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This paper presents the study results of the morphology, physical properties, thermal stability, and mechanics of bioplastic blends made from tannia and cassava starch, with a varying weight from 0 to 95%. The addition of tannia to the cassava starch-based bioplastic composition has the ability to reduce the number of pores, density, and water absorption with an average thickness of 0.21-0.29 mm. It also increased moisture content due to its nature, which is more hydrophilic than cassava starch. The result showed that the tensile strength of bioplastic ranged from 0.81-1.33 MPa and elongated from 31-35%. In addition, the thermal analysis data showed that the glass transition temperature shifted marginally due to intermolecular activity. This shows that tannia starch has promising potential as an alternative raw material for bioplastics to replace cassava starch which is more dominantly used as a food source.

The investigation of the utilization of enriched 208Pb as a coolant to enhance the performance of a long-life fast reactor with a Modified CANDLE (Constant Axial shape of Neutron flux, nuclide densities, and power shape During Life of Energy production) burnup scheme has performed. The analyzes were performed on a reactor with thermal power of 800 MegaWatt Thermal (MWTh) with a refueling process every 15 years. Uranium Nitride (enriched 15N), 208Pb, and High-Cr martensitic steel HT-9 were employed as fuel, coolant, and cladding materials, respectively. One of the Pb-nat isotopes, 208Pb, has the smallest neutron capture cross-section (0.23 mb) among other liquid metal coolants. Furthermore, the neutron-producing cross-section (n, 2n) of 208Pb is larger than sodium (Na). On the other hand, the inelastic scattering energy threshold of 208Pb is the highest among Na, natPb, and Bi. The small inelastic scattering cross-section of 208Pb can harden the neutron energy spectrum. Therefore, 208Pb is a better neutron multiplier than any other liquid metal coolant. The excess neutrons cause more production than consumption of 239Pu. Hence, it can reduce the initial fuel loading of the reactor. The selective photoreaction process was developing to obtain enriched 208Pb. The neutronic was calculated using SRAC and JENDL 4.0 as a nuclear data library. We obtained that the modified CANDLE reactor with enriched 208Pb as coolant and reflector has the highest k-eff among all reactors. Meanwhile, the natPb cooled reactor has the lowest k-eff. Thus, the utilization of the enriched 208Pb as the coolant can reduce reactor initial fuel loading. Moreover, the enriched 208Pb-cooled reactor has the smallest power peaking factor among all reactors. Therefore, the enriched 208Pb can enhance the performance of a long-life Modified CANDLE fast reactor.

Pulsed electric field (PEF) pasteurisation keeps treated liquid food fresh and nutritious compared to traditional thermal pasteurisation. However, PEF adoption is still limited on an industrial scale due to a lack of practical systems. As a result, a great deal of research has gone into overcoming the limitations of the existing systems. Keeping this in mind, the current study contributes to the improvement of the electroporator. The heterogeneous electric field’s distribution raises the temperature of the treated food samples. Liquid laminar flow is a reason for heterogeneous electric field’s distribution in continuous treatment. Hotspots may also be created by using an inefficient high-voltage waveform in addition to the heterogeneous electric field distribution. This study rectifies the heterogeneous distribution by proposing an improved coaxial treatment chamber and double-exponential waveform to replace the exponential-decaying waveform. A static mixer provides an increased mixing, i.e. disrupting the laminar flow, inside the treatment zone. COMSOL based computational model was developed to study flow behaviour and corresponding temperature distribution in the proposed coaxial treatment chamber with sieves. Based on the model, it has been concluded that coaxial electrodes with sieves provide more homogeneous flow properties inside the treatment chamber. The effectiveness of the double-exponential (DE) waveform was validated using MATLAB. A three-stage Marx generator giving the DE waveform was designed and constructed. The performance of the improved treatment chamber together with the DE waveform, known as the electroporator, was studied using chemical and microbial analysis. Untreated, PEF treated, and thermal treated orange samples were stored at 4°C for 9 days before being examined. The lowest microbial growth was observed in both the PEF treated with sieves and thermally treated food samples than the untreated sample. However, treated juices’ visual and chemical colour analysis showed that the PEF-treated sample acquired a brighter appearance than a thermally processed sample. Thus, this study provides significant findings in developing and utilising an electroporator to inactivate microorganisms.

Today, due to the reduction of energy resources in the world and its pollutants, energy storage methods and increase the thermal efficiency of various systems are very important. In this research, the thermal efficiency and energy storage of two heat exchangers have been investigated in series using phase change materials (RT82) and single wall carbon nanotubes (SWCNT) and graphene quantum dot nanoparticles (GQD) In this research, two heat exchangers have been used in combination. The first heat exchanger was in charge of storing thermal energy and the second heat exchanger was in charge of heat exchange. The reason for this is to improve the heat exchange of the main exchanger (shell and tube) by using heat storage in the secondary exchanger, which has not been addressed in previous research. The results of this study showed that using two heat exchangers in series, the thermal efficiency of the system has increased. Also, the heat energy storage of the double tube heat exchanger was obtained using phase change materials in the single-walled carbon nanotube composition of about 3000 W. The average thermal efficiency of the two heat exchangers as the series has increased by 52%. In general, the effect of the two heat exchangers on each other was investigated in series with two approaches (energy storage and energy conversion) using fin and nanoparticles, which obtained convincing results.

