Maximum Burst Pressure Research Articles

Numerical analysis of the impact of winding angles on the mechanical performance of filament wound type 4 composite pressure vessels for compressed hydrogen gas storage

Transportation relies heavily on petroleum products, forcing the adoption of alternative energy sources like hydrogen. Hydrogen is considered the cleanest fuel for the twenty-first century due to its water-based combustion and no CO2 emissions. However, challenges persist in production, utilization, and storage; employing composite material-based high-pressure storage vessels is increasing in the hydrogen storage sector. The paper analyzes the impact of the winding angles on the mechanical performance of the filament wound Type 4 composite pressure vessels (CPVs) for compressed hydrogen gas storage at 70 MPa. This work examines the individual winding angles and combined angles winding patterns to promote the efficiency of Type 4 CPVs by achieving maximum burst pressure, ensuring safe burst mode, and reducing CPV weight by applying maximum principal stress theory with the aid of the Ansys ACP Prep/Post and static modules. The weight and burst pressure of CPVs are significantly influenced by fiber orientation; a combination of positive and negative helical winding angles promotes higher burst pressure at a lower weight. A hoop angle and intermediate helical angles can be combined to create high-efficiency CPVs that provide mechanical performance comparable to that of a combination of high and low helical angles. Finally, a one-factor-at-a-time (OAT) sensitivity analysis was performed to determine how the winding angle and the thicknesses of layers affect the CPVs' performance. It was found that the performance of the CPVs is significantly influenced by the thicknesses of the wound layers.

Effect of fuel injection pressure on biodiesel blended combustion of Inland River diesel engine

Abstract Compared with ordinary diesel, biodiesel has greater viscosity, density, and flash point, especially under medium and low load, which is easy to cause poor atomization and inadequate combustion. In this paper, an in-line six-cylinder inland river ship diesel engine was used as a model to conduct simulation tests under 50% load of propulsion characteristics to explore the effects of different fuel injection pressures on oil-gas mixing, combustion, and emission of fuel blended with a small percentage of biodiesel. The results show that the increase of fuel injection pressure can enhance the average turbulence intensity in the cylinder as well as increase the relative flow velocity between oil and gas, which is beneficial to the mixture combustion. High fuel injection pressure will promote flame propagation, increasing the maximum burst pressure and the average temperature in the cylinder. Compared to the fuel injection pressure of 24 MPa, NOx emission increases by 5.5% and 15.6% respectively at 27 MPa and 30 MPa, and decreases by 10% and 25% respectively by SOOT.

A tough bioadhesive hydrogel supports sutureless sealing of the dural membrane in porcine and ex vivo human tissue.

Complete sequestration of central nervous system tissue and cerebrospinal fluid by the dural membrane is fundamental to maintaining homeostasis and proper organ function, making reconstruction of this layer an essential step during neurosurgery. Primary closure of the dura by suture repair is the current standard, despite facing technical, microenvironmental, and anatomic challenges. Here, we apply a mechanically tough hydrogel paired with a bioadhesive for intraoperative sealing of the dural membrane in rodent, porcine, and human central nervous system tissue. Tensile testing demonstrated that this dural tough adhesive (DTA) exhibited greater toughness with higher maximum stress and stretch compared with commercial sealants in aqueous environments. To evaluate the performance of DTA in the range of intracranial pressure typical of healthy and disease states, ex vivo burst pressure testing was conducted until failure after DTA or commercial sealant application on ex vivo porcine dura with a punch biopsy injury. In contrast to commercial sealants, DTA remained adhered to the porcine dura through increasing pressure up to 300 millimeters of mercury and achieved a greater maximum burst pressure. Feasibility of DTA to repair cerebrospinal fluid leak in a simulated surgical context was evaluated in postmortem human dural tissue. DTA supported effective sutureless repair of the porcine thecal sac in vivo. Biocompatibility and adhesion of DTA was maintained for up to 4 weeks in rodents after implantation. The findings suggest the potential of DTA to augment or perhaps even supplant suture repair and warrant further exploration.

