Rev Min Research Articles

Combustion, performance and emissions of ULSD, PME and B50 fueled multi-cylinder diesel engine with naturally aspirated hydrogen

An experimental study was conducted on a diesel engine fueled with ultra-low sulfur diesel (ULSD), palm methyl ester (PME), a blended fuel containing 50% by volume each of the ULSD and PME, and naturally aspirated hydrogen, at an engine speed of 1800 rev min−1 under five loads. Hydrogen was added to provide 10% and 20% of the total fuel energy. The following results are obtained with hydrogen addition. There is little change in peak in-cylinder pressure and peak heat release rate. The influence on fuel consumption and brake thermal efficiency is engine load and fuel dependent; being negative for the three liquid fuels at low engine loads but positive for ULSD and B50 and negligible for PME at medium-to-high loads. CO and CO2 emissions decrease. HC decreases at medium-to-high loads, but increases at low loads. NOx emission increases for PME only but NO2 increases for the three liquid fuels. Smoke opacity, particle mass and number concentrations are all reduced for the three liquid fuels.

A novel and quick method to avoid H2O2 interference on COD measurement in Fenton system by Na2SO3 reduction and O2 oxidation

Hydrogen peroxide interference on chemical oxygen demand (COD) measurement has been a big problem in the application of the Fenton process. However, there is no simple and effective method available to address this problem, although several methods have been reported in the literature. In this study, a new method has been developed based on Na(2)SO(3) reduction and O(2) oxidation, which has easy operation and short time requirement. Na(2)SO(3) reduction was used to remove H(2)O(2) in water samples, which was independent of pH in the investigated range of 2.50-11.95. Residual Na(2)SO(3) was removed by subsequent O(2) oxidation, and effects of initial solution pH, ferric ion dosage, and stirring speed were explored. Solution pH below 3.0 and stirring speed of 700 rev min(-1) could ensure a sufficiently high oxidation rate for Na(2)SO(3) with ferric ion higher than 0.469 mM. This new method was proven to be effective in the matrix of Fenton treating real landfill leachate. Meanwhile, the procedure for this method in other applications was proposed in detail. To the best of our knowledge, this newly developed method is the most simple and effective way to avoid H(2)O(2) interference on COD analysis.

Effects of electrodeposition parameters on morphology and properties of Zn–TiO2 composite coating

Compared to metallic coating, composite coating has more significant mechanical and tribological properties. In this study, titania particles that were codeposited with zinc on a plain carbon steel substrate were used as reinforcements. In addition, the mechanical and tribological properties of these coatings were studied. The effects of bath temperature, stirring rate of electrodeposition solution and concentration of titania in bath on the morphological, mechanical and tribological properties were also investigated. The electrodeposited samples were observed with optical microscope, scanning electron microscope and atomic force microscope. Then, the microhardness and wear properties of the samples were measured. Finally, the optimum degrees of these parameters were achieved to attain maximum codeposition of reinforcement particles, hardness degrees and wear resistance of coatings. The optimised degrees of bath temperature, solution stirring rate and titania concentration in the bath were found to be 40°C, 300 rev min−1 and 5 g L−1 respectively.

Tribological behaviour of AISI 316L stainless steel for biomedical applications

The aim of this research is to study the tribological behaviour of AISI 316L stainless steel for surgical implants (total hip prosthesis). The tribological behaviour is evaluated by wear tests, using tribometers ball on disc and sphere on plane. These tests consisted of measuring the weight loss and the friction coefficient of stainless steel (SS) AISI 316L. The oscillating friction and wear tests have been carried out in ambient air with an oscillating tribotester in accord with standards ISO 7148, ASTM G99-95a and ASTM G133-95 under different conditions of normal applied load (3, 6 and 10 N) and sliding speed (1, 15 and 25 mm s−1). A ball of 100Cr 6, 10 mm in diameter, is used as counter pairs. These tribological results are compared with those carried out with a tribometer type pin on disc under different conditions of normal load applied P (19·43, 28 and 44 N) and sliding speed (600 and 1020 rev min−1). The behaviour observed for both samples suggests that the wear and friction mechanism during the tests is the same, and to increase the resistance to wear and friction of biomedical SS AISI 316L alloy used in total hip prosthesis (femoral stems), surface coating and treatment are necessary.

