A one-pot fractionation method of Moso bamboo into hemicellulose, lignin, and cellulose streams was used to produce furfural, phenolated lignin, and fermentable sugars in the acidic 1,4-dioxane system. Xylan was depolymerized to furfural at a yield of 93.81% of the theoretical value; however, the prolonged processing time (5 h) led to a high removal ratio of glucan (37.21%) in the absence of phenol. The optimum moderate condition (80 °C for 2 h with 2.5% phenol) was determined through the high fractionation efficiency. Consequently, 77.28% of xylan and 84.83% of lignin were removed and presented in the hydrolysate, while 91.08% of glucan was reserved in the solid portion. The formation of furfural from xylan remained high, with a yield of 92.92%. The extracted lignin was phenolated with an increasing content of phenolic hydroxyl. The fractionated lignin yield was 51.88%, which suggested this could be a low-cost raw material to product the activated carbon fiber precursor. The delignifi... [more]

During water and polymer flooding for enhanced oil recovery, pore structures may vary because of the fluid−rock interactions, which can lead to variations in petrophysical properties and affect oil field production. To investigate the effects of fluid flooding on pore structures, six samples were subjected to brine water, dual-system, and alkaline−surfactant−polymer (ASP) polymer displacement experiments. Before and after experiments, samples were scanned by X-ray CT. Thin sections, X-ray diffraction, and high pressure mercury injection tests were also carried out to characterize mineralogy and fractal dimension of pore systems before experiments. Experiment results show that water flooding with low injection pore volume ratio (IPVR) can improve reservoir quality since total porosity and connected porosity of samples rise after the flooding and the proportion of large pores also increases and heterogeneity of pore structure decreases. However, water flooding with high IPVR has reverse... [more]

The present study developed a new system of electrochemical water splitting using a boron doped diamond (BDD) electrode in the electrochemical reactor. The new method assessed the electrical current, acidity (pH), electrical conductivity, absorbance, dissipation, and splitting energies in addition to the water splitting efficiency of the overall process. Employing CuO NPs and ZnO NPs as catalysts induced a significant impact in reducing the dissipated energy and in increasing the efficiency of splitting water. Specifically, CuO NPs showed a significant enhancement in reducing the dissipated energy and in keeping the electrical current of the reaction stable. Meanwhile, the system catalyzed with ZnO NPs induced a similar impact as that for CuO NPs at a lower rate only. The energy dissipation rates in the system were found to be 48% and 65% by using CuO and ZnO NPs, respectively. However, the dissipation rate for the normalized system without catalysis (water buffer at pH = 6.5) is known... [more]

Airports, broadly spread world-wide, present continuously increasing energy demands for heating and cooling purposes. Relocatable facilities within them could be built on recycling shipping containers provided with the right insulation layer, to reduce the outstanding consumption of the heating, ventilation and air conditioning systems (HVAC). This research focuses on studying the effect of added insulation on the thermal performance of a construction in the scope of an airport facility, based on a recycled shipping container. Passive heating and cooling insulation strategies have shown good results in terms of energy savings. A series of simulations were performed along six different Spanish airports locations, selected to represent several climate conditions. Temperature evolution inside the container, and energy demands of the HVAC system were obtained to show that the insulation provided by phase change materials (PCM) is performing better than traditional insulation, or a raw cont... [more]

Kraft lignin (Indulin AT) pretreated with magnesium formate and magnesium hydroxide was fast-pyrolyzed in a continuously fed, bench-scale system. To avoid fouling issues typically associated with lignin pyrolysis, a simple laboratory test was used to determine suitable ranges of magnesium hydroxide and formic acid to lignin for feeding without plugging problems. Various feedstock formulations of lignin pretreated with magnesium hydroxide and formic acid were pyrolyzed. For comparison, calcium formate pretreated lignin was also tested. The organic oil yield ranged from 9% to 17% wt % on a lignin basis. Carbon yields in the oil ranged from 10% to 18% wt % on a lignin basis. Magnesium formate pretreatment increased oil yield and carbon yield in the oil up to 35% relative to the higher 1:1 g magnesium hydroxide/g lignin pretreatment. However, a lower magnesium hydroxide pretreatment (0.5:1 g magnesium hydroxide/g lignin) resulted in oil yields and carbon yields in the oils similar to the m... [more]

