elective 2 term paper...toti

8/7/2019 elective 2 term paper...toti

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University of Southeastern PhilippinesObrero campus, Davao City

College of Engineering

In partial fulfillment of the requirements

in the subject of Elective 2

Submitted by:

Irwin Glenn O. JabagatBSME-5

Submitted to:

Dr. Roselio Lyndon Roble, PME, FPSME


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Diesel elements

Definition:

A diesel engine (also known as a compression ignition engine and sometimes capitalized

asDiesel engine) is an internal combustion engine that uses the heat of compression to

initiateignition to burn the fuel, which is injected into the combustion chamber during the final

stage of compression. This is in contrast to spark ignition engines such as a petrol engine (known

as agasoline engine in North America) or gas engine (using a gaseous fuel, not gasoline), which

uses a spark plug to ignite an air-fuel mixture. The diesel engine has the highest thermal

efficiency of any regular internal or external combustionengine due to its very high compression

ratio. Low-speed diesel engines (as used in ships and other applications where overall engine

weight is relatively unimportant) often have a thermal efficiency which exceeds 50 percent.

History:

The diesel engine is modelled on the Diesel cycleand the engine and thermodynamic cycle were

both developed by Rudolph Diesel in 1897. Rudolf Diesel, of German nationality, was born in

1858 in Paris where his parents were German immigrants. He was educated at Munich

Polytechnic. After graduation he was employed as a refrigerator engineer, but his true love lay in

engine design. Diesel designed many heat engines, including a solar-powered air engine. In 1892

he received patents in Germany, Switzerland, the United Kingdom and filed in the United States

for "METHOD OF AND APPARATUS FOR CONVERTING HEAT INTO WORK". In 1893

he published a paperdescribing a "slow-combustion engine" that first compressed air thereby

raising its temperature above the igniting-point of the fuel, then gradually introducing fuel while

letting the mixture expand "against resistance sufficiently to prevent an essential increase of

temperature and pressure", then cutting off fuel and "expanding without transfer of heat". In

1894 and 1895 he filed patents and addenda in various countries for his Diesel engine; the firstpatents were issued in Spain (No.16,654) France (No.243,531) and Belgium (No.113,139) in

December 1894, and in Germany (No.86,633) in 1895 and the United States (No.608,845) in

1898. He operated his first successful engine in 1897. His engine was the first to prove that fuel

could be ignited without a spark.


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Though best known for his invention of the pressure-ignited heat engine that bears his name,

Rudolf Diesel was also a well-respected thermal engineer and a social theorist. Diesel's

inventions have three points in common: they relate to heat transfer by natural physical processes

or laws; they involve markedly creative mechanical design; and they were initially motivated by

the inventor's concept of sociological needs. Rudolf Diesel originally conceived the diesel engine

to enable independent craftsmen and artisans to compete with industry.

At Augsburg, on August 10, 1893, Rudolf Diesel's prime model, a single 10-foot (3.0 m) iron

cylinder with a flywheel at its base, ran on its own power for the first time. Diesel spent two

more years making improvements and in 1896 demonstrated another model with a theoretical

efficiency of 75 percent, in contrast to the 10 percent efficiency of the steam engine. By 1898,

Diesel had become a millionaire. His engines were used to power pipelines, electric and water

plants, automobiles and trucks, and marine craft. They were soon to be used in mines, oil fields,

factories, and transoceanic shipping.

Types and Characteristics:

Two-stroke diesel engine

A two-stroke engine is an internal combustion engine that completes thethermodynamic cycle in

two movements of the piston (compared to twice that number for a four-stroke engine). This

increased efficiency is accomplished by using the beginning of the compression stroke and the

end of the combustion stroke to perform simultaneously the intake and exhaust (or scavenging)

functions. In this way two-stroke engines often provide strikingly high specific power. Gasoline

(spark ignition) versions are particularly useful in lightweight (portable) applications such as

chainsaws and the concept is also used in diesel compression ignition engines in large and non-

weight sensitive applications such as ships and locomotives.

