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An experimental investigation is conducted to study the thermal conductivity of ferrofluid in the dynamic condition. Effect of magnetic field strength on thermal conductivity of Fe3O4/water ferrofluid flowing in a tube with constant heat flux at different Reynolds numbers (400–800) and volume fractions (1–2 Vol.%) is examined. A set of thermocouples arranged in the radial direction is used to obtain the ferrofluid temperature profile and consequently the thermal conductivity. The data show that the thermal conductivity increases with the nanofluid concentration. Moreover, in the absence of magnetic field, an enhancement in thermal conductivity is observed with increasing Reynolds number while an opposite trend is observed under magnetic field. Compared to the water thermal conductivity, the maximum thermal conductivity enhancement of 32.3% was obtained for the ferrofluid with concentration of 2 Vol.% at Reynolds number of 400 and under magnetic field of 800 G. Our insights into the thermal conductivity of the ferrofluid under dynamic condition provide a new data and can be used to promote the accuracy of heat transfer calculations. [ABSTRACT FROM AUTHOR]

Abstract Lignin is currently an under-used material of the pulping and cellulosic ethanol production plants. The first and foremost objective in dealing with lignin is to augment the use of this aromatic compound and financial profitability of lignin-based processes. Of particular interests are lignin oxidation and depolymerization methods that harvest either the aromatic subunits of polymers or monomeric/oligomeric aromatic products used as platform chemicals. In this context, many studies have focused on the catalytic processes in which a nitroxyl catalyst, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), was employed to oxidize hydroxyl groups in lignin structure and selectively depolymerize lignin via cleavage of the ether and C C bonds. In discussing the advanced studies especially over the last decade on the oxidation of lignin models with TEMPO catalyst systems, this review provides a description of promising methods that can be employed for authentic lignin conversion. In the present review, a particular emphasis is dedicated to the proposed mechanisms for the oxidation of lignin and lignin models. [ABSTRACT FROM AUTHOR]

Nanocrystalline cellulose (NCC) a nature-based material, has gained significant attentions for its unique properties. The present study aims to investigate the flow behavior of cellulosic suspension containing non-wood pulp fibers and NCC, by means of rheological and pressure drop measurements. The NCC sample was prepared by sulfuric acid hydrolysis from Acacia mangium fibers. The rheological properties of kenaf/NCC suspensions were studied using viscosity and yield stress measurements. The pressure drop properties of the suspension flow were studied with respect to variation in flow velocity (0.4 m/s–3.6 m/s) and the NCC concentration (70 mg/l and 150 mg/l). The pressure drop results showed that the pulp suspension containing 150 mg/l NCC had higher drag reduction than kenaf suspension alone. The present insights into the flow of pulp/NCC suspension provide a new data and promote the application of NCC in industries. [ABSTRACT FROM AUTHOR]

The study of pulp suspension flow is one of the most significant scientific interests since the considerable changes in the flow behavior of water were noticed after adding a small amount of fiber to water. The rheological studies on Kenaf pulp (a fiber crop) suspensions revealed that concentration has a great influence on variations of viscosity and yielded stress values. Heat transfer and pressure loss data were obtained from Kenaf suspension flow at different concentrations over a wide velocity range in a straight pipe. Kenaf suspension at the concentration of 0.6 wt.% showed maximum drag reduction. A considerable increase in the heat transfer coefficient of Kenaf suspension (0.2 wt.%) was also observed. Such an increment in the heat transfer coefficient ratio of Kenaf suspension flow is interesting since the enhancement of heat transfer has mostly been reported for suspensions containing nanoparticles and not for natural fibers in microscale. Moreover, the effects of fiber length and flexibility on momentum and heat transfer data were studied. [ABSTRACT FROM AUTHOR]

