Explanation Given: Efficiency of the electric furnace ( η electric ) is 1.0 . Efficiency of the gas furnace ( η gas ) is 0.87 . Efficiency of the oil furnace ( η oil ) is 0.87 . Unit cost of energy supplied for the electric furnace is $ 0.12 / kWh . Unit cost of energy supplied for the gas furnace is $ 1.24 / therm . Unit cost of energy supplied for the oil furnace is $ 2.3 / gal . Calculation: Calculate the unit cost of useful energy for the electric furnace. Unit cost of useful energy = Unit cost of energy supplied for the electric furnace η electric = $ 0.12 / kWh 1.0 = $ 0.12 / kWh 1.0 ( 1 kWh 3600 kJ ) = $ 33.3 × 10 − 6 / kJ Calculate the unit cost of useful energy for the gas furnace. Unit cost of useful energy = Unit cost of energy supplied for the gas furnace η gas = $ 1

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ISBN: 9780078027680

Author: Yunus A. Cengel Dr., Robert H. Turner, John M. Cimbala

Publisher: McGraw-Hill Education

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Chapter 3, Problem 76RQ

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The heating system with the lowest energy cost.

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Chapter 3, Problem 75RQ

Chapter 3, Problem 77RQ

Chapter 3 Solutions

Fundamentals of Thermal-Fluid Sciences

Ch. 3 - Prob. 1P Ch. 3 - List the forms of energy that contribute to the...Ch. 3 - How are heat, internal energy, and thermal energy...Ch. 3 - Prob. 4P Ch. 3 - Natural gas, which is mostly methane CH4, is a...Ch. 3 - Portable electric heaters are commonly used to...Ch. 3 - Prob. 7P Ch. 3 - Calculate the total kinetic energy, in Btu, of an...Ch. 3 - Calculate the total potential energy, in Btu, of...Ch. 3 - A person gets into an elevator at the lobby level...

Ch. 3 - Electric power is to be generated by installing a...Ch. 3 - Prob. 12P Ch. 3 - Prob. 13P Ch. 3 - Prob. 14P Ch. 3 - A river flowing steadily at a rate of 175 m3/s is...Ch. 3 - Consider a river flowing toward a lake at an...Ch. 3 - Prob. 17P Ch. 3 - Prob. 18P Ch. 3 - A gas in a piston-cylinder device is compressed,...Ch. 3 - A room is heated by an iron that is left plugged...Ch. 3 - A room is heated as a result of solar radiation...Ch. 3 - An insulated room is heated by burning candles. Is...Ch. 3 - Prob. 23P Ch. 3 - A model aircraft internal-combustion engine...Ch. 3 - Lifting a weight to a height of 20 m takes 20 s...Ch. 3 - A construction crane lifts a prestressed concrete...Ch. 3 - A man weighing 180 lbf is pushing a cart that...Ch. 3 - Prob. 28P Ch. 3 - Determine the energy required to accelerate a...Ch. 3 - Prob. 30P Ch. 3 - Prob. 31P Ch. 3 - Determine the work required to deflect a linear...Ch. 3 - Prob. 33P Ch. 3 - Prob. 34P Ch. 3 - Prob. 35P Ch. 3 - What are the different mechanisms for transferring...Ch. 3 - Prob. 37P Ch. 3 - Water is being heated in a closed pan on top of a...Ch. 3 - A vertical piston-cylinder device contains water...Ch. 3 - Prob. 40P Ch. 3 - A water pump increases the water pressure from 15...Ch. 3 - Prob. 42P Ch. 3 - A classroom that normally contains 40 people is to...Ch. 3 - Prob. 44P Ch. 3 - Consider a room that is initially at the outdoor...Ch. 3 - Prob. 46P Ch. 3 - The 60-W fan of a central heating system is to...Ch. 3 - The driving force for fluid flow is the pressure...Ch. 3 - Prob. 49P Ch. 3 - Prob. 50P Ch. 3 - How is the combined pump–motor efficiency of a...Ch. 3 - Define turbine efficiency, generator efficiency,...Ch. 3 - Prob. 53P Ch. 3 - Consider a 24-kW hooded electric open burner in an...Ch. 3 - Prob. 55P Ch. 3 - Prob. 56P Ch. 3 - The steam requirements of a manufacturing facility...Ch. 3 - Prob. 59P Ch. 3 - Prob. 60P Ch. 3 - Prob. 61P Ch. 3 - The water in a large lake is to be used to...Ch. 3 - Prob. 63P Ch. 3 - Prob. 64P Ch. 3 - Reconsider Prob. 3–64. Using an appropriate...Ch. 3 - Prob. 66P Ch. 3 - Prob. 67P Ch. 3 - Prob. 68P Ch. 3 - Prob. 69P Ch. 3 - Prob. 70P Ch. 3 - Prob. 71P Ch. 3 - Prob. 72P Ch. 3 - Prob. 73RQ Ch. 3 - Prob. 74RQ Ch. 3 - Prob. 75RQ Ch. 3 - Prob. 76RQ Ch. 3 - Prob. 77RQ Ch. 3 - Prob. 78RQ Ch. 3 - Prob. 79RQ Ch. 3 - A man weighing 180 lbf pushes a block weighing 100...Ch. 3 - Prob. 81RQ Ch. 3 - Prob. 82RQ Ch. 3 - Prob. 83RQ Ch. 3 - Windmills slow the air and cause it to fill a...Ch. 3 - In a hydroelectric power plant, 65 m3/s of water...Ch. 3 - Prob. 86RQ Ch. 3 - The pump of a water distribution system is powered...

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