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Purpose The aims of this study is to numerically investigate the thermal phenomena during magnetohydrodynamic (MHD) free convection in an oblique enclosure filled with porous media saturated with Cu–Al2O3/water hybrid nanofluid and heated at the left wavy wall. The thermophysical phenomena are explored thoroughly by varying the amplitude (λ) and undulation (n) of the wavy wall and the inclination of the enclosure (γ) along with other pertinent physical parameters. Darcy–Rayleigh number (Ram), Darcy number (Da), Hartmann number (Ha) and nanoparticle volumetric fraction (ϕ). The effect of all parameters has been analyzed and represented by using heatlines, isotherms, streamlines, average Nusselt number and local Nusselt number. Design/methodology/approach The finite volume method is used to work out the transport equations coupled with velocity, pressure and temperature subjected to non-uniform staggered grid structure after grid-sensitivity analysis by an indigenous computing code and the semi-implicit method for pressure linked equations (SIMPLE) algorithm. The solution process is initiated following an iterative approach through the alternate direction implicit sweep technique and the tridiagonal matrix algorithm (TDMA) algorithm. The iterative process is continued until successive minimization of the residuals ( Findings This study reveals that the increase in the heating surface area does not always favor heat transfer. An increase in the undulation amplitude enhances the heat transfer; however, there is an optimum value of undulation of the wavy wall for this. The heat transfer enhancement because of the wall curvature is revealed at higher Ram, lower Da and Ha and lower volume fraction of nanoparticles. In general, this augmentation is optimum for four undulations of the wavy wall with an amplitude of λ = 0.3. The heat transfer enhancement can be more at the cavity inclination γ = 45°. Research limitations/implications The technique of this investigation could be used in other multiphysical areas involving partial porous layers, conducting objects, different heating conditions, wall motion, etc. Practical implications This study is to address MHD thermo-fluid phenomena of Cu–Al2O3/water-based hybrid nanofluid flow through a non-Darcian porous wavy cavity at different inclinations. The amplitude and number of undulations of the wavy wall, permeability of the porous medium, magnetic field intensity, nanoparticle volumetric fraction and inclinations of the enclosure play a significant role in the heat transfer process. This analysis and the findings of this work can be useful for the design and control of similar thermal systems/devices. Originality/value Many researchers have examined the problem of buoyancy-induced free convection in a wavy-porous cavity packed with regular fluids or nanofluids. However, the effect of magnetic fields along with the amplitude (λ) at different undulations (n) of the heated wavy wall of an inclined enclosure is not attended so far to understand the transport mechanisms. Most often, the evolutions of the thermo-fluid phenomena in such complex geometries invoking different multiphysics are very intricate. Numerical implementations for simulations and subsequent post-processing of the results are also challenging.

In this contribution, the investigation conducted on alternative fuels includes methanol 20% blended with gasoline 80% and emulsion-based fuel with the composition of gasoline 80%, ethanol 15%, and H2O 5% are compared with 100% conventional gasoline fuel. These fueled single-cylinders spark ignition engine is studied for checking their performance and emission characteristics as per future emission norms. This work is performed on One-dimensional AVL Boost Simulation Software. The simulations predicted the performance and emission characteristics were far lesser than conventional 100% gasoline. These fuels meet the strict emission regulations of Euro VII. The main purpose of this investigation is to use alternative fuels to improve the performance and emission characteristics of the single- cylinder spark ignition engine and reduce the consumption of fossil fuel reserves. This investigation led to the conclusion that by using methanol 20% in 80% gasoline and micro-emulsion, fuel improves the power, BSFC (brake specific fuel consumption), thermal efficiency and combustion properties of the single-cylinder spark-ignition engine. The CO, HC and NOx emissions were also reduced for alternative fuel than 100% gasoline fuel. The novel water-based emulsion fuel showed the lowest value of NOx emissions as compared to blended 20% methanol with 80% gasoline and 100% gasoline fuel.