Experimental investigation of performance and emission improvement by altering ignition timing with use of E10 ethanol blend in SI engine

In this study, the best ignition timing for an SI engine with the use of E10 ethanol blend was experimentally investigated. Ignition timing was retarded successively by 2° up to 6° at most (denoted as −2, −4 and −6 respectively) and then advanced by 2° successively up to 6° (denoted as +2, +4 and +6 respectively) with respect to the advance values realised with gasoline (termed as ‘original advance values’) at full load operation. It was generally observed that overall efficiency increases with advanced ignitions. The best performance and emissions were obtained with +4. This increase amounts to 6% for 4° advanced ignition at 3000 rev min−1. Advanced ignition timing resulted with increase in NOx emissions, while CO and CO2 remained relatively unaffected. Increasing retard in ignition timing caused poorer combustion and hence more fuel consumption but less hydrocarbon emissions.

Preparation and characterisation of amorphous silica/anatase composite through mechanochemical method

In order to solve the issues in the production and application of titanium dioxide, an amorphous silica/anatase composite was prepared through mechanochemical method. The prepared composite was characterised by laser particle size analyser, hiding power test, X-ray diffraction, SEM and infrared spectroscopy methods. The results showed that the properties of the composite are similar to those of titania. The optimum ratio of amorphous silica to anatase, rotation speed, reaction time, slurry density and dispersants amount for the preparation of the composite are 3∶7, 1400 rev min−1, 80 min, 10% and 4% respectively. The hiding power of the amorphous silica/anatase composite could reach 13·07 g m−2, which is better than pure anatase, indicating that the composite could replace titanium dioxide in some areas.

THE EFFECT OF ROTATIONAL SPEED OF THE DRUM ON PHYSICAL PROPERTIES OF GRANULATED COMPOST FERTILIZER

Granulation is one of the fundamental operations in particulate processing which has an ancient history and a widespread use. Compost fertilizer was granulated using drum granulation method under different level of drum rotational speed. Rotational speed of the drum (ω) ranged from 40 to 60 rev min -1 (40, 45, 50, 55 and 60 rev min -1 ). The effect of rotational speed of the drum (ω) on some physical properties of granulated compost fertilizer including: useful granules, granules size, fracture force, mass of the granules, bulk density, angle of friction and angle of repose are investigated in the present study.Results indicated that with the increasing drum rotational speedthe percentage of useful granules, fracture force, bulk density, angle of friction and angle of reposeincrease from 69.91% to 80.88%, 34.35 N to 35.23 N, 743.23 to 765.08 kg m -3 , 26.50 to 28.01o and 10.83 to 12.88o, respectively. Also the average size of granules decreases from10.15 to 7.05 mm.

Effects of leucine and its metabolite β‐hydroxy‐β‐methylbutyrate on human skeletal muscle protein metabolism

Maintenance of skeletal muscle mass is contingent upon the dynamic equilibrium (fasted losses–fed gains) in protein turnover. Of all nutrients, the single amino acid leucine (Leu) possesses the most marked anabolic characteristics in acting as a trigger element for the initiation of protein synthesis. While the mechanisms by which Leu is ‘sensed’ have been the subject of great scrutiny, as a branched-chain amino acid, Leu can be catabolized within muscle, thus posing the possibility that metabolites of Leu could be involved in mediating the anabolic effect(s) of Leu. Our objective was to measure muscle protein anabolism in response to Leu and its metabolite HMB. Using [1,2-13C2]Leu and [2H5]phenylalanine tracers, and GC-MS/GC-C-IRMS we studied the effect of HMB or Leu alone on MPS (by tracer incorporation into myofibrils), and for HMB we also measured muscle proteolysis (by arteriovenous (A–V) dilution). Orally consumed 3.42 g free-acid (FA-HMB) HMB (providing 2.42 g of pure HMB) exhibited rapid bioavailability in plasma and muscle and, similarly to 3.42 g Leu, stimulated muscle protein synthesis (MPS; HMB +70%vs. Leu +110%). While HMB and Leu both increased anabolic signalling (mechanistic target of rapamycin; mTOR), this was more pronounced with Leu (i.e. p70S6K1 signalling ≤90 min vs. ≤30 min for HMB). HMB consumption also attenuated muscle protein breakdown (MPB; −57%) in an insulin-independent manner. We conclude that exogenous HMB induces acute muscle anabolism (increased MPS and reduced MPB) albeit perhaps via distinct, and/or additional mechanism(s) to Leu.