Cobalt oxide nanopowders are synthesized by the pyrolysis of aerosol particles of water solution of cobalt acetate. Cobalt nanopowder is obtained by subsequent reduction of obtained cobalt oxide by annealing under a hydrogen atmosphere. The average crystallite size of the synthesized porous particles ranged from 7 to 30 nm, depending on the synthesis temperature. The electrochemical characteristics of electrodes based on synthesized cobalt oxide and reduced cobalt oxide are investigated in an electrochemical cell using a 3.5 M KOH solution as the electrolyte. The results of electrochemical measurements show that the electrode based on reduced cobalt oxide (Re-Co3O4) exhibits significantly higher capacity, and lower Faradaic charge−transfer and ion diffusion resistances when compared to the electrodes based on the initial cobalt oxide Co3O4. This observed effect is mainly due to a wide range of reversible redox transitions such as Co(II) ↔ Co(III) and Co(III) ↔ Co(IV) associated with di... [more]

Recently, selective emitter (SE) technology has attracted renewed attention in the Si solar cell industry to achieve an improved conversion efficiency of passivated-emitter rear-contact (PERC) cells. In this study, we presented a novel technique for the SE formation by controlling the surface morphology of Si wafers. SEs were formed simultaneously, that is, in a single step for the doping process on different surface morphologies, nano/micro-surfaces, which were formed during the texturing processes; in the same doping process, the nano- and micro-structured areas showed different sheet resistances. In addition, the difference in sheet resistance between the heavily doped and shallow emitters could be controlled from almost 0 to 60 Ω/sq by changing the doping process conditions, pre-deposition and driving time, and temperature. Regarding cell fabrication, wafers simultaneously doped in the same tube were used. The sheet resistance of the homogeneously doped-on standard micro-pyramid su... [more]

Passive direct methanol fuel cells (pDMFCs) are promising devices to replace the conventional batteries in portable electronic devices, due to their higher energy densities, autonomies, and instant recharging. However, some challenges, such as their costs, efficiency, and durability, need to be overcome before their commercialization. Towards that, this work presents the effect of the anode diffusion layer (ADL) properties on the performance of a pDMFC using a membrane electrode assembly (MEA) with reduced loadings on both anode and cathode catalysts (3 mg/cm2 Pt/Ru on the anode and 1.3 mg/cm2 of Pt on the cathode). The pDMFC behavior was evaluated through polarization and electrochemical impedance spectroscopy measurements, which allow identifying and quantifying the different losses that affect these systems. The results showed better performances when a diffusion layer with a dual-layer structure was used using higher methanol concentrations. The maximum power density achieved was 3... [more]

In this work, the properties of silver-modified LiMn2O4 cathode materials are revisited. We study the influence of calcination atmosphere on the properties of the Ag-coated LiMn2O4 (Ag/LMO) and highlight the silver oxidation. The effect of the heat treatment in vacuum is compared with that in air by the characterization of the structure, specific surface area, Li transport properties and electrochemical performance of Ag/LMO composites. Surface analyses (XPS and Raman spectroscopy) show that the nature of the coating (~3 wt.%) differs with the calcination atmosphere: Ag/LMO(v) calcined in vacuum displays Ag nanospheres and minor AgO content on its surface (specific surface area of 4.1 m2 g−1), while Ag/LMO(a) treated in air is mainly covered by the AgO insulating phase (specific surface area of 0.6 m2 g−1). Electrochemical experiments emphasize that ~3 wt.% Ag coating is effective to minimize the drawbacks of the spinel LiMn2O4 (Mn dissolution, cycling instability, etc.). The Ag/LMO(v)... [more]

The dielectric strength and gel time of epoxy composites vary with the mixing ratio of epoxy resin, hardener, additives, filler, etc., and especially the gel time affects the productivity and economics of ultra-high-voltage (UHV) equipment. However, previous studies focused only on the dielectric strength of epoxy composites for the reliability of UHV equipment. Therefore, a study considering both the dielectric strength and gel time of the epoxy composite is required. In this paper, the characteristics of the gel time and dielectric strength of the epoxy micro-composites according to the mixing ratio of silica (SiO2) and alumina (Al2O3) micro-fillers without changing the mixing ratio of epoxy resin and hardener are analyzed. Experimental results show that the gel time decreased and the dielectric strength increased as the mixing ratio of the SiO2 micro-filler increased. Therefore, it is concluded that the gel time can be controlled by changing the mixing ratio of micro-fillers without... [more]

