In a refrigerator, R-134a enters the evaporator (the cold heat exchanger) at –17°c , x= 25% and leaves at –170c, x = 1. The COP of the refrigerator is 2.3 and the mass flow rate is 0.006 kg/s. Find the net work input W to the cycle and the total heat rejection rate Q# to the surroundings? (You may need to do interpolation between the temperatures –16°C and – 18°C) |
In a refrigerator, R-134a enters the evaporator (the cold heat exchanger) at –17°c , x= 25% and leaves at –170c, x = 1. The COP of the refrigerator is 2.3 and the mass flow rate is 0.006 kg/s. Find the net work input W to the cycle and the total heat rejection rate Q# to the surroundings? (You may need to do interpolation between the temperatures –16°C and – 18°C) |
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
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Please state assumptions and tables.
![### Refrigeration Cycle Problem
#### Problem Statement:
In a refrigerator, Refrigerant-134a (R-134a) enters the evaporator (the cold heat exchanger) at \(-17^\circ C\), with a quality \(x = 25\%\) and leaves at \(-17^\circ C\), with a quality \(x = 1\). The Coefficient of Performance (COP) of the refrigerator is 2.3 and the mass flow rate is 0.006 kg/s. Find the net work input \(\dot{W}\) to the cycle and the total heat rejection rate \(\dot{Q}_H\) to the surroundings. (You may need to do interpolation between the temperatures \(-16^\circ C\) and \(-18^\circ C\)).
#### Explanation:
- **State 1 (Entering Evaporator):**
- Temperature (\(T_1\)): \(-17^\circ C\)
- Quality (\(x_1\)): 0.25 (25%)
- **State 2 (Leaving Evaporator):**
- Temperature (\(T_2\)): \(-17^\circ C\)
- Quality (\(x_2\)): 1 (100%)
#### Given Data:
- Coefficient of Performance (COP): 2.3
- Mass Flow Rate (\(\dot{m}\)): 0.006 kg/s
#### Objectives:
1. Net Work Input (\(\dot{W}\))
2. Total Heat Rejection Rate (\(\dot{Q}_H\))
#### Methodology:
To solve this problem, you would typically:
1. Use property tables or software to find the enthalpy values for R-134a at the given temperatures and qualities.
2. Apply the definition of COP for the refrigerator (\(COP_{refrigerator} = \frac{\dot{Q}_L}{\dot{W}}\)).
3. Determine the work input and heat transfer rates using energy balance equations.
(Here, interpolation might be required to find precise values for the enthalpies at \(-17^\circ C\)).
Note: As detailed numerical interpolation and property values are beyond the scope of this transcription, you should consult R-134a refrigerant tables for further calculation steps.
### Detailed Explanations and Diagrams
For comprehensive understanding and step-by-step calculations, students are encouraged to refer to their](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F85fca7bf-232e-4519-a24a-484951e6fadb%2Fb05749d3-74a2-42d5-93ea-4faa4ea9ec69%2F027xa09.png&w=3840&q=75)
Transcribed Image Text:### Refrigeration Cycle Problem
#### Problem Statement:
In a refrigerator, Refrigerant-134a (R-134a) enters the evaporator (the cold heat exchanger) at \(-17^\circ C\), with a quality \(x = 25\%\) and leaves at \(-17^\circ C\), with a quality \(x = 1\). The Coefficient of Performance (COP) of the refrigerator is 2.3 and the mass flow rate is 0.006 kg/s. Find the net work input \(\dot{W}\) to the cycle and the total heat rejection rate \(\dot{Q}_H\) to the surroundings. (You may need to do interpolation between the temperatures \(-16^\circ C\) and \(-18^\circ C\)).
#### Explanation:
- **State 1 (Entering Evaporator):**
- Temperature (\(T_1\)): \(-17^\circ C\)
- Quality (\(x_1\)): 0.25 (25%)
- **State 2 (Leaving Evaporator):**
- Temperature (\(T_2\)): \(-17^\circ C\)
- Quality (\(x_2\)): 1 (100%)
#### Given Data:
- Coefficient of Performance (COP): 2.3
- Mass Flow Rate (\(\dot{m}\)): 0.006 kg/s
#### Objectives:
1. Net Work Input (\(\dot{W}\))
2. Total Heat Rejection Rate (\(\dot{Q}_H\))
#### Methodology:
To solve this problem, you would typically:
1. Use property tables or software to find the enthalpy values for R-134a at the given temperatures and qualities.
2. Apply the definition of COP for the refrigerator (\(COP_{refrigerator} = \frac{\dot{Q}_L}{\dot{W}}\)).
3. Determine the work input and heat transfer rates using energy balance equations.
(Here, interpolation might be required to find precise values for the enthalpies at \(-17^\circ C\)).
Note: As detailed numerical interpolation and property values are beyond the scope of this transcription, you should consult R-134a refrigerant tables for further calculation steps.
### Detailed Explanations and Diagrams
For comprehensive understanding and step-by-step calculations, students are encouraged to refer to their
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