basic concepts of thermodynamics – the science of energy · copyright drjj, aserg, fsg, uitm,...

Copyright DRJJ, ASERG, FSG, UiTM, 2004 1

Thermodynamics Lecture SeriesThermodynamics Lecture SeriesCapturing the LingoCapturing the Lingo

Assoc. Prof. Dr. Jaafar Jantan aka DR. JJApplied Science Education Research

Applied Science, UiTM, Shah Alam

Voice: 019Voice: 019--455455--16211621 email: email: [email protected]@hotmail.com; ; [email protected]@salam.uitm.edu.myWebsite: http://www3.uitm.edu.my/staff/drjj/drjj1.htmlWebsite: http://www3.uitm.edu.my/staff/drjj/drjj1.html

JJourneyourney towards

EEnrichmentnrichment and

BBalancealance utilizing

AArts and Sciencesrts and Sciences i n

TTeaching & Learningeaching & Learning

Deep Impact Deep Impact Mission: Flyby Mission: Flyby camera capturing the camera capturing the image when image when impactorimpactor spacecraft spacecraft collides with collides with TempelTempel1 on July 31 on July 3rdrd..

8/10/2005


You do not learn much just sitting in classes listening to teachers, memorizing prepackaged assignments, and spitting out answers. You must talk about what you are learning, write reflectively about it, relate it to past experiences, and apply it to your daily lives. You must make what you learn part of yourselves.”

-Source:"Implementing the Seven Principles: Technology as Lever" by Arthur W. Chickering and Stephen C. Ehrmann

“Learning is not a spectator sport.

“Education is the kindling of a flame, not the filling of a vessel” - Socrates.

8/10/2005


Objectives/Intended Learning Outcome:Objectives/Intended Learning Outcome:

LearningLearning

At the end of this session, participants should be able to:

1. State, discuss and apply the terminologies used in thermodynamics to daily life.

2. State and identify origins and transformations of the many different forms of energy

3. State and discuss the characteristics and description of changes from and to a system

4. State and discuss the zeroth law of thermo.

CHAPTER

1

Basic Concepts of Thermodynamics –

The science of Energy

FIGURE 1–5Some application areas of thermodynamics.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

1-1

Steam Power PlantSteam Power Plant


FIGURE 1–13System, surroundings, and boundary.


1-3

FIGURE 1–14Mass cannot cross the boundaries of a closed system, but energy can.


1-4

SystemsSystems

A rigid tank

WinWout

QinQout

Dynamic Energies cross in and out

Dynamic Energies cross in and out

NO VOLUME CHANGEVinitial = VfinalV = constant

NO VOLUME CHANGEVinitial = VfinalV = constant

SystemsSystems

An isolated system

NO mass transfer min = mout = 0

NO mass transfer min = mout = 0

NO dynamic energy transferEin = Eout = 0

NO dynamic energy transferEin = Eout = 0

FIGURE 1–17A control volume may involve fixed, moving, real, and imaginary boundaries.


1-5

Open system devicesOpen system devices

Heat ExchangerThrottle


PropertiesProperties:•Temperature•Pressure•Volume•Internal energy•Entropy

Properties:•Temperature•Pressure•Volume•Internal energy•Entropy

SystemSystem

The system can be either open or The system can be either open or closed. The concept of a propertyclosed. The concept of a property

still applies.still applies.

First Law of ThermodynamicsFirst Law of Thermodynamics

System expands

Movable boundary position gone up

A change has taken place.

SystemSystem

Classes of properties

• Extensive– MASS, m– VOLUME, V– ENERGY, E

ADDITIVE OVER THE SYSTEM.

•• ExtensiveExtensive–– MASS, mMASS, m–– VOLUME, VVOLUME, V–– ENERGY, EENERGY, E

ADDITIVEADDITIVE OVER OVER THE SYSTEMTHE SYSTEM..

• Intensive– TEMPERATURE, T– PRESSURE, P– DENSITY– Specific properties

NOT ADDITIVE OVER THE SYSTEM.

•• IntensiveIntensive–– TEMPERATURE, TTEMPERATURE, T–– PRESSURE, PPRESSURE, P–– DENSITYDENSITY–– Specific propertiesSpecific properties

NOTNOT ADDITIVEADDITIVE OVER OVER THE SYSTEMTHE SYSTEM..

