repeats. Until recently, Stirling engines were mainly used for stationary applications—in part because they were not suitable for typical transient applications where the power delivery varied significantly over time. However, newer configurations and the ability to use alternative fuels have revived interest, especially for range-extender applications where constant speed operation and low noise (due to the continuous external combustion) are beneficial. Opposed-Piston Opposed Cylinder (OPOC) The opposed-piston opposed-cylinder (OPOC) architecture has drawn considerable attention recently with the emergence of a new company called Ecomotors. Ecomotors includes numerous veteran auto-industry executives and engineers, including Don Runkle of General Motors and Peter Hofbauer, formerly of Volkswagen.
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Replacing the Internal Combustion Engine Dronfield U3A Modern Science Group considered various alternatives to the Internal Combustion Engine (ICE).
The following 5 alternative engine architectures have one major feature in common with the standard piston engines that have dominated the automobile for more than a century: Fuel is burned inside a chamber to convert chemical energy into mechanical energy for propulsion. However, that requires moving air and fuel in and exhaust gases out of the combustion chamber, all of which adds complexity and reduces efficiency.
Stirling In 1816, Scottish inventor Robert Stirling conceived of the closed-cycle engine with the working fluid (in this case, air) remaining contained within the device. The heat source—which could be almost anything, including combustion—is external to the engine. Pairs of pistons operate together to provide the complete cycle. The air in one chamber is heated via heat transfer through the cylinder wall pushing back the displacer piston, which is linked to a second power piston in the expansion chamber. As the heated air continues to expand, it displaces the power piston, which drives a crankshaft that produces rotational torque. As the air cools, both pistons move back to their original positions, and the process repeats. Until recently, Stirling engines were mainly used for stationary applications—in part because they were not suitable for typical transient applications where the power delivery varied significantly over time. However, newer configurations and the ability to use alternative fuels have revived interest, especially for range-extender applications where constant speed operation and low noise (due to the continuous external combustion) are beneficial.
Opposed-Piston Opposed Cylinder (OPOC)
The opposed-piston opposed-cylinder (OPOC) architecture has drawn considerable attention
recently with the emergence of a new company called Ecomotors. Ecomotors includes numerous
veteran auto-industry executives and engineers, including Don Runkle of General Motors and
Peter Hofbauer, formerly of Volkswagen.
The primary claimed advantage of the OPOC architecture is high power density and fuel
efficiency improvements of 50 percent over current spark-ignition engines. Ecomotors has
developed a modular configuration with each module consisting of two cylinders. Within each
cylinder are two pistons that are linked to a common crankshaft. The pairs of pistons oscillate
back and forth with a common combustion chamber between them. The OPOC engine operates
on a two-stroke cycle, with each piston exposing only the intake or exhaust ports, allowing better
management of which ports are open by timing each piston.
Hofbauer explains that the use of two pistons per cylinder allows the pistons to move only half
the distance for the same compression ratio so that the engine can run twice as fast. Like many
of these alternative architectures, the OPOC engine can run on a variety of fuels including both
gasoline and diesel as well as biofuels. Modules of two cylinders each can be joined together
providing as much power as needed for a given application while electronically controlled
clutches allow the individual modules to be shut down for reduced fuel consumption during light
loads.
Scuderi
For more than a century, virtually all the engines used have operated on either a two- or four-stroke Diesel or Otto cycle, with the entire combustion cycle taking place within any number of single cylinders. Each cylinder would have intake, compression, power and exhaust activities. The idea of the split cycle—in which one cylinder handles intake and compression and a second handles power and exhaust—dates back to at least the late 19th century, yet no one has ever had much success with it. The Scuderi Group hopes to change that with a split-cycle design it has been developing over the last several years. Each engine module consists of two cylinders and pistons tied together through the crankshaft and a high-pressure crossover passage. Because only air is being squeezed into the first cylinder, it has 75:1 compression ratio. The outlet valve of cylinder one releases the high-pressure air into a crossover passage where some cooling occurs. When the inlet to the second cylinder opens as that piston approaches the top of its stroke,
the high-pressure air rushes in from the crossover. After the valve closes, fuel is injected and ignited about 15 degrees past top dead center. This timing ensures that the air is not recompressed, which improves overall thermodynamic efficiency. Scuderi claims a normally aspirated version of its engine can produce up to 135 hp per liter, giving it much better power density and lower fuel consumption than conventional engines. An air-hybrid version using a high-pressure accumulator that is charged during vehicle coast-down could improve efficiency by another 50 percent. The Scuderi concept is compatible with spark-ignition operation on gasoline and other fuels or compression ignition with diesel fuel. The first functional Scuderi engine began testing on a dynamometer in mid-2009, and the company hopes to strike a production deal with an automaker within five years.
