Nano layers have proved different radiation characteristics. So, what would be the effects of nano - layers as coating in inner or outter side of pipe flows on genral heat transfer characteristics? Does the conduction, convection, and radiation will all change favorably? How to model these?
Dear Ahmad,
I have some experience with the surface finish of copper surfaces. We looked at getting super-hydrophilic surfaces in order to drastically improve the wettability. Using oxide coating processes we could control the type of copper-oxide and texturing that was deposited on the surface. Especially the copper(II)-oxide or cupric oxide is very beneficial for reducing the contact angle and increasing the surface potential energy.
In the linked publication you can see some images of the copper surfaces we treated. This was mainly for heat pipe applications.
Article Integrated Design and Manufacturing of Flat Miniature Heat P...
I understand that the question is related to single phase fluid flow associated with heat transfer.
With single phase fluid flow, pressure drop is expected to decrease due to lower frictional resistance of the surface. It is expected to have a marginal influence on heat transfer and can depend on the particle size of the nanomaterial. The heat transfer may enhance/decrease depending on various parameters, contact angle being one such as Dr. Wessel has stated. It is worth exploring this area. It has a wide range of applications.
For low heat flux boiling, a superhydrophobic surface like that suggested by Wits sounds good. For single phase flow, carefully designed surface geoemtry and high heat flux CJ Kim's bi-philic surface would be best.
Dear Scientists and scholars,
Many thanks for all very useful responses. Some studies on radiative properties of nano-layers were conducted by Dr S.A.A. Oloomi a former PhD student of us suggesting various characteristics using different nano-layers. For inner fluid side, the information for single phase and boiling condition is nicely described by you. However, for such coating outer side of the pipes with possible radiation and also free or forced convection with air may also useful for investigation.
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