Decrease In Hc Research Articles

Anisotropic SmFe10V2 Bulk Magnets with Enhanced Coercivity via Ball Milling Process.

Anisotropic bulk magnets of ThMn12-type SmFe10V2 with a high coercivity (Hc) were successfully fabricated. Powders with varying particle sizes were prepared using the ball milling process, where the particle size was controlled with milling time. A decrease in Hc occurred in the heat-treated bulk pressed from large-sized powders, while heavy oxidation excessively occurred in small powders, leading to the decomposition of the SmFe10V2 (1-12) phase. The highest Hc of 8.9 kOe was achieved with powders ball-milled for 5 h due to the formation of the grain boundary phase. To improve the maximum energy product ((BH)max), which is only 2.15 MGOe in the isotropic bulk, anisotropic bulks were prepared using the same powders. The easy alignment direction, confirmed by XRD and EBSD measurements, was <002>. Significant enhancements were observed, with saturation magnetization (Ms) increasing from 59 to 79 emu/g and a remanence ratio (Mr/Ms) of 83.7%. (BH)max reaching 7.85 MGOe. For further improvement of magnetic properties, controlling oxidation is essential to form a uniform grain boundary phase and achieve perfect alignment with small grain size.

A comprehensive combustion, performance, and environmental analyses of algae biofuel, hydrogen gas, and nano-sized particles (liquid-gas-solid mix) in agricultural CRDI engines

The present research encompasses the utilization of TiO2 nano particles with enrichment of H2 (10 lpm) with Chlorella Emersonii Methyl Ester (CEME) on an agricultural-based CRDI engine. CEME20 (20% chlorella emersonii methyl ester blended with 80% mineral diesel) is employed for the tests. The nanoparticle concentration is limited to 50 ppm which has been considered according to O2 concentration in biodiesel. Experimentation revealed that, with hydrogen gas and TiO2 nanoparticles, the BTE and BSFC were improved significantly. At full load conditions, BTE is enlarged by 7.3%. In addition, there is a simultaneous decrease in HC and CO emissions (by about 36.3 and 40.9% respectively) for algal biofuel blends, while NOx emissions increased by 27.3% with respect to mineral diesel. 5.1% and 6.5% increase in combustion characteristics (79.8 bar combustion pressure and 89.2 J/°CA heat release rate)were observed for the CEME/H2/TiO2 blend which could be attributed to effective combustion of hydrogen and catalytic combustion activity provided by TiO2 nano additives. CEME/H2/TiO2blend recorded maximum Mass Fraction burnt (MFB) (74.7%) as well as lowered PSD (Particle size Diameter) profile (34.8 nm @ 0.29 E+08 dN/dlogDp (#/cm3)) at full engine load condition indicating the presence of H2 and nano additives which has influence over the combustion.

Magnetic Barium Hexaferrite Nanoparticles with Tunable Coercivity as Potential Magnetic Heating Agents.

Using magnetic nanoparticles (MNPs) for extracorporeal heating applications results in higher field strength and, therefore, particles of higher coercivity can be used, compared to intracorporeal applications. In this study, we report the synthesis and characterization of barium hexa-ferrite (BaFe12O19) nanoparticles as potential particles for magnetic heating. Using a precipitation method followed by high-temperature calcination, we first studied the influence of varied synthesis parameters on the particles' properties. Second, the iron-to-barium ratio (Fe/Ba = r) was varied between 2 and 12. Vibrating sample magnetometry, scanning electron microscopy and X-ray diffraction were used for characterization. A considerable influence of the calcination temperature (Tcal) was found on the resulting magnetic properties, with a decrease in coercivity (HC) from values above 370 kA/m for Tcal = 800-1000 °C to HC = 45-70 kA/m for Tcal = 1200 °C. We attribute this drop in HC mainly to the formation of entirely multi-domain particles at high Tcal. For the varying Fe/Ba ratios, increasing amounts of BaFe2O4 as an additional phase were detected by XRD in the small r (barium surplus) samples, lowering the particles' magnetization. A decrease in HC was found in the increased r samples. Crystal size ranged from 47 nm to 240 nm and large agglomerates were seen in SEM images. The reported particles, due to their controllable coercivity, can be a candidate for extracorporeal heating applications in the biomedical or biotechnological field.

