Question

water flowing through a smooth pipe of inner diameter di = 25 mm is heated at the rate from 30 c to 50 c. the mass flow rate is of 1 kg/s. the wall temperature of the pipe is measured to be 9.1 c above the average fluid temperature all along its length.

a. what is the length of the tube required for heating?

b. what are the values of the heat flux and the temperature of the wall at the exit?

Answer 1

Given that inner diameter of the pipe di= 25mm. - initial temperature of water To = 300 - exit temperabore of coater To = Joc mass flow enake of water inau kals wall temperature of pipe To = Treean ta.ic Properties of water at Tang= Titto = 30450 2 = uo'c P= 992. 2 kg/m3 k=0.6178 wink all z o.ooo6533 NS Por=40422 cp = 4182 Jingk - gate of heat transfer Q=ric (To-T;) Q =(1) Cui82) (50-30) 83.6uo w Reynold's number evo Rea um ITD. De= (u) a) to.0006533) (I) (0.025). le= 77957.ul -- Re 2300 > The how is tusibulect frow.

for a tushulen -> a average Nussell Number how through a NO = 0.023 Pipe is 0.023 (Rejo. Psija fog healing process NO = (0.023)( 999 97.41) (4.422) 0.4 No= 341.55 = ño af - (34155) C06178) 0.025 ñ = suno. 51 W/m²K. 2) Convection heat transfer "'Ts-Tw=q.ic Qcony has CTS-TW). =) 830 640 = (su40.51) (F) (0825) (L) (a. 0.0138 m. -> heat fox heat for = q = q- QJ BLS 83.640 (I) (0.025 Cools q= 77.169 kW/m²

- Temperature of the wall at the enit Tg = Tow tal "I at enit Tw= To 3500 2) Is= sota. To=59.100