Computational and Experimental Investigations on Biodiesel Combustion Process

The combustion process of liquid conventional and biofuels depend on factors ranging from the thermophysicochemical properties associated with such fuels to the combustion infrastructure used to burn them. A third class of fuels commonly referred to as surrogate fuels can be obtained by mixing conventional and biofuels. It is thought that the existence of oxygen atoms in biofuels play a crucial role in the way they burn in a stream of air, in uencing not only the e ciency of the combustion process of such class of fuels but also the emissions. The mechanisms through which the existing oxygen atoms in uence the combustion process of biofuels (and its surrogates) are still debatable and unestablished. This thesis sheds light on the points mentioned in the paragraph above. Extensive computational and experimental work was done to elucidate the combustion process of conventional, surrogate and biofuels. Some of the reaction mechanisms used in modelling the current reactive ow simulation are already tested while others were developed during the course of this work. The computational results have shown good agreement with the available experimental data. One of the most important observations and ndings reported in this work was that when comprehensive reaction models were used, the injected fuels burned at a slower rate compared to the situation when reduced models were employed. While such comprehensive models predicted better ame structure and far better by-products compared to the existing experimental results, it has also led to di erences in some parameters, especially the temperature eld. The computational prediction has also shown that biodiesel produces a marginally higher rate of COx compared to diesel which was also observed experimentally using a Compression Ignition Engine (CIE). Having said so, the experimental work also showed that surrogate fuels perform far better than pure diesel and biodiesel in CIE) in terms of emissions. The experimental work further addressed some phyisical and spectral analysis of diesel, biodiesel and nine blends as well as assessing the performance of a combination of these fuels in a compression ignition engine. The results are in line with what has reported in the literature but also sheds light on important features related to surrogate fuels and explain better the expected structure of such blends which may in uence the way they burn under di erent environments. With regards to the harmfull emissions of the combustion of liquid fuels, biodiesel was found to produce harmful emissions in a lower quantity compared to conventional diesel which is in line with the ndings of many experimental data. The computational ndings have also predicted less energy content and temperature range for biofuels of order 10-15% which is also in agreement with many experimental ndings cited in the literature

Psychological Stress in Language Learning: A Contemporary View beyond Teaching Methods

The current paper attempts to identify the role of stress in language learning. To achieve this objective, a critique of relevant literature was done by analyzing the concept of stress and how it can be manipulated to help improve the language learning process. Stress was reviewed in terms of its concept, measurement, resources, and management. The recommendation is that language teachers can deal with language learning stress in learners through a stress toolbox: awareness, observing, and management. Keywords: language learning, stress.

Numerical Study of Reacting Flow in a Methane Burner with a Detailed Reaction Mechanism

In this paper, a numerical study of reacting flow in a methane burner using the Reynolds Averaged Navier-Stokes equation (RANS) is presented. A shear-stress transport turbulence model and presumed shape probability density functions (Pdfs) are used. Detailed chemical kinetic mechanism for the methane oxidation with 100 species and a 448 steps reaction has been developed using EXGAS software in this study. Moreover, simulations have been carried out to investigate the applicability of this study. The predicted temperature profiles agreed well with those obtained from Gas Research Institute (GRI) mechanism and the available experimental data. Other variables including CO2 predicted by the GRI and the EXGAS mechanisms also show good agreement

The Experimental Investigation of The performance of Phosphor Coating

Different screen printing parameters have a distinct effect on the quality of coating that is created. This experimental work looked to measure these parameters. It is divided into two parts where the first part measured the surface wettability of various substrates Wettability measurement was performed through measuring the contact angle between the droplet and the substrate surface. Varying the UV exposure time by putting substrate in the UV ozone cleaner has a considerable effect on the wettability of the surface. Water was supplied to a PEDOT: PSS substrate via Fibro DAT 1100 which is attached to a camera and a computer for capturing and analyzing coatings for the spread of a water droplet on the substrate surface. From these analyses, the main aim is to measure the contact angle between the droplet and the substrate surface which indicates the surface wettability. Some factors may affect the wettability of the surface such as varying the UV time and varying the hold time. As a result, increasing these times will decrease the contact angle where a small contact angle indicates a favorable wettability. The second part measured the electrical resistance and transparency of the printed ink after various printing experiments such as implementing UV treatment, changing the ink and changing the mesh ruling. The Rheometer device was used to test the properties of the specimen. Where this device can be used to measure the properties of the specimen such as the shear modules, in this paper the plate was used to effect on the specimens, where different readings are recorded for these specimens. Also, 24 samples were prepared and the electrical resistance for these samples was measured in this paper. As a result, the electrical resistance for treated samples was greater than that for untreated samples; the electrical resistance of Elentan ink was greater than that for PEDOT at the same conditions. Changing the screen size from (61-64) to (40-100) increase the value of resistance at the same conditions. For the transparency measurements the Elentan ink had a higher transparency than PEDOT ink. The paper also carried out an analysis for the relation between the thickness of the phosphor layer and the lamp output, where the relation was inversely proportion

