Digital Twin Spark Ignition

Definition

It is very interesting to know about complete combustion in automobile engineering. Because in actual practice, perfect combustion is not at all possible due to various losses in the combustion chamber as well as design of the internal combustion engine. Moreover the process of burning of the fuel is also not instantaneous. However an alternate solution to it is by making the combustion of fuel as fast as possible. This can be done by using two spark
plugs which spark alternatively at a certain time interval so as increase the diameter of the flame & burn the fuel instantaneously. This system is called DTSI (Digital Spark Ignition system). In this system, due to twin sparks, combustion will be complete. This paper represents the working of digital twin spark ignition system, how twin sparks are produced at 20,000 Volts, their timings, efficiency, advantages & disadvantages, diameter of the flame, how complete combustion is possible & how to decrease smoke & exhausts from the exhaust pipe of the bike using Twin Spark System.

DIGITAL TWIN SPARK ignition engine has two Spark plugs located at opposite ends of the combustion chamber and hence fast and efficient combustion is obtained. The benefits of this efficient combustion process can be felt in terms of better fuel efficiency and lower emissions. The, ignition system on the Twin spark is a digital system with static spark advance and no moving parts subject to wear. It is mapped by the integrated digital electronic control box which also handles fuel injection and valve timing. It features two plugs per cylinder.

This innovative solution, also entailing a special configuration of the hemispherical combustion chambers and piston heads, ensures a fast, wide flame front when the air-fuel mixture is ignited, and therefore less ignition advance, enabling, moreover, relatively lean mixtures to be used. This technology provides a combination of the light weight and twice the power offered by two-stroke engines with a significant power boost, i.e. a considerable"power-to-weight ratio" compared to quite a few four-stroke engines. Fig.1. show the actual picture of Bajaj Pulsar Bike.

Moreover, such a system can adjust idling speed & even cuts off fuel feed when the accelerator pedal is released, and meters the enrichment of the air-fuel mixture for cold starting and accelerating purposes; if necessary, it also prevents the upper rev limit from being exceeded. At low revs, the over boost is mostly used when overtaking, and this is why it cuts out automatically. At higher revving speeds the over boost will enhance full power delivery and will stay on as long as the driver exercises maximum pressure on the accelerator.

Main Characteristics

 Digital electronic ignition with two plugs per cylinder and two ignition distributors;
 Twin overhead cams with camshaft timing variation.
 Injection fuel feed with integrated electronic twin spark ignition.
 a high specific power
 compact design
 superior balance

This power unit, equipping the naturally aspirated 2-litre used on the Alfa 164, is a direc Ldeflvative of the engine fitted on the 2.0 Twin Spark version of the Alfa 75, a recent addition to the Alfa car range. It includes a number of exclusive engineering solutions resulting in superior power output and exceptional peak torque for this cylinder capacity. Its main characteristics are:

 Digital electronic ignition with two plugs per cylinder and two ignition distributors;
 Twin overhead cams with camshaft timing variation;
 Injection fuel feed with integrated electronic twin spark ignition.

Biodeisel

Definition

Bio-diesel is a vegetable oil processed to resemble Diesel Fuel. The first use of peanut oil was made in 1895 by Dr. Rudolf Diesel himself (1858-1913), who predicted- "The use of vegetable oils engine fuels may seem insignificant today. But such oils may become in course of time as important as petroleum and the coal tar products of the present time." Bio-diesel is the ethyl or methyl ester of fatty acid. Bio-diesel is made from virgin or used vegetable oils (both edible and non-edible) and animal fats through trans-esterification. Just like diesel, bio-diesel operates in compression ignition engines, which essentially require very little or no engine modifications up to require very little or no engine modifications up to 20% blends, and minor modifications for higher percentage blends because bio-diesel is similar to diesel but is very eco-friendly.