Electrochemical and physical characterization of Pt–Ru alloy catalyst deposited onto microporous–mesoporous carbon support derived from Mo2C at 600 °C

The electrochemical reduction of oxygen on binary Pt–Ru alloy deposited onto microporous–mesoporous carbon support was studied in 0.5 M H2SO4 solution using cyclic voltammetry, rotating disk electrode (RDE), and impedance method. The microporous–mesoporous carbon support C(Mo2C) with specific surface area of 1,990 m2 g−1 was prepared from Mo2C at 600 °C using the chlorination method. Analysis of X-ray diffraction, photoelectron spectroscopy, and high-resolution transmission electron microscopy data confirms that the Pt–Ru alloy has been formed and the atomic fraction of Ru in the alloy was ∼0.5. High cathodic oxygen reduction current densities (−160 A m−2 at 3,000 rev min−1) have been measured by the RDE method. The O2 diffusion constant (1.9 ± 0.3 × 10−5 cm2 s−1) and the number of electrons transferred per electroreduction of one O2 molecule (∼4), calculated from the Levich and Koutecky–Levich plots, are in agreement with literature data. Similarly to the Ru/RuO2 system in H2SO4 aqueous solution, nearly capacitive behavior was observed from impedance data at very low ac frequencies, explained by slow electrical double-layer formation limited by the adsorption of reaction intermediates and products into microporous–mesoporous Pt–Ru–C(Mo2C) catalyst. All results obtained for C(Mo2C) and Pt–Ru–C(Mo2C) electrodes have been compared with corresponding data for commercial carbon VULCAN® XC72 (C(Vulcan)) and Pt–Ru–C(Vulcan) electrodes processed and measured in the same experimental conditions. Higher activity for C(Mo2C) and Pt–Ru–C(Mo2C) has been demonstrated.

Characterisation of amorphous phosphate coatings onto carbon steel surfaces

This study continues the authors’ investigation of the newly developed product KAF-09OF and concerns the preparation and characterisation of amorphous phosphate coatings on carbon steels. KAF-09OF is a liquid concentrate of ammonium and alkaline phosphates, stabilising additives – buffers, softeners, activators (both inorganic and organic), as well as surfactants – a non-ionic and an anionic detergents. Gravimetric and polarisation methods, X-ray fluorescence analysis, transmission electron microscopy, X-ray photoelectron spectroscopy and atomic force microscopy have been used to determine the effect of pH (2–6), temperature conditions (20–80°C) and agitation rate (0–2000 rev min−1) on the process of phosphating using this developed product. Coating thicknesses, compositions, structures and passivation characteristics in the phosphating baths with different concentrations of KAF-09OF have been analysed.

Effect of maleimide curing on mechanical properties of ground tyre rubber/waste polypropylene blends

Blends of ground tyre rubber and waste polypropylene with a maleimide curing system (50∶50 blends of ground tyre rubber/waste polypropylene) were prepared in a Haake Rheocord Polylab System, at 180°C and 90 rev min–1 for 5 min. The curing agent and the activator used were N,N′-meta-phenylene dimaleimide (HVA-2) and di(tert-butylperoxyisopropyl) benzene (DTBPIB) respectively. The HVA-2 level varied from 0 to 5 parts per hundred parts (pphp), while the DTBPIB level varied from 0 to 1 pphp. Melt viscosity, tensile strength and elongation at break showed an increase with HVA-2 content, while the impact energy showed an optimum at 3 pphp level. The addition of the DTBPIB increased melt viscosity further and produced a homogeneous phase morphology of the blends. Impact energy improved with the DTBPIB level, while elongation at break and tensile strength showed an optimum at 0·6 pphp. Swelling behaviour and gel/sol from the boiled xylene extractions were studied, and the results obtained were correlated with the impact and tensile properties.

Utilising friction spot joining for dissimilar joint between aluminium alloy (A5052) and polyethylene terephthalate

The weld strength of thermoplastics with aluminium alloy, such as high density polyethylene and polypropylene sheets, is influenced by friction stir welding parameters. This paper focuses on the preliminary investigation of joining parameter at various levels as well as the mechanical properties of friction spot joining (FSJ) of aluminium alloy (A5052) to polyethylene terephthalate (PET). A number of FSJ experiments were carried out to obtain optimum mechanical properties by adjusting the plunge speed and plunge depth in the ranges of 5–40 mm min−1 and 0·4–0·7 mm respectively, while spindle speed remains constant at 3000 rev min−1. The results indicated that A5052 and PET successfully joined with the aid of frictional heat energy originated from the friction spot welding process. The effect of plunge speed on the joined area and the effect of formation of bubbles at the interface of joints on the shear strength of joint are discussed.

