4.5 The carnot cycle  (Page 4/7)

To increase the efficiency of a Carnot engine, should the temperature of the hot reservoir be raised or lowered? What about the cold reservoir?

How could you design a Carnot engine with $100\text{\%}$ efficiency?

What type of processes occur in a Carnot cycle?

The temperature of the cold and hot reservoirs between which a Carnot refrigerator operates are $\mathrm{-73}\text{°}\text{C}$ and $270\text{°C}$ , respectively. Which is its coefficient of performance?

Suppose a Carnot refrigerator operates between $T_{\text{c}}\text{and}{T}_{\text{h}}.$ Calculate the amount of work required to extract 1.0 J of heat from the cold reservoir if (a) $T_{\text{c}}=7\text{°}\text{C}$ , $T_{\text{h}}=27\text{°}\text{C}$ ; (b) $T_{\text{c}}=\mathrm{-73}\text{°}\text{C}$ , $T_{\text{h}}=27\text{°}\text{C;}$ (c) $T_{\text{c}}=\mathrm{-173}\text{°}\text{C}$ , $T_{\text{h}}=27\text{°}\text{C}$ ; and (d) $T_{\text{c}}=\mathrm{-273}\text{°}\text{C}$ , $T_{\text{h}}=27\text{°}\text{C}$ .

A Carnot engine operates between reservoirs at 600 and 300 K. If the engine absorbs 100 J per cycle at the hot reservoir, what is its work output per cycle?

A 500-W motor operates a Carnot refrigerator between $\mathrm{-5}\text{°}\text{C}$ and $30\text{°C}$ . (a) What is the amount of heat per second extracted from the inside of the refrigerator? (b) How much heat is exhausted to the outside air per second?

Sketch a Carnot cycle on a temperature-volume diagram.

A Carnot heat pump operates between $0\text{°C}$ and $20\text{°C}$ . How much heat is exhausted into the interior of a house for every 1.0 J of work done by the pump?

An engine operating between heat reservoirs at $20\text{°}\text{C}$ and $200\text{°}\text{C}$ extracts 1000 J per cycle from the hot reservoir. (a) What is the maximum possible work that engine can do per cycle? (b) For this maximum work, how much heat is exhausted to the cold reservoir per cycle?

Suppose a Carnot engine can be operated between two reservoirs as either a heat engine or a refrigerator. How is the coefficient of performance of the refrigerator related to the efficiency of the heat engine?

A Carnot engine is used to measure the temperature of a heat reservoir. The engine operates between the heat reservoir and a reservoir consisting of water at its triple point. (a) If 400 J per cycle are removed from the heat reservoir while 200 J per cycle are deposited in the triple-point reservoir, what is the temperature of the heat reservoir? (b) If 400 J per cycle are removed from the triple-point reservoir while 200 J per cycle are deposited in the heat reservoir, what is the temperature of the heat reservoir?

What is the minimum work required of a refrigerator if it is to extract 50 J per cycle from the inside of a freezer at $\mathrm{-10}\text{°C}$ and exhaust heat to the air at $25\text{°C}$ ?