Tribological studies of bamboo fibre reinforced epoxy composites using a BOD technique

To reduce the emission of harmful materials into the ecosystem, researchers have been exploring the potential of manufacturing polymeric composites based on natural fibres. Although the large area of application of these materials has encouraged investigations of their performance under various loading conditions, less research has been conducted on their tribological behaviour. Hence, in this study, tribological tests were conducted on epoxy composites based on bamboo fibres. The wear performance of bamboo fibre reinforced epoxy was tested using various operating parameters, and the worn surfaces were examined using optical microscopy. The results revealed that the specific wear rate of the composites reduced since the epoxy was reinforced with bamboo fibres. Scanning electron microscopy analysis showed different wear mechanisms and damages

Epoxy and polyester composites’ characteristics under tribological loading conditions

This research examines the friction and dry wear behaviours of glass fibre-reinforced epoxy (GFRE) and glass fibre-reinforced polyester (GFRP) composites. Three fibre orientations—parallel orientation (P–O), anti-parallel orientation (AP–O), and normal orientation (N–O)—and various sliding distances from 0–15 km were examined. The experiments were carried out using a block-on�ring configuration at room temperature, an applied load of 30 N, and a sliding velocity of 2.8 m/s. During the sliding, interface temperatures and frictional forces were captured and recorded. Worn surfaces were examined using scanning electron microscopy to identify the damage. The highest wear rates for GFRE composites occurred in those with AP–O fibres, while the highest wear rates for GFRP composites occurred in those with P–O fibres. At longer sliding distances, composites with P–O and N–O fibres had the lowest wear rates. The highest friction coefficient was observed for composites with N–O and P–O fibres at higher sliding speeds. The lowest friction coefficient value (0.25) was for composites with AP–O fibres. GFRP composites with P–O fibres had a higher wear rate than those with N–O fibres at the maximum speed

Effect of Fibre Content on Compressive and Flexural Properties of Coconut Fibre Reinforced Epoxy Composites

Coconut fibre reinforced polymer composites are gaining popularity in the field of engineering due to the many benefits that come with them such as low cost of production, easy fabrication, enhanced strength compared to other polymer composites. Of late, there has been an increase in the use of composites that are naturally based because they have many benefits. In line with this, the current research is focused on the mechanical properties of coconut fiber reinforced epoxy composites. The effect of the fibre content on the flexural and compressive characteristics of the epoxy composites was investigated. Chemical treatment of the coconut fibres was performed using 50% bleaching concertation. The composites were fabricated in random orientations withe fibre length of 10 mm as recommended by the literature. Scanning Electron Microscopy (SEM) was used to examine the fractured surfaces. The main findings are that the increase in the volume fraction of the coconut fibre in the epoxy composites increases the flexural and compressive strengths. SEM showed that the main failure mechanisms were brittle nature in the epoxy regions and pullout and breakage of fibres in the coconut region

Investigating the lap shear adhesion of coir and glass-fibre reinforced epoxy bonding to mild steel with varying volume fractions

Bonding synthetic fibres to metals to improve strength, durability, and corrosion resistance is a prevalent practise in the automotive, marine, and aerospace industries. Lap shear adhesion, a measurement of the bonding strength between composites and metallic substrates, is essential for structural integrity. The emergence of natural fibre composites as sustainable alternatives to synthetic composites makes it essential to investigate their lap shear behaviour and the effect of fibre volume fraction on composite properties. This research investigates the adhesion behaviour of coir and glass fibre epoxy composites to mild steel. Coir fibres, which are known for their resilience and tenacity, were treated with an alkaline solution to improve their adhesion to the resin. Samples of lap shear adhesion were prepared in accordance with ASTM specifications, and tests were conducted using a tensile machine. Increasing the volume fraction of coir or glass fibres decreased the bond strength, as demonstrated by the results. Due to the fibres’ greater tensile strength and rigidity, glass fibre composites exhibited superior strength. However, under tensile loading conditions, coir fibres exhibited superior adhesion to mild steel surfaces. SEM micrographs confirmed that coir composites exhibit shear failure while glass composites exhibit fibre pull-out behaviour. This study concludes by highlighting the engineering potential of coir fibres, considering their natural properties and cost-effectiveness. It is necessary to further optimise the fiber-matrix interface and comprehend the mechanical behaviour of coir composites in order to maximise their effectiveness. To assure the long-term durability of composite-metal joints, surface preparation, adhesive type, application procedure, and environmental conditions must also be considered. At a content percentage of 10%, glass fibres exhibited 100% higher shear strength compared to coir fibres in epoxy composites. Conversely, coir fibres at 10% content demonstrated approximately 75% greater shear strength than the values obtained with 40% glass fibres. The failure mechanisms observed are delamination or fibre fracture in the bonding area under tensile and shear loading. Increasing the fibre volume fraction reduces bond strength. Factors such as limited space for the matrix, tension concentrations, and the mechanical properties of the fibres contribute to weakened bonds. Glass fibres have better strength and rigidity than coir fibres, affecting load transfer and adhesion. Interfacial bonding is crucial, and maintaining it becomes more difficult with higher fibre volume fractions, resulting in weakened bonds

