MPa Injection Pressure Research Articles

Influence of Blending Ratio on Spray Characteristics of Gasoline–Hydrogenated Catalytic Biodiesel Blended Fuel

Blending gasoline with hydrogenated catalytic biodiesel has the potential to improve combustion problems of gasoline direct-injection compression combustion, and the spray characteristics of the blending fuel can directly affect the combustion effect. In order to understand the spray characteristics of a gasoline–hydrocatalyzed catalytic biodiesel mixture, a numerical spray model of constant volume combustion chamber was established, and the accuracy of the model was verified by experimental data in the literature. Based on this model, the spray penetration, sauter mean diameter, spray velocity field and concentration field of gasoline–hydrocatalyzed catalytic biodiesel at different blending ratios were studied. The results show that under the conditions of 850 K ambient temperature, 5 MPa ambient pressure, and 80 MPa injection pressure, as the proportion of hydrogenated catalytic biodiesel in the blending fuel increases, the spray penetration increases, the sauter mean diameter decreases slightly, and the area of high velocity and high concentration at the spray center increases. The results of this study will contribute to the development of blended fuels for superior combustion performance and reduced pollutant emissions at appropriate blending ratios.

An optical study on the spray and combustion characteristics of coal-derived naphtha/diesel blends in a constant volume combustion chamber

ABSTRACT Coal-derived naphtha (CDN) is well suited as an additive for diesel to achieve soot reduction in diesel engines; however, there is no study so far to qualitatively reveal the mechanisms through the spray and combustion processes. In this paper, the spray and combustion characteristics of CDN/diesel blends with 10%, 20%, 30% and 40% CDN in volume were studied under various injection pressures in a constant volume combustion chamber. In addition, gasoline/diesel blend with 20% gasoline in volume was also studied for comparison. Results show that, compared with pure diesel, CDN/diesel blends have the improved fuel spray evaporation, the notably reduced peak integrated natural flame luminosity and soot formation. The blend with 40% CDN shows the greatest soot formation reduction of 39.7% under 100 MPa injection pressure. When the volume fraction of gasoline and CDN are both 20% in blends, there is little difference in spray characteristics, but CDN/diesel blend exhibits a greater advantage in soot formation reduction. Under the test conditions, increasing the injection pressure may improve fuel-air mixing to some extent, but its effect on reducing soot formation is not significant, especially at higher CDN proportions.

A new track for high-efficiency marine diesel engines: Initiative air jet and post-split injection combined

In pursuit of adequate mixing with a high volume of fuel injection, a re-intake scheme is proposed to promote the diffusion of combustibles and flames by using the disturbance of high-pressure air jets after the pressure peak. The results indicate that during the power stroke, an additional air jet enhances combustion by penetrating the spray and disturbing the flame front. The high-pressure air jet's obstruction of the atomization of local sprays achieves a longer combustion duration, while intensifying the vortex and temperature at the cylinder center, which enhances the evaporation of fuel near the nozzle. However, excessively high fuel injection pressure brings in more cold air, causing a temperature drop. It is necessary to have sufficient flame expansion before re-intake to eliminate the impact on pressure. By adjusting the re-intake pressure and timing, the air jet, when it reaches half the cylinder diameter, can exert its maximum advantage. By introducing post-injection and increasing the pressure of the first fuel injection, the air-spray impingement duration is extended, thereby improving thermal efficiency. This work, at 190 MPa injection pressure without changing the duration, and combined with a 5°CA re-intake, achieved a 1.82 % increase in thermal efficiency.