Comparative assessment of emissions, performance, and economics parameters for a dual–fuel diesel generator operating with rice bran biodiesel and hydrogen

The first step to achieving an energy transition is partially substituting fossil fuels with other more environmentally friendly alternatives, such as hydrogen gas. The current research aims to evaluate the influence of hydrogen in a diesel generator fueled with rice bran biodiesel. The above encourages the use of hydrogen and biodiesel production from residual raw material. For the development of the research, a diesel engine bench was used, which operated in five load conditions: 20 %, 40 %, 60 %, 80 %, and 100 %, and was fed with three fuels: −100 %, RB-10 %, and RB-10 % + H2(30 %). The results show that the mixture RB-10 % + H2(30 %) causes a 3.14 % reduction in BSFC and a 3.26 % increase in energy conversion efficiency. In addition, it is observed that a 9.90 %, 12.57 %, and 10.99 % decrease in HC, CO, and smoke opacity emissions compared to pure diesel. On the other hand, the mixture RB-10 % + H2(30 %) reduces by 4.44 %, 5.07 %, and 7.06 % the environmental, social, and ecological impact due to CO2, HC, and CO emissions, as well as a 3.93 % reduction in engine operating cost compared to RB-10 % biodiesel. In general, hydrogen injection is a promising alternative to promote the use of rice bran biodiesel due to its increased performance characteristics and reduced pollutant emissions without the need to modify the engine.

Laser powder bed fusion of NdFeB and influence of powder bed heating on density and magnetic properties

Laser powder bed fusion (L-PBF) is an additive manufacturing technique that provides an opportunity to create complex NdFeB magnets, potentially enhancing their performance. L-PBF possesses its own processing challenges, such as porosity/cracks and thermal stresses due to rapid cooling. This study focused on optimizing the parameters and the use of elevated temperature (300–550 °C) powder bed heating to reduce defect generation. This paper includes a detailed process parameter investigation, which revealed samples with a maximum energy product, (BH)max, of 81 kJ/m3 (remanence, Br 0.72 T; coercivity, Hci 891 kA/m) without post/pretreatment, which are the highest (BH)max and Br for L-PBF-processed NdFeB commercial powder. It was observed that all the high-magnetism samples possessed high density, but not all the high-density samples possessed high magnetism. The SEM images and discussions are academically valuable since they clearly illustrate grain formation and morphology in the melt pool, areas where the literature provides limited discussion. Furthermore, this paper incorporates quantitative phase analyses, revealing that the magnetic properties increase with increasing volume fraction of the strong magnetic phase Nd2Fe14B. Another significant contribution of this paper is that it is the first study to investigate the effect of heated bed on L-PBF-NdFeB alloys. The density of the samples and Br can be improved with the use of elevated powder bed heating, while the Hc decreases. The (BH)max can also be improved from 55 to 84 kJ/m3 through elevated powder bed heating. The maximum magnetic properties obtained with the heated bed (400 °C) were as follows: Br, 0.76 T; Hci, 750 kA/m; and (BH)max, 84 kJ/m3.