In this research, the effect of nanofluids including graphite and water on the heat transfer enhancement in heat Exchangers with both straight and rotational inner tube were examined. Nano-fluids including graphite and water were obtained at 0.01, 0.02 and 0.03 %volume concentrations by means of pure water as a base fluid. The aim of the study is to experimentally investigate and compare the influence of straight inner tube on the performance of a double tube heat exchanger at different flow rates, different capacity ratios (0.25, 0.5, 0.75, 1), different rotation rates (0 RPM, 100 RPM, 150 RPM, 200 RPM, 300 RPM, 500 RPM and 750 RPM) and by using nanofluid including graphite and water volume at values of 0.01, 0.02, 0.03%. In the experiments the flow is turbulent. In order to determine the heat transfer enhancement, the experimental datas were compared for pure water and nano-fluids. According to the results, Nusselt number, pressure loss, efficiency of heat exchanger were gauge. By the results achieved from experiments, correlations for Nusselt number have been reproduce and experimental data have been compared with ones in the literature by drawing graphics. The experiment that provides the best increase in heat transfer is the nanofluid including 0.02% volume concentrations of graphene/water at 500RPM speed.

Waterborne polyurethane (WBPU) has the advantages of environmental, excellent film‐forming property and high bonding strength. However, the mechanical strength of waterborne polyurethane in coating products is not enough, and its wear resistance and softness are poor. In this paper, the Cellulose Nanocrystals (CNC) AQ3 obtained by acid hydrolysis of microcrystalline cellulose was successfully dispersed in the waterborne polyurethane matrix to prepare nanocomposite films with different contents. The mechanical properties, thermal properties, wear resistance and softness of the nanocomposite films were studied by Thermogravimetric (TG), tensile test, dry friction test and KES test. The morphology of CNC dispersed in waterborne polyurethane matrix was studied by Scanning electron microscope (SEM). The results show that the lower content of CNC was uniformly dispersed in the waterborne polyurethane matrix and the interaction between the two forms hydrogen bonds. Compared with waterborne polyurethane, the initial degradation temperature of the nanocomposite films made by adding only 1 wt% CNC increased by 50°C, the tensile strength increased by 179.3%, the wear resistance increased by 19%, and the minimum bending stiffness B reached 0.161 (gf·cm2). The results of this study can be used for textile coating applications, such as polyurethane synthetic leather.

Background: Researchers working in the field of nanofluid have done many studies on the thermophysical properties of nanofluids. Among these studies, the number of studies on specific heat is rather limited. In the study of the heat transfer performance of nanofluids, it is essential to raise the number of specific heat studies, whose subject is one of the important thermophysical properties. Objective: The authors aimed to measure the specific heat values of Al2O3/water, Cu/water nanofluids and Al2O3-Cu/water hybrid nanofluids using the DTA procedure, and compare the results with those frequently used in the literature. In addition, this study focuses on the effect of temperature and volume concentration on specific heat. Methods: The two-step method was tried to have nanofluids. The pure water selected as the base fluid was mixed with the Al2O3 and Cu nanoparticles and Arabic Gum as the surfactant, firstly mixed in the magnetic stirrer for half an hour. It was then homogenized for 6 hours in the ultrasonic homogenizer. Results: After the experiments, the specific heat of nanofluids and hybrid nanofluid were compared and the temperature and volume concentration of specific heat were investigated. Then, the experimental results obtained for all three fluids were compared with the two frequently used correlations in the literature. Conclusion: Specific heat capacity increased with increasing temperature, and decreased with increasing volume concentration for three tested nanofluids. Cu/water has the lowest specific heat capacity among all tested fluids. Experimental specific heat capacity measurement results are compared by using the models developed by Pak and Cho and Xuan and Roetzel. According to experimental results, these correlations can predict experimental results within the range of ±1%.