Four-stroke diesel engine

The four strokes refer to intake, compression, combustion (power), and exhaust strokes that

occur during two crankshaft rotations per working cycle of the gasoline engine and diesel engine.


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The cycle begins at Top Dead Center (TDC), when the piston is farthest away from the axis of

thecrankshaft. A stroke refers to the full travel of the piston from Top Dead Center (TDC) to

Bottom Dead Center (BDC). (See Dead centre.)

Diesel Applications:

Passenger cars

Diesel engines have long been popular in bigger cars and this is spreading to smaller cars.

Diesel engines tend to be more economical at regular driving speeds and are much better at city

speeds. Their reliability and life-span tend to be better (as detailed). Some 40% or more of all

cars sold in Europe are diesel-powered where they are considered a low CO2 option. Mercedes-

Benz in conjunction with Robert Bosch GmbH produced diesel-powered passenger cars starting

in 1936 and very large numbers are used all over the world (often as "Grande Taxis" in the Third

World).

Railroad rolling stock

Diesel engines have eclipsed steam engines as the prime mover on all non-electrified

railroads in the industrialized world. The first diesel locomotives appeared in the early 20th

century, and diesel multiple units soon after.

While electric locomotives have now replaced the diesel locomotive almost completely

on passenger traffic in Europe and Asia, diesel is still today very popular for cargo-

hauling freight trains and on tracks where electrification is not feasible.

Most modern diesel locomotives are actually diesel-electric locomotives: the diesel

engine is used to power an electric generator that in turn powers electric traction engines with no

mechanical connection between diesel engine and traction.

Other transport uses

Larger transport applications (trucks, buses, etc.) also benefit from the diesel's reliability

and high torque output. Diesel displaced paraffin (or tractor vaporising oil, TVO) in most parts

of the world by the end of the 1950s with the U.S. following some 20 years later.


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In merchant ships and boats, the same advantages apply with the relative safety of diesel

fuel an additional benefit. The German pocket battleships were the largest diesel warships, but

the German torpedo-boats known as E-boats (Schnellboot) of the Second World War were also

diesel craft. Conventional submarines have used them since before the First World War, relying

on the almost total absence of carbon monoxide in the exhaust. American World War II diesel-

electric submarines operated on two-stroke cycle as opposed to the four-stroke cycle that other

navies used.

Military fuel standardisation

NATO has a single vehicle fuel policy and has selected diesel for this purpose. The use of

a single fuel simplifies wartime logistics. NATO and the United States Marine Corps have even

been developing a diesel military motorcycle based on a Kawasaki off road motorcycle, with a

purpose designed naturally aspirated direct injection diesel at Cranfield University in England, to

be produced in the USA, because motorcycles were the last remaining gasoline-powered vehicle

in their inventory. Before this, a few civilian motorcycles had been built using adapted stationary

diesel engines, but the weight and cost disadvantages generally outweighed the efficiency gains.

Current and Future Developments

As of 2008, many common rail and unit injection systems already employ new injectors

using stacked piezoelectric wafers in lieu of a solenoid, giving finer control of the injectionevent. Variable geometry turbochargers have flexible vanes, which move and let more air into

the engine depending on load. This technology increases both performance and fuel economy.

Boost lag is reduced as turbo impeller inertia is compensated for.

Accelerometer pilot control (APC) uses an accelerometer to provide feedback on the

engine's level of noise and vibration and thus instruct the ECU to inject the minimum amount of

fuel that will produce quiet combustion and still provide the required power (especially while

idling).

The next generation of common rail diesels is expected to use variable injection

geometry, which allows the amount of fuel injected to be varied over a wider range, and variable

valve timing (see Mitsubishi's 4N13 diesel engine) similar to that on petrol engines. Particularly

in the United States, coming tougher emissions regulations present a considerable challenge to


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diesel engine manufacturers. Ford's HyTrans Project has developed a system which starts the

ignition in 400 ms, saving a significant amount of fuel on city routes, and there are other

methods to achieve even more efficient combustion, such as homogeneous charge compression

ignition, being studied.

