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# a) An engine operates on 90 degrees celsius geothermal water. It exhausts to a 20 degree celsius stream. What is its maximum percentage efficiency?

a) An engine operates on 90 degrees celsius geothermal water. It exhausts to a 20 degree celsius stream. What is its maximum percentage efficiency?
b) A carnot engine operates between reservoirs at 20 and 600 degrees celsius. If 10 kW of power is produced, find the rejected heat rate.
c) A carnot refrigeration cycle is used to estimate the energy requirement in an attempt to reduce the temperature of a specimen to absolute zero. Suppose that we wish to remove 0.05 J or energy from the specimen when it is at 2*10^(-6) K. How much work is necessary if the high temperature reservoir is at 20 degrees celsius?
d) Steam at a quality of 90%, is expanded in a cylinder at a constant pressure of 800 kPa by adding 2000 kJ/kg of heat. Compute the entropy increase.
e) 3 kg/s of saturated steam at 100 degrees celsius undergoes an isentropic expansion to 20 kPa, determine the work output.
f) Two kilograms of iron at 350 degrees celsius are chilled in a large volume of ice and water. Find the total entropy change.
g) Two kilograms of air are stored in a rigid volume of 2 cubic metres with the temperature initially at 350 degrees celsius. Heat is transferred from the air until the pressure reaches 120 kPa. Calculate the entropy change of the air.
h) Two hundred kilowatts are to be produced by a steam turbine. The outlet steam is to be saturated at 80 kPa and the steam entering will be at 500 degrees celsius. For an isentropic process, determine the mass flow rate of steam.

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