As an unconventional fluid medium, nanofluid has outstanding advantages in thermal conductivity and stability, which can not only be applied in the frontier field of engineering, but also bring technological innovation to the traditional manufacturing and construction industries. However, the water-based nanofluid has the problem of poor stability, leading to nanofluid failure and severely limiting the development of nanofluid. In this paper, the ‘Two-step method’ was used to prepare SiO2 nanofluid with mass fractions of 0.5%, 1.0%, and 1.5%. The stability of the SiO2 nanofluid was determined by four characterization methods: visual observation, absorbance test, viscosity test andsurface tension test. Finally, the three-stage time-varying process on stability of the water-based SiO2 nanofluid was proposed. The results showed that the initial stability of the nanofluid was worse with increasing concentration. This conclusion was in good agreement with the theoretical derivation. Moreover, the stability of the nanofluid still exhibited this characteristic in the period of 0–8 days. This study can provide useful information for revealing the nanofluidic stability theory and support the further development of nanofluid technologies

The effectiveness of solar collector using conical strip inserts with Al2O3/Deionized (DI) water nanofluids is presented in this paper. The experiments were conducted under various volume concentra...

Al2O3 and TiO2 water based nanofluids were used in heat exchangers to enhance the nusselt number. Tests were performed at different flow rates ranging between 2 LPM and 4 LPM. Concentrations of nanoparticles were taken from 0.1% to 0.3% by volume. Shell & tube heat exchangers having 14 tubes and Double pipe heat exchanger were used. The enhancement in Nusselt number and Reynolds number for Al2O3 and TiO2 nanofluids and heat exchangers were determined and compared. It was found that the increment of Nusselt number was more for Al2O3 nanofluid as compared to TiO2 nanofluid for both heat exchangers.

This investigation is based on the fabrication and characterization of nano-biocomposites made from natural resources like jute and soy seeds along with glutaraldehyde as curing agent. Water based soy resin was modified with different weight percentages of natural and organically modified nanoclay and applied as matrix along with jute to prepare the nanocomposites. Composites were degraded under soil burial condition and lost 60–75% of their original weight after 60 days. These composites were characterized from various aspects like thermal stability, mechanical testing and fire retardancy to ensure them to be used for end application like furniture, and automobile interiors.

A new metal–organic framework (MOF) compound [Mn2(2,2′-bca)2(H2O)2]n (Mn-MOFs) was successfully synthesized by solvothermal method, and Mn-MOFs@Zn material was prepared by loading zinc phosphate onto Mn-MOFs by ball milling, then Mn-MOFs@Zn was added to the water-based acrylic paint to prepare Mn-MOFs@Zn@acrylic coating. The AC impedance test results showed Mn-MOFs@Zn@acrylic coating has higher corrosion inhibition performance and stability to mild steel when compared with blank coating. The impedance modulus of the blank coating in the low frequency region decreased by 90%, and the Rct showed a trend of first increasing and then decreasing over time, the maximum Rct was only 303.8 Ω, which was only Mn-MOFs@Zn@acrylic coating one-seventh of the Rct value. The artificial scratch experiment showed that the Mn-MOFs@Zn@acrylic coating only slightly corrodes at the scratches, because Mn-MOFs@Zn material made the coating a self-repairing function and improved the durable anticorrosion performance of the acrylic coating.

This study synthesized the water-permeable and hydrophobic property of water-based polyurethane (WPU) and applied it to nylon fiber-based functional textiles. Specifically, poly-stearyl acrylate (PSA) homopolymers with different molecular weights were used as end-capping agents in the WPU to form water-based polyurethane with acrylate terminal (WPUA). In the WPUA process, dimethylacetamide was adopted as a neutralizing agent to form a stable WPUA emulsion. The effects of the design parameters, such as the hydrophilic ionic group dimethylol propionic acid (DMPA), the PSA molecular weight and content, were set as the control factors and are analyzed by the Taguchi method and gray relational analysis (GRA). The water-repellent characteristic, water vapor permeability (WVP) and fabric flexural rigidity were considered as performance parameters as multi-qualities. The Taguchi method was based on the analysis of variance and implemented orthogonal arrays for experimental design. Each performance parameter was optimized independently. Then, the performance parameters were optimized together with GRA. According to the experimental results, the most important factor for the water-repellent characteristic, WVP and fabric flexural rigidity is the DMPA content, followed by the PSA molecular weight and content. The corresponding results showed that in the optimal parameter combination, the content of DMPA was 30.8 phm (parts per hundred monomer by weight), the PSA molecular weight was 3000 g/mol and the PSA content was 4 phm. After WPUA padding, the water contact angle of the water-repellent nylon was 135.3°, the WVP was 2271.7 g/m2/day and the flexural rigidity was 2.7 cm.

