Turbo-Charger

A turbocharger is actually a type of supercharger. Originally, the turbocharger was called a “turbo super charger.” Obviously, the name was shortened out of convenience.

A turbocharger’s purpose is to compress the oxygen entering a car’s engine, increasing the amount of oxygen that enters and thereby increasing the power output. Unlike the belt-driven supercharger that is normally thought of when one hears the word “supercharger,” the turbocharger is powered by the car’s own exhaust gases. In other words, a turbocharger takes a by-product of the engine that would otherwise be useless, and uses it to increase the car’s horsepower.

Cars without a turbocharger or supercharger are called normally aspirated. Normally aspirated cars draw air into the engine through an air filter; the air then passes through a meter, which monitors and regulates the amount of air that enters the system. The air is then delivered to the engine’s combustion chambers, along with a controlled amount of fuel from the carburetor or fuel injectors.

In a turbocharged engine, however, the air is compressed so that more oxygen will fit in the combustion chamber, dramatically increasing the burning power of the engine. The turbocharger is composed of two main parts: the compressor, which compresses the air in the intake; and the turbine, which draws the exhaust gases and uses them to power the compressor. Another commonly used term in relation to turbochargers is boost, which refers to the amount of pressure the air in the intake is subjected to; in other words, the more compressed the air is, the higher the boost.

Although the increase in power is advantageous to the car — and likely a source of enjoyment for the driver — a turbocharger has its drawbacks. First and foremost, a turbocharged engine must have a lower compression ratio than a normally aspirated engine. For this reason, one cannot simply put a turbocharger on an engine that was intended for normal aspiration without seriously undermining the life and performance of the engine. Also, a lower compression ratio means the engine will run less efficiently at low power.

Another major drawback of a turbocharger is the phenomenon known as turbo lag. Because the turbocharger runs on exhaust gases, the turbine requires a build-up of exhaust before it can power the compressor; this means that the engine must pick up speed before the turbocharger can kick in. Additionally, the inlet air grows hotter as it is compressed, reducing its density, and thereby its efficiency in the combustion chamber; a radiator-like device called an intercooler is often used to counter this effect in turbocharged engines.

Dual Fuel System

This hydrogen engine takes advantage of the characteristics of Mazda’s unique rotary engine and maintains a natural driving feeling unique to internal combustion engines. It also achieves excellent environmental performance with zero CO2 emissions.

Further, the hydrogen engine ensures performance and reliability equal to that of a gasoline engine. Since the gasoline version requires only a few design changes to allow it to operate on hydrogen, hydrogen-fueled rotary engine vehicles can be realized at low cost. In addition, because the dual-fuel system allows the engine to run on both hydrogen and gasoline, it is highly convenient for long-distance journeys and trips to areas with no hydrogen fuel supply.

Technology of the RENESIS Hydrogen Rotary Engine:

The RENESIS hydrogen rotary engine employs direct injection, with electronically-controlled hydrogen gas injectors. This system draws in air from a side port and injects hydrogen directly into the intake chamber with an electronically-controlled hydrogen gas injector installed on the top of the rotor housing. The technology illustrated below takes full advantage of the benefits of the rotary engine in achieving hydrogen combustion.

 

 

RE Features suited to Hydrogen Combustion

In the practical application of hydrogen internal combustion engines, avoidance of so-called backfiring (premature ignition) is a major issue. Backfiring is ignition caused by the fuel coming in contact with hot engine parts during the intake process. In reciprocal engines, the intake, compression, combustion and exhaust processes take place in the same location—within the cylinders. As a result, the ignition plugs and exhaust valves reach a high temperature due to the heat of combustion and the intake process becomes prone to backfiring.
In contrast, the RE structure has no intake and exhaust valves, and the low-temperature intake chamber and high-temperature combustion chamber are separated. This allows good combustion and helps avoid backfiring.
Further, the RE encourages thorough mixing of hydrogen and air since the flow of the air-fuel mixture is stronger and the duration of the intake process is longer than in reciprocal engines.

Combined use of Direct Injection and Premixing

Aiming to achieve a high output in hydrogen fuel mode, a direct injection system is applied by installing an electronically-controlled hydrogen gas injector on the top of the rotor housing. Structurally, the RE has considerable freedom of injector layout, so it is well suited to direct injection.
Further, a gas injector for premixing is installed on the intake pipe enabling the combined use of direct injection and premixing, depending on driving conditions. This produces optimal hydrogen combustion.
When in the gasoline fuel mode, fuel is supplied from the same gasoline injector as in the standard gasoline engine.

 

Adoption of Lean Burn and EGR

Lean burn and exhaust gas recirculation (EGR) are adopted to reduce nitrogen oxide (NOx) emissions. NOx is primarily reduced by lean burn at low engine speeds, and by EGR and a three-way catalyst at high engine speeds. The three-way catalyst is the same as the system used with the standard gasoline engine.
Optimal and appropriate use of lean burn and EGR satisfies both goals of high output and low emissions. The volume of NOx emissions is about 90 percent reduced from the 2005 reference level.

