mae 431 energy systems i - university at buffalo · aircraft - high velocity jet transportation -...

1

MAE 431 ENERGY SYSTEMS I

http://www.eng.buffalo.edu/Courses/mae431

ENERGY SOURCES TYPE DISADVANTAGE ADVANTAGE COAL Deep Mine Strip Mine

Heat Energy 12,000Btu/lb Chemical

Environtal Damage Occupational Danger

Cheap, Abundant

NATURAL GAS Conventional Shale Gas

Heat Energy 950 Btu/ft3

Chemical

Well sealing Water clean up Difficult in ransportation

Cheap Abundant

OIL Conventional Shale Oil

Heat Energy 18,000 Btu/lb Chemical

Very Transportable Limited Supply

Expensive Politically Sensitive

GEOTHERMAl Heat Energy Limited Supply No Fuel Cost NUCLEAR FISSION Heat Energy Radioactive waste

Capital Cost Fuel cost

FUSION Heat Energy Not Commercial Long Development (50 yr)

Fuel Cost Low Radiation Unlimited Supply

SOLAR Thermal Heat Energy 200-250 Btu/ft2 hr

Large Area Required Unavailable Periods

No Fuel Cost

BIOFUELS Heat Energy Oil replacement HYDRO Potential Limited Locations No Fuel Cost WIND Kinetic Energy

> 30 mph required Limited Locations Unavailable Periods

No Fuel Cost

SOLAR Photovoltaic Radiation Energy 200-250 Btu/ft2 hr

Large Area Required Unavailable Periods

No Fuel Cost

WAVE AND TIDE Kinetic Energy Limited Locations Capital Cost

No Fuel Cost

ELECTRICITY?

HYDROGEN?

ENERGY SYSTEMS ENERGY SOURCE TYPE ENERGY SYSTEMS COAL Deep Mine Strip Mine

Heat Energy 12,000Btu/lb

Steam Electric Heating Synfuel

NATURAL GAS Conventional Shale Gas

Heat Energy 950 Btu/ft3

Gas Turbine Electric Gas Turbine Mechanical Combined Cycle Heating

OIL Conventional Shale Oil

Heat Energy 18,000 Btu/lb

Gasoline Engine Diesel Engine Heating Aircraft Gas Turbinel

GEOTHERMAl Heat Energy Steam Electric NUCLEAR FISSION Heat Energy Steam Electric FUSION Heat Energy Steam Electric SOLAR Thermal Heat Energy

200-250 Btu/ft2hr Steam Electric

BIOFUELS Heat Energy Oil Substitute HYDRO Potential Energy Electric WIND Kinetic Energy

> 30 mph required Electric

SOLAR Photovoltaic Radiation Energy 200-250 Btu/ft2 hr

Electric

WAVE AND TIDE Kinetic Energy Electric

4

Gas Power Cycles Brayton Cycle Gas Turbine Aircraft - high velocity jet Transportation - mechanical powerStationary power - mechanical power

Otto Cycle - spark ignition engines Diesel engines

- trucks, locomotives, stationary powerCompression Systems

- Process Industry, Air toolsVapor Power Cycles

Rankine Cycle steam and nuclear plantsOrganic Cycle systems

Refrigeration CyclesVapor compression - air conditioning, refrigerationHeat PumpsReverse Brayton Cycle - air conditioning, cryogenics

Non-Reacting MixturesGas MixturesPsychrometrics

Non-Reacting MixturesGas MixturesPsychrometrics

Reacting MixturesCombustion

5

Chapter 1 ConceptsThermodynamic system, properties, state

point, process, cycle, heat and work.Thermodynamic problem solving technique.

Chapter 3 Fluid PropertiesReal gases - steam, air, refrigerants tablesIdeal gases, Equations of stateFirst Law in Closed Systems

Chapter First LawFirst Law for processes and cycles

Chapter 6 Second LawStatement and CorollariesHeat EnginesReversible engines and refrigeratorsCarnot Cycle

Chapter 7 EntropySecond Law and heat enginesThe Entropy propertyIsentropic processEntropy change calculation

Course SummaryREVIEW OF THERMODYNAMICSChapters 1-6, about 3 weeks

Chapter 4 Closed SystemsFirst Law in closed Systems

Chapter Control VolumesMass balance in Open SystemsFirst Law in Open Systems

6

Chapter 9 Gas Power CyclesBrayton (gas turbine) cycleOtto (spark ignition engine) cycleDiesel cycle

Chapter 10 Vapor Power CyclesRankine (steam power) reheat,

superheat and regeneration cycles

Chapter 11 Refrigeration CyclesVapor Compression CycleHeat PumpsReversed Brayton Cycle

Course SummaryENERGY SYSTEM TOPICSChapters 7-13, about 11 weeks

Chapter 12 Property RelationshipsUsing equations of stateMaxwell RelationsProperty Evaluation

Chapter 13 MixturesProperties of mixtures.