A systematic approach was used to investigate the weathering-induced degradation of a common water–based intumescent coating. In this study, the coatings are intended for humid indoor applications on steel substrates. The coating contains ammonium polyphosphate, pentaerythritol, melamine, and polyvinyl acetate. By replacing each ingredient with a less water-soluble substance, the most vulnerable substances, polyvinyl acetate and pentaerythritol, were identified. Furthermore, the weathering resistance of the system was improved by exchanging the ingredients. The coatings were stressed by artificial weathering tests and evaluated by fire tests. Thermogravimetry and Fourier-transform infrared spectroscopy were used to study the thermal decomposition. This study lays the foundation for the development of a new generation of water-based intumescent coatings.

The influence of the heat pipe orientation and the working fluid type of the screen mesh wick heat pipe was investigated experimentally. A hybrid nanofluid using three proposals for composite nanop...

In this work, the influence of the drop volume and applied magnetic field on the wetting features of water-based ferrofluids, is experimentally investigated. Firstly, water drops with volume in the range of 0.1–100 micro-liters are placed, by using micro-pipettes, on bare and coated acrylic plates, to gain reference data concerning the contact angle. Then, drops of water-based ferrofluid, with the volume ranging from 1 to 10 micro-liters, are set on bare acrylic plates, which are placed into the uniform magnetic field created, in normal direction to the plate, by using permanent magnets. Since the ferrofluid drops are elongated along the magnetic field, the contact angle increases at augmentation of the magnetic flux. Besides, when a critical magnetic flux is exceeded, ferrofluid drop loose contact with the plate and jumps towards the magnet. A heuristic equation to predict the fluctuation of the liquid surface tension versus the drop volume, and also versus the ratio of the applied magnetic field energy to the kinetic energy of the magnetic particles dispersed into the water-based ferrofluid, is suggested.

This study intends to explore the lubrication mechanism of hexagonal boron nitride nano-additive. Synergistic analysis comprising worn surface observation, surface wettability testing, and the Stribeck curve principle is used to test this water-based lubricant on steel–steel contact. Distilled water and 0.1–5.0 vol.% hexagonal boron nitride nano-additive is used to prepare a mixture using sonification technique. A viscometer is employed to determine the viscosity of the nanolubricant. A four-ball tribometer is employed to determine the tribological characteristics and lubrication performance. Hamrock and Dowson equations are used to determine the minimum film thickness needed for lubrication. Surface morphology characteristics are inspected using energy-dispersive X-ray spectroscopy, scanning electron microscopy, surface tension meter, and profilometer. The efficacy of the lubricant as friction and wear-reduction additive is determined to have a mixed lubrication regime with the optimum concentration of 1.0 vol.% hexagonal boron nitride. Protecting film, mending effect, rolling effect, and polishing effect have been recommended as the lubrication mechanisms. Increasing the addition of hexagonal boron nitride additives may lead to a change in the lubrication regime from mixed to hydrodynamic, where agglomeration is observed in the nanoparticles, and an increase in friction is observed.

