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Global Temperature Anomaly
Temperature
Temperature
is a physical quantity expressing hot and cold. Temperature
Temperature
is measured with a thermometer, historically calibrated in various temperature scales and units of measurement. The most commonly used scales are the Celsius
Celsius
scale, denoted in °C (informally, degrees centigrade), the Fahrenheit scale
Fahrenheit scale
(°F), and the Kelvin
Kelvin
scale. The kelvin (K) is the unit of temperature in the International System of Units (SI), in which temperature is one of the seven fundamental base quantities. The coldest theoretical temperature is absolute zero, at which the thermal motion of all fundamental particles in matter reaches a minimum. Although classically described as motionless, particles still possess a finite zero-point energy in the quantum mechanical description
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Temperature (other)
Temperature
Temperature
is a physical property of a system that underlies the common notions of hot and cold. Closely related are:Thermodynamic temperature Color temperature Effective temperature Normal human body temperatureThe term may also refer to:Noise temperature, a measure of the noise of an electronic component. Temperature
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Thermodynamic Cycle
A thermodynamic cycle consists of a linked sequence of thermodynamic processes that involve transfer of heat and work into and out of the system, while varying pressure, temperature, and other state variables within the system, and that eventually returns the system to its initial state.[1] In the process of passing through a cycle, the working fluid (system) may convert heat from a warm source into useful work, and dispose of the remaining heat to a cold sink, thereby acting as a heat engine. Conversely, the cycle may be reversed and use work to move heat from a cold source and transfer it to a warm sink thereby acting as a heat pump. At every point in the cycle, the system is in thermodynamic equilibrium, so the cycle is reversible (its entropy change is zero, as entropy is a state function). During a closed cycle, the system returns to its original thermodynamic state of temperature and pressure. Process quantities (or path quantities), such as heat and work are process dependent
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Isothermal Process
An isothermal process is a change of a system, in which the temperature remains constant: ΔT = 0. This typically occurs when a system is in contact with an outside thermal reservoir (heat bath), and the change will occur slowly enough to allow the system to continually adjust to the temperature of the reservoir through heat exchange. In contrast, an adiabatic process is where a system exchanges no heat with its surroundings (Q = 0)
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Adiabatic Process
In thermodynamics, an adiabatic process is one that occurs without transfer of heat or matter between a thermodynamic system and its surroundings
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Isentropic Process
In thermodynamics, an isentropic process is an idealized thermodynamic process that is both adiabatic and reversible.[1][2][3][4][5][6] The work transfers of the system are frictionless, and there is no transfer of heat or matter. Such an idealized process is useful in engineering as a model of and basis of comparison for real processes.[7] The word 'isentropic' is occasionally, though not customarily, interpreted in another way, reading it as if its meaning were deducible from its etymology. This is contrary to its original and customarily used definition
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Isenthalpic Process
An isenthalpic process or isoenthalpic process is a process that proceeds without any change in enthalpy, H; or specific enthalpy, h.[1]Contents1 Overview 2 See also 3 References3.1 NotesOverview[edit] In a steady-state, steady-flow process, significant changes in pressure and temperature can occur to the fluid and yet the process will be isenthalpic if there is no transfer of heat to or from the surroundings, no work done on or by the surroundings, and no change in the kinetic energy of the fluid.[2] (If a steady-state, steady-flow process is analysed using a control volume everything outside the control volume is considered to be the surroundings.[3]) The throttling process is a good example of an isenthalpic process. Consider the lifting of a relief valve or safety valve on a pressure vessel
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Quasistatic Process
In thermodynamics, a quasi-static process is a thermodynamic process that happens slowly enough for the system to remain in internal equilibrium. An example of this is quasi-static compression, where the volume of a system changes at a rate slow enough to allow the pressure to remain uniform and constant throughout the system.[1] Any reversible process is necessarily a quasi-static one. However, quasi-static processes involving entropy production are irreversible. An example of a quasi-static process that is not reversible is a compression against a system with a piston subject to friction—although the system is always in thermal equilibrium, the friction ensures the generation of dissipative entropy, which directly goes against the definition of reversible
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Polytropic Process
