alcorcon fluid machineries reviewer

8/18/2019 alcorcon Fluid Machineries reviewer

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Formulas for the subcooling cycle

1. (egerating *+ect, (*:

ℜ=h1

−h4

'

2. ass -o$ rate per ton m/ :

m' =

211

h1−h

4' =

kg

min−km

Where/ = mass -o$ rate per ton #or the subcoole! cycle

". Volume -o$ rate at suction, V/ :

V 1' =m' ν1

Where:

ν1 = specic volume

&. Coefcient o# per#ormance, C0' :

COP=h1−h

4

h2−h1

. Compressor Wor%, Wc :

W c=m' (h2−h1)

. 3eat (e4ecte! in the con!enser, 5r :

Qr=m' (h2−h1)


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Refrigeration Cycle with superheating the suction vapour :

Formulas for the superheating Cycle

1. (e#rigerating e+ect, (*:

ℜ=h1 ' −h4

2. ass -o$ rate per Ton m/:

m' =

211

h1' −h4

= kg

min−km

Where:


4/14

m/ = mass -o$ rate per ton #or the superheate! cycle $ith use#ul

cooling

". Volume -o$ rate at suction, v/ :

V 1'

=m' ν1 '


COP= h

1 ' −h4h2 ' −h1'

. Compressor $or!, $c:

W c=m ' (h2 ' −h1 ' )

. 3eat re4ecte! om the con!enser, 5r:

Qr=m' (h2 ' −h3)

6. i# the superheating occurs $ithout use#ul cooling


ℜ=h1−h4

2. ass -o$ rate per Ton m// :

m' ' =

211

h1−h

4' =

kg

min−km

". Volume -o$ rate at suction

V 1' ' =m ' ν1

&. Coefcient o# per#ormance

COP= h

1−h

4

h2 ' −h1'


5/14

. Compressor $or%, Wc

W c=m' ' (h2 ' −h1 ' )

. 3eat re4ecte! in the con!enser, 5r

Qr=m' ' (h2 ' −ha)

Refrigeration cycle with subcooling and superheating

7ormulas #or re#rigeration cycle $ith subcooling an! superheating


ℜ=h1 ' −h4 '

2. ass -o$ rate per ton m// 8


6/14

m' = 211

h1 ' −h4 '

= kg

min−km

". Volume -o$ rate at suction, v1/

V 1' =m ' ν1 '


COP=h1 ' −h4 ' h2' −h1 '

. Compressor $or%, $c:

W c=m ' (h2 ' −h1 ' )

. 3eat re4ecte! in the con!enser, 5r

Qr=m' (h2 ' −h3)

Heat exchanger

(e#rigeration system use a li)ui!9li)ui!9to9suction heat echanger to ensure

that no li)ui! enters the compressor an! to prevent bubbles o# vapour #rom

impe!ing the -o$ o# re#rigerant through the epansion valve


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1. 3eat balance o# the heat echanger


". Coefcient o# per#ormance, C0'

ulti pressure system

; multi9pressure system us a re#rigeration system that has t$o or more lo$ si!e

pressures. The lo$ si!e pressure is the pressure o# the re#rigerant bet$een the

epansion valve an! the inta%e o# the compressor.


8/14

(emoval o# 7lash


9/14


10/14

Two evaporators and one compressor

n many situations one compressor serves t$o evaporators having !i+erent

temperature re)uirements. ;n eample is an in!ustry $hich nee!s lo$9temperature

re#rigeration #or a process an! $hich must also provi!e air con!itioning #or someofces.


11/14

1. ass -o$ rate, through high temperature evaporator, m& :

2. ass -o$ rate, through lo$ temperature evaporator, m> :

". Total mas -o$ rate, m1 :

&. 3eat balance at 4unction

m1h1=m

6h

6+m

8h8

. Compressor po$er

W =m1(h2−h1)

Two compressors and one evaporator


12/14

T$o stage compression $ith intercooling an! removal o# -ash gas us o#ten the i!eal

$ay to serve one lo$ temperature evaporator. This system re)uires less po$er than

$ith a single compressor, an! o#ten the saving po$er $ill 4usti#y the cost o# the

etra e)uipment.


13/14

1. nterme!iate pressure #or minimum $or% :

P2=√ P1 P4

2. ass -o$ rate through evaporator, m1 :

m1=refrigeratingload

h1−h

6

". ass balance in intercooler :

m2=m

7

m2=m

6

&. 3eat balance in intercooler

m2h

2+m

6h6=m

7h7+m

3h3

. ?o$ stage 'o$er :

W Low stage=m1(h2−h1)

. 3igh @ stage 'o$er


14/14

ha−h3W high stage=m3 ¿

>. Total po$er:

T$o compressor an! t$o evaporators

The system $hich has t$o evaporators operating at !i+erent temperatures is

common in in!ustrial re#rigeration. ; #roAen #oo! plant may re)uire t$o evaporators

at !i+erent temperature, one at 9&BC to )uic% #reeAe the #oo! an! the other at 92C

to hol! the #oo! a#ter it is #roAen

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