Molecular simulation of free CO2 injection on the coal containing CH4 structure and gas replacement

Understanding the replacement process of pre-adsorbed CH4 by injecting CO2 into the coal slit pores is crucial for CO2 storage and coalbed methane (CBM) extraction. We constructed the model of free CO2 injection into coal containing CH4, and used molecular simulation methods to analyze the replacement and diffusion of gas in coal as well as the coal structure deformation at different CO2 injection pressures. Results indicated that the CO2 adsorption following injection aligned with Langmuir law, and CO2 replaced CH4 more efficiently at 6 MPa injection pressure; After CO2 injection, the coal slit pore volume increased, the coal matrix aromatic structure destroyed, the coal matrix micropores volume increased and expanded radially and compressed longitudinally. Among them, the coal matrix deformation facilitated CO2 adsorption whilelittle impacting the CH4 desorption within the micropores. Higher CO2 injection pressure reduced the diffusion coefficients of adsorbed and free CH4 and CO2, but increased the CO2 adsorption depth in the coal matrix and enhanced the CO2 adsorption stability. The results provided valuable insights into the potential mechanisms of CO2-ECBM.

Thick Columnar-Structured Thermal Barrier Coatings Using the Suspension Plasma Spray Process

Higher operating temperatures for gas turbine engines require highly durable thermal barrier coatings (TBCs) with improved insulation properties. A suspension plasma spray process (SPS) had been developed for the deposition of columnar-structured TBCs. SPS columnar TBCs are normally achieved at a short standoff distance (50.0 mm–75.0 mm), which is not practical when coating complex-shaped engine hardware since the plasma torch may collide with the components being sprayed. Therefore, it is critical to develop SPS columnar TBCs at longer standoff distances. In this work, a commercially available pressure-based suspension delivery system was used to deliver the suspension to the plasma jet, and a high-enthalpy TriplexPro-210 plasma torch was used for the SPS coating deposition. Suspension injection pressure was optimized to maximize the number of droplets injected into the hot plasma core and achieving the best particle-melting states and deposition efficiency. The highest deposition efficiency of 51% was achieved at 0.34 MPa injection pressure with a suspension flow rate of 31.0 g/min. With the optimized process parameters, 1000 μm thick columnar-structured SPS 8 wt% Y2O3-stabilized ZrO2 (8YSZ) TBCs were successfully developed at a standoff distance of 100.0 mm. The SPS TBCs have a columnar width between 100 μm and 300 μm with a porosity of ~22%. Furnace cycling tests at 1125 °C showed the SPS columnar TBCs had an average life of 1012 cycles, which is ~2.5 times that of reference air-plasma-sprayed dense vertically cracked TBCs with the same coating thickness. The superior durability of the SPS columnar TBCs can be attributed to the high-strain-tolerant microstructure. SEM cross-section characterization indicated the failure of the SPS TBCs occurred at the ceramic top coat and thermally grown oxide (TGO) interface.

Experimental characterization of early, quasi-steady and post-injection evolution of single-hole direct injection sprays for spark-ignited engines

The atomization characteristics of the ethanol-gasoline (E85) blended fuel using a single-hole GDI atomizer were studied. The spray at early development, quasi-steady, and post-injection stages were studied in the near-nozzle region. A Galilean-type beam expander and an achromatic lens were used to achieve the desired magnification. In the early development stage, the jet velocity was measured to estimate the breakup regime based on the Ohnesorge (Oh) and Reynolds (Re) numbers. Spray during the initial stage at 2 MPa injection pressure shows second wind-induced breakup under 0.6 MPa chamber pressure (Pch). A transition between second-wind and atomization breakup for jets under 0.03 and 0.05 MPa Pch. The jet experiences atomization breakup under 0.1 MPa Pch. The effect of the injection pressure and chamber temperature were also studied. The post-injection liquid sheet formation near the nozzle exit was observed. Results show that the size of the liquid sheet depends on the liquid-to-gas density ratio (ρlg). The size of the sheet for E85 fuel at ρlg of 2363 was found to be 6 mm, which was reduced by 75 % with a reduction in ρlg by 95 %. The chamber temperature increased from 303 K to 363 K, ρlg increased from 702 to 842, and a reduction in the liquid sheet was observed from 2.5 mm to 1.8 mm, respectively. The necking phenomenon of the liquid sheet was observed at the nozzle tip before the sheet detached and disintegrated into droplets. The necking length for the E85 was compared with gasoline fuel.

