scholarly journals Flow and heat transfer of hybrid nanofluid over a permeable shrinking cylinder with Joule heating: A comparative analysis

2020 ◽  
Vol 59 (3) ◽  
pp. 1787-1798 ◽  
Author(s):  
Najiyah Safwa Khashi'ie ◽  
Norihan Md Arifin ◽  
Ioan Pop ◽  
Nur Syahirah Wahid
2020 ◽  
Vol 64 ◽  
pp. 251-263 ◽  
Author(s):  
Najiyah Safwa Khashi'ie ◽  
Norihan Md Arifin ◽  
Roslinda Nazar ◽  
Ezad Hafidz Hafidzuddin ◽  
Nadihah Wahi ◽  
...  

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tawfeeq Abdullah Alkanhal

Purpose This paper aims to disperse the silicon dioxide in water (as the mono nanofluid [MN]) and then, carbon nanotube (CNT)-silica composite in water (as the hybrid nanofluid [HN]). Design/methodology/approach Nanofluids have gained lots of attention through the recent years. Due to their usage in the industries and also medical applications, they have high protentional to be studied in different aspects. The most common study for the nanofluids is to understand the heat transfer capacity for each material in each fluid. These material(s) or fluid(s) can be one (mono nanofluid) or more than one (hybrid nanofluid). Findings The mixture of two solids is to assess the unique properties of each material and also to decrease the cost of experiments. The heat transfers for both MN and HN were measured at volume fractions up to 1.0%, and temperatures up to 50°C. Also, the heat transfers were compared. By more CNT, thermal conductivity was enhanced about 17.39% (from 12.42% of MN to 29.81% of HN). Originality/value X-Ray diffraction and field emission scanning electron microscope (FESEM) were examined for mono solids and the composite. After the experimental study, for MN and HN, four novel correlations calculated.


Author(s):  
Ainul Haque ◽  
Ameeya Kumar Nayak

In this paper, a mathematical model has been developed to analyze the combined electroosmotic and pressure driven flow of power law fluids in a micro channel in the presence of Joule heating effects. The effects of Navier slip boundary condition and thermal radiation is examined for effective heat transfer in a hydrophobic microchannel. The analytical treatment has been performed for fluid flow and heat transfer effects in terms of flow governing parameters. This study highlights the effect of channel height to the electric double layer thickness and observed the flow variation due to heat transfer effect with the available scientific data. For a pure EOF, velocity slip have more significant role to get a maximum flow rate as expected. For both pseudo-plastic and dilatent fluids Nusselt number is decreased with the increment of the hydrophobic parameter and dimensionless pressure gradient where as increment in Joule heating effect enhance the heat transfer rate.


Author(s):  
Nataliia Fialko ◽  
◽  
Julii Sherenkovskiy ◽  
Nataliia Meranova ◽  
Serhii Aloshko ◽  
...  

For microjet burners of the stabilizer type, a study of the regularities of the natural gas flow in the inner cavity of the flame stabilizer has been carried out. A comparative analysis of the features of heat transfer from the inner surfaces of the stabilizer walls is carried out for two variants of its configuration: flat and in the presence of trapezoidal niches on its lateral surfaces.


2020 ◽  
Vol 30 (10) ◽  
pp. 4583-4606 ◽  
Author(s):  
Najiyah Safwa Khashi’ie ◽  
Norihan Md Arifin ◽  
Ioan Pop ◽  
Roslinda Nazar ◽  
Ezad Hafidz Hafidzuddin ◽  
...  

Purpose This paper aims to scrutinize the analysis of non-axisymmetric Homann stagnation point flow and heat transfer of hybrid Cu-Al2O3/water nanofluid over a stretching/shrinking flat plate. Design/methodology/approach The similarity transformation which fulfils the continuity equation is opted to transform the coupled momentum and energy equations into the nonlinear ordinary differential equations. Numerical solutions which are elucidated in the tables and graphs are obtained using the bvp4c solver. Findings Non-unique solutions (first and second) are feasible for both stretching and shrinking cases within the specific values of the parameters. First solution is the physical/real solution based on the execution of stability analysis. An upsurge of the ratio of the ambient fluid strain rate to the plate strain rate can delay the boundary layer separation, whereas a boost of the ratio of the ambient fluid shear rate to the plate strain rate only accelerates the separation of boundary layer. The heat transfer rate of hybrid nanofluid is greater for the stretching case than the shrinking case. However, for the shrinking case, the heat transfer rate intensifies with the increment of the copper (Cu) nanoparticles volume fraction, whereas a contrary result is found for the stretching case. Originality/value The present numerical results are original and new. It can contribute to other researchers on electing the relevant parameters to optimize the heat transfer process in the modern industry, and the right parameters to generate non-unique solution so that no misjudgment on flow and heat transfer features.