In the present study a new synthesis method has been introduced for the decoration of platinum (Pt) on the functionalized graphene nanoplatelet (GNP) and also highlighted the preparation method of nanofluids. GNP–Pt uniform nanocomposite was produced from a simple chemical reaction procedure, which included acid treatment for functionalization of GNP. The surface characterization was performed by various techniques such as XRD, FESEM and TEM. The effective thermal conductivity, density, viscosity, specific heat capacity and stability of functionalized GNP–Pt water based nanofluids were investigated in different instruments. The GNP–Pt hybrid nanofluids were prepared by dispersing the nanocomposite in base fluid without adding any surfactant. The examined nanofluids were stable and no significant sedimentation was observed for a long time (22 days). Thermal conductivity of GNP–Pt nanocomposite dispersed in distilled water nanofluids shows an enhancement of 17.77% at 40 °C and 0.1% weight concentration. [ABSTRACT FROM AUTHOR]

In the present study, a facile method is used for preparation of functionalized graphene nanoplatelets (f-GNP) nanofluids. The effective thermal conductivity, density, viscosity, specific heat capacity, overall heat transfer coefficient and friction factor for fully developed turbulent flow of f-GNP/water nanofluids flowing through a square pipe at a constant heat flux were studied. f-GNP uniform nanocomposite was produced from a simple acid treatment reaction procedure. The surface characterization was performed by various techniques such as XRD, FESEM, FTIR and Raman. The f-GNP nanofluids were prepared by dispersing the functionalized nanoparticles in base fluid (water) without the assistance of a surfactant. As made nanofluids were stable for a long time and no sedimentation was observed. The experimental data for f-GNP nanofluids have shown significant enhancement in thermal conductivity and overall heat transfer coefficient in comparison to the corresponding water data. The percentage of enhancement is a function of weight concentration of nanoparticles and temperature. Highest improvement of overall heat transfer coefficient is 19.68% with 9.22% raise in friction factor for the weight concentration of 0.1% at a Reynolds number of 17,500 compared to those data from the base fluid. [ABSTRACT FROM AUTHOR]

In the present study a mixture of empty fruit bunch (EFB) fiber as a matrix material and graphene oxide (GO) as a guest was activated by processing with KOH. The structural characterization was performed by various techniques such as field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman. The as-synthesized hybrid containing activate carbon/graphene (ACG) was dispersed in ethylene glycol (EG) at various mass fractions in order to evaluate the thermo-physical and electrical properties such as thermal conductivity, electrical conductivity, viscosity, density and specific heat capacity of the suspensions at different temperatures. Thermal conductivity of ACG dispersed in EG based nanofluid shows an enhancement of 6.47% at 40 °C and weight fraction of 0.06%. [ABSTRACT FROM AUTHOR]

We have synthesized a nitrogen doped activated hybrid material containing carbon derived from empty fruit bunch (EFB) pulp as a waste material, and graphene oxide (GO) by using KOH and urea via one step thermal treatment at 800 °C. The results show an excellent attachment of GO to the carbon matrix with a spongy-like structure of final product (NACG), possessing the high surface area (2261.2 m 2 /g) and high nitrogen content (11.53%). A significant enhancement in thermal conductivity (10.16%) as well as in electrical conductivity (11433%) of dispersed NACG in the ethylene glycol (EG) confirms its potential application towards nanofluids. [ABSTRACT FROM AUTHOR]

In the present experimental work, a new synthesis method is introduced for decoration of silver on the functionalized graphene nanoplatelets (GNP–Ag) and preparation of nanofluids is reported. The thermo-physical properties, heat transfer performance and friction factor for fully developed turbulent flow of GNP–Ag/water nanofluids flowing through a circular tube at a constant heat flux were investigated. GNP–Ag uniform nanocomposite was produced from a simple chemical reaction procedure, which includes acid treatment for functionalization of GNP. The surface characterization was performed by various techniques such as XRD, FESEM, TEM and Raman. The GNP–Ag nanofluids were prepared by dispersing the nanocomposite in distilled water without the assistance of a surfactant and/or ultrasonication. The prepared nanofluids were found to be stable and no sedimentation was observed for a long time. The experimental data for GNP–Ag nanofluids were shown improvements of effective thermal conductivity and heat transfer efficiency in comparison with the corresponding to the base-fluid. The amount of enhancement was a function of temperature and weight concentration of nanoparticles. Maximum enhancement of Nusselt number was 32.7% with a penalty of 1.08 times increase in the friction factor for the weight concentration of 0.1% at a Reynolds number of 17,500 compared to distilled water. Improved empirical correlations were proposed based on the experimental data for evaluation of Nusselt number and friction factor. [ABSTRACT FROM AUTHOR]

