CHAPTER 1 Introduction to Thermodynamic

8/4/2019 CHAPTER 1 Introduction to Thermodynamic

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CHAPTER 1

BASIC CONCEPTS OFTHERMODYNAMICS

Sub chapter covered1.1 Thermodynamics and Energy1.2 Closed and Open System1.3 Properties of the System1.4 Reversible & Irreversible Process1.5 State and Equilibrium


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http://www.grc.nasa.gov/WWW/K-12/airplane/shortp.html


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1.1 Thermodynamics

Ways energy is stored within abody and how energy

transformations, which involveheat and work, may take place.


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Fundamental law of nature

Conservation of energy principle:

energy can change form but

the total amount of energy remainsconstant.

Energy cannot be created nordestroyed


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0dt

dm

ClosedSystem

OpenSystem

Mass Flow

Mass Flow

1.2 Closed and Open system

System and Surroundings

system quantity of

matter or region in spacechosen for study

surroundings mass orregion outside the system

boundary surfaceseparate systemfrom surrounding(imaginary @ real)


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Closed system does not have mass

flow across the boundary.

Only energy

Closed System

Surroundings

System Boundary

m= constant


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Open systems have mass & energy flowacross their boundaries.

Open System

( Fixed space or volume)

Surroundings Control Surface

Mass flow


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Interactions between system andsurroundings...

System

Surroundings

Work

Heat

System

Surroundings

Mass Flow

Mass

FlowPower

Heat

Closed system (controlmass) no mass can enter orleave a system Also in special case system

can consider as isolatedsystem

Open system (controlvolume) usually enclosesa device that involves massflow such as compressor,turbine or nozzle.


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Example of open system andclosed system

Closed system (Piston and Cylinder)

Open system (Gas Turbine Engine)m

Gas at pressure, p

Piston

Shaft Work Output

Combustor

Fuel Flow In

Air Flow In

Exhaust Gases Out

Compressor Work Out


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1.3 Properties of the system

Any characteristic of a system called property

Some familiar property are pressure P,

temperature T, volume V, and mass m

Properties are consider to be eitherintensiveor extensive


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Intensive propertiesthose that areindependent of the size of the system, such as

temperature, pressure and density

Extensive propertiesthose whose valuesdepend on the size or extent of the system such

as mass, volume and total energy


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1.4 Reversible &Irreversible Process

Process: system undergoes from oneequilibrium state to another.

Reversible: Process that can bereversed without leaving any trace on thesurrounding

eg: Pendulum

System and surrounding return to theirinitial state.


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Irreversible: Surrounding do somework on the system & therefore does

not return to their initial state.


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1.5 State and Equilibrium

Equilibrium: state of balance

A system in equilibrium experiences

no changes when it is isolated from itssurrounding.

Eg: thermal equilibrium, mechanical

equilibrium, chemical equilibrium.


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Path: series of state which the systempasses during the process completely.

Quasi equilibrium process:

Slow process that allows the system to

adjust internally so that the properties in

one part of the system do not change

any faster than those at other part.


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Steady: no change with time

Uniform: no change with location

Steady flow process

Steadily fluid flow processthrough a control volume.

V, m, total E content of controlvolume remain constant.

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CHAPTER 1 Introduction to Thermodynamic