Nanofluid had been widely used in heat transfer applications due to its better thermophysical properties. However, nanofluid had a problem in the stability of nanoparticles suspended in the based fluid. Several ways had been done to increase the stability of nanofluids including using surfactants. The purpose of this review is to uncover the stability and heat transfer performance of nanofluid using surfactants. A systematic review was used to collect the related articles for this review. This review shows the mechanism of two types of surfactants that had been used which are ionic and non-ionic. Furthermore, the stability of nanofluid is very important to enhance the thermal performance of nanofluid. The recommendations are highlighted to study the optimum amount of surfactant for respective nanofluids.

The last decade has seen the rapid advancement of nanofluid in several ways. Nanofluid based on the refrigerant have been introduced as nanorefrigerant in recent years due to their significant effects on the efficiency of heat transfer. Previous studies showed some limitation in ways of dispersing nanoparticles into refrigerant. Hence, a new idea of adding nanoparticles into refrigerant has been presented. A mixing chamber has been designed to mix nanoparticles into high pressure refrigerant. The mixing chamber design is drawn with five different wall thickness which are 2 mm, 4 mm, 6 mm, 8 mm and 10 mm to investigate the sturdiest design that can withstand high pressure. Static structural analysis is performed to all designs with different wall thickness on SolidWorks Simulation. The maximum values of von Misses stress and displacement has been presented in this paper. Validation of the results are made by comparing the maximum values of von Mises stress with yield strength of the material. Mixing chamber with wall thickness of 10 mm showed the best results.

Electronic devices are becoming more efficient while getting a smaller size and compact design thus increase heat generation significantly. High heat generation from high technology electronic devices are needed to be cool down or control its temperature to prevent overheating problems. Due to the high cooling performance of liquid cooling, the electronic cooling system is shifting from an air-cooling system to a liquid cooling system. In the past few decades, numerous methods proposed by researchers for the central process unit (CPU) cooling using the liquid system either active cooling or passive cooling system. Other than physical configuration such as heat sink design, different configurations of working fluids are widely been studied by most of the researchers. Different working fluids have different heat transfer performance. Furthermore, a recent study has come out more interesting finding using nanofluid which can enhance heat transfer performance of liquid cooling. Nanofluid is a working fluid that has nanoparticles disperse in the base fluid which can increase the thermal properties of the based fluid. In this paper, comprehensive literature on the type of working fluid used in the respective system and methods of liquid cooling system for CPU including its cooling performance. Furthermore, this review paper discussed the different configuration of the liquid block and also the working fluid that had been used in the CPU cooling system.

Nanofluid is a colloidal mixture consisting of nano-sized particles dispersed in a liquid medium. It improves heat transfer properties and promotes high energy efficiency in a wide spectrum of engineering applications. In recent years, particularly in the automotive industry, the addition of nanofluid in diesel/biodiesel as an additive for ICE has become an attractive approach to promote enhanced combustion efficiency and emission reduction due to their superior thermophysical properties. Many researchers have previously demonstrated that the addition of nanoparticles in diesel/biodiesel fuel improved the overall engine combustion characteristics. As a whole, this study aims to summarize the recent research findings related to the effect of nanoparticles on the fuel properties and engine combustion efficiency. Furthermore, different types of additive blended with varying fuel properties are also compared and discussed. Lastly, the advantages and prospects of using nanofluid as an additive fuel are summarized for future research opportunities.

Thermoacoustic refrigerators and heat pumps are considered one of the important emerging green technologies. They are based on the use of acoustic pressure waves to supply cooling or heating effects. The oscillating gas interaction with a solid wall called the stack generates thermoacoustic effects. This study presents the effects of the operating conditions and geometric parameters on the temperature difference across the stack and the coefficient of performance of a thermoacoustic heat pump at different cooling loads. The design steps of these systems were also demonstrated. Theoretical study of the operation conditions and geometric parameters was presented using “DeltaEC”. The results showed that higher harmonics are less desirable for thermoacoustic phenomena as they lower the temperature difference across the stack. Further insights into the effects of amplitude pressure, mean pressure and stack geometries were also demonstrated. This study helps to establish the concepts and design steps for thermoacoustic refrigerators and heat pumps.

In this research, the thermal attributes of shell and finned tube heat exchanger such as thermal efficiency, pressure drop, heat transfer rate and average temperature in the tube side of heat exchanger with using the different volume concentration of nanoparticles (SWCNT and Graphene quantum dot) at the various Reynolds number by applying either fin blades and without fin blades have been conducted numerically. In this heat exchanger the hot fluid or nanofluid flows in the tube section and cold fluid or pure water moves in the shell side. As regarding to results obtained the majority of thermal characteristics like heat transfer rate, pressure drop and effectiveness enhanced with augmentation of Reynolds number and increasing of volume concentration of nanofluids to 1% volumetric of working fluid whereas at the higher volume concentrations of nanoparticles (upper from 1% volumetric) the thermal properties of heat exchanger decreased generally. Also pressure drop intensifies with increment of Reynolds number and volume concentration of nanoparticles that at higher Reynolds number the effects of nanoparticles on the pressure drop were more noticeable. The average temperature of heat exchanger in the end section of inside tubes increased with augmentation of Reynolds number and nanoparticles. Finally, according to the results obtained in this study, most impression on the thermal attributes enhancement was found by employing of finned tubes compared to other factor which this factor increased heat transfer rate of heat exchanger by almost 188% also the effects of nanoparticles at the high levels of volume concentration especially for 5% of SWCNT nanoparticle on the pressure drop obtained about 80% compared to the base fluid.

In this research work, novel hybrid graphene-silver (Gr-Ag) nanomaterial has been used for first time with paraffin wax as a phase change material (PCM) to improve its thermo-physical properties. Thermal and electrical energy efficiencies of the novel synthesized nanocomposite (PCM/graphene-silver) has been investigated in solar thermal collector systems (CPV/T). This paper focuses on preparation, characterization, thermo-physical properties and energy efficiency in concentrated photovoltaic/thermal (CPV/T) system of new class of nanocomposites induced with hybrid Gr-Ag nanomaterial in three different concentrations. The specific heat capacity (cp) of hybrid PCM/graphene-silver nanocomposite increased by introducing hybrid Gr-Ag nanomaterial. Electrical and thermal energy performance of the hybrid PCM/graphene-silver is investigated in a CPV/T system using MATLAB 2017b program. The improvement of cp is found to be ~ 40% with 0.3 mass% of hybrid Gr-Ag nanomaterial loaded in PCM. The highest thermal conductivity increment is found to be ~ 11% at 0.3 mass% concentration of hybrid Gr-Ag nanomaterial in PCM. The endothermic enthalpy value of the hybrid PCM/graphene-silver nanocomposite is found to be ~ 75.6 J g−1 at 0.1 mass% loading concentration of hybrid Gr-Ag nanomaterial. Melting point of hybrid PCM/graphene-silver nanocomposite with loading concentration of 0.3 mass% is measured to be 73.2 °C. The highest thermal efficiency using the hybrid graphene-silver nanoparticles reached the value of 39.62% which represents 4.16% increment in comparison with the pure PCM. The equivalent electrical efficiency is improved by 2.8% at the loading concentration of 0.3 mass% of the hybrid Gr-Ag nanomaterial. These new class of nanocomposites represented the capability of enhancement in the performance of the CPV/T system consisting of lower PV temperatures, higher temperature gains across the cooling fluid and higher electrical and thermal efficiencies.

The electric-field-assisted hydrogenation and corresponding resistance modulation of NdNiO3 (NNO) thin-film resistors were systematically studied as a function of temperature and dc electric bias. Catalytic Pt electrodes serve as triple-phase boundaries for hydrogen incorporation into a perovskite lattice. A kinetic model describing the relationship between resistance modulation and proton diffusion was proposed by considering the effect of the electric field during hydrogenation. An electric field, in addition to thermal activation, is demonstrated to effectively control the proton distribution along its gradient with an efficiency of ∼22% at 2 × 105 V/m. The combination of an electric field and gas-phase annealing is shown to enable the elegant control of the diffusional doping of complex oxides.

The last decade has seen the rapid enhancement of nanofluid in several ways. Nanofluid with refrigerant base have been introduced as nanorefrigerant in recent years due to their significant effects on the efficiency of heat transfer. A brief review of past studies on nanorefrigerants and their performance in thermodynamics and heat transfer area are reported in this paper. Some current challenges and future prospect of nanorefrigerant will also be highlighted.

Rapid development in the electronic industry witnesses many tremendous advanced technologies which work with high power density. As a result, an advanced cooling technique, namely, microchannel heat sink (MCHS) is required to fulfil the current cooling demand due to unpredicted increment of power density in a high-density microchip. A microchannel heat sink performance can be enhanced by improving the working fluid properties and or improving the design of cooling passage that contributes to the augmentation of heat transfer rate. In this paper, the optimization of hydrothermal performance was conducted by studying the effect of triangular cavity pitch location (Cavity 1, CV1: 60 µm; Cavity 2, CV2: 100 µm; Cavity 3, CV3: 140 µm) on fluid flow and heat transfer characteristic in the hybrid microchannel heat sink (Triangular cavity with rectangular rib microchannel heat sink, TC-RR MCHS). The result revealed that the TC-RR MCHS with the triangular cavity pitch location of 140 µm (CV3) showed superior performance over other pitch locations (CV1 and CV2) for all the Reynolds number (Re number). The optimum Performance Factor, , achieved by CV3 pitch location was 1.76 at Re number of 350. It indicates that the proposed design with CV3 is suitable for the technology that requires less pumping power consumption

Common phase change materials (PCMs) possess very low thermal conductivity whilst hybrid PCM with graphene filler could be produced to achieve increased thermal conductivity. This research focuses on the effects of graphene flakes on the thermal conductivity of a PCM (paraffin wax). Three experimental parameters at different levels of average lateral sizes of graphene flakes (4.5, 5 and 7µm), mass fractions (0.1, 0.2 and 0.25 wt.%), and rising temperatures (25-75°C) are considered. For the first time in the literature, the impact of various parameters on the thermal conductivity performance of the nanoPCM-based graphene nano-composites is investigated extensively by adopting response surface methodology supported by central composite design. Thermal conductivity prediction is proposed by a new general correlation and a promising value of the coefficient of determination (R2) higher than 0.88. Amongst the investigated various variables in terms of impact on thermal conductivity, the temperature is identified as the most influential parameter on response variables. According to the implemented optimization technique, for the composite with the average graphene flake size of 4.5 µm, the optimum value of the thermal conductivity is found 0.275 W/m K at the mass fraction of 0.186 wt.% and temperature of 69.73°C.