The requirement for high quality pulps which are widely used in paper industries has increased the demand for pulp refining (beating) process. Pulp refining is a promising approach to improve the pulp quality by changing the fiber characteristics. The diversity of research on the effect of refining on fiber properties which is due to the different pulp sources, pulp consistency and refining equipment has interested us to provide a review on the studies over the last decade. In this article, the influence of pulp refining on structural properties i.e., fibrillations, fine formation, fiber length, fiber curl, crystallinity and distribution of surface chemical compositions is reviewed. The effect of pulp refining on electrokinetic properties of fiber e.g., surface and total charges of pulps is discussed. In addition, an overview of different refining theories, refiners as well as some tests for assessing the pulp refining is presented. [ABSTRACT FROM AUTHOR]

• GO nanosheets were fully exfoliated and decorated with CoFe 2 O 4 nanoparticles. • Gallic acid as a green agent was used to prepare the highly stable ferrofluids. • CoFe 2 O 4 /rGO nanohybrid is a promising material for the coolant applications. • Enhancement in thermal conductivity with rising temperature and concentration. • The Nusselt number enhancements of 27.8 % were obtained for 0.9 wt% at Re = 1713. The application of spinel ferrite decorated graphene hybrids in heat transfer has been limited mostly due to their poor stability in water. This study reports a straightforward strategy to synthesis a cobalt ferrite/reduced graphene oxide (CoFe 2 O 4 /rGO) nanocomposite with high water dispersibility characteristics through the treatment of synthesized hybrid material with Gallic acid (GA) as a green agent at room temperature. A π-π interaction between graphene and the aromatic ring of GA results in a suspension with high stability. The structure of the nanocomposite was investigated in detail by FTIR, XRD, TGA, VSM, Raman spectroscopy, FESEM, and TEM. Also, UV–vis spectroscopy is used to examine the stability of the stability of the CoFe 2 O 4 /rGO in the base fluid. The highly stable aqueous nanofluids were subsequently prepared from the products. Thermo-physical analyses of nanofluids revealed that the thermal conductivity ratio of ferrofluid prepared by the obtained CoFe 2 O 4 /rGO with 0.9 wt.% load of nanoparticles at 60 °C is rose to 1.46. Besides, the convective heat transfer in laminar flow regime conditions which passes a circular tube under uniform heat flux was examined. The nanofluid with the highest load of nanoparticles (0.9 wt.%) shown the maximum enhancement in Nusselt number of 27.8 % at Reynolds number of 1713. [ABSTRACT FROM AUTHOR]

The chemistry of lignin polymerization was studied in the past. Insights into the rheological behavior of the lignin polymerization system would provide crucial information required for tailoring lignin polymers with desired properties. The in-situ rheological attributes of lignin polymerization with a cationic monomer, [2-(methacryloyloxy)ethyl] trimethylammonium chloride (METAC), were studied in detail in this work. The influences of process conditions, e.g., temperature, component concentrations, and shear rates, on the viscosity variations of the reaction systems during the polymerization were studied in detail. Temperature, METAC/lignin molar ratio, and shear rate increases led to the enhanced viscosity of the reaction medium and lignin polymer with a higher degree of polymerization. The extended reaction time enhanced the viscosity attributing to the larger molecular weight of the lignin polymer. Additionally, the size of particles in the reaction system dropped as reaction time was extended. The lignin polymer with a larger molecular weight and Rg behaved mainly as a viscose (tan δ > 1 or G″ > G′) material, while the lignin polymer generated with smaller molecular weight and shorter Rg demonstrated strong elastic characteristics with a tan (δ) lower than unity over the frequency range of 0.1−10 rad/s. [ABSTRACT FROM AUTHOR]