Free-Piston
The free-piston engine has some similarities to the OPOC but generally only uses two pistons per module. The pistons are attached to each end of a solid connecting rod and oscillate back and forth in the cylinder, alternately firing each piston on a two-stroke cycle. Free-piston engines have lower friction than traditional crankshaft-based piston engines as a result of reduced rotary motion. A free-piston engine can achieve up to 50 percent thermodynamic efficiency, or about double the efficiency of a conventional gasoline engine. However, that same lack of rotary motion makes this design problematic for use as a propulsion unit. One architectural configuration of the free-piston engine that could prove useful in the future is to use it as a generator for an extended range electric vehicle. Copper windings around
the central section of the cylinder could be combined with magnets on the connecting rod to generate electricity that would be used to charge a battery. The compact size of the engine and nearly vibration-free operation make this a viable alternative for these electrically driven cars.
Wankel
Felix Wankel's rotary design is not exactly a new engine architecture, having been used in a variety of production cars since he completed the first running prototype in 1957. Like several of the other architectures discussed here, the Wankel has the benefit of very high power density. The current 1.3-liter normally aspirated two-rotor design used by Mazda in the RX-8 sports car generates 238 hp. Unfortunately, Wankels have had issues with high fuel and oil consumption, which has limited their use in recent decades. However, several modern developments have made a revival of the Wankel a distinct possibility. New machining processes can provide much-improved surface finish on the chamber walls, and new seal materials can reduce oil consumption and improve durability. The addition of direct fuel injection will facilitate reduced fuel consumption and emissions by preventing unburned fuel from flowing out through the ports as the rotor sweeps by. The emergence of extended range electric vehicles (ER-EV), like the Chevrolet Volt, has suddenly provided a seemingly ideal application for Wankels. Because the engine in these vehicles is only used to drive a generator, it can be optimized for operation at certain fixed speeds rather than transient operation. The compact dimensions also make it easier to package in this type of vehicle, and its vibration-free operation allows more seamless charge-sustaining operation. At the 2010 Geneva Motor Show, Audi showed an ER-EV
concept based on its new sub-compact A1 that uses a Wankel range extender, and powertrain engineering consultants AVL and FEV have both shown similar demonstration vehicles in recent months. Even General Motors has acknowledged investigating the use of a Wankel for future generations of the Volt.
Using different Fuel
Hydrogen internal combustion engine vehicle
A hydrogen internal combustion engine vehicle (HICEV) is a type of hydrogen
vehicle using an internal combustion engine. Hydrogen internal combustion engine vehicles
are different from hydrogen fuel cell vehicles (which use hydrogen + oxygen rather than
hydrogen + air); the hydrogen internal combustion engine is simply a modified version of the
traditional gasoline-powered internal combustion engine.
History
Francois Isaac de Rivaz designed in 1806 the De Rivaz engine, the first internal combustion
engine, which ran on a hydrogen/oxygen mixture. Étienne Lenoir produced the
Hippomobile in 1863. Paul Dieges patented in 1970 a modification to internal combustion
engines which allowed a gasoline-powered engine to run on hydrogen.
Mazda has developed Wankel engines that burn hydrogen. The advantage of using ICE
(internal combustion engine) such as wankel and piston engines is that the cost of retooling
for production is much lower. Existing-technology ICE can still be used to solve those
problems where fuel cells are not a viable solution as yet, for example in cold-weather
applications.
BMW tested a supercar named the BMW Hydrogen 7, powered by a hydrogen ICE, which
achieved 301 km/h (187 mph) in tests At least two of these concepts have been
manufactured.
HICE forklift trucks have been demonstrated based on converted diesel internal combustion
engines with direct injection.