This study was undertaken to investigate some specific problems that limit a safe design and construction of structures on problematic soils. An experimental study was carried out to examine the influence of loading rate and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural materials was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39%, 57% and 75%. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shearing rate was found to decrease the shear stress and internal friction angle for all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between organic soil and structural materials. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength.

In this study, the single point incremental forming (SPIF) method was applied to the half spherical-shaped vent cap products with 1mm thickness of aluminium. The dimensions of the blank before forming is 1x O225mm, and the final dimensions of the product are 69.50 x O225mm. Blank material is gripped to the fixture explicitly made according to the final product shape. The SPIF process uses a punch tool with a diameter of 12mm, so the process condition parameters that will be used are 0.5 mm step down, 35 rpm spindle speed, and 1000 mm/min feed. The lubrication used is VG 32 isocut cutting oil. The SPIF process for air cap products is carried out using two forming strategies, namely single-stage and multi-stage. In the single-stage formation strategy, the product experienced a tear at a depth of 18.5mm. Whereas in a multi-stage forming strategy, a product with three forming stages was successfully formed without tears, but experienced changes in dimensions and shape at the end of the final stage. Therefore the testing of SPIF process in a half-spherical shaped still requires development to get the planned shape and dimensions.

Increasing dispersion stability is the main issue in recent research at magnetorheological (MR) fluids. The presentation of nanoparticle addictive in MR fluids is an effective method not only to increase dispersion stability but also increasing performance in MR fluids. In this study, the effect of hard magnetic CoFe2O4 nanoparticles addition on rheological properties and dispersion stabilization had been studied. Rheological properties were investigated using a rheometer at room temperature. The result showed that the addition of CoFe2O4 nanoparticles 1wt% in particles of MR fluids were improving the shear stress and viscosity of MR fluids. Both MR fluids with and without nanoadditives behaving like a Newtonian fluid at the off-state condition and act like Bingham fluid at the on-state condition. Moreover, MR fluid with CoFe2O4 additives had a higher sedimentation ratio than MR fluids without additives.

Microchannel heat sink (MCHS) is an advanced cooling technique to fulfil the cooling demand for electronic devices installed with high-power integrated circuit packages (microchips). Various microchannel designs have been innovated to improve the heat transfer performance in an MCHS. Specifically, the utilisation of nanotechnology in the form of nanofluid in an MCHS attracted the attention of researchers because of considerable enhancement of thermal conductivity in nanofluid even at a low nanoparticle concentration. However, a high-pressure drop was the main limitation as it controls the MCHS performance resulted from heat transfer augmentation. Therefore, this study aimed to critically summarise the challenges and limitations of both single and hybrid passive methods of MCHS. Furthermore, the performance of nanofluid as a coolant in the MCHS as affected by the type and concentration of nanoparticle and the type of base fluid was reviewed systematically. The review indicated that the hybrid MCHS provides a better cooling performance than MCHS with the single passive method as the former results in a higher heat transfer rate with minimal pressure drop penalty. Besides that, further heat transfer performance can be enhanced by dispersing aluminium dioxide (Al2O3) nanoparticles with a concentration of less than 2.0% (v/v) in the water-based coolant.

Silica nanofiller or nanosilica is known to be one of the most widely used fillers in polymer nanocomposite. Nevertheless, agglomeration of nanosilica within polymer matrix has been discovered to be a limitation towards enhancing the insulating properties. With this regard, plasma discharge is found to have a great potential in overcoming the agglomeration of nanofiller despite using chemical solvents or coupling agents. The effectiveness of plasma treatment in functionalizing the nanofiller is influenced by few factors, including treatment duration. However, the optimum treatment duration is still yet to be explored to determine its effect on the morphology characteristic of nanofiller. Therefore, this study investigates the effect of plasma treatment duration on nanosilica by varying the treatment times to 1, 3, and 5 minutes. The glow mechanism of plasma discharge is produced by exhilarating the plasma reactor with 0.5 kV and 20 kHz of source parameters. The characteristics of plasma discharge are analyzed according to the discharge current and the properties of the Q-V Lissajous figure. In comparison, the morphology of nanosilica is characterized by using a Perkin Elmer FTIR spectrometer. The result showed that the plasma treatment duration is proportional to the intensity of the hydroxyl group functionalized on the nanosilica morphology with the highest intensity at 5 minutes of treatment time.

Dielectric breakdown of air bubbles embedded in liquid food is a limiting factor in the pulsed electric field (PEF) pasteurization. Therefore, a proper chamber's geometry, air degasification, and estimation of electric field enhancements (due to gas bubbles) are powerful strategies to overcome this limitation. In this study, a coaxial treatment geometry loaded by an orange liquid sample encompassing a gas bubble demonstrated importance in the electric field distributions. The development of a gas bubble induces the non-uniform electric field near the bubble surface. A numerical analysis through COMSOL Multiphysics was done to observe the effects of a bubble diameter and the liquid's flow inside the coaxial chamber geometry. An air bubble with a comparable diameter has influenced more to the electric potential difference, and the position of the air bubble also affects the value of perturbation in the electric potential. This study supports the development of an electroporator for PEF pasteurization of liquid food.