Since most starting materials for tissue engineering are in powder form, using powder-based additive manufacturing methods is attractive and practical. The principal point of employing additive manufacturing (AM) systems is to fabricate parts with arbitrary geometrical complexity with relatively minimal tooling cost and time. Selective laser sintering (SLS) and inkjet 3D printing (3DP) are two powerful and versatile AM techniques which are applicable to powder-based material systems. Hence, the latest state of knowledge available on the use of AM powder-based techniques in tissue engineering and their effect on mechanical and biological properties of fabricated tissues and scaffolds must be updated. Determining the effective setup of parameters, developing improved biocompatible/bioactive materials, and improving the mechanical/biological properties of laser sintered and 3D printed tissues are the three main concerns which have been investigated in this article. [ABSTRACT FROM AUTHOR]

The work here looked into heat transfer performance in addition to friction loss of graphene nanoplatelet (GNP) - Platinum (Pt) hybrid nanofluids. The experiments were performed with non-changing limit parameters of heat-flux. Nanofluid movement was turbulent at a weight percentage ranging between 0.02 and 0.1%, with the Reynold number from 5000 to 17,500. The experimental findings revealed that compared with the base liquid, all nanofluid samples had higher heat transfer abilities. Nusselt number elevation and the increment of the heat transfer coefficient were found to be dependent on Reynold number, and the weight concentration of the nanocomposite. The greatest value recorded for Nusselt number was 28.48%, accompanied by a 1.109-fold penalty. There was a rise in friction factor with regards to the highest load of nanocomposite (0.1 wt%), with the Reynolds number of 17,500. [ABSTRACT FROM AUTHOR]

In the present study, the dynamic viscosity of alumina-engine oil nanofluid in different solid volume fractions and temperatures was experimentally investigated. The nanofluid samples were prepared in the solid volume fractions of 0.25%, 0.5%, 0.75%, 1%, 1.5% and 2% under the temperature range of 5 to 65 °C. The measurements were carried out by CAP 2000 + Viscometer, supplied by Brookfield of the USA. Using the experimental data, new correlations for predicting the dynamic viscosity of alumina-engine oil at different temperatures were proposed. The experiment results at different shear rates showed that all nanofluid samples exhibit the Newtonian behavior. The results also revealed that the viscosity of the nanofluid increases with the solid volume fraction. Moreover, it has been found that with increasing temperature, the viscosity of nanofluids decreases, and it was more tangible at the lower temperatures. The comparison between experimental findings and theoretical models showed that these models failed to predict the correct values of the viscosity of the nanofluids at all solid volume fractions. The experimental data also indicated that the maximum viscosity enhancement of nanofluid was 132% compared with that of base fluid. [ABSTRACT FROM AUTHOR]

The entropy generation based on the second law of thermodynamics is investigated for turbulent forced convection flow of ZrO2-water nanofluid through a square pipe with constant wall heat flux. Effects of different particle concentrations, inlet conditions and particle sizes on entropy generation of ZrO2-water nanofluid are studied. Contributions from frictional and thermal entropy generations are investigated, and the optimal working condition is analyzed. The results show that the optimal volume concentration of nanoparticles to minimize the entropy generation increases when the Reynolds number decreases. It was also found that the thermal entropy generation increases with the increase of nanoparticle size whereas the frictional entropy generation decreases. Finally, the entropy generation of ZrO2-water was compared with that from other nanofluids (including Al2O3, SiO2 and CuO nanoparticles in water). The results showed that the SiO2 provided the highest entropy generation. [ABSTRACT FROM AUTHOR]

Dielectric electroactive actuators are novel and significant smart actuators. The crucial aspect of construction of these devices is the bias mechanism. The current literature presents three main types of biases used in the construction of the DEAP actuators. In these solutions, the bias is caused by the action of a spring, a force of a permanent magnet or an applied mass. The purpose of this article is to present a novel type of DEAP bias mechanism using soft pneumatic spring. In contrast to the solutions presented so far, the soft pneumatic spring has been equipped with a sensor that measures the variable pressure of its inner chamber. We performed the modeling process of a soft pneumatic spring with the finite element method to predict its mechanical behavior. Furthermore, a prototype of the soft spring was molded and used to construct a dielectric electroactive polymer actuator. The principle of operation has been confirmed by the experiments with measurement of static and dynamics characteristics. The presented device can be used to control systems with an additional pressure-sensing feedback. [ABSTRACT FROM AUTHOR]

