[email protected] K5 Thermodynamics Fundamental for TKE - Share …share.its.ac.id/pluginfile.php/9444/mod_resource/content/1/K5_Thermo1.pdf · Phase 1: Virtually all the gas is

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Thermodynamics Fundamental for TKEhttp://share.its.ac.id

Dosen :Syamsul [email protected]

K5

TEKNIK KONVERSI & KONSERVASI ENERGITF 091324 / 4 SKS / Smt. 6

Fasilitator

Syamsul Arifin( [email protected] )

2011

Teknik Konversi Energi

http://share.its.ac.id

Energy Conversion

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Energy Source and Conversion Processes

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Energy Conversion Technologies

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Laws of Thermodynamics

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Entropy

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Carnot Heat Engine

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The Carnot Cycle

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Q1

Q2

The Carnot Cycle

….1

….2

….3

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The Carnot Cycle

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Stirling Engine

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Stirling Engine

Stirling Engine

Thermodynamic Processes in β Configuration

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Thermodynamic Processes in β Configuration

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Thermodynamic Processes in a Ideal Stirling Cycle

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Wout

Vmin

Vmax

TH

TL

QH

Efficiency of an Ideal Stirling Cycle

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Mot

or B

akar

Dal

am

Phase 1:Virtually all the gas is in the compression space at ambient temperature and the displacer is in the tip of the cold finger. In this phase the pistons are driven inwards, compressing the gas. This proces is nearly isothermal, the heat output Qc being dissipated via heat sinks around the compressor and the base of the cold finger. Phase 2:The pistons have reached the end of the compression stroke, the gas in the compression space is at ambient temperature and the displacer has not yet moved. This is the situation at the start of Phase II. Throughout this phase the pistons remain stationary and hence the total volume of gas remains constant. The displacer moves downwards as its spring compresses and gas flows through the regenerator, giving up heat Qr in the proces. This heat is stored in the renegeratoruntil later in the cycle. Phase 3:The pistons are driven outwards and the gas expands. This expansion process, too, is nearly isothermal, the heat input Qe being drawn from the surroundings of the expansion space. As a result refrigeration occurs at the tip of the cold finger. Phase 4:Throughout this phase the pistons remain stationary. The displacer, however, moves upwards because of the lower gas pressure in the expansion space. Gas from the expansion space therefor flows back through the regenerator, taking up the stored heat Qr in the process and re-entering the compression space at ambient temperature.

Figure 1 - The Sunpower EG-1000 free-piston Stirling engine/generator

The linear electrical generator is comprised of powerful rare-earth magnets in the piston cutting a magnetic circuit and coils in the cylinder. This produces 240 Volts at 50 Herz - designed for operation in Europe, and is capable of producing more than one kilowatt of electrical power output at around 90% efficiency. The hot water is provided by operating the cooling water at a temperature of 50°C.

In this photograph we see the Sunpower EG-1000 being demonstrated using sawdust pellets as the fuel, and generating more than 1000W of electricity to a light panel. This was done at the Sustainability Fair in the Fairgrounds of Athens Ohio, 2001. A closeup photograph of the basic system is shown. Notice the closed cycle radiator and vibration pump used in the water cooling system.

Stirling Engine Analysis

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Stirling Engine Analysis

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Stirling Engine Analysis

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Stirling Engine Analysis

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Stirling Engine Analysis

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Stirling Engine Analysis

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Stirling Engine Analysis

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Stirling Engine Analysis

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Stirling Engine Analysis

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Solar Dish Stirling System

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Solar Dish Stirling System Efficiency

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Rankin Cycle Engine

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Rankine Cycle Efficiency

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Ideal Reheat Rankine Cycle

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Organic Rankine Cycle

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Temperature Dependence of Rankine Cycle Devices

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Cycle Efficiencies with Heat Engines

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Organic Rankine Cycle

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Externally Heated Systems

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Cogeneration

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Internal Combustion EnginesAir Standard Cycles

Spark ignition

Number of StrokesFour stroke

Two stroke

Cylinder Design•Small engines usually have one or two cylinders, but may have as many as four.

Three Common Cylinder Orientations For Single Cylinder Engines

VerticalHorizontal

Slanted

Cylinder Design-cont.

V

Horizontally opposed

In-line

Three common cylinder configuration in multiple cylinder engines:

Hor izontal

Ver tical

Small gas engines use three crankshaft orientations:

Cylinder Design-cont.

