Refrigeration Questions and Answers – Multiple Evaporators and Compressor System – 2

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This set of Refrigeration written test Questions & Answers focuses on “Multiple Evaporators and Compressor System – 2”.

1. What is the value of enthalpy when refrigerant enters the compressor, i.e., point 1?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q1
a) m1 h11 + m2 h8 + m3 h5 / (m1 + m2 – m3)
b) m1 h11 + m2 h8 + m3 h5 / (m1 – m2 + m3)
c) m1 h11 + m2 h8 + m3 h5 / (m1 + m2 + m3)
d) m1 h5 + m2 h5 + m3 h4 / (m1 + m2 + m3)
View Answer

Answer: c
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h11 – h10
m2 = 210 Q2 / h8 – h7
m3 = 210 Q3 / h5 – h4
At point 1, mass of refrigerant coming from each evaporator is converging.
So, (m1 + m2 + m3) h1 = m1 h11 + m2 h8 + m3 h5
h1 = m1 h11 + m2 h8 + m3 h5 / (m1 + m2 + m3).
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2. What is the value of the refrigeration effect in the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q1
a) m1 (h11 – h10) + m2 (h8 – h1) + m3 (h5 – h2)
b) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4)
c) m1 (h11 – h10) + m2 (h8 – h2) + m3 (h2 – h4)
d) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h1 – h4)
View Answer

Answer: b
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h11 – h10
m2 = 210 Q2 / h8 – h7
m3 = 210 Q3 / h5 – h4
So, Refrigeration effect across EP1 = m1 (h11 – h10)
Refrigeration effect across EP2 = m2 (h8 – h7)
Refrigeration effect across EP3 = m3 (h5 – h4)
Total refrigeration effect produced in the system is the summation of refrigeration effect across each evaporator.
Total refrigeration effect = m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) = 210 (Q1 + Q2 + Q3).

3. What is the value of C.O.P. in the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q1
a) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) / (m1 + m2 + m3) (h2 – h3)
b) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) / (m1 + m2 + m3) (h2 – h7)
c) m1 (h11 – h10) + m3 (h8 – h7) + m2 (h5 – h4) / (m1 + m2 + m3) (h2 – h1)
d) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) / (m1 + m2 + m3) (h2 – h1)
View Answer

Answer: d
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h11 – h10
m2 = 210 Q2 / h8 – h7
m3 = 210 Q3 / h5 – h4
So, Refrigeration effect across EP1 = m1 (h11 – h10)
Refrigeration effect across EP2 = m2 (h8 – h7)
Refrigeration effect across EP3 = m3 (h5 – h4)
Total refrigeration effect produced in the system is the summation of refrigeration effect across each evaporator.
Total refrigeration effect = m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) = 210 (Q1 + Q2 + Q3)
Work = (m1 + m2 + m3) (h2 – h1)
C.O.P. = Total refrigeration effect / Work
= m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) / (m1 + m2 + m3) (h2 – h1)
= 210 (Q1 + Q2 + Q3) / (m1 + m2 + m3) (h2 – h1).
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4. What is the value of enthalpy when refrigerant enters the compressor, i.e., point 1?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q1
a) me1 h11 + me2 h9 + me3 h6 / (me1 + me2 + me3)
b) me1 h11 + me2 h9 + me3 h5 / (me1 + me2 + me3)
c) me1 h11 + me2 h8 + me3 h6 / (me1 + me2 + me3)
d) m1 h5 + m2 h5 + m3 h4 / (m1 + m2 + m3)
View Answer

Answer: a
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = me1 = 210 Q1 / h11 – h10
m2 = 210 Q2 / h9 – h7, me2 = m2 + me1 (x7 / 1 – x7)
m3 = 210 Q3 / h6 – h4, me3 = m3 + (me1 + me2) (x4 / 1 – x4)
At point 1, mass of refrigerant coming from each evaporator is converging.
So, (me1 + me2 + me3) h1 = me1 h11 + me2 h9 + me3 h6
h1 = me1 h11 + me2 h9 + me3 h6 / (me1 + me2 + me3).