Effects of Nozzle Diameter and Holes Number on the Performance and Emissions of a Gasoline Direct Injection Engine

The goal of the current study is to estimate how a gasoline direct injection (GDI) engine's performance and emissions are affected by the fuel injector nozzle diameter and hole number of its injectors. A thermodynamic mathematical modelling has been created utilizing a software program written in the MATLAB language to simulate the two-zone combustion process of a four-stroke direct injection engine running on gasoline at (Rotation Engine Speed 3000 revolution per minute (rpm), 40 MPa injection pressure, compression ratio 9.5, and spark timing 145°). The first law of thermodynamics, equation of energy, mass conserving, equation of state, and mass fraction burned were all used in the creation of the software program. The study was carried out at five different nozzle diameters (0.250, 0.350, 0.450, 0.550, and 0.650 mm) and nozzle hole numbers (4,6,8,10,12). The results show that the GDI engine's performance and emissions are significantly influenced by variations in nozzle hole diameter and number. It was shown that engine power, heat transfer, cylinder pressure, and temperature increased with increasing nozzle hole diameter and number of nozzle holes and the maximum value was seen with nozzle hole diameter 0.650 mm and (12) holes. The lowest value for the nozzle hole diameter and number of holes was found to be 0.250 mm and 4 nozzle holes, which resulted in the lowest emissions of carbon monoxide CO and nitrogen monoxide NO. The study was also conducted for different operating conditions (Rotation Engine speed of 1000, 2000, 3000, 4000, 5000 rpm ,35 MPa injection pressure , compression ratio of 11.5 , and spark timing of 140° ) and the same nozzle diameters and nozzle holes number mentioned previously to estimate the maximum values for temperature, pressure, power , heat transfer and emissions . The results of the second part of the study showed that the highest of maximum values of temperature, pressure, and emissions were at of 1000 rpm, a nozzle diameter of 0.650 mm, and (12) holes. The highest values for maximum power at 4000 rpm, a nozzle diameter of 0.650 mm and (12) holes, while the highest maximum values for heat transfer are at 5000 rpm, a diameter of 0.65mm and (12) holes.

Investigation on the combined influence mechanism of port water injection timing, injection pressure and ignition timing on natural gas engine performance based on the Taguchi method

For the engine with port water injection, the control parameters including injection timing, injection pressure and ignition timing are critical to balance engine performance. To maximize the advantages of water injection, a series of experiments and simulations were conducted to investigate the separate effects of the control parameters on the combustion and emission. Then, the Taguchi method with an L16 orthogonal array was used to study the combined effects of the control parameters. In addition, the engine performance was considered to evaluate the influence degree of the control parameters using the signal-to-noise ratio and the analysis of variance. The result showed that injection timing and injection pressure played an important role in the spark ignition engine. The three-body effect outweighed the thermal effect with the delay of water injection timing, which accelerated the combustion progress and increased the NOx emission. Secondly, ignition advance eliminated combustion deterioration caused by port water injection. Thirdly, the combination of the control parameter of the optimum combustion characteristic and the lowest emission was acquired. The optimum combustion characteristic was acquired at 310 °CA injection timing, 5.0 MPa injection pressure and 44 °CA ignition timing. The lowest emission was acquired at 350 °CA injection timing, 10.6 MPa injection pressure, and 44 °CA ignition timing. Injection timing affects the combustion and emission more than injection pressure.

Laser ignition and flame propagation of methanol-air mixture in a constant volume combustion chamber

