Production of biodiesel from feedstocks with high free fatty acids and its effect on diesel engine performance and emissions

Biodiesel is a fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats. Biodiesel is receiving increasing attention as an alternative, non-toxic, biodegradable and renewable diesel fuel. Many studies have shown that the properties of biodiesel are very close to diesel fuel. Therefore, biodiesel can be used in diesel engines with little or no modification.;Biodiesel is usually produced from food-grade vegetable oils that are more expensive than diesel fuel. Therefore, use of biodiesel produced from food-grade vegetable oil may be limited to cases of severe shortages or emergencies. However, lower cost feedstocks are available. Rendered animal fats and restaurant waste oils are an attractive source to produce biodiesel. The problem with processing rendered fats and oils is that they usually contain large amounts of free fatty acids that cannot be converted to biodiesel using an alkaline catalyst due to the formation of soaps. An alternative way is to use acid catalysts, which are more tolerant of free fatty acids.;The objective of this study was to develop a process to utilize rendered fats, known as yellow grease, as a biodiesel feedstock and to build a pilot plant to implement this process. The pilot plant was successfully constructed and was shown to be capable of processing rendered fats containing 40% free fatty acids.;After preparing a sufficient amount of biodiesel from rendered animal fats and restaurant waste oils, the impact of the biodiesel on diesel engine exhaust emissions and engine performance was evaluated and compared to No. 2 diesel fuel and soybean oil methyl ester. The methyl esters produced from yellow grease gave nearly the same thermal efficiency but higher fuel consumption compared with No. 2 diesel fuel. At the operating condition studied, the biodiesel produced 17.77% and 46.27% lower CO and HC emissions, respectively, than No. 2 diesel fuel. The Bosch Smoke Number for biodiesel from yellow grease was 64.21% less than with No. 2 diesel fuel. The methyl esters had 11.60% higher NOx emissions than the No. 2 diesel fuel. No significant differences were found in the exhaust emissions and engine performance between the biodiesel produced from yellow grease and biodiesel from soybean oil

An Investigation of Geomechanical and Microstructural Properties of Full-Scale Jet Grout Column Constructed in Organic Soil

Jet grouting methods have recently become one of the soil enhancement technologies utilized to provide strength improvement and solve most problems of weak soils. In this study, a full-scale 1 m diameter and 5 m length jet grout (soilcrete) column was constructed in the field with a water-to-cement ratio of 1 and 400 bar pressure injections. A mechanical, physical, and microstructural investigation was performed on jet grout samples taken from six different depths (0.0, 0.5, 1.0, 1.5, 2.0, and 2.5 m) and at the same depth at five different locations, including the center. For normal conditions, samples were prepared for six periods to study dry and saturated conditions. The following tests are performed on each sample: compressive strength index (I-s) in all conditions, water absorption, density, porosity, and interface friction. Additionally, SEM was performed on selected samples to investigate the microstructures of jet grout columns (JGCs). The test results showed that the I-s varies with depth, and within the same depth, the variation is approximately 20%. Other properties also vary with depth and location; for example, the average percentage of water absorption and porosity are considered minimum values at the same location, which are 53 and 30%, respectively. However, the interface friction angle of organic soil-cement grout gains 48 degrees and 10 kPa cohesion. The theoretical part of this study is to predict the diameter of JGC in organic soil

Production of biodiesel from feedstocks with high free fatty acids and its effect on diesel engine performance and emissions

