Exam 21: Heat Engines and Refrigerators

An engine manufacturer makes the claim that the engine they have developed will,on each cycle,take 100 J of heat out of boiling water at 100°C,do mechanical work of 80 J,and exhaust 20 J of heat at 10°C.What,if anything,is wrong with this claim?

A coal-fired plant generates 600 MW of electric power.The plant uses 4.8 × 10⁶ kg of coal each day.The heat produced by the combustion of coal is 3.3 × 10⁷ J/kg.The steam that drives the turbines is at a temperature of 300°C,and the exhaust water is at 37°C. (a)What is the overall efficiency of the plant for generating electric power? (b)What is the maximum efficiency that this plant could possibly have using the same temperature extremes that it presently uses? (c)How much thermal energy is exhausted each day by this plant?

A Carnot engine operates between a high temperature reservoir at and a river with water at If it absorbs of heat each cycle,how much work per cycle does it perform?

A 2.00 kg piece of lead at 40.0°C is placed in a very large quantity of water at 10.0°C,and thermal equilibrium is eventually reached.Calculate the TOTAL change in entropy that occurs during this process.The specific heat of lead is 130 J/(kg ∙ K).