Figure:

Geothermal Elements

Definition:

Geothermal energy (from the Greek roots geo, meaning earth, and thermos, meaning heat)

is power extracted from heat stored in the earth. This geothermal energyoriginates from theoriginal formation of the planet, from radioactive decay of minerals, from volcanic activity and

from solar energy absorbed at the surface. It has been used for bathing since Paleolithic times

and for space heating since ancient Roman times, but is now better known for generating

electricity. Worldwide, about 10,715 megawatts(MW) of geothermal power is online in 24


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countries. An additional 28 gigawatts of directgeothermal heating capacity is installed for district

heating, space heating, spas, industrial processes, desalination and agricultural applications.[1]

Geothermal power is cost effective, reliable, sustainable, and environmentally friendly, but has

historically been limited to areas near tectonic plate boundaries. Recent technological advanceshave dramatically expanded the range and size of viable resources, especially for applications

such as home heating, opening a potential for widespread exploitation. Geothermal wells release

greenhouse gases trapped deep within the earth, but these emissions are much lower per energy

unit than those of fossil fuels. As a result, geothermal power has the potential to help

mitigate global warming if widely deployed in place of fossil fuels.

History:

Hot springs have been used for bathing at least since paleolithic times. The oldest known spa is a

stone pool on Chinas Lisan mountain built in the Qin dynasty in the 3rd century BC, at the same

site where the Huaqing Chi palace was later built. In the first century AD, Romans

conquered Aquae Sulis, now Bath, Somerset, England, and used the hot springs there to

feedpublic baths and underfloor heating. The admission fees for these baths probably represent

the first commercial use of geothermal power. The world's oldest geothermal district heating

system inChaudes-Aigues, France, has been operating since the 14th century. The earliest

industrial exploitation began in 1827 with the use of geyser steam to extract boric

acid from volcanic mud inLarderello, Italy.

Application:

In the geothermal industry, low temperature means temperatures of 300 F (149 C) or less.

Low-temperature geothermal resources are typically used in direct-use applications, such

as district heating, greenhouses, fisheries, mineral recovery, and industrial process heating.

However, some low-temperature resources can generate electricity using binary cycle electricity

generating technology.[8]


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Approximately 70 countries made direct use of 270 petajoules (PJ) of geothermal heating in

2004. More than half went for space heating, and another third for heated pools. The remainder

supported industrial and agricultural applications. Global installed capacity was 28 GW, but

capacity factors tend to be low (30% on average) since heat is mostly needed in winter. The

above figures are dominated by 88 PJ of space heating extracted by an estimated

1.3 million geothermal heat pumps with a total capacity of 15 GW.[1] Heat pumps for home

heating are the fastest-growing means of exploiting geothermal energy, with a global annual

growth rate of 30% in energy production.[9]

Direct heating is far more efficient than electricity generation and places less demanding

temperature requirements on the heat resource. Heat may come from co-generation via a

geothermal electrical plant or from smaller wells or heat exchangers buried in shallow ground.

As a result, geothermal heating is economic at many more sites than geothermal electricity

generation. Where natural hot springs are available, the heated water can be piped directly

into radiators. If the ground is hot but dry, earth tubes or downhole heat exchangers can collect

the heat. But even in areas where the ground is colder than room temperature, heat can still be

extracted with a geothermal heat pump more cost-effectively and cleanly than by conventional

furnaces.[10] These devices draw on much shallower and colder resources than traditional

geothermal techniques, and they frequently combine a variety of functions, including air

conditioning, seasonal energy storage, solar energycollection, and electric heating. Geothermal

heat pumps can be used for space heating essentially anywhere.

Geothermal heat supports many applications. District heating applications use networks of piped

hot water to heat many buildings across entire communities. In Reykjavk, Iceland, spent water

from the district heating system is piped below pavement and sidewalks to

meltsnow.[11]

Geothermal desalination has been demonstrated.