Alset GmbH developed a hybrid hydrogen systems that allows vehicle to use petrol and
hydrogen fuels individually or at the same time with an internal combustion engine. This
technology was used with Aston Martin Rapide S during the 24 Hours Nürburgring race. The
Rapide S was the first vehicle to finish the race with hydrogen technology.
Liquid nitrogen tanks can be disposed of or recycled with less pollution than
batteries.
current battery systems. Liquid nitrogen vehicles are unconstrained by the
degradation problems associated with
The tank may be able to be refilled more often and in less time than batteries can be
recharged, with re-fueling rates comparable to liquid fuels.
It can work as part of a combined cycle powertrain in conjunction with a petrol or
diesel engine, using the waste heat from one to run the other in
a turbocompound system. It can even run as a hybrid system.
Disadvantages
The principal disadvantage is the inefficient use of primary energy. Energy is used to liquefy nitrogen, which in turn provides the energy to run the motor. Any conversion of energy has losses. For liquid nitrogen cars, electrical energy is lost during the liquefaction process of nitrogen.
Liquid nitrogen is not available in public refueling stations; however, there are distribution
systems in place at most welding gas suppliers and liquid nitrogen is an abundant by-
product of liquid oxygen production.
A New Car Engine
Despite shifting into higher gear within the consumer's green conscience, hybrid vehicles are
still tethered to the gas pump via a fuel-thirsty 100-year-old invention: the internal
combustion engine.
However, researchers at Michigan State University have built a prototype gasoline engine
that requires no transmission, crankshaft, pistons, valves, fuel compression, cooling systems
or fluids. Their so-called Wave Disk Generator could greatly improve the efficiency of gas-
Electric bicycle wheels are coming to the masses, and they are coming from multiple
sources. A few years ago we saw the Copenhagen Wheel, and now a similar product
is making its way to market – the FlyKly Smart Wheel.
The Smart Wheel is designed to work on almost any bicycle. The 250W electric
motor automatically kicks in when the user starts pedaling, and it stops when the
user does. As is the case with conventional electric bikes, this allows riders to pedal
with less effort.
The motor allows for a top speed of 20 mph (32 km/h) with a 30-mile (48-km) range.
The whole wheel weighs in at 9 lb (4 kg), and will be available in 20, 26, and 29-inch
sizes.
Aside from the actual motor, the wheel also comes with a mobile application that
offers features like the ability to lock the motor, track it in the event that it is stolen,
and set the top speed while riding.
How an electric bike works
Allows the rider to add power to their pedalling with a small electric motor
Most have lithium batteries with a range of 20 to 25 miles (32 to 40km)
Power-assisted speed limit of 15mph (25km/h) in the UK, but - as with standard bikes - can exceed that when under pedal power alone
Some models have power-assisted pedalling
Others have a throttle and/or a handlebar-mounted control panel and let the motor take most of the strain
Electric bikes come in many shapes and sizes, with prices starting at about £500 and rising to £2,000 or more.
You have to be pedalling for the motor to run and, by law, it cuts out at 15 mph (25km/h). Getting the heavier models to go much faster is not easy, but in a city that's a perfectly reasonable speed - although it can mean the more traditional cyclists left at the lights quickly catch up on the flat.
There's no licence to worry about, no insurance, and instead of trips to the petrol pump, the battery - which lasts for about 20 miles - is charged from a power socket.
So why do electric bikes remain something of a novelty?
Among those who will not be buying one in a hurry is Cycling Plus editor Rob Spedding, a self-confessed middle-aged man in lycra. For enthusiasts like him, the point is pedalling hard and getting fit.
Inventor Clive Sinclair devised the C5 from 1985, and a powered bike in 1994
But Spedding says that to judge electric bikes on these terms alone is wrong.
"It's a really good entry point into cycling," he says.
As electric bikes still have to be pedalled, an element of exercise is unavoidable - even if hills are less daunting, says Spedding. And encouraging more people onto bikes of whatever kind reduces pollution and congestion on the roads.
"Seniors with e-bikes have been dealing with falling a lot, misjudging the speed and so on."
Courses are now being offered to help older riders cycle safely, including speed awareness and how to deal with junctions.It is the kind of enthusiasm seen in the Netherlands that London Mayor Boris Johnson has been trying to tap into.