Thermodynamics: An Engineering Approach
9th Edition
ISBN: 9781259822674
Author: Yunus A. Cengel Dr., Michael A. Boles
Publisher: McGraw-Hill Education
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Chapter 8.8, Problem 112RP
A passive solar house that was losing heat to the outdoors at 5°C at an average rate of 50,000 kJ/h was maintained at 22°C at all times during a winter night for 10 h. The house was heated by 50 glass containers, each containing 20 L of water that was heated to 80°C during the day by absorbing solar energy. A thermostat-controlled 15-kW backup electric resistance heater turned on whenever necessary to keep the house at 22°C. Determine (a) how long the electric heating system was on that night, (b) the exergy destruction, and (c) the minimum work input required for that night, in kJ.
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Chapter 8 Solutions
Thermodynamics: An Engineering Approach
Ch. 8.8 - What final state will maximize the work output of...Ch. 8.8 - Is the exergy of a system different in different...Ch. 8.8 - Under what conditions does the reversible work...Ch. 8.8 - How does useful work differ from actual work? For...Ch. 8.8 - How does reversible work differ from useful work?Ch. 8.8 - Is a process during which no entropy is generated...Ch. 8.8 - Consider an environment of zero absolute pressure...Ch. 8.8 - It is well known that the actual work between the...Ch. 8.8 - Consider two geothermal wells whose energy...Ch. 8.8 - Consider two systems that are at the same pressure...
Ch. 8.8 - Prob. 11PCh. 8.8 - Does a power plant that has a higher thermal...Ch. 8.8 - Prob. 13PCh. 8.8 - Saturated steam is generated in a boiler by...Ch. 8.8 - One method of meeting the extra electric power...Ch. 8.8 - A heat engine that receives heat from a furnace at...Ch. 8.8 - Consider a thermal energy reservoir at 1500 K that...Ch. 8.8 - A heat engine receives heat from a source at 1100...Ch. 8.8 - A heat engine that rejects waste heat to a sink at...Ch. 8.8 - A geothermal power plant uses geothermal liquid...Ch. 8.8 - A house that is losing heat at a rate of 35,000...Ch. 8.8 - A freezer is maintained at 20F by removing heat...Ch. 8.8 - Prob. 24PCh. 8.8 - Prob. 25PCh. 8.8 - Prob. 26PCh. 8.8 - Can a system have a higher second-law efficiency...Ch. 8.8 - A mass of 8 kg of helium undergoes a process from...Ch. 8.8 - Which is a more valuable resource for work...Ch. 8.8 - Which has the capability to produce the most work...Ch. 8.8 - The radiator of a steam heating system has a...Ch. 8.8 - A well-insulated rigid tank contains 6 lbm of a...Ch. 8.8 - A pistoncylinder device contains 8 kg of...Ch. 8.8 - Prob. 35PCh. 8.8 - Prob. 36PCh. 8.8 - Prob. 37PCh. 8.8 - A pistoncylinder device initially contains 2 L of...Ch. 8.8 - A 0.8-m3 insulated rigid tank contains 1.54 kg of...Ch. 8.8 - An insulated pistoncylinder device initially...Ch. 8.8 - Prob. 41PCh. 8.8 - An insulated rigid tank is divided into two equal...Ch. 8.8 - A 50-kg iron block and a 20-kg copper block, both...Ch. 8.8 - Prob. 45PCh. 8.8 - Prob. 46PCh. 8.8 - Prob. 47PCh. 8.8 - A pistoncylinder device initially contains 1.4 kg...Ch. 8.8 - Prob. 49PCh. 8.8 - Prob. 50PCh. 8.8 - Prob. 51PCh. 8.8 - Air enters a nozzle steadily at 200 kPa and 65C...Ch. 8.8 - Prob. 54PCh. 8.8 - Prob. 55PCh. 8.8 - Argon gas enters an adiabatic compressor at 120...Ch. 8.8 - Prob. 57PCh. 8.8 - Prob. 58PCh. 8.8 - The adiabatic compressor of a refrigeration system...Ch. 8.8 - Refrigerant-134a at 140 kPa and 10C is compressed...Ch. 8.8 - Air enters a compressor at ambient conditions of...Ch. 8.8 - Combustion gases enter a gas turbine at 900C, 800...Ch. 8.8 - Steam enters a turbine at 9 MPa, 600C, and 60 m/s...Ch. 8.8 - Refrigerant-134a is condensed in a refrigeration...Ch. 