Performance Evaluation:

Geothermal power requires no fuel (except for pumps), and is therefore immune to fuel cost

fluctuations, but capital costs are significant. Drilling accounts for over half the costs, and

exploration of deep resources entails significant risks. A typical well doublet (extraction and


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injection wells) in Nevada can support 4.5 megawatts (MW) and costs about $10 million to drill,

wit

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ure

rate

.

In

tota

l,

elec

trical plant construction and well drilling cost about 2-5 million per MW of electrical capacity,

while the breakeven price is 0.04-0.10 per kWh.[18] Enhanced geothermal systems tend to be

on the high side of these ranges, with capital costs above $4 million per MW and breakeven

above $0.054 per kWh in 2007.[19] Direct heating applications can use much shallower wells

with lower temperatures, so smaller systems with lower costs and risks are feasible. Residential

geothermal heat pumps with a capacity of 10 kilowatt (kW) are routinely installed for around

$13,000 per kilowatt. District heating systems may benefit from economies of scale if demand

is geographically dense, as in cities, but otherwise piping installation dominates capital costs.

The capital cost of one such district heating system in Bavaria was estimated at somewhat over

1 million per MW.[20] Direct systems of any size are much simpler than electric generators and

have lower maintenance costs per kWh, but they must consume electricity to run pumps and

compressors. Some governments subsidize geothermal projects.

Figure:


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Fuel Systems

Definition:

The function of the fuel system is to store and supply fuel to the cylinder chamber where it can

be mixed with air, vaporized, and burned to produce energy. The fuel, which can be

either gasoline or diesel is stored in a fuel tank. A fuel pump draws the fuel from

the tank through fuel lines and delivers it through a fuel filter to either a carburetor or fuel

injector, then delivered to the cylinder chamber for combustion.

GASOLINE

Gasoline is a complex blend of carbon and hydrogen compounds. Additives are then added to

improve performance. All gasoline is basically the same, but no two blends are identical. The

two most important features of gasoline are volatility and resistance to knock (octane). Volatility

is a measurement of how easily the fuel vaporizes. If the gasoline does not vaporize completely,

it will not burn properly (liquid fuel will not burn).

If the gasoline vaporizes too easily the mixture will be too lean to burn properly. Since high

temperatures increase volatility, it is desirable to have a low volatility fuel for warm

temperatures and a high volatility fuel for cold weather. The blends will be different for summer

and winter fuels. Vapor lock which was a persistent problem years ago, exists very rarely today.


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In today's cars the fuel is constantly circulating from the tank, through the system and back to the

tank. The fuel does not stay still long enough to get so hot that it begins to vaporize. Resistance

to knock or octane is simply the temperature the gas will burn at. Higher octane fuel requires a

higher temperature to burn. As compression ratio or pressure increases so does the need for

higher octane fuel. Most engines today are low compression engines therefore requiring a lower

octane fuel (87). Any higher octane than required is just wasting money. Other factors that affect

the octane requirements of the engine are: air/fuel ratio, ignition timing, engine temperature, and

carbon build up in the cylinder. Many automobile manufacturers have

installed exhaust gas recirculation systems to reduce cylinder chamber temperature. If these

systems are not working properly, the car will have a tendency to knock. Before switching to a

higher octane fuel to reduce knock, make sure to have these other causes checked.

