Evaporation in a silicon film

[kcmharish]

Hai.. I have a problem with my heat transfer coefficient estimation during my evaporation measurements.

Here is the problem: Two scenarios are compared.

Case 1: I have a well defined rectangular area in a silicon wafer. Water is completely spread over it. The mass of water is known. Air is blown over the liquid to enhance the evaporation rate. At steady state, the wet bulb temperature is reached. My calculated heat transfer coefficient is very similar to the one computed using the heat and mass transfer analogy.

Case 2: Now, the area is halved.But the mass of liquid is same. AM still getting the same mass transfer coefficient, but my heat transfer coefficeint twice in this case. This is clearly against the Chilton-Colburn heat and mass transfer analogy.

Only if i take the complete area of wafer, i am able to validate the heat and mass transfer analogy.

Please help me with this.

 

[Navin A S]

The possible solutions may include:1. Adjust the velocity of air.2. Adjust the temperature of air.3. Change the geometry of the evaporation area.4. Increase the surface area of the wafer by adding additional fins or textures. 5. Use a different form of heat transfer, such as conduction or radiation.