ABSTRACT The combustion performance of laser-ignited methanol-air mixture in a constant volume combustion chamber was investigated using the Schlieren photography technique. The experimentation was conducted at 5, 7, 9, and 11 MPa fuel injection pressure and 363 K initial chamber temperature using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser of 1064 nm wavelength. The gasoline direct injection (GDI) system was used for injecting the fuel at different pressures inside the chamber. The laser beam is focused into the chamber using a 150 mm focal length lens, and laser energy of 200 mJ was used for all experimentation. The Schlieren system was used for capturing flame propagation of methanol-air mixture for different equivalence ratios. The pressure-time history for equivalence ratio (ϕ) of 0.8, 0.9, and 1.0 was plotted and analyzed at different chamber filling pressures. Flame propagation was found faster for ϕ of 1.0 due to higher laminar velocity than 0.8 and 0.9. Flame visualization showed that the flame attains the ellipsoid shape during the early stage of ignition. It generates two lobes in the vertical direction and then again expands in a horizontal direction toward the ignition source. For all equivalence ratios, the flame propagation toward the incoming laser source (X-) was observed faster compared to the flame propagation in the direction and perpendicular to the laser beam direction. For all equivalence ratios, higher laminar flame speed was observed at 5 MPa injection pressure; however, it decreases as the injection pressure increases. At ϕ of 1.0 and 11 MPa injection pressure, the maximum peak pressure of 0.67 MPa and combustion duration of 19.3 ms were noted. At 9 MPa injection pressure and ϕ of 1.0, the peak pressure and combustion duration was found as 0.61 MPa and 19.4 ms, respectively. At ϕ of 0.8, the peak pressure and combustion duration were observed 0.27 MPa with 34.6 ms duration and 0.47 MPa with 36.9 ms duration at 5 MPa and 11 MPa injection pressures, respectively.

Effects of 2-ethylhexyl nitrate (EHN) on combustion and emissions on a compression ignition engine fueling high-pressure direct-injection pure methanol fuel

Green methanol is a good carbon–neutral fuel, but the cetane number of methanol is so low that it is unsuitable for use in conventional compression ignition engines. Stable combustion of methanol is a great challenge at low load. Cetane improver such as 2-ethylhexyl nitrate (EHN), can improve the combustion stability of low cetane number fuel. In the current work, the effects of EHN on combustion and emissions were studied on a compression ignition engine at low load by using pure methanol fuel. Four methanol fuels with different EHN addition ratios were used, namely 0 % EHN (pure methanol), 0.1 % EHN, 1 % EHN and 3 % EHN, and diesel was used as the baseline. Results show that compared with diesel, the shortened combustion duration of pure methanol is mainly caused by the shortening of premixed combustion phase. The brake thermal efficiency (BTE) of pure methanol is relatively higher than that of diesel at 120 °C intake temperature. But the BTE of diesel at 50 °C intake temperature is slightly higher than that of pure methanol. As the ENH increases, the ignition delay decreases gradually, and the BTE decreases first and then increases. The NOx emissions of methanol are lower than those of diesel, but NOx emissions increase with the increase of EHN. NOx emissions of 3 % EHN are 31 % more than those of pure methanol and 77 % less than those of diesel. The soot emissions are close to zero for all test methanol fuels. The BTE of all fuels increases initially and decreases subsequently with the delay of start of injection. The higher EGR rate, lower intake temperature and injection pressure improve the BTE of all fuel. For 3 % EHN, the lowest intake temperature is not higher than 40 °C for stable operation, and the optimal operating strategy for the highest BTE (30.5 %) is single injection, 25 MPa injection pressure, 15 % EGR rate and 40 °C intake temperature. Methanol shows 0.6 % higher optimal BTE than diesel at the operating condition.

Evaluation of multi-hole diesel injectors spray under evaporating conditions: Effects of adjacent spray plumes on the macroscopic and mixture characteristics of target spray