In an effort to reduce negative feedback resulting from temperature fluctuations, house floors are commonly laid with laminate flooring. The aim of this study was to study the thermal insulation properties and adhesion strength of the water-based insulation paint mixed with hollow glass spheres and applied onto the laminate flooring. The objective was to determine whether a prepared insulation paint mixture can be used instead of backing paper. For this purpose, two different laminate flooring samples were used. In the first case, the upper surface of the sample was coated with decorative paper and the lining surface was coated with backing paper. The upper surface of the second sample was coated with decorative paper and the lining surface was not coated with backing paper. Then, insulation paint mixture was applied 2, 4, or 6 times to the lining surfaces of both groups, and experimental results were obtained. As the number of layers was increased, the insulation mixture applied to the lining surfaces of the test samples was found to contribute positively to thermal insulation and adhesion resistance of specimens.

Smart containers can be produced with polyelectrolyte multilayers that can release inhibitors in response to environmental changes at the coating defects. In this study, mesoporous TiO2 hollow sphe...

In this study, based on a viscosity and gel-strength improving agent synthesized in a laboratory, a weak-gel-type clay-free and water-based drilling fluid was developed experimentally to optimize t...

In this paper, the cross-linked micro-gel polymer between acrylamide (AM) and N, N-Methylenebisacrylamide (MBA) was synthesized by dispersion polymerization. The initiator and crosslinking agent concentration were used to control the particle size of micro-gel polymer. The filtration property and mechanism of micro-gel were investigated comprehensively. The characteristics of micro-gel were checked by means of Fourier transform infrared spectroscopy, thermogravimetry, transmission electron microscopy, and particle size distribution, respectively. The results indicated that the cross-linked micro-gel polymer exhibited several outstanding merits, such as thermal stability (up to 200 °C), filtration control and rheological property. Microstructure analysis and particle size distribution examinations showed that the scale of micro-gel polymer was micro, which is in accord with design. Rheological tests demonstrated that the nonlinear structure of micro-gel polymer showed less impact on the apparent viscosity. The anti-high temperature property of micro-gel polymer was better than poly anioniccellulose (PAC) and asphalt widely applied in drilling fluid for anti-high temperature fluid-loss additive. As a result, the cross-linked micro-gel polymer had great potential to be applied in high temperature water-based mud.

Purpose The purpose of this paper is to study the tribology behavior of steel–steel contact under the lubrication of water-based drilling mud with different oleic acid-filled microcapsules as lubricant additives. Design/methodology/approach A ball-on-disc tribometer was used to evaluate the lubrication properties of the steel–steel contact. The wear tracks of the worn surfaces were observed by a scanning electron microscope. Findings Results show that the dependence of both friction and wear on the category of additives shares a consistent pattern. In contrast to oleic acid and empty microcapsules, oleic acid-filled microcapsules achieve the best tribological performance which is related to the lubricant effect of oleic acid and the isolation and rolling abilities of microcapsules. Practical implications This study provides a helpful method of encapsulated lubricant additives to prolong lubrication performance for steel–steel contact. Originality/value This study has applied microcapsules to improve the tribological properties of drilling mud. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0320/

The kinematic viscosity of three kinds of nanofluids namely Al2O3/water, TiO2/water, and graphene/water was measured at different temperatures. Concentration of the metallic oxide nanoparticles in ...

Compliant polishing (e.g. bonnet polishing) is widely used to finish freeform surfaces. However, direct pad/surface contact often causes scratches or embedding of abrasives, especially on metal moulds. Here, the use of non-Newtonian fluid (polymer and starch) to enable contactless polishing without need for a polishing pad is reported. Modelling and analysis are conducted to reveal the influence of fluid rheology on the material removal mechanism. Using #6000 grit alumina, Gaussian shaped removal footprints can be obtained, with a completely scratch-free roughness of 3.9 nm Ra on Nickel, in contrast with 70.3 nm Ra obtained by general water based bonnet polishing.