Drastic enhancement of stable and fast domain wall motion in GdFe nanowires through laser-annealing treatment at wire edges

One of the key challenges in racetrack memory (RM) technology is achieving stable and high velocities for domain walls (DWs) while maintaining low power consumption. In our study, we propose a novel laser-annealing (LA) process to modify wire edges for a smoother DW movement along the nanowire. In this regard, a film stack of Pt (5 nm)/Gd26Fe74(20 nm)/SiN(10 nm) was deposited by magnetron sputtering. The DW velocity in the wire was measured by applying single voltage pulses and then observing the DW motion using a Kerr microscope. The current-induced domain walls motion measurements have shown that the LA process significantly enhances the velocity of DW motion. The LA of both edges of the nanowire results in a threefold increase in DW velocity compared to non-LA conditions. Further experiments illustrated that the DW velocity remains stable for the laser-annealed condition across a wide range of applied currents, spanning from 3 × 1011 to 7 × 1011 A/m2. Additionally, our investigation into the magnetic characteristics of laser-annealed nanowire regions exhibited a notable reduction of Hc at the laser-annealed edges. This decrease in Hc indicates greater ease in manipulating the material’s magnetization, which is essential for efficient DW motion. Furthermore, we explored the influence of LA on the Dzyaloshinskii–Moriya Interaction (DMI) field. The DMI finding underscores the strong correlation between DMI fields and DW speed. This achievement, i.e. the stability and consistency of the domain’s velocity (as the components of an RM) in a wide range of applied current, is significant progress in the field of operation and industrialization of RM.

Investigation of effects on fuel consumption and exhaust emissions by using bioethanol gasoline mixture in an engine with ultrasonic fuel system

This study compared the fuel consumption and exhaust emissions of a spark-ignition engine using a carburetor fuel system, an injection fuel system, and an ultrasonic fuel system. When using gasoline only, the ultrasonic fuel system showed a 31% decrease in fuel consumption compared to the carburetor system and a 15% decrease compared to the injection system. When adding 10% bioethanol to the gasoline, fuel consumption increased in all three systems, with the ultrasonic system showing the largest increase of 10%. Exhaust emissions were also measured, and the ultrasonic system showed a significant decrease in CO, HC, and NOx compared to the carburetor and injection systems, with the largest decrease in CO emissions. The addition of bioethanol to the fuel resulted in reducing exhaust emission values in all three systems, with the ultrasonic system showing the largest decrease in CO and HC emissions compared to the carburetor and injection systems, but with an increase in NOx emissions compared to the injection system. When comparing three fuel systems, it was observed that injection fuel systems have the highest CO2 values. Although the addition of alcohol to the fuel does not cause a significant change in CO2 emission values for injection and ultrasonic fuel systems, an increase is observed in the carburetor fuel system. Overall, the ultrasonic fuel system showed promising results for reducing fuel consumption and improving exhaust emissions.

Effect of Mo in-situ alloying on microstructure and magnetic properties of (NiFeMo)100−xMox alloy

This study aimed to modulate the magnetic properties of selective laser melting NiFeMo alloy. This was achieved via the controlled addition of Mo elemental in-situ alloying content to change the tissue morphology and crystal structure of SLM-formed (NiFeMo)100−xMox alloy (x = 0 wt%, 0.25 wt%, 0.5 wt%, 0.75 wt%, 1.0 wt%, 1.25 wt%, 1.5 wt%, 2.0 wt%). The results of scanning electron microscopy (SEM), X-ray diffraction, electron backscatter diffraction (EBSD), DC B-H hysteresis tester, and transmission electron microscopy (Titan-G2) indicate that all samples are predominantly face-centered-cubic (FCC) γ- (Ni, Fe) solid solutions and typical soft-magnetic hysteresis line features. However, the lattice parameter a of γ- (Ni, Fe) decreased and then increased with increasing Mo content. When the added Mo content is 0–1.25 wt%, the Mo particles inside the (NiFeMo)100−xMox alloy become nucleation sites, creating a diffusive metallurgical behavior with the Ni and Fe elements, and preventing the growth of columnar crystals, leading to the reduction of LAGBs density and the enhancement of the {111} texture orientation in the easy magnetization direction, increasing Bs and the decrease of Hc of the NiFeMo alloy. At the Mo content of 1.25 wt%, the soft magnetic properties were optimal, with Bs and Hc being 0.704 T and 17.31 A/m, respectively. Conversely, when the added Mo content was 1.5–2.0 wt%, the solubility of Mo elements in the γ- (Ni, Fe) solid solution was limited, which resulted in the occurrence of metallurgical defects within the organization such as unfused Mo particles, unfused areas, and porosity. Moreover, when the added Mo content increased to 2.0 wt%, the {111} lattice spacing in the easy magnetization direction increased by 0.2261 nm compared to the NiFeMo alloy, and the average lattice distortion Δε increased to 0.16%, causing a decrease in the soft magnetic performance of the (NiFeMo)98Mo2 alloy, with Bs reducing to 0.6666 T and Hc increasing to 23.44 A/m.