DIESEL

Diesel fuel, like gasoline is a complex blend of carbon and hydrogen compounds. It too requires

additives for maximum performance. There are two grades of diesel fuel used in automobiles

today: 1-D and 2-D. Number 2 diesel fuel has a lower volatility and is blended for higher loads

and steady speeds, therefore works best in large truck applications. Because number 2 diesel fuel

is less volatile, it tends to create hard starting in cold weather. On the other hand number 1 diesel

is more volatile, and therefore more suitable for use in an automobile, where there is constant

changes in load and speed. Since diesel fuel vaporizes at a much higher temperature than

gasoline, there is no need for a fuel evaporation control system as with gasoline. Diesel fuels are

rated with a cetane number rather than an octane number. While a higher octane of gasoline

indicates resistance to ignition, the higher cetane rating of diesel fuel indicates the ease at which

the fuel will ignite. Most number 1 diesel fuels have a cetane rating of 50, while number 2 dieselfuel have a rating of 45. Diesel fuel emissions are higher in sulfur, and lower in carbon monoxide

and hydrocarbons than gasoline and are subject to different emission testing standards.


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FUEL TANK

Tank location and design are always a compromise with available space. Most automobiles have

a single tank located in the rear of the vehicle. Fuel tanks today have internal baffles to prevent

the fuel from sloshing back and forth. If you hear noises from the rear on acceleration and

deceleration the baffles could be broken. All tanks have a fuel filler pipe, a fuel outlet line to the

engine and a vent system. All catalytic converter cars are equipped with a filler pipe restrictor so

that leaded fuel, which is dispensed from a thicker nozzle, cannot be introduced into the fuel

system. All fuel tanks must be vented. Before 1970, fuel tanks were vented to the atmosphere,

emitting hydrocarbon emissions. Since 1970 all tanks are vented through a charcoal canister, into

the engine to be burned before being released to the atmosphere. This is called evaporative

emission control and will be discussed further in the emission control section. Federal law

requires that all 1976 and newer cars have vehicle rollover protection devices to prevent fuel

spills.

FUEL LINES

Steel lines and flexible hoses carry the fuel from the tank to the engine. When servicing or

replacing the steel lines, copper or aluminum must never be used. Steel lines must be replaced

with steel. When replacing flexible rubber hoses, proper hose must be used. Ordinary rubber

such as used in vacuum or water hose will soften and deteriorate. Be careful to route all hoses

away from the exhaust system.

FUEL PUMPS

Two types of fuel pumps are used in automobiles; mechanical and electric. All fuel injected cars

today use electric fuel pumps, while most carbureted cars use mechanical fuel pumps.

Mechanical fuel pumps are diaphragm pumps, mounted on the engine and operated by an


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eccentric cam usually on the camshaft. A rocker arm attached to the eccentric moves up and

down flexing the diaphragm and pumping the fuel to the engine. Because electric pumps do not

depend on an eccentric for operation, they can be located anywhere on the vehicle. In fact they

work best when located near the fuel tank.

Many cars today, locate the fuel pump inside the fuel tank. While mechanical pumps operate on

pressures of 4-6 psi (pounds per square inch), electric pumps can operate on pressures of 30-40

psi. Current is supplied to the pump immediately when the key is turned. This allows for constant

pressure on the system for immediate starting. Electric fuel pumps can be either low pressure or

high pressure. These pumps look identical, so be careful when replacing a fuel pump that the

proper one is used. Fuel pumps are rated by pressure and volume. When

checking fuel pump operation, both specifications must be checked and met.

FUEL FILTERS

The fuel filter is the key to a properly functioning fuel delivery system. This is more true with

fuel injection than with carbureted cars. Fuel injectors are more susceptible to damage from dirt

because of their close tolerances, but also fuel injected cars use electric fuel pumps. When the

filter clogs, the electric fuel pump works so hard to push past the filter, that it burns itself up.

Most cars use two filters. One inside the gas tank and one in a line to the fuel injectors or

carburetor. Unless some severe and unusual condition occurs to cause a large amount of dirt to

enter the gas tank, it is only necessary to replace the filter in the line.

Types:

Mechanical

The term Mechanical when applied to fuel injection is used to indicate that metering

functions of the fuel injection (how the correct amount of fuel for any given situation is

determined and delivered) is not achieved electronically but rather through mechanical means

alone.