Classes of properties

Extensive: Total :

V = V1 + V2 + V3

E = E1 + E2 + E3

m = m1 + m2 + m3

Extensive: Total :

V = V1 + V2 + V3

E = E1 + E2 + E3

m = m1 + m2 + m3

Box with 3 sections after equilibriumBox with 3 sections after equilibrium

Intensive: not size independent

ν = ν1 = ν2 = ν3 = V/m

e = e1 = e2 = e3 = E/m

T, P

Intensive: not size independent

ν = ν1 = ν2 = ν3 = V/m

e = e1 = e2 = e3 = E/m

T, P

States

• State– A set of properties describing the

condition of a system • A change in any property, changes the

state of that system

•• StateState–– A set of properties describing the A set of properties describing the

condition of a system condition of a system •• A change in any property, changes the A change in any property, changes the

state of that systemstate of that system

States

• Equilibrium– A state of balance– Thermal – temperature same at all points

of system– Mechanical – pressure same at all points

of system at all time– Phase – mass of each phase about the

same– Chemical – chemical reaction stop

•• EquilibriumEquilibrium–– A state of balanceA state of balance–– Thermal Thermal –– temperature same at all points temperature same at all points

of systemof system–– Mechanical Mechanical –– pressure same at all points pressure same at all points

of system at all timeof system at all time–– Phase Phase –– mass of each phase about the mass of each phase about the

samesame–– Chemical Chemical –– chemical reaction stopchemical reaction stop


States

• State postulate– Must have 2 independent intensive

properties to specify a state: • Pressure & specificinternal energy• Pressure & specific volume• Temperature & specific enthalpy

•• State postulateState postulate–– Must have 2 independent intensive Must have 2 independent intensive

properties to specify a state: properties to specify a state: •• Pressure Pressure & specific& specificinternal energyinternal energy•• Pressure & specific volumePressure & specific volume•• Temperature & specific enthalpyTemperature & specific enthalpy

Processes and cycles

First Law of ThermodynamicsFirst Law of Thermodynamics

SystemE1, P1 , T1, V1

ToE2, P2 , T2, V2

Properties will change indicating change of

state

Mass out

Mass inWinWout

QinQout

FIGURE 1–25A process between states 1 and 2 and the process path.


1-6

FIGURE 1–28The P-V diagram of a compression process.


1-7

Thermodynamic process

State 1

State 2

p

V

T


Example: Heating water

Heat supplied by electricity or combustion.

T1 T1+dT T1+2dT T2

T1 T1+dT T1+2dT T2

….

System analysis of the slow heating process:System analysis of the slow heating process:

Energy in via electricityEnergy in via electricityor gas combustionor gas combustion

System BoundarySystem Boundary Neglect vapor loss

Twater

Theater

Assume no heatlosses from sides and bottom.

System analysis for the water under equilibrium processes:System analysis for the water under equilibrium processes:

Heating via an equilibrium processHeating via an equilibrium process

Energy InEnergy In

Twater

Theater

Reversed process of slow cooling, Reversed process of slow cooling, which is reversible for the waterwhich is reversible for the water

Energy OutEnergy Out

Twater

Theater

Processes & Equilibrium States

What is the state of the system alongthe processpath?

What is the state of the system alongthe processpath?

p

V

T

S1

S2

Process Path

Thermodynamic process

T

State 1

State 2

Process 1 p

V Process 2

Thermodynamic cycles

P1

P2

State 1State 2

Process Path I

Process Path II


Example: A steam power cycle.Example: A steam power cycle.

SteamTurbine

Mechanical Energyto Generator

Heat Exchanger

Cooling Water

Pump

Fuel

Air

CombustionProducts

System Boundaryfor ThermodynamicAnalysis

System Boundaryfor ThermodynamicAnalysis

Types of Energy

Types of Energy

• Dynamic– Heat, Q– Work, W– Energy of moving

mass, Emass

Crosses in and out of system’s boundary

•• DynamicDynamic–– Heat, QHeat, Q–– Work, WWork, W–– Energy of moving Energy of moving

mass, mass, EEmassmass

Crosses in and out of Crosses in and out of system’s boundarysystem’s boundary

• System– Internal, U– Kinetic, KE– Potential, PE

Changes occuringwithin system

•• SystemSystem–– Internal, UInternal, U–– Kinetic, KEKinetic, KE–– Potential, PEPotential, PE

Changes Changes occuringoccuringwithin systemwithin system

Types of Energy

• Internal, U– Sensible,

• Relates to temperature change– Latent

• Relates to phase change

•• Internal, UInternal, U–– Sensible, Sensible,

•• Relates to temperature changeRelates to temperature change–– LatentLatent

•• Relates to phase changeRelates to phase change

FIGURE 1–32The various forms of microscopic energies that make up sensible energy.