In the present study, the capture efficiency (CE) of nanoparticles flowing in a stenosed vessel was modeled computationally. The effect of parameters including the degree of constriction, constriction length, transversal location of constriction, location of current-carrying wire, and two consecutive occlusions in a cylindrical vessel with localized occlusion under the influence of magnetic field was investigated. The simulation results unveiled the substantial effect of the occluded vessel on the CE. The CE was enhanced from 21% to 24.1% by increasing the longitudinal distance of current-carrying wire from 2.5D to 5.5D. Besides, an increase in the degree of constriction from 0 to 65% resulted in a reduction in CE from 23.9% to 21%, respectively. Moreover, it was found that the change in the transversal location of constriction, and the presence of the consecutive occlusion, have a significant effect on the capturing particles in the tumor's location. Unlabelled Image • Numerical simulation of nanoparticles capture efficiency flowing in a stenosed vessel. • The higher the constriction degree percentages, the lower the nanoparticles' CE. • Shorter constriction length results in an increase in nanoparticles' CE. • The nanoparticles' CE are influenced by the location of wire. [ABSTRACT FROM AUTHOR]

Here, we demonstrate an on-demand heat transfer enhancement of water-based gallic acid treated CoFe 2 O 4 /rGO ferrofluid using constant/alternating magnetic field. Various parameters including weight fraction of nanoparticles, pressure loss, and mass flowrate were quantified and the optimum frequency was obtained. At Re = 571 without magnetic field, the average Nusselt number at 0.6 wt% ferrofluid increased by 12.9% relative to the pure water, while using a constant and oscillating magnetic field, the corresponding augmentation was 19.7% and 31.1%, respectively. The main mechanisms for heat transfer enhancement under the magnetic field were chain-like structure distribution of nanoparticles, boundary layer thickness, thermal conductivity, and Brownian motion of magnetite nanoparticles. The results revealed that the on-demand control of the ferrofluid heat transfer characteristics could be achieved through the utilization of different types of magnetic fields (constant/alternating) and their configurations. Unlabelled Image • GO nanosheets were exfoliated and decorated homogeneously with CoFe 2 O 4 nanoparticles. • CoFe 2 O 4 /rGO nanohybrid is a promising multifunctional nanocomposite for cooling. • Influences of magnetic field intensity and frequency are investigated. • Convective heat transfer enhancement is more pronounced at high mass concentration. • Nanoparticle aggregation on tube surface leads to higher local thermal conductivity. [ABSTRACT FROM AUTHOR]