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information about the Bendix system in December 1956 was followed in March 1957 by a price

bulletin that pegged the option at US$395, but due to supplier difficulties, fuel-injected Rebels

would only be available after June 15. This was to have been the first production EFI engine, but

Electrojector's teething problems meant only pre-production cars were so equipped: thus, very

few cars so equipped were ever sold and none were made available to the public. The EFI system

in the Rambler was a far more-advanced setup than the mechanical types then appearing on the

market and the engines ran fine in warm weather, but suffered hard starting in cooler

temperatures.

Figure:


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DIESEL POWER PLANT

Diesel plants are more efficient than any other heat engine of comparable size. Diesel

power plant issuitable for small and medium outputs (2-50MW). These power plants are suitable

for peak load power requirements, fuel cost are favour and where the water scarcity present. Itcan be started very quickly and immediately generate the electric power.

The major components of the plant are:

a) Engine

Engine is the heart of a diesel power plant. Engine is directly connected through a gear

box to the generator. Generally two-stroke engines are used for power generation. Now a day,

advanced super & turbo charged high speed engines are available for power production.

b) Air supply system

Air inlet is arranged outside the engine room. Air from the atmosphere is filtered by air

filter and conveyed to the inlet manifold of engine. In large plants supercharger/turbocharger is

used for increasing the pressure of input air which increases the power output.


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c) Exhaust System

This includes the silencers and connecting ducts. The heat content of the exhaust gas is

utilized in a turbine in a turbocharger to compress the air input to the engine.

d) Fuel System

Fuel is stored in a tank from where it flows to the fuel pump through a filter. Fuel is

injected to the engine as per the load requirement.

e) Cooling system

This system includes water circulating pumps, cooling towers, water filter etc. Cooling

water is circulated through the engine block to keep the temperature of the engine in the safe

range.

f) Lubricating system

Lubrication system includes the air pumps, oil tanks, filters, coolers and pipe lines.

Lubricant is given to reduce friction of moving parts and reduce the wear and tear of the engine

parts.

g) Starting System

There are three commonly used starting systems, they are;

1) A petrol driven auxiliary engine,

2) Use of electric motors,

3)Use of compressed air from an air compressor at a pressure of 20 Kg/cm.

h) Governing system

The function of a governing system is to maintain the speed of the engine constant

irrespective of load on the plant. This is done by varying fuel supply to the engine according to

load.

Advantages of diesel power plants

1. More efficient than thermal plant

2. Design, Layout etc are simple and cheap

3. Part load efficiency is very high

4. It can be started quickly

5. Simple & easy maintenance

6. No problem with fuel & dust handling


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7. It can be located in the heart of town

8. Less cooling water required.

Disadvantages

1. There is a limitation for size of a diesel engine

2. Life of plant is comparatively less

3. Noise pollution is very high

4. Repair cost is very high

5. High lubrication cost

Steam is used for heating and process work as it isan ideal carrier of heat. Its three

main advantagesas a heat transfer medium are as follows:

It transfers heat at constant temperature.This is extremely useful whendealing with

heat sensitive materials.The temperature of steam is dependentupon the steam

pressure.This results ina simple method of temperature control.It is compact in terms of

heat content perunit volume.This means heat can heconveyed in simple piping systems.

Steam has many uses in industry. It is used for process heating, pressure control,

mechanical drive, component separation and is a source of water for many process reactions.

Steam has many performance advantages that make it an attractive means of delivering energy

including low toxicity, ease of transportability, high efficiency, high heat capacity and low cost

relative to other alternatives.

Steam systems provide process heating, pressure control, mechanical drive, component

separation, and are a source of water for many process reactions. In 1994, US industries used

about 5,676 trillion Btu of steam energy, which represents about 34 percent of the total energy

used in industrial applications for product output 1. Steam use is especially significant in the pulp

and paper (2,197 trillion Btu), chemical (1,855 trillion Btu), and petroleum refining (1,373

trillion Btu), representing 83 percent, 57 percent, and 42 percent respectively of the total energy

used by theses industries.


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Figure:


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