5. What is the value of the refrigeration effect in the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q1
a) m1 (h11 – h10) + m2 (h8 – h1) + m3 (h5 – h2)
b) m1 (h11 – h10) + m2 (h9 – h7) + m3 (h6 – h4)
c) m1 (h11 – h10) + m2 (h8 – h2) + m3 (h2 – h4)
d) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h1 – h4)
View Answer

Answer: b
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h11 – h10
m2 = 210 Q2 / h9 – h7
m3 = 210 Q3 / h6 – h4
So, Refrigeration effect across EP1 = m1 (h11 – h10)
Refrigeration effect across EP2 = m2 (h9 – h7)
Refrigeration effect across EP3 = m3 (h6 – h4)
Total refrigeration effect produced in the system is the summation of refrigeration effect across each evaporator.
Total refrigeration effect = m1 (h11 – h10) + m2 (h9 – h7) + m3 (h6 – h4) = 210 (Q1 + Q2 + Q3).
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6. What is the value of C.O.P. in the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q1
a) m1 (h11 – h10) + m2 (h9 – h7) + m3 (h6 – h4) / (me1 + me2 + me3) (h2 – h1)
b) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) / (m1 + m2 + m3) (h2 – h7)
c) m1 (h11 – h10) + m2 (h9 – h7) + m3 (h6 – h1) / (me1 + me2 + me3) (h2 – h8)
d) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) / (m1 + m2 + m3) (h2 – h1)
View Answer

Answer: a
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h11 – h10
m2 = 210 Q2 / h9 – h7
m3 = 210 Q3 / h6 – h4
So, Refrigeration effect across EP1 = m1 (h11 – h10)
Refrigeration effect across EP2 = m2 (h9 – h7)
Refrigeration effect across EP3 = m3 (h6 – h4)
Total refrigeration effect produced in the system is the summation of refrigeration effect across each evaporator.
Total refrigeration effect = m1 (h11 – h10) + m2 (h9 – h7) + m3 (h6 – h4) = 210 (Q1 + Q2 + Q3)
Work = (me1 + me2 + me3) (h2 – h1)
C.O.P. = Total refrigeration effect / Work
= m1 (h11 – h10) + m2 (h9 – h7) + m3 (h6 – h4) / (me1 + me2 + me3) (h2 – h1)
= 210 (Q1 + Q2 + Q3) / (me1 + me2 + me2) (h2 – h1).

7. What is the value of the refrigeration effect in the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q7
a) m1 (h1 – h10) + m2 (h8 – h1) + m3 (h5 – h2)
b) m1 (h1 – h10) + m2 (h8 – h7) + m3 (h5 – h4)
c) m1 (h1 – h10) + m2 (h3 – h9) + m3 (h5 – h8)
d) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h1 – h4)
View Answer

Answer: c
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h1 – h10
m2 = 210 Q2 / h3 – h9
m3 = 210 Q3 / h5 – h8
So, Refrigeration effect across EP1 = m1 (h1 – h10)
Refrigeration effect across EP2 = m2 (h3 – h9)
Refrigeration effect across EP3 = m3 (h5 – h8)
Total refrigeration effect produced in the system is the summation of refrigeration effect across each evaporator.
Total refrigeration effect = m1 (h1 – h10) + m2 (h3 – h9) + m3 (h5 – h8) = 210 (Q1 + Q2 + Q3).
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8. What is the value of total power required to run the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q7
a) m1 (h2 – h1) + m3 (h4 – h3) + m2 (h6 – h1)
b) m1 (h2 – h1) + m2 (h4 – h3) + m3 (h6 – h5)
c) m2 (h2 – h1) + m3 (h4 – h3) + m1 (h6 – h5) / 60
d) m1 (h2 – h1) + m2 (h4 – h3) + m3 (h6 – h5) / 60
View Answer

Answer: d
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through compressors C1, C2 and C3
So, Power required to run compressor C1 = m1 (h2 – h1) / 60
Power required to run compressor C2 = m2 (h4 – h3) / 60
Power required to run compressor C3 = m3 (h6 – h5) / 60
Total power required to run the system will be summation of power required to run each compressor.
Total power required to run the system = m1 (h2 – h1) + m2 (h4 – h3) + m3 (h6 – h5) / 60.