Synergetic effect of hydrogen supplementation with waste cooking oil biodiesel – An assessment of the emission, combustion and performance parameters of a compression ignition engine

This investigation aims at examine the effects of hydrogen gas at different flow rates in combination with biodiesel made from used cooking oil on the combustion, emissions, and performance parameters of an engine. In order to improve the thermal performance and combustion characteristics of the stationary engine and lower its emissions, hydrogen is injected through the main manifold at varying flow rates ranging from 3 to 9 LPM, and waste cooking oil biodiesel (WCO B20) is injected through the injector as the main fuel. Both of these fuels are used in conjunction with each other. Results of combustion characteristics revealed that the cylinder pressure enhanced by about 7.32 % using 9 LPM hydrogen flow through the main manifold compared to diesel fuel. Similarly, the HRR from the engine using 9 LPM hydrogen flow enhanced by about 9.43 and 13.76 % compared to diesel and WCO B20, respectively. A comparison is made between diesel fuel and with the proposed modified fuel on the engine's performance, which is assessed in terms of BTE and BSFC. For a range of different engine loads, several emission parameters including HC, NOx, CO, CO2, and smoke opacity are monitored and analyzed for the fuel that has been produced. The results showed that the BTE of the engine is higher in the case of WCO B20 with hydrogen fuel in the flow rate of 9 LPM by about 35.38 % at various engine loads in comparison with the other flow rates of hydrogen fuel, WCO B20 blend, and diesel fuel. Similarly, there is a significant decrease in the SFC by about 17.85 % of the fuel using hydrogen fuel at higher flow rates. The CO emissions with WCO B20 biodiesel blend and diesel fuel are higher, whereas there is a substantial reduction in the CO emission about 22.58 % using a higher concentration of hydrogen fuel along with the WCO B20 biodiesel blends. Similarly, the other emissions such as CO2, smoke and HC decrease about 5.38 %, 10.41 % and 5.38 % whereas the NOx formation increases about 7.67 % at peak loads due to a higher rate of combustion.

Influence of hydrogen fraction and injection timing on in-cylinder combustion and emission characteristics of hydrogen-diesel dual-fuel engine

In order to achieve low-carbon, high-efficient and clean combustion for internal combustion engines, hydrogen-diesel dual-fuel combustion mode (HDDF) was conducted on a 4-cylinder common-rail diesel engine. This research investigated the effects of hydrogen substitution ratio (HSR) and diesel injection timing (DIT) on in-cylinder combustion and emission characteristics of HDDF engine at 20% and 40% loads. The results show that with the increase of HSR, the maximum combustion pressure of HDDF engine shows a decreasing trend, and the peak phase gradually advances. The overall trends of COVIMEP and combustion duration increase. The NO, CO2, CO, Soot and HC emissions all decrease, while NOx emissions first decrease and then increase. At 20% load and HSR = 30% conditions, CO2 emission decreases by 14.96% compared to baseline engine. With the advance of DIT, the maximum combustion pressure of HDDF engine increases, the ignition delay and combustion duration become longer, and COVIMEP shows a downward trend. The NO2, NO, CO2 and NOx emissions and BTE increase, while both CO and HC decrease. When the DIT is advanced from −2 °CA ATDC to −10 °CA ATDC, the BTE of HDDF engine increases from 28.8% to 31.3%.

