Thermodynamics: An Engineering Approach
8th Edition
ISBN: 9780073398174
Author: Yunus A. Cengel Dr., Michael A. Boles
Publisher: McGraw-Hill Education
expand_more
expand_more
format_list_bulleted
Videos
Textbook Question
thumb_up100%
Chapter 11.10, Problem 31P
A room is kept at −5°C by a vapor-compression refrigeration cycle with R-134a as the refrigerant. Heat is rejected to cooling water that enters the condenser at 20°C at a rate of 0.13 kg/s and leaves at 28°C. The refrigerant enters the condenser at 1.2 MPa and 50°C and leaves as a saturated liquid. If the compressor consumes 1.9 kW of power, determine (a) the refrigeration load, in Btu/h and the COP, (b) the second-law efficiency of the refrigerator and the total exergy destruction in the cycle, and (c) the exergy destruction in the condenser. Take T0 = 20°C and cp,water = 4.18 kJ/kg·°C.
FIGURE P11–31
Expert Solution & Answer
Trending nowThis is a popular solution!
Students have asked these similar questions
Refrigerant 134a enters the condenser of a residential heat pump at 900 kPa and 40 degrees C at a rate of 0.02 kg/s and leaves at 900 kPa as a saturated liquid. If the compressor consumes 1.2 kW of power, determine the COP of the heat pump and the rate of absorption from the outside air.
A cooling system with a capacity of 10 tons of refrigeration operates at 210 KPA in the evaporator while in the condenser it is 850 KPA if the R-134a refrigerant is in a saturated state calculate the theoretical power required to operate the compressor.
A refrigerated room is kept at −18◦C by a vapor-compression cycle with R-134a as the refrigerant. Heat is rejected to cooling water that enters the condenser at 14◦C at a rate of 0.35 kg/s and leaves at 22◦C. The refrigerant enters the condenser at 1.2MPa and 50◦C and leaves at the same pressure subcooled by 5◦C. If the compressor consumes 5.5 kW of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load and the COP, (c) the second-law efficiency of the refrigerator and the total exergy destruction in the cycle, and (d) the exergy destruction in the condenser. Take specific heat of water to be 4.18 kJ/kg·◦C.
Chapter 11 Solutions
Thermodynamics: An Engineering Approach
Ch. 11.10 - Why is the reversed Carnot cycle executed within...Ch. 11.10 - Why do we study the reversed Carnot cycle even...Ch. 11.10 - 11–3 A steady-flow Carnot refrigeration cycle uses...Ch. 11.10 - Does the ideal vapor-compression refrigeration...Ch. 11.10 - Why is the throttling valve not replaced by an...Ch. 11.10 - It is proposed to use water instead of...Ch. 11.10 - In a refrigeration system, would you recommend...Ch. 11.10 - Does the area enclosed by the cycle on a T-s...Ch. 11.10 - Consider two vapor-compression refrigeration...Ch. 11.10 - The COP of vapor-compression refrigeration cycles...
Ch. 11.10 - An ice-making machine operates on the ideal...Ch. 11.10 - A 10-kW cooling load is to be served by operating...Ch. 11.10 - 11–13 An ideal vapor-compression refrigeration...Ch. 11.10 - 11–14 Consider a 300 kJ/min refrigeration system...Ch. 11.10 - 11–16 Repeat Prob. 11–14 assuming an isentropic...Ch. 11.10 - 11–17 Refrigerant-134a enters the compressor of a...Ch. 11.10 - A commercial refrigerator with refrigerant-134a as...Ch. 11.10 - 11–19 Refrigcrant-134a enters the compressor of a...Ch. 11.10 - A refrigerator uses refrigerant-134a as the...Ch. 11.10 - The manufacturer of an air conditioner claims a...Ch. 11.10 - Prob. 23PCh. 11.10 - How is the second-law efficiency of a refrigerator...Ch. 11.10 - Prob. 25PCh. 11.10 - Prob. 26PCh. 11.10 - Prob. 27PCh. 11.10 - 11–28 Bananas are to be cooled from 28°C to 12°C...Ch. 11.10 - A vapor-compression refrigeration system absorbs...Ch. 11.10 - A refrigerator operating on the vapor-compression...Ch. 11.10 - A room is kept at 5C by a vapor-compression...Ch. 11.10 - Prob. 32PCh. 11.10 - 11–33 A refrigeration system operates on the ideal...Ch. 11.10 - When selecting a refrigerant for a certain...Ch. 11.10 - Consider a refrigeration system using...Ch. 11.10 - A refrigerant-134a refrigerator is to maintain the...Ch. 11.10 - A refrigerator that operates on the ideal...Ch. 11.10 - A heat pump that operates on the ideal...Ch. 11.10 - Do you think a heat pump system will be more...Ch. 11.10 - What is a water-source heat pump? How does the COP...Ch. 11.10 - Prob. 42PCh. 11.10 - Refrigerant-134a enters the condenser of a...Ch. 11.10 - Prob. 45PCh. 11.10 - A heat pump using refrigerant-134a heats a house...Ch. 11.10 - How does the COP of a cascade refrigeration system...Ch. 11.10 - A certain application requires maintaining the...Ch. 11.10 - Consider a two-stage cascade refrigeration cycle...Ch. 11.10 - Can a vapor-compression refrigeration system with...Ch. 11.10 - Prob. 52PCh. 11.10 - Prob. 53PCh. 11.10 - Repeat Prob. 1156 for a flash chamber pressure of...Ch. 11.10 - Prob. 56PCh. 11.10 - Prob. 57PCh. 11.10 - 11–58 Consider a two-stage cascade refrigeration...Ch. 11.10 - Prob. 59PCh. 11.10 - A two-evaporator compression refrigeration system...Ch. 11.10 - A two-evaporator compression refrigeration system...Ch. 11.10 - Repeat Prob. 1163E if the 30 psia evaporator is to...Ch. 11.10 - How does the ideal gas refrigeration cycle differ...Ch. 11.10 - Devise a refrigeration cycle that works on the...Ch. 11.10 - How is the ideal gas refrigeration cycle modified...Ch. 11.10 - Prob. 66PCh. 11.10 - How do we achieve very low temperatures with gas...Ch. 11.10 - 11–68E Air enters the compressor of an ideal gas...Ch. 11.10 - Prob. 69PCh. 11.10 - Air enters the compressor of an ideal gas...Ch. 11.10 - Repeat Prob. 1173 for a compressor isentropic...Ch. 11.10 - Prob. 73PCh. 11.10 - Prob. 74PCh. 11.10 - Prob. 75PCh. 11.10 - A gas refrigeration system using air as the...Ch. 11.10 - An ideal gas refrigeration system with two stages...Ch. 11.10 - Prob. 78PCh. 11.10 - Prob. 79PCh. 11.10 - What are the advantages and disadvantages of...Ch. 11.10 - Prob. 81PCh. 11.10 - Prob. 82PCh. 11.10 - An absorption refrigeration system that receives...Ch. 11.10 - An absorption refrigeration system receives heat...Ch. 11.10 - Heat is supplied to an absorption refrigeration...Ch. 11.10 - Prob. 86PCh. 11.10 - Prob. 87PCh. 11.10 - Prob. 88PCh. 11.10 - Prob. 89PCh. 11.10 - Consider a circular copper wire formed by...Ch. 11.10 - An iron wire and a constantan wire are formed into...Ch. 11.10 - Prob. 92PCh. 11.10 - Prob. 93PCh. 11.10 - Prob. 94PCh. 11.10 - Prob. 95PCh. 11.10 - Prob. 96PCh. 11.10 - Prob. 97PCh. 11.10 - Prob. 98PCh. 11.10 - A thermoelectric cooler has a COP of 0.18, and the...Ch. 11.10 - Prob. 100PCh. 11.10 - Prob. 101PCh. 11.10 - Prob. 102PCh. 11.10 - Prob. 103RPCh. 11.10 - Prob. 104RPCh. 11.10 - Prob. 105RPCh. 11.10 - A heat pump that operates on the ideal...Ch. 11.10 - A large refrigeration plant is to be maintained at...Ch. 11.10 - Repeat Prob. 11112 assuming the compressor has an...Ch. 11.10 - A heat pump operates on the ideal...Ch. 11.10 - An air conditioner with refrigerant-134a as the...Ch. 11.10 - An air conditioner operates on the...Ch. 11.10 - Consider a two-stage compression refrigeration...Ch. 11.10 - A two-evaporator compression refrigeration system...Ch. 11.10 - Prob. 116RPCh. 11.10 - Prob. 117RPCh. 11.10 - Prob. 118RPCh. 11.10 - Consider a regenerative gas refrigeration cycle...Ch. 11.10 - Prob. 120RPCh. 11.10 - The refrigeration system of Fig. P11122 is another...Ch. 11.10 - Repeat Prob. 11122 if the heat exchanger provides...Ch. 11.10 - An ideal gas refrigeration system with three...Ch. 11.10 - Derive a relation for the COP of the two-stage...Ch. 11.10 - Prob. 129FEPCh. 11.10 - Prob. 130FEPCh. 11.10 - Prob. 131FEPCh. 11.10 - Prob. 132FEPCh. 11.10 - An ideal vapor-compression refrigeration cycle...Ch. 11.10 - Prob. 134FEPCh. 11.10 - An ideal gas refrigeration cycle using air as the...Ch. 11.10 - Prob. 136FEPCh. 11.10 - Prob. 137FEPCh. 11.10 - Prob. 138FEP
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- A heat pump with refrigerant-134a as the working fluid is used to keep a space at 25°C byabsorbing heat from geothermal water that enters the evaporator at 50°C at a rate of0.065 kg/s and leaves at 40°C. Refrigerant enters the evaporator at 20°C with a quality of15 percent and leaves at the same pressure as saturated vapor. If the compressorconsumes 1.2 kW of power, determine (a) the mass flow rate of the refrigerant, (b) therate of heat supply to the space, (c) the COP, and (d) the minimum power input to thecompressor for the same rate of heat supply.arrow_forward2- 750 LPa 55 Condumsur Expusion valve Corpressor Evaparatx Refrigerant-134a enters the condenser of a residential heat pump at 800 kPa and 550C at a rate of 0.018 kg/s and leaves at 750 kPa subcooled by 3°C. The refrigerant enters the compressor at 200 kPa superheated by 4°C. Determine a-the isentropic efficiency of the compressor b-the rate heat supplied to the heated room c-the COP of the heat pumparrow_forwardRefrigerant-134a enters the compressor of a cooling system as superheated vapor at 0.18 MPa and 0°C with a flow rate of 0.15 kg/s. It exits the compressor at 0.8 MPa and 60°C. Post compression, the refrigerant is cooled in the condenser to 28°C and 1.4 MPa. Subsequently, it's throttled to 0.16 MPa. Neglecting any heat transfer and pressure drops in the pipelines between the components, represent the cycle on a T-s diagram concerning saturation lines. Calculate: (a) The rate of heat extraction from the cooling area and the energy input to the compressor. (b) The isentropic efficiency of the compressor. (c) The Coefficient of Performance (COP) of the cooling system.arrow_forward
- A heat pump with refrigerant-134a as the working fluid is used to keep a space at 25C by absorbing heat from geothermal water that enters the evaporator at 508C at a rate of 0.065 kg/s and leaves at 40C. The refrigerant enters the evaporator at 20C with a quality of 23 percent and leaves at the inlet pressure as saturated vapor. The refrigerant loses 300 W of heat to the surroundings as it flows through the compressor and the refrigerant leaves the compressor at 1.4 MPa at the same entropy as the inlet. Determine (a) the degrees of subcooling of the refrigerant in the condenser, (b) the mass flow rate of the refrigerant, (c) the heating load and the COP of the heat pump, and (d) the theoretical minimum power input to the compressor for the same heating load.arrow_forwardThermodynamicarrow_forwardA heat pump uses R-134a as the refrigerant. The refrigerant enters the adiabatic compressor as saturated vapor at 120 kPa and exits it (the compressor) at 800 kPa and 50°C. The refrigerant exits the condenser as saturated liquid at 800 kPa. Then, the refrigerant flows through an adiabatic expansion valve, reducing the pressure back to the evaporator pressure of 120 kPa. The compressor power is 1.25 kW. a) Calculate the mass flow rate of the refrigerant (R-134a) in kg/s or g/s. b) Calculate the heat power delivered from the condenser in kW. c) Calculate the coefficient of performance (COP) of the heat pump, COP_HP.d) Calculate the refrigerant’s vapor quality entering the evaporator.arrow_forward
