$8-16.$ Brine is to be evaporated in a multistage falling$-$film evaporator, and is fed to

the top of a bundle of horizontal $5cm-$O$.$D$.,2mm-$wall$-$thickness stainless steel

tubes $3$mhigh, at $0\mathrm{.}010k\frac{g}{s}$ per tube. Hot water at $340K$ is fed to the bottom

of the bundle and flows inside the tubes at $0\mathrm{.}050k\frac{g}{s}$ tube. If the saturation

temperature in the stage is $330K,$ what is the vapor production per tube?