Prediction of thermal and energy transport of MHD Sutterby hybrid nanofluid flow with activation energy using Group Method of Data Handling (GMDH)

The present research work pursues GMDH for predicting thermal and energy transport of 2-D radiative magnetohydrodynamic (MHD) flow of hybrid Sutterby nanofluid across a moving wedge with activation energy. An exclusive class of nanoparticles SWCNT-Fe(3)O(4 )and MWCNT-Fe3O4 are dispersed into the ethylene glycol as regular fluid. The hybrid nanofluid mathematical model has been written as a system of partial differential equations (PDEs), which are then converted into ordinary differential equations (ODEs) through similarity replacements. Numerical solutions are attained Runge-Kutta-Fehlberg's fourth fifth-order (RKF-45) scheme by adopting the shooting technique. The ranges of diverse sundry parameters used in our study are Hartree parameter 0.1 <= m <= 0.5, magnetic parameter 0.3 <= M <= 1, Deborah number 0.1 <= De <= 1, moving wedge parameter 0.3 <= gamma <= 0.9, Reynolds number 0 <= Re <= 2.5, solid volume fraction of Fe3O4 and CNTs0.005 <= phi(1) <= 0.1,0.005 <= phi(2) <= 0.06, Browanian motion 0.1 <= Nb <= 0.4, thermophoresis parameter 0.1 <= Nt <= 0.25, Eckeret number 0.05 <= Ec <= 1, radiation parameter 1 <= R-d <= 2.5, Lewis number 0.5 <= Le <= 1.5, chemical reaction rate 0.1 <= sigma <= 0.7, heat source parameter, 0 <= delta <= 1.5 and activation energy 1 <= E <= 4 which shows up during the speed, thermal, and focus for Fe3O4/C2H6O2 nanofluid and CNTs-Fe3O4/C2H6O2 hybrid nanofluid. Additionally, the friction coefficient (C-fx), rate of heat transport (H-tx), and rate of nanoparticle transport (Nt(x) are calculated using GMDH. The numerical results for the current analysis are illustrated via tables, graphs, and contour plots. The efficiency of the proposed GMDH models is assessed using statistical measures such as MSE, MAE, RMSE, R, Error mean and Error StD. The predicted values are very close to the numerical results, and the coefficient of determination R-2 of C-fx,N-tx, and H-tx are 1, 0.97836 and 0.9960, respectively, which shows the best settlement

Thermal conductivity of nanofluids: a review on prediction models, controversies and challenges

In recent years, the nanofluids (NFs) have become the main candidates for improving or even replacing traditional heat transfer fluids. The possibility of NFs to be used in various technological applications, from renewable energies to nanomedicine, has made NFs and their thermal conductivity one of the most studied topics nowadays. Hence, this review presents an overview of the most important advances and controversial results related to the NFs thermal conductivity. The different techniques used to measure the thermal conductivity of NFs are discussed. Moreover, the fundamental parameters that affect the NFs thermal conductivity are analyzed, and possible improvements are addressed, such as the increase of long-term stability of the nanoparticles (NPs).The most representative prediction classical models based on fluid mechanics, thermodynamics, and experimental fittings are presented. Also, the recent statistical machine learning-based prediction models are comprehensively addressed, and the comparison with the classical empirical ones is made, whenever possible.This work has been funded by Portuguese national funds of FCT/MCTES (PIDDAC) through the base funding from the following research units: UIDB/00532/2020 (Transport Phenomena Research Center–CEFT), UIDB/04077/2020 (MEtRICs) and UIDP/04436/2020.The authors are also grateful for the funding of FCT through the projects POCI-01-0145-FEDER-016861, POCI-01- 0145-FEDER-028159, NORTE-01-0145-FEDER-029394, NORTE-01-0145-FEDER-030171, funded by COMPETE2020, NORTE2020, PORTUGAL2020, and FEDER

Investigation into stability and thermal-fluid behaviour of hybrid nanofluids as heat transfer fluids