Previously, diesel sprays of multi-hole injectors were simulated in an environment where only a single spray plume was simulated. Although boundaries were declared as symmetry, the impact of aerodynamic forces between spray plumes was always neglected. In the present work, all spray plumes of diesel injectors are simulated in a cylindrical box mesh considering external effects including umbrella angle, space between nozzle holes, and hole length to hole diameter ratio. To examine the nozzle hole size effect, two 10-hole diesel injectors with hole diameters of 0.101 and 0.133 mm are investigated under 120 MPa injection pressure. Likewise, to understand the effect of injection pressure, the 0.101 mm hole diameter injector is studied under 120 and 140 MPa rail pressures. In experiments, Laser Absorption Scattering diagnostic technique is applied to visualize the vapor phase, measure mixture concentration and characterize air entrainment. Since Diesel fuel does not absorb UV light, Tracer fuel with the composition of 97.5% of n-tridecane and 2.5% α-Methylnaphthalene is used. On the contrary, sprays are simulated in the Eulerian-Lagrangian two-phase fluid framework using KHRT Breakup and Multicomponent Evaporation models. Parameters such as injection rate and initial spray trajectory angle are measured experimentally and used as input for the spray simulation. Computational results correspond with experiments particularly in terms of Penetration and Equivalence Ratio while Spray Angle deviates.

Effects of full transient Injection Rate and Initial Spray Trajectory Angle profiles on the CFD simulation of evaporating diesel sprays- comparison between singlehole and multi hole injectors

This paper investigates experimental and computational diesel sprays of single hole and multi hole injectors under vaporizing conditions. Two single hole and two ten-hole injectors with the same nozzle hole size are tested with the 120 MPa injection pressure. Experiments implement Laser Absorption Scattering technique. This method utilizes two wavelengths (Visible and Ultraviolet) of light and fuel's mixture concentrations are measured by attenuations of these lights. On the other hand, sprays are simulated in the Eulerian Langrangian two-phase fluid framework where KHRT and Multicomponent models are used as droplet breakup and evaporation models respectively. Full transient profiles of Injection Rate and Initial Spray Trajectory Angle are used as input boundary conditions for the spray simulation and effects on the spray characteristics are observed. Injection rates are measured with Bosch Long Tube and Initial Spray Trajectory Angles are extracted from the near nozzle field spray images. Experiments reveal that multi-hole injectors (0.101 mm and 0.133 mm) injectors depict longer liquid and shorter vapor penetrations. However, longer simulation liquid and vapor penetrations are seen for single hole injectors due to increased initial ramp-up phase. Sprays of Multi-hole injectors are diffused radially which promote air entrainment, better mixture formation, improved combustion, and lower exhaust emissions. Overall, simulated sprays using unfiltered injection rate profile as an input parameter showed an excellent agreement with experiments. While sprays using low-pass filtered injection rates showed a clear disagreement. Parameters including Liquid Length, Vapor Penetration and Evaporation ratios were found to be influenced by the IR profile rather than ISTA. Whereas vapor equivalence ratios depend on both input parameters plus breakup model constants.

A numerical investigation of injector hole configuration and injection parameters in a dimethyl ether fueled DICI engine

AbstractThe lower calorific value of dimethyl ether (DME) is approximately 65% of that of diesel; therefore, a higher quantity of DME must be supplied per cycle to generate the same magnitude of power. A retrofitted DME‐fueled engine generally uses a longer fuel injection duration to provide the excess fuel mass. The present work seeks to find the most appropriate way to increase the mass flow rate of a DME‐fueled direct‐injected compression ignition engine by varying the number of nozzle holes, nozzle hole diameter, and injection pressure. The results show that increasing mass flow rate increases peak combustion pressure and heat release rate but decreases combustion duration. Increasing the number of injector holes increases indicated specific fuel consumption (ISFC) and exhaust emissions (NOx, HC, and CO) due to mixing between unburned fuel spray and neighboring combustion products. Increasing the nozzle hole diameter or fuel injection pressure increases spray tip penetration and improves fuel‐air mixing before combustion initiates. Increasing the nozzle hole diameter by merely 22 μm than the baseline injector reduces ISFC and exhaust emissions at a slightly retarded start of injection (SOI). However, the lowest ISFC was found at the 30 MPa injection pressure at the most advanced SOI, at the expense of higher NOx.

