Some Power Sources Compared
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Watt
Reciprocating Steam Engine |
Various Rotory Engines (Wankel
and others) |
See http://inventors.about.com/library/inventors/bljjetenginehistory.htm |
Electric
Motor |
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Efficiency |
Multiple expansion
steam engines greatly improved efficiency. Now about 17% |
Most automotive and small
aircraft engines have 25-30% thermal efficiency. |
Ideal diesel efficiency of 56% |
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Has the potential to
be more efficient than a gasoline or diesel engine |
-stationary
gas turbines can reach an efficiency of about 40% - They can be particularly
efficient when waste heat from the gas turbine is recovered by a conventional
steam turbine in a process known as a combined
cycle. Efficiencies
of 60%+ can be realized |
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Inventor |
James Watt -1736 - 1819 |
Rudolph
Diesel 1858-1913 |
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Robert
Stirling 1790-1876 |
See below |
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1888 - Nikola Tesla (1867-1943) invents the first practicable AC motor
and polyphase power transmission system, which
revolutionizes industry and commerce. |
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Key Dates |
1776 – Watt built an engine with a
cylinder of 127 cm diameter to pump water 1778 - final version of the new Watt
engine 1782 - Watt made his double-acting
engine With this improvement the engine had double the power with
the same displacement 1807 - First commercially
successful river boat the North River
Steamboat (often called the "Clermont"). 1838 - The side-wheel paddle
steamer SS Great Western was the first purpose-built
steamship to initiate regularly scheduled trans-Atlantic crossings. |
1882 – Parsons brought out his
reaction steam turbine 1894 Parsons took out patent No.
394 for 'Propelling a vessel by means of a steam turbine….” 1897 – Turbinia
demonstrates speed potential of marine steam turbine 1898 - HMS Viper first steam
turbine powered warship 1906 Dreadnought, most powerful war ship in the world used steam
turbines 1906-7 Cunard sister ships turbine-driven Mauritania and Lusitania fastest liners on Atlantic |
first demonstrated by Nikolaus Otto in 1876 1885 Gottlieb Daimler and Wilhelm Maybach patented one of the first successful high-speed
internal-combustion engines and developed a carburetor allowing use of
gasoline as fuel. |
- patent for the device on February
23, 1893 and building
a functional prototype in early 1897 which went into production - SELANDIA
(1912) - 1923/24 the first diesel-driven
trucks - 1936 series production of the
first car diesel engine - 1924 first diesel switching
engines. 1930 Diesel engines suitable for
main line locomotives developed in Germany and 1939 – GM started mass production
of diesel mainline locomotives 1935 - first
heavy-oil burning four-stroke diesel. |
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1816 he received his first patent
for a new type of "air engine". |
1791 - John Barber received the first patent for a basic turbine
engine. His design was planned to use as a method of propelling the
'horseless carriage.' The turbine was designed with a chain-driven,
reciprocating type of compressor. It has a compressor, a combustion chamber,
and a turbine. 1872 - Dr. F. Stolze designed the
first true gas turbine engine. His engine used a multi-stage turbine section
and a flow compressor. This engine never ran under its own power. 1903 - Aegidius Elling of Norway built the first successful gas turbine
using both rotary compressors and turbines - the first gas turbine with excess power. 1897 - Sir
Charles Parson patented a steam turbine which was used to power a ship. 1914 - Charles Curtis filed the first application for a gas
turbine engine. 1918 - General Electric company started a gas turbine
division. Dr. Stanford A. Moss developed the GE turbosupercharger
engine during W.W.I. It used hot exhaust gases from a reciprocating engine to
drive a turbine wheel that in turn drove a centrifugal compressor used for
supercharging. 1920 - Dr. A. A. Griffith developed a theory of turbine
design based on gas flow past airfoils rather than through passages. 1930 - Sir
Frank Whittle (1907-1996) in England patented a design for a gas turbine for jet
propulsion. The first successful use of this engine was in April, 1937.
His early work on the theory of gas propulsion was based on the contributions
of most of the earlier pioneers of this field. 1936 - At the same time as Frank Whittle was working in 1939 - Heinkel Aircraft flew the
first flight of a gas turbine jet, the HE178. 1941 - Sir Frank Whittle designed the first successful
turbojet airplane, the Gloster Meteor, flown over
Great Britain. Whittle improved his jet engine during the war, and in 1942 he
shipped an engine prototype to General Electric in the United States.