Dual Fuel System

When the system runs out of hydrogen fuel, it automatically switches to gasoline fuel. For increased convenience, the driver can also manually shift the fuel from hydrogen to gasoline at the touch of a button.

Latest Placement Papers in Mechanical

• WHAT IS THE DIFFERENCE BETWEEN RATED SPEED AND ECONOMIC SPEED?

THE RATED SPEED TELLS US ABOUT THE MAXIMUM SPEED WHICH CAN BE ACHIEVED BY A VEHICLE OR SOME OTHER MACHINE BUT THE ECONOMICAL SPEED MEANS THE SPEED LIMIT AT WHICH THE MACHINE WORKS EFFICIENTLY WITH LEAST CONSUMPTION OF FUEL.EG-IN NORMAL BIKES(NOT RACING),THE MAX.SPEED LIMIT SHOWN ON SPEEDOMETER IS UPTO 120 KMPH BUT COMPANIES ALWAYS ADVICE THEIR CUSTOMERS TO DRIVE SUCH BIKES AT AROUND 60 KMPH TO HAVE MAXIMUM MILEAGE.

• What is the purpose of scrapper ring

scrap the excess lube oil from the cylinder walls.there by preventing oil from entering combustion zone.

• What are the causes of main engine black smoke?

There is many cause of black smoke.

1.is improper mixture of fuel supply by carburetor like very rich mixture so the fuel improper burn.

2. it is when piston or piston ring is fail so back side cooling oil release in combustion chamber it cause black smoke.

3.improper ignition system like not sufficient time of pressure rise delay period .

• how cooling tower height selected?

The Function of a cooling tower is to cool the water coming from condenser.The water coming from condenser is hot and it is sprayed in a cooling tower and a air coming out from bottom cool the water which is coming down.Outside air is cool and air in inside the cooling tower is hot due to humidity.So there is a density difference between outside and inside air which caused pressure difference.

Pr Difference = g x H x ( density difference)

Where,

H = Height of chimney

Pr Difference = Pr Difference so that air can flow to cooling tower from outside

• How does axial thrust balance in multistage pump?

A BALANCING LINE FROM DISCHARGE END IS CONNECTED TO SUCTIONSIDE TO BALANCE AXIAL THRUST.

• how to calculate the boiler efficiency?any formula is there?

boiler efficiency= (heat transferred to feed water inconverting it to steam)/(heat released by completecombustion of fuel)

n(eta)= Mass of steam * (h- H(water))/(mass of fuel *calorific value fuel)

• What is the significance of torque(in N-m) given in the engine specification

it give the moment about any point or simple rotation.

• what is the exact requirement of priming?

priming is done in pumps to remove the entrapped air from the suction pipe thus aiding in smooth operation and avoiding in excess load on the pump.

• What is the use of a PULLEY?

transmission of power(force) in rotary form

• why does cycle rim don’t bend even in heavy loads?

Because of rubber tires. The load is distributed and its effect reduces i.e. tires absorbs heavy load and shocks with the support of steel rim.

The rim has many spokes. The spokes distribute the load equally and the rubber tires absorb more than half of the load.

• How tonnage can be controlled in PLC base hydraulic press

customintegration of press interlocks to interfacingwith other parts of the hydraulic press line such as thefeeder or transfer systems.

• what is BHP?

Brake horsepower is the amount of work generated by a motor under ideal conditions. This work is calculated without the consideration of effects of any auxiliary component, that may slow down the actual speed of the motor. Brake horsepower is measured within the engines output shaft and was originally designed to calculate and compare the output of steam engines.

As per the conventions, 1 BHP equals to:

• 745.5 watts
• 1.01389 ps
• 33,000 ft lbf/min
• 42.2 BTU/min

DISI ENGINE

In developing the DISI engine, we aimed to cool the interior of the cylinder as much as possible by promoting fuel vaporization and uniform mixing of atomized fuel and air. This produces a high charging efficiency of the air-fuel mixture and a high compression ratio, which results in significant improvements in both torque and fuel efficiency.

Characteristics of the direct injection engine:

• Fuel is injected from a tiny nozzle into a relatively large cylinder, so it has a high latent heat of vaporization, which efficiently cools the air within (in-cylinder cooling effect).

• The air temperature in the cylinder decreases, which means:

• (1) more air may be charged into the combustion chamber, which produces increased torque.

• (2) the engine is less prone to knocking. This contributes to increased torque, and enables a higher compression ratio that also contributes to good fuel efficiency.

In a direct injection engine, however, the fuel skips the waiting period it would have to endure inside a standard engine and instead proceeds straight to the combustion chamber. This allows the fuel to burn more evenly and thoroughly. For the driver, that can translate to better mileage and greater power to the wheels.

In the past, direct injection posed too many technical hurdles to make it worthwhile for mass market gasoline automobiles. But with advances in technology and greater pressure to make cars run more cleanly and efficiently, it looks as if gasoline direct injection — or GDI as it’s referred to in industry lingo — is here to stay. In fact, most of the major car manufacturers make or plan to soon introduce gasoline cars that take advantage of this fuel saving and performance enhancing system.