ข้อสอบสามัญเครื่องกล Power Plant 3/2547

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2 (Power Plant / Gas Turbine) 3/2547

6 4

POWER PLANT 1 - 3 2

GAS TURBINE 4 - 6 2

POWER PLANT

1. Ideal Saturated Rankine Cycle Power Plant

40 bar (Saturated Temperature 250.3o

C) Condenser 0.10 bar (Saturated Temperature 45.8

oC) -

(25 ) 40 bar hf= 1,087 kJ/kg , h g = 2,801 kJ/kg ,

sf= 2.797 kJ/kg-K , s g = 6.070 kJ/kg-K

0.10 bar hf= 191.83 kJ/kg , h g = 2,584.7 kJ/kg ,s

f= 0.6493 kJ/kg-K , s

g= 8.1502 kJ/kg-K

1.1 Rankine Cycle (Qin)1.2 Rankine Cycle (Qout)1.3 Rankine Cycle (Win)1.4 Rankine Cycle (Wnet)1.5 Rankine Cycle

40 bar hf= 1,087 kJ/kg , h g = 2,801 kJ/kg ,

sf= 2.797 kJ/kg-K , s g = 6.070 kJ/kg-K

0.10 bar hf= 191.83 kJ/kg , h g = 2,584.7 kJ/kg ,s

f= 0.6493 kJ/kg-K , s

g= 8.1502 kJ/kg-K

h1 = 191.83 kJ/kg

h3 = 2,801 kJ/kg

s3 = 6.070 kJ/kg-K

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1W2 = -v*(P2 P1) = h1 h2

= - 0.00101 * (4000 10)

= - 4.03 kJ/kg

h2 = h1 + Wp

= 191.83 + 4.03 kJ/kg

= 195.86 kJ/kg

s4 = s3 = 6.070 kJ/kg-K

x4 = (s4 - 0.6493) / (8.1502 - 0.6493)

= 0.7227

h4 = hf + x4 * (hg hf)

= 191.83 + 0.7227 *(2,584.7 - 191.83)

= 1921.09 kJ/kg

Wt = h3 h4

= 2,801 - 1921.09

= 879.91 kJ/kg

1.1 Qin = h3 h2

= 2,801.4 - 195.86

= 2605.14 kJ/kg

1.2 Qout = h4 h1

= 192109 - 191.83

= 1729.26 kJ/kg

1.3 Wp = 1W2 = - 4.03 kJ/kg

1.4 W = Wt + Wp

= 879.91 4.03

= 875.88 kJ/kg

1.5 Eff = W/Qin

= 875.88 / 2605.14

= 33.62 %

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2. Superheated Rankine Cycle Power Plant (SuperheatedSteam) 30 bar Steam Temperature 300 oC Condenser 0.10 bar (Saturated Temperature 45.8 oC) - (25 )

30 bar hf= 1,008.42 kJ/kg , h g = 2,804.2 kJ/kg ,

sf= 2.6457 kJ/kg-K , s g = 6.1869 kJ/kg-K

300oC h = 2,995 kJ/kg , s = 6.5410 kJ/kg-K

0.10 bar hf= 191.83 kJ/kg , h g = 2,584.7 kJ/kg ,sf= 0.6493 kJ/kg-K , s g = 8.1502 kJ/kg-K

2.1 Rankine Cycle (Qin)2.2 Rankine Cycle (Qout)2.3 Rankine Cycle (Win)2.4 Rankine Cycle (Wnet)2.5 Rankine Cycle

30 bar hf= 1,008.42 kJ/kg , h g = 2,804.2 kJ/kg ,

sf= 2.6457 kJ/kg-K , s g = 6.1869 kJ/kg-K

300oC h = 2,995 kJ/kg , s = 6.541 kJ/kg-K

0.10 bar hf= 191.83 kJ/kg , h g = 2,584.7 kJ/kg ,sf= 0.6493 kJ/kg-K , s g = 8.1502 kJ/kg-K

h1 = 191.83 kJ/kg

h3 = 2,995 kJ/kg

s3 = 6.541 kJ/kg-K

1W2 = -v*(P2 P1) = h1 h2

= - 0.00101 * (3,000 10)