8.8 - Prob. 66PCh. 8.8 - Refrigerant-22 absorbs heat from a cooled space at...Ch. 8.8 - Prob. 68PCh. 8.8 - Prob. 69PCh. 8.8 - Air enters a compressor at ambient conditions of...Ch. 8.8 - Hot combustion gases enter the nozzle of a...Ch. 8.8 - Prob. 72PCh. 8.8 - A 0.6-m3 rigid tank is filled with saturated...Ch. 8.8 - Prob. 74PCh. 8.8 - Prob. 75PCh. 8.8 - An insulated vertical pistoncylinder device...Ch. 8.8 - Liquid water at 200 kPa and 15C is heated in a...Ch. 8.8 - Prob. 78PCh. 8.8 - Prob. 79PCh. 8.8 - A well-insulated shell-and-tube heat exchanger is...Ch. 8.8 - Steam is to be condensed on the shell side of a...Ch. 8.8 - Prob. 82PCh. 8.8 - Prob. 83PCh. 8.8 - Prob. 84PCh. 8.8 - Prob. 85RPCh. 8.8 - Prob. 86RPCh. 8.8 - An aluminum pan has a flat bottom whose diameter...Ch. 8.8 - Prob. 88RPCh. 8.8 - Prob. 89RPCh. 8.8 - A well-insulated, thin-walled, counterflow heat...Ch. 8.8 - Prob. 92RPCh. 8.8 - Prob. 93RPCh. 8.8 - Prob. 94RPCh. 8.8 - Prob. 95RPCh. 8.8 - Nitrogen gas enters a diffuser at 100 kPa and 110C...Ch. 8.8 - Prob. 97RPCh. 8.8 - Steam enters an adiabatic nozzle at 3.5 MPa and...Ch. 8.8 - Prob. 99RPCh. 8.8 - A pistoncylinder device initially contains 8 ft3...Ch. 8.8 - An adiabatic turbine operates with air entering at...Ch. 8.8 - Steam at 7 MPa and 400C enters a two-stage...Ch. 8.8 - Prob. 103RPCh. 8.8 - Steam enters a two-stage adiabatic turbine at 8...Ch. 8.8 - Prob. 105RPCh. 8.8 - Prob. 106RPCh. 8.8 - Prob. 107RPCh. 8.8 - Prob. 108RPCh. 8.8 - Prob. 109RPCh. 8.8 - Prob. 111RPCh. 8.8 - A passive solar house that was losing heat to the...Ch. 8.8 - Prob. 113RPCh. 8.8 - A 4-L pressure cooker has an operating pressure of...Ch. 8.8 - Repeat Prob. 8114 if heat were supplied to the...Ch. 8.8 - Prob. 116RPCh. 8.8 - A rigid 50-L nitrogen cylinder is equipped with a...Ch. 8.8 - Prob. 118RPCh. 8.8 - Prob. 119RPCh. 8.8 - Prob. 120RPCh. 8.8 - Reconsider Prob. 8-120. The air stored in the tank...Ch. 8.8 - Prob. 122RPCh. 8.8 - Prob. 123RPCh. 8.8 - Prob. 124RPCh. 8.8 - Prob. 125RPCh. 8.8 - Prob. 126RPCh. 8.8 - Prob. 127RPCh. 8.8 - Water enters a pump at 100 kPa and 30C at a rate...Ch. 8.8 - Prob. 129RPCh. 8.8 - Prob. 130RPCh. 8.8 - Obtain a relation for the second-law efficiency of...Ch. 8.8 - Writing the first- and second-law relations and...Ch. 8.8 - Prob. 133RPCh. 8.8 - Keeping the limitations imposed by the second law...Ch. 8.8 - Prob. 135FEPCh. 8.8 - Prob. 136FEPCh. 8.8 - Prob. 137FEPCh. 8.8 - Prob. 138FEPCh. 8.8 - A furnace can supply heat steadily at 1300 K at a...Ch. 8.8 - A heat engine receives heat from a source at 1500...Ch. 8.8 - Air is throttled from 50C and 800 kPa to a...Ch. 8.8 - Prob. 142FEPCh. 8.8 - A 12-kg solid whose specific heat is 2.8 kJ/kgC is...
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- A passive solar house that is losing heat to the outdoors at 3C at an average rate of 50,000 kJ/h is maintained at 22C at all times during a winter night for 10 h. The house is to be heated by 50 glass containers, each containing 20 L of water that is heated to 80C during the day by absorbing solar energy. A thermostat-controlled 15 kW backup electric resistance heater turns on whenever necessary to keep the house at 22C. Determine how long the electric heating system was on that night and the amount of entropy generated during the night.arrow_forwardSuperheated steam enters the turbine of a steam power plant at 5 MPa and 450 ºC, and exits at 10 kPa. Determine the actual turbine work when the turbine isentropic efficiency is 90% and the mass flow rate of steam is 10 kg/s.arrow_forwardWhat is the minimum internal energy that steam can achieve as it is expanded adiabatically in a closed system from 1500 kPa and 320°C to 100 kPa?arrow_forward
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