Plot the coefficient of performance versus the temperature of a high$-$temperature reservoir for a

Carnot refrigerator whose low$-$temperature reservoir is at $5C$ and whose high$-$temperature

reservoir varies between $7C$ and $50C.$

$C{O}_2$ in a piston$-$cylinder assembly goes from $P_1=150$kPa,$T_1=300K$ to $P_2=500$kPa,$T_2=370K.$ The

compression requires $300$ kJ of work $($into the system$).$ Assuming it is an ideal gas with constant

specific heats, find the heat transfer in $k\frac{J}{k}g$ and the change in specific entropy.

$2$ kg of saturated water at $100C$ initially has a quality of $0\mathrm{.}75.$ Heat is removed from the water at

constant pressure until the quality is at a lower value, $x_2.$ Plot the amount of heat transfer that

occurs and the change in entropy of the water versus the quality, $x_2.$ Vary $x_2$ from $0$ to $0\mathrm{.}5.$