The heat transfer enhancement techniques are widely used in many applications in the heating process to enhance the thermal performance of heat exchangers. On the other hand, nanofluids were used for the same purpose. What is the secret of focus in the use of nanofluids to enhance the thermal performance despite the risk of using them ?
Dear Dr. hayder,
As we know Nanofluids shows an effective thermophysical properties as a bulk fluids compared to host fluids which led to enhance heat exchange systems, in my point of view, that is depend on the application that you want to use nanofluid in. for example; in boiling application and as Mr. Nikolai mentioned above the nanofluid play a vital role to enhance the critical heat flux and sometimes the heat transfer coefficient because of deposition of nanoarticles on heating surface which formed a porous layer lead to wettability enhancement due to decreasing contact angle of liquid droplet on heating surface. Anyway, there is no risk to use them but there are some challenges should to overcome and make them commercially applicable. I chose this example because nanoparticles in such application have to major roles
1- Bulk effect that associated with thermophysiacl properties enhancement
2- Surface modification effect associated with of wettability, contact angle, and surface roughness etc.
My regards
I'm familiar with nanofluids used as a quenchant. Enhancement of heat transfer is due to elimination of film boiling during quenching process. Nano particles increase the first critical heat flux density and sometimes create surface nano insulating layer that decreases initial heat flux density. As for me, nanofluids, used as the quenchants, are rather expensive. It is proposed less expensive way. One can use low concentration of inverse solubility polymers in water to create nano insulating layer which eliminates film boiling. Effect is the same or better and several times cheaper.
Dear Dr. hayder,
As we know Nanofluids shows an effective thermophysical properties as a bulk fluids compared to host fluids which led to enhance heat exchange systems, in my point of view, that is depend on the application that you want to use nanofluid in. for example; in boiling application and as Mr. Nikolai mentioned above the nanofluid play a vital role to enhance the critical heat flux and sometimes the heat transfer coefficient because of deposition of nanoarticles on heating surface which formed a porous layer lead to wettability enhancement due to decreasing contact angle of liquid droplet on heating surface. Anyway, there is no risk to use them but there are some challenges should to overcome and make them commercially applicable. I chose this example because nanoparticles in such application have to major roles
1- Bulk effect that associated with thermophysiacl properties enhancement
2- Surface modification effect associated with of wettability, contact angle, and surface roughness etc.
My regards
As Mr. M. S. Kamel has been said before. The effect of using nano particles in a base fluid depends on application. I can add one different application more; using nano fluid for absorption in solar collector increases the absorption of nano fluid due to the role of solid particles in absorbing many different wavelengths, in addition to the increasing of thermal convection between fluid and solid.
As a god Galician said, "depends". we are testing nanoaditives in the cooler systems in Wind Industry and Solar Panels, and for the moment we didnt saw risk, we increased the thermal capability, wihtout changing the system itself. So it has a good bussines case. we are in the testing phase, but it is expected to reduce the failure rates, with the fans, and pumps and all the parts that entered to run when the triggered temperature is reached.
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