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Topic: Thermodynamic cycle

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Power From the Sun - Chapter 12 The ultimate limitation placed on this process by the second law of thermodynamics is that no power cycle can convert more heat into work than the Carnot cycle.  A Carnot cycle is a hypothetical engine involving four processes: an adiabatic reversible compression and expansion and a constant temperature heat addition and rejection. A closed feedwater heater is a tube-in-shell heat exchanger in which vapor extracted from the turbine passes on the shell side and condenses, releasing its heat of vaporization to the compressed liquid stream.  The condensate is then returned to the compressed liquid stream at a point in the cycle where the pressure is lower. Superheat also decreases cycle efficiency because of the lower average heat-addition temperature. www.powerfromthesun.net /chapter12/Chapter12new.htm   (3693 words)

Efficiency Since this violates the 2nd thermodynamic law, the cycle C gives the maximum efficiency. If there were the cycle C' whose efficiency is higher than eq.(22), by coupling this cycle C' with the above cycle C, the chemical reaction could take place in a direction opposite to that predicted by its own affinity, and as a result, the total free energy in the sources increased spontaneously. From eqs.(19) and (20), the efficiency of the cycle C is given by chaos.c.u-tokyo.ac.jp /~shibata/Works/ChemicalEngine/node5.html   (316 words)

EFFICIENCY OF INTERNAL COMBUSTION ENGINES Comparing the expected efficiency for Otto Cycle engine, calculated as an exclusive function of the compression ratio, with efficiency measured in engines using the present technology, one can notice a large difference, demonstrating the inadequacy of the model used in analyzing the cycle, based exclusively on the Energy Conservation Principle. The possible refinement, at first sight, would stem from considering the irreversibility of real transformations undergone by the fuel mixture (Second Law of Thermodynamics). Otto Cycle engines efficiency evolution rate, observed and ajusted values. ecen.com /content/eee7/motoref.htm   (996 words)

Thermodynamic working fluids for Stirling-cycle, reciprocating thermal machines - Patent 4413475 A Stirling-cycle engine is a machine which operates on a closed regenerative thermodynamic cycle, with periodic compression and expansion of a gaseous working fluid at different temperature levels, and where the flow is controlled by volume changes in such a way as to produce a net conversion of heat to work, or vice versa. New thermodynamic working fluids with primary application to Stirling-cycle, reciprocating, thermal machines are disclosed which possess a greater dynamic heat transfer coefficient than either hydrogen or helium and which are both chemically inert and easily liquefied. A reversible process for a thermodynamic system is an ideal process, which once having taken place, can be reversed without causing a change in either the system or its surroundings. www.freepatentsonline.com /4413475.html   (4524 words)

Reversible process - Wikipedia, the free encyclopedia Reversible processes define the boundaries of how efficient heat engines can be in thermodynamics and engineering: a reversible process is one where no heat is lost from the system as "waste", and the machine is thus as efficient as it can possibly be (see Carnot cycle). In thermodynamics, a reversible process (or reversible cycle if the process is cyclic) is a process that can be "reversed" by means of infinitesimal changes in some property of the system (Sears and Salinger, 1986). A reversible process changes the state of a system in such a way that the net change in the combined entropy of the system and its surroundings is zero. en.wikipedia.org /wiki/Thermodynamic_reversibility   (350 words)

Rankine - Wikipedia, the free encyclopedia The Rankine cycle is an idealised thermodynamic cycle for a steam engine, i.e. Rankine is a thermodynamic temperature scale named after the Scottish engineer and physicist William John Macquorn Rankine, who proposed it in 1859. Like Kelvin, Rankine zero is absolute zero, but Fahrenheit degrees are used. en.wikipedia.org /wiki/Rankine   (178 words)

Thermal Physics [encyclopedia] Such engines operate on "thermodynamic cycles", or steps of thermodynamic processes that operate in a circular fashion. However, the Otto cycle engine is limited on the level of compression it can obtain, since at high compressions the temperatures and pressures will cause the fuel-air mixture to ignite spontaneously before the piston reaches the top of its travel. It has the same general four-stroke operational cycle as the Otto cycle engine, but uses a fuel injection system to spurt fuel directly into the cylinder at the end of the compression stroke, permitting higher compression ratios. kosmoi.com /Science/Physics/Thermodynamics   (178 words)