Cold plasma with glow discharge mechanism exhibiting a uniform ionization process when a background gas passes through the discharge region of the plasma reactor under a certain optimum configuration of input parameters. A glow discharge is a homogeneous and effective mechanism of cold plasma for industrial applications due to the continuous and stable discharge process compared to the filamentary discharge. Meanwhile, the development of glow discharge plasma operated under atmospheric pressure condition is indispensable to overcome the weaknesses of filamentary discharge plasma, such as the nonuniform and discontinuous discharge process. The discharge mechanism is essentially dependent upon the input parameters of the plasma system, such as the amplitude of the voltage supply, the operating frequency, and the flow rate of the background gas. In this paper, the effects of voltage supply on plasma discharge characteristics produced from the plasma jet reactor with the high-voltage electrode are discussed. The value of voltage supply is tuned to be suitable with the discharge gap, frequency supply, and background gas flow rate in producing the homogeneous glow plasma discharge. The characteristics of the glow plasma discharge produced are analyzed based on the pattern of the charge-voltage Lissajous figure and time-domain discharge current techniques. Results show that the most efficient and uniform plasma is disclosed by the configuration of input parameters such as 0.5 kV of supply voltage, 20 kHz of operating frequency, and 0.8 L/min of purified helium gas flow rate. The parallelogram-like Lissajous figure obtained indicating the homogeneous plasma discharge with a constant value of discharge capacitance.

The partial discharge and dielectric breakdown strength characteristics are among the parameters measured for insulation development, especially for the power cable. Cross-linked polyethylene (XLPE) is a type of host polymer used widely to insulate the conductor part of the medium and high voltage cables. The resilience of the cable commonly depends on the performance of the polymer to insulate the conduction part efficiently. However, the dielectric performances of the XLPE degraded due to various aging factors. Adding the nanofillers into the XLPE matrix might enhance the dielectrics properties of the XLPE. In this study, silica (SiO2) nanofillers have been added into the XLPE matrix with various loadings to improve the partial discharge and dielectric breakdown strength. The loadings of the silica nanofillers were varied at 1, 3, and 5 wt% to identify the most effective nanofillers loading in improving XLPE nanocomposites' durability. The results show that XLPE nanocomposites with 1 wt% silica nanofillers obtained the lowest value of the maximum PD magnitude compared to other compositions. The dielectric breakdown strength of XLPE increased significantly as 1 wt% of silica nanofillers have dispersed. However, the trend was saturated when the nanofiller loading at 3 wt% and slightly decreased at 5 wt% of the nanofiller loading.

Many previous studies used the performance factors for the evaluation of heat transfer enhancement of nanofluids under the identical pumping power. The validity of the performance factors was not examined yet. The validity of the performance factors used in previous studies examined considered only flows in a circular tube based on the empirical correlations and experimental data. It was found that the performance factors used in the previous studies are not valid for the evaluation of heat transfer enhancement of nanofluids. Furthermore, this paper shows that the direct comparison of heat transfer rates without the assumptions of equal surface area and the equal temperature difference is suitable for the evaluation of heat transfer enhancement of single-phase fluids.

PurposeThis paper aims to study the natural convection of a nanofluid inside a cavity which contains obstacles using lattice Boltzmann method (LBM). The results have focused mainly on various parameters such as number and aspect ratio of roughness elements and different nanoparticle volume fraction. The isotherms and streamlines are presented to describe the hydrodynamics and thermal behaviors of the nanofluid flow throughout the enclosure.Design/methodology/approachThe methodology of this paper consists of mathematical model, statement of the problem, nanofluid thermophysical properties, lattice Boltzmann method, LBM for fluid flow, LBM for heat transfer, numerical strategy, boundary conditions, Nusselt (Nu) number calculation, code validation and grid independence.FindingsNatural convection heat transfers of a nanofluid inside cavities with and without rough elements have been studied. Lattice Boltzmann technique has been used as numerical approach. The results showed that at higher Rayleigh number (Ra= 106), there are denser streamlines near the left (source) and right wall (sink) which results in better cooling and enhances convective heat rejection to the heat sink. After a distinctive aspect ratio of rough elements (A = 0.1), change in streamline pattern which arises from increasing of aspect ratio does not have an important effect on isotherms. Results indicate that for lower Rayleigh number (Ra = 103), no variation in average Nu is observed with increasing in number of roughness, while for higher one (Ra= 106) average Nu decreases fromN = 0 (smooth cavity) up toN = 4 and then remains constant (N = 6).Originality/valueCurrently, no argumentative and comprehensive extraction can be concluded without fully understanding the role of different arrangement of roughness. Some geometrical parameters such as aspect ratio, number and position of rough elements have been considered. Also, the effect of nanoparticle concentration was studied at different Ra number. Briefly, using LBM, this paper aims to investigate the natural convection of a nanofluid flow on the thermal and hydrodynamics parameters in the presence of rough element with various arrangements.

