6-26 A coal-burning power plant produces 300 MW of power. The amount of coal consumed during a one -day period and
the rate of air owing through the furnace are to be determined.
Assumptions 1 The power plant operates steadily. 2 The kinetic and potential
7-170 The source and sink temperatures and the COP of a refrigerator are given. The total entropy change of the two
reservoirs is to be calculated and it is to be determined if this refrigerator satisfies the second law.
Assumptions The refrigerator
7-181 Refrigerant-134a is vaporized by air in the evaporator of an air-conditioner. For specified flow rates, the exit
temperature of air and the rate of entropy generation are to be determined for the cases of an insulated and uninsulated
5-55 Steam expands in a two-stage adiabatic turbine from a specied state to another state. Some steam is extracted at the
end of the first stage. The power output of the turbine is to be determined.
Assumptions 1 This is a steady-ow process since the