Thermal-hydraulic characteristics of water based ZrO2 nanofluids has been investigated in a segmental baffled shell and tube heat exchanger in turbulent flow regime. The effect of Reynolds number, nanoparticle loading, mass-flow rate, and tube lay-out has been analysed on overall heat transfer coefficient. The effect of Reynolds number on the tube side pressure drop and convective heat coefficient have also been discussed. The effect of shell side mass-flow rate was also investigated on shell side heat transfer coefficient determined using Bell-Delaware method. The nanoparticle volume concentration is taken very low i. e. 0.2%, 0.4%, and 0.8%, respectively. The improvement in both tube side convective heat transfer coefficient and overall heat transfer coefficient has been observed. The maximum improvement in the convective heat transfer coefficient is found to be 14.1% for 0.8% ZrO2 nanofluids. However, the percentage enhancement in tube side pressure drop was higher than the percentage increment in the tube side heat transfer coefficient.

In present work, five different nanoparticles of three different shapes are used to study the enhancement in thermal conductivity, viscosity and stability of nanofluids. The main objective of present work is to analyze the effect of shape on thermo-physical properties of nanofluids. For this study, spherical, cubic and rod shaped nanoparticles are used. CuO, MgO, TiO2, ZrO2 and Al2O3 water based nanofluids are prepared by two step method using probe sonication technique. The effect of shape on thermal conductivity of nanofluids is analyzed experimentally by using hot-wire method set up. Results of this study reveal that the cubic shaped Al2O3 nanofluid (concentration 2.5 wt%) shows highest thermal conductivity over base fluid by 3.13 times. Effect of nanoparticle shape on the viscocity is also studied in the presnt work. Al2O3 nanofluid also has good stability amongst all nanofluids. Also, it is observed that in all five cases of nanofluid cubic shape nanoparticles enhance thermal conductivity at the highest rate than spherical and rod shape. Pumping power study shows that cubic shaped nanoparticles require higher pumping power than spherical and rod shaped nanoparticles.

A complete overview of the rheology and filtration properties of drilling fluids is essential to ensure an efficient transport process with minimized fluid loss. Silica nanoparticle is an excellent additive for rheology and filtration properties enhancement. Existing correlations are not available for nano-SiO2-water-based drilling fluid that can extensively quantify the rheology or filtration loss of nanofluids. Thus, two data-driven machine learning approaches are proposed for prediction, i.e., artificial neural network (ANN) and least square support vector machine (LSSVM). Parameters involved in the prediction of shear stress are SiO2 concentration, temperature, and shear rate, whereas SiO2 nanoparticle concentration, temperature, and time are the inputs to simulate filtration volume. A feed-forward multilayer perceptron is constructed and optimized using the Levenberg–Marquardt learning algorithm. The parameters for the LSSVM are optimized using couple simulated annealing (CSA). The performance of each model is evaluated based on several statistical parameters. The predicted results achieved R2 (coefficient of determination) value higher than 0.99 and mean absolute error (MAE) and mean absolute percentage error (MAPE) value below 7% for both the models. The developed models are further validated with experimental data that reveals an excellent agreement between predicted and experimental data.

In suspension plasma spraying (SPS); the use of water based suspensions provides a cheaper; safer and more environmentally friendly alternative to organic liquids. However; due to the physical properties of water; producing a water based SPS coating with desirable microstructure has so far been elusive. In this study; the effects of pH and dispersant on the rheology and stability of YSZ water based suspensions were investigated. PEI; PBTCA and α-Terpineol were used as dispersant polymers. The stabilized suspensions were deposited by Axial III plasma spray system and the relationship between suspension parameters and the atomized droplet size and the final coating microstructure was studied. The results showed that a combination of Terpineol dispersant with pH adjustment to 2.5; could lead to a SPS coating with columnar microstructure having 17.4 vol.% porosity.