The effects of using aqueous nanofluids with the presence of Pentaethylene Glycol-Treated Graphene Nanoplatelets as the working fluids on the thermal performance of flat-plate solar collectors (FPSCs) were investigated experimentally. Water-based nanofluids were prepared with the concentrations of 0.025, 0.05, 0.075, and 0.1 wt%. Then the thermophysical properties were measured. Experimental setup and a MATLAB program were used to study the thermal performance of FPSCs-based nanofluids. The fluid inlet temperatures used in this study were 303, 313, and 323 K, and the flow rates were 0.00833, 0.01667, and 0.025 kg/s. Meanwhile, 500, 750 and 1000 W/m2 were set for the heat flux intensities. As the weight concentration was increased, thermal conductivity, dynamic viscosity, and density also improved, while specific heat decreased. The efficiency of FPSC increased as the flow rate and heat flux intensity were increased. However, the efficiency of FPSC decreased when the temperature of the fluid inlet was increased. Compared to water, the FPSC efficiency recorded an increase of up to 10.7%, 11.1%, and 13.3% for PEG-GNP nanofluids at different mass flow rates. Finally, the regression model was developed through MATLAB to predict the thermal efficiency coefficients of FPSC.

To analyse the effects of cylindrical- and row-trenched cooling holes with an alignment angle of 90 degrees on the film-cooling effectiveness near the combustor end wall surface at a blowing ratio of 3.18, the current research was done. This research included a 3D representation of a Pratt and Whitney gas turbine engine, which was simulated and analysed with a commercial finite volume package FLUENT 6.2.26. The analysis was done with Reynolds-averaged Navier–Stokes turbulence model on internal cooling passages. This combustor simulator was combined with the interaction of two rows of dilution jets, which were staggered in the streamwise direction and aligned in the spanwise direction. In comparison with the baseline case of cooling holes, using row-trenched hole near the end wall surface increased the film-cooling effectiveness 44% in average.

Nanotechnology has emerged to be an essential aspect of science and technology. The growth of this field has been enormous specifically in the development of nanomaterials. Till date, numerous nanomaterials have been developed and designed to suit various applications from mechanical to biomedical. Among the developed nanomaterial, alumina (Al) has been subject of interest due to its notable chemical and physical properties. Specifically, in thermal properties, Al has been shown to have superior thermal conductivity, convective heat transfer coefficient and heat transfer coefficient properties. As such, Al has been utilized in different forms in various fields of applications and verified for its importance, significance and efficiency. Though it had shown outstanding results in the field engineering and sciences, their effect towards the environment and human health is yet to be explored extensively. The present paper aims to review the significance of Al nanoparticle addition in mono- and hybrid nanofluids. Also, this paper intends to provide the reader with an overview of the works that have been carried out using Al nanoparticles and their findings.

The ion exchange method was used to intercalate a poor water-soluble insecticide, isoprocarb into zinc layered hydroxide (ZLH). PXRD analysis indicated the successful intercalation with good crystallinity for the resulting nanocomposite, with a basal spacing of 33.1 Å. FTIR analyses showing the resemblance of an absorption peak of the nanocomposite with the host and the guest anion. The thermal analysis confirmed that the nanocomposite had better thermal stability compared to the pristine isoprocarb. The nanocomposite also characterized by elemental and surface morphology analysis. The surface analyses of the host and nanocomposite showed mesoporous-type material characteristics. On the whole, the intercalation process decreased the pore size of the nanocomposite compared to the pristine host, layered zinc layered hydroxide-sodium dodecyl sulphate (ZLH-SDS). The obtained material is believed has a great potential as an environmentally friendly insecticide. Keywords: Intercalation, Characterization, Zinc layered hydroxide, Isoprocarb, Mesoporous

A novel Cellulose Nanocrystals (CNC) nanoparticles were proposed as green additive as green additives for improving tribological properties of lubricants. Enhanced tribological performance was measured using piston–skirt liner tribometer under variable load, speed and temperature; and varying concentrations of nanoparticles in lubricating oil. Study on a worn surface on the plate was characterized by SEM and EDX. This study shows that the mixing of CNC nanoparticles in engine oil significantly reduces the friction and wear rate and hence improves the lubricating properties of engine oil. Base oil containing 0.1% CNC demonstrates excellent tribological properties including the lowest COF and the strongest wear resistance under all lubrication conditions. An elemental content in EDX analysis reveals that Carbon and Aluminum were the most elements present.

Nano-lubricant is a new kind of engineering lubricant composed of nanometer-sized particle dispersed in a base lubricant. Recently, nanoparticles have been explored as lubricant additives for improving the stability and lubricity properties of a technological fluid. Cellulose nanocrystals (CNC), a unique and natural material extracted from native cellulose, has gained much attention in many field application due to its remarkable physical properties, special surface chemistry, and excellent biological properties, making them attractive as a green lubricant additive. The purpose of this study is to investigate the characterization of the CNC nanoparticles and to evaluate the influence of CNC nanoparticles on the lubricating properties added to the base oil. In this study, CNC nanoparticles were prepared and suspended in five different volume concentrations in the engine oil (0.1, 0.3, 0.5, 0.7 and 0.9%). The kinematic viscosity and viscosity index of the resulting nano lubricant was determined while varying both the nanoparticle volume fraction and the temperature. The size, morphology, and structure of CNC nanoparticles were characterized using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray (EDX) and X-ray diffractions (XRD). The dispersion analysis of CNC nanoparticles in lubricating oil using UV spectrometer confirms that CNC nanoparticles possess good stability and solubility in the lubricant and improve the lubricating properties of the engine oil. The overall results of this experiment reveal that the addition of CNC nanoparticle with base 0il SAE40 lubricant shows the highest value of VI and most suitable concentration for improving properties of the base oil.

