Graphene Nanofluids Research Articles

Thermophysical Profile of Industrial Graphene Water-Based Nanofluids.

The exceptional properties of high-grade graphene make it an ideal candidate for thermal dissipation and heat exchange in energy applications and nanofluid development. Here, we present a comprehensive study of few-layer graphene (FLG) nanofluids prepared in an industrial context. FLG nanofluids were synthesized through an ultrasound-assisted mechanical exfoliation process of graphite in water with a green solvent. This method produces FLG of high structural quality and stable nanofluids, as demonstrated by electron microscope, dynamic light scattering and ζeta potential analyses. Thermal conductivity measurements of FLG-based nanofluids were conducted in the temperature range of 283.15 K to 313.15 K, with FLG concentrations ranging from 0.005 to 0.200% in wt. The thermal conductivity of FLG nanofluids is up to 20% higher than water. The modeling of nanofluid thermal conductivity reveals that this enhancement is supported by the influence of the thermal resistance at the FLG interface, and the content, average dimensions and flatness of FLG sheets; this latter varying with the FLG concentration in the nanofluid. Additionally, the density and heat capacity of FLG suspensions were measured and compared with theoretical models, and the rheological behavior of FLG nanofluids was evaluated. This behavior is mainly Newtonian, with a weak 5% viscosity increase.

Comparative study for heat transfer characteristics of many graphene hybrid nanofluids flow over a shrinking sheet

In this work, steady two-dimensional boundary layer flow of an electrically conductive hybrid nanofluids past a shrinking sheet, along with magnetic field, thermal radiation, suction/injection, heat source/sink and velocity slip model, has been investigated. Particularly, eight mixed hybrid graphene nanofluids of copper, silver, aluminium oxide and titanium dioxide were studied and compared with the classical graphene–water nanofluid. Appropriate similarity transformations have been used to convert the governing PDEs into a set of non-linear ODEs, then, we deduced exact solutions of the flow and temperature. In addition, possibility of obtaining no, unique and dual solutions for these functions were introduced as critical values and regions via graphs. Moreover, validation of the present solutions with those in the literature has been tabulated. Furthermore, asymptotic expression and local extremum for the most important equation were studied.On comparing with those results in the literature at some special values of the included parameters, excellent agreements were gotten. It was mentioned that two conditions have to be simultaneously applied to result the temperature dual solution with restrictions on choosing values of specific parameters. Further, in the injection case, the temperature distributions are larger by about 66.7% on comparing with those in the suction case, for all almost the investigated parameters. To get the highest temperature, it was deduced that the copper is to be firstly added to the water and then mixed with the graphene to produce the hybrid nanofluid. Graphene–copper/water employs as a heater on increasing the Eckert number, shrinking parameter and second velocity slip (for N<0). Furthermore, it acts as cooler with an increase of magnetic field, |heat source/sink parameter|, suction/injection parameter, solid volume fraction, first velocity slip and second velocity slip (for N>0).

Influence of graphene nanoplatelets dispersion in food graded heat transfer fluid on the performance of Non-Centrifugal cane sugar unit- a CFD approach

Non-centrifugal cane sugar unitusing food-grade heat transfer oils to make excellent jaggery is an emerging technology. Thermophysical characteristics of such fluids are crucial for improving the system’s efficiency. Graphene nanoplatelets with low weight concentrations are dispersed into Sigma-thermic fluid (STF) to prepare nanofluids which is utilized as heat transfer oils in the NCCS unit. To envisage the potential of these fluids a numerical model is developed by validating the experimental results of STF. Firstly, experiments with STF at 20 lpm, 433 K, were conducted in the NCCS unit, which was fabricated in the laboratory. The results are agreed with the error of 1.14 %; further, the developed numerical model is employed to envisage the potential of STF based graphene nanofluids. Morphological graphene studies are conducted, and nanofluids with different weight concentrations are subsequently prepared. Experimentally measured nanofluid thermophysical characteristics are employed in the numerical model. Simulations are run until the bowl inner surface achieves concentrated sugar cane juice temperature. The effect of inlet temperature and concentration of nanoparticles on the sugar cane juice boiling time, bowl inner surface temperature, heat transfer rate, performance index ratio, thermohydraulic performance, and entropy generation is investigated. The results show that the Nusselt number increases with temperature, and the Nusselt number enhanced by 13.48 %, 22.18 %, and 30.09 % at temperatures of 413 K, 423 K, and 433 K, respectively compared to 403 K temperature for GrS0.3 %. Moreover, heat transfer is enhanced by 22.17 % with GrS0.3 % nanofluid compared to base fluid (STF) in the shortest duration, i.e., 7767 s. As the intake fluid temperature rises from 403 K to 413 K, 423 K, and 433 K, fluid friction irreversibilities are 13 %, 20 %, and 25 %.

Linear stability analysis of micropolar nanofluid flow across the accelerated surface with inclined magnetic field

PurposeThe purpose of this paper is to study the two-dimensional micropolar fluid flow with conjugate heat transfer and mass transpiration. The considered nanofluid has graphene nanoparticles.Design/methodology/approachGoverning nonlinear partial differential equations are converted to nonlinear ordinary differential equations by similarity transformation. Then, to analyze the flow, the authors derive the dual solutions to the flow problem. Biot number and radiation effect are included in the energy equation. The momentum equation was solved by using boundary conditions, and the temperature equation solved by using hypergeometric series solutions. Nusselt numbers and skin friction coefficients are calculated as functions of the Reynolds number. Further, the problem is governed by other parameters, namely, the magnetic parameter, radiation parameter, Prandtl number and mass transpiration. Graphene nanofluids have shown promising thermal conductivity enhancements due to the high thermal conductivity of graphene and have a wide range of applications affecting the thermal boundary layer and serve as coolants and thermal management systems in electronics or as heat transfer fluids in various industrial processes.FindingsResults show that increasing the magnetic field decreases the momentum and increases thermal radiation. The heat source/sink parameter increases the thermal boundary layer. Increasing the volume fraction decreases the velocity profile and increases the temperature. Increasing the Eringen parameter increases the momentum of the fluid flow. Applications are found in the extrusion of polymer sheets, films and sheets, the manufacturing of plastic wires, the fabrication of fibers and the growth of crystals, among others. Heat sources/sinks are commonly used in electronic devices to transfer the heat generated by high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light-emitting diodes to a fluid medium, thermal radiation on the fluid flow used in spectroscopy to study the properties of materials and also used in thermal imaging to capture and display the infrared radiation emitted by objects.Originality/valueMicropolar fluid flow across stretching/shrinking surfaces is examined. Biot number and radiation effects are included in the energy equation. An increase in the volume fraction decreases the momentum boundary layer thickness. Nusselt numbers and skin friction coefficients are presented versus Reynolds numbers. A dual solution is obtained for a shrinking surface.

Harnessing solar power: Innovations in nanofluid-cooled segmented thermoelectric generators for exergy, economic, environmental, and thermo-mechanical excellence

Addressing the imperative need for advancements in thermoelectric generation, this study pioneers an analysis of nanofluid-cooled solar segmented thermoelectric generators with non-uniform cross-sections. Insights into thermal management, structural integrity, and economic efficiency in thermoelectric systems are provided, employing a numerical model that accurately represents thermoelectric effects by accounting for temperature dependencies of semiconductor materials. Through research, exploration of diverse coolant strategies, including TiO2, Fe3O4, Al2O3, and graphene, offers key insights into their impact on cooling dynamics. Findings demonstrate that graphene nanofluid, operating at a flow velocity of 2 m/s, outperforms others, achieving optimal power generation of 221.77 mW and an exergy efficiency of 8.99 %. Additionally, at a concentrated irradiance of 595 kWm−2, graphene leads in environmental benefits, with the highest CO2 savings of 0.38 kgyr−1, and demonstrates economic advantages with a cost-effective dollar per mW value of 3.79×10−6 $mW−1. Furthermore, the study verifies the structural integrity of these systems, with graphene achieving an optimal von Mises stress of 1.35 GPa at a semiconductor height of 0.2 mm. These advancements contribute to environmentally friendly and high-performance generators for sustainable energy solutions, paving the way for future innovations in thermoelectric technology.

Experimental investigation of nanofluid lubrication on surface roughness under MQL aluminum alloy 6061-T6 series in drilling

PurposeThis study aims to investigate the impact of varying the number of minimum quantity lubrication (MQL) nozzles, wind pressure, spindle speed and type of lubrication on surface roughness, fatigue life and tool wear in the drilling of aluminum alloy 6061-T6.Design/methodology/approachThe effect of using different lubricants such as palm oil, graphene/water nanofluid and SiO2/water in the MQL method was compared with flood and dry methods. The lubricant flow and feed rate were kept constant throughout the drilling, while the number of nozzles, wind pressure and spindle speed varied. After preparing the parts, surface roughness, fatigue life and tool wear were measured, and the results were analyzed by ANOVA.FindingsThe results showed that using MQL with four nozzles and graphene/water nanofluid reduced surface roughness by 60%, followed by SiO2 nanofluid at 56%, and then by palm oil at 50%. Increasing the spindle speed in MQL mode with four nozzles using graphene nanofluid decreased surface roughness by 52% and improved fatigue life by 34% compared to the dry mode. SEM results showed that tool wear and deformation rates significantly decreased. Increasing the number of nozzles caused the fluid particles to penetrate the cutting area, resulting in improved tool cooling with lubrication in all directions.Originality/valueNumerous attempts have been made worldwide to eliminate industrial lubricants due to environmental pollution. In this research, using nanofluid with wind pressure in MQL reduces environmental impacts and production costs while improving the quality of the final workpiece more than flood and dry methods.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0021/

Heat transfer inside annular passages: A comparison of non-circular and fully circular passages using eco-friendly graphene nanofluid

This research investigates the thermal performance of an annular passage using eco-friendly nanofluids as substitutes for conventional working fluids. Specifically, the study focuses on the utilization of covalently functionalized Graphene Nanoplatelets (GNPs) dispersed in an aqueous medium, with Gallic acid as the functionalizing agent. Nanofluids were synthesized at different weight concentrations (0.1 wt%, 0.05 wt%, and 0.025 wt%) and exhibited an excellent long-term colloidal stability for 39 days, with a relative concentration of 94.4% at 0.025 wt%. Thermophysical property evaluations revealed significant enhancements of 18.25% and 8.23% in thermal conductivity and viscosity, respectively at 0.1 wt%. The nanofluids exhibited average enhancements of convection heat transfer coefficient evaluations indicating improved thermal performance for GaGNPs/DW nanofluids, with the highest average enhancement of approximately 12.11% achieved at 0.1 wt%. To investigate the impact of different annular geometries, a numerical study (CFD) was conducted. Various inner rod shapes, including circular, rectangular, square, triangular, and pentagonal, were considered. The pentagonal cross-section exhibited the highest average increase in convection heat transfer coefficient at 13.9%, followed by rectangular and triangular shapes. In a numerical case study with different thermal boundary conditions, the circular inner rod shape demonstrated the highest thermal performance at 0.1 wt%.

Honeycomb-configured dissipative nanofluid flow within a squeezed channel with entropy generation: regression and numerical evaluations

PurposeNanosized honeycomb-configured materials are used in modern technology, thermal science and chemical engineering due to their high ultra thermic relevance. This study aims to scrutinize the heat transmission features of magnetohydrodynamic (MHD) honeycomb-structured graphene nanofluid flow within two squeezed parallel plates under Joule dissipation and solar thermal radiation impacts.Design/methodology/approachMass, energy and momentum preservation laws are assumed to find the mathematical model. A set of unified ordinary differential equations with nonlinear behavior is used to express the correlated partial differential equations of the established models, adopting a reasonable similarity adjustment. An approximate convergent numerical solution to these equations is evaluated by the shooting scheme with the Runge–Kutta–Fehlberg (RKF45) technique.FindingsThe impression of pertinent evolving parameters on the temperature, fluid velocity, entropy generation, skin friction coefficients and the heat transference rate is explored. Further, the significance of the irreversibility nature of heat transfer due to evolving flow parameters are evaluated. It is noted that the heat transference rate performance is improved due to the imposition of the allied magnetic field, Joule dissipation, heat absorption, squeezing and thermal buoyancy parameters. The entropy generation upsurges due to rising magnetic field strength while its intensification is declined by enhancing the porosity parameter.Originality/valueThe uniqueness of this research work is the numerical evaluation of MHD honeycomb-structured graphene nanofluid flow within two squeezed parallel plates under Joule dissipation and solar thermal radiation impacts. Furthermore, regression models are devised to forecast the correlation between the rate of thermal heat transmission and persistent flow parameters.

Radial basis Neural Network Model to Prediction of Thermal Resistance and Heat Transfer Coefficient of Oscillating Heat Pipe Using Graphene and Acetone-Based Nanofluids

Radial basis Neural Network Model to Prediction of Thermal Resistance and Heat Transfer Coefficient of Oscillating Heat Pipe Using Graphene and Acetone-Based Nanofluids

Numerical Investigation of PV/T System by Using Graphene Based Nanofluids

The effective use of solar radiation can be maximized by the implementation of a novel hybrid device referred to as a photovoltaic thermal collector (PV/T), which has the capability to simultaneously generate both electrical and thermal energy. As temperature increases, the efficiency of the photovoltaic (PV) cell drops. The present work employs graphene nanofluids as a means to decrease the temperature of the system in order to evaluate the photovoltaic thermal (PV/T) performance. The PV/T system is subjected to Computational Fluid Dynamics (CFD) simulation, wherein graphene nanofluids of different volume concentrations (0%, 0.1%, 0.2%, and 0.3%) and mass flow rates (0.065, 0.075, and 0.085 kg/s) are employed. The PV/T system demonstrated enhanced performance as a result of the implementation of the proposed approach, which effectively reduced the temperature of the solar cell during the period of maximum solar radiation, spanning from 9 AM to 4 PM. The utilization of the system was employed for the generation of thermal and electrical energy due to its respective thermal and electrical efficiency of 67% and 11.5%. The completed research has demonstrated that the integration of graphene nanofluids has the potential to enhance the efficiency of PV/T systems.

Study of Heating and Evaporation of Rotating Graphene Nanofluid under the Influence of Solar Radiation

Study of Heating and Evaporation of Rotating Graphene Nanofluid under the Influence of Solar Radiation

Numerical simulation study of boiling Critical Heat Flux characteristics of graphene nanofluids

IVR-ERVC (In-Vessel Retention – External Reactor Vessel Cooling) is a critical accident management method for ensuring the integrity of the reactor pressure vessel (RPV) lower head. One of the most crucial aspects within this method is to enhance the CHF (Critical Heat Flux) on the outer surface of the reactor pressure vessel (RPV) lower head. This paper explores the application of graphene nanofluids in IVR-ERVC. This paper uses computational fluid dynamics to numerically simulate the CHF characteristics of graphene nanofluids under different undercooling, mass flow rate, concentration, tilt angle, and gap size conditions and analyzes the impact of different factors on CHF and the coupling effects between different factors. The undercooling range is 5 K–100 K, the mass flow rate range is 150 kg/(m2∙s) to 3000 kg/(m2∙s), the concentration range is 0–1%, the inclination angle range is 0°–90°, and the gap sizes are 10 mm and 20 mm. The results show that the CHF can be effectively improved by adding nano-graphene into the base solution, and the CHF increases with the increase of subcooling degree, mass flow rate, concentration, dip Angle and gap size. Within the simulation range, the strengthening effect on CHF weakens when raising the undercooling and mass flow rate. And the larger the concentration and inclination angle within the simulation range, the better the enhancement effect on CHF. The maximum increase was 290%, while the average increase was 75.6%.This article studies the coupling effects between different parameters through numerical simulation. It can be concluded that increasing the mass flow rate weakens the enhancement of subcooling and concentration on CHF, increasing the subcooling weakens the enhancement effect of mass flow rate and concentration on CHF, and increasing the concentration enhances the enhancement effect of subcooling and mass flow rate on CHF. Enhance the mass flow rate will weaken tilt angle effect, while increasing the concentration will enhance the strengthening effect of tilt angle on CHF.

Design and tribological performance of graphene nanofluids dispersed by dragging effect of bicomponent gelator

Nanofluids have excellent lubrication and high thermal conductivity. However, the agglomeration and sedimentation produced by the large surface energy of nanoparticles in base liquid threaten the long-term dispersion stability and impact the wide application of nanofluid. In this work, based on the self-assemble behavior and continuous network structure formed by low molecular weight organic gelator, the uniform clusters were formed through regulating the kinetics behavior in the gelling process. The dragging effect was demonstrated by oleic acid - sodium dodecyl sulfate (OA-SDS) bicomponent gelator and graphene oxide (GO) nanosheets. The results showed that GO nanofluids dispersed by OA-SDS were stable for more than 12 months. The well-dispersed GO nanofluid exhibited better anti-friction and anti-wear properties under both immersion and electrostatic minimum quantity lubrication conditions. Moreover, the lower contact angle, surface tension and droplet size of nanofluids after charging improved the wettability on the frictional interface. The GO adsorption film formed on the friction interface protected the tribochemical reaction film of iron oxide and prevented the occurrence of sintering of base oil.

Effect of Variable Viscosity on Entropy Generation Analysis Due to Graphene Oxide Nanofluid Convective Flow in Concentric Cylinders

Aggregated studies of graphene nanoparticles is important for the effective utilization of their striking thermophysical properties and extensive industrial applications. This investigation is one such computational study to explore the flow of graphene oxide nanofluids with temperature dependant viscosity between two concentric cylinders. Buongiorno model is used to develop the flow of graphene nanofluids including the impacts of Soret and Dufour effects and the effects of nanoparticle characteristics such as thermophoresis and Brownian motion. The modelled equations are transformed and are numerically solved using linearization method together with Chebyshev’s spectral collocation method under convective conditions. The impacts of embedded parameters on temperature, concentration and skin friction profiles of the chosen nanofluid and their consequent impacts on the predominant cause for the generated entropy are studied. From the tabulated values of Nusselt number and Sherwood number, it is observed that convective heat transfer can be enhanced by thermal Biot number whereas Soret number enhances diffusive mass transfer and variable viscosity parameter preferably reduces the skin friction. A comparison table is presented and it shows that the values obtained from the present method are in good agreement with existing literature. Also, the obtained results are depicted and interpreted in detail. Furthermore, entropy generation is analysed and its irreversibilty is calculated.

Maximizing heat transfer potential with graphene nanofluids along with structured copper surfaces for pool boiling

Increasing the demand and depletion of energy sources confront every technological development with energy conversation and its utilization. Boiling heat transfer is the most applicable heat transfer method in many industries, from electronic chip manufacturing to heavy nuclear power plants. Hence, the augmentation of it is of prime importance for future requirements. The present investigation focused on the augmentation of boiling heat transfer by considering a novel V-pattern staggered copper surface for pool boiling in graphene nanofluid media. The study encompasses a detailed exploration of nanofluid concentrations ranging from 0.1% to 0.40 vol% prepared in equal volumes of dimethylformamide and distilled water. The nanofluid's stability is observed to be quite promising, and the results are presented. The wall superheat was drastically reduced to 48.73%, and the maximum heat transfer coefficient enhancement of 83.47% was achieved for 0.04% concentration of graphene nanofluid with a V-pattern surface compared to a smooth copper surface with water. This is due to the micro-level structured convection patterns promoted by the microstructures. The thermophysical properties of nanofluid and peculiar microstructures enhanced the relative heat transfer coefficient by 63.37%. On the other hand, two popular machine learning models, Random Forest Regression (RFR) and Multi-Layer Perceptron (MLP), are used to predict the boiling heat transfer coefficient. Moreover, it is observed that the RFR model fitted the data well and yielded the lowest mean absolute percentage error within the bounds of computational time.

Design and optimization analysis of a new double-layer tube type heat exchanger for lead-bismuth reactors

Double-layer heat tubes have been designed to effectively reduce the occurrence of heat pipe rupture accidents. However, inter-tube thermal contact resistance can decrease heat transfer efficiency, thus hampering the heat dissipation in the primary loop system of lead-bismuth reactors. Therefore, optimizing the design of double-layer heat tubes is necessary. This work focuses on the double-layer heat exchanger of a lead-bismuth reactor and utilizes gallium-based graphene nanofluids as a thermal interface material to fill the gap between the heat tubes. Furthermore, the impact of the length, wall thickness, outer diameter, and spacing of heat tubes on the heat transfer performance of the double-layer heat exchanger with and without the nanofluids has been analyzed. The study aims to optimize the JF factor and cost-effectiveness ratio (CER). Genetic algorithms are employed to optimize and evaluate the heat transfer performance of the main heat exchanger based on the four aforementioned parameters. Consequently, a new design scheme is obtained for the double-layer heat exchanger, which increases the optimized overall heat transfer coefficient of the main heat exchanger by 5.79%, pressure drop in the primary loop by 2.32%, JF factor by 5%, and CER by 24.62%. These results demonstrate that the gallium-based graphene nanofluids can effectively enhance the heat transfer performance of the double-layer heat exchanger while reducing the likelihood of steam generator tube rupture accidents.

Performance optimization of nanofluid-cooled photovoltaic-thermoelectric systems: A study on geometry configuration, steady-state and annual transient effects

In this study, we explored Photovoltaic-Thermoelectric (PV-TE) systems in-depth, addressing complexities in both steady-state and annual transient performance under realistic conditions. The analysis involved twelve distinct PV-TE configurations featuring diverse thermoelectric designs incorporating various semiconductors, multi-staging, non-uniform cross-sections, and material segmentation. Model 6, the PV-TE system with a multi-stage segmented rectangular design, emerged as the top performer, exhibiting a remarkable 12% increase in electric power output during peak sunlight compared to the base model, despite a marginal decrease in efficiency. Furthermore, this research delved into the potential of advanced nanofluid cooling, investigating options such as distilled water, titanium oxide, aluminum oxide, iron oxide, and graphene. The results underscores graphene nanofluid's superiority, demonstrating a significant enhancement in thermal management at an optimal flow velocity of 2 m/s. This improvement in thermal management refers to the effective heat dissipation and temperature control within the PV-TE system. This study underlines the critical role of strategic system design and component selection in optimizing the performance of PV-TE systems. By providing a comprehensive foundation for future developments in effective and sustainable energy solutions, this research contributes to advancing the understanding and implementation of PV-TE technology.

Effects of Surfactants on the Corrosion Behavior of Aluminum Alloy in Graphene Nanofluid

In this study, the corrosion behavior of aluminum alloy was investigated in graphene nanoplatelet (GNP) nanofluids prepared with different surfactants. The surfactants include sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), Tween 80, and Gum Arabic (GA). The corrosion properties of the alloy in the different GNP nanofluids were evaluated using potentiodynamic polarization tests at room temperature. The surface morphology of the aluminum alloy was analyzed using a scanning electron microscope coupled with an electron dispersive spectroscopy detector. The experimental results revealed that the addition of surfactants improves the resistance of the aluminum alloy to corrosion in the nanofluid. This was attributed to the adsorption of surfactants on the surface of the alloy to form a protective film layer, which reduces moisture permeability and enhances corrosion inhibition. The addition of GA was found to exhibit the highest inhibition efficiency. This was followed by Tween 80, SDS, and SDBS, which contributes the least inhibition. XRD post-corrosion analysis also reveals the presence of aluminum oxide and aluminum hydroxide phases on the surface of electrodes immersed in all the different GNP nanofluids.

Thermal and hydraulic performance of Al alloy-based 3D printed triangular microchannel heatsink governed by rough walls with graphene and alumina nanofluids as working liquid

Microchannel heat sinks (MCHS) are known for providing enhanced cooling performance but their fabrication requires complex and multi-step processes. The recent development of additive manufacturing has enabled the fabrication of state-of-art monolithic structures that had been impossible to build using conventional methods. In this work, a monolithic cross-flow triangular cross-section MCHS was fabricated from aluminum alloy (AlSi10Mg) using the Direct Metal Laser Sintering (DMLS) process. The microchannel wall surface roughness was measured and the cross-section shrinkage of the microchannels was compared with the initial design hydraulic diameter of 500 µm–1000 µm. The MCHS with an initial design hydraulic diameter of 750 µm possessed a relative wall surface roughness, R a of 7.7%. The triangular cross-section hydraulic diameter underwent a shrinkage of 15.2% and 5.3% in terms of the reduction in angle between adjacent side alloys. Experiments were conducted for Reynolds numbers between 50 and 275 with nanofluids containing graphene and Al2O3 nanoparticles in water/water +10% ethylene glycol; these were compared with their respective base fluids. The Poiseuille number indicated that flow was laminar developed with base fluid and laminar developing with nanofluid as coolant. Despite providing the lowest thermal resistance, the graphene nanoparticles in water created the greatest pressure drop leading to a reduced performance coefficient. Al2O3 nanoparticles in water/water +10% ethylene glycol were found to have 7.7% and 20% better performance coefficients than their respective base fluids.

Thermodynamic Modeling and Performance Evaluation of Absorption Refrigeration System with Graphene Nanofluid

The study presents a comprehensive computational analysis of an absorption refrigeration system that employs graphene nanofluids as the secondary fluid. The system's tube-type evaporator, utilizing copper tubes, was optimized and analyzed under varying nanofluid concentrations through thermodynamic modeling. Key thermal and design parameters were thoroughly examined, including evaporation area, heat flux, conductive and convective coefficients, and overall heat transfer coefficient. The findings demonstrate notable enhancements in the analyzed parameters when employing nanofluids in the system, with improvements of 5.2% in the pumping power of the secondary system and 0.8% in the evaporation area. These outcomes highlight the potential benefits of incorporating graphene nanofluids in absorption refrigeration systems, paving the way for more efficient and sustainable cooling solutions.