The Recent depletion and fluctuation in prices due to uncertain supplies for fossil fuel, make us to search renewable, safe and non-polluting sources of energy. India is not self sufficient in petroleum and has to import about two third of its requirements. Presently Indian Government spend Rupees 90,000 crores for petroleum fuel and annual consumption is around 40 millions tons. One of the solutions to the current oil crisis and toward off any future energy and economic crunch is to explore the feasibility of substitution of diesel with an alternative fuel which can be produced in our country on a massive scale to commercial utilization.

Indian Government, research institution and automobile industries are taking interest on bio-diesel from various non-edible oil bearing trees like Jatropha, Karanji, Mahua & Neem. As India is short of edible oils even for human consumption and since the cost of edible oil is also very high, it is preferable to use non-edible oils. Jatropha curcas is one of the prospective bio-diesel yielding crops. This paper highlights our work on alternate fuels and the importance of choosing jatropha. It reduces pollution drastically in terms of sulphates and carbon mono-oxide. To start with, we reduced the viscosity problem faced to a large extent by carrying out the transesterification process in our chemistry laboratory. we also studied the cost factor involved in the usage of jatropha. Performance test was conducted on an electrical loaded diesel engine and a study on the emissions was made using Exhaust Gas Analyser in our thermal laboratory. The pollution levels came down drastically and performance was better with various blends of jatropha and diesel.

Process Explanation

If methanol is used in the above reaction, it is termed methanolysis and fatty acid methyl esters are generated, which are called biodiesel. Three consecutive and reversible reactions are believed to occur in the transesterification which are given below:

Triglyceride + ROH Catalyst Diglyceride + R' COOR

Diglyceride + ROH Catalyst Monoglyceride + R" COOR

Monoglyceride +ROH Catalyst Glycerol + R"' COOR

The first step is the conversion of triglycerides to diglycerides, followed by the conversion of diglycerides to monoglycerides, and finally monoglycerides to glycerol, yielding one methyl ester molecule from each glyceride at each step. When methanol is used in the esterification A catalyst and excess alcohol are used to increase rate of reaction and to shift the equilibrium to the product side, respectively .

Performance Test On IC Engine

The engine used for the present investigation is a single cylinder "comet" vertical Diesel Engine (1500rpm, 3.5kW, water cooled). Engine is coupled with an eddy current dynamometer. In the present work, the experiments were carried out at constant speed and for varying load conditions i.e., no load, 25%, 50%, 75% and 100% of the rated load. The injection parameters were kept constant for the existing engine for entire test program. The static fuel injection timing and the fuel injection pressure for the given engine the 27 o before TDC and 220 bars respectively as specified by the manufacturer. The engine was started and warm-up with diesel fuel and then the diesel fuel line was cut off and simultaneously the fuel line, which connects the fuel under investigation, was opened. No additives were added to the system before conducting the test. Esterified vegetable oil was injected directly to the combustion chamber as conventional fuel injection. The test was done separately for the four fuels, which are taken for the investigation. In each case the observations were recorded after steady state was reached.

Thermo Acoustic Refrigeration

Definition

Thermo acoustic have been known for over years but the use of this phenomenon to develop engines and pumps is fairly recent. Thermo acoustic refrigeration is one such phenomenon that uses high intensity sound waves in a pressurized gas tube to pump heat from one place to other to produce refrigeration effect. In this type of refrigeration all sorts of conventional refrigerants are eliminated and sound waves take their place. All we need is a loud speaker and an acoustically insulated tube. Also this system completely eliminates the need for lubricants and results in 40% less energy consumption. Thermo acoustic heat engines have the advantage of operating with inert gases and with little or no moving parts, making them highly efficient ideal candidate for environmentally-safe refrigeration with almost zero maintenance cost. Now we will look into a thermo acoustic refrigerator, its principle and functions .