2020 ◽  
Vol 66 ◽  
pp. 157-171 ◽  
Author(s):  
Najiyah Safwa Khashi'ie ◽  
Norihan Md Arifin ◽  
Ioan Pop ◽  
Roslinda Nazar ◽  
Ezad Hafidz Hafidzuddin ◽  
...  

2019 ◽  
Vol 29 (12) ◽  
pp. 4875-4894 ◽  
Author(s):  
Iskandar Waini ◽  
Anuar Ishak ◽  
Ioan Pop

Purpose The purpose of this paper is to study the steady mixed convection hybrid nanofluid flow and heat transfer past a vertical thin needle with prescribed surface heat flux. Design/methodology/approach The governing partial differential equations are transformed into a set of ordinary differential equations by using a similarity transformation. The transformed equations are then solved numerically using the boundary value problem solver (bvp4c) in Matlab software. The features of the skin friction coefficient and the local Nusselt number as well as the velocity and temperature profiles for different values of the governing parameters are analyzed and discussed. Findings It is found that dual solutions exist for a certain range of the mixed convection parameter where its critical values decrease with the increasing of the copper (Cu) nanoparticle volume fractions and for the smaller needle size. It is also observed that the increasing of the copper (Cu) nanoparticle volume fractions and the decreasing of the needle size tend to enhance the skin friction coefficient and the local Nusselt number on the needle surface. A temporal stability analysis is performed to determine the stability of the dual solutions in the long run, and it is revealed that only one of them is stable, while the other is unstable. Originality/value The problem of hybrid nanofluid flow and heat transfer past a vertical thin needle with prescribed surface heat flux is the important originality of the present study where the dual solutions for the opposing flow are obtained.


Author(s):  
Iskandar Waini ◽  
Anuar Ishak ◽  
Ioan Pop

PurposeThis paper aims to investigate the steady flow and heat transfer of a Cu-Al2O3/water hybrid nanofluid over a nonlinear permeable stretching/shrinking surface with radiation effects. The surface velocity condition is assumed to be of the power-law form with an exponent of 1/3. The governing equations of the problem are converted into a system of similarity equations by using a similarity transformation.Design/methodology/approachThe problem is solved numerically using the boundary value problem solver (bvp4c) in Matlab software. The results of the skin friction coefficient and the local Nusselt number as well as the velocity and temperature profiles are presented through graphs and tables for several values of the parameters. The effects of these parameters on the flow and heat transfer characteristics are examined and discussed.FindingsResults found that dual solutions exist for a certain range of the stretching/shrinking and suction parameters. The increment of the skin friction coefficient and reduction of the local Nusselt number on the shrinking sheet is observed with the increasing of copper (Cu) nanoparticle volume fractions for the upper branch. The skin friction coefficient and the local Nusselt number increase when suction parameter is increased for the upper branch. Meanwhile, the temperature increases in the presence of the radiation parameter for both branches.Originality/valueThe problem of Cu-Al2O3/water hybrid nanofluid flow and heat transfer over a nonlinear permeable stretching/shrinking surface with radiation effects is the important originality of the present study where the dual solutions for the flow reversals are obtained.


Author(s):  
Huei Chu Weng

The presence of current flow in an electric and magnetic field results in electromagnetic force and joule heating. It is desirable to understand the roles of electromagnetic force and joule heating on gas microflow and heat transfer. In this study, a mathematical model is developed of the pressure-driven gas flow through a long isothermally heated horizontal planar microchannel in the presence of an external electric and magnetic field. The solutions for flow and thermal field and characteristics are derived analytically and presented in terms of dimensionless parameters. It is found that an electromagnetic driving force can be produced by a combined non-zero electric field and a negative magnetic field and results in an additional velocity slip and an additional flow drag. Also, a joule heating can be enhanced by an applied positive magnetic field and therefore results in an additional temperature jump and an additional heat transfer.


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