Internal Combustion Engines Due to the difference in the thermodynamic cycle that is used to burn the used fuel, a certain fuel was selected to suit the process. The first engine is based on a thermodynamic cycle called Diesel cycle, while the second is based on a cycle called Otto cycle. Otto cycle is the typical cycle for most of the cars internal combustion engines, that work using gasoline as a fuel. biotsavart.tripod.com /ice.htm   (2224 words)

Heat Exchanger - Cryogenic Automotive Propulsion The thermodynamic and economic performance of the adiabatic and isothermal modes of the open Rankine cycle are shown in Table 1. There are many thermodynamic cycles available for utilizing the thermal potential of liquid nitrogen. The temperature-entropy diagram for the open Rankine cycle, operated at critical pressure, is shown in Fig. www.aa.washington.edu /aerp/CRYOCAR/HeatExchanger/Propulsion.htm   (1149 words)

Stirling engine - Wikipedia, the free encyclopedia The thermodynamic efficiency is higher than steam engines (or even some modern internal combustion and Diesel engines). This regenerator contributes to the efficiency of the Stirling cycle. The ideal Stirling engine cycle has the same theoretical efficiency as a Carnot heat engine for the same input and output temperatures. en.wikipedia.org /wiki/Stirling_engine   (2154 words)

Carnot Cycle Carnot cycle is a four stage reversible sequence consisting of... The Carnot heat engine uses a particular thermodynamic cycle studied by Nicolas Léonard Sadi Carnot in the 1820s and expanded... A 19th-century French scientist named Nicolas Carnot conceived a thermodynamic cycle... www.piedmontbike.com /carnot-cycle.html   (198 words)

The Carnot Cycle This conception was proved with his thermodynamic cycle (thermodynamic processes that after numerous stages return a system to its initial state) known as the Carnot cycle, which is the basis cycle of all heat engines. Carnot also believed that the efficiency of a heat engine depended on the difference between the highest and lowest temperature reached in one cycle. This idea is also presented in the second law of thermodynamics stating that there is a limit, less than a hundred percent, in the efficiency of engines. www.massengineers.com /Documents/carnot_cycle.htm   (405 words)

Cooling Systems The use of an efficient counterflow heat exchanger, instead of a regenerative heat exchanger as required by Stirling cycle coolers and pulse tube coolers, enables reverse Brayton cycle coolers to achieve extraordinary thermodynamic efficiency in the 4 to 10 Kelvin temperature range. It is the high thermodynamic efficiency of the turboBrayton cooler, along with its very small mass and size, that make this cooler technology so appealing for space missions with detectors and other hardware operating at or below 10 Kelvin. The cooler consists of three major components, a compressor, a counterflow heat exchanger and a turboalternator (expander). lheawww.gsfc.nasa.gov /users/jleaman/cooling.html   (922 words)

The Carnot cycle Clearly the entropy of the thermodynamic system consisting of the gas which goes through the Carnot cycle does not change through one cycle because S is a state function. Next: The Stirling engine Up: Efficiency of reversible cyclic Previous: Efficiency of reversible cyclic The most efficient such engine possible is described by the Carnot cycle, named after the French engineer Sadi Carnot who invented it. www.pha.jhu.edu /~broholm/l38/node6.html   (218 words)

Open Directory - Science: Technology: Energy: Devices: Internal Combustion Engines Kruse Limited Temperature Cycle - Describes an innovative thermodynamic engine cycle which limits peak combustion temperature in direct injection petrol, gasoline and diesel engines. Addresses operation modes, thermodynamic cycle and efficiency, fuel types, support systems and parts. Carnot Cycle - Explains the basics of the Carnot cycle. dmoz.org /Science/Technology/Energy/Devices/Internal_Combustion_Engines   (297 words)