In this study, multiwalled carbon nanotubes (MWCNTs) were modified using low frequency (50 Hz) nonequilibrium plasma, which was generated separately by oxygen and nitrogen dielectric barrier discharge plasma (DBD) at atmospheric pressure. The MWCNTs were treated with oxygen and nitrogen DBD plasma at atmospheric pressure under three different applied voltages, because the MWCNTs surface was closely related to the plasma treatment voltage. The surface and electrical properties of pristine and treated MWCNTs were studied using Transmission Electron Microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy, while the electrical characteristics were measured using a Hall measurement and two-point probe. FTIR showed formation of oxygen-containing groups like C=O and COOH for the O2 DBD plasma, and addition of N–H vibration bending for the N2 DBD plasma. Raman spectroscopy revealed that the ratio of I D/I G increased with increasing discharge voltage of plasma. The ascended I D/I G may be ascribed to the production of several new defects owing to the introduction of oxygen- and nitrogen functional groups recognized by FTIR. The results of Hall measurement showed that the hall mobility increased with the increase of O2 and N2 DBD voltage. Highest hall mobility was measured for MWCNTs treated with nitrogen at 12 kV, which was 172.9 cm2/Vs. It was also found from the two-point probe IV curve that Ohmic behaviour of pristine MWCNTs tended to change to Schottky behaviour after DBD plasma treatment.

Many approaches to improve the transformer oil characteristics have been made by adding nanofillers into the liquids, but it has caused the existence of sedimentation and agglomeration thereby resulting in incompatibility of transformer oil. In view of foregoing, this paper aims to study the impact of cetyl trimethyl ammonium bromide (CTAB) surfactant added with the nanofiller in improving the compatibility and agglomeration issues towards improvement of breakdown voltage (BDV) characteristics of oil nanofluids. This study was carried out by implementing three different percentages of silica (SiO2) and alumina (Al2O3) nanofillers along with CTAB as surfactant into the mineral oil. The breakdown voltage test was carried out accordance to IEC 60156 standard. The results show that the inclusion of 0.1 wt% SiO2 and 0.1 wt% Al2O3 nanoparticles into mineral oil have improved the BDV. Meanwhile, Al2O3 nanofluids with 0.075 wt% CTAB had good impact on BDV but not on SiO2. This case has reverse behavior with the sedimentation which 0.1 wt% CTAB in SiO2 nanofluids has a good response but not the whole in Al2O3 nanofluids. This could be mainly due to the limitation stability of the nanofluids.

Palm oil mill secondary effluent (POMSE) has high colour intensity, turbidity and organic load of biochemical oxygen demand which still not achieved the discharged requirement by department of environment and led to detrimental to the aquatic life. Photocatalysis process is one of the promising method in wastewater treatment due to its advantages. This study reports on the POMSE treatment using photocatalysis process in presence of ZnO-polyethylene glycol (ZnO-PEG) nanoparticles. The characterization results using fourier-transform infrared spectroscopy, X-Ray diffraction and transmission electron microscopy show that there are no impurities present in the samples and presenting the nature and chemical bonds of ZnO-PEG besides having less agglomeration and smaller average in size (25–150 nm) compared to commercial ZnO (25–200 nm). ZnO-PEG nanoparticles have a great potential in degradation of POMSE and this is supported with the results obtained from the experimental works. Four potential factors which are different type of (A) photocatalysts, (B) pH of the POMSE, (C) ZnO-PEG loading and (D) concentration of POMSE were evaluated for the significance design of experiment. It is found that all the main factors were significant, with contributions of (A)66%, (B)73%, (C)84% and (D)84% respectively, to the POMSE degradation. Accordingly, the most favorable condition for the photocatalysis degradation process of POMSE is under pH 6.5 in presence of 0.5 g/L ZnO-PEG for the 50% of POMSE dilution. It is believed that this integrated approach can be implemented in the industry to achieve discharged standard of POMSE and maintain the green environment for future generation.

Microchannel heat sinks are used to remove high heat flux generated by electronic components. Microchannel heat sink has gained huge attention from former researchers due to its capability to enhance the heat transfer performance. However, the conventional design such as microchannel heat sink with rectangular channel becomes inadequate to remove very high heat flux due to thermal boundary layer thickness. In this paper, the effectiveness of secondary channel that implemented to the novel design which constructed by cavities and ribs are studied numerically for Reynolds number (Re) ranging from 100 to 450. The performance of proposed design (TC-RR-SC) is investigated by using a comparative analysis with related geometry such as microchannel with rectangular rib (CR-RR), microchannel with triangular cavity (TC) and microchannel with rectangular rib and triangular cavity (TC-RR). The result shows that TC-RR-SC design has an extraordinary overall performance compared to other designs due to combined effect of thermal boundary layer re-development and flow mixing in main channel. Besides that, the design shows the less flow and heat transfer irreversibility that contributed to thermal performance from the view of the second law of thermodynamics.

