Development of water-ethylene glycol based graphene nanoplatelets/cellulose nanocrystal hybrid nanofluid as radiator coolants and its performance evaluation

Traditional thermal fluids are incapable of absorbing the significant amount of heat generated by high performance engines. Greater engine performance requires extra consumed fuel, exposing combustion chambers to excessive heat. An automotive cooling system is designed to maintain the engine temperature at optimal levels. With the rapid growth of technology in the automotive industry, there is a need to increase the performance of conventional cooling systems to improve engine performance. Radiator plays a prominent role in increasing the performance of the cooling system. However, there is a demand for higher thermal properties fluid as the transport medium because of the insufficient thermal performance of traditional fluids. Hybrid nanofluids are exceptional heat transfer liquids due to their superior thermal conductivity. An experimental approach to prepare, characterize and stabilize the hybrid nanoparticles (Graphene nanoplatelets and Cellulose nanocrystals-50:50) in the base fluid (Ethylene Glycol-Water-60:40)) and to analyze the thermo-physical properties of the newly developed hybrid nanofluids and this is used as a coolant in automobile radiators. Combining with the coupling effect of two nanomaterials, the prepared hybrid nanofluids confirmed the proper dispersion stability by Zeta potential and UV absorption analysis and also enhanced the thermal conductivity with the increase in the volume concentration from 0.01%-0.2%. The maximum enhancement for thermal conductivity was around 27% attained at 0.2% hybrid nanofluid. With the increase in the particle loading, the viscosity increased but declined with the temperature by 21%. Moreover, the specific heat is decreased with the increment of hybrid nanofluid concentration. The results from the statistical analysis showed 0.2% GNP/CNC hybrid nanofluid as the optimum concentration for radiator application. The experimental results at different flow rates for hybrid nanofluid (0.2% volume concentration) presented a 41.44% improvement for convective heat transfer coefficient as a result of improved thermal conductivity and surface area and 12.34% pressure drop with respect to base fluid, with an increased density and viscosity the Reynolds number increased with the flow rate and obtained value is 3863.55. With the particle loading, the physical characteristics influenced Nusselt number enhancement with 26.77% for the proposed hybrid nanofluid at 7.2 LPM. Further, the size reduction analysis from computational modeling recommended the reduced dimensions for the flat radiator tube (major diameter-0.016m and length-0.24m) for increased heat transfer coefficient at decreased volume concentration (0.01% GNP/CNC). These outcomes show the overall thermal improvement of the radiator cooling system, which can reduce the dimensions (size and weight) of the radiator by the application of a novel hybrid nanofluid. Novel hybrid graphene nanoplatelets/ cellulose nanocrystal-based hybrid nanofluids performed better in automobile applications and are recommended for heat transfer enhancement in automotive industry

Enhancement of the heat transfer in radiator with louvered fin by using graphene-based hybrid nanofluids

Newly developed hybrid nanofluids can enhance heat transfer performance of various automotive appliances. Improved thermophysical properties of this hybrid nanoparticles when used as coolants will enhance the effectiveness of the car radiators with improved engine cooling system. The present study involves the simulation-based analysis of thermal enhancement of Graphene based Hybrid Nanofluids in a Car radiator. System analysis is performed considering single tube component in the radiator for pattern development. CFD analysis is conducted using ANSYS FLUENT module. Graphene/Crystal Nanocellulose hybrid (Graphene + CNC) nanoparticles are suspended in water & ethylene glycol base fluids (40:60) at 0.01%,0.05%,0.1% &0.2 % volume concentration considering at 3-7 LPM inlet mass flow rate. The effect of various volume concentration, inlet temperature and flow rate on Pressure, Enthalpy, Entropy, Heat transfer coefficient, and Heat transfer rate has been examined by simulation. The results indicate that when using a Louvered fin in a radiator, Maximum enhancement of 60% in heat transfer rate, 53% increase of heat transfer coefficient, 65% increase in pressure are achieved for Graphene with CNC hybrid nanofluids when compared with Graphene based nanofluids. Using this type of hybrid coolants along with louvered fin in radiator can significantly improve the heat transfer performance of radiators