• Heat transfer to turbulent nanofluids separation flow was studied experimentally. • The experiments were conducted at ER of 2 and the Re ranges of 4000–16,000. • The correlations for the Local and average Nu are proposed with good accuracy. Convective heat transfer plays a significant role in numerous industrial cooling and heating applications. This method of heat transfer can be passively improved by reconfiguring flow passage, fluid thermophysical properties, or boundary conditions. The broader scope of nanotechnology introduced several studies of thermal engineering and heat transfer. Nano-fluids are one of such technology which can be thought of engineered colloidal fluids with nano-sized particles. In the present study, turbulent forced convection heat transfer to nanofluids in an axisymmetric abrupt expansion heat exchanger was investigated experimentally. During heat transfer investigation, the functionalized multiwalled carbon nanotubes (MWCNT-COOH), polycarboxylate functionalized graphene nanoplatelets (F-GNP), SiO 2 and ZnO water-based nanofluids were used. The convective heat transfer coefficient of fully developed turbulent flow of nanofluids flowing through an abrupt enlargement with the expansion ratio (ER) of 2 was experimentally determined at a constant wall heat flux of 12,128.56 W/m2. The experiments were conducted at the Re ranges of 4000–16,000. The observed Nusselt numbers were higher than in the case of fully developed pipe flow indicating the level of the turbulent transport is high even though the recirculating velocities were a few percentages of the bulk mean velocity. The effect of Reynolds number and nanofluid's volume concentration on heat transfer and friction losses were studied, where all the results reveal that with the increase of weight concentration and Reynolds number, the local Nusselt number enhanced at the increment of axial ratios in all the cases showing greater heat transfer rates than those of the base fluids. Comparison between the examined four types of nanofluids, show that the carbon-based nanofluids have a greater effect on enhancing heat transfer (33.7% and 16.7% heat transfer performance improvement for F-GNP and MWCNT nanofluids respectively at 0.1 wt% concentration) at the downstream of the sudden expansion pipe. There is no reported work dealing with the prediction of the local Nusselt number at the distance equivalent to the axial ratio and flow through sudden expansion. So far, two excellent correlations for the Local Nusselt number are proposed with reasonably good accuracy. Furthermore, a new correlation is developed for the average Nusselt number. [ABSTRACT FROM AUTHOR]

A numerical study is carried out to investigate the effects of different geometrical parameters and various nanofluids on the thermal performance of rib–grooved channels under uniform heat flux. The continuity, momentum and energy equations are solved by using the finite volume method (FVM). Three different rib–groove shapes are studied (rectangular, semi-circular and trapezoidal). Four different types of nanoparticles, Al 2 O 3 , CuO, SiO 2 and ZnO with different volume fractions in the range of 1% to 4% and different nanoparticle diameters in the range of 20 nm to 60 nm, are dispersed in the base fluids such as water, glycerin and ethylene glycol. The Reynolds number varies from 5000 to 25,000. To optimize the shape of rib–groove channels different rib–groove heights from 0.1 D h (4 mm) to 0.2 D h (8 mm) and rib–groove pitch from 5 e (20 mm) to 7 e (56 mm) are examined. Simulation results reveal that the semi-circular rib–groove with height of 0.2 D h (8 mm) and pitch equals to 6 e (48 mm) has the highest Nusselt number. The nanofluid containing SiO 2 has the highest Nusselt number compared with other types. The Nusselt number rises as volume fraction increases, and it declines as the nanoparticle diameter increases. The glycerin–SiO 2 nanofluid has the best heat transfer compared to other base fluids. It is also observed that in the case of using nanofluid by changing parameters such as nanoparticle diameter, volume fraction and base fluids the skin friction factor has no significant changes. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) were functionalized by hexylamine (HA) in a promising, cost-effective, rapid and microwave-assisted approach. In order to decrease defects and remove acid-treatment stage, functionalization of MWCNTs with HA was carried out in the presence of diazonium reaction. Surface functionality groups and morphology of chemically-functionalized MWCNTS were characterized by FTIR, Raman spectroscopy, thermogravimetric analysis (DTG), and transmission electron microscopy (TEM). To reach a promising dispersibility in oil media, MWCNTs were functionalized with HA. While the cylindrical structures of MWCNTs were remained reasonably intact, characterization results consistently confirmed the sidewall-functionalization of MWCNTs with HA functionalities. Then, HA-treated MWCNTs-based turbine oil nanofluids (HA-MWCNTs/TO) with different volume fractions were synthesized and employed to be investigated in terms of heat transfer potential. Convective heat transfer coefficient of HA-MWCNTs/TO as a positive parameter and pressure drop as a negative factor were investigated for various volume fractions. While results suggested a weak increase in the pressure drop by MWCNTs loading into the TO, lack of acidic agents, the performance index higher than 1 and a significant increase in the convective heat transfer open a new gateway for introducing this economical product for industrial applications in turbines and can be a capable alternative for conventional TO. [ABSTRACT FROM AUTHOR]

Nanofluids are fluid nanoparticle suspensions that exhibit enhanced properties at modest nanoparticle concentrations. Nanofluids have unique heat transfer properties and are utilized in high heat flux systems (e.g., electronic cooling systems, heat exchanger liquids, solar collectors, and nuclear reactors). However, suspension stability is critical in the development and application of these heat transfer fluids. Reynolds number, mass concentration, and particle size control the heat transfer behavior of fluids. Sedimentation and agglomeration of nanoparticles in nanofluids and their dispersion have rarely been investigated. Therefore, this paper explains the parameters that affect the stability of nanofluids and the different techniques used to evaluate the stability of nanofluids. This paper also presents an updated review of properties of nanofluids, such as physical (thermal conductivity) and rheological properties, with emphasis on their heat transfer enhancement characteristics. Studies on zeta potential as a function of pH are discussed and extended further to identify opportunities for future research. [ABSTRACT FROM AUTHOR]

The present research highlighted on the use of Reduced Graphene Oxide (RGO) and its hybrid complexes in an effort to improve the convective heat transfer performance in closed conduit configuration. The RGO was synthesized via the reduction process of chemically exfoliated Graphene Oxide (GO) using Tannic Acid (TA) as reductant. Different amount of pristine carbon sources (i.e. Multiwall Carbon Nanotube (MWCNT), Carbon Nanofiber (CNF) and Graphene nanoPlatelets (GnP)) was allowed to interact with RGO to form a hybrid complexes aiming to explore the capability of the mixtures to promote heat transfer process. It was discovered that the trend of results appeared to coincide to the previous documented findings on heat transfer enhancement related to the addition of graphene based materials. Further, the enhancement of heat transfer coefficient was beyond the increase in thermal conductivity alone which suggested prominent contribution from both the particle and turbulent induced flow characteristics. The enhancement was more pronounced at the entrance of the heating section as well as at high Reynolds number ( Re ), paving opportunities for further investigation to gain in-depth understanding on the mechanisms involved. As high as 144% enhancement in Nu was recorded near the conduit entrance and about 63% at the downstream section. Studies on hydrodynamic parameters indicated negligible increase in pressure loss as well as friction factor for RGO and its hybrid mixtures, indicating the potential use of RGO as favorable additives in addressing the persistent limitation of conventional heat transfer liquid within the perspective of convective heat transport system. [ABSTRACT FROM AUTHOR]

Biofuels are acting as a renewable replacement for petroleum fuels due to some environmental and economic benefits. They are prepared by blending a major portion of diesel fuel and a certain minor percentage of bio-oils, which provides less greenhouse gas (GHG) compared to pure diesel. Recently, bioethanol has been the most widely used biofuel for transportation. Bioethanol can be produced from different kinds of agricultural raw materials classified into three categories: simple sugars, starch, and lignocellulose. Use of bioethanol-blended gasoline fuel for automobiles can significantly reduce petroleum use and exhaust GHG emission. Bioethanol from sugar cane, produced under the proper conditions, is essentially a clean fuel and has several clear advantages over petroleum-derived gasoline in reducing GHG emissions and improving air quality in metropolitan areas. However, there remains a compromise between GHG emission and saving of fossil fuel energy by introducing bioethanol either totally or as a blending component of engine fuel. Thus, considering biofuel as a replenishable energy source, the future pathway of energy management could be planned. [ABSTRACT FROM AUTHOR]

Cellulose nanofibers (CNFs) and their applications have recently gained significant attention due to the attractive and unique combination of their properties including excellent mechanical properties, surface chemistry, biocompatibility, and most importantly, their abundance from sustainable and renewable resources. Although there are some commercial production plants, mostly in developed countries, the optimum CNF production is still restricted due to the expensive initial investment, high mechanical energy demand, and high relevant production cost. This paper discusses the development of the current trend and most applied methods to introduce energy-efficient approaches for the preparation of CNFs. The production of cost-effective CNFs represents a critical step for introducing bio-based materials to industrial markets and provides a platform for the development of novel high value applications. The key factor remains within the process and feedstock optimization of the production conditions to achieve high yields and quality with consistent production aimed at cost effective CNFs from different feedstock. [ABSTRACT FROM AUTHOR]