Numerical investigation of the combined effect of injection angle and injection pressure in a gasoline direct injection rotary engine

This study aims to explore the combined effect of injection angle and injection pressure in a gasoline direct injection rotary engine through numerical simulation. Simulation results show that with the increase of injection angle, the fuel impinging position changes from the rotor recess to the middle cylinder block. At the same injection angle, the fuel enrichment area turns to the front of the combustion chamber with the increase of injection pressure. The lower injection angle is helpful to obtain a more uniform fuel distribution. Especially, with increase of injection pressure, the in-cylinder inhomogeneity index presents a downward trend. Under different injection pressures, the flame propagation period of the 0° injection angle is the most stable. The stable flame development and propagation processes make it easy to obtain higher indicated thermal efficiency. The highest indicated thermal efficiency is obtained at 0° injection angle and 15 MPa injection pressure, which is up to 24.99%. Moreover, compared with the fuel intake port injection, part of direct injection strategies help to get higher in-cylinder peak pressure. The higher in-cylinder temperature promotes the formation of NOx, but the organization of the in-cylinder fuel distribution can effectively reduce CO and Soot emissions.

Study on a new method for generating a gas curtain in the gas-curtain launching

To decrease the launching resistance of underwater guns, a new gas-curtain formation method is proposed based on the gas-curtain launching principle, which is setting up several rectangular grooves on the internal wall of the barrel to guide the gas flow to the front of the projectile and form a gas curtain. A three-dimensional unsteady two-phase flow model of the drainage is established. The formation and drainage characteristics of the gas curtain are studied under the different number of grooves with a constant injection area and 10 MPa injection pressure. The results indicate that the circumferential and radial converging effects of multi-gas jets are enhanced, but the axial expansion is enhanced first and then weakened when the number of grooves increases from 4 to 12. The vortex scale in the Taylor cavity increases with the increase in the number of grooves, but the distance moving downstream is shortened. The gas volume fraction in the tube increases with the increase in the number of grooves. However, the drainage efficiency of the gas curtain on the warhead increases first and then decreases with the increase in the number of grooves, while the change of the gas efficiency–cost ratio is just the opposite.

Optimization of Process Parameters for Injection Moulding of Nylon6/SiC and Nylon6/B4C Polymer Matrix Composites

In this research study, the mechanical properties of several Polymer matrix composites are investigated. These composites are multi-phase materials in which reinforcing materials are properly mixed with a polymer matrix. More precisely, Nylon 6 reinforced with 5, 15 and 25 wt. % of silicon carbide (SiC) and Nylon 6 reinforced with 5, 15 and 25 wt. % of boron carbide (B4C), prepared by means of an injection moulding process at three different injection pressures are considered. Specific attention is paid to the tensile and impact strength of these composites. The Taguchi technique is used to optimize the process parameters such as reinforcement material, its percentage and the injection pressure. It is observed that the specimens 5% SiC with 80 MPa injection pressure display a better tensile strength and similarly the specimen 5% B4C with 90 MPa injection pressure have a superior impact strength.

Experimental and numerical studies of rich gas Huff-n-Puff injection in tight formation

Huff-n-Puff technology is considered one of the most effective methods to increase oil recovery in shale reservoirs. Previous works were mainly focused on Bakken and Eagle Ford shales. This paper is devoted to experimental and numerical studies of rich gas injection in core samples with high organic matter content from a tight oil reservoir in Russia. Eighteen core samples from different well intervals and different sizes were used in a Huff-n-Puff experimental study. Eight of the core samples were investigated at an injection pressure of 15 MPa, while ten core samples were studied at near-miscible pressure conditions of 30 MPa. The experiment results indicate that Huff-n-Puff injection of rich gas could give an oil recovery average of 63.03% and a maximum of 88.40% at 30 MPa injection pressure. A compositional model was created utilizing a commercial simulator and history matched to experimental results. The validated model was used to investigate the effect of molecular gas diffusivity, injection pressure, injection duration, shut-in duration, production duration, and other reservoir properties on the recovery factor. Sensitivity analysis by numerical modeling shows that the molecular gas diffusivity was critical in the history matching of the model. The numerical simulation results imply that the recovery factor could be increased by extending the injection period. In contrast, the duration of a soak period does not significantly influence the recovery factor. Furthermore, the recovery factor could be increased by extension of the production due to a slow decline in the pressure gradient between the matrix and fracture at the later stage of the production. The results of the present study imply that the application of the Huff-n-Puff injection of rich gas could increase oil recovery from tight reservoirs.

