In a single$-$effect, forced circulation type evaporator with a heat transfer area of $40$ m$2,$ an aqueous solution containing $20\%$ NaOH is concentrated to $50\%$ NaOH concentration. The feed flow is $9000$ kg$/$h at $66$ C$.$ Evaporation is performed in an environment where the separator pressure is $150$ mmHg$.$ The heat capacity of the steam formed under these conditions is $0\mathrm{.}45$ kcal$/$kgC$.$ The total pressure of the heating steam is $4\mathrm{.}283$ kg$/$cm$2.$ Calculate the entire heat conduction coefficient of the evaporator, assuming that water vapor leaves the heater at the condensation temperature, solvent vapor does not carry solution droplets, and heat loss by radiation is neglected. Data: $1$ atm: $1\mathrm{.}033$ kg$/$cm$2,$ Saturated water vapor table, Duhring diagram, Enthalpy$-$concentration Graph