Basic Functioning

In a nut shell, a thermo acoustic engine converts heat from a high-temperature source into acoustic power while rejecting waste heat to a low temperature sink. A thermo acoustic refrigerator does the opposite, using acoustic power to pump heat from a cool source to a hot sink. These devices perform best when they employ noble gases as their thermodynamic working fluids. Unlike the chemicals used in refrigeration over the years, such gases are both nontoxic and environmentally benign. Another appealing feature of thermo acoustics is that one can easily flange an engine onto a refrigerator, creating a heat powered cooler with no moving parts at all.

The principle can be imagined as a loud speaker creating high amplitude sound waves that can compress refrigerant allowing heat absorption. The researches have exploited the fact that sound waves travel by compressing and expanding the gas they are generated in.

Suppose that the above said wave is traveling through a tube. Now, a temperature gradient can be generated by putting a stack of plates in the right place in the tube, in which sound waves are bouncing around. Some plates in the stack will get hotter while the others get colder. All it takes to make a refrigerator out of this is to attach heat exchangers to the end of these stacks.

It is interesting to note that humans feel pain when they hear sound above 120 decibels, while in this system sound may reach amplitudes of 173 decibels. But even if the fridge is to crack open, the sound will not be escaping to outside environment, since this intense noise can only be generated inside the pressurized gas locked inside the cooling system. It is worth noting that, prototypes of the technology has been built and one has even flown inside a space shuttle.

Thermo acoustic refrigerators now under development use sound waves strong enough to make your hair catch fire, says inventor Steven L Garrett. But this noise is safely contained in a pressurized tube. If the tube gets shattered, the noise would instantly dissipate to harmless levels. Because it conducts heat, such intense acoustic power is a clean, dependable replacement for cooling systems that use ozone destroying chlorofluorocarbons (CFCs). Now a scientist Hofler is also developing super cold cryocoolers capable of temperatures as low as -135°F (180°K). he hopes to achieve -243°F (120°K) because such cryogenic temperatures would keep electronic components cool in space or speed the function of new microprocessorsa

Solar Cars

Definition

The first solar car invented was a tiny 15-inch vehicle created by William G. Cobb of General Motors. Called the Sun mobile, Cobb showcased the first solar car at the Chicago Powerama convention on August 31, 1955. The solar car was made up 12 selenium photovoltaic cells and a small Pooley electric motor turning a pulley which in turn rotated the rear wheel shaft. The first solar car in history was obviously too small to drive . Now let's jump to 1962 when the first solar car that a person could drive was demonstrated to the public. The International Rectifier Company converted a vintage model 1912 Baker electric car (pictured above) to run on photovoltaic energy in 1958, but they didn't show it until 4 years later. Around 10,640 individual solar cells were mounted to the rooftop of the Baker to help propel it.

In 1977, Alabama University professor Ed Passereni built the Bluebird solar car, which was a prototype full scale vehicle. The Bluebird was supposed to move from power created by the photovoltaic cells only without the use of a battery. The Bluebird was exhibited in the Knoxville, TN 1982 World's Fair.Between 1977 and 1980 (the exact dates are not known for sure), at Tokyo Denki University, professor Masaharu Fujita first created a solar bicycle, then a 4-wheel solar car. The car was actually two solar bicycles put together. In 1979 Englishman Alain Freeman invented a solar car (pictured right). He road registered the same vehicle in 1980. The Freeman solar car was a 3-wheeler with a solar panel on the roof.

Energy Flow For A Solar Car

The energy from the sun strikes the earth throughout the entire day . However, the amount of energy changes due to the time of day, weather conditions, and geographic location. The amount of available solar energy is known as the solar isolation and is most commonly measured in watts per meter squared or W / m 2. In India on a bright sunny day in the early afternoon the solar isolation will be roughly around 1000 W / m 2, but in the mornings, evenings, or when the skies are overcast, the solar isolation will fall towards 0 W / m 2. It must understand how the available isolation changes in order to capture as much of the available energy as possible.