Chapter 15 Reacting MixturesReaction mass balances.Reacting energy balances.Combustion

Chapter 8 Exergy, AvailiabilityAvailability in Energy SystemsExergy

Chapter 14 Gas- Vapor MixturesProperties of air water vapor mixtures.Psychrometrics

8

inQ

turbinecompressorWW = outputnet

W

Aero-derivative Gas Turbine

PowerTurbine

GasGenerator

9

Furnas Hall J79-GE-8A Fighter Turbojet EngineFirst flight 1955, 17,000 built, replaced 1960Compressor (right end), Combustor (red) Turbine (left end)

10

Furnas Hall J79-GE-8A Fighter Turbojet EngineCombustor (red) and Turbine Stages

11

Gas Turbine TechnologiesThermodynamics

- process design, T, p and mass flowAerodynamics

- compressor and turbine bladesStress AnalysisVibrationBearing and Lubrication SupplyRotordynamicsManufacturing ProcessesMechanical DesignControls and instrumentation

Energy Systems are not all thermodynamics. Thermodynamics is the beginning of Energy System design – Process Design.

This Course: Thermodynamics of Energy SystemsProcess Design of Energy Systems

Gas Turbine Engineering TasksDesign RequirementsDevelopmentDesignDevelopment TestingManufactureShop TestingField TestingInstallationMaintenanceOperationRevamp

12

Thermodynamics OverviewThermodynamics

Thermodynamics is the study of the relationship between allforms of Energy beginning historically with the relationship between Heat and Work.

Laws of Thermodynamics ( fundamental observations)Mass Balance (should be a law)

Mass can not be created or destroyed and is conserved.

First Law (Energy Balance)Heat and work are equivalentProperty energy is definedEnergy can change form, can not be destroyed, and is conserved

Second LawHeat can not be converted completely to work.Property entropy defined.Ideal and actual heat engine efficiency.

13

Thermodynamics Concepts

Thermodynamic SystemPropertiesState Point ProcessCycleHeatWorkEnergy

First Law - Energy Balance lead the analysis

14

Thermodynamic

HEATWORK

MASS

Control Volume

3 Types of SYSTEMSClosedOpenUnsteady

CONCEPTSSystemPropertiesState PointProcessCycle

15

CLOSED THERMODYNAMIC SYSTEMNON FLOW SYSTEM

A mass of material. Heat and Work can

cross the system boundaries. Mass can not.

Examples:A closed tank.A piston cylinder.Internal Combustion Cylinder

WorkHeat


16

OPEN THERMODYNAMIC SYSTEMSTEADY FLOW SYSTEM

A fixed region in space. Mass, heat and work can cross the system boundaries.Examples:

turbine, compressors,boilers, heat exchangers

Mass inMass out

HeatWork


17

UNSTEADY FLOW THERMODYNAMIC SYSTEM

A variable region in space.Mass, heat and work cancross the system boundaries

Examples:A filling tank.An emptying tankPiston-Cylinder Filling

WorkHeat

Mass


18

Thermodynamic PropertiesTemperaturePressure VolumeInternal EnergyEnthalpyEntropy

vmassV ft,m

lbm/ft,kg/m/lbft/kg,m

pressureAmbient pressure Gagepressure Absolute lb/in bar, s,atmosphere kPa,

459.69FR273.15CK

32.C1.8FRK, absolute, C,F,

33

33

33

2

oo

oo

oo

oooo

×=−

−

−

+=−

+=

+=

+×=

−

VolumeV Density ρ

lumeSpecificVo v

Pressure p

eTemperatur


19

Thermodynamic Properties

smS KkJ/

FBTU/lbm C,kJ/kghmH

BTU kJ,

FBTU/lbm C,kJ/kg pressure,constant at heat specificc

dTcdh pvuh

BTU/lbm kJ/kg,

o

oo

oop

p

×=−

−

×=−

=+=

−

Entropy SEntropy Specific s

Enthalpy H

Enthalpy Specific h

BTU kJ,FBTU/lbm C,/kgm kG/jg,

olume,constant vat heat specifcc dTcdu

BTU/lb kJ/kg,

oo3v

v

−

−=

−

ergyInternalEn U

gyternalEnerSpecificIn u


20

THERMODYNAMIC STATE POINT

Properties are measured.

