Point Function And Path Function In Thermodynamics Pdf
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Remember me. Point and Path Function - Thermodynamics:.
In the thermodynamics of equilibrium , a state function , function of state , or point function is a function defined for a system relating several state variables or state quantities that depends only on the current equilibrium thermodynamic state of the system  e. A state function describes the equilibrium state of a system, thus also describing the type of system. For example, a state function could describe an atom or molecule in a gaseous, liquid, or solid form; a heterogeneous or homogeneous mixture ; and the amounts of energy required to create such systems or change them into a different equilibrium state. Internal energy , enthalpy , and entropy are examples of state quantities because they quantitatively describe an equilibrium state of a thermodynamic system , regardless of how the system arrived in that state.
State vs. Path Functions
Path Function and Point Function. Path function and Point function are introduced to identify the variables of thermodynamics. Heat is energy transferred from one system to another solely by reason of a temperature difference between the systems. Heat exists only as it crosses the boundary of a system and the direction of heat transfer is from higher temperature to lower temperature.
For thermodynamics sign convention, heat transferred to a system is positive; Heat transferred from a system is negative. Unit of heat is the amount of heat required to cause a unit rise in temperature of a unit mass of water at atmospheric pressure. Fourier's law:. If a bar of length L was put between a hot object T H and a cold object T L , the heat transfer rate is:.
Convection: Heat transfer between a solid surface and an adjacent gas or liquid. It is the combination of conduction and flow motion. Heat transferred from a solid surface to a liquid adjacent is conduction. And then heat is brought away by the flow motion.
The atmospheric air motion is a case of convection. In winter, heat conducted from deep ground to the surface by conduction. The motion of air brings the heat from the ground surface to the high air. Radiation: The energy emitted by matter in the form of electromagnetic waves as a result of the changes in the electronic configurations of the atoms or molecules.
Solar energy applications mainly use radiation energy from the Sun. The three modes of heat transfer always exist simultaneously. For example, the heat transfer associated with double pane windows are:. Dot product means the distance along the force's direction.
For example, if a car runs at a flat road, its weight does zero work because the weight and the moving distance have a 90 o angle. Like heat, Work is an energy interaction between a system and its surroundings and associated with a process. In thermodynamics sign convection, work transferred out of a system is positive with respect to that system. Work transferred in is negative. Expansion and Compression Work.
Multimedia Engineering Thermodynamics. Heat and Work. Case Intro. Case Solution. Pure Substances. First Law. Energy Analysis. Second Law. Exergy Analysis. Gas Power Cyc. Brayton Cycle. Rankine Cycle. Basic Math.
Thermo Tables. Path function: Their magnitudes depend on the path followed during a process as well as the end states. Work W , heat Q are path functions. All properties are point functions. Heat Transfer Direction. Conduction: Heat transferred between two bodies in direct contact. Double Pane Window. For example, the heat transfer associated with double pane windows are: Conduction: Hotter cooler air outside each pane causes conduction through solid glass.
Convection: Air between the panes carries heat from hotter pane to cooler pane. Radiation: Sunlight radiation passes through glass to be absorbed on other side. Please view heat transfer books for details of modes of heat transfer. Definition of Work. Work is the energy transfer associated with a force acting through a distance. Units of work is the same as the units of heat.
A system without electrical, magnetic, gravitational motion and surface tension effects is called a simple compressible system. Only two properties are needed to determine a state of a simple compressible system. Considering the gas enclosed in a piston-cylinder device with a cross-sectional area of the piston A.
Let the piston moving ds in a quasi-equilibrium manner. The differential area dA is equal to P dV. So the area under the process curve on a P-V diagram is equal, in magnitude, to the work done during a quasi-equilibrium expansion or compression process of a closed system.
Path Function & Point Function | Explained With Examples
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volume is a point function, whereas the work transferred (WA and WB) for the processes is different since work is a path function. It should also be noted that the.
Path Function and Point Function. Path function and Point function are introduced to identify the variables of thermodynamics. Heat is energy transferred from one system to another solely by reason of a temperature difference between the systems. Heat exists only as it crosses the boundary of a system and the direction of heat transfer is from higher temperature to lower temperature. For thermodynamics sign convention, heat transferred to a system is positive; Heat transferred from a system is negative.
Distinguishing between exact and inexact differentials has very important consequences in thermodynamics. All these quantities can be used to specify the state of a system.