$10\mathrm{.}48$ The Clean Air Act prohibited the production of chlorofluorocarbons $($CFCs$)$ in the United States as of $1996.$ One wid$$ly used CFC$,$ refrigerant R$-12,$ has been replaced by R$-134$a in many applications because of their similar properties, including a low boiling point at atmospheric pressure, $T_{\text{s}\text{a}\text{t}}=243K$ and $246\mathrm{.}9$ K for R$-12$ and R$-134$a$,$ respectively. Compare the performance of these two refrigerants under the following conditions. The saturated refrigerant vapor at $310$ K is condensed as it flows through a $30-mm$ diameter, $0\mathrm{.}8-$m$-$long tube whose wall temperature is maintained at $290$ K $.$ If vapor enters the tube at a flow rate of $0\mathrm{.}010k\frac{g}{s},$ what is the rate of condensation and the flow rate of vapor leaving the tube? The relevant properties of R$-12$ at $T_{\text{s}\text{a}\text{t}}=310K$ are ${}_v=50\mathrm{.}1k\frac{g}{m^3},h_{fg}=160k\frac{J}{k}g,$ and ${}_v=150{10}^{-7}N*\frac{s}{m^2}$ and those of liquid R$-12$ at $T_f=300K$ are ${}_l=1306k\frac{g}{m^3},c_{p,l}=978\frac{J}{k}g*K,{}_l=2\mathrm{.}54{10}^{-4}N*\frac{s}{m^2},k_l=0\mathrm{.}072\frac{W}{m}*K.$ The properties of the saturated R $-134$a vapor are ${}_v=46\mathrm{.}1k\frac{g}{m^3},h_{fg}=166k\frac{J}{k}g,$ and ${}_n=136{10}^{7}N*\frac{s}{m^2}$