**EXPERT ANSWER**

# 2. a. Water initially at 10°C and mass flow rate 0.001 kg/s (3.6 kg/hr) enters a tube D 2 mm of high thermal conductivity and negligible wall thickness. If the tube is subjected to boiling water T-100°C on its outside surface, calculate the required length of tube if the water is to be at 90°C at the outlet of the tube assuming that the tube is long enough that the effect of the entrance length may be neglected. Estimate the entrance length. 90c boiling water at 100 C water 3.6 kg/hr 10°C b. If the flowrate were increased x10 (to 36 kg/hr) and the length of the pipe was set to be 0.5 m (not the answer to part al, what will be the outlet temperature of the water?

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