THERMODYNAMICS(SI UNITS,INTL.ED)EBOOK>I
8th Edition
ISBN: 9781307434316
Author: CENGEL
Publisher: INTER MCG
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Textbook Question
Chapter 6.11, Problem 39P
Determine the COP of a heat pump that supplies energy to a house at a rate of 8000 kJ/h for each kW of electric power it draws. Also, determine the rate of energy absorption from the outdoor air.
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If a house needs a minimum heat transfer rate of 75 kJ/h (i.e., 75 kJ of heat needs to be transferred into the house during one hour) to maintain a pleasant indoor temperature. If one wants to use a heat pump with a COP of 5.55 to fulfill this heat transfer rate, what is the corresponding electricity (in kWh) consumption to run such a heat pump for one hour?
A heat pump with a COP of 3.2 is used to heat a perfectly sealed house (no air leaks). The entire mass within the house (air, furniture, etc.) is equivalent to 1200 kg of air. When running, the heat pump consumes electric power at a rate of 5 kW. The temperature of the house was 7°C when the heat pump was turned on. If heat transfer through the envelope of the house (walls, roof, etc.) is negligible, the length of time the heat pump must run to raise the temperature of the entire contents of the house to 22°C is (a) 13.5 min (b) 43.1 min (c) 138 min (d) 18.8 min (e) 808 min
An inventor claims to have a solar powered heat pump that receives energy as heat from the sun at the rate of 10 kW and extracts energy as heat from the environment at the rate of 7 kW. This system does not require any shaft or electrical power input. If you think this device is impossible, explain why using basic principles to support your argument. If you think it might be possible, what would be the steady-state rate of transfer of energy as heat to the house? (Assume TH = 20 Cand TL = -15 C).
Chapter 6 Solutions
THERMODYNAMICS(SI UNITS,INTL.ED)EBOOK>I
Ch. 6.11 - Describe an imaginary process that violates both...Ch. 6.11 - Describe an imaginary process that satisfies the...Ch. 6.11 - Describe an imaginary process that satisfies the...Ch. 6.11 - An experimentalist claims to have raised the...Ch. 6.11 - Prob. 5PCh. 6.11 - Consider the process of baking potatoes in a...Ch. 6.11 - What are the characteristics of all heat engines?Ch. 6.11 - What is the KelvinPlanck expression of the second...Ch. 6.11 - Is it possible for a heat engine to operate...Ch. 6.11 - Baseboard heaters are basically electric...
Ch. 6.11 - Does a heat engine that has a thermal efficiency...Ch. 6.11 - In the absence of any friction and other...Ch. 6.11 - Are the efficiencies of all the work-producing...Ch. 6.11 - Consider a pan of water being heated (a) by...Ch. 6.11 - Prob. 15PCh. 6.11 - Prob. 16PCh. 6.11 - A heat engine has a heat input of 3 104 Btu/h and...Ch. 6.11 - Prob. 18PCh. 6.11 - A 600-MW steam power plant, which is cooled by a...Ch. 6.11 - Prob. 20PCh. 6.11 - A heat engine with a thermal efficiency of 45...Ch. 6.11 - A steam power plant with a power output of 150 MW...Ch. 6.11 - An automobile engine consumes fuel at a rate of 22...Ch. 6.11 - Prob. 24PCh. 6.11 - Prob. 25PCh. 6.11 - A coal-burning steam power plant produces a net...Ch. 6.11 - An Ocean Thermal Energy Conversion (OTEC) power...Ch. 6.11 - What is the difference between a refrigerator and...Ch. 6.11 - Prob. 29PCh. 6.11 - In a refrigerator, heat is transferred from a...Ch. 6.11 - A heat pump is a device that absorbs energy from...Ch. 6.11 - Define the coefficient of performance of a...Ch. 6.11 - Define the coefficient of performance of a heat...Ch. 6.11 - Prob. 34PCh. 6.11 - A refrigerator has a COP of 1.5. That is, the...Ch. 6.11 - What is the Clausius expression of the second law...Ch. 6.11 - Show that the KelvinPlanck and the Clausius...Ch. 6.11 - Prob. 38PCh. 6.11 - Determine the COP of a heat pump that supplies...Ch. 6.11 - Prob. 40PCh. 6.11 - Prob. 41PCh. 6.11 - 6–42 An air conditioner removes heat steadily from...Ch. 6.11 - 6–43 A food department is kept at –12°C by a...Ch. 6.11 - A household refrigerator that has a power input of...Ch. 6.11 - When a man returns to his well-sealed house on a...Ch. 6.11 - Prob. 47PCh. 6.11 - Prob. 48PCh. 6.11 - 6–49 A heat pump is used to maintain a house at a...Ch. 6.11 - Prob. 50PCh. 6.11 - A household refrigerator runs one-fourth of the...Ch. 6.11 - Prob. 52PCh. 6.11 - Consider an