9. What is the value of C.O.P. in the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q7
a) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) / (m1 + m2 + m3) (h2 – h3)
b) m1 (h1 – h10) + m2 (h3 – h9) + m3 (h5 – h8) / m1 (h2 – h1) + m2 (h4 – h3) + m3 (h6 – h5)
c) m1 (h1 – h10) + m2 (h3 – h9) + m3 (h5 – h8) / m1 (h2 – h1) + m2 (h4 – h2) + m3 (h6 – h3)
d) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h5 – h4) / (m1 + m2 + m3) (h2 – h1)
View Answer

Answer: b
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h1 – h10
m2 = 210 Q2 / h3 – h9
m3 = 210 Q3 / h5 – h8
So, Refrigeration effect across EP1 = m1 (h1 – h10)
Refrigeration effect across EP2 = m2 (h3 – h9)
Refrigeration effect across EP3 = m3 (h5 – h8)
Total refrigeration effect produced in the system is the summation of refrigeration effect across each evaporator.
Total refrigeration effect = m1 (h1 – h10) + m2 (h3 – h9) + m3 (h5 – h8) = 210 (Q1 + Q2 + Q3)
Total Work = m1 (h2 – h1) + m2 (h4 – h3) + m3 (h9 – h5)
C.O.P. = Total refrigeration effect / Work
= m1 (h1 – h10) + m2 (h3 – h9) + m3 (h5 – h8) / m1 (h2 – h1) + m2 (h4 – h3) + m3 (h6 – h5)
= 210 (Q1 + Q2 + Q3) / m1 (h2 – h1) + m2 (h4 – h3) + m3 (h9 – h5).
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10. What is the value of the refrigeration effect in the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q10
a) m1 (h1 – h12) + m2 (h3 – h10) + m3 (h5 – h8)
b) m1 (h11 – h10) + m2 (h9 – h7) + m3 (h6 – h4)
c) m1 (h1 – h12) + m2 (h9 – h10) + m3 (h5 – h4)
d) m1 (h11 – h10) + m2 (h8 – h7) + m3 (h1 – h4)
View Answer

Answer: a
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h1 – h12
m2 = 210 Q2 / h3 – h10
m3 = 210 Q3 / h5 – h8
So, Refrigeration effect across EP1 = m1 (h1 – h12)
Refrigeration effect across EP2 = m2 (h3 – h10)
Refrigeration effect across EP3 = m3 (h5 – h8)
Total refrigeration effect produced in the system is the summation of refrigeration effect across each evaporator.
Total refrigeration effect = m1 (h1 – h12) + m2 (h3 – h10) + m3 (h5 – h8) = 210 (Q1 + Q2 + Q3).

11. What is the value of total work done in the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q10
a) me1 (h2 – h1) + me2 (h4 – h3) + me3 (h4 – h5)
b) me1 (h2 – h1) + me3 (h4 – h3) + me2 (h6 – h5)
c) me1 (h2 – h1) + me3 (h4 – h3) + me3 (h6 – h5)
d) m1 h5 + m2 h5 + m3 h4 / (m1 + m2 + m3)
View Answer

Answer: c
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = me1 = 210 Q1 / h1 – h12
m2 = 210 Q2 / h3 – h10, me2 = m2 + me1 (x10 / 1 – x10)
m3 = 210 Q3 / h5 – h8, me3 = m3 + (me1 + me2) (x8 / 1 – x8)
Total work done is the summation of work done by each compressor.
So, Work done by compressor C1 = me1 (h2 – h1)
Work done by compressor C2 = me2 (h4 – h3)
Work done by compressor C3 = me3 (h6 – h5)
Total work = me1 (h2 – h1) + me2 (h4 – h3) + me3 (h6 – h5).