Talk:Four-stroke cycle - Wikipedia, the free encyclopedia The Otto cycle is an idealized thermodynamic model of the processes taking place in a gasoline, spark-ignited engine; the title "four-stroke cycle" should be restricted to a page describing the details of operation of a real four-stroke piston engine (e.g. The generally accepted definition of the Otto cycle (which is an idealized cycle) is based on the thermodynamic cycle - isentropic compression, constant-volume heating, isentropic expansion, constant-volume heat rejection. The "four-stroke cycle" describes a particular operating concept for an internal combustion reciprocating piston engine; it is not a synonym for the Otto cycle (despite the fact that Otto's first engine was indeed a four-stroke). en.wikipedia.org /wiki/Talk:Four-stroke_cycle   (1681 words)

Rankine cycle - Wikipedia, the free encyclopedia Like other thermodynamic cycles, the maximum efficiency of the Rankine cycle is given by calculating the maximum efficiency of the Carnot cycle. The regenerative Rankine cycle is so named because after emerging from the condenser (possibly as a subcooled liquid) the working fluid is heated by steam tapped from the hot portion of the cycle. Rankine cycles describe the operation of steam heat engines commonly found in power generation plants. en.wikipedia.org /wiki/Rankine_cycle   (573 words)

Carnot heat engine - Wikipedia, the free encyclopedia The Carnot cycle is a particular thermodynamic cycle studied by Nicolas Léonard Sadi Carnot in the 1820s and expanded upon by Benoit Paul Émile Clapeyron in the 1830s and 40s. For a clockwise cycle, the area under the upper portion will be the thermal energy absorbed during the cycle, while the area under the lower portion will be the thermal energy removed during the cycle. The area inside the cycle will then be the difference between the two, but since the internal energy of the system must have returned to its initial value, this difference must be the amount of work done by the system over the cycle. en.wikipedia.org /wiki/Carnot_cycle   (1254 words)

Carnot heat engine -- Facts, Info, and Encyclopedia article The Carnot heat engine uses a particular thermodynamic cycle studied by (French physicist who founded thermodynamics (1796-1832)) Nicolas Léonard Sadi Carnot in the (The decade from 1820 to 1829) 1820s. Needless to say, for Carnot cycle or its equivalent, the TH average is the highest temperature available and TC average is the lowest temperature available. It can also be shown that for the Carnot cycle q www.absoluteastronomy.com /encyclopedia/c/ca/carnot_heat_engine.htm   (620 words)

United States Patent Application: 0040088993 First the efficiency of the thermodynamic cycle is increased by the lower inlet temperature of the inlet gas. An organic rankine cycle system is combined with a vapor compression cycle system with the turbine generator of the organic rankine cycle generating the power necessary to operate the motor of the refrigerant compressor. In another embodiment, an organic rankine cycle system is applied to an internal combustion engine to cool the fluids thereof, and the turbo charged air is cooled first by the organic rankine cycle system and then by an air conditioner prior to passing into the intake of the engine. appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20040088993".PGNR.&OS=DN/20040088993&RS=DN/20040088993   (5600 words)

Thermodynamic Power Cycles Rankine cycle plants have a long life span, and all parts of the system are reliable and require relatively little maintenance. There are four power cycles that are generally used in the generation of electricity; the Rankine cycle, the Brayton cycle, the Otto cycle, and the Diesel cycle. The two cycles are similar in theory, with one major difference; the Otto cycle is a spark-ignition cycle, whereas the Diesel cycle is a compression ignition cycle. www.me.gatech.edu /energy/brett/four.htm   (1990 words)

Combined cycle - Wikipedia, the free encyclopedia In the combined cycle plant the thermodynamic working cycle is operated between the high firing temperature and the ambient temperature at which low temperature waste heat can be disposed. In a combined cycle power plant, or combined cycle gas turbine (CCGT) plant, a gas turbine generator is combined with a steam turbine generator with the objective to increase the efficiency of electricity generation. Typical combined cycle plants are powered by natural gas, although other sources of fuel can be used such as fuel oil or synthesis gas. en.wikipedia.org /wiki/Combined_cycle   (727 words)

Rankine cycle - Wikipedia, the free encyclopedia Like other thermodynamic cycles, the maximum efficiency of the Rankine cycle is given by calculating the maximum efficiency of the Carnot cycle. The fifth equation defines the thermodynamic efficiency of the cycle as the ratio of net power output to heat input. This increases the [[]] of heat addition which in turn increases the thermodynamic efficiency of the cycle. en.wikipedia.org /wiki/Rankine_cycle   (567 words)

General information Stirling : The Stirling thermodynamic cycle The Stirling cycle is a closed cycle, which means that the cryogenerator cooling gasses never come into contact with the substance (gas or liquid) being cooled. The cycle is remarkable because it enables the cryogenerator to produce extremely low temperatures (to -250ºC), and allows virtually all gasses and liquids to be cooled. The Stirling cycle involves alternately compressing and expanding a fixed quantity of a nearly perfect gas (also known as ideal gas) in a closed cycle. www.stirling.nl /sc/sc3.html   (508 words)

Rankine Cycle The Rankine cycle is a thermodynamic cycle used to generate electricity in many power stations, and is the real-world approach to the Carnot cycle. The Carnot Cycle has been described as being the most efficient thermal cycle possible, wherein there is no heat losses, and consisting of four reversible processes, two isothermal and two adiabatic. A turbine operates on the principal of the Brayton Cycle, which is defined as a constant pressure cycle, with four basic operations which it accomplishes simultaneously and continuously for an uninterrupted flow of power. www.cogeneration.net /Rankine_Cycle.htm   (762 words)

1903 Engine Thermodynamic Cycle - Otto Cycle During the cycle, work is done on the gas by the piston between stages 2 and 3. The work times the rate of the cycle (cycles per second) is equal to the power produced by the engine. We have broken the Otto cycle into six numbered stages based on the mechanical operation of the engine. wright.nasa.gov /airplane/otto.html   (842 words)

Thermodynamic Power Cycles The two cycles are similar in theory, with one major difference; the Otto cycle is a spark-ignition cycle, whereas the Diesel cycle is a compression ignition cycle. There are four power cycles that are generally used in the generation of electricity; the Rankine cycle, the Brayton cycle, the Otto cycle, and the Diesel cycle. The Brayton cycle is the power cycle used for gas turbines, often used in peaking applications. www.me.gatech.edu /energy/brett/four.htm   (1990 words)

The Internal Combustion Engine The advantages of the Otto cycle are fairly good thermodynamic efficiency (conversion of the heat energy released when the fuel burns into mechanical work), an excellent power-to-weight ratio and reliability due to relatively simple operation. Unfortunately, in the Otto cycle engine, the expansion ratio is the same as the compression ratio, that is, the ratio by which the charge is compressed before being ignited by the spark. In an Otto cycle engine, the fuel/air "charge" is drawn into the cylinder during the downstroke and then locked in by the intake valve closing near "bottom-dead-center". home.earthlink.net /~graham1/MyToyotaPrius/Understanding/InternalCombustion.htm   (3426 words)

Brayton cycle - Wikipedia, the free encyclopedia Like other internal combustion power cycles it is an open system, though for thermodynamic analysis it is a convenient fiction to assume that the exhaust gases are reused in the intake, enabling analysis as a closed system. The Brayton cycle is a cyclic process generally associated with the gas turbine. A Brayton engine also forms half of the combined cycle system, which combines with a rankine engine to further increase overall efficiency. en.wikipedia.org /wiki/Brayton_cycle   (573 words)

Technology The ideal Stirling cycle has the same efficiency as the famous Carnot cycle which is used to measure the performance of all thermodynamic cycles. The commercial applications of the modified Stirling cycle are based upon updated versions of secret military hardware first delivered to the military by the author in 1963 and over the years since that time. The actual refrigerator hardware design, as differentiated from cycle analysis, is a combination of engineering and intuitive modifications based upon actual test performance. www.cryomiteinc.com /page2.html   (573 words)

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