Thermody

• Thermodynamics


  A branch of physical sciences that treats various phenomena of energy and the related properties of matter, especially of the laws of transformation of heat into other forms of energy and vice versa
• Surroundings


  • The mass or region outside the system
• Boundary


  • The real or imaginary surface that separates the system from its surroundings. It can be either fixed or movable
• Thermodynamic System


  • The quantity of matter or certain volume in space chosen for study
• Closed System


  • A system in which there is no transfer of matter across the boundary. Has a fixed amount of mass, and no mass can enter or leave the system
• Open System


  • A system in which there is a flow of matter through the boundary
• Isolated System


  • A system in which neither mass nor energy cross the boundaries and it is not influenced by the surroundings
• State Properties


  • The physical condition of the working substance such as temperature, pressure, density, specific volume, specific gravity or relative density
• Transport Properties


  • The measurement of diffusion within the working medium resulting from molecular activity, like; viscosities, thermal conductivities, and etc.
• Intensive Properties


  • Properties which are size independent such as temperature, pressure, and density
• Extensive Properties


  • Properties which depend on the size or extent of the system
• Temperature

  An indication or degree of hotness and coldness and therefore a measure of intensity of heat
• Absolute Temperature

  The temperature measured from absolute zero
• Absolute Zero

  The temperature at which the molecules stop moving. It is equivalent to 0 K or 0 deg Rankine
• Temperature Interval

  The difference between two temperature readings from the same scale, and the change in temperature through which the body is heated
• Pressure

  The force exerted per unit area
• Absolute Pressure


  The true pressure measured above a perfect vacuum
• Gage Pressure

  The pressure measured from the level of atmospheric pressure by most pressure recording instrument like pressure gage and open-ended manometer
• Atmospheric Pressure


  The pressure obtained from barometric reading
• Density


  The mass per unit volume
• Specific Volume


  The volume per unit mass
• Specific Gravity


  The ratio of the density of a certain substance to the density of water
• Heat


  A form of energy associated with the kinetic random motion or large number of molecules
• Sensible Heat


  The heat needed to change the temperature of the body without changing its phase
• Latent Heat

  The head needed by the body to change is phase without changing its temperature
• Sublimation


  The term used to describe the process of changing solid to gas without passing the liquid state
• Deposition


  The reverse of sublimation. The process of changing gas to solid without passing the liquid state
• Entropy


  The measure of randomness of the molecules of a substance
• Enthalpy


  The heat energy transferred to a substance at a constant pressure process
• Internal Energy


  The energy stored within the body. The sum of the kinetic energies of all its constituent particles plus the sum of all the potential energies of interaction among these particles
• First Law of Thermodynamics

  Energy can neither be created nor destroyed; rather it can only be transformed from one form to another
• Second Law of Thermodynamics

  Heat cannot be transferred from cold body to a hot body without an input of work. Heat cannot be converted 100% into work
• Kelvin-Plank Statement


  It is impossible to construct a heat engine which operates in a cycle and receives a given amount of heat from a high temperature body and does an equal amount of work
• Third Law of Thermodynamics

  The total entropy of pure substances approaches zero as the absolute thermodynamic temperature approaches zero
• Zeroth Law of Thermodynamics

  When any two bodies are in thermal equilibrium with the third body, then they are in thermal equilibrium with each other
• Perfect Gas


  A theoretically ideal gas which strictly follows Boyle's Law and Charle's Law of gasses
• Thermodynamics Process


  A change in that a system undergoes from one equilibrium state to another
• Path


  The series of states through which a system passes during a process
• Reversible Process


  The process that can be reversed without leaving any trace on the surroundings. Also known as quasi-equilibrium process
• Irreversible Process


  The process that process spontaneously in one direction but the other