Entropy Generation and Natural Convection Heat Transfer of (MWCNT/SWCNT) Nanoparticles around Two Spaced Spheres over Inclined Plates: Numerical Study

A numerical study is conducted to evaluate the steady natural convective heat transfer problem and entropy generation of both single wall (SWCNT) and multi wall (MWCNT) nanoparticles with water as a base liquid over two spaced spheres. The isothermally heated spheres are located between two plates of short length. The cooled plates are maintained at different inclination angles. A numerical approach based on the finite volume method and multigrid acceleration was used to solve the governing equations. The effects of nanoparticle type, volume fraction, the inclination angle of the plates and the Rayleigh numbers are well-considered. Results reveal that there is a remarkable enhancement of the average Nusselt number over the plates for MWCNT nanoparticles with 63.15% from the inclination angle 0° to 30°. Furthermore, optimal heat transfer rates over the plates for MWCNT nanoparticles equates to 1.9, which is obtained for the inclination 30° and a Rayleigh number of 10$^{6}$. However, for SWCNT nanoparticles, the same equates 0.9, which is obtained for the inclination 90° and a Rayleigh number of 10$^{6}$. The comprehensive analysis is presented under some well-defined assumptions which show the reliability of the present investigation

Synthesis, electrical properties, and kinetic thermal analysis of polyaniline/ polyvinyl alcohol - magnetite nanocomposites film

Polyaniline-poly vinyl alcohol (PANI-PVA) conducting blends containing 15 wt% aniline were synthesized by in situ polymerization of aniline. Three-phase polymer blended nanocomposites with different contents of magnetite (5, 10 and 15 wt.%) were also synthesized. We measured the current-voltage (I-V) curves for the conducting blend and its magnetite nanocomposite. We also measured their thermal stability, and performed kinetic analysis through thermogravimetric analysis. We observed that the three phase nanocomposites showed enhanced electrical conductivity compared with that of the conductive blend, and no electrical hysteresis. The PVA/PANi blend was more stable above 350∘C and the addition of Fe3O4 enhanced the thermal stability of the conductive blend. The apparent activation energy of the three phase nanocomposites was greater than those of both the pure PVA and PVA/PANi samples. These results suggest that such three phase nanocomposites could be used in a range of applications

Characterization of PVC/MWCNTs Nanocomposite: Solvent Blend

Polyvinyl Vinyl Chloride (PVC) multiwall carbon nanotubes (MWCNTs) nanocomposite flexible films were prepared using the solvent blend technique. Chloroform (CHCl3) and tetrahydrofuran ((CH2)4O) were used as solvents for MWCNTs and PVC, respectively. The effect of the solvents’ blend on electrical, optical and thermal properties of PVC/MWCNTs were investigated. The results of the Raman spectrum showed that all the characteristic bands of PVC polymer have a slight shift due to addition of MWCNTs. Electrical results showed that the nanocomposite samples with chloroform volume ratios of 10% and 25% had nearly the same conductivity. This is attributed to the formation of the MWCNTs network, which assisted in electrical conductivity. The I-V hysteresis curve decreases as the temperature increases and as it approaches the glass transition temperature. The non-isothermal kinetics analysis for PVC and PVC/MWCNTs were investigated by Thermogravimetry Analysis (TGA) using the model-free kinetic method. The non-isothermal measurements were carried out at five heating rates of 5 to 40∘C/min. The results show that the main decomposition process has constant apparent activation energies for all samples. The use of the bi-solvent method has improved the dispersion of untreated MWCNTs, and this has been reflected on the stability of both electrical and thermal properties

Application of Fourier Sine Transform to Carbon Nanotubes Suspended in Ethylene Glycol for the Enhancement of Heat Transfer

There is no denying fact that nanoparticles of carbon nanotubes are employed to improve the performance of thermal stability in comparison with traditional nanoparticles, this is because nanoparticles of carbon nanotubes possess outstanding material properties. In this manuscript, a mathematical model of mixed convective flow based on carbon nanotubes suspended in ethylene glycol has been developed and derived by means of Fourier Sine transform. In order to analyze the thermophysical properties of nanofluid, the temperature and velocity profiles have been investigated through fractional derivative and integral transforms. The comparative analysis of single and multi-walled carbon nanotubes has been presented for the sake of enhancement of heat transfer. It is worth mentioning that embedded rheological parameters have shown the sensitivity for the enhancement of heat transfer with and without fractional techniques through graphical illustration