12. What is the value of C.O.P. in the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q10
a) m1 (h1 – h12) + m2 (h3 – h10) + m3 (h5 – h8)
b) m1 (h1 – h12) + m2 (h3 – h10) + m3 (h5 – h8) / me1 (h2 – h1) + me2 (h4 – h3) + me3 (h6 – h5)
c) m1 (h1 – h12) + m2 (h3 – h10) + m3 (h5 – h8) / me1 (h2 – h5) + me2 (h4 – h2) + me3 (h6 – h5)
d) m1 (h1 – h12) + m2 (h3 – h10) + m3 (h5 – h8) / me1 (h2 – h1) + me2 (h4 – h1) + me3 (h6 – h1)
View Answer

Answer: b
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h1 – h12
m2 = 210 Q2 / h3 – h10
m3 = 210 Q3 / h5 – h8
So, Refrigeration effect across EP1 = m1 (h1 – h12)
Refrigeration effect across EP2 = m2 (h3 – h10)
Refrigeration effect across EP3 = m3 (h5 – h8)
Total refrigeration effect produced in the system is the summation of refrigeration effect across each evaporator.
Total refrigeration effect = m1 (h1 – h12) + m2 (h3 – h10) + m3 (h5 – h8) = 210 (Q1 + Q2 + Q3)
So, Work done by compressor C1 = me1 (h2 – h1)
Work done by compressor C2 = me2 (h4 – h3)
Work done by compressor C3 = me3 (h6 – h5)
Total work = me1 (h2 – h1) + me2 (h4 – h3) + me3 (h6 – h5)
C.O.P. = Total refrigeration effect / Total work done
= m1 (h1 – h12) + m2 (h3 – h10) + m3 (h5 – h8) / me1 (h2 – h1) + me2 (h4 – h3) + me3 (h6 – h5).

13. What is the value of enthalpy when refrigerant enters the second compressor, i.e., point 4?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q13
a) m1 h2 + m2 h3 / (m1 + m2)
b) m1 h11 + m2 h8 + m3 h5 / (m1 – m2 + m3)
c) m1 h2 + m2 h1 / (m1 + m2)
d) m1 h5 + m2 h5 + m3 h4 / (m1 + m2 + m3)
View Answer

Answer: a
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h1 – h12
m2 = 210 Q2 / h2 – h11
m3 = 210 Q3 / h6 – h10
At point 4, mass of refrigerant coming from evaporator 1 and 2 is converging.
So, (m1 + m2) h4 = m1 h2 + m2 h3
h4 = m1 h2 + m2 h3 / (m1 + m2).

14. What is the value of enthalpy when refrigerant enters the third compressor, i.e., point 7?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q13
a) m1 h2 + m2 h3 / (m1 + m2)
b) m1 h11 + m2 h8 + m3 h5 / (m1 – m2 + m3)
c) (m1 + m2) h5 + m3 h6 / (m1 + m2 + m3)
d) m1 h5 + m2 h5 + m3 h4 / (m1 + m2 + m3)
View Answer

Answer: c
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3.
Where, m1 = 210 Q1 / h1 – h12
m2 = 210 Q2 / h2 – h11
m3 = 210 Q3 / h6 – h10
At point 4, mass of refrigerant coming from evaporator 1 and 2 is converging.
So, (m1 + m2 + m3) h7 = (m1 + m2) h5 + m3 h6
h7 = (m1 + m2) h5 + m3 h6 / (m1 + m2 + m3).

15. What is the power required for the following arrangement?
refrigeration-questions-answers-multiple-evaporators-compressor-system-2-q13
a) m1 (h2 – h11) + (m1 + m2) (h5 – h8) + (m1 + m2 + m3) (h8 – h7) / 60
b) m1 (h2 – h1) + (m1 + m2) (h5 – h4) + (m1 + m2 + m3) (h8 – h7) / 60
c) m1 (h2 – h1) + (m2 + m3) (h5 – h4) + (m1 + m2 + m3) (h8 – h7) / 60
d) m1 h5 + m2 h5 + m3 h4 / (m1 + m2 + m3)
View Answer

Answer: b
Explanation: Let, mass m1, m2 and m3 be the mass of refrigerant circulated through evaporators EP1, EP2 and EP3
So, Power required to run compressor C1 = m1 (h2 – h1) / 60
Power required to run compressor C2 = (m1 + m2) (h5 – h4) / 60
Power required to run compressor C3 = (m1 + m2 + m3) (h8 – h7) / 60
Total power required to run the system will be summation of power required to run each compressor.
Total power required to run the system = m1 (h2 – h1) + (m1 + m2) (h5 – h4) + (m1 + m2 + m3) (h8 – h7) / 60.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter