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Chapter 1 Ref Tech2 - · PDF fileلوﻷا بﺎﺒﻟا ﺪﻳﺮﺒﺘﻟا ﺮﺋاود ﻰﻓ ﻢﻜﺤﺘﻟا ﺔﻤﻈﻧأ Control systems in Refrigeration cycles
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-
) (
" "
.
.
-
Control systems in Refrigeration cycles
Flow Control(
Devices ( (
Temperature Control Devices (
Electric Circuits Control Devices(
)
.
)Refrigerant Control Devices(
"
) (
) Expansion device(
) -(
: -
- Evaporation 14
process at p=c
- Isentropic 21
compression at s=c
- Condensation 32
process at p=c
- ( ) Throttling 43
process at i=c
) (
(
" )
. \
P-I ) -(
.
:
.
) Hand Expansion Valve(
) Nozzle(
)-(
(
)
.
.
.
. ) -(
"
"
.
"
" .
. "
.
) Automatic Expansion Valve(
"
" ) -( .
U ( ) ( )
.
.
F1 F2
.
(
)
.
F F Fp1 2= + (1-1)
. ) -(
) -(
.
.
"
.
.
.
.
"
.
"
"
) (
-( "
.)
. ) -(
.
). ( ) -(
"
"
"
.
"
"
.
) Thermostatic Expansion Valve(
"
.
.
) -( "
"
"
"
" ( ")
"
"."
. ) -(
) -(
U
( )
) ( "
"
.
.
F1
F2 Fp
.
"
.
( )
"
.
"
.
"
" ( )
) (
". "
" "
.
oC 6 T1
P1
) (
oC 6
P2 " T2
"
.
) Flash Gas(
(
)
"
"
"
) -(
3
: "
& & &m m mf l= + (1-2)
& .i & .i & .i( & & ).i & .i & .im m mm m m m
f l
f l f l
4 1 5
4 1 5
= +
+ = +
&& .( )( )
mm i i
i ifl=
4 5
1 4 (1-3)
. ) -(
\
\
.
). -(
" \
).-(
. ) -(
. ) -(
&& .( )(
\
\)m
m i ii if
l=
4 5
1 4 (1-4)
) -( ) -(
"
.
" .
"
"
"
) -(
.
. "
"
.
.
. ) -(
"
"
" "
.
.
"
"
.
. ) -(
)-( 10
"
" .
10
. 4
.
.
"
.
) -(
.
bar 1.8
oC 5.6
bar 2.30
bar 1.77
5.6 oC )0.53 bar (
.
bar 1.77
bar 2.30
bar 1.77
.
)-(
.
. ) -(
" "
"
.
" "
"
"
0.3~0.6 bar.
"
"
).-(
. ) -(
" "
oC 7 ) -(
bar 0.35 oC 3
oC 29- bar 0.35
oC 7
" "
.
) Liquid Charged(
) -(
- to 4.4
28.9 oC
.
) -(
.
A ) -(
B
C 5.6 oC
.
) Liquid Cross Charged(
. ) -(
.
A
B
C
" oC 40- ~ 4.4
.
. ) -(
A " B
X
" "
.
. "
"
.
.
) gedVapor Char(
)-(
1.1- ~ 15.6 oC ,
.
. ) -(
A
B
D "
C
.
) Vapor Cross Charged(
) -(
.
) Carbon or Silica gel(
) (Carbon dioxide
"
.
"
) -(
" "
"
.
. ) -(
(
" " ) " "
: ) -(
- -
- - (
).
.
) (
"
.
) -(
.
"
.
" "
( )
.
"
(
)
"
.
Electric Expansion -Thermal(
Valve (
(
Thermistor ( )Solid-State Semiconductor (
(
Lithium Chloride ( oC 1 % 6
-(
) Low Voltage(
Transformer ( "
)-( ) Bimetal(
). Soft( ) Hard(
. ) -(
) -(
.
) A (
oC 6
). -(
) Solenoid Valve(
.
) Capacity of Expansion Valve(
:
. ) Nozzle ( .
. ( ) (
).
.
Flash gas(
. )
. .
" "