In this paper, cellulose nanocrystal (CNC) – ethylene glycol (EG) + Water (W) based nanofluid was developed and assessed for their thermophysical properties and the usefulness towards machining performances. The nanofluid was prepared by adopting two-step preparation method and at volume concentration of 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3% and 1.5%. The nanofluid with 1.3% and 1.5% concentration showed to have superior the conductivity properties, around 0.559 W/m·K at 70 °C. However, the 0.5% concentration has the highest stability with 0.52 W/m·K at 70 °C. The 0.5% nanofluid concentration was then selected for the machining performance evaluation. The machining performance was evaluated by using a lathe machining operation to determine the heat transfer and tool life properties. The cutting variables such as cutting speed, depth of cut and feed rate are varied to understand the effect of developed nanofluid on the machining bahaviour. Findings revealed that the tool failure on machining using MWF is flank wear, chipping and abrasion and fractured at the maximum cutting distance of 500 mm. However, machining using CNC-EG+W nanofluid revealed the tool failure to be flank wear, adhesion and build- up-edge (BUE) and fractured at the maximum cutting distance of 772 mm.

Palm oil mill secondary effluent (POMSE) has a high color intensity, dissolve oxygen, turbidity, and an organic load of BOD which still not achieved the discharged requirement by the Department of Environment (DOE) and led to detrimental to the aquatic life. The photocatalytic degradation process is one of the promising methods in wastewater treatment due to its advantages. However, the study on POMSE treatment using the photocatalytic degradation process in the presence of ZnO-PEG nanoparticles (NPs) is still limited. Therefore, this study reports on the photocatalytic degradation of POMSE by using ZnO-PEG NPs. The ZnO-PEG NPs was characterized by using XRD and FTIR where the results show that there are no impurities present in the samples and presenting the nature and chemical bonds of ZnO-PEG 30nanoparticle. Then, the optimization of the photocatalytic degradation of POMSE in a UV-activated ZnO system based on central composite design (CCD) in response surface methodology (RSM) was determined. ZnO-PEG NPs have a great potential in degradation of POMSE and this is supported with the results obtained from the experimental works. Three potential factors which are initial pH of POMSE (A), Loading of ZnO-PEG (B), and concentration of POMSE (C) were evaluated for the significance design of experiment. It is found that all the three main factors were significant, with contributions of 34.5% (A), 79% (B), and 82% (C) respectively, to the POMSE degradation. Accordingly, the optimum condition for the photocatalysis degradation process of POMSE is under pH 6.5 in presence of ZnO-PEG with 0.08 g/L for the 25% of POMSE concentration. Then, the photocatalytic activity mechanism of ZnO-PEG nanoparticle was studied by using the kinetic study. It is believed that this integrated approach can be implemented in the industry to achieve discharged standard of POMSE and maintain the green environment for future generation.

The complex physics and biology underlying intracranial hemodynamics are yet to be fully revealed. A fully resolved direct numerical simulation (DNS) study has been performed to identify the intrinsic flow dynamics in an idealized carotid bifurcation model. To shed the light on the significance of considering blood shear-thinning properties, the power-law model is compared to the commonly used Newtonian viscosity hypothesis. We scrutinize the kinetic energy cascade (KEC) rates in the Fourier domain and the vortex structure of both fluid models and examine the impact of the power-law viscosity model. The flow intrinsically contains coherent structures which has frequencies corresponding to the boundary frequency, which could be associated with the regulation of endothelial cells. From the proposed comparative study, it is found that KEC rates and the vortex-identification are significantly influenced by the shear-thinning blood properties. Conclusively, from the obtained results, it is found that neglecting the non-Newtonian behavior could lead to underestimation of the hemodynamic parameters at low Reynolds number and overestimation of the hemodynamic parameters by increasing the Reynolds number. In addition, we provide physical insight and discussion onto the hemodynamics associated with endothelial dysfunction which plays significant role in the pathogenesis of intracranial aneurysms.

Hydrogen has attracted global attention as a clean secondary energy source and has numerous possible applications, including fuel for vehicles. To store the hydrogen effectively, ammonia is considered promising due to high hydrogen density, stability, and total energy efficiency. Adopting ammonia as a fuel in vehicles requires a proper fuel tank design to fulfill the required volumetric content and safety standards, without neglecting the economic objectives. In general, a type-IV pressure vessel is utilized as a fuel tank because it is the lightest one, compared to other types of pressure vessel. This paper focuses on the effort to develop a lightweight type-IV ammonia pressure vessel designed for mobility vehicles. The material combination (liner and composite) and composite stacking sequence are analyzed for both burst and impact tests by using a finite element method. Two polymer materials of polyethylene terephthalate (PET) and polypropylene (PP) are evaluated as the liner considering their ultimate tensile strength, density, cost, and compatibility with ammonia, while carbon-fiber-reinforced polymer (CFRP) and glass-fiber-reinforced polymer (GFRP) are adopted as composite skins. In addition, five composite stacking sequences are analyzed in this study. Von Mises stress and Hashin&rsquo, s damage initiation criteria are used to evaluate the performance of liner and composite, respectively. As the results, PP-based pressure vessels generate lower stress in the liner compared to PET-based vessels. In addition, CFRP-based pressure vessels have a higher safety margin and are able to generate lower stress in the liner and lower damage initiation criteria in the composite skin. The material combination of PP-CFRP with a stacking sequence of [90/&plusmn, 30/90]3s gives the lowest maximum stress in the liner during the burst test, while, for the impact test, the stacking sequence of [90/&plusmn, &theta, /90]3s is considered the most appropriate option to realize a lower stress at the liner, although this tendency is relatively small for vessels with PP liner.