1-8

Types of Energy

• Kinetic– Changes with square of velocity

• KE = (mv2)/2, kJ; ke = v2/2, kJ/kg– If velocity doubles,

• KE = (m(2v)2)/2 = (4mv2)/2, kJ– If decrease by ½, then

• KE = (m(v/2)2)/2 = (mv2)/8, kJ

•• KineticKinetic–– Changes with square of velocityChanges with square of velocity

•• KE = (mvKE = (mv22)/2, kJ; )/2, kJ; keke = v= v22/2, kJ/kg/2, kJ/kg–– If velocity doubles,If velocity doubles,

•• KE = (m(2v)KE = (m(2v)22)/2 = (4mv)/2 = (4mv22)/2, kJ)/2, kJ–– If decrease by ½, then If decrease by ½, then

•• KE = (m(v/2)KE = (m(v/2)22)/2 = (mv)/2 = (mv22)/8, kJ)/8, kJ


Types of Energy

• Potential– Changes with vertical position,

• PE = mg(yf - y i) = mgh, kJ; pe = gh, kJ/kg– If position above reference point doubles,

• PE = mg(2h), kJ; pe = g2h, kJ/kg– If decrease by ½, then

• PE = mgh/2, kJ; pe = gh/2, kJ/kg

•• PotentialPotential–– Changes with vertical position,Changes with vertical position,

•• PE = PE = mg(ymg(yff -- yy ii) = ) = mghmgh, kJ; , kJ; pepe = = ghgh, kJ/kg, kJ/kg–– If position above reference point doubles,If position above reference point doubles,

•• PE = mg(2h), kJ; PE = mg(2h), kJ; pepe = g2h, kJ/kg= g2h, kJ/kg–– If decrease by ½, thenIf decrease by ½, then

•• PE = mgh/2, kJ; PE = mgh/2, kJ; pepe = gh/2, kJ/kg= gh/2, kJ/kg

APPLICATION OF THE EQUILIBRIUM PRINCIPLE

Zeroth Law of ThermodynamicsHeat, and Temperature

Temperature & heat...

Heat & temperature

Large bodyat constanttemperatureT1

Large bodyat constanttemperatureT1

Large bodyat constanttemperatureT2<T1

Large bodyat constanttemperatureT2<T1

Our sense of the direction ofOur sense of the direction ofheat flow heat flow -- from high to low temperature.from high to low temperature.

Temperature and heat are related.

For metals, highFor metals, highheat flow heat flow -- diathermaldiathermalmaterials.materials.

T1TT11

T2TT22

For nonmetals, lowFor nonmetals, lowheat flow heat flow -- insulating.insulating.

T1TT11

T2TT22

Caloric definition of temperature

TT11TT22

Isolatingboundaries

21 TT >


Bring systems into thermal contact and surroundBring systems into thermal contact and surroundwith an isolating with an isolating ---- adiabatic adiabatic ---- boundary.boundary.

Initial configuration of the closed, combined Initial configuration of the closed, combined systems with a systems with a diathermaldiathermal wallwall between the two. between the two.

TT11 TT22

Heat is observed to flow from the subsystem at the Heat is observed to flow from the subsystem at the higher temperature to that with the lower temperature. higher temperature to that with the lower temperature.

TT11 TT22

The final observed state of the total system is The final observed state of the total system is that when the temperatures are equal. Heat that when the temperatures are equal. Heat flow from subsystem 1 to subsystem 2 decreases flow from subsystem 1 to subsystem 2 decreases in time.in time.

TT1,final1,final TT2,final2,final

Zeroth Law of Thermodynamics...

Thermal equilibrium

TT11 TT22

TT1,final1,final TT2,final2,final

21 TT >Initial State:Initial State:

21 TT =Final State:Final State:

Demonstration of the Zeroth Law

Two subsystems in equilibrium with a third subsystemTwo subsystems in equilibrium with a third subsystem

Adiabatic

Diathermal

BB

DD

AA

DD

CC


Two systems in thermal Two systems in thermal equilibrium with a third equilibrium with a third

system are in thermal system are in thermal equilibrium with each other.equilibrium with each other.

The Zeroth Law FIGURE 1–41The greenhouse effect on earth.


1-11


FIGURE 1–45P versus T plots of the experimental data obtained from a constant-volume gas thermometer using four different gases at different (but low) pressures.

1-12


FIGURE 1–47Comparison of temperature scales.

1-13


FIGURE 1–51Absolute, gage, and vacuum pressures.

1-14


FIGURE 1–55The pressure is the same at all points on a horizontal plane in a given fluid regardless of geometry, provided that the points are interconnected by the same fluid.

1-15



FIGURE 1–57The basic manometer.

1-16


FIGURE 1–61Schematic for Example 1–8.

1-17


FIGURE 1–63The basic barometer.

1-18


FIGURE 1–75Some arrangements that supply a room the same amount of energy as a 300-W electric resistance heater.

1-19

FIGURE 1–39Ground-level ozone, which is the primary component of smog, forms when HC and NOx react in the presence of sunlight in hot calm days.


1-9

FIGURE 1–40Sulfuric acid and nitric acid are formed when sulfur oxides and nitric oxides react with water vapor and other chemicals high in the atmosphere in the presence of sunlight.


1-10


FIGURE 1–7The definition of the force units.


1-2

basic concepts of thermodynamics – the science of energy · copyright drjj, aserg, fsg, uitm,...

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