Performance Improvement and Emission Reduction Potential of Blends of Hydrotreated Used Cooking Oil, Biodiesel and Diesel in a Compression Ignition Engine

The positive effect of decarbonizing the transport sector by using bio-based fuels is high. Currently, biodiesel and ethanol are the two biofuels that are blended with fossil fuels. Another technology, namely, hydroprocessing, is also gaining momentum for producing biofuels. Hydrotreated vegetable oil (HVO) produced using this process is a potential drop-in fuel due to its improved physiochemical properties. This study aimed to reduce the fossil diesel content by blending 20% and 30% HVO and 5%, 10% and 15% waste cooking oil biodiesel on a volume basis. The blends were used to conduct a thorough performance examination of a single-cylinder compression ignition engine. The thermal efficiency of the engine was enhanced by the addition of biodiesel to the blend. The efficiency increased as the proportion of biodiesel in the mix increased, although it was still less efficient than diesel. The maximum improvement in thermal efficiency of 4.35% was observed with 20% blending of HVO and 15% blending of biodiesel compared with 20% blending of HVO and diesel. However, the HC (decrease of 30%), CO (decrease of 23.5%) and smoke (decrease of 21.1%) emissions were observed to be the lowest with 30% blending of HVO and 15% blending of biodiesel. A fuzzy-logic-based Taguchi method and Grey’s method were then applied to find the best blend of HVO, biodiesel and diesel. The combination of the two methods made it easier to carry out multi-objective optimization. The brake thermal efficiency (BTE), smoke and NO emissions were selected as the output parameters to optimize the HVO and biodiesel blend. The optimization study showed that 30% blending of HVO and 15% blending of biodiesel was the best blend, which was authenticated using the confirmation experiment.

Investigation of the effects of Cu layer thickness and annealing temperature under air atmosphere on the properties of Co/Cu multilayer films

In this study, the suitability of Co/Cu multilayer films with different physical conditions (varying thickness values and systematic annealing processes) in magnetic technology applications is discussed. Co/Cu films were deposited by the sputtering technique. The effects of different thicknesses of non-magnetic (Cu) layers and annealing temperature on magneto-structural properties were investigated. Different thicknesses of Cu layers were determined as 34 nm, 10 nm, 4 nm. Additionally, two annealed situations were considered to investigate the annealing effect. While the first one is exposing the films to 80 °C and 130 °C for 240 s, second one is annealing the films at 180 °C for different exposure times (50 s and 150 s). All films that have different thicknesses of Cu layers crystallized in (111) plane of the face centered cubic (fcc) structure. The intensity of this peak increased with increasing Cu layers thickness. Variation in the thickness of Cu layers has an important effect on the film surface. Saturation magnetization (Ms), coercivity (Hc) and squareness (Mr/Ms, Mr: remanent magnetization) were considerably affected by variation of the Cu content and film surface caused by the change in the thickness of the Cu layers. The film with 4 nm Cu layer thickness has the highest Ms, lowest Hc values and high Mr/Ms ratio. This indicates magnetically high efficient compared to the other films in the same series. The fcc structure continued to exist for the films annealed at 80 °C and 130 °C for 240 s. It was found that the annealing procedure transfigured the film surface and the differences in Ms and Hc values can be mostly attributed to this transfiguration because of the same film content revealed. An increase in Ms value, and a slight decrease in Hc and Mr/Ms values were detected for the annealed film at 130 °C, compared to the film annealed at 80 °C. It was also seen that the film structure was damaged at 180 °C because of excessive heat transfer.

