Nanofluid Concentration Research Articles

Experimental study of preparing the CoFe2O4 magnetic nanofluid and measuring thermal-fluid characteristics of the stabilized magnetocaloric nanofluid

The purpose of this study was to examine the rheological features of CoFe2O4 superparamagnetic nanoparticles dispersed in water-ethylene glycol (EG) coolant as the basis fluid. The experiments are carried out at temperatures between 10 and 50 degrees Celsius, with five mass fraction concentrations of magnetocaloric nanofluid as well as different shear rates. The solvothermal-produced cobalt ferrite metallic compounds are disseminated in EG-water (50:50) coolant. Evaluation of functional groups and organic compounds, the crystal structure of spinel ferrite, the size and morphology of nanoparticles, and the specific surface area, respectively, were carried out. For the developed magnetocaloric nanofluid, shear rate variation illustrates the non-Newtonian behavior of Bingham plastic. The results show that increasing the mass concentration of nanoparticles from 0.05 % to 0.8 % results in about 80 % increase in viscosity at 10 °C. Additionally, thermal conductivity has increased to a maximum of 9.4 % at 50 °C and is improved by increasing temperature.

Optimization of Nanofluid Concentration for Energy Intensification in Corrugated Plate Type Heat Exchanger

The overall heat transfer coefficient of the heat exchanger will improve with an increase in the flow rate and concentration of nanofluid. But beyond an optimum nanoparticle concentration, the overall effectiveness seems to decrease due to an increase in pressure drop that consequently leads to an increase in pumping power. The novelty of the present work is to find the optimum concentration of CuO-Water nanofluid that exhibits the optimum heat transfer rate and global minimum pumping power, using both experimental and numerical study. The cold nanofluid and hot water entered the counter currently at 303.15 and 333.15 K respectively in the corrugated plate heat exchanger. It was observed from the experimental and numerical results that the values of overall heat transfer coefficient and pressure drop were increased monotonically (454–710 W/(m2-K) and 6–133 Pa respectively), with the increment in the concentration and flow rates of the nanofluid. Because of this trend, it was challenging to figure out the optimum nanofluid concentration using these parameters. Later, a procedure was presented to obtain an optimum concentration of nanofluid, to reduce the hot stream temperature by 288.15 K. The hydraulic power exhibited a global minimum at an optimum concentration of 0.5 vol% of nanofluid.

Cattaneo-Christov Heat Flux Model for Bio-Convective Radiative Eyring-Powell Nanofluid with Viscous-Ohmic Dissipation and Magnetic Dipole Impacts

In this work we studied the solutions of the bio-convected Eyring-Powell nanofluid involving gyrotactic micro-organisms in the presence of viscous-ohmic dissipation, double diffusion, and magnetic field over a stretched sheet under the impacts of nonlinear radiation and Arrhenius activation energy. The magneto-nanoparticles suspension in microorganisms are beneficial in nanofluid stability. Also, they have number of applications in nanosciences, biotech, pharmaceuticals, and mechanical development. The nonlinear coupled PDEs are transformed into ODEs by taking a suitable set of similarity transformations and then computationally solved with MATLAB’s bvp4c and RK4-Shooting technique. The skin friction coefficient, Nusselt number, and Sherwood number are represented in tabular form. The mass and heat transmission rate improve in the presence of gyrotactic microorganisms. The temperature as well as concentration of Eyring-Powell Nanofluid get decreased by accelerating the significant mass and thermal stratification. The concentration profile Φ(η) depreciate for higher Chemical reaction rate (σ), Schmidt number (Sc), and temperature difference (δ1) parameters but rises upon increasing values of Activation energy (Ea). Also, the microorganism concentration difference parameter (β1), bioconvection Lewis number Lb and Peclet number Pe are opposing the motile microorganism density profile.