Study on the formation and ignition law of ignition core in ammonia atmosphere diesel cylinder

Ammonia fuel does not contain carbon and is a kind of very good zero-carbon alternative fuel for diesel engines. However, ammonia is difficult to be ignited in diesel engine. The dual-fuel combustion mode of ammonia and diesel is an effective technical means to solve the problem. In this paper, the 186FA diesel engine test bench was built, and the ammonia/diesel dual fuel combustion mode was formed by injecting 0 %, 10 %, 20 %, 30 %, 40 %, and 50 % ammonia into the inlet and direct injection of diesel into the cylinder. The in-cylinder pressure and heat release laws were measured and analyzed at 2700r/min, 25 % load and 75 % load. Based on the analysis of the oxidation in ignition process of ammonia gas and diesel, a computational fluid dynamics model of the ignition process was established. By comparing the temperature contour surface in the cylinder and the concentration contour surface of OH radical, the paper put forward the ignition core evaluation index suitable for diesel/ammonia dual fuel. The formation law of the ignition core of diesel injected in homogeneous low reactive ammonia atmosphere in the cylinder was analyzed, and the influence of ammonia on the ignition process of diesel was revealed. The results show that the ignition delay period is prolonged after adding ammonia, and there is an exponential function relationship between the ignition delay period and the atmospheric concentration of ammonia. At 1200 K, there is an obvious parabolic relationship between ammonia concentration and OH radical concentration. The ignition core area was increased with the increase of ammonia concentration. Compared with pure diesel mode, the single ignition core at 75 % load of 2700 r/min is 3.6 times larger at 50 % ammonia atmosphere concentration. The ignition core will move up the diesel bundle with the increase of ammonia concentration. The study of chemical reaction kinetics showed that the reaction NH3 + OH = NH2 + H2O displayed positive sensitivity when ammonia concentration was less than 10 % and negative sensitivity when ammonia concentration was more than 10 %. The difference in sensitivity is the reason why the phase of the maximum burst pressure in the 10 % ammonia atmosphere is slightly earlier.

Rapid suture-free repair of arterial bleeding: A novel approach with ultra-thin bioadhesive hydrogel membrane

Arterial injuries, particularly in emergency situations or challenging environments, demand convenient, safe, and efficient repair strategies. Herein, we developed and evaluated a portable, suture-free, ultra-thin arterial repair membrane, referred to as the tissue-adhesive biphasic hydrogel membrane (TBHM). The TBHM was developed using electrospinning technology and a biphasic photosensitive hydrogel, composed of nitrobenzene-modified hyaluronic acid (HA-NB) and methacrylated polyvinyl alcohol (PVA-MA), with lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) as the photoinitiator. The TBHM was characterized by rapid bonding, high adaptability, and the ability to withstand a maximum burst pressure of 441.9 ± 25 mmHg. This membrane is capable of rapidly crosslinking and sealing a wound within 23 s. In vitro cell culture assays validated the biocompatibility and safety of the TBHM. Using a rabbit carotid artery rupture model, the TBHM allowed for immediate suture-free repair. Postoperative CT and Doppler ultrasound examinations confirmed restoration of normal anatomical structure and function. Histopathological analysis and molecular biology tests suggested that TBHM has potential anti-inflammatory and tissue regeneration-promoting properties. This study thus presented the TBHM as a promising novel strategy for the rapid, suture-free repair of arterial injuries, which may revolutionize emergency trauma and hemorrhage control scenarios.

Investigation on a predetermined point of failure for stainless steel 316L pressure loaded components made by laser powder bed fusion through stress analysis and experimental testing

The qualification process of pressure vessels in general is subject to governmental restrictions. Thus, introducing additive manufacturing (AM) components to the market is challenging due to incomplete standardization. To increase component safety and trust, predetermined points of failure can be integrated by design using direct manufacturing methods. A predetermined point of failure using a surface notch is one option to avoid dangerous part failure (e.g. explosion) and increase safety. For implementation, a design approach with experimental proof of concept is striven to guide manufacturers and demonstrate the behavior of the material and the component as a whole. Finite element analysis is used for investigations on the influence of surface notch geometries applied to wall structures on structural stress super-elevation. Analytical strength assessment using FKM guideline and experimental validation of PBF-LB/M-manufactured specimen behavior by static axial tensile and burst testing is carried out. Fracture surface and plastic elongation evaluation using light microscopy and 3-D surface scanning clarify the material behavior. The analytical and experimental approval of an integrated predetermined point of failure for static overload is achieved without reducing the maximum burst pressure value. The integration fulfills all theoretical requirements for structural strength. All tested specimens meet the expectations regarding static strength and failure behavior. As expected, component elongation decreases using surface notches for failure provocation. Results lead to a proposed guideline for the application of an integrated predetermined point of failure by the use of a surface notch.

Effect of Fuel Injection Timing on Marine Diesel Engine Blended with Isoamyl Alcohol

In order to study the problem that the pressure in the cylinder decreases significantly after diesel is mixed with isopentanol, which leads to the reduction of power performance, the software of AVL-FIRE is used for simulation, and the angle of start injection is adjusted to improve cylinder pressure. It turns out that in terms of combustion, The maximum burst pressure is reduced after mixing isoamyl alcohol. By increasing fuel injection timing, maximum burst pressure can rise to 87.8%-94.5% of the original engine respectively. The indicated power can be increased to 91.92%-95.62% of the original. In terms of emissions, after mixing, with the increase of fuel injection timing, NO does not change significantly, Soot shows a downward trend.

Effect of Mixed Firing Ethylene Glycol on Combustion and Emission Performance of Model 4190 Diesel Engine

In order to study the influence of ethylene glycol on the combustion and emission of marine diesel engine, a combustion chamber model was established based on 4190ZLC-2 marine medium speed diesel engine by AVL-FIRE simulation software, and the accuracy of the model was verified. The effects of ethylene glycol on the combustion and emission characteristics of diesel engine under different mixing ratios were studied by simulation experiments, and the optimal mixing ratio of ethylene glycol and diesel was obtained under the premise of ensuring the diesel engine to work at full load. The results show that the average pressure in the cylinder and the maximum burst pressure in the cylinder of the dual-fuel engine mixed with ethylene glycol are decreased compared with the original engine under different mixing ratios. Under full load condition, NOx and soot emissions are decreased by increasing ethylene glycol mixing ratio, and CO emission peak is increased but not significantly increased. Through analysis, it can be concluded that when mixing ratio is 15%, final CO emission decreases by 28.6%, final NO emission decreases by 7.9%, and Soot emission decreases by 16.9%.

Preparation and Evaluation of Bacterial Nanocellulose/Hyaluronic Acid Composite Artificial Cornea for Application of Corneal Transplantation.

The treatment for corneal damage requires donor corneal transplantation, but there is a serious scarcity of donor corneas worldwide. In this study, we aimed to design a new artificial cornea with good cytocompatibility, excellent optical properties and suture resistance, and great moisturizing properties. A new bacterial nanocellulose (BNC) membrane with anisotropic mechanical properties and high light transmission was produced in a horizontal rotary drum reactor. However, as a potential material for artificial keratoplasty, the transparency and mechanical properties of the new BNC membrane were not satisfactory. Thus, hyaluronic acid (HA) was introduced in the BNC to synthesize the BNC/HA composite membrane by using 1,4-butanediol diglycidyl ether (BDDE) as the chemical cross-linking agent. The micro-morphology, light transmittance, mechanical properties, water content, moisture retention ability, and cytocompatibility of the composite membranes were further evaluated. HA was fixed in the BNC network by the ether bond, and the composite membrane was found to have excellent light transmittance (up to 95.96%). The composite membrane showed excellent mechanical properties, for instance, its tensile strength exceeded the human normal intraocular pressure (IOP) (1.33-2.80 kPa), the maximum burst pressure was about 130 kPa, 46-97 times that of the normal IOP, and its suture force was close to that of the human amniotic membrane (0.1 N). Based on the three-dimensional network scaffold of BNC and the high water absorption characteristics of HA, the artificial cornea had high water content and high moisture retention ability. The rabbit corneal stromal cells cultured in vitro showed that the artificial cornea substitute had excellent cytocompatibility. BDDE is the most frequently used cross-linker in most HA products in the current cosmetic medicine industry owing to its long-term safety records for over 15 years. Therefore, the BNC/HA composite hydrogel cross-linked with BDDE has great potential in artificial keratoplasty or ocular surface repair.

Composite Overwrapped Pressure Vessel Design Optimization Using Numerical Method

Composite Overwrapped Pressure Vessels (COPVs) are widely used in fields including aeronautics and by companies such as SpaceX to hold high pressure fluids. They are favored for these applications because they are far lighter than all-metal vessels, although they demand special design, manufacturing, and testing requirements. In this study, finite element modeling was used to conducted stress and damage assessments on a composite overwrapped pressure vessel that has a 4 mm thick aluminum core cylinder. To develop the optimum COPV, the lamina sequences, thickness, and fiber winding angle were considered. The relationship between these variables and the composite-overwrapped structure’s maximum burst pressure bearing capacity was assessed. The ABAQUS composite modeler was used to design and generate 14 models of COPVs from carbon fiber/epoxy plies with a consistent thickness of 6.5 mm and various fiber angle orientations. The effects of the ply stacking order were analyzed by the finite element analysis approach for all designed models, which had 13 layers of uniform thickness but a varying fiber orientation. A ply stacking sequence of [55°, −55°] PP winding pattern had an optimum COPV design profile, with a burst pressure bearing capacity of 24 MPa. The stress–strain distribution along the geometry of the COPV was also obtained using the finite element method, and it was found that the distribution is uniform over the surface of the COPV and that its peak values are found towards the polar boss section of the COPV. Extreme stress gradients were noticed when the boss nears its geometrical transition to the dome phase. This factor is evident from the change in the ply thickness caused by the overlapped fiber orientation. The results obtained from this study are useful for the design and application of composite overwrapped pressure vessels.

A Comparative Study Between Porcine Peritoneum and Pericardium as Cardiovascular Material.

Decellularized porcine pericardium has many applications in the cardiovascular field for its excellent properties. The peritoneum is a single-layer bio-dialysis membrane with many similarities and differences in physical characteristics, biochemical composition, and structure to the pericardium. The limited available literature suggests that, similar to the pericardium, the peritoneum has good application potential in the field of cardiovascular substitute materials. This research focused on comparing the differences between decellularized peritoneum and decellularized pericardium in microstructure, biochemical composition, mechanical properties, hemocompatibility, in vitro enzymatic degradation, in vitro calcification, cytocompatibility, and other vital indicators. The peritoneum was consistent with pericardium in terms of fibrous structure, hemocompatibility, in vitro calcification, and cytocompatibility. The peritoneal elastic fiber content (219 μg/mg) was significantly higher than that of the pericardium (66 μg/mg), resulting in two to three times higher maximum load (21.1 N) and burst pressure (1309 mmHg), and better performance than the pericardium in terms of in vitro resistance to enzymatic degradation. In the cardiovascular field, decellularized peritoneum can be used as vascular substitute material. Impact statement There are many similarities between the embryonic origin and morphological structure of the porcine peritoneum and the porcine pericardium, but little research has been done on the use of the porcine peritoneum as a biomaterial. In this compared research, we showed that porcine peritoneum had better resistance to enzymatic degradation, better stretching, and more suitable burst pressure for being used as vascular substitute material. This research is the first to describe the structural composition of porcine peritoneum and its advantageous properties as a cardiovascular material.

