23. The Second Law of Thermodynamics

A refrigerator has a coefficient of performance of 2.4. Each cycle, it takes in 3×10⁴ J of heat from the cold reservoir. How much is expelled to the hot reservoir?

A certain brand of freezer is advertised to use $730$ kWh of energy per year. What is the theoretical maximum amount of ice this freezer could make in an hour, starting with water at $20.0$°C?

A certain brand of freezer is advertised to use $730$ kWh of energy per year. Assuming the freezer operates for $5$ hours each day, how much power does it require while operating?

A refrigerator has a coefficient of performance of $2.25$, runs on an input of $135$ W of electrical power, and keeps its inside compartment at $5$°C. If you put a dozen $1.0$-L plastic bottles of water at $31$°C into this refrigerator, how long will it take for them to be cooled down to $5$°C? (Ignore any heat that leaves the plastic.)

The coefficient of performance $K=H/P$ is a dimensionless quantity. Its value is independent of the units used for $H$ and $P$, as long as the same units, such as watts, are used for both quantities. However, it is common practice to express $H$ in Btu/h and $P$ in watts. When these mixed units are used, the ratio $H/P$ is called the energy efficiency ratio ($EER$). If a room air conditioner has $K=3.0$, what is its $EER$?

In the context of refrigerators, what does the coefficient of performance ($\mathrm{COP}$) represent?