MECH 213 - 8.27.2007

MECH 213 - 8.27.2007 - Isothermal – Constant Temperature...

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MECH 213 – August 27, 2007 System – equivalent of a free body diagram; something that is being analyzed for mass and energy Isolated system – no mass or energy crossing the boundary Closed System – no mass crosses the system boundary Open System – region with a single or multiple points where the boundary is crossed (eg. Pipe) Property – any characteristic measure of a system Extensive and Intensive Thermodynamic State – a listing of the thermodynamic properties State Postulate – For a simple compressible system, two independent intensive properties define the state Equilibrium – pressures (typically) are balanced Thermal Equilibrium – temperature is balanced Chemical Equilibrium – not all reactions complete but remain balanced Process – Systemic change from one equilibrium state to another Path – Graphical Representation of series of states in a process 2 3 1 Thermodynamic Ideal Gas Law (derived from Chemistry Ideal Gas Law) pV = NRT p(V/m) = (N/m)R u T pv = (R u /M)T pv = RT where M is the Molar Mass and R is the gas constant for gas

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Unformatted text preview: Isothermal – Constant Temperature Isobaric – Constant Pressure Isochoric – Constant Volume Isentropic – Constant Entropy Process Ideal Gas Polytropic Process (Many Properties remain constant) – pv n = constant (when n=0, isobaric; when n=1, isothermal; n = k, isentropic; n ∞, isochoric) Piston system of gas under pressure and cooled in an ice bath n=0; constant p n=1, constant T n=k, constant s n ∞, constant v Steady-flow – the rate of flow-in equals the flow-out and does not change with time Uniform Flow – the velocity is constant throughout the system Temperature Scales Degrees signify a relative scale Zeroth Law of Thermodynamics – transitive property of temperatures Weight = mg = ρ(Adz)g ΣF = 0 pA – (p + dp)A +pgAdz = 0-dp +pgdz = 0 dp/dz = pg (pressure increases with depth) 1 atm (14.7psia/ 101.3kPa absolute zero Vacuum Pressure Gauge Pressure Absolute Pressure P abs = P atm – P vac...
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This note was uploaded on 04/07/2008 for the course MECH 213 taught by Professor Knisley during the Fall '08 term at Bucknell.

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MECH 213 - 8.27.2007 - Isothermal – Constant Temperature...

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