The sunlight hits the cells of the solar array, which produces an electrical current. The energy (current) can travel to the batteries for storage; go directly to the motor controller, or a combination of both. The energy sent to the controller is used to power the motor that turns the wheel and makes the car moves.

Generally if the car is in motion, the converted sun light is delivered directly to the motor controller, but there are times when there is more energy coming from the may than the motor controller needs. When this happens, the extra energy gets stored in the batteries for later use.

When the solar may can't produce enough energy to drive the motor at the desired speed, the array's energy is supplemented with stored energy from the batteries.

Of course, when the car is not in motion, all the energy from the solar may is stored in the batteries. There is also a way to get back some of the energy used to propel the car. When the car is being slowed down, instead of using the normal mechanical brakes, the motor is turned into a generator and energy flows backwards through the motor controller and into the batteries for storage. This is known as regenerative braking. The amount of energy returned to the batteries is small, but every bit helps.

Application

•  This concept can be utilized to build a single sitter four wheel vehicles in practice.

•  It can be extended to more commercial form of four wheeler vehicle.

•  In industry where small vehicles are used to perform light weight conveys work from one place to other place.

It can be used places where, fuel based vehicles are banned due to production of pollution and noise

Six Stroke Engine

Definition

Six Stroke engine, the name itself indicates a cycle of six strokes out of which two are useful power strokes. According to its mechanical design, the six-stroke engine with external and internal combustion and double flow is similar to the actual internal reciprocating combustion engine. However, it differentiates itself entirely, due to its thermodynamic cycle and a modified cylinder head with two supplementary chambers: combustion and an air heating chamber, both independent from the cylinder. In this the cylinder and the combustion chamber are separated which gives more freedom for design analysis. Several advantages result from this, one very important being the increase in thermal efficiency.

It consists of two cycles of operations namely external combustion cycle and internal combustion cycle, each cycle having four events. In addition to the two valves in the four stroke engine two more valves are incorporated which are operated by a piston arrangement.

The Six Stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake stroke and the compression stroke. The main advantages of six stroke engine includes reduction in fuel consumption by 40%, two power strokes in the six stroke cycle, dramatic reduction in pollution, adaptability to multi fuel operation. Six stroke engine's adoption by the automobile industry would have a tremendous impact on the environment and world economy.

Analysis Of Six Stroke Engine

Six-stroke engine is mainly due to the radical hybridization of two- and four-stroke technology. The six-stroke engine is supplemented with two chambers, which allow parallel function and results a full eight-event cycle: two four-event-each cycles, an external combustion cycle and an internal combustion cycle. In the internal combustion there is direct contact between air and the working fluid, whereas there is no direct contact between air and the working fluid in the external combustion process. Those events that affect the motion of the crankshaft are called dynamic events and those, which do not effect are called static events.

SIX-STROKE ENGINE CYCLE DIAGRAM

Multi Air Engine

Definition

The operating principle of the system, applied to intake valves, is the following: a piston, moved by a mechanical intake camshaft, is connected to the intake valve through a hydraulic chamber, which is controlled by a normally open on/off solenoid valve. When the solenoid valve is closed, the oil in the hydraulic chamber behaves like a solid body and transmits to the intake valves the lift schedule imposed by the mechanical intake camshaft. When the solenoid valve is open, the hydraulic chamber and the intake valves are de-coupled; the intake valves do not follow the intake camshaft anymore and close under the valve spring action.

The final part of the valve closing stroke is controlled by a dedicated hydraulic brake, to ensure a soft and regular landing phase in any engine operating conditions. Through solenoid valve opening and closing time control, a wide range of optimum intake valve opening schedules can be easily obtained. For maximum power, the solenoid valve is always closed and full valve opening is achieved following completely the mechanical camshaft, which is specifically designed to maximise power at high engine speed (long opening time).