Experimental investigations on SI engine with piston coatings and gasoline blends

Internal combustion engine fuel use is rising, gas prices are fluctuating, we are using less fossil fuels and natural resources, and we need to develop alternative fuels with lower carbon contents. This study compares several gasoline mixtures in a single-cylinder, two-stroke SI engine. The current experimental work provides a thermal barrier for gasoline mixtures containing ethanol, butanol, and propanol by 100-µm piston crown coatings of magnesium partially stabilized zirconium (Mg-PSZ). 20% ethanol and 80% gasoline, 20% butane and 80% gasoline, and 20% propane and 80% gasoline made up the fuel mixture samples. The following engine variables must be assessed in this experiment for coated and uncoated pistons: brake-thermal efficiency (BTH), specific fuel consumption (SFC), and HC and CO emissions. According to the experiment findings, employing E20 resulted in a 4% gain in thermal efficiency, a 1.78% decrease in specific fuel consumption, and a 2.0% and 2.4% decrease in HC and CO exhaust emissions. The results show that heat barrier coatings and gasoline blends (E20) may improve engine performance while lowering exhaust emissions.

Equilibrium magnetic properties of the Fe-doped HTSC YBaCuO

For the polycrystalline high-temperature superconductor Y1 –xFexBa2Cu3Oy (0 ≤ x ≤ 0.05), where a significant increase in the intragrain critical current density has recently been found, the effect of iron doping on the equilibrium magnetic characteristics is studied. The field dependences of the magnetization are measured in the temperature range of 40–85 K and in the field range up to 60 kOe with increasing and decreasing fields. The temperature dependences of the London penetration depth λab, the superconducting carrier density ns, and the thermodynamic critical field Hc are determined from an analysis of the middle lines of the magnetic hysteresis loop. It is shown that the thermodynamic properties of Fe substituted samples do not change at x ≤ 0.03. At a higher Fe content, a slight decrease in Hc and the superconducting transition temperature is observed. However, changes in the condensation energy turn out to be much smaller than values expected due to an increase in the density of effective pinning centres created by substitutional atoms in both the yttrium and copper sublattices. It is concluded that the pinning regions in chain CuO planes near substituted Cu sites are two-dimensional in nature and do not affect the superconducting pairing in CuO2 planes. Another possible pinning mechanism, which does not affect Hc, is the interaction of vortices with the magnetic moments of Fe3+ ions.

Effect of surface wettability on specific heat capacity of nano-confined liquid

Equilibrium Molecular Dynamics (EMD) simulations are carried out to investigate the effects of wall wettability and nanogap thickness (h) on the constant volume molar heat capacity (Cv) of liquid argon entrapped between two solid copper walls at a fixed temperature of 100 K. Lennard-Jones (LJ) potential is employed to model the interaction between atoms, with nanogap thickness (h) varying between 0.585 nm to 5.85 nm. To characterize interfacial surface wettability as hydrophobic or hydrophilic, the solid-liquid interaction potential has been altered, and its effect on molar heat capacity (Cv) has been evaluated. Simulation results reveal three key findings. As the surface becomes more hydrophobic (i) both maximum heat capacity (Cv,max), and critical nanogap thickness (hc) (nanogap thickness at which maximum heat capacity is obtained) decrease; (ii) the range of nanogap thickness where the heat capacity of nanoconfined liquid surpasses that of bulk liquid diminishes; (iii) the heat capacity of nanoconfined liquid tends to match its bulk equivalent. This anomalous behavior of heat capacity with changing wall wettability is explained by variation in both vibrational (mode of phonon transportation) and configurational (density oscillation near the wall, thermal boundary resistance, molecular mobility, etc.) contribution of nanoconfined liquid.