This study looks at the effects of different kinds of nanoparticles including AL2O3, SiO2, and CuO on the design of a solar flat plate collector in different volumetric concentrations. Water was used as the base fluid, and optimal SFPC parameters were obtained for each of the nanofluids. Both the efficiency and total annual cost were selected as objective functions, and the optimum Pareto fronts were compared with those of the base fluid. The results show a significant enhancement in both the efficiency and TAC for all the studied nanofluids compared with the pure water as the working fluid. The efficiency improved by 4.47%, 4.65%, and 5.22% in the cases of AL2O3, SiO2, and CuO compared with base fluid with a fixed TAC of 67 $ year−1. With a fixed efficiency of 0.564, TAC decreased by 25.45%, 25.87%, and 27.88%, respectively. The optimum design parameters show that lower heat transfer surface area and insulator thickness are needed for CuO compared with the other cases, followed by SiO2, AL2O3, and the base fluid. In the optimum conditions, a lower particle volumetric concentration is required for CuO, followed by Al2O3 and SiO2.

A novel experimental method was developed through a ball-on-disk tribometer to study the friction and wear behaviour of a chrome steel at temperatures of 25, 200 and 500 °C. Water-based nanolubricants containing different concentrations of nano-TiO2 from 0.4 to 8.0 wt% were used to investigate their effects on friction-reduction and anti-wear mechanisms, in comparison to the benchmarks under dry and water conditions. The results show that the water-based nanolubricants can significantly reduce coefficient of friction (COF) and improve wear resistance of the chrome steel at both ambient and elevated temperatures. In particular, the use of nanolubricant containing an optimal concentration (4.0 wt%) of nano-TiO2 leads to the lowest COF and the smallest ball wear among all the lubrication conditions. The friction-reduction and anti-wear mechanisms are ascribed to the rolling & polishing effects, semisolid film and solid layer contributed by the nano-TiO2 at temperatures of 25, 200 and 500 °C, respectively.

In this paper, EG of different concentration was added in water to form PCM with different freezing point. Then, 0.0625%, 0.125%, 0.25% and 0.5% MCNT was dispersed in to each EG-water basefluids respectively. The latent heat are 160.0, 141.0, 102.0 and 85.5 J/g and melting point are -12.2, -15.7, -22.1 and -25.4 oC for 15%~30% EG-water basefluids. We found that adding MCNT has very little influence on the latent heat and melting point because the total amount of MCNT is very small. Also, we noticed that thermal conductivity will increase with increasing amount of MCNT concentration in EG-water basefluids. An interesting observation is that the enhancement of thermal conductivity was much greater in solid state samples than liquid state samples. For example, in 0.5% MCNT sample, the enhancement of thermal conductivity in solid state was observed over twice higher than that in liquid state.

For reasons of personal health and the environment, consumers are searching for “green” products. Packaging producers and consumers are seeing increased regulations set by authorities for packaging material and waste. Thus, interest in the development of renewable, sustainable fiber-based packaging products is growing. In recent years the paper industry has focused on finding substrates and the chemical suppliers have focused on developing different coating media to enhance properties. Sustainable paper and board barrier products are needed to create an alternative to the use of conventional packaging solutions containing plastics, perfluorocarbon, and wax. Typically, products with a water-based barrier coating are more expensive than conventional packaging solutions. Therefore, to make the new products with water-based barrier coatings cost competitive, the best achievable performance with the lowest coat weight is important so that production costs can be kept as low as possible. Results from pilot trials are presented that consider base stock (pretreated and non-pretreated), application methods by long- and short- (zero) dwell, and metering by rod and resilient tip. Laboratory evaluations of the coverage and barrier performance indicate the proper direction for obtaining a barrier.