In this work, a three-dimensional microstructure-scale model of a Solid Oxide Fuel Cell’s Positive-Electrolyte-Negative assembly is applied for the purpose of investigating the impact of decreasing the electrolyte thickness on the magnitude, and the composition of electrochemical losses generated within the cell. Focused-Ion-Beam Scanning Electron Microscopy reconstructions are used to construct a computational domain, in which charge transport equations are solved. Butler−Volmer model is used to compute local reaction rates, and empirical relationships are used to obtain local conductivities. The results point towards three-dimensional nature of transport phenomena in thin electrolytes, and electrode-electrolyte interfaces.

Existing regulations on the thermal efficiency of building envelope assemblies are based on the steady state thermal properties of substrate materials. Heat transfer mechanisms of passive heat curbing methods such as phase change materials and cool materials, which are dynamic in nature, are currently not being accounted for. The effectiveness of thermo-physical and solar radiation properties of building materials (i.e., solid homogeneous layers without air gap) in reducing the heat gain into a building in a hot climate could be well understood with the equivalent thermal resistance (Req) concept. A simple and easy-to-use mathematical derivation (i.e., to estimate the instantaneous heat flux across an envelope assembly) is proposed in this paper to understand the mechanism of equivalent R-value (i.e., reciprocal of thermal transmittance, U-value) due to solar radiation properties of passive substrate materials. The model is validated against field experiments carried out at two apartme... [more]

The simple incineration of wood-based panels (WBPs) waste generates a significant amount of NO, which has led to urgency in developing a new method for treating the N-containing biomass residues. This work aims to examine the N evolution and physiochemical structural changes during the co-pyrolysis of fiberboard and glucose, where the percentage of glucose in the feedstock was varied from 0% to 70%. It was found that N retention in chars was monotonically increased with increasing use of glucose, achieving ~60% N fixation when the glucose accounted for 70% in the mixture. Pyrrole-N (N-5) and Pyridine-N (N-6) were preferentially formed at high ratios of glucose to fiberboard. While the relevant importance of volatile−char interactions to N retention and transformation could be observed, the volatile−volatile reactions from the two feedstocks played a vital role in the increase in abundance of glucose. With the introduction of glucose, the porous structure and porosity in chars from the... [more]

The friction of the orbiting scroll leads to large power consumption and low energy efficiency of the scroll compressor. The common methods to solve this problem are high cost and a complex process. Considering special structures and operating principles to apply the coating technology on the scroll compressor is a new subject. Given the material of the orbiting scroll being aluminum alloy, the unbalanced magnetron sputtering technology for the orbiting scroll of the scroll compressor was chosen and the Cr transition layer was coated to enhance the bonding strength. Moreover, we innovatively performed an experiment to verify the feasibility of unbalanced magnetron sputtering film coating technology for the diamond-like carbon film coated in the scroll compressor. This article elaborates the parameter test methods of the film properties before and after experiments and the experimental system components. The results showed that the diamond-like carbon film has low coefficient and high b... [more]

The manner of storage of sugar beets largely influences their physical and chemical properties, which may subsequently determine their biochemical methane potential. In this study, samples of fresh sugar beets as well as beets stored in two ways—in airtight conditions and in an open-air container—were tested. In both cases, measurements were taken on specific dates, i.e., after 4, 8, 16 and 32 weeks of storage. A decrease in pH was observed in all samples, with the lowest decrease occurring in hermetically stored samples. The lowest pH value of 3.71 was obtained for sugar beets stored in an open-air container after 32 weeks of storage. During storage, a gradual decrease in total solids was also recorded along with accompanying losses of organic matter, more significant in the case of storage in an open-air container. In subsequent storage periods, the biogas/methane production efficiency differed slightly for both methods. The highest volume of biogas was obtained for fresh sugar beets... [more]

