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.

PRODUCE ELECTRICITY FROM SOLAR HEAT

The principles of solar thermal power conversion have been known for more than a century; its commercial scale-up and exploitation, however, has only taken place since the mid 1980s. With these first large-scale 30-80 MW parabolic trough power stations, built in the California Mojave desert, the technology has impressively demonstrated its technological and economic promise. With few adverse environmental impacts and a massive resource, the sun, it offers an opportunity to the countries in the sun belt of the world comparable to that currently being offered by offshore wind farms to European and other nations with the windiest shorelines.

Solar thermal power can only use direct sunlight, called ‘beam radiation’ or Direct Normal Irradiation (DNI), i.e. that fraction of sunlight which is not deviated by clouds, fumes or dust in the atmosphere and that reaches the earth’s surface in parallel beams for concentration. Hence, it must be sited in regions with high direct solar radiation. Suitable sites should receive at least 2,000 kilowatt hours (kWh) of sunlight radiation per m²annually, whilst best site locations receive more than 2,800 kWh/m²/year.

In many regions of the world, one square kilometer of land is enough to generate as much as 100-130 Giga watt hours (GWh) of solar electricity per year using solar thermal technology. This is equivalent to the annual production of a 50 MW conventional coal- or gas-fired mid-load power plants. Over the total life cycle of a solar thermal power system, its output would be equivalent to the energy contained in more than    5 million barrels of oil²).

TURNING SOLAR HEAT INTO ELECTRICITY

Producing electricity from the energy in the sun’s rays is a straightforward process: direct solar radiation can be concentrated and collected by a range of Concentrating Solar Power (CSP) technologies to provide medium- to high temperature heat.

This heat is then used to operate a conventional power cycle, for example through a steam turbine or a Stirling engine. Solar heat collected during the day can also be stored in liquid or solid media such as molten salts, ceramics, concrete or, in the future, phase-changing salt mixtures. At night, it can be extracted from the storage medium thereby continuing turbine operation.

MECHANICAL ENGG QUESTIONS-2

• Different between technology & engineering?

Engineering is application of science. Technology shows various methods of Engineering. A bridge can be made by using beams to bear the load,by an arc or by hanging in a cable; all shows different technology but comes under civil engineering and science applied is laws of force/load distribution.

• how a diesel engine works in generator?

Diesel engine is a prime mover,for a generator,pump,and for vehicles etc.generator is connected to engine by shaft.mostly in thermal power plat ,there is an engine is used to drive generator to generate power.

• WHAT IS THE OTHER NAME OF MICROMETER & VERNIER CALLIPER

Micrometer’s other name is Screw Gauze & Vernier caliper’s other name is slide caliper.

• What is flashpoint?

Flash point: the lowest temperature at which the vapor of a combustible liquid can be ignited in air.

• what is basic difference between impulse turbine and reaction turbine?

In impulse turbine, jet is used to create impulse on blades
which rotates the turbine and in reaction turbine, no jet
is used pressure energy is converted into kinetic energy.

In impulse turbine fluid enter& leave with same energy ,but in reaction turbine fluid enter with pressure energy&
leaves with kinetic energy

In impulse turbine all the pressure drops in nozzle only &
in reaction turbine pressure drops both fixed & moving
blades.the difference is due to blade profiles.

• What is the need for drafting?

Drafting is the allowance give to casting process.it also used to remove the casting from mould without damage of
corners.

• what is the difference between BSP thread and BSW thread?

The British Standard Pipe thread (BSP thread) is a family
of standard screw thread types that has been adopted
internationally for interconnecting and sealing pipe ends
by mating an external (male) with an internal (female) thread.
British Standard Whitworth (BSW) is one of a number of
imperial unit based screw thread standards which use the
same bolt heads and nut hexagonal sizes.

• What is refrigerant?

Any substance that transfers heat from one place to another,
creating a cooling effect. water is the refrigerant in absorption machines.

• The amount of carbon present in Cast Iron

Carbon is basically present in the form of cementite in cast iron.Its percentage lies in the range of 2.03-6.67(% by weight of cementite for Cast Iron.If the amount is less than the above range than it is stainless steel.

• What are the loads considered when designing the Nut and Bolts?

Shear Loads & crushing loads

• what is the effect of reheat on rankine cycle? 1.efficiency increases 2.work output increases 3. both 4. none of these.

1.Efficiency increases.

this prevents the vapor from condensing during its expansion which can seriously damage the turbine blades, and improves the efficiency of the cycle, as more of the heat flow into the cycle occurs at higher temperature.