A heat exchanger is to be designed to heat a flow of molten bismuth from 377?C to 477?C. The heat exchanger consists of a 50 mm ID tube with surface temperature maintained uniformly at 500?C by an electrical heater. Find the length of the tube and the power required to heat 4 kg/s and 8 kg/s of bismuth.GIVENSMolten Bismuth flows through a tubeBismuth temperature: Inlet (Tb,in) = 377?C Outlet (Tb,out) = 477?CTube inside diameter (D) = 50 mm = 0.05 mSurface temperature (Ts) = 500?CASSUMPTIONSSteady stateUniform and constant surface temperatureLosses from the heater arenegligible

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T.- 500°C Blemuth Tain = 377°C m =4 kg/s D-0.05 m Toout =477°C 8 kg/s or L-?