A polytropic process is a thermodynamic process that obeys the relation: p V n = C displaystyle pV^ ,n =C where p is the pressure, V is volume, n is the polytropic index , and C is a constant
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Free Expansion
Free expansion
Free expansion
is an irreversible process in which a gas expands into an insulated evacuated chamber. It is also called Joule expansion. Real gases experience a temperature change during free expansion. For an ideal gas, the temperature doesn't change, and the conditions before and after adiabatic free expansion satisfy ( P i ) ( V i ) = ( P f ) ( V f ) displaystyle (P_ i )(V_ i )=(P_ f )(V_ f ) , where p is the pressure, V is the volume, and i and f refer to the initial and final states. Since the gas expands, Vf > Vi , which implies that the pressure does drop (Pf < Pi). During free expansion, no work is done by the gas
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Reversible Process (thermodynamics)
In thermodynamics, a reversible process is a process whose direction can be "reversed" by inducing infinitesimal changes to some property of the system via its surroundings, with no increase in entropy.[1] Throughout the entire reversible process, the system is in thermodynamic equilibrium with its surroundings. Since it would take an infinite amount of time for the reversible process to finish, perfectly reversible processes are impossible. However, if the system undergoing the changes responds much faster than the applied change, the deviation from reversibility may be negligible. In a reversible cycle, a cyclical reversible process, the system and its surroundings will be returned to their original states if one half cycle is followed by the other half cycle.[2] Thermodynamic processes can be carried out in one of two ways: reversibly or irreversibly. Reversibility means the reaction operates continuously at equilibrium
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Irreversible Process
In science, a process that is not reversible is called irreversible. This concept arises frequently in thermodynamics. In thermodynamics, a change in the thermodynamic state of a system and all of its surroundings cannot be precisely restored to its initial state by infinitesimal changes in some property of the system without expenditure of energy. A system that undergoes an irreversible process may still be capable of returning to its initial state. However, the impossibility occurs in restoring the environment to its own initial conditions. An irreversible process increases the entropy of the universe. Because entropy is a state function, the change in entropy of the system is the same, whether the process is reversible or irreversible
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Endoreversible Thermodynamics
Endoreversible thermodynamics
Endoreversible thermodynamics
is a subset of irreversible thermodynamics aimed at making more realistic assumptions about heat transfer than are typically made in reversible thermodynamics
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Heat Engine
In thermodynamics, a heat engine is a system that converts heat or thermal energy—and chemical energy—to mechanical energy, which can then be used to do mechanical work.[1][2] It does this by bringing a working substance from a higher state temperature to a lower state temperature. A heat source generates thermal energy that brings the working substance to the high temperature state. The working substance generates work in the working body of the engine while transferring heat to the colder sink until it reaches a low temperature state. During this process some of the thermal energy is converted into work by exploiting the properties of the working substance. The working substance can be any system with a non-zero heat capacity, but it usually is a gas or liquid. During this process, a lot of heat is lost to the surroundings and so cannot be converted to work. In general an engine converts energy to mechanical work
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Isobaric Process
An isobaric process is a thermodynamic process in which the pressure stays constant: ΔP = 0. The heat transferred to the system does work, but also changes the internal energy of the system. This article uses the chemistry sign convention for work, where positive work is work done on the system. Using this convention, by the first law of thermodynamics,The yellow area represents the work done Q = Δ U − W displaystyle Q=Delta U-W, where W is work, U is internal energy, and Q is heat.[1] Pressure-volume work by the closed system is defined as: W = − ∫ p d V displaystyle W=-int !p,dV, where Δ means change over the whole process, whereas d denotes a differential
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Heat Pump And Refrigeration Cycle
Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pumps and refrigerators. A heat pump is a machine or device that moves heat from one location (the "source") at a lower temperature to another location (the "sink" or "heat sink") at a higher temperature using mechanical work or a high-temperature heat source.[1] Thus a heat pump may be thought of as a "heater" if the objective is to warm the heat sink (as when warming the inside of a home on a cold day), or a "refrigerator" if the objective is to cool the heat source (as in the normal operation of a freezer)
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