The increased focus on global climate change has meant that the thermoelectric market has received considerably more attention. There are many processes producing large amounts of waste heat that can be utilised to generate electrical energy. Thermoelectric devices have long suffered with low efficiencies, but this can be addressed in principle by improving the performance of the thermoelectric materials these devices are manufactured with. This paper investigates the thermoelectric performance of market standard thermoelectric materials before analysing how this performance can be improved through the adoption of various nanotechnology techniques. This analysis is carried out through the computational simulation of the materials over low-, mid- and high-temperature ranges. In the low-temperature range, through the use of nanopores and full frequency phonon scattering, Mg0.97Zn0.03Ag0.9Sb0.95 performed best with a ZT value of 1.45 at 433 K. Across the mid-temperature range a potentiall... [more]

Since its invention in 2009, Perovskite solar cells (PSCs) has attracted great attention because of its low cost, numerous options of efficiency enhancement, ease of manufacturing and high-performance. Within a short span of time, the PSC has already outperformed thin-film and multicrystalline silicon solar cells. A current certified efficiency of 25.2% demonstrates that it has the potential to replace its forerunner generations. However, to commercialize PSCs, some problems need to be addressed. The toxic nature of lead which is the major component of light absorbing layer, and inherited stability issues of fabricated devices are the major hurdles in the industrialization of this technology. Therefore, new researching areas focus on the lead-free metal halide perovskites with analogous optical and photovoltaic performances. Tin being nontoxic and as one of group IV(A) elements, is considered as the most suitable alternate for lead because of their similarities in chemical properties.... [more]

In this work, the experimental investigations were piloted to study the influence of hybrid nanoparticles containing SiO2 and CeO2 nanoparticles on thermo-physical characteristics of the paraffin-based phase change material (PCM). Initially, the hybrid nanoparticles were prepared by blending equal mass of SiO2 and CeO2 nanoparticles. The hybrid-nano/paraffin (HnP) samples were prepared by cautiously dispersing 0, 0.5, 1.0, and 2.0 percentage mass of hybrid nanoparticles inside the paraffin, respectively. The synthesized samples were examined under different instruments such as field emission scanning electron microscope (FESEM), Fourier transform infrared spectrometer (FTIR), differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), and thermal properties analyzer to ascertain the influence of hybrid nanoparticles on thermo-physical characteristics of the prepared samples. The obtained experimental results proved that the hybrid nanoparticles were uniformly diffused in... [more]

1-Butanol can be considered as a good fuel additive, which can be used at high pressures. Therefore, the knowledge of high-pressure thermophysical properties is crucial for this application. In this paper, new experimental data on the speed of sound in 1-butanol in the temperature range from 293 to 318 K and at pressures up to 101 MPa are reported. The speed of sound at a frequency of 2 MHz was measured at atmospheric and high pressures using two measuring sets operating on the principle of the pulse−echo−overlap method. The measurement uncertainties were estimated to be better than ±0.5 m·s−1 and ± 1 m·s−1 at atmospheric and high pressures, respectively. Additionally, the density was measured under atmospheric pressure in the temperature range from 293 to 318 K using a vibrating tube densimeter Anton Paar DMA 5000. Using the experimental results, the density and isobaric and isochoric heat capacities, isentropic and isothermal compressibilities, isobaric thermal expansion, and interna... [more]

Despite the multiple advantages of prefabricated compared to conventional buildings, such as significant reductions in cost and time, improved quality and accuracy in manufacture, easy dismantling and reuse of components, reduction in environmental degradation, increase of productivity gains, etc., they still share a small part of the European building stock, mainly in the Mediterranean. This paper attempts to highlight the potential of prefabricated buildings to achieve advanced levels of performance, particularly as regards their thermal and energy behavior. More specifically, in this paper the energy needs of a single-family building constructed with prefabricated elements is analyzed, considering different climate contexts. The prefabricated elements comprising the building envelope were developed in order to address specific requirements with respect to their structural, hygrothermal, energy, fire, acoustical, and environmental performance, within the research project SUPRIM (sust... [more]

