Question

Calculate the number of tubes required for a single pass steam condenser of 2.5 m length to handle 20000 hg/hr of dry saturated steam at 60⁰C. the cooling water enters the tubes At 20⁰C and leaves at 30⁰C. the tubes are of 25 mm inside diameter. The thermal conductivity of tube material is 100 W/m-K. The water velocity is 1.5 m/s. Assume that the steam side film coefficient is 4500 W/m²-K. For water use,

Nu = 0.023 Re^0.8 Pr^0.4

      The properties of water at 25⁰C are:

      r = 996.95 kg/m³, c_p = 4178 J/kg-K,

      K = 60.78 ´ 10^–2 W/m-K, n = 0.9055 ´ 10^–6 m²/s,

            Pr = 6.22 h_fg (at 60⁰C) = 2358.5 kJ/kg.