Construction of porous cellulose tubes and the evaluations of mechanical properties and cytocompatibility

AbstractIn this work, regenerated cellulose (RC) tubes with the porous structure were successfully fabricated for constructing the non‐invasive detection platform of vascular microenvironment. Polyethylene oxide (PEO) as a porogen was applied to induce porous structure of cellulose tubes. Tensile and burst pressure tests were carried out to evaluate the effects of PEO molecular weight and amount on the mechanical properties of cellulose tubes. The results showed that tensile strength of RC tubes was increased with increasing PEO molecular weight. The compliance of cellulose tubes decreased with increasing the PEO content. When 120 kDa PEO was applied, the average tensile strength of RC tubes could reach 1.27 MPa. The maximum burst pressure and compliance of RC tubes could reach 488.25 ± 35 mmHg and 7.50 ± 3.7%/100 mmHg, respectively. Human umbilical vein endothelia cells (HUVECs) exhibited obvious proliferation on cellulose tubes, and the collagen coating further improve the biocompatibility. The incorporated collagen further improved adhesion of the cells and growth on cellulose tubes. This work provided a kind of cellulose‐based tube material with potential application for the construction of the vitro vascular microenvironment.

Human Cadaveric Donor Cornea Derived Extra Cellular Matrix Microparticles for Minimally Invasive Healing/Regeneration of Corneal Wounds.

Biological materials derived from extracellular matrix (ECM) proteins have garnered interest as their composition is very similar to that of native tissue. Herein, we report the use of human cornea derived decellularized ECM (dECM) microparticles dispersed in human fibrin sealant as an accessible therapeutic alternative for corneal anterior stromal reconstruction. dECM microparticles had good particle size distribution (≤10 µm) and retained the majority of corneal ECM components found in native tissue. Fibrin–dECM hydrogels exhibited compressive modulus of 70.83 ± 9.17 kPa matching that of native tissue, maximum burst pressure of 34.3 ± 3.7 kPa, and demonstrated a short crosslinking time of ~17 min. The fibrin–dECM hydrogels were found to be biodegradable, cytocompatible, non-mutagenic, non-sensitive, non-irritant, and supported the growth and maintained the phenotype of encapsulated human corneal stem cells (hCSCs) in vitro. In a rabbit model of anterior lamellar keratectomy, fibrin–dECM bio-adhesives promoted corneal re-epithelialization within 14 days, induced stromal tissue repair, and displayed integration with corneal tissues in vivo. Overall, our results suggest that the incorporation of cornea tissue-derived ECM microparticles in fibrin hydrogels is non-toxic, safe, and shows tremendous promise as a minimally invasive therapeutic approach for the treatment of superficial corneal epithelial wounds and anterior stromal injuries.

Effects of Thickness and Winding Angle of Reinforcement Laminates on Burst Pressure Capacity of Thermoplastic Composite Pipes

Abstract The cross section of thermoplastic composite pipes (TCPs) consists of three layers: an inner liner, reinforcement laminates, and an outer jacket; the three layers are fully bonded together to form a solid-walled structure. In this study, the mechanical behaviors of TCPs under internal pressures were investigated using analytical and finite element analysis (FEA) methods. The analytical method that is based on the three-dimensional (3D) anisotropy elastic theory takes into account the nonuniform distribution of stresses and strains through the wall thickness of the pipe. FEA models were setup using the software abaqus to predict the stress distribution of a TCP. The 3D Tsai-Wu failure criterion was used to predict the maximum burst pressure of TCPs. Effects of winding angles and the number of reinforcement plies on the burst pressure of TCPs were studied. Results derived from the analytical method and the FEA method verified each other, which show that the burst pressure of a TCP increases asymptotically as the number of reinforcement plies increases. The optimal winding angle associated with the maximum burst pressure is not a constant value, instead, it varies as the thickness of the laminate layer increases. This study provides useful tools and guidance for the design and analysis of TCPs, while further validation experiments are still needed.

Swine Small Intestine Sealing Performed by Different Vessel Sealing Devices: Ex-Vivo Test.