Biodiesel is a fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats. Biodiesel is receiving increasing attention as an alternative, non-toxic, biodegradable and renewable diesel fuel. Many studies have shown that the properties of biodiesel are very close to diesel fuel. Therefore, biodiesel can be used in diesel engines with little or no modification.;Biodiesel is usually produced from food-grade vegetable oils that are more expensive than diesel fuel. Therefore, use of biodiesel produced from food-grade vegetable oil may be limited to cases of severe shortages or emergencies. However, lower cost feedstocks are available. Rendered animal fats and restaurant waste oils are an attractive source to produce biodiesel. The problem with processing rendered fats and oils is that they usually contain large amounts of free fatty acids that cannot be converted to biodiesel using an alkaline catalyst due to the formation of soaps. An alternative way is to use acid catalysts, which are more tolerant of free fatty acids.;The objective of this study was to develop a process to utilize rendered fats, known as yellow grease, as a biodiesel feedstock and to build a pilot plant to implement this process. The pilot plant was successfully constructed and was shown to be capable of processing rendered fats containing 40% free fatty acids.;After preparing a sufficient amount of biodiesel from rendered animal fats and restaurant waste oils, the impact of the biodiesel on diesel engine exhaust emissions and engine performance was evaluated and compared to No. 2 diesel fuel and soybean oil methyl ester. The methyl esters produced from yellow grease gave nearly the same thermal efficiency but higher fuel consumption compared with No. 2 diesel fuel. At the operating condition studied, the biodiesel produced 17.77% and 46.27% lower CO and HC emissions, respectively, than No. 2 diesel fuel. The Bosch Smoke Number for biodiesel from yellow grease was 64.21% less than with No. 2 diesel fuel. The methyl esters had 11.60% higher NOx emissions than the No. 2 diesel fuel. No significant differences were found in the exhaust emissions and engine performance between the biodiesel produced from yellow grease and biodiesel from soybean oil.</p

Physical-mechanical assessment of full-scale soil-cement column constructed in clayey soil

Jet grouting has recently become a soil improvement method used to solve most soil problems. In this study, seven full-scale soil-cement (SC) columns were constructed in clayey soil with different pressure injections (300, 325, 350, 375, 400 bar), jet grout rotations (25, 35, 45 rpm) and a w/c ratio of 1. These parameters were used to examine the geomechanical properties of the SC, such as strength characteristics (UCS and UPV), and SC-soil surface friction. The physical properties were observed by evaluating the water absorption rate, density, and porosity. The diameter variation was analysed to determine the effect of both parameters on SC diameter. The geomechanical properties of the grout columns generally varied with pressure and rotation. The average strength variation for pressure and rotation was 38% and 9%, respectively. The average water a

Assessing the Effect of Seawater and Magnesium Sulfate on the Durability and Strength Properties of Cement-Stabilized Full-Scale Soilcrete Column Constructed in Clayey Soil

Jet grouting techniques have lately become one of the soil enhancement technologies used to increase the strength of poor soils and resolve most of their difficulties. Seven full-scale soilcrete columns (SC) were formed in clayey soil using a one-to-one water-to-cement ratio and different parameters, including five different pressures (30, 32.5, 35, 37.5, and 40 MPa) and three different rotating rates (25, 35, 45 rpm). These metrics were used to assess SC's resistance to chemical attacks [seawater, magnesium sulfate (MgSO4)]. Additionally, it is also working on the strength investigation (unconfined compression test) of samples after 105 days of curing in chemical solutions. Scanning electron microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX) were used to study the microstructural behavior and chemical element distribution of full-scale SCs. As a result, chemical attacks significantly affected upon the SC samples regarding pressure injection and jet grout's rotation parameters. In detail, the seawater solution positively impacted on the strength characteristic of SC specimens compared with the normal environment, which is the average strength has been increased 20%. While, considerable deterioration and deformation were detected in MgSO4 solution, leading to losing the mass and decreasing the strength for both parameters, ranging between -10.2% and -58.8% for mass change and 2.0 and 9.5 MPa for strength, at 105 days curing. SEM and EDX images proved the chemical attacked deteriorations and generation of hydration product with pozzolanic reactions

Physical-mechanical assessment of full-scale soil-cement column constructed in clayey soil (vol 16, e00943, 2022)

No abstract

Numerical and experimental investigations of the effects of the second injection timing and alcohol-gasoline fuel blends on combustion and emissions of an HCCI-DI engine

In this study, experimental and numerical investigations of a homogeneous charge compression ignition (HCCI) combustion engine were performed using alcohol-gasