EBK THERMODYNAMICS: AN ENGINEERING APPR
8th Edition
ISBN: 9780100257054
Author: CENGEL
Publisher: YUZU
expand_more
expand_more
format_list_bulleted
Videos
Textbook Question
Chapter 11.10, Problem 119RP
Consider a regenerative gas refrigeration cycle using helium as the working fluid. Helium enters the compressor at 100 kPa and −10°C and is compressed to 300 kPa. Helium is then cooled to 20°C by water. It then enters the regenerator, where it is cooled further before it enters the turbine. Helium leaves the refrigerated space at −25°C and enters the regenerator. Assuming both the turbine and the compressor to be isentropic, determine (a) the temperature of the helium at the turbine inlet, (b) the coefficient of performance of the cycle, and (c) the net power input required for a mass flow rate of 0.45 kg/s.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Consider a gas refrigeration system with air as the working fluid. The pressure ratio is 5.5.
Air enters the compressor at 0°C. The high-pressure air is cooled to 35 °C by rejecting heat to the surroundings. The refrigerant leaves the turbine at -95°C and then it absorbs heat from the refrigerated space before entering the regenerator. The mass flow rate of air is 0.55 kg/s. Assuming isentropic efficiencies of 90% for both the compressor and the turbine, determine (a) the effectiveness of the regenerator, (b) the rate of heat removal from the refrigerated space, and (c) the COP of the cycle. Also, determine (d) the refrigeration load and the COP if this system operated on the simple gas refrigeration cycle. In this cycle, take the compressor and turbine inlet temperatures to be 0 and 35 °C, respectively, and use the same compressor and turbine efficiencies. Use constant specific heat for air at room temperature with Cp
= 1.005 kJ/kg K and k = 1.4.
A gas turbine uses two compression and two expansion stages, each stage having a pressure ratio of 4.
The working fluid is intercooled between the two compression stages and reheated between the two
expansion stages. Air enters the gas turbine at 100kPa and 17°C. The combustion chamber and reheat
stage each contribute 300kJ/kg of heat. A regenerator uses exhausted gases to increase the working
fluid temperature prior to the combustion chamber by 20°C.
Assume constant thermal properties of air evaluated at 300K during your solution. Assume all turbine
and compressor stages are isentropic.
Draw the T-s diagram based on the numbering convention in the schematic below.
Determine the system's thermal efficiency.
Determine the required air mass flow rate to obtain an output of 10MW.
26 REMEWS
REHEAT
JNTER.
Ti
C2
Come
REGEN.
Scannad wim Camirwner
A 5 ton refrigeration system operates on a vapor-compression refrigeration cycle with
refrigerant-134a as the working fluid. The refrigerant enters the compressor as a
saturated vapor at 360 kPa and is compressed to 1.6 MPa with a compressor outlet
temperature of 70°C. Also, it enters the throttling valve as a saturated liquid. Determine
the quality of the refrigerant at the end of the throttling process
isentropic efficiency of the compressor
determine the coefficient of performance
Draw the cycle on a T-s diagram
determine the
2
and determine the compressor input power
with respect to the saturation lines
[Note: A "ton" of refrigeration is a term used in the air conditioning industry. Historically,
it is the rate of cooling necessary to freeze one ton (2000 lbm) of water in 24 hours.
Using the "latent heat" of fusion, the mass and the time, this cooling rate works out to be
12,000 Btu/h = 3.517 kW.]
Chapter 11 Solutions
EBK THERMODYNAMICS: AN ENGINEERING APPR
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 gas refrigeration system using air as the working fluid has a pressure ratio of 4. Air enters the compressor at -7°C. The high-pressure air is cooled to 27°C by rejecting heat to the surroundings. It is further cooled to -15°C by regenerative cooling before it enters the turbine. Assuming both the turbine and the compressor to be isentropic and using constant specific heats at room temperature, determine (a) the lowest temperature that can be obtained by this cycle, (b) the coefficient of performance of the cycle, and (c) the mass flow rate of air for a refrigeration rate of 12 kW.arrow_forwardA 5 ton refrigeration system operates on a vapor-compression refrigeration cycle with refrigerant-134a as the working fluid. The refrigerant enters the compressor as a saturated vapor at 360 kPa and is compressed to 1.6 MPa with a compressor outlet temperature of 70°C. Also, it enters the throttling valve as a saturated liquid. Determine the quality of the refrigerant at the end of the throttling process ( determine the isentropic efficiency of the compressor determine the coefficient of performance ), and determine the compressor input power. Draw the cycle on a T-s diagram with respect to the saturation lines [Note: A "ton" of refrigeration is a term used in the air conditioning industry. Historically, it is the rate of cooling necessary to freeze one ton (2000 lbm) of water in 24 hours. Using the "latent heat" of fusion, the mass and the time, this cooling rate works out to be 12,000 Btu/h = 3.517 kW.]arrow_forwardConsider an ideal regenerative steam cycle with an open preheater. Steam enters the turbine at 15MPa and 600°C and is condensed in a pressure condenser 10kPa. Part of the steam is extracted from the turbine at 1.2MPa and enters the open preheater. Determine the fraction of steam extracted and the thermal efficiency of the cycle.arrow_forward
- A gas refrigeration system utilizing air as the working fluid possesses a pressure ratio of 3. The air is directed into the compressor at 5°C. The high- pressure air is then cooled down to 40°C by rejecting heat to the ambient environment. The refrigerant exits the turbine at -85°C and subsequently absorbs heat from the cooling area prior to its entry into the regenerator. The mass flow rate of air is 0.45 kg/s. Given that the isentropic efficiencies are 82 percent for the compressor and 87 percent for the turbine, and using constant specific heats at ambient temperature, find: ) The refrigeration load and the COP if this system functioned based on thesimple gas refrigeration cycle.Ensure that the same compressor inlet temperature is maintained as given, andthe turbine inlet temperature is kept constant as calculated, along withidentical compressor and turbine efficiencies.arrow_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_forwardConsider an actual vapor-compression refrigeration cycle. R-134a enters the compressor as superheated vapor at 0.18 MPa and -10°C at a rate of 0.055 kg/s, and it leaves at 1.2 MPa and 60°C. The refrigerant is cooled in the condenser to 42°C and 1.15 MPa, and it is throttled to 0.22 MPa. Determine the rate of heat addition to the evaporator, in kW.arrow_forward
- A gas refrigeration system utilizing air as the working fluid possesses a pressure ratio of 3. The air is directed into the compressor at 5°C. The high- pressure air is then cooled down to 40°C by rejecting heat to the ambient environment. The refrigerant exits the turbine at -85°C and subsequently absorbs heat from the cooling area prior to its entry into the regenerator. The mass flow rate of air is 0.45 kg/s. Given that the isentropic efficiencies are 82 percent for the compressor and 87 percent for the turbine, and using constant specific heats at ambient temperature, find: (a) The effectiveness of the regenerator. (b) The rate at which heat is extracted from the cooling area. (c) The Coefficient of Performance (COP) of the cycle.arrow_forwardA commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at –30°C by rejecting its waste heat to cooling water that enters the condenser at 18°C at a rate of 0.25 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 65°C and leaves at 42°C. The inlet state of the compressor is 60 kPa and –34°C and the compressor is estimated to gain a net heat of 450 W from the surroundings. Determine the theoretical maximum refrigeration load for the same power input to the compressor. Water 26°C ↑ 18°C 1.2 MPа 42°C 65°C Condenser Expansion Win valve Evaporator Compressor 60 kPa -34°Carrow_forwardSuperheated water vapor enters the turbine at 5Mpa and 4000C. The water leaves the condenser as saturated liquid at a pressure of 30kPa, and the turbine efficiency is 91%. The net power output of the cycle is 100MW. Determine the thermal efficiency.arrow_forward
- Steam at 2000 psia and 1000°F enters the high-pressure turbine of a reheat cycle and is expanded adiabatically and reversibly to 200 psia. The steam is then passed through the superheater, from where it exits at the 950°F temperature. The low-pressure turbine expands the steam reversibly and adiabatically to 1 psia. If 7 lbm/s of steam is used and the circulating pump is assumed to operate ideally, the power produced, the added heat rate, and the cycle efficiency are: a) 7049,76 hp ; 12124,5 Btu/s ; 42,2% b) 7400,77 hp ; 11553,7 Btu/s ; 45,1% c) 8350,08 hp ; 13089,6 Btu/s ; 49,8% d) 7944,76 hp ; 11834,2 Btu/s ; 47,6%arrow_forwardA heat pump using refrigerant-134a heats a house by using underground water at 8°C as the heat source. The house is losing heat at a rate of 60,000 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°C. Investigate the effect of varying the compressor isentropic efficiency over the range [60 to 100 percent]. Plot the power input to the compressor and the electric power saved by using a heat pump rather than electric resistance heating as functions of compressor efficiency and discuss the results.arrow_forward2. Refrigerant-134a enters the compressor of a refrigerator at 100 kPa and -20°C at a rate of 0.5 m³/min and leaves at 0.8 MPa. The isentropic efficiency of the compressor is 78 percent. The refrigerant enters the throttling valve at 0.75 MPa and 26°C and leaves the evaporator as saturated vapor at 26°C. Show the cycle on a T-s diagram with respect to saturation lines, and determine (a) the power input to the compressor, (b) the rate of heat removal from the refrigerated space, and (c) the pressure drop and rate of heat gain in the line between the evaporator and the compressor. Answers: (a) 2.40 kW, (b) 6.17 kW, (c) 1.73 kPa, 0.203 kWarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University Press
Mechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSON
Thermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEY
Mechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage Learning
Engineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY
Elements Of Electromagnetics
Mechanical Engineering
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Oxford University Press
Mechanics of Materials (10th Edition)
Mechanical Engineering
ISBN:9780134319650
Author:Russell C. Hibbeler
Publisher:PEARSON
Thermodynamics: An Engineering Approach
Mechanical Engineering
ISBN:9781259822674
Author:Yunus A. Cengel Dr., Michael A. Boles
Publisher:McGraw-Hill Education
Control Systems Engineering
Mechanical Engineering
ISBN:9781118170519
Author:Norman S. Nise
Publisher:WILEY
Mechanics of Materials (MindTap Course List)
Mechanical Engineering
ISBN:9781337093347
Author:Barry J. Goodno, James M. Gere
Publisher:Cengage Learning
Engineering Mechanics: Statics
Mechanical Engineering
ISBN:9781118807330
Author:James L. Meriam, L. G. Kraige, J. N. Bolton
Publisher:WILEY
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