Synthesis and characterisation of urea–formaldehyde microcapsules containing electrophoretic fluid with red–white particles

A series of functional microcapsules were prepared via in situ polymerisation technology with poly(urea–formaldehyde) resin as wall material and electrophoretic fluid containing red–white particles as core materials. The urea–formaldehyde microcapsules were characterised by optical microscopy, scanning electron microscopy and particle size analysis. It was found that sodium dodecyl sulphate (SDS) plays an important role in the formation of the microcapsule wall, and the concentration of SDS mainly affects the yield and surface feature of the microcapsules. The microcapsules prepared with SDS concentration of 2·5×10−3 mM at a dispersing stirring rate of 600 rev min−1 demonstrated good surface topography and suitable sizes. These microcapsules were applied successfully to prepare a clock display operated at a direct current voltage of 20 V, demonstrating that these microcapsules are potential candidates for applications in the area of electrophoretic displays.

Modeling and optimization of poly(3hydroxybutyrate-co-3hydroxyvalerate) production from cane molasses by Azohydromonas lata MTCC 2311 in a stirred-tank reactor: effect of agitation and aeration regimes

The effects of agitation and aeration rates on copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] production by Azohydromonas lata MTCC 2311 using cane molasses supplemented with propionic acid in a bioreactor were investigated. The experiments were conducted in a three-level factorial design by varying the impeller (150-500 rev min(-1)) and aeration (0.5-1.5 vvm) rates. Further, the data were fitted to mathematical models [quadratic polynomial equation and artificial neural network (ANN)] and process variables were optimized by genetic algorithm-coupled models. ANN and hybrid ANN-GA were found superior for modeling and optimization of process variables, respectively. The maximum copolymer concentration of 7.45 g l(-1) with 21.50 mol% of 3HV was predicted at process variables: agitation speed, 287 rev min(-1); and aeration rate, 0.85 vvm, which upon validation gave 7.20 g l(-1) of P(3HB-co-3HV) with 21 mol% of 3HV with the prediction error (%) of 3.38 and 2.32, respectively. Agitation speed established a relative high importance of 72.19% than of aeration rate (27.80%) for copolymer accumulation. The volumetric gas-liquid mass transfer coefficient (k (L) a) was strongly affected by agitation and aeration rates. The highest P(3HB-co-3HV) productivity of 0.163 g l(-1) h(-1) was achieved at 0.17 s(-1) of k (L) a value. During the early phase of copolymer production process, 3HB monomers were accumulated, which were shifted to 3HV units (9-21%) during the cultivation period of 24-42 h. The enhancement of 7.5 and 34% were reported for P(3HB-co-3HV) production and 3HV content, respectively, by hybrid ANN-GA paradigm, which revealed the significant utilization of cane molasses for improved copolymer production.

Simulation study of tertiary current distributions on rotating electrodes

The tertiary current distributions on rotating electrodes have been studied by using the numerical simulation method. An acid copper sulphate electrolyte composed of 0·3M CuSO4 and 1·9M H2SO4 was used within an electrochemical cell of practical dimensions. The rotating disc had a diameter of 6 mm, within which the working electrode with diameter of 3 mm was located at the bottom centre of the disc. The distributions of ion concentrations were obtained by two-dimensional fluid flow simulation and the solution of mass transport equations based on axial symmetry. The calculated concentration boundary layer thicknesses agree well with those obtained from the Levich equation. It is found that the tertiary current distribution on the working electrode is affected by the rotating velocity of the electrode, even if currents are considerably below the limiting current. The effect disappears with the increase in rotating velocity up to 1000 rev min−1 in comparison with the secondary current distribution. The tertiary current distributions for three types of working electrode have been calculated and an improved shape of working electrode is proposed. Since the working electrode is normally used for electrochemical measurements, e.g. polarisation characteristics, which are applied for the calculation of current distribution in the present work, the present study would provide beneficial results to improve the accuracy of measurements.