Spray and combustion characteristics of polyoxymethylene dimethyl ethers and diesel blends in a constant volume chamber

Polyoxymethylene dimethyl ethers (PODE) are newly appeared promising oxygenated additive which can significantly reduce soot emissions of diesel engines. In this study, the spray and combustion characteristics of the blends of diesel with different PODE blending ratio of 0%, 20%, 50% and 100% by volume are investigated in a constant volume chamber (CVC) under 100 MPa, 120 MPa and 140 MPa injection pressures. The spray results show that liquid spray tip penetration (STP), average spray angle (ASA) and spray projected area (SPA) all decrease with PODE blending ratio under 4 MPa ambient pressure and 573 K ambient temperature. The addition of PODE in diesel can significantly reduce the soot formation and the integrated natural flame luminosity (INFL). Under 100 MPa injection pressure, the time integral sum KL in whole combustion duration of D100, P20, P50 and P100 are namely 107.35, 2.66, 0.27 and 0.08. When the PODE blending ratio are 50% and 100%, nearly no yellow flame can be observed in the combustion duration. The chemical structure of PODE plays an important role in reducing soot formation.

Investigation on process parameters for injection moulding of nylon 6/SiC and nylon 6/B4C composites

In this research study, the mechanical properties of several Polymer matrix composites are investigated. These composites are multi-phase materials in which reinforcing materials are properly mixed with a polymer matrix. More precisely, nylon 6 reinforced with 5, 15 and 25 wt% of silicon carbide (SiC) and nylon 6 reinforced with 5, 15 and 25 wt% of boron carbide (B4C) by an injection moulding process at three different injection pressures are considered. Specific attention is paid to the yield strength and Heat Distortion Temperature (HDT) of these composites. The Taguchi technique is used to optimize the process parameters such as reinforcement material, its percentage and the injection pressure. It is observed that 25% B4C reinforced PMC with 100 MPa and 80 MPa injection pressure have optimized yield strength and HDT respectively.

A MiniSandwich Experiment with Blended Ca-Bentonite and Pearson Water—Hydration, Swelling, Solute Transport and Cation Exchange

Shaft seals are geotechnical barriers in nuclear waste deposits and underground mines. The Sandwich sealing system consists of alternating sealing segments (DS) of bentonite and equipotential segments (ES). MiniSandwich experiments were performed with blended Ca-bentonite (90 mm diameter and 125 mm height) to study hydration, swelling, solute transport and cation exchange during hydration with A3 Pearson water, which resembles pore water of Opalinus Clay Formation at sandy facies. Two experiments were run in parallel with DS installed either in one-layer hydrate state (1W) or in air-dry two-layer hydrate (2W) state. Breakthrough at 0.3 MPa injection pressure occurred after 20 days and the fluid inlet was closed after 543 days, where 4289 mL and 2984 mL, respectively, passed both cells. Final hydraulic permeability was 2.0–2.7 × 10−17 m2. Cells were kept for another 142 days before dismantling. Swelling of DS resulted in slight compaction of ES. No changes in the mineralogy of the DS and ES material despite precipitated halite and sulfates occurred. Overall cation exchange capacity of the DS does not change, maintaining an overall value of 72 ± 2 cmol(+)/kg. Exchangeable Na+ strongly increased while exchangeable Ca2+ decreased. Exchangeable Mg2+ and K+ remained nearly constant. Sodium concentration in the outflow indicated two different exchange processes while the concentration of calcium and magnesium decreased potentially. Concentration of sulfate increased in the outflow, until it reached a constant value and chloride concentration decreased to a minimum before it slightly increased to a constant value. The available data set will be used to adapt numerical models for a mechanism-based description of the observed physical and geochemical processes.