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= - 3.02 kJ/kg

h2 = h1 + Wp

= 191.83 + 3.02 kJ/kg

= 194.85 kJ/kg

s4 = s3 = 6.541 kJ/kg-K

x4 = (s4 - 0.6493) / (8.1502 - 0.6493)

= 0.7855

h4 = hf + x4 * (hg hf)

= 191.83 + 0.7855*(2,584.7 - 191.83)

= 2071.35 kJ/kg

Wt = h3 h4

= 2,995 - 2071.35

= 923.65 kJ/kg

2.1 Qin = h3 h2

= 2800.15 kJ/kg

2.2 Qout = h4 h1

= 1879.52 kJ/kg

2.3 Wp = 1W2 = 3.02 kJ/kg

2.4 W = Wt + Wp

= 923.65 3.02

= 920.63 kJ/kg

2.5 Eff = W/Qin

= 32.88 %

3. Carnot Ideal Cycle 2 ReversibleIsothermal Processes Reversible Adiabatic Processes(Isentropic) Ideal Saturated Rankine Cycle

(25 )

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CARNOT CYCLE SATURATED RANKINE CYCLE

1. Condenser() Condenser

(x1) Entropy Saturated Entropy, sf (P2- BoilerPressure)

1. Condenser () Condenser

(Saturated Liquid) Condenser

2. Pump (x1) Condenser Pump Power

2. Condenser (Boiler) Pump Power Pump

GAS TURBINE

4. (30 ) (25 )1) ......2) 1 specific work................3)

............................. ..................... ..................................4) Regenerator .....................................

5) Reheater ...........................

6) ...............

................................... (//)7) ...............

......................................................................................................................................................................

8) Stagnation temperature ..........................................................................................................

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9) twin spool ...................................................................10) 1. .................... 2. ..

3. .. 4.

11) propelling nozzle ........................................ 12) Propelling nozzle subsonic convergent nozzle

supersonic ......................................................................................................................................... 13) ................................................................................................ 14) ................................................................15) Power plant Cogeneration ...........................................

.......................................................................................................................................................................

T 3 16) 2-5 .

17) ...............................................................

18) ...............................................................

19) Ram compression ...........................................................................................................................................................................................................................................................................

20) exhaust diffuser.......................................................................................

2

45

2

S

1

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4 (Automotive / ICE) 3/2547

1)

2) 3) , , 4) 5) 6) , 7) 8)

9) 2 10) , , 11) 12) Convergent divergent nozzle

13)

14) Ft = (Mc.Cjc + Mh.Cjh) - MaCa

15) Industrial Gas Turbine

16) Regenerator

17)

18)

19)

20)

5. combined cycle gas turbine 4 waste heat boiler gas turbine boiler 4 steam turbine 1 gas turbine 1 60 MW steam turbine 120 MW

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gas turbine compressor, combustion chamber, turbine generator

60 MW 300 K, 1.01325 barisentropic efficiency compressor 80 %combustion efficiency 97 %

isentropic efficiency turbine 86 %transmission efficiency 99 %

pressure drop combustion chamber 0.04 bar gases turbine 930 0C turbine 1.2 bar, 505 0C 33.5 MJ/m3

specific fuel consumption gas turbine

(CPa) = 1.005 kJ/kgK gases (CPg) = 1.147 kJ/kgK isentropic (a) = 1.4 isentropic gases (g) = 1.333

( R ) = 0.287 kJ/kgK(25 )

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6. gas turbine 2 stages high pressure stage gas turbine low-pressure stage gas turbine high pressure stage compressor low-pressure stage (propeller) = 4 : 1 60 kg/s turbine 6500 C compressor = 1.01 bar, 250C isentropic efficiencies compressor, high-pressure low-pressure stage turbines 80%,83% 85% mechanical efficiency 98% combustion chamber

. turbine 2 stages . Cycle efficiency.

(CPa CPg) 1.005 1.15kJ/kgK (a g ) 1.4 1.333

(25 )

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ข้อสอบสามัญเครื่องกล Power Plant 3/2547