Influence of Silica Oxide Nanofluid for Different Concentrations on Photovoltaic Cell

Photovoltaic (PV) cells, a renewable fuel, are widely employed. A conventional PV cell also loses efficiency as the temperature rises. This research addresses this issue by cooling the PV cell with nanofluid, specifically SiO2 and distilled water. Applying SiO2 nanofluid experimentally using a real experimental setup is hoped to cool the PV cell’s surface as it becomes heated. This research aims to use distilled water and various concentrations of SiO2 nanofluid, such as 0.1 wt%, 0.2 wt%, and 0.3 wt% on Photovoltaic Cell and flow rate of 2 LPM and a radiation rate of 800 W/m2. ANSYS is used to confirm experimental results by using SiO2 as a nanofluid to lower the PV cell’s temperature and boost its thermal efficiency. The experiment’s findings demonstrated that utilizing nanofluid as a coolant boosted the PV cell’s thermal efficiency and decreased its temperature. Results showed that the thermal efficiency increased with the use of nanofluid as a coolant and with increasing mass concentration. Thermal efficiency values for distilled water, 0.1%, 0.2%, and 0.3% SiO2 were 35.56%, 79.91%, 91.04%, and 104.01%, respectively. This study also discovered that SiO2 works better in terms of cooling the PV cell than normal fluid because of its higher thermal conductivity. The experimental and numerical data show the same decline in PV cell surface temperature and thermal efficiency, unlike the computational results.

Comparative Study of Convective Oldroyd-B Nanofluid and Hybrid Nanofluid Flow, Heat and Mass Transfer Analysis Over Stretching Sheet with Cattaneo-Christov Heat Flux Model

The current analysis appraises the flow, heat and mass transfer characteristics of Oldroyd-B nanofluids SWCNT-Water and hybrid nanofluids SWCNT/MWCNT-Water over the stretching sheet. Thermal radiation, modified Fourier heat flux and convective boundary conditions are also used to evaluate the flow. Graphs are used to compare the characteristics of nanofluid SWCNT-Water and hybrid nanofluid SWCNT/MWCNT-Water nanofluids in terms of concentration, temperature, and velocity. The flow mechanism is modelled in the form of nonlinear system of partial differential equation. These PDEs are converted into Ordinary differential equations by using the similarity variable techniques. The Finite Element Method is pre-owned to solve the obtained ODEs. Plots are used to show the results of temperature, concentration and velocity for both nanofluids for various values of the relevant parameters. The dimensionless skin friction coefficient, Nusselt number and Sherwood number values are scrutinized and revealed in tabular form. The important findings of this study reveal that the scattering of temperature and concentration of both SWCNT-Water nanofluid and SWCNT/MWCNT-Water hybrid OBF nanofluid elevates with amplifying values of thermal retardation parameter. With increasing values of the power low index number the sketches of temperature and velocity are both attenuate in the fluid region.

Performance comparison of a solar parabolic trough concentrator using different shapes of linear cavity receiver

This study presents a numerical investigation of a solar Parabolic Trough Concentrator (PTC) with various Linear Cavity Receivers (LCRs). A linear trapezoidal cavity receiver was simulated and analyzed optically and thermally in the PTC system. The performance of the linear trapezoidal cavity receiver was assessed at two different angles: 25° and 55°. Optical and thermal simulations were conducted on a PTC system with a novel linear wounded tubular trapezoidal LCR. Subsequently, the optical and thermal performance of the PTC system was compared with alternative LCR shapes, namely cubical, V-shaped, trapezoidal 25°, and trapezoidal 55°. Additional contribution of the present study is to conduct energy and exergy analyses on the optimized solar PTC system employing a soybean oil-based-MXene nanofluid with varying concentrations (0 %, 0.025 %, 0.075 %, and 0.125 % weight). The findings indicate that all LCRs exhibit optimal cavity-absorbed heat flux and optical efficiency when aligned with the focal line. Moreover, the cubical and trapezoidal cavity receivers, when equipped with the ideal aperture width, demonstrate the highest and lowest performance, respectively. The most favorable exergy performance is achieved by employing the nanofluid concentration of 0.075 % weight at an inlet temperature of 55 °C at about 4 %. Also, the thermal efficiency of the solar system was calculated as about 82 % with the application of the nanofluid concentration of 0.075 % weight at an inlet temperature of 25 °C. The research findings offer valuable insights into enhancing the performance of the solar thermal system to generate more power for the implementation of the 7th development plan in Iran.

Stochastic supervised networks for numerical treatment of Eyring–Powell nanofluid model with Darcy Forchheimer slip flow involving bioconvection and nonlinear thermal radiation

The aim of this study is to estimate the solution of Eyring–Powell nanofluid model (EPNFM) with Darcy Forchheimer slip flow involving bioconvection and nonlinear thermal radiation by employing stupendous knacks of neural networks-based Bayesian computational intelligence (NNBCI). A dataset for the designed NNBCI is generated with Adam numerical procedure for sundry variations of EPNFM by use of several variants including slip constant, Schmidt number, mixed convection parameter, Prandtl number, and bioconvection Lewis parameter. Numerical computations of various physical parameters of interest on EPNFM are estimated with artificial intelligence-based NNBCI and compared with reference data values generated with Adam’s numerical procedure. The accuracy, efficacy, and convergence of the proposed NNBCI to successfully solve the EPNFM are endorsed through M.S.E, statistical instance distribution studies of error-histograms, and assessment of regression metric. The proposed dataset exhibits a close alignment with the reference dataset based on error analysis from level E[Formula: see text] to E[Formula: see text] authenticates the precision of the designed procedure NNBCI for solving EPNFMs. The executive and novel physical importance of parameters governing the flow, such as nanofluid velocity, temperature, and concentration profiles, are discussed. The observations imply that the presence of the slip constant, mixed convection parameter and Lewis number influences the velocity of the nanofluid. However, it is observed that temperature of the nanofluid declines for higher values of Prandl number while the concentration of nanofluid improves with increasing values of Schmidt number.

Heat Transfer and Fluid Flow Characteristics in a Micro Heat Exchanger Employing Warm Nanofluids for Cooling of Electronic Components

The heat transfer enhancement and hydrodynamic characteristics of nanofluid use in a micro heat exchanger is investigated for cooling electronic components working in hot climatic conditions. The cooling fluid employed was water and TiO2 nanoparticles at mass concentrations of 1% and 5%, the Reynolds numbers ranged from 400 to 2000, and the inlet temperatures ranged between 35 °C and 65 °C. At a nanofluid inlet temperature of 55 °C and a nanoparticle concentration of 1%, the Nusselt number increased by 23% up to 54% as the Reynolds number varied between 400 and 2000. At a nanoparticle concentration of 5%, the percentages that correspondingly enhanced the Nusselt number were 32% and 63%. The temperature of the electronic heating component decreased by 4.6–5.2 °C when the nanofluid concentration was increased from 0 to 5% at a Reynolds number of 400 and a nanofluid inlet temperature of 35 °C. Small increments in the pressure drop of about 6% and 13% were observed at nanofluid concentrations of 1% and 5%, respectively. With nanoparticle concentrations of 1% and 5%, a Reynolds number of 2000, and a nanofluid inlet temperature of 35 °C, performance evaluation criterion (PEC) values of 1.36 and 1.45 were obtained. When the nanofluid inlet temperature increased to 65 °C, the PEC parameter decreased to 1.02–1.10 for both concentrations.

Improving sensible heat storage in a vertical annular pipe subject to variable inlet boundary condition using TiO2/water nanofluid: Numerical study

A computational fluid dynamics (CFD) analysis is conducted to investigate the thermal performance of unsteady free convection of TiO2/water nanofluids. The study process within a coaxial heat exchanger system. The model is based on the mixture Buongiorno approach. Due to the axisymmetric conditions, the study is carried out in two dimensions, and the conservation equations are reformulated in dimensionless form. The obtained PDE system is Discretized using the finite element method. The TiO2 concentration heterogeneity, resulting from thermophoresis and Brownian motion is considered. The presentation of the results encompassed isotherms, nanoparticle volume fraction distributions, and streamlines. The validation of the model shows a good agreement with the experimental results. The impact of the mass fraction’s nanoparticles ( 0.01 ≤ ϕ ≤ 0.04 ) and the Rayleigh number ( 10 3 ≤ Ra ≤ 10 8 ) on the heat transfer performance are analyzed. The parametric study shows that an increase in the Rayleigh number has no effect on heat transfer enhancement. Unlike for Ra = 10 6 where an increase in Nusselt number is observed. It was found also that the effect of nanofluid concentration on the Nusselt number was more noticeable in high Rayleigh cases due to the convection-driven heat transfer.

The reversal of carbonate wettability via alumina nanofluids: Implications for hydrogen geological storage

Underground hydrogen storage (UHS) has been recognized as a key enabler of the industrial-scale implementation of a hydrogen-based economy. However, the efficiency and storage capacity of hydrogen (H2) in carbonate aquifers can be influenced by the presence of organic acids. Nevertheless, the existing literature contains few investigations of H2/calcite/brine wettability and the influence of organic acids on H2 storability in carbonate reservoirs. Therefore, the present study examines the influence of stearic acid on the dynamic H2/brine wettability of calcite substrates (as a proxy of carbonate formation) under various geological conditions (0.1–20 MPa at 323 K), equilibrated in 10 wt% NaCl brine. In addition, the application of various alumina nanofluid concentrations (0.05, 0.1, 0.25, and 0.75 wt%) is evaluated under the same experimental conditions for enhancing the organic-aged calcite wettability. The results demonstrate a significant impact of stearic acid on the dynamic (advancing and receding) contact angles of the calcite substrates, thereby resulting in a shift from intermediate water-wet to H2-wet conditions, representing an unfavorable state for H2 geological storage. Conversely, the application of alumina nanofluid on the organic-aged calcite substrate enhances the H2/brine/calcite wettability towards an intermediate water-wet state, which is more favorable for H2 residual trapping in carbonate formations. The optimal concentration of alumina nanofluid for the wettability modification of the organically aged calcite samples is found to be 0.25 wt%. These findings highlight the influence of organic acid contamination and the potential of alumina nanofluid application in enhancing H2 geo-storage conditions in carbonate reservoirs.

Simulation of the integration of PVT and TEG with a cooling duct filled with nanofluid

Recognizing the pivotal role of the cooling method in enhancing Photovoltaic-Thermal (PVT) efficiency, this study delves into the combined application of two innovative techniques: a finned tube and a confined jet. Additionally, the integration of a TEG (Thermoelectric Generator) is introduced to amplify output power. The improvement in cooling efficiency is achieved through infusing a composite of Carbon Nanotubes (CNT) and Fe3O4 into the coolant. The investigation encompasses three distinct cooling system configurations: 1) the base case employing a conventional pipe, 2) a system with a finned-tube cooling unit, and 3) a setup combining a confined jet with a finned tube. The introduction of hybrid nanoparticles results in an overall performance boost of around 2.64 % compared to the base case. Furthermore, the efficacy of the nanofluid concentration (φ) in the base case surpasses that of the Finned Jet case by a factor of 3.86. Notably, an increase in irradiance magnitude and jet inlet velocity contributes to a commendable enhancement in thermal performance, registering approximately 8.66 % and 3.48 %, respectively. The incorporation of fins and confined jets yields substantial improvements, resulting in an 86.13 % enhancement in TEG performance and a commendable 26.42 % rise in thermal performance.

Simulation of hybrid boiling nano fluid flow with convective boundary conditions through a porous stretching sheet through Levenberg Marquardt artificial neural networks approach

In the domain of artificial neural networks, the Levenberg-Marquardt technique stands out for its innovative approach and convergent stability. It generates a numerical approach for the progression of a hybrid Cu–Al2CO3/water nanofluid on a porous stretched sheet (HNF-PSS), employing regression plots, state transition measures, histogram representations, and mean squared errors. This work explores the analysis of the fluid flow problem associated with HNF-PSS, introducing a novel application of an intelligent computing system that utilizes the effectiveness of neural networks trained by the Levenberg-Marquardt algorithm (NN-TLMA). The initial mathematical expression, expressed in terms of partial differential equations (PDEs) for HNF-PSS, undergoes transformation into dimensionless nonlinear ordinary differential equations (ODEs). The collection of data for the envisioned NN-TLMA involves parameters influencing the velocity of the HNF-PSS system model, generated using the Lobatto IIIa formula. The efficacy of the suggested NN-TLMA for solving the HNF-PSS is robustly verified by examinations of state transition dynamics, regression analyses, mean square error, and error histogram studies. The consistent alignment of the obtained results with corresponding solutions attests to the legitimacy of the structure, achieving a high level of accuracy within the range of 10–6 to 10–8. Insightful findings demonstrate that the thermal Biot number contributes significantly to an upsurge in fluid temperature. Furthermore, an augmentation in nanofluid concentration and thermal profile is found to increase the porosity strength of the medium. Nevertheless, an attenuation in the velocity profile is noted under these conditions. The application of this simulation work can be found in optimizing the designs of heat exchanger, in biomedical application and in renewable energy processes.

The influence of using MWCNT/ZnO-Water hybrid nanofluid on the thermal and electrical performance of a Photovoltaic/Thermal system

Rising photovoltaic panel temperatures significantly compromise their performance and lifespan, leading to lower power output and conversion efficiency. Consequently, research on PV panel cooling strategies has gained momentum to address these challenges. This study presents an experimental investigation of a photovoltaic/thermal system's performance using a cooling fluid – a multi-walled carbon nanotube/zinc oxide nanofluid. A comparative analysis is conducted on three PV panels: uncooled, water-cooled, and nanofluid-cooled. Notably, our experiment employed a low mass flow rate (0.156 kg/min), significantly lower than typical values reported in prior literature, and a 0.1 wt% nanofluid concentration. Our primary objective was to evaluate the efficacy of MWCNT/ZnO nanofluid in enhancing the thermal management and overall efficiency of a PVT system. This study focused on the impact of nanofluid on electrical efficiency, thermal efficiency, and exergy performance of the system. The results demonstrate significant improvements. The key findings of this investigation reveal that MWCNT/ZnO nanofluid effectively improves the base fluid's thermal properties, leading to substantial enhancements in both electrical and thermal efficiencies of the PVT system. Compared to the uncooled panel, the nanofluid achieved a maximum temperature reduction of 14.9 °C on the panel surface, a 16.8 % increase in average electrical efficiency, and a maximum thermal efficiency of 51.3 % compared to 45.5 % for water cooling. Moreover, the average overall efficiency of the system with nanofluid cooling reached 58.7 %. Furthermore, the implementation of MWCNT/ZnO nanofluid cooling resulted in a significant boost in maximum overall exergy efficiency, surpassing water cooling and conventional systems by 7 % and 27 %, respectively. Additionally, a 3.5 % reduction in entropy generation and exergy destruction was observed compared to the conventional system.

Enhancing high-speed CNC milling performance of Ti6Al4V alloy through the application of ZnO-Ag hybrid nanofluids

Abstract This research investigates the performance of high-speed CNC milling operations on Ti6Al4V alloy by employing a novel ZnO-Ag hybrid nanofluid. The study involves the preparation and characterization of nanofluids with varying concentrations of nanoparticles, focusing on thermal conductivity and stability. The machining experiments encompass four critical input parameters: Minimum Quantity Lubrication (MQL) flow rate, cutting speed, nanofluid concentration, and feed rate. Performance evaluation is based on average surface roughness (Ra) and cutting temperature. Key findings include a remarkable 21.05% improvement in thermal conductivity for the ZnO-Ag-based sunflower oil at 0.2% volume concentration compared to 0.05% concentration. The prepared nanofluids exhibit good stability. Moreover, cutting speed and MQL flow rate emerge as significant contributors to Ra, accounting for 35.62% and 34.82%, respectively. Interestingly, MQL flow rate is identified as the most influential factor, surpassing even cutting speed. SEM images for tool wear reveals that the ZnO-Ag based sunflower oil reduced tool wear significantly. In conclusion, the proposed ZnO-Ag-based sunflower oil at 0.2% concentration emerges as the good option for sustainable high-speed machining of Ti6Al4V alloy, showcasing

Synergistic effects of electric and magnetic nanoparticles with electromagnetic energy in enhanced oil recovery

This study investigates the effect of electromagnetic energy implementation in the use of electric, magnetic, and hybrid nanofluids for enhanced oil recovery. The challenge lies in comprehending the intricate interplay of these factors to enhance the recovery factor (RF) of oil. We conducted a comprehensive analysis of parameters influencing oil recovery at its primary, secondary, and tertiary stages using finite-element-based simulations. Transitioning to the secondary stage, we observe a positive correlation between increasing brine flow rates and heightened RF. In the tertiary stage, a comparative assessment of nanofluids, including magnetite (Fe3O4), zinc oxide (ZnO), and copper oxide (CuO), reveals that enhancing nanofluid concentrations up to 0.001 % positively impacts RF, with Fe3O4 leading the pack at 22.20 %, followed by ZnO at 21.00 %, and CuO at 11.02 %. The introduction of electromagnetic field consistently augments RF for all nanofluids by a minimum of 4.8 %. Furthermore, this study explores the effect of hybrid nanofluids on RF, which tend to exhibit lower RF values. However, the introduction of electromagnetic energy significantly enhances RF for all hybrid nanofluids. The study offers valuable insights into the potential of nanomaterials and electromagnetic methods in the oil and gas industry.

Influence of the twisting and nano fluids on performance of a triangular double tube heat exchanger

Abstract The hydraulic and thermals performance of flow in a double-tube heat exchanger with an inner twisted triangle tube of length L = 1 m has been studied numerically. Equations for energy, turbulence, and Navier–Stokes were used to model the fluid flow and heat transfer in a double-tube heat exchanger with an inner twisted triangle tube. The Reynolds number range was 5000–30,000 for nanofluid (water-Al2O3) as a working fluid under a turbulent flow regime. The considered configuration was examined by varying the volume concentration of nanofluid while keeping the twist ratio constant (Tr = 5). Different cases of volume concentration of nanofluid are triggered (0.05 %, 1 %, 2.5 %, and 4 %, respectively). The numerical outcomes of a double-twisted tube heat exchanger with an inner triangle-twisted tube are validated with the obtainable numerical data. The governing equations were solved with ANSYS Fluent 18.2. The findings reveal that the larger volume concentration of nanofluid (4 %) gives a greater Nusselt number and vice versa due to the increased thermal conductivity of the nanofluid in the double twist tube heat exchanger compared with a plain tube. However, the nanofluid Nusselt number grows with the rise of both the Reynolds number and volume concentration (Ø), and the best value of the Nusselt number is 210 when Reynolds number = 30,000 and Ø = 4 %. The effectiveness of the heat exchanger grows with an increase in the concentration of the nanofluid and a reduction in the torsion ratio compared to the normal tube. The effectiveness of the double-tube heat exchanger with an inner twist triangle tube increases to the highest value of 0.38 at Reynolds 30,000 and Ø = 4 %.

Parametric study on thermal performance augmentation of TiO2/water nanofluids flowing a tube contained with dual counter twisted-tapes

The study of compound heat transfer enhancement technique using dual counter twisted tapes (DCTs) together with TiO2/water nanofluids was carried out. The dual twisted tapes in form of counter-swirl tape arrangement were utilized at three twist ratios (y/w = 1.5, 2.0 and 2.5). TiO2/water nanofluids having three different volume concentrations (φ = 0.05, 0.10 and 0.15 %) were employed as the testing fluids. The results indicated that heat transfer rate, friction factor and thermal enhancement index rose with decreasing tape twisted ratio and elevating nanofluid concentration. The TiO2/water nanofluids applied in the present work offered higher Nu than pure water (the base fluid) by 7.3–10.0 %. The application of DCT with the smallest y/w of 1.5 and TiO2/water nanofluids with the largest φ of 0.15 vol% led to the highest thermal enhancement index (TEI) of 1.53, under the same pumping power criteria. Additionally, the k-nearest neighbor (k-NN) and artificial neural network (ANN) were developed to predict the thermal enhancement index (TEI). It was found that the k-NN and ANN models provided maximum R2 values of 0.919 and 0.992 f, respectively.

Two-phase simulation of hydrothermal performance and entropy generation aspects of a biologically prepared nanofluid-cooled heat sink with helical Tesla valve-based microchannels

The continuous development of innovative cooling techniques is imperative for advancing electronic device performance, enhancing efficiency, and prolonging their operational reliability in an ever-evolving technological landscape. In this numerical investigation, the hydrothermal performance and entropy generation aspects of a heat sink featuring Tesla valve-base helical channels are explored using the two-phase mixture method. The chosen heat transfer fluid is a water-silver nanofluid synthesized through a biological method. The study delved into the impact of Reynolds number (Re = 500–2000) and nanofluid concentration (φ = 0–1%) on the system's functional parameters, and the results are subsequently compared with data associated with a heat sink employing the helical plain channels. It was uncovered that elevating Re and diminishing φ result in improved central processing unit (CPU) cooling, lowered thermal resistance, and a reduction in the temperature differential between the maximum and minimum CPU temperatures. Meanwhile, the pumping power of nanofluid increases with higher Re s and lower φ s. Furthermore, it was discovered that the overall hydrothermal performance of the heat sink with Tesla valve-type helical channel consistently surpasses that of the heat sink with helical plain channel. The peak value of the Performance Evaluation Criterion, reaching 1.642, was associated with Case Re = 500 &φ = 0 %. Furthermore, it was found that substituting the Tesla valve-base channel for the plain channel results in a decrease in the total entropy generation up to a Re of 1500.

Microfluidic flow synthesis of Al2O3 nanofluids for efficient phase-change boiling heat transfer enhancement of electronic devices

Integrating microchannel flow boiling heat transfer with nanofluids is an effective method for cooling electronic devices. However, traditional methods have significant limitations in achieving facile synthesis of nanofluids with desirable properties. In this study, we propose a straightforward synthesis strategy using microfluidic reactors, which enables continuous and high-throughout synthesis of Al2O3 nanofluids with high purity and long-term stability. These nanofluids were found to enhance boiling heat transfer performance by delaying bubbles coalescence, increasing surface nucleation sites, improving the nucleation rate, and enhancing wettability by observation of the bubble behavior. Specifically, the critical heat flux (CHF) and corresponding heat transfer coefficient (HTC) are increased by a maximum of 32 % and 26 %, respectively, with negligible change in pressure drop. Moreover, the heat transfer performance deteriorates with increasing concentration of alumina nanofluids. These findings not only provide guidance of microchannel flow boiling with nanofluids, but also present valuable insights for the application of nanofluids in two-phase cooling systems for electronic devices.

Experimental Investigation for Enhancement of Heat Transfer Coefficient in Car Radiator by Using Multiwall Carbon Nanotube (MWCNT) Nanofluid

Improving heat transfer coefficient is a significant subject of study in many engineering domains. The use of nanofluids in car radiators might boost the heat transfer coefficient. The current study investigates a car's radiator's heat transfer coefficient and thermal conductivity. The heat transmission parameters of a car radiator were analyzed for coolant mass flow rates ranging from 600 to 1200 liters/hour and nanofluid concentrations ranging from 0.2 to 0.8% by volume. The primary coolant was prepared by combining water and ethylene glycol in a 60:40% combination with multi-walled carbon nanotube nanoparticles. The coolant's input temperatures were varied between 30 °C and 80 °C by impinging an air jet into the car radiator through a hallow cone nozzle plate with and without spacing. The result demonstrates that the volume flow rate of coolant on the tube side increases considerably as the heat transfer coefficient increases. At a nanoparticle concentration of 0.8 vol. %, the nanofluid's total heat transfer coefficient is enhanced by 12% compared with the base fluid. The heat transfer coefficient is improved by 42.6% for 0.8% volume of MWNCT nanofluid without spacing of the hallow cone nozzle plate and by 51.9% with spacing of the hallow cone nozzle plate.