Efficient use of solar energy by thermal energy storage composites and utilizing environmentally friendly cementitious materials are important trends for sustainable building composite materials. In this study, a paraffin/low density polyethylene (LDPE) composite shape-stabilized phase change material (SSPCM) was prepared and incorporated into a sulphoaluminate cement (SAC) mortar to prepare thermal energy storage mortar. The thermal and mechanical properties of SSPCM and a SAC-based thermal energy storage material (SCTESM) were investigated. The result of differential scanning calorimeter (DSC) analysis indicates that the latent heat of SCTESM is as high as 99.99 J/g. Thermogravimetric analysis demonstrates that the SCTESM does not show significant decomposition below 145 °C. The volume stability test shows the volume shrinkage percentage of the SCTESM is less than that of pure SAC mortar and far less than that of ordinary Portland cement mortar. The SCTESM has high early strength so... [more]

The aim of this study was to analyze the effect of ZnO nanoparticles (ZnO NPs) on the biogas production from mechanically treated barley straw and to perform a techno-economic analysis based on the costs assessment and on the results of biogas production. The structural changes of mechanically pretreated barley straw were observed using FTIR, XRD, TGA, and SEM. Additionally, both green ZnO NPs prepared from red alga (Antithamnion plumula) extract and chemically prepared ZnO NPs were characterized by FTIR, XRD, SEM, and TEM, surface area, and EDX. The results revealed that the biogas production was slightly improved by 14.9 and 13.2% when the barley straw of 0.4 mm was mechanically pretreated with 10 mg/L of both green and chemical ZnO NPs and produced 390.5 mL biogas/g VS and 385 mL biogas/g VS, respectively. On the other hand, the higher concentrations of ZnO NPs equal to 20 mg/L had an inhibitory effect on biogas production and decreased the biogas yield to 173 mL biogas/g VS, which... [more]

Designing carbonaceous materials with heightened attention to the structural properties such as porosity, and to the functionalization of the surface, is a growing topic in the lithium-ion batteries (LIBs) field. Using a mesoporous silica KIT-6 hard template, mesoporous carbons belonging to the OMCs (ordered mesoporous carbons) family, namely 3D cubic CMK-8 and N-CMK-8 were synthesized and thoroughly structurally characterized. XPS analysis confirmed the successful introduction of nitrogen, highlighting the nature of the different nitrogen atoms incorporated in the structure. The work aims at evaluating the electrochemical performance of N-doped ordered mesoporous carbons as an anode in LIBs, underlining the effect of the nitrogen functionalization. The N-CMK-8 electrode reveals higher reversible capacity, better cycling stability, and rate capability, as compared to the CMK-8 electrode. Coupling the 3D channel network with the functional N-doping increased the reversible capacity to ~... [more]

In recent years, with developing technology in the field of electrical machines, more efficient and high power density electric motors have been produced. The use of high energy efficiency motors gains importance due to the increase in global energy demand. The main purpose of this study was to design an Axial Flux Induction Motor (AFIM) with the same efficiency class as the Radial Flux Induction Motor (RFIM) in premium efficiency (IE3) class which is used commonly in industrial applications. Various AFIMs are designed with different rotor slot numbers and performance analyses as efficiency and torque ripple changes are investigated. It is known that torque ripple is one of the key parameters in electrical machine design which should be kept as low as possible without decreasing efficiency and torque. Accordingly, AFIMs’ rotor slots are skewed considering the stator and rotor slot numbers. The use of a Soft Magnetic Composites (SMC) material in design is also investigated. As a result... [more]

The effect of different supports such as silica (SBA-15), activated carbon (AC), and mesoporous alumina (Al2O3) on catalytic activities of hydrotreating nickel molybdenum (NiMo) catalysts was demonstrated for upgrading vacuum residue. Nitrogen adsorption-desorption analysis showed that SBA-15 and the AC-supported NiMo catalyst possessed a very high surface area compared to the alumina-supported catalyst. However, NiMo/Al2O3 catalyst possesses a higher pore diameter and pore volume with an appropriate surface area. X-ray diffraction (XRD) analysis showed that active metals were dispersed in the catalytic supports. Transmission electron microscopy (TEM) analysis revealed the presence of type II active MoS2 sites in the NiMo/Al2O3 catalyst, which showed weak metal-support interactions having a high intrinsic activity. Catalyst activities such as hydrodesulfurization (HDS), hydrodemetallization (HDM) and asphaltene conversion (HDAs), and hydrocracking conversions of a vacuum residue were e... [more]