This study aimed to evaluate the sealing quality of swine small intestine using different laparoscopic radiofrequency vessel sealing devices (two 5 mm: RFVS-1 and -2; one 10 mm: RFVS-3) and a harmonic scalpel (HS) compared to golden standard closure technique. The study was divided into two arms. In study arm 1: n = 50 swine intestinal loops (10 per group) were transected with each instrument and the loops in which the devices provided complete sealing, at the gross inspection, were tested for maximum burst pressure (BP) and histological evaluation and compared to an automatic linear stapler. After the BP tests, the devices that achieved significantly lower BP values were excluded from the second arm. The RFVS-1 and -3 provided statistically significant results and were used in study arm 2, to obtain full-thickness biopsies along the antimesenteric border of the loop and were compared with hand-sewn intestinal closure (n = 30; 10 per group). The biopsies were histologically evaluated for thermal injury and diagnostic features, and intestinal loops tested for BP. RFVS-3 achieved comparable results (69.78 ± 4.23 mmHg, interquartile range (IQR) 5.8) to stapler closing technique (71.09 ± 4.22 mmHg, IQR 4.38; p > 0.05), while the RFVS-1 resulted in significantly (p < 0.05) lower BP (45.28 ± 15.23 mmHg, IQR 24.95) but over the physiological range, conversely to RFVS-2 (20.16 ± 7.19 mmHg, IQR 12.02) and HS (not measurable). RFVS-3 resulted not significantly different (p > 0.05) (45.09 ± 8.75 mmHg, IQR 10.48) than Suture (35.71 ± 17.51 mmHg, IQR 23.77); RFVS-1 resulted significantly lower values (23.96 ± 10.63 mmHg, IQR 9.62; p < 0.05). All biopsies were judged diagnostic. Data confirmed that RFVS-1 and -3 devices provided suitable intestinal sealing, with BP pressures over the physiological range. Conversely, the HS and RFVS-2 should not be considered for intestinal sealing. RFVS devices could be employed to obtain small intestine stump closure or full-thickness biopsies. However, further studies should be performed in live animals to assess the role of the healing process.

Experiments on burst pressure and fragment dispersion effects of small-sized pressure vessel BLEVE

With the purpose of researching the bursting of a small-sized pressure vessel containing high pressure carbon dioxide (CO2) and the dispersion and distribution of the prefabricated fragments, experimental tests were conducted for pressure vessels with V-shaped grooves and X-shaped grooves. Depending on the experimental results, the rupture positions of the two types grooved pressure vessels were different, and the resistance to the pressure of the V-shaped grooved pressure vessels was higher than the resistance to the pressure of the X-shaped grooved pressure vessels. The maximum burst pressure and the average burst pressure of the V-shaped grooved pressure vessels were both higher than those of X-shaped grooved pressure vessels. For the distribution range of the prefabricated fragments, the fragments were concentrated in the range of the fragment radial scattering azimuth angles from −15° to 15° and the axial scattering azimuth angles was from 65.77° to 113.02°. The initial velocity of a fragment was 272.79 m/s, and the prefabricated fragment with that initial velocity had a residual specific kinetic energy of 101.97 J/cm2 when it dispersed beyond 7 m, which could cause damage to organisms.

Effect of Defect Width upon Burst Capacity of Composite Repaired Pipe

In recent years, FRP composite wrap repair is the most preferable pipeline rehabilitation system used in the pipeline industry. However, some issues concerning this repair method are not fully understood by the industry. Effect of defect geometries toward the efficiency of composite repaired pipe is one of the issues that concerned by the industry. Pipeline repair design codes and standards have been developed mainly focus on the defect depth and neglect other defect geometries such as defect length and defect width. Previous studies stated that defect geometries especially defect width should not be ignored in evaluating and designing pipe repair system. Therefore, the burst pressure of the composite repaired pipeline subjected to various defect widths was determined through this study in order to evaluate the effect of defect width upon the burst capacity of composite repaired pipeline. Finite element analysis was used to determine the burst capacity of the composite repaired pipe with rectangular shape of defect. There are three different widths were selected with constant defect length and depth. The base model of composite repaired pipe was developed and validated and then modified with the various defect widths in this study. The result shows that burst pressure for three different models vary with a percentage of 12.51% between the maximum burst pressure and minimum burst pressure. The stress contour plot extracted from the finite element analysis revealed that the area of highest stress (557.7MPa) is located around defect region. As the defect is getting wider and subsequently creating a bigger defect area, stress concentration is also getting larger at the defect region. With this, the composite repaired pipe tends to fail at lower pressure when the defect getting wider. Based on the results, the defect width is proven to affect the burst capacity of composite repaired pipe.