Survival Rate of Patients with Cardiothoracic Injuries in Road Traffic Accidents, and their Relationship with ISS, GCS and blood transfusions.

Severe thoracic trauma is one of the major causes of injury-related mortality. In the United States, thoracic trauma results in one-fourth of all trauma deaths. Globally, cardiothoracic trauma is also a major contributor to mortality. The most common cardiothoracic injuries include rib fractures, thoracic vertebral fractures, haemothorax, pneumothorax, flail chest, and lung contusions. The purpose of the present study was to determine the survival rate of patients with cardiovascular injuries in road traffic accidents and its relationship with ISS, GCS and blood transfusions at King Khalid Hospital. This study is a useful addition to the literature, as research in this topic is lacking. A total of 189 patients were transported to the hospital with cardiothoracic injuries during the study period. Data was gathered regarding age, gender, nationality, vehicle user type, anatomical region injured, Intensive Care Unit (ICU) admission, Glasgow Coma Scale (GCS), Injury Severity Score (ISS), blood transfusion, treatment and mortality rate. The neurological status was assessed using the GCS score. Injury Severity Scores were calculated to categorize the injury severity. The mean patient age was 31.81 years, with a peak age of between 21–30 years. Males predominated (93.7%) with a male to female ratio of 15:1. Most of the patients were Saudi nationals (61.3%). Overall mortality was 7.9%. Factors that were significantly associated with mortality were head and neck involvement, ICU admission, age (above 60), treatment delivered, and blood transfusions. Cardiothoracic trauma is associated with a high mortality rate, which may depend on the clinical presentation such as GCS, ISS, degree of shock, pattern of injuries, and associated injuries. Immediate management is vital for patients with life-threatening cardiothoracic trauma, as mortality is high if the diagnosis is missed, wrong or left untreated

Enhancing stability and tribological applications using hybrid nanocellulose-copper (II) oxide (CNC-CuO) nanolubricant: An approach towards environmental sustainability

The primary aim of the present study is to assess the stability and efficacy of hybrid nanocellulose (CNC) and copper (II) oxide (CuO) nanoparticles when integrated into engine oil as a lubricant for piston ring-cylinder liner applications. The assessment of system stability was conducted by employing zeta potential measurements. Furthermore, the coefficient of friction and specific wear rate were determined by using hydrodynamic lubrication in circumstances characterised by high speed and low load, as well as boundary lubrication in situations characterised by low speed and high load. The trials used a specially constructed friction and wear testing device miming the contact geometry between piston rings and cylinder liners in an internal combustion engine. Alongside SAE 40 oil, several nanoparticle concentrations (0.1%, 0.3%, 0.5%, 0.7%, and 0.9% added to SAE 40) were examined. The stability of the nanolubricant increased from 0.1% to 0.5% concentration and then declined at 0.9% concentration, according to the zeta potential data. The graph showed that the 0.5% concentration of the nanolubricant had the highest mean zeta potential, indicating exceptional stability. The CNC-CuO nanolubricants showed notable reductions in the friction coefficient regarding tribological performance. The friction coefficient reduced between 33% and 44% in mixed lubrication and 48% and 50% in boundary lubrication. There was a 9–13% decrease in the friction coefficient when hydrodynamic lubrication was used. The CNC-CuO nanolubricant only showed light scuffing, while the SAE 40 sample showed severe exfoliation and scuffing. Wear rates had been enhanced by 33.5%. Overall, the 0.5% concentration of CNC-CuO nanoparticles improved the engine oil's thermophysical properties and performance