America's first jet plane was built the following year. 1942 - Dr. Franz Anslem developed the axial-flow turbojet, Junkers Jumo 004, used in the Messerschmitt Me 262, the world's
first operational jet fighter. |
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1821 – Faraday’s first motor
1834 - |
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Prospects |
The reciprocating
steam engine powered the industrial revolution. As latye as World
War II it was being us3ed to power Liberty Ships. However, it seems to have no future even
though, using modern materials the steam locomotive might be made competitive
with today’s diesels (see A blast
from the past, Economist Dec 17th 1998). |
Steam turbines are no longer
competitive with diesel units for commercial marine propulsion or with gas
turbines for non-nuclear naval ships. In nuclear ships, all of which are naval, nuclear
energy is used to generate steam to power steam turbines. However, nuclear energy does not seem set
to be used in commercial shipping. Combined cycle gas
and steam turbine systems may have a future in shipping. |
Being challenged by fuel cells in
the key automotive sector. |
- Diesel engines have become
dominant for railway and marine propulsion, heavy machinery and heavy
vehicles. - Outside of North America,
electricity is preferred to diesel on high volume railway lines. - the future role of diesels in
light vehicles and small-scale power generation is unclear |
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Continue to be used for
specialized tasks |
The two major application areas of
gas-turbine engines are aircraft propulsion and electric power generation.
Gas turbines are used as stationary power plants to generate electricity as
stand-alone units or in conjunction with steam power plants on the
high-temperature side. In these plants, the exhaust gases serve as a heat
source for the steam. Steam power plants are considered external-combustion
engines, in which the combustion takes place outside the engine. The thermal
energy released during this process is then transferred to the steam as heat Gas turbines, in the form of
turbofan engines are dominant as aircraft power units. Combined cycle power plants are well
established in power generation and gas turbine emergency generators compete
with diesel units. Gas turbines have
not competed successfully with diesel and electricity in railway oservicerailways. |
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Unlimited |
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Comments |
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Frequently the output of diesel (eg. locomotives), steam turbine (power plants) and gas turbines
(small generating sets and combined cycle power plants) are converted to
electricity which may be used to drive electric motors. This is almost always true for locomotive
diesels. |
Sept 2004
“TYPES AND CHARACTERISTICS OF POWER SOURCES
All
of the marine power plants currently in use and under contemplation for future use can be classified according to the following basic thermodynamic cycles:
1. Rankine cycle-Steam turbines of
2,000-100,000 SHP/unit
2. Brayton cycle-Gas turbines of 500-40,000
SHP unit
3. Otto
cycle-Reciprocating internal-combustion gasoline engines of 10-2,000
SHP/unit
12-20. Speed-power trends for ship-type
ranges
4. Diesel
cycle-Reciprocating internal-combustion
diesel engines ….
STEAM
TURBINES
The
steam turbine is well suited to the largest power plants, produces a uniform turning effort, burns the
least expensive fuel, and is capable of
relatively high efficiencies, long
endurance, long life, long mean time between
overhaul (MTBO), and reasonable maintenance. It has the inherent disadvantages of large space requirements, a large watch-standing force, slow response time,
being slow in getting under way, intermediate energy conversion with its secondary working substance, mechanical non-reversibility, and high turbine speed. These latter two disadvantages necessitate
a separate, low-efficiency astern turbine of
reduced power and large, heavy reduction gearing to the propeller
shafts. The speed reduction is needed to
allow both the turbine and the propeller
to operate in their most efficient speed range.
GAS
TURBINES
Gas
turbines are powering an increasing number of high-speed displacement
ships and the majority of high-performance vessels.
This is because they have the lowest ratio
of machinery weight to horsepower (specific weight) of any of the marine power plants. Gas turbines are
very reliable …, provide quick response after a cold start, and are adaptable to remote-control operation with a small
watch-standing force. There is little
maintenance between overhauls and most
installations are designed to replace the
entire engine, much like the aircraft jet engine
from which it was derived. The disadvantages of gas-turbine propulsion include a large volume for the total plant, most of which is taken up by the inlet
and exhaust ducting for the large
quantities of air and exhaust gases.
Although the gas turbine is reasonably efficient at the design power rating, it has a very high
specific fuel consumption off the design rpm.
It also has no reversing capability, so
controllable pitch propellers are almost always found in gas-turbine
powered ships.
To improve fuel consumption at cruising speeds
in twin-screw vessels, one of the controllable pitch propellers is often
"feathered," or aligned with the
flow, so the shaft does not rotate and all of the propulsion comes from the remaining shaft.
Gas
turbines are perhaps most sensitive to atmospheric air temperature. Their power output will drop as inlet air temperature climbs. At the same time, the
steam cycle's efficiency drops when the cooling
water temperature in the condenser rises,
which is also a function of
its operating environment. It should also be pointed out that gas-turbine costs may be as much as
30 percent greater than those for steam power
plants, since the gas turbine burns a
higher grade fuel.
DIESEL
ENGINES
The
low-speed, direct-coupled diesel engine is the most efficient of all the marine power plants, with specific
fuel consumptions as low as 0.29 Ib/hp-hr. … it is
being used to power most new merchant
ships ….”
From Introduction to Naval Architecture BY THOMAS C. GILLMER AND BRUCE
JOHNSON, NAVAL INSTITUTE PRESS, 1982
“It is probable that attention was first given to the idea of a
practical internal combustion turbine in the early years of the present
century. In 1906 M Rene Armengaud converted a de laval impulse turbine to operate
on compressed air mixed with metered quantities of petroleum vapour, the mixture being fired by means of an incandescent
platinum wire igniter The useful output was about 30hp.
