162
Md. A. Islam and B. B. Saha
(a) Room air-conditioning cycle with R32.
(b) Medium temperature (–7 °C) refrigeration cycle with R134a.
(c) Low temperature (–25 °C) refrigeration cycle with R404A.
Critical Point,
414.15, 5782.64
700
7000
150
250
350
450
550
650
Pressure (kPa)
Enthalpy (kJ kg -1 )
d' d
a a'
c' c
b
b' b"
Critical Point,
1.649, 78.105
-20
0
20
40
60
80
100
0.50 0.80 1.10 1.40 1.70 2.00 2.30 2.60
Temperature (°C)
Entropy (kJ kg -1 K -1 )
d' d
a
c
b
c'
b'
b"
a'
Critical Point,
390.94, 4059.02
100
1000
10000
100
200
300
400
500
Pressure (kPa)
Enthalpy (kJ kg -1 )
d' d
a a'
c' c
b b' b"
Critical Point,
1.559, 101.059
-30
0
30
60
90
120
0.60
0.90
1.20
1.50
1.80
2.10
Temperature (°C)
Entropy (kJ kg -1 K -1 )
d' d
a
c
b
c'
b'
b"
a'
Critical Point,
1.445, 72.117
-50
-20
10
40
70
100
0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
Temperature (°C)
Entropy (kJ kg -1 K -1 )
d' d
a
c
b
c'
b'
b"
a'
Critical Point,
345.21, 3734.70
100
1000
10000
100
150
200
250
300
350
400
450
Pressure (kPa)
Enthalpy (kJ kg -1 )
d' d
a a'
c' c
b b' b"
Fig. 9.3 T-s and P-h diagram for various cooling applications
Electric power consumption is dependent on the COP of and can be determined
by the following equation,
E p =
Q c
C O P
(9.13)
The mass flow rate of the refrigerant can be calculated by the following equation,
˙
m =
h a − h d
Q c
(9.14)