Dear Khaled,

In my demain, researchers used the nanofluid to increase the water productivity of a solar distiller by 50 to 60%. but there are other products, simpler and cheaper that give more intersting results.

Our journal: https://www.ijeca.info/index.php/IJECA/index

Dear Khaled,

In my demain, researchers used the nanofluid to increase the water productivity of a solar distiller by 50 to 60%. but there are other products, simpler and cheaper that give more intersting results.

Our journal: https://www.ijeca.info/index.php/IJECA/index

Dear Abderrahmane,

Many thanks for reply. and thanks for sharing your paper.

Regards

Dear Khaled,

You are welcome as authors,

You, your colleagues and your students

Drear Dr. Abderrahmane

Many thanks and wish to be in contact.

Regards

sure sir

Dear Dr. Khaled Al-Farhany,

I think you can calculate heat transfer coefficient using following models.

Viscosity of nanofluid

https://en.wikipedia.org/wiki/Viscosity#Viscosity_of_nanofluids

Thermal conductivity of nanofluid

https://en.wikipedia.org/wiki/Nanofluids_in_solar_collectors#Thermal_conductivity_of_nanofluids

Many thanks Dr Dilan S Udawattha

Dear Khaled Al-Farhany

First of all, it depends on the volume fraction of solid nanoparticles added to the base fluid. Then, there are some other parameters affecting the amount of enhancement in heat transfer rate such as material, size or shape of nanoparticles.

But in general cases, you may expect to have about 10 percent to 20 percent enhancement. Although, there are many papers reporting larger enhancements.

Dear Hamed Tahm

Thanks for your reply

Following

As noted by Yu, with volume concentrations between 0.5% and 4%, nanofluids have shown an enhancement of 15%–40% of the thermal conductivity of the base fluid.

-Yu, W., France, D. M., Routbort, J. L., and Choi, S. U. S., “Review and comparison of nanofluid thermal conductivity and heat transfer enhancements,” Heat Transfer Engineering, vol. 29, no. 5, pp. 432–460, 2008.

All numerical studies give increase in heat transfer with concentration of nanofluids. The increase ratios depend on the shape and the flow conditions.

Most of the experimental studies give highest increase in heat transfer at ratio of 1% by volume. Also, this increase ratio depends on the shape and the flow conditions.

Dear Dr Hayder Jaffal

Thanks for reply.

I am downloading the paper now

Regards

Many thanks for share these information Dr Mohamed H. Shedid

but why the experimental studies give highest increase at R=1%???

Regards

Although the thermal conductivity increases with concentrations to increase heat transfer, also the viscous sub-layer is increasing that represents a barrier for heat transfer.

This is my experimental heat transfer paper, you can have a look

Article Engine Cooling Using Al2O3/Water Nanofluids

Thanks Dr Mohamed H. Shedid

I will go through it

Regards

It depends on the nanofluid type and concentration. Not all nanofluids give better convective heat transfer coefficients. It is ascertained from recent experimental studies that lower concentrations of some specific nanofluids give better heat transfer characteristics. You can check papers of our group for more info.

I agree with you Suhaib Umer Ilyas

Dear Professor,

There are ample number of heat transfer experiments with respect to nanofluid usage. Kindly be specific to the one you have raised your clarification for, so that I could render my help and suggestion and more preferably on pipe or duct flow.

We have tried 3 nanoparticles, Alumina, TiO2 and SiO2 at different concentrations and also at different Reynolds no. The thing is in all cases you will see an improvement which for our work was from around 12 to 45 percent or so as I can remember. Theoretically the addition of any concentrations of solid nano particles or even microparticles which can stably form a suspension will improve the characteristics mainly because of the increase of conductive heat transfer coefficient (K) of the working fluid. Since most of the solids have a higher K value than liquids, the addition of solid particles will be helpful. Actually there are other phenomenons which also may be effective, like the eddies which may occur at microscopic level because of the different inertia of the particles and fluid.

Dear Masoud Derakhshandeh ,

Thermal conductivity of Alumina, TiO2, and SiO2 lower values. We can get higher thermal conductivity increment in adding diamond, graphene, CNT.

Plz refer thermal conductivity of nanofluid wiki page

https://en.wikipedia.org/wiki/Nanofluids_in_solar_collectors#Thermal_conductivity_of_nanofluids

Dear Masoud Derakhshandeh

Nanofluids heat transfer enhancement depends on various factors such as type of nanoparticles, shape, size, volume fraction, their stability, working temperature as well as type of heat tranfer fluids you used.

We cannot depict the exact rise in heat transfer. Otherwise by using nanoparticles, more than 5-10% rise was depicted with 0.1 vol% of nanoparticles. Refer this article...

Article Coding, Evaluation, Comparison, Ranking and Optimal Selectio...

Dear Masoud Derakhshandeh

Sir you cannot judge heat transfer enhancement by considering single factor but you have focussed in detail on thermophysical properties. Attached article may help you to understand the contribution of various properties on enhancement of heat transfer coefficient.

Thanks and wish you all the best.