“Inevitably, the designer came up against the problem of the high gas
temperature which was to prevent any
significant
advance in practical gas turbine design until the developments in metallurgy
engendered by the 1939-45 war. Combustion took place at about 1800 deg C in Armengaud's machine, and the combustion
chamber
was lined with carborundum. Steam produced in a steam
coil within the chamber was mixed with the gas products to bring the turbine
inlet temperature down to about 400 deg C.
“In addition to the work by Armengaud and
others in France, the gas turbine received considerable attention in Germany,
where in 1910 Holzwarth designed and built. with the help of Korting Bros and
the Brown Boveri company, a vertical constant-volume
turbine designed to deliver 1000hp; it was coupled directly to a dc electric generator mounted above the turbine.
Instead of the continuous-combustion principle of the Armengaud
turbine, ignition in the Holzwarth machine was
initiated by a spark generated by high-tension magneto, and the hot gases were
passed to a two-stage Curtis impulse power turbine. Steam generated by
otherwise waste heat was used to drive a turbo-compressor supplying the
combustion air, absorbing a great part of the theoretical total output, and the
useful power amounted only to about 160hp.
“Development work came to a halt during the 1914-18 war but it was
resumed in 1918 in the wake of interest
shown by
the Prussian State Railway administration. In the following year an order was
placed for a 500bhp unit driving a dc generator. At about the same time
consideration was first given to the use of an internal-combustion turbine for
marine propulsion and in December 1920 a Holzwarth
unit, arranged for mechanical drive through reduction gears instead of
electrical drive, was delivered for trials.
“Like modern machines, the marine turbine had a number of equally
spaced combustion chambers (in its case six) arranged around the horizontal
shaft; as in the earlier Holzwarth design, the air
compressor was driven by a steam turbine utilising the exhaust gas heat for
steam generation. The design of a …
turbine of this type for marine propulsion was illustrated and discussed in The
Motor Ship for May 1922, but at berst the machine was
regarded only as a possible competitor for the steam turbine.
“As it turned out, the complexity of the Holzwarth
design and doubts about its material reliability militated against any further
commercial development of the marine gas turbine for another quarter of a
century.
“Apart from the lack of suitable materials for use in a
high-temperature environment, the early gas turbines also suffered from
inefficient compressor design. Between the wars, however, the Parsons Marine
Steam Turbine Co in
compressor
of the axial-flow type and thus the way was opened for the development of the
small gas turbine for auxiliary power drives.
“Elsewhere, with the added impetus generated by the impending war, the
gas turbine was under development as an aircraft jet engine and in 1941 Sir
Frank Whittle produced his first successful aero
gas
turbine. In the meantime, however, research work continued on the development
of what was essentially an internal combustion version of the marine steam
turbine, since advantages were seen in its basic simplicity compared with the
diesel engine and the fact that it could be run on a wide range of fuels.
Compared with the aircraft gas turbine, such machines were heavy and
comparatively slow running
but that
was considered to be no great drawback; it was expected that engine life to
worn-out condition would greatly exceed that of the aircraft jet engine and
that on-board maintenance demands would be small.
“In Britain, Metropolitan-Vickers Ltd was well to the forefront in the
design and development of gas turbines of the marine steam turbine-derived
type. In 1951 a 1200hp unit was installed for comparative trials in place of
one of the four diesel propulsion engines in the 12,000-ton (deadweight)
single-screw diesel-electric tanker Auris ….
The gas turbine unit, which burned diesel or the heavier residual fuel oils,
proved reliable in service and in March 1952 the Auris
crossed the Atlantic using only the gas turbine-driven alternator and
burning furnace fuel oil. No great problems were encountered and the vessel was
able to maintain an average speed of 7.25 knots.
“In all, the Metrovick machine ran for about
20,000 hours….”
From The
Illustrated History of Ships edited by E L Cornwell, Octopus Books 1979
“In
the 1970s, a significant number of ships were powered by steam turbines. But
during the 1980s and 1990s, diesel engines swept the field, because they
permitted substantial savings in fuel costs. American President Lines next
generation of container ships, the C-10's, are powered by diesels, and achieved
a 60% savings in fuel use over the steam turbine-powered C-8's. The last
edition of Containerisation International
Yearbook, which lists all container vessels in mZmmercial
service or under construction, reveals that only several hundred of the over
7,000 container ships in service were powered by steam turbine engines.”
From http://www.sdearthtimes.com/et0301/et0301s16.html
“ALTERNATIVE TO MARINE DIESEL ENGINES
There are no alternatives to small and medium size diesel engines in marine applications.
Over the last several years, gas
turbine engines have begun to be used as an alternative to large slow-speed
diesels. Gas turbine use of lighter distillate fuels provides lower emissions.
Although gas turbines have been used in military vessels for many years, it is
only recently that they are being installed in large ocean-going commercial
vessels. Their commercial reliability is yet to be seen.”
from http://www.dieselforum.org/background/marineapplications.html