Assessment of thermophysical properties of hybrid nanoparticles [Graphene Nanoplatelets (GNPs) and Cellulose Nanocrystal (CNC)] in a base fluid for heat transfer applications

This article comprehensively investigates single (GNP) and hybrid nanofluids (GNPs/CNC nanoparticles), including nanofluid preparation and thermophysical properties. Nanoparticles were characterized using field emission scanning electron microscope, transmission electron microscope and X-ray diffraction analysis. A two-step approach is used in nanofluid preparation, and various analytical practices determine the prepared nanofluids. The range of the temperature set to measure the thermal conductivity of nanofluids is 20 °C to 50 °C using the ASTM D2717–95 norm. The present study range of the nanofluid volume concentration is from 0.01 vol% to 0.2 vol%. For the single GNP nanofluid, temperatures at room level indicated the thermal conductivity value in the range of 0.366 W•m−1•K−1 to 0.441 W•m−1•K−1; for hybrid nanofluid, the thermal conductivity values are 0.501 W•m−1•K−1 to 0.551 W•m−1•K−1. In addition, nanofluid's viscosity, density and specific heat capacity are the experimental density value increased with the concentration of nanoparticles with 1050 kg/m3 and 1060 kg/m3 for 0.01 % concentration of single/hybrid nanofluids, respectively. Finally, based on the findings, it can be determined that the thermal properties of the selected nanoparticles are beneficial, and hybrid nanofluid is an acceptable alternative to conventional/water-based fluids in terms of thermal properties in operational systems

An Approach for the optimization of thermal conductivity and viscosity of hybrid (Graphene Nanoplatelets, GNPs : Cellulose Nanocrystal, CNC) nanofluids using Response Surface Methodology (RSM)

Response surface methodology (RSM) is used in this study to optimize the thermal characteristics of single graphene nanoplatelets and hybrid nanofluids utilizing the miscellaneous design model. The nanofluids comprise graphene nanoplatelets and graphene nanoplatelets/cellulose nanocrystal nanoparticles in the base fluid of ethylene glycol and water (60:40). Using response surface methodology (RSM) based on central composite design (CCD) and mini tab 20 standard statistical software, the impact of temperature, volume concentration, and type of nanofluid is used to construct an empirical mathematical formula. Analysis of variance (ANOVA) is applied to determine that the developed empirical mathematical analysis is relevant. For the purpose of developing the equations, 32 experiments are conducted for second-order polynomial to the specified outputs such as thermal conductivity and viscosity. Predicted estimates and the experimental data are found to be in reasonable arrangement. In additional words, the models could expect more than 85% of thermal conductivity and viscosity fluctuations of the nanofluid, indicating that the model is accurate. Optimal thermal conductivity and viscosity values are 0.4962 W/m-K and 2.6191 cP, respectively, from the results of the optimization plot. The critical parameters are 50 °C, 0.0254%, and the category factorial is GNP/CNC, and the relevant parameters are volume concentration, temperature, and kind of nanofluid. From the results plot, the composite is 0.8371. The validation results of the model during testing indicate the capability of predicting the optimal experimental conditions

Heat transfer enhancement by hybrid nano additives—Graphene nanoplatelets/cellulose nanocrystal for the automobile cooling system (Radiator)

A radiator is used to remove a portion of the heat generated by a vehicle engine. It is challenging to efficiently maintain the heat transfer in an automotive cooling system even though both internal and external systems need enough time to keep pace with catching up with evolving engine technology advancements. The effectiveness of a unique hybrid’s heat transfer nanofluid was investigated in this study. The hybrid nanofluid was mainly composed of graphene nanoplatelets (GnP), and cellulose nanocrystals (CNC) nanoparticles suspended in a 40:60 ratio of distilled water and ethylene glycol. A counterflow radiator equipped with a test rig setup was used to evaluate the hybrid nano fluid’s thermal performance. According to the findings, the proposed GNP/CNC hybrid nanofluid performs better in relation to improving the efficiency of heat transfer of a vehicle radiator. The suggested hybrid nanofluid enhanced convective heat transfer coefficient by 51.91%, overall heat transfer coefficient by 46.72%, and pressure drop by 34.06% with respect to distilled water base fluid. Additionally, the radiator could reach a better CHTC with 0.01% hybrid nanofluid in the optimized radiator tube by the size reduction assessment using computational fluid analysis. In addition to downsizing the radiator tube and increasing cooling capacity over typical coolants, the radiator takes up less space and helps to lower the weight of a vehicle engine. As a result, the suggested unique hybrid graphene nanoplatelets/cellulose nanocrystal-based nanofluids perform better in heat transfer enhancement in automobiles

Ultrasonication an intensifying tool for preparation of stable nanofluids and study the time influence on distinct properties of graphene nanofluids – a systematic overview

Optimum ultrasonication time will lead to the better performance for heat transfer in addition to preparation methods and thermal properties of the nanofluids. Nano particles are dispersed in base fluids like water (water-based fluids), glycols (glycol base fluids) &oils at different mass or volume fraction by using different preparation techniques. Significant preparation technique can enhance the stability, effects various parameters & thermo-physical properties of fluids. Agglomeration of the dispersed nano particles will lead to declined thermal performance, thermal conductivity, and viscosity. For better dispersion and breaking down the clusters, Ultrasonication method is the highly influential approach. Sonication hour is unique for different nano fluids depending on their response to several considerations. In this review, systematic investigations showing effect on various physical and thermal properties based on ultrasonication/ sonication time are illustrated. In this analysis it is found that increased power or time of ideal sonication increases the dispersion, leading to higher stable fluids, decreased particle size, higher thermal conductivity, and lower viscosity values. Employing the ultrasonic probe is substantially more effective than ultrasonic bath devices. Low ultrasonication power and time provides best outcome. Various sonication time periods by various research are summarized with respect to the different thermophysical properties. This is first review explaining sonication period influence on thermophysical properties of graphene nanofluids

High heat transfer using hybrid engine coolant

To develop a stable nanofluid based on water & ethylene glycol by using nanoparticles graphene and crystal nano cellulose (cnc) and analyze the characteristic properties and the thermo-physical properties of water & ethylene glycol-based graphene/cnc hybrid nanofluids and evaluate the heat transfer performance of the newly developed hybrid nanofluid in a radiato

A systematic review on graphene-based nanofluids application in renewable energy systems: Preparation, characterization, and thermophysical properties

Graphene has attracted much attention from various researchers because of its enhanced mechanical, thermal, and physio-chemical properties. Graphene exhibits high thermal conductivity and stability, less erosion and corrosion than other available nanoparticles. Various existing literature signifies a large portion of the research focuses on stability, heat transfer characteristics and thermal conductivity of Graphene nanofluids. This review article represents a detailed analysis of the preparation techniques, characterization methods stability evaluation, and thermal properties enhancements of Graphene nanofluids. Comparative analysis of the effects of nanoparticle size, volume concentration and temperature on thermal conductivity and viscosity of Graphene nanofluids are reviewed based on heat transfer application. Graphene nanoparticles significantly enhances the thermal conductivity, viscosity, and heat transfer capacity of base fluid. It is noticed that the thermal conductivity of Graphene nanofluids increases with an increase in temperature and volume concentration. Applications of Graphene based nano coolant in automotive radiator, electronic cooling, solar cells and fuel cells are presented. This article can be the rapid reference model with investigational and theoretical analysis for highly critical considerations that impact the thermal performance of graphene based nanofluids in different heat transfer trends. This review also outlined the imminent challenges and future scope of research in Graphene