A two$-$pass surface condenser is to be designed using overall heat transfer coefficient of $480$Btu$/$F$-$ft$^2$ of outside tube surface. The tubes are to be $1$ inch diameter with $1/16$ in walls $($or $7/8$in$.$ inside diameter$).$ Entering circulating water velocity is to be $6$ft$/$s$.$ Steam enters the condenser at a rate of $100,000$lb$/$hr at a pressure of one psia and an enthalpy of $1090$ Btu$/$lb$.$ Condensate leaves at saturated liquid at one psia. Circulating water enters the condenser at $85$ deg. F and leaves at $95$ deg F$.$ Note: $1$ psia condensate has temperature of $101\mathrm{.}7$ deg. F$.$ Wet steam entering becomes condensate at $101\mathrm{.}7$ deg. F with hf$=69\mathrm{.}72$ Btu$/$lb$.$ Calculate the total number of tubes to be used in each pass.

answer $1513$ tubes