Check Your Understanding

$2\mathrm{.}1$ Of the COP relations below, which one cannot be used to determine the COP of a Carnot heat pump?

$($a$)CO{P}_{HP,\text{r}\text{e}\text{v}}=\frac{Q_L}{Q_H-W_{in}}$

$($b$)CO{P}_{HP,\text{r}\text{e}\text{v}}=\frac{1}{1-\frac{T_l}{T_H}}$

$($c$)CO{P}_{HP,\text{r}\text{e}\text{v}}=\frac{T_H}{T_H-TL}$

$u$

$($d$)CO{P}_{HP,\text{r}\text{e}\text{v}}=\frac{Q_H}{W_{in}}$

$($e$)CO{P}_{HP,\text{r}\text{e}\text{r}}=\frac{Q_H}{Q_H-Q_L}$

$1\mathrm{.}2$ A refrigerator is claimed to absorb $5kJ$ of heat from the refrigerated space at $200K$ and rejects $10kJ$ of heat to a medium at $300K.$ This refrigerator is

$($a$)$ Reversible

$($b$)$ Irreversible

$($c$)$ Impossible

$($d$)$ Insufficient information

$1\mathrm{.}3$ A heat pump absorbs heat at a rate of $5kW$ from a cold medium at $250K$ and supplies $10kW$ of heat to a warm medium at $300K.$ The COP of this heat pump is

$($a$)1$

$($b$)2$

$($c$)3$

$($d$)4$

$($e$)5$

$\mathrm{.}4$ A refrigerator absorbs heat at a rate of $5kW$ from a cold medium at $250K$ and rejects $10kW$ of heat to a warm medium at $300K.$ The maximum possible COP a refrigerator operating between these temperature limits is

$($a$)0\mathrm{.}5$

$($b$)1$

$($c$)2$

$($d$)3$

$($e$)5$