Influences of welding parameters on mechanical properties of AZ31 friction stir spot welds

In this study, the influence of welding parameters, including tool rotational speed, plunge rate and dwell time, on the overlap tensile shear properties of AZ31 friction stir spot welds was investigated. The microstructures in stir zones and fracture surfaces were observed using optical microscope and scanning electron microscope respectively. The bonded width and h value (the distance from the tip of the partially bonded region to the top of the weld surface) were measured. The results indicated that larger bonded width and higher h value of the AZ31 weld result in better mechanical property. It is proposed that high tensile shear loads are produced when the tool rotational speed range of 1500–2250 rev min−1 and 1 s dwell time are applied during the friction stir spot welding of AZ31. The plunge rate range from 2·5 to 10 mm s−1 has insignificant influence on the tensile shear load of AZ31 joints under the present conditions. The failure mode changes from interfacial to pullout when the tool rotational speed is >2250 rev min−1. The fracture feature of AZ31 welds is brittle fracture.

Effect of weld conditions on microstructures and mechanical properties of friction stir welded joints on AZ31B magnesium alloys

The rotational direction of the friction stir welding (FSW) tool plays a role as important as the weld parameters in FSW processes for magnesium alloys. The formation quality of the weld joints strongly relies on the rotational direction of the stir tool. Based on the present results the better tensile properties of the weld joints are achieved by welding at a higher rotational speed no matter what direction the stir tool rotates. The face bend properties are superior to the root bend properties of the joints. The optimal weld parameters are 1500 rev min−1/90 mm min−1 and 1200 rev min−1/60 mm min−1 for the clockwise and counterclockwise directions of the stir tool respectively. Regardless of the direction which the tool rotates in, fractures of the tensile specimens are mostly located at the boundary between the thermal mechanical affect zone and the nugget zone.

Effect of Thermal Aging on the Corrosion and Microstructure of Friction-Stir Welded Alloy 22

The effect of thermal aging on the corrosion and microstructure of friction-stir welded (FSW) alloy 22 was investigated. Successful welds were produced with a polycrystalline cubic BN pin tool at a rotational speed of 200 rev min−1 and travel speed of 12.7 mm min−1. Topologically closed packed (TCP) phases of ~50 to 300 nm size were identified in the weld nugget. The area fraction of the TCP phases in the weld nugget increased with aging temperature and time. General corrosion rates measured from the weight loss experiments for welds were relatively higher than for parent material. The corrosion rates increased with the increased aging temperature and time. Intergranular corrosion (IGC) resistance is greater in friction-stir welds compared with the parent material at all aging temperatures and times. The IGC depth increased with the aging temperature and time in the parent material. The IGC depth for the FSW weld nugget was minimal and did not change with thermal aging.

Effect of tool travel and rotation speeds on weld zone defects and joint strength of aluminium steel lap joints made by friction stir welding

In this study, Al-5083 and St-12 alloy sheets were friction stir lap welded at different travel (7–23 cm min−1) and rotation (750–1125 rev min−1) speeds of the welding tool. The welded joints were characterised by various methods including shear tensile and Vickers microhardness tests, optical and scanning electron microscopies and X-ray diffraction analysis. The results showed that the weld zone defects decreased, and the joint strength also improved significantly with the reducing tool travel speed from 23 to 7 cm min−1. The travel speed of 11 cm min−1 was an optimum speed within the travel speeds investigated in this work. Additionally, raising the tool rotation speed enhanced the joint strength slightly. The microhardness results confirmed the formation of intermetallic phase layer with the hardness of ∼335 HV at the swirl layered structure.

Characterisation of friction stir welded 7042-T6 extrusionsthrough differential scanning calorimetry

Extruded and T6 tempered plates of 7042, an Sc modified Al–Zn–Mg–Cualloy, were joined by friction stir welding (FSW) at a constantweld velocity and various pin rotation speeds (PRSs). At a low PRS,hardness decreased from each edge of the weld to a local minimum at the weldcentre, but at a high PRS, the hardness initially decreased from each edgeof the weld, but then rose towards the weld centre. The transition in thehardness profile was related to different heating and cooling conditions duringFSW. Differential scanning calorimetry of baseline and welded samples revealedthat the volume fraction of strengthening particles within the weld regionsstrongly depended on the weld conditions. For FSW heating rates, secondaryphase dissolution/precipitation temperatures are in proximity to the weldingtemperatures. The maximum welding temperature during FSW increased from ∼250to 450°C as the PRS increased from 175 to 400 rev min−1.