5.Materi Bab v Sistem Compressor

8/13/2019 5.Materi Bab v Sistem Compressor

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SISTEM COMPRESSOR


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FILTER


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TABEL UDARA- MOISTURE

Gambar 6.7B


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CONTOH SOAL :

KANDUNGAN MOISTURE DALAM UDARA


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REGULATOR


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REGULATOR


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TIPE REFRIGERANT DRYER

127 TEORI

Gambar 6.8


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TIPE REFRIGERANT DRYER


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TIPE ABSORPTIVE DRYER


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TIPE REGENERATIP ADSORPTIVE DRYER


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CHECK VALVEBALL CHECK VALVE

PILOT OPERATED CHECK VALVE


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PENGGUNAAN CHECK VALVE


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SUTTLE VALVE


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RELIEF VALVE


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PENGOPERASIAN

PILOTOPERATED VALVE


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CONTOH

RELIEF VALVE


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CONTOH KOMPRESSOR JENIS PISTON

TUNGGAL


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LANJUTAN


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ACCUMULATOR

BLADDER ACC DIAPRAGMA ACCDIAPRAGMA ACC


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JENIS COMPRESSOR


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CENTRIFUGAL COMPRESSOR

SINGLE STAGE

HORIZONTAL

MULTI STAGEVERTICAL


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RESISTENSI ALIRAN DAN TEKANAN

PADA KOMPRESOR SENTRIFUGAL DAN AXIAL


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AXIAL COMPRESSOR


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VANE ROTARY COMPRESSOR


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RECIPROCATING COMPRESSOR


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Compressors


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Centrifugal Compressors


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Types of Radial Flow Compressors

(multi-stag)


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Types of Reciprocating

Compressor


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Total Energy Balance

cWmQHgZu

2

2

adiabatic

compression

Note thatcin TEB includes efficiency while in

MEB does not include efficiency

12

TTCHW pc


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Isentropic Work of Compression

As a first approximation, a compressor without any internalcooling can be assumed to be adiabatic. If the process is

also assumed to be reversible, it will be isentropic.

.1

1 constpp

Solve for , substitute into MEB, and integrate


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Isentropic Work of Compression

Upon Integration

This is the isentropic (adiabatic) work of compression.

The quantity p2/p1is the compression ratio.

11

1

1

2

1

1

0

p

ppW S


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Compressor Work

Compression is not reversible, however. Deviations from

ideal behavior must be accounted for by introducing anisentropic compressor efficiency such that the true work

of compression is given by.

ad

Sc WW

0

How can adbe found?

12

TTCW pc


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Isothermal CompressionIf sufficient cooling is provided to make the compression

process isothermal, the work of compression is simply:

1

21

0 ln

p

p

M

RTW

T

For a given compression ratio and suction condition, the

work requirement in isothermal compression is less than

that for adiabatic compression. This is one reason thatcooling is useful in compressors.


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Polytropic Compression

In actuality the S = 0 path assumed in writing the

expression p/ const. is not the true thermodynamic path

followed by gases in most large compressors and the

compression is neither adiabatic not isothermal. A polytropic

path is a better representation for which:

.1

1 constpp

nn

Here ndepends on the nature of the gas and details of thecompression process.


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11

1

1

2

1

1

n

n

ppp

nnpW

wherepis the work for polytropic compression

Again the actual work of compression is larger than the

calculated work and:

p

pc

WW


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The polytropic efficiency pis often the efficiency quoted

by manufacturers. From this efficiency useful relations can

be stated to convert from polytropic to adiabatic results:

To get n the polytropic exponent:

p

pn

1 p

n

n

11

or

To get relationships between T or and compression ratiosimply replace with n.

n

n

p

p

T

Tge

1

1

2

1

2..


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Multistage Compression

Consider a two stage compression process p1p2p3with perfect intercooling (temperature reduced to T1after

each compression)

11

11

1

2

31

1

1

21

0

p

pRT

p

pRTW S

Now find p2which will minimize work, differentiate wrt p2

312 pppopt


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Multistage Compression2

1

1

3

2

3

1

2

p

p

p

p

p

p

So the compression ratio that minimizes total work is such that each

stage has an identical ratio.

This can be generalized for n stages as:n

n

p

p

p

p

p

p1

1

1

2

3

1

2

.

1

1 constp

pT

i

ii

When T is not cooled to T1:

i

ii

p

pT 1


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Isentropic Compression


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Real Compression

HIdeal HActual

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5.Materi Bab v Sistem Compressor