Note: Please prepare a brief typed report where solution methodology, including all applied equations

and correlations, are provided. Students can prepare solutions in teams of two, if they prefer.

Please submit your report electronically via "End of Term Assignment" assignment.

Problem 1.

a) Consider fully developed flow of atmospheric pressure pure water, at a mean temperature of 300

K, in a 2 cm-diameter hydraulically smooth tube, with a Reynolds number of 106.

For the onset of nucleate boiling (ONB) to occur, a superheated layer of liquid must form

adjacent to the tube wall. For wall surface temperatures in the 375 to 385 K, calculate and plot

the thickness of the superheated liquid layer as well as the heat flux that needs to be imposed in

order to cause the needed heat flux.

Also, suppose micro bubbles with diameters approximately equal to the thickness of the

superheated liquid layer are generated and released into the flow. According to Kolmogorov's

theory of small turbulence scale, which eddy size range do the bubbles compare with?

b) Now consider fully developed flow of atmospheric pressure pure water vapor, at a mean

temperature of 376 K, flowing in a 2 cm-diameter hydraulically smooth tube, with a Reynolds

number of 10%. For wall surface temperatures in the 300 to 350 K, calculate and plot the thickness

of the supercooled vapor (i.e., vapor at a temperature below saturation temperature) layer as well

the heat flux that needs to be imposed in order to cause the needed heat flux. Discuss whether, in

your opinion, such flow can be stable.