Thesis (PhD (Mechanics))--University of Pretoria, 2021.The need to improve the poor thermal conductivity of conventional fluids to produce adequate heat transfer fluid cannot be over-emphasized, knowing fully well that heat transfer is key in any engineering process line. Hence, the birth of nanofluids, which is the formulation of a composite of suspended nanoparticles in a basefluid. Nanofluids have found wide applications ranging from heat exchangers, electronic cooling, automotive industry, medical, military, solar energy, manufacturing industry, to mention but a few. But the limitations of nanofluids led to the entrance of a new working fluid named binary nanofluid and ternary nanofluid. This study experimented with the trio influence of temperature (T), percent weight ratios (PWRs), nanoparticles size (NS) on the thermophysical behaviour of MgO–ZnO/Deionised water binary nanofluids (BNFs). 20 nm nano-size of ZnO nanoparticles were hybridised with MgO nanoparticles of nano-sizes 20 nm and 100 nm, and dispersed in deionised water to prepare 0.1 vol% binary nanofluids for percent weight ratios of MgO:ZnO (20:80, 40:60, 60:40 and 80:20). The viscosity (μ), electrical conductivity (σ), pH, and thermal conductivity (κ) of the binary nanofluids were experimentally evaluated for temperature 20 to 50 °C. Morphology was checked, and stability was monitored. The impact of temperature, PWRs, and nano-size on the pH, μ, σ, and κ of the binary nanofluid were ordered as PWR >NS >T, NS> PWR>T, T>NS >PWR, and T >NS >PWR, respectively. Using the obtained experimental dataset, correlations were proposed for the thermal property of each binary nanofluid as a function of temperature. Also, investigating the trio impact of PWR, temperature and � on the thermophysical characteristics of MgO-ZnO/DIW BNFs, to help close up the scarce literature gap. 20 nm nanoparticle sizes of MgO and ZnO were hybridized together and dissolved in deionized water to formulate 0.1 vol% and 0.05 vol.% binary nanofluids (NFs) for PWR of 20:80, 40:60, 60:40, 80:20 (MgO:ZnO). The κ for all BNFs was enhanced under the impact of rising temperature, with maximum κ enhancement of 5.60% and 22.07% relative to the deionised water (DIW) achieved for 0.05 vol% and 0.10 vol%, separately. The σ was enhanced slightly under the influence of increasing temperature, with maximum enhancement of 21.82% and 30.91% achieved for 0.050 vol% and 0.10 vol%, respectively. In addition, viscosity under temperature increase exhibited a decreasing pattern for all nanohybrids and basefluid. Furthermore, to better harness the benefit of the BNFs for thermal application, thermoelectrical conductivity (TEC) was evaluated with BNFs of 0.05 vol% observed to have higher TEC values than 0.10 vol% BNFs. The BNFs were found suitable as thermal fluids. A novel manner of furthering thermo-convection behaviour of thermal applications is the use of BNFs as heat transfer fluids. This study experimented the natural convection behaviour of MgO-ZnO NPs suspended in basefluid for � = 0.050 vol.% and 0.10 vol% at percent weight ratios of 20:80, 40:60, 60:40, 80:20 (MgO:ZnO) inside a square enclosure. Factors like Rayleigh number, Nusselt number (Nuav), coefficient of convective heat transfer (hav), and heat transfer rate (Qav) for various temperatures (20°C to 50°C) were examined. PWRs and temperature gradient of BNPs inside the binary nanofluids was observed to augment Nuav, hav, and Qav. Also, highest improvement of 72.60% (Nuav), 76.01% (hav), and 72.20% (Qav) was achieved. Employing BNFs in square enclosure yielded fine improvement for natural convection behaviour. Artificial intelligence (AI) methods, like artificial neural network (ANN) and surface fitting method were deployed to model the thermal conductivity of BNFs. For the ANN model, a learning algorithm was developed to determine the optimum neuron number. The ANN having 19 neurons in the inner layer got the optimized performance. A surface fitting method was also used on the experimental data, and the generated surface shows the behaviour of the BNFs. The outcome affirmed that the designed ANN model is best for predicting the thermal conductivity of MgO-ZnO/DIW binary nanofluids for different temperatures, nanoparticle sizes, PWRs and volume concentration over the surface fitting method.University of Pretoria Postgraduate Bursary for Doctoral Students.Olabisi Onabanjo University, Ago-Iwoye, Nigeria.Tertiary Education Trust Fund (TETFund), Abuja, Nigeria.Mechanical and Aeronautical EngineeringPhD (Mechanics)Unrestricte

The viscosity of nanofluids : a review of the theoretical, empirical, and numerical models