For low-rpm torque, the solenoid valve is opened near the end of the camshaft profile, leading to early intake valve closing. This eliminates unwanted backflow into the manifold and maximises the air mass trapped in the cylinders. In engine part-load, the solenoid valve is opened earlier, causing partial valve openings to control the trapped air mass as a function of the required torque. Alternatively the intake valves can be partially opened by closing the solenoid valve once the mechanical camshaft action has already started. In this case the air stream into the cylinder is faster and results in higher in-cylinder turbulence. The last two actuation modes can be combined in the same intake stroke, generating a so-called Multilift mode that enhances turbulence and combustion rate at very low loads.

MultiJet for multiple injections, small diesel engines, and the recent Modular Injection technology, soon to be

Similarly, MultiAir technology will pave the way to further technological evolutions for petrol engines:

Integration of the MultiAir Direct air mass control with direct petrol Injection to further improve transient response and fuel economy. Introduction of more advanced multiple valve opening strategies to further reduce emissions. Innovative engine-turbocharger matching to control trapped air mass through a combination of optimum boost pressure and valve opening strategies.

While electronic petrol injection developed in the '70s and Common Rail developed in the '90s were fuel-specific breakthrough technologies, MultiAir Electronic Valve Control technology can be applied to all internal combustion engines whatever fuel they burn.

MultiAir, initially developed for spark ignition engines burning light fuel ranging from petrol to natural gas and hydrogen, also has wide potential for diesel engine emissions reduction

Pistonless Pump

Definition

Rocket engines requires a tremendous amount of fuel high at high pressure .Often th pump costs more than the thrust chamber.One way to supply fuel is to use the expensive turbopump mentioned above,another way is to pressurize fuel tank. Pressurizing a large fuel tank requires a heavy , expensive tank. However suppose instead of pressurizing entire tank, the main tank is drained into a small pump chamber which is then pressurized. To achieve steady flow, the pump system consists of two pump chambers such that each one supplies fuel for ½ of each cycle. The pump is powered by pressurized gas which acts directly on fluid. For each half of the pump system, a chamber is filled from the main tank under low pressure and at a high flow rate, then the chamber is pressurized, and then the fluid is delivered to the engine at a moderate flow rate under high pressure. The chamber is then vented and cycle repeats.

The system is designed so that the inlet flow rate is higher than the outlet flow rate.This allows time for one chamber to be vented , refilled and pressurized while the other is being emptied.A bread board pump has been tested and it works great .A high version has been designed and built and is pumping at 20 gpm and 550psi.

Nearly all of the hardware in this pump consists of pressure vessels, so the weight is low.There are less than 10 moving parts , and no lubrication issues which might cause problems with other pumps. The design and constr. Of this pump is st, forward and no precision parts are required .This device has advantage over standard turbopumps in that the wt. is about the same, the unit,engg.and test costs are less and the chance for catastrophic failure is less.This pump has the advantage over pressure fed designs in that the wt. of the complete rocket is much less, and the rocket is much safer because the tanks of rocket fuel do not need to be at high pressure.The pump could be started after being stored for an extended period with high reliability.It can be used to replace turbopumps for rocket booster opn. or it can be used to replace high pressure tanks for deep space propulsion.It can also be used for satellite orbit changes and station keeping.

Performance Validation:

A calculation of the weight of this type of pump shows that the power to weight ratio would be dominated by the pressure chamber and that it would be of the order of 8-12 hp per lb., for a 5 second cycle using a composite chamber. This performance is similar to state of the art gas-generator turbopump technology. (The F1 turbopump on the Saturn V put out 20 hp/lb) This pump could be run until dry, so it would achieve better residual propellant scavenging than a turbopump. This system would require a supply of gaseous or liquid Helium which would be heated by a heat exchanger mounted on the combustion chamber before it was used to pressurize the fuel, as in the Ariane rocket.. The volume of gas required would be equivalent to a standard pressure fed design, with a small additional amount to account for ullage in the pump chambers. The rocket engine itself could be a primarily ablative design, as in the NASA Fastrac, scorpious rocket or in recent rocket engine tests.