BackAn ideal refrigerator utilizes a Carnot cycle operating between 0℃ and 25℃. To turn 10 kg of liquid water at 0℃ into 10 kg of ice at 0℃, (a) how much heat is exhausted into the room and (b) how much energy must be supplied to the refrigerator?
According to the second law of thermodynamics, which of the following actions will increase the maximum possible efficiency of a heat engine operating between two thermal reservoirs?
A typical coal-fired power plant burns 300 metric tons of coal every hour to generate 750 MW of electricity. 1 metric ton = 1000 kg. The density of coal is 1500 kg/m³ and its heat of combustion is 28 MJ/kg. Assume that all heat is transferred from the fuel to the boiler and that all the work done in spinning the turbine is transformed into electric energy. Suppose the coal is piled up in a 10 m ✕ 10 m room. How tall must the pile be to operate the plant for one day?
A certain power plant puts out 680 MW of electric power. Estimate the heat discharged per second, assuming that the plant has an efficiency of 32%.
A heat engine absorbs of heat from a high-temperature reservoir and expels of heat to a low-temperature reservoir in each cycle. What is the approximate efficiency of the heat engine?
FIGURE P21.46 shows a Carnot heat engine driving a Carnot refrigerator. Determine Q2, Q3 and Q4.
A Carnot refrigerator is operated between two heat reservoirs at temperatures of K and K. If in each cycle the refrigerator receives J of heat energy from the reservoir at K, how many joules of heat energy does it deliver to the reservoir at K?
A four-cylinder gasoline engine has an efficiency of 0.22 and delivers 180 J of work per cycle per cylinder. If the engine runs at 25 cycles per second (1500 rpm), determine the total heat input per second from the gasoline.
A heat engine uses a tank of ice water as a cold reservoir. The engine takes in 8 kJ of heat from the hot reservoir, and the heat expelled melts 18g of ice in the tank. How much work does this engine do?
Suppose a heat pump has a stationary bicycle attachment that allows you to provide the work instead of using an electrical wall outlet. If your heat pump has a coefficient of performance of 2.0 and you can cycle at a racing pace output of about 200 W for a half hour, how much heat can you provide?
A Carnot refrigerator operates between energy reservoirs at 0℃ and 250℃. A 2.4-cm-diameter, 50-cm-long copper bar connects the two energy reservoirs. At what rate, in W, must work be done on the refrigerator to remove heat from the cold reservoir at the same rate that it arrives through the copper bar?
A Carnot refrigerator is operated between two heat reservoirs at temperatures of K and K. If the refrigerator completes cycles each minute, what power input is required to operate it?
An aircraft engine takes in 9 kJ of heat and expels 6.4 kJ of heat each cycle. How much mechanical work does the engine do each cycle?
It has been suggested that a heat engine could be developed that made use of the temperature difference between water at the surface of the ocean and water several hundred meters deep. In the tropics, the temperatures may be 27°C and 4°C, respectively. What is the maximum efficiency such an engine could have?