The enhanced thermal characteristics of nanofluids have made it one of the most raplidly growing research areas in the last decade. Numerous researches have shown the merits of nanofluids in heat transfer equipment. However, one of the problems is the increase in viscosity due to the suspension of nanoparticles. This viscosity increase is not desirable in the industry, especially when it involves flow, such as in heat exchanger or microchannel applications where lowering pressure drop and pumping power are of significance. In this regard, a critical review of the theoretical, empirical, and numerical models for effective viscosity of nanofluids is presented. Furthermore, different parameters affecting the viscosity of nanofluids such as nanoparticle volume fraction, size, shape, temperature, pH, and shearing rate are reviewed. Other properties such as nanofluid stability and magnetorheological characteristics of some nanofluids are also reviewed. The important parameters influencing viscosity of nanofluids are temperature, nanoparticle volume fraction, size, shape, pH, and shearing rate. Regarding the composite of nanofluids, which can consist of different fluid bases and different nanoparticles, different accurate correlations for different nanofluids need to be developed. Finally, there is a lack of investigation into the stability of different nanofluids when the viscosity is the target point.National Research Foundation of South Africa (NRF), Stellenbosch University / University of Pretoria Solar Hub, CSIR, EEDSM Hub, NAC, and IRT SEED.http://www.tandfonline.com/loi/uhte202016-09-30hb201

The promise of nanofluids: A bibliometric journey through advanced heat transfer fluids in heat exchanger tubes

© 2024 The Author(s). Published by Elsevier B.V. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Thermal management is a critical challenge in advanced systems such as electric vehicles (EVs), electronic components, and photoelectric modules. Thermal alleviation is carried out through the cooling systems in which the coolant and the heat exchangers are the key components. The study examines recent literature on nanofluids and heat exchanger tubes along with state-of-the-art concepts being tested for heat transfer intensification. The performance of nanofluids in several common heat transfer tubes’ geometries/configurations and the effectiveness of novel heat transfer augmentation mechanisms are presented. Promising results have been reported, showing improved heat transfer parameters with the use of nanofluids and intensification mechanisms like turbulators, fins, grooves, and variations in temperature and flow velocity. These mechanisms enhance dispersion stability, achieve a more uniform temperature distribution, and reduce the boundary layer thickness, resulting in lower tube wall temperatures. Moreover, introducing flow pulsations and magnetic effects further enhances particle mobility and heat exchange. However, there are limitations, such as increased frictional losses and pressure drop due to magnetic effects. The combination of nanofluids, novel heat exchanger tube geometries, and turbulators holds great promise for highly efficient cooling systems in the future. The study also presents a bibliometric analysis that offers valuable insights into the impact and visibility of research in the integration of nanofluids into heat transfer systems. These insights aid in identifying emerging trends and advancing the field towards more efficient and compact systems, paving the way for future advancements.Peer reviewe

Onset of the Mutual Thermal Effects of Solid Body and Nanofluid Flow over a Flat Plate Theoretical Study

The falling and settling of solid particles in gases and liquids is a natural phenomenon happens in many industrial processes. This phenomenon has altered pure forced convection to a combination of heat conduction and heat convection in a flow over a plate. In this paper, the coupling of conduction (inside the plate) and forced convection of a non-homogeneous nanofluid flow (over a flat plate) is investigated, which is classified in conjugate heat transfer problems. Two-component four-equation non-homogeneous equilibrium model for convective transport in nanofluids (mixture of water with particles<100nm) has been applied that incorporates the effects of the nanoparticles migration due to the thermophoresis and Brownian motion forces. Employing similarity variables, we have transformed the basic non-dimensional partial differential equations to ordinary differential ones and then solved numerically. Moreover, variation of the heat transfer and concentration rates with thermal resistance of the plate is studied in detail. Setting the lowest dependency of heat transfer rate to the thermal resistance of the plate as a goal, we have shown that for two nanofluids with similar heat transfer characteristics, the one with higher Brownian motion (lower nanoparticle diameter) is desired

Applied Mathematics and Computational Physics

As faster and more efficient numerical algorithms become available, the understanding of the physics and the mathematical foundation behind these new methods will play an increasingly important role. This Special Issue provides a platform for researchers from both academia and industry to present their novel computational methods that have engineering and physics applications

Performance of automotive air conditioning system using al2o3-sio2 nanolubricants