This research is a novel experimental work on cooling solar panels using hydrogel beads saturated with Al2O3 water based nanofluid. Nanofluid of concentrations 0.1, 0.25, and 0.5% wt. were used and compared to the water only cooled and the uncooled PV panels. A passive cooling system was created with three layers of the nanofluid saturated hydrogels and attached to the back surface of the exposed PV panels, with fixed radiation intensities of 800 and 1000 W/m2. Using 0.5%wt. Al2O3 water based nanofluid saturated hydrogels, the temperature of the panel was reduced by approximately 17.9 °C and 17.1 °C for radiation intensities of 800 and 1000 W/m2 respectively, compared to the uncooled one. From a performance point of view, 0.5% wt. gave the optimum performance; however, due to the price on the nano materials, 0.25% wt. concentration is the optimum economical selection. The economic analysis showed that the payback period, using 0.25% wt. nanofluid concentration, was 12 years for 1000 W/m2. The annual power generated showed improvement of approximately 10.1% at both tested intensities compared with the uncooled panel. The environmental analysis showed that using the proposed system and the optimised nanofluid concentration can reduce the annual CO2 emission by 7.95 tonnes and 9.76 tonnes for a solar farm of 100 square meter area at radiation intensities of 800 and 1000 W/m2.

The transfer rate of gravure water-based ink is one of the key factors to ensure the quality of printing production. The influencing factors of ink transfer in gravure printing are analyzed. The printing pressure changes the gap between the ink and the substrate so as to adjust the capillary action strength. Thereby the ink transfer rate is changed. Printing speed affects the ink transfer rate by changing the transfer time of the ink in the contact area. When the viscosity of the ink changes, the amount of ink obtained in the net hole will change, and the transfer rate will also change. The ink transfer process was simulated by FLUENT software. The ink transfer volume under four printing pressure, at six different printing speed and with seven different viscosity was analyzed respectively and the optimum parameters were given. The results show that the transfer rate increases with the increase of pressure and the transfer rate decreases with the increase of rotating speed and the viscosity of the ink.

Background: The aim of this study is to determine the surface roughness and adhesion strength of water-based varnishes modified with nanoparticles of zinc oxide (ZnO) and hollow ceramic spherical (HCS) against accelerated UV aging effect in some ThermoWood materials. For this purpose, American ash (Fraxinus americana) and scotch pine (Pinus sylvestris Lipsky) wood were heat treated at a temperature of 190 °C for 1.5 hours and 212 °C for 2 hours. The heat-treated samples were applied with two-component water-based varnishes, with D70 - D99 commercial codes, modified with 1%, 3% and 5% ZnO and HCS nanoparticles individually then these samples were subjected to accelerated aging for 240 hours according to ASTM G154. The surface roughness of varnish layers was determined by TS 6956 EN ISO 4287/A1 and surface adhesion strength by ASTM D4541 principles. Results: The results showed that the nanoparticles generally decreased the surface roughness and adhesion strength in water based varnishes. But surface roughness increased in additives of 5% HCS in D99 and 1% ZnO in D70. Also adhesion strength increased in additives of 5% ZnO and 1% and 5% HCS in D70. Conclusion: The layer properties of water-based varnishes can be improved with ZnO and HCS nanoparticles against aging effects.

The shape and the actuation capability of state of the art robotic devices typically relies on multimaterial systems from a combination of geometry determining materials and actuation components. Here, we present multifunctional 4D-actuators processable by 3D-printing, in which the actuator functionality is integrated into the shaped body. The materials are based on crosslinked poly(carbonate-urea-urethane) networks (PCUU), synthesized in an integrated process, applying reactive extrusion and subsequent water-based curing. Actuation capability could be added to the PCUU, prepared from aliphatic oligocarbonate diol, isophorone diisocyanate (IPDI) and water, in a thermomechanical programming process. When programmed with a strain of epsilon(prog) = 1400% the PCUU networks exhibited actuation apparent by reversible elongation epsilon'(rev) of up to 22%. In a gripper a reversible bending epsilon'(rev)((be)(nd)()) in the range of 37-60% was achieved when the actuation temperature (T-high) was varied between 45 degrees C and 49 degrees C. The integration of actuation and shape formation could be impressively demonstrated in two PCUU-based reversible fastening systems, which were able to hold weights of up to 1.1 kg. In this way, the multifunctional materials are interesting candidate materials for robotic applications where a freedom in shape design and actuation is required as well as for sustainable fastening systems.