Equations and models are fitted to the data resulting in :

Tables of Property ValuesEquations of StateComputer property modules

Two properties define thestate point of a single phasefluid.

One property defines the state point of a multiphasefluid.

absisa property

ordinate property

(T,p,v,u,h,s)


21

THERMODYNAMIC PROCESSA thermodynamic process is an interaction between a thermodynamic system and

its surroundings which results in a change in the state point of the system

Reversible ProcessA process is reversible if the state points of all affectedthermodynamic systems, including the external systemor surroundings, are returned to their original state point values.

Examples:- movement of a frictionless pendulum- transfer of work to potential energy without loss- movement of a frictionless spring

Irreversible ProcessA process which can not be reversed bringing all the affected

thermodynamic properties back to their original values is irreversible.

Examples:

- applying brakes to a moving wheel

- mixing hot and cold water

- transfer of heat through a finite temperature difference

WorkHeat


22

THERMODYNAMIC CYCLE

A thermodynamic system undergoesa cycle when the system is subjected to a seriesof processes and all of the state point properties of the system are returned to their initial values.

p

vinitial point

dependent.path is that ederiviativ a al,differentiinexact an is δ

WQ

LawFirst

WW

QQ

cycleprocessnetcycle

cycleprocess

netcycle

∫∫

∑

∑

δ=δ

=

=


23

1. Problem StatementCarbon dioxide is contained in a cylinder

with a piston. The carbon dioxide is compressedwith heat removal from T1,p1 to T2,p2. The gasis then heated from T2, p2 to T3, p3 at constant volume and then expanded without heat transfer to the original state point.

2. Schematic

3. Select Thermodynamic Systemopen - closed - control volume

a closed thermodynamic systemcomposed to the mass of carbondioxide in the cylinder

4. Property Diagramstate points - processes - cycle

T1,p1

T3,p3

T2,p2

5. Property Determination

T2,p2

1 2 3 T pvuhs

p

v

p

v

6. Laws of ThermodynamicsQ=? W=? E=? material flows=?

2CO

Thermodynamic Problem Solving Technique

QW

QW

surroundingsW


Q

24

∂∂

+∂∂

τ+

∂∂

+∂∂

τ+

∂∂

+∂∂

τ−

∂∂

τ+∂∂

τ+∂∂

τ−

∂∂

+∂∂

+∂∂

∂∂

−

∂

∂+

∂∂

+∂∂

−=

∂∂

+∂∂

+∂∂

+∂∂

ρ

ρ+

τ

∂∂

+τ∂∂

+τ∂∂

−

∂∂

ρ+∂∂

ρ+∂∂

ρ−∂∂

−=ρ∂∂

ρ+

τ

∂∂

+τ∂∂

+τ∂∂

−

∂∂

ρ+∂∂

ρ+∂∂

ρ−∂∂

−=ρ∂∂

ρ+

τ

∂∂

+τ∂∂

+τ∂∂

−

∂∂

ρ+∂∂

ρ+∂∂

ρ−∂∂

−=ρ∂∂

−

=

∂∂

+∂∂

+∂∂

+

∂∂

+∂∂

+∂∂

+∂∂

yw

zv

xw

zu

xv

yu

zw

yv

xu

zw

yv

xu

TpT

zq

yq

xq

zTw

yTv

xTu

tTc

ENERGY

fzyxz

wwyvv

xwu

zpw

t

fzyxz

vwyvv

xvu

ypv

t

fzyxz

uwyuv

xuu

xpu

t

directions zy,x,MOMENTUM

0zwρ

yvρ

xuρ

zρw

yρv

xρu

tρ

CONTINUITY

yzxzxyzzyyxx

p

zyxv

zzzxzxz

yzyyyxy

xzxyxxx

EQUATION SUMMARY - 3D, viscous, variable density, unsteady

mae 431 energy systems i - university at buffalo · aircraft - high velocity jet transportation -...

Documents