Wetting of some metallic surfaces can be inhibited bymeans

Problem 10.71

Wetting of some metallic surfaces can be inhibited by means of ion implantation of the surface prior to its use, thereby promoting dropwise condensation. The degree of wetting inhibition and, in turn, the efficacy of the implantation process vary from metal to metal. Consider a vertical metal plate that is exposed to saturated steam at atmospheric pressure. The plate is t = 1 mm thick, and its vertical and horizontal dimensions are L = 250 mm and b = 100 mm, respectively. The temperature of the plate surface that is exposed to the steam is found to be  when the opposite surface of the metal plate is held at a cold temperature, .

(a) Determine  for 2024-T6 aluminum. Assume the ion-implantation process does not promote dropwise condensation for this metal.

(b) Determine  for AISI 302 stainless steel, assuming the ion-implantation process is effective in promoting dropwise condensation.

                                                              Step by Step Solution

Step 1 of 8

Calculate the film temperature of the brass tube by the following formula:

Here,  is surface temperature of the water

 is saturated temp/

Substitute values In above equation:

From table A.6 (Thermo physical properties of saturated water). The properties of acer liquid at the film temperature 368 K are below:

Density,  

Thermal conductivity  

Dynamic viscosity,  

Specific heat of liquid,  

Kinematic viscosity,