Enhancement in the coefficient of performance (COP) of the automotive air conditioning (AAC) system is necessary to reduce fuel consumption. A novel approach for improvement in refrigeration system performance is by dispersing nanoparticles in the conventional lubricant of AAC compressor. However, single-component lubricant applications contribute limitations on stability, compressor work, wear rates and AAC performance. The recent trend in nanoparticle dispersion technology is by utilizing two or more metal or metal oxide nanoparticles in existing lubricant and is known as composite nanolubricants. The composite nanolubricants is expected to improve the properties of single-component nanolubricants in achieving enhancement in thermal properties, rheological properties, stability, and AAC system performance. The aims of the present study are to evaluate the properties of metal oxide composite nanolubricants and to investigate the optimum condition of the AAC system performance using the best combination of composite nanolubricants. Metal oxide nanoparticles were dispersed in the Polyalkylene Glycol (PAG) 46 lubricant with different combinations of two types of nanoparticles using the two-step method of preparation. The composite nanolubricants was prepared up to 0.1% volume concentration with a variation of nanoparticle composition ratios. Thermal physical properties of different metal oxide composite nanolubricants were measured at temperatures of 30 to 80 °C. Then, the thermal physical properties of Al2O3-SiO2/PAG composite nanolubricants were measured with a variation of nanoparticle composition ratios and volume concentrations. Tribological properties of the composite nanolubricants were evaluated for different loads and speeds. The experimental investigation for the AAC performance was carried out using Al2O3-SiO2/PAG composite nanolubricants (best metal oxide combination) by varying the composition ratios and volume concentrations. Compound optimization technique using the Taguchi and Response Surface Methodology (RSM) methods were selected to optimize the AAC system. Stability evaluation showed Al2O3-SiO2/PAG composite nanolubricants having an excellent stability condition with no sedimentation observed within a month. It was proven by the measurement of the zeta potential up to 61.1 mV and maintenance of the concentration ratio of UV-Vis spectrophotometer of more than 90%. Thermal conductivity and dynamic viscosity of the composite nanolubricants increased with volume concentration and decreased with temperature. The tribological properties observation with optimal conditions of coefficient of friction (COF) and wear rates were found at 0.02% volume concentration. The COF and wear rates were reduced to 4.49% and 12.99%, respectively. The composite nanolubricants at 60:40 composition ratio was observed to be the most effective composition ratio and recommended by the properties evaluation of the nanolubricants. The maximum COP enhancement was achieved up to 28.10% with 0.015% volume concentration and 60:40 composition ratio of Al2O3-SiO2/PAG composite nanolubricants. Consequently, the AAC system parameter namely composition ratio, compressor speed, initial refrigerant charge, and volume concentrations of 60:40, 900 rpm, 155 g and 0.019% respectively were optimized using the compound optimization technique. The optimization results yield optimum cooling capacity, compressor work, COP, and power consumption of 0.94 kW, 19.20 kJ/kg, 9.05 and 0.62 kW, respectively, with highest desirability of 81.60%. Finally, it can be concluded that 0.019% is the optimum volume concentration for Al2O3-SiO2/PAG nanolubricant. Therefore, 0.019% Al2O3-SiO2/PAG with composition ratio of 60:40 was highly recommended for the optimum performance in AAC system

Enhanced heat transfer using oil-based nanofluid flow through conduits

The application of nanofluids for enhancing the heat transfer rate is widely used in various heat exchanger applications. The selection of oil as the base to prepare nanofluids significantly enhances the thermal performance, due to its high heat carrying capacity as compared to conventional base fluid. A review is performed of various heat exchanger conduits having base fluid as nanoparticles with oil. It is reported that the heat transfer rate of a heat exchanger is significantly increased with the use of oil-based nanofluids. The rate of heat transfer depends on the type of nanoparticle, its concentration and diameter, the base fluid, as well as factors like the mixture of more than two nanoparticles (hybrid nanofluids) and stability. A review is also performed of the thermal performance of the different nanofluids analyzed by various investigators. The heat transfer system reviewed in this work includes triangular, square, and circular conduits, as well as rib surface conduits. The review of various applications viz. solar thermal systems, heat exchangers, refrigerators, and engines, is carried out where the inclusion of the oil base is used. It is reported that the amalgamation of the nanomaterial with the oil as base fluid is a prolific technique to enhance thermal performance. The performance of the reviewed research work is comparatively analyzed for different aspects viz. thermal oil, mineral oil, hybrid, and conventional nanoparticles, concentration of nanoparticles, etc. The novelty of the present work is the determination of the effective performing oil-based nanofluid in various applications, to figure out the selection of specific mineral oil, thermal oil, nanoparticle concentration, and hybrid nanofluids.https://www.mdpi.com/journal/energiesam2023Mechanical and Aeronautical Engineerin