Thermodynamics Chapter 5 Review Notes

# Thermodynamics Chapter 5 Review Notes - Chapter 5 Review...

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5.1 Conservation of mass - For a closed system: the mass must remain constant - For a Control Volume – mass can enter and leave the system so we must keep track of how much mass is entering and leaving the system Mass and Volume Flow Rates Mass Flow rate – the amount of mass flowing through a cross section per unit time. c n dA V m ρ δ = = = c c A A c n dA V m m *Note: is used for quantities with inexact differentials, i.e. they are path functions and d is used to denote exact differentials. Average Velocity – In a pipe, you never have constant velocity so you use the average velocity. c A n c avg A d V A V c 1 The Mass Flow rate becomes: c avg A V m = Volume Flow Rate – the volume of a fluid flowing across a cross sectional area. c avg A V V = Relation between mass flow rate and volume flow rate: v V V m = = Conservation of Mass Principle Conservation of mass: for a control volume, the net mass transfer to or from a control volume during a time interval, is equal to the net change in the total mass in the control volume during the time interval. dt dm m m cv out in = - These equations are know as mass balance and are applicable to any control volume undergoing any kind of process. Rate of change of mass in a control volume: = cv cv dV dt d dt dm - this equals 0 for a closed system Mass Balance for a Steady Flow process - during steady flow, the mass in the control volume remains constant Steady Flow: = out in m m m m m = -

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## This note was uploaded on 04/09/2008 for the course MEE 350 taught by Professor Kostic during the Spring '08 term at Northern Illinois University.

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Thermodynamics Chapter 5 Review Notes - Chapter 5 Review...

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