Multi-position

Otto Cycle P-V & T-s Diagrams

Pressure-Volume Temperature-Entropy

Otto Cycle Derivation

• Thermal Efficiency:

– For a constant volume heat addition (andrejection) process;

– Assuming constant specific heat:

QQ - 1 =

QQ - Q =

H

L

H

LHthη

T C m = Q vin ∆

1-TTT

1 - TTT

-1 =)T - T( C m)T - T( C m - 1 =

2

32

1

41

23v

14vthη

Otto Cycle Derivation

T C m = Q v ∆Rej

• For an isentropic compression (and expansion) process:

• where: γ = Cp/Cv

• Then, by transposing,

TT =

VV =

VV =

TT

4

3

3

41-

2

11-

1

2

γγ

TT =

TT

1

4

2

3

Otto Cycle Derivation

TT-1 =

2

1thηLeading to

The compression ratio (rv) is a volume ratioand is equal to the expansion ratio in an ottocycle engine.

• Compression Ratio

VV =

VV = r

3

4

2

1v

1 + vv = r

vv + v =

volume Clearancevolume Total = r

cc

sv

cc

ccsv

where Compression ratio is defined as

Otto Cycle Derivation

• Then by substitution,

)r(1 - 1 = )r( - 1 = 1-v

-1vth γ

γη

)r( = VV =

TT -1

v1

2-1

2

1 γγ

The air standard thermal efficiency of the Otto cycle then becomes:

Otto Cycle Derivation

• Summarizing

QQ - 1 =

QQ - Q =

H

L

H

LHthη T C m = Q v ∆

1-TTT

1 - TTT

-1 =

2

32

1

41

thη

)r( = VV =

TT -1

v1

2-1

2

1 γγ

)r(1 - 1 = )r( - 1 = 1-v

-1vth γ

γη

TT =

TT

1

4

2

3

2

11TT th −=η

where

and then

Isentropic behavior

Otto Cycle Derivation

• Heat addition (Q) is accomplished through fuel combustion

• Q = Lower Heat Value (LHV) BTU/lb, kJ/kg

Q AF m =Q

fuelain

cycle

Otto Cycle Derivation

T C m = Q vin ∆

also

Otto Cycle Analysis

• Determine the temperatures and pressures at each point in the Otto Cycle.

Compression Ratio = 9.5:1T1 temperature = 25oC = 298oKP1 pressure = 100 kPa

Otto Cycle P & T Prediction

Diesel Cycle Derivation

Diesel Cycle P-V & T-s Diagrams

Diesel Cycle Derivation

• Thermal Efficiency (Diesel):

QQ - 1 =

QQ - Q =

H

L

H

LHthη

T C m = Q p ∆

For a constant pressure heat addition process;

For a constant volume heat rejection process;

T C m = Q v ∆

Assuming constant specific heat:

1-TTT

1 - TTT

- 1 =)T - T( C m)T - T( C m - 1 =

2

32

1

41

23p

14vth

γη where: γ = Cp/Cv

• For an isentropic compression (and expansion) process:

• However, in a Diesel

• The compression ratio (rv) is a volume ratio and, in a diesel, is equal to the product of the constant pressure expansion and the expansion from cut-off.

TT =

VV

VV =

TT

4

3

3

41-

2

11-

1

2

γγ

VV

VV V = V

3

4

2

141 ≠

Diesel Cycle Derivation

• Compression Ratio

• Then by substitution,VV

VV = r

3

4

2

1vc

≠vV

VV = r r = r

4

3

3

2ecpvc

••

( )

1)-r(1 - r

)r(1 - 1 =

cp

cp1-

vth γ

ηγ

γ

)r( = VV =

TT -1

v1

2-1

2

1 γγ

Diesel Cycle Derivation

Diesel Cycle Analysis

• Determine the temperatures and pressures at each point in the Diesel Cycle.

Compression Ratio = 20:1T1 temperature = 25oC = 298oKP1 pressure = 100 kPa

Diesel Cycle P & T Prediction

Otto-Diesel Cycle Comparison

Dual Cycle P-V Diagrams:

• Dual Cycle Thermal Efficiency

5.2

3

VV

PP =

2

3 =βα

)T - T( C m + )T - T( C m = Q 2.53p22.5vin

1)-( + 1)-(1 -

CR1 - 1 =

1)-(

βγααβαη

γγ

Dual Cycle Efficiency

where: γ = Cp/Cv

( )14Rej TT C m = Q v −

• Critical Relationships in the process include

)r( = VV =

TT -1

v1

2-1

2

1 γγ

Q AF m =

cycleQ

fuela

( )r = VV =

PP

v2

1

1

2 γγ

Diesel Cycle Derivation

T C m = Q p ∆ T C m = Q v ∆

( )

1)-r(1 - r

)r(1 - 1 =

cp

cp1-

vth γ

ηγ

γ