Reconsider Prob. 11–24. Using EES (or other) software, plot the overall heat transfer coefficient based on the inner surface as a function of fouling factor as it varies from 0.0001 m² · K/W to 0.0008 m² · K/W, and discuss the results.

Data from problem 24

Repeat Prob. 11–23, assuming a fouling factor R_{f, i} = 0.0005 m² · K/W on the inner surface of the tube.

Data from problem 23

Water at an average temperature of 110°C and an average velocity of 3.5 m/s flows through a 5-m-long stainless steel tube (k = 14.2 W/m · K) in a boiler. The inner and outer diameters of the tube are D_i = 1.0 cm and D_o = 1.4 cm, respectively. If the convection heat transfer coefficient at the outer surface of the tube where boiling is taking place is h_o = 8400 W/m² · K, determine the overall heat transfer coefficient U_i of this boiler based on the inner surface area of the tube.