EXERCISE

$6\mathrm{.}17\mathrm{.}47$: $($Problem $5\mathrm{.}47$ in the $9$ th edition$).$

$($a$)$ To maintain a dwelling steadily at $68F$ on a day when the outside temperature is $32F.$ heating must be provided at an average rate of $740Bt\frac{u}{m}in.$ Compare the electrical power required, in kW $,$ to deliver the heating using $($a$)$ electrical$-$resistance heating, $($b$)$ a heat pump whose coefficient of performance is $3\mathrm{.}0.($c$)$ a reversible heat pump operating between hot and cold reservoirs at $68F$ and $32F,$ respectively.