The effect of metallic and nonmetallic oxide nanoparticles dispersed Mahua biodiesel on diesel engine performance and emission characteristics

The objective of this study is to evaluate the performance and emission characteristics of a diesel engine using metallic graphene oxide (GO) and nonmetallic zinc oxide (ZnO) nanoparticles in a Mahua biodiesel blend (B20). At a concentration of 75 mg/L, both GO and ZnO nanoparticles were considered and a surfactant (CTAB) and a dispersant (TWEEN 80) were added at a 1:1 ratio for surface modification. The nanofuel samples were analyzed for stability using a spectrophotometer. The nanoparticles mixed with dispersants and surfactants have shown improved stability. In addition, the injection pressure was varied from 200 to 250 bar. Dispersion of GO and ZnO nanoparticles in BD20 improved performance parameters such as BTE and BSFC. In addition, there was a significant decrease in CO, HC, smoke, and NOx emissions. TWEEN 80-added GO and ZnO nanoparticles in B20 achieved the best results, followed by the CTAB-added nanoparticles. In addition, the operating parameters showed a favorable trend toward improvement at higher injection pressures. At 250 bar, BTE was improved by 4.24% and BSFC was reduced by 3.59% compared to diesel. Also, the CO, UHC, NOx, and smoke opacity were reduced by 47.05%, 15.12%, 18.96%, and 37.09% for B20 + ZnO75 mg/L + TWEEN75 mg/L, respectively.

Elemental synergistic effect in CoxCrCuFeMnNi high-entropy alloys and its influence on phase and magnetic properties

CoxCrCuFeMnNi (x = 0, 0.5, 1.0, 1.5, 2.0 mol, named as Co0, Co0.5, Co1.0, Co1.5, and Co2.0, respectively) high-entropy alloys (HEAs) were prepared by powder metallurgy. The phase formation, elemental synergistic effect, and magnetic properties of HEAs were studied. The elemental synergistic effect on the magnetic properties was also discussed. Co0 alloy comprised the FCC1 main phase, FCC2 secondary phase, and minor ρ phase, whereas other alloys comprised the FCC2 main phase and FCC1 secondary phase. When Crequiv>1.22Coequiv+16.4 was satisfied, a BCC main phase + FCC secondary phase or BCC phase structure easily formed in the alloys. When Crequiv≤1.22Coequiv+16.4 was satisfied, an FCC main phase + BCC secondary phase or FCC phase structure easily formed. The saturation magnetization (Ms) and coercive force (Hc) of Co0 alloy were 0.8 emu/g and 9 Oe, respectively. With increased Co content, Ms increased and Hc changed irregularly. When the Co content reached 2.0 mol, Ms increased to 4.5 emu/g and Hc decreased to 7 Oe. The increase in Coequiv increased the Ms, but Crequiv had little influence on it. Only at 15%–20% Crequiv did Hc decrease with increased Coequiv. Conversely, in other cases, the alloy's Hc cannot be effectively reduced by adjusting Coequiv and Crequiv.

Effect of HHO addition on combustion and emission in SI engine with butanol direct injection and gasoline port injection

As a renewable biofuel fuel with similar properties to gasoline, butanol can not only reduce the consumption of fossil energy, but also effectively improve the performance of engine. However, when the mixture ratio of butanol is large, the combustion of the mixture will deteriorate due to the high latent heat of butanol vaporization. In order to solve this problem, the HHO supply system was innovatively built on the basis of butanol/gasoline compound injection system. The HHO produced by the HHO supply system is sucked into the cylinder by the way of negative pressure in the cylinder. This system also forms a new intake system with the original intake system. In this research, the engine speed is 1500 rpm, manifold absolute pressure (MAP) is 42 kPa, and λ is 1. Five butanol direct injection ratio (BDIr), five HHO flux and six direct injection timing (DIT) are studied to observe the combination effects of butanol and HHO. The results show that under all test conditions, with the increase of HHO flux, indicated mean effective pressure (IMEP), peak in-cylinder pressure (Pmax) and NO increase, CA 0–10, CA 10–90, CO and HC decrease. When HHO flux increases from 0 to 16 L/min, IMEP increases by 4.84% and CO emission decreases by 22.52%. It is worth noting that this improvement is more obvious when BDIr >40%. HHO can effectively offset the negative impact of large proportion of butanol vaporization latent heat and improve the engine's tolerance to BDIr. Moreover, the engine performance gap between different DIT is also shortened with the addition of HHO, which reduces the engine's sensitivity to DIT. In addition, it can also be found that butanol can improve the surge of NO emission caused by HHO. When BDIr ≥60%, the NO emission after the introduction of HHO can be maintained at the original level or even lower. In general, biofuel butanol and clean fuel HHO can work together well and “16 L/min HHO +40% BDIr +60% GPIr +300 ° CA BTDC DIT” is the optimal combination of the BDI + GPI + HHO engine.