Rapid Manufacturing of Thin Soft Pneumatic Actuators and Robots.

This protocol describes a method for rapid manufacturing of soft pneumatic actuators and robots with an ultrathin form factor using a heat press and a laser cutter machine. The method starts with the lamination of thermoplastic polyurethane (TPU) sheets using a heat press for 10 min at the temperature of ~93 °C. Next, the parameters of the laser cutter machine are optimized to produce a rectangular balloon with maximum burst pressure. Using the optimized parameters, the soft actuators are laser cut/welded three times sequentially. Next, a dispensing needle is attached to the actuator, allowing it to be inflated. The effect of geometrical parameters on the deflection of the actuator are studied systematically by varying the channel width and length. Finally, the performance of the actuator is characterized using an optical camera and a fluid dispenser. Conventional fabrication methods of soft pneumatic actuators based on silicone molding are time consuming (several hours). They also result in strong but bulky actuators, which limits the actuator's applications. Moreover, microfabrication of thin pneumatic actuators is both time-consuming and expensive. The proposed manufacturing method in the current work resolves these issues by introducing a fast, simple, and cost-effective fabrication method of ultrathin pneumatic actuators.

Gaseous Emissions and Particle Microstructure Characteristics of PODE/Diesel Blend Fuel

Polyoxymethylene dimethyl ethers (PODE) has good application prospects as an alternative to diesel fuel with a great potential to achieve clean combustion on diesel engines. In current study, the effects of PODE/diesel blends with PODE volume fraction at 10 %, 20 % and 30 % on performance and emission characteristics are investigated on a common-rail diesel engine under different engine loads. The particle size distribution and microstructure characteristics of the combustion particles are also analized. Results show that the PODE/diesel blends have shorter ignition delay, higher in-cylinder maximum burst pressure and advanced heat release. The brake thermal efficiency increases slightly with the increment of PODE blending ratio. There is a simultaneous improvement in CO, HC and soot emissions when fueling blend fuels. A more obvious shifting tendency toward the direction of small particle size can be found in number concentration, mass density and mass cumulative distribution of particles with increment of PODE. The microstructure of the blend fuels combustion particles is mainly in the form of agglomerates. Compared with diesel fuel, combustion particles of blend fuels have bigger layer spacing and microcrystalline curvature as well as smaller crystallite size, also the box dimension of the particles and the degree of agglomeration increase.

Preliminary study of a control algorithm for radio-frequency-induced intestinal tissue fusion

Purpose: A control algorithm for radio-frequency-induced intestinal tissue fusion was developed to explore the effects of different control parameters on intestinal tissue fusion.Materials and methods: Radio-frequency-induced fusion was performed on ex vivo small intestine tissue. The effect on the fusion was observed by changing the control parameters (power, interval time, and terminal impedance) in the algorithm. The quality of fusion was evaluated using the burst pressure and thermal damage measurement. Histological evaluation was used to assess the fusion quality indirectly.Results: A maximum burst pressure of 8.460 ± 0.2674 KPa was acquired when the power was set to 100 W, the interval time was set to 2000 ms, and the terminal impedance was set to 50 Ω. Moreover, the thermal damage range increased with an increase in power but decreased with an increase in the interval time and terminal impedance. Furthermore, the thermal damage range and temperature were presumably related.Conclusions: For an ex vivo small intestine tissue, the appropriate control parameters could be set when the power was approximately 100 W, the interval time was approximately 2000 ms, and the terminal impedance was approximately 50 Ω. This study could provide a basis for the selection of control parameters for intestinal tissue fusion.