- A- A heat pump using refrigerant-134a heats house by using underground water at 8 C° as the heat source. The house is losing heat at a rate of 60000 kJ/h.-The refrigerant enters the compressor at 280 kPa and 0 C°, and it leaves at 1 Mpa and 60 C°. The refrigerant exits the condenser at 30 G. Determine: a- The power input to the heat pump. b- The rate ofheat absorption from the water. c- The increase in electric power input if an electric resistance heater is used instead of a heat pump.arrow_forward1) Refrigerant-134a enters the condenser at 200 kPa and 10°C and it leaves at 200 kPa with a quality of 45 percent in a heat pump. The load of heat pump is 700 W and COP of the heat pump is 3.5, determine a- The rate of heat gains from the environment ( b- The minimum compressor work c- The mass flow rate of the refrigerantarrow_forwardA geothermal heat pump running a simple heat pump cycle uses R-134a as the refrigerant and sources thermal energy from well water. The well water enters the evaporator at 13°C and exits at 7°C, with negligible pressure drop. On the refrigerant side, the evaporator operates isobarically at 320 kPa and the refrigerant exits the evaporator at 10°C. The refrigerant is compressed to 1200 kPa through the compressor, which has an isentropic efficiency of 90%. In the condenser, air absorbs energy from the refrigerant at a rate of 4.5 tons (1 ton = 211 kJ/min) as its temperature increases from 22°C at the condenser inlet to 42°C at the condenser outlet. The condenser operates isobarically, and the refrigerant exits the condenser at 20°C. Calculate the input power to the compressor and the COP of the heat pump.arrow_forward
- For a 10-ton-capacity refrigeration system, the pressure of refrigerant in the evaporator is 210 kPa, whereas in the condenser it is 800 kPa. If R-314a is used under saturated conditions, calculate the theoretical power required to operate the compressor.arrow_forwardQuestion 3 In a vapour-compression refrigeration system, refrigerant - 134a enters the compressor superheated at 200 kPa and - 5 °C. The refrigerant enters the condenser at 1.4 MPa and 75 °C, and exits at 1.4 MPa as a saturated liquid. There is no significant heat transfer between the compressor and its surroundings, and the refrigerant passes through the evaporator with a negligible change in pressure. If the refrigerating capacity is 105 kW, represent the cycle on a T-s diagram and determine: a) the mass flow rate of the refrigerant in kg/s, b) the power input to the compressor in kW, c) the coefficient of performance, and (2) d) the isentropic compressor efficiencyarrow_forwardFor a 10-ton-capacity refrigeration system, the pressure of refrigerant in the evaporator is 210 kPa, whereas in the condenser it is 750 kPa. If ammonia (R-717) is used under saturated conditions, calculate the theoretical power required to operate the compressor.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Refrigeration and Air Conditioning Technology (Mi...Mechanical EngineeringISBN:9781305578296Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill JohnsonPublisher:Cengage Learning
Refrigeration and Air Conditioning Technology (Mi...
Mechanical Engineering
ISBN:9781305578296
Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson
Publisher:Cengage Learning
The Refrigeration Cycle Explained - The Four Major Components; Author: HVAC Know It All;https://www.youtube.com/watch?v=zfciSvOZDUY;License: Standard YouTube License, CC-BY