Hydrothermal synthesis of FeCo alloys with excellent microwave Absorption: Effect of reaction time

The hydrothermal method was used to prepare FeCo alloys with varying reaction times. The results show that the reaction time has a significant impact on the microstructure and microwave absorption properties of FeCo alloys. By varying the reaction time (8 h, 10 h, and 12 h), the alloy phase becomes increasingly purer, and the particle size and saturation magnetization (MS) of the alloys increase, but the coercive force (Hc) decreases. At the same time, the morphology of FeCo alloys gradually changed from irregular small particles to hexagonal star-shaped large particles. When the reaction time is 10 h, the FeCo alloys shows the highest attenuation coefficient (α), excellent impedance matching performance, and microwave absorption performance. When the matching thickness is 1.95 mm, the minimum reflection loss (RLmin) value at 11.12 GHz is −49.88 dB. When the matching thickness is 1.56 mm, the maximum effective absorption bandwidth (EABmax) is 6.8 GHz (11.2–18 GHz).

Understanding the performance, emissions, and combustion behaviors of a DI diesel engine using alcohol/hemp seed oil biodiesel/diesel fuel ternary blends: Influence of long-chain alcohol type and concentration

In this study, it was aimed to examine the influences of biodiesel–diesel-higher alcohol (1-pentanol, 1-hexanol, and 1-heptanol) blends on the performance, emission and combustion behaviors of a single-cylinder diesel engine. The tests were performed at a fixed speed of 1500 rpm and variable loads (25%, 50%, 75%, and 100%). For the tests, 80% diesel and 20% hemp seed oil biodiesel were blended and called as B20. Biodiesel fuel was produced by transesterification from hemp seed oil in the presence of methanol and potassium hydroxide for the preparation of B20 binary test fuel and other ternary fuels. Furthermore, nine ternary blend fuels [20% HSOB + 70%, 60% and 50% diesel, respectively + 10%, 20% and 30% higher alcohol (pentanol, hexanol and heptanol) respectively] were prepared. The calculations made with the experimental data revealed that the minimum brake specific energy consumption values were 12,48 MJ/kW h, 13,06 MJ/kW h, 13,27 MJ/kW h, 13,35 MJ/kW h, 13,47 MJ/kW h, and 13,59 MJ/kW h, respectively, for diesel fuel at full load, for fuels B20, B20Hx10, B20Hp10, B20Hx20 and B20Pe10, the maximum brake thermal efficiency values were obtained as 28.85%, 27.56%, 27.14%, 26.97%, 26.73% and 26.49%, respectively, for the same fuels at the same load. The increment in higher alcohol concentration in the blend delayed start of combustion and therefore the ignition delay period was prolonged. In the fuel line pressure data, changes were observed depending on the amount, viscosity and density of the fuel. Furthermore, B20Hx10 and B20Hp10 fuels gave the maximum in-cylinder pressure, heat release rate, average gas temperature and pressure rise rate values after diesel and biodiesel. The addition of biodiesel and higher alcohol to diesel fuel resulted in a decrease in NOX, CO and unburned HC and smoke emissions and an increase in CO2. NOX, CO and unburned HC values of higher alcohol blended fuels at full load showed lower results, between 3.04–22.24%, 22.85–56.35% and 5.44–22.83%, respectively, compared to diesel fuel. It can be concluded that the use of hemp seed oil biodiesel and higher alcohol in the diesel engine will make a significant contribution to the reduction of NOX emissions.