11-59 Consider a two-stage cascade refrigeration system operating between the pressure limits of 1.4 MPa and 160 kPa with refrigerant-134a as the working fluid. Heat rejection from the lower cycle to the upper cycle takes place in an adiabatic counterflow heat exchanger where the pressure in the upper and lower cycles are 0.4 and 0.5 MPa, respectively. In both cycles, the refrigerant is a saturated liquid at the condenser exit and a saturated vapor at the compressor inlet, and the isentropic effi- ciency of the compressor is 80 percent. If the mass flow rate of the refrigerant through the lower cycle is 0.25 kg/s, determine (a) the mass flow rate of the refrigerant through the upper cycle, (b) the rate of heat removal from the refrigerated space. and (c) the COP of this refrigerator. Answers: (a) 0.384 kg/s (b) 42.0 kW, (c) 2.12
11-59 Consider a two-stage cascade refrigeration system operating between the pressure limits of 1.4 MPa and 160 kPa with refrigerant-134a as the working fluid. Heat rejection from the lower cycle to the upper cycle takes place in an adiabatic counterflow heat exchanger where the pressure in the upper and lower cycles are 0.4 and 0.5 MPa, respectively. In both cycles, the refrigerant is a saturated liquid at the condenser exit and a saturated vapor at the compressor inlet, and the isentropic effi- ciency of the compressor is 80 percent. If the mass flow rate of the refrigerant through the lower cycle is 0.25 kg/s, determine (a) the mass flow rate of the refrigerant through the upper cycle, (b) the rate of heat removal from the refrigerated space. and (c) the COP of this refrigerator. Answers: (a) 0.384 kg/s (b) 42.0 kW, (c) 2.12
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
Problem 1.1MA
Related questions
Question
Determine:
Work done by the system
Total Heat that was added
Change in internal energy
Heat transferred in the heat exchanger
![Sort
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
P₁
[kPa]
160
500
500
160
400
1400
1400
t₁
[K]
-15.6
21.1
15.71
-15.6
8.91
56.71
52.4
8.91
In
X₁
no
1
0
1
0
h₁
[kJ/kg]
241.1
270.4
73.33
73.33
255.6
288
127.2
127.2
nin
hs
[kJ/kg]
264.5
281.5
S₁
[kJ/kg*K]
0.9419
0.9419
0.2802
0.2905
0.9269
0.9269
0.4532
0.472
11.10 "Tamna
Unit Settings: SI C kPa kJ mass deg
COP = 2.122
na=0.8
QT = 49.26 [kW]
ma = 0.3839 [kg/s]
nb = 0.8
Win = 19.77 [kW]
mb = 0.25 [kg/s]
QL = 41.95 [kW]
Click on this line to see the array variables in the Arrays Table window
7 potential unit problems were detected.
Compilation time = 125 ms
COP = 16
Check Units
Calculation time = 16 ms
ma = 114181 Ikast mb = 11 25 1kg/s](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F78386da1-fb59-49fe-97c0-6cacd337937b%2Fe8942b2f-52f1-4fbe-8e82-44d4e70612a4%2F7nc4b5a_processed.png&w=3840&q=75)
Transcribed Image Text:Sort
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
P₁
[kPa]
160
500
500
160
400
1400
1400
t₁
[K]
-15.6
21.1
15.71
-15.6
8.91
56.71
52.4
8.91
In
X₁
no
1
0
1
0
h₁
[kJ/kg]
241.1
270.4
73.33
73.33
255.6
288
127.2
127.2
nin
hs
[kJ/kg]
264.5
281.5
S₁
[kJ/kg*K]
0.9419
0.9419
0.2802
0.2905
0.9269
0.9269
0.4532
0.472
11.10 "Tamna
Unit Settings: SI C kPa kJ mass deg
COP = 2.122
na=0.8
QT = 49.26 [kW]
ma = 0.3839 [kg/s]
nb = 0.8
Win = 19.77 [kW]
mb = 0.25 [kg/s]
QL = 41.95 [kW]
Click on this line to see the array variables in the Arrays Table window
7 potential unit problems were detected.
Compilation time = 125 ms
COP = 16
Check Units
Calculation time = 16 ms
ma = 114181 Ikast mb = 11 25 1kg/s
Transcribed Image Text:11-59 Consider a two-stage cascade refrigeration system
operating between the pressure limits of 1.4 MPa and 160 kPa
with refrigerant-134a as the working fluid. Heat rejection from
the lower cycle to the upper cycle takes place in an adiabatic
counterflow heat exchanger where the pressure in the upper and
lower cycles are 0.4 and 0.5 MPa, respectively. In both cycles,
the refrigerant is a saturated liquid at the condenser exit and a
saturated vapor at the compressor inlet, and the isentropic effi-
ciency of the compressor is 80 percent. If the mass flow rate of
the refrigerant through the lower cycle is 0.25 kg/s, determine
(a) the mass flow rate of the refrigerant through the upper
cycle, (b) the rate of heat removal from the refrigerated space.
and (c) the COP of this refrigerator. Answers: (a) 0.384 kg/s
(b) 42.0 kW, (c) 2.12
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