Application of Fourier Sine Transform to Carbon Nanotubes Suspended in Ethylene Glycol for the Enhancement of Heat Transfer

There is no denying fact that nanoparticles of carbon nanotubes are employed to improve the performance of thermal stability in comparison with traditional nanoparticles, this is because nanoparticles of carbon nanotubes possess outstanding material properties. In this manuscript, a mathematical model of mixed convective flow based on carbon nanotubes suspended in ethylene glycol has been developed and derived by means of Fourier Sine transform. In order to analyze the thermophysical properties of nanofluid, the temperature and velocity profiles have been investigated through fractional derivative and integral transforms. The comparative analysis of single and multi-walled carbon nanotubes has been presented for the sake of enhancement of heat transfer. It is worth mentioning that embedded rheological parameters have shown the sensitivity for the enhancement of heat transfer with and without fractional techniques through graphical illustration

Heat Transfer and Fluid Circulation of Thermoelectric Fluid through the Fractional Approach Based on Local Kernel

A thermoelectric effect occurs when a material’s intrinsic property directly converts temperature differences applied across its body into electric voltage. This manuscript presents the prediction for maximum and optimal heat transfer efficiency of a thermoelectric fluid via the non-classical approach of the differential operator. The fractionalized mathematical model is also established to analyze the efficiency and characteristics of thermoelectric fluid through a temperature distribution and velocity field. The comprehensive analytical approach of integral transforms and Cardano’s method are applied to provide analytical solutions that include the dynamic investigation of the temperature distribution and velocity field. A dynamic investigation of the temperature distribution and velocity field of the thermoelectric fluid is explored on the basis of magnetization and anti-magnetization, which describe the behavior for sine and cosine sinusoidal waves. The rheological parameter, i.e., magnetization, suggests that by employing varying magnetic fields, the magnetized intensity generates 34.66% of the magnetic hysteresis during the thermoelectric effect

Heat Transfer and Fluid Circulation of Thermoelectric Fluid through the Fractional Approach Based on Local Kernel

A thermoelectric effect occurs when a material’s intrinsic property directly converts temperature differences applied across its body into electric voltage. This manuscript presents the prediction for maximum and optimal heat transfer efficiency of a thermoelectric fluid via the non-classical approach of the differential operator. The fractionalized mathematical model is also established to analyze the efficiency and characteristics of thermoelectric fluid through a temperature distribution and velocity field. The comprehensive analytical approach of integral transforms and Cardano’s method are applied to provide analytical solutions that include the dynamic investigation of the temperature distribution and velocity field. A dynamic investigation of the temperature distribution and velocity field of the thermoelectric fluid is explored on the basis of magnetization and anti-magnetization, which describe the behavior for sine and cosine sinusoidal waves. The rheological parameter, i.e., magnetization, suggests that by employing varying magnetic fields, the magnetized intensity generates 34.66% of the magnetic hysteresis during the thermoelectric effect

Effects of a novel hybrid turbulator tape on the thermohydraulic performance and irreversibility of a solar air heater

Renewable energy from the sun has been a rapidly expanding field in recent years, because to its many advantages as a sustainable, cost-effective, and environmentally friendly power source. Energy drives economic growth and industrialization today. Air heating is a prominent solar energy utilization for space and process heating including washing, desalination, crop drying, and others. To improve energy efficiency, this study examined several designs of novel hybrid tape within an affordable solar-powered air heater. Solar air heaters can improve their heating efficiency by adding additional novel swirl generator. Many research have been done in this subject, however novel geometries are being proposed to better the heat transfer enhancement (HTE)-blowing power penalty tradeoff. Hybrid turbulator tapes are new, and there is no parametric investigation on their advantages. To cover this gap in this research, utilized air as the working fluid to investigate the pressure drop and heat transfer characteristics inside a uniformly heated circular tube with hybrid turbulator tape inserts. The aim was to cover the turbulent flow regime by varying the Reynolds number from 10,104 to 73,788. The thermohydraulic performance with pitch, length, and width ratios is investigated in this work. In comparison to a plain tube, it is observed an average increase of 91% and 39% in the Nusselt number and friction factor, respectively. This indicates a significant improvement in the tube's performance. It is also found that the important thermal performance factor exceeded one for all tape combinations. Novel correlations have also developed. With such encouraging results, using the tested turbulator in a solar air heater for improved performance is feasible