Chapter 8, Problem 8.41P

Water flows through a thick-wailed tube with an innerdiameter of 12 mm and a length of 8 in. The tube isimmersed in a wel1-stirred, hot reaction tank maintainedat 85°C, and the conduction resistance of the tube wall(based on the inner surface area) is $R_{cd}^n=0.002{\text{m}}^2\cdot \text{K/W}$ .The inlet temperature of the process fluid is $T_{m,i}=20$ °C, and the flow rule is 33 kg/h.

(a) Estimate the outlet temperature of the process fluid. $T_{m,o}=20$ . Assume, and then justify, fully developed flowand thermal conditions within the tube.

(b) Do you expect $T_{m,o}$ to increase or decrease if combined thermal and hydrodynamic entry conditionsexist within the tube? Estimate the outlet temperature of the water for this condition.