office room that is being cooled...Ch. 6.11 - Prob. 54PCh. 6.11 - Refrigerant-134a enters the condenser of a...Ch. 6.11 - An inventor claims to have developed a resistance...Ch. 6.11 - Prob. 57PCh. 6.11 - A cold canned drink is left in a warmer room where...Ch. 6.11 - A block slides down an inclined plane with...Ch. 6.11 - Prob. 60PCh. 6.11 - Show that processes that use work for mixing are...Ch. 6.11 - Why does a nonquasi-equilibrium compression...Ch. 6.11 - Prob. 63PCh. 6.11 - Prob. 64PCh. 6.11 - Prob. 65PCh. 6.11 - Why are engineers interested in reversible...Ch. 6.11 - What are the four processes that make up the...Ch. 6.11 - Prob. 68PCh. 6.11 - Prob. 69PCh. 6.11 - Prob. 70PCh. 6.11 - Somebody claims to have developed a new reversible...Ch. 6.11 - Is there any way to increase the efficiency of a...Ch. 6.11 - Consider two actual power plants operating with...Ch. 6.11 - Prob. 74PCh. 6.11 - Prob. 75PCh. 6.11 - 6–76 A Carnot heat engine receives 650 kJ of heat...Ch. 6.11 - A Carnot heat engine operates between a source at...Ch. 6.11 - A heat engine operates between a source at 477C...Ch. 6.11 - Prob. 80PCh. 6.11 - Prob. 81PCh. 6.11 - In tropical climates, the water near the surface...Ch. 6.11 - 6–83 A well-established way of power generation...Ch. 6.11 - Prob. 84PCh. 6.11 - Prob. 85PCh. 6.11 - How can we increase the COP of a Carnot...Ch. 6.11 - In an effort to conserve energy in a heat-engine...Ch. 6.11 - Prob. 88PCh. 6.11 - Prob. 89PCh. 6.11 - 6–90 During an experiment conducted in a room at...Ch. 6.11 - Prob. 91PCh. 6.11 - An air-conditioning system operating on the...Ch. 6.11 - Prob. 93PCh. 6.11 - Prob. 94PCh. 6.11 - Prob. 95PCh. 6.11 - Prob. 96PCh. 6.11 - 6–97 A heat pump is used to maintain a house at...Ch. 6.11 - Prob. 98PCh. 6.11 - Prob. 99PCh. 6.11 - Prob. 100PCh. 6.11 - A commercial refrigerator with refrigerant-134a as...Ch. 6.11 - Prob. 102PCh. 6.11 - A heat pump is to be used for heating a house in...Ch. 6.11 - A Carnot heat pump is to be used to heat a house...Ch. 6.11 - A Carnot heat engine receives heat from a...Ch. 6.11 - Prob. 106PCh. 6.11 - Prob. 107PCh. 6.11 - Prob. 108PCh. 6.11 - Derive an expression for the COP of a completely...Ch. 6.11 - Prob. 110PCh. 6.11 - Prob. 111PCh. 6.11 - Prob. 112PCh. 6.11 - Prob. 113PCh. 6.11 - Someone proposes that the entire...Ch. 6.11 - Prob. 115PCh. 6.11 - Prob. 116PCh. 6.11 - Prob. 117PCh. 6.11 - It is often stated that the refrigerator door...Ch. 6.11 - Prob. 119RPCh. 6.11 - A Carnot heat pump is used to heat and maintain a...Ch. 6.11 - Prob. 121RPCh. 6.11 - Prob. 122RPCh. 6.11 - A refrigeration system uses a water-cooled...Ch. 6.11 - A heat pump with a COP of 2.8 is used to heat an...Ch. 6.11 - Prob. 125RPCh. 6.11 - Consider a Carnot refrigeration cycle executed in...Ch. 6.11 - Consider two Carnot heat engines operating in...Ch. 6.11 - Prob. 129RPCh. 6.11 - A heat engine operates between two reservoirs at...Ch. 6.11 - Prob. 132RPCh. 6.11 - An old gas turbine has an efficiency of 21 percent...Ch. 6.11 - Prob. 134RPCh. 6.11 - Prob. 135RPCh. 6.11 - Prob. 136RPCh. 6.11 - Prob. 137RPCh. 6.11 - Prob. 138RPCh. 6.11 - Prob. 139RPCh. 6.11 - A refrigeration system is to cool bread loaves...Ch. 6.11 - The drinking water needs of a production facility...Ch. 6.11 - Prob. 143RPCh. 6.11 - Prob. 145RPCh. 6.11 - Prob. 146RPCh. 6.11 - Prob. 147RPCh. 6.11 - Prob. 148RPCh. 6.11 - A heat pump with refrigerant-134a as the working...Ch. 6.11 - Prob. 150RPCh. 6.11 - Prob. 151RPCh. 6.11 - Prob. 153RPCh. 6.11 - Prob. 154RPCh. 6.11 - Prob. 155RPCh. 6.11 - A 2.4-m-high 200-m2 house is maintained at 22C by...Ch. 6.11 - Prob. 157FEPCh. 6.11 - Prob. 158FEPCh. 6.11 - A heat pump is absorbing heat from the cold...Ch. 6.11 - A heat engine cycle is executed with steam in the...Ch. 6.11 - A heat engine receives heat from a source at 1000C...Ch. 6.11 - Prob. 162FEPCh. 6.11 - A refrigeration cycle is executed with R-134a...Ch. 6.11 - A heat pump with a COP of 3.2 is used to heat a...Ch. 6.11 - A heat engine cycle is executed with steam in the...Ch. 6.11 - An air-conditioning system operating on the...Ch. 6.11 - Prob. 167FEPCh. 6.11 - Two Carnot heat engines are operating in series...Ch. 6.11 - Consider a Carnot refrigerator and a Carnot heat...Ch. 6.11 - A typical new household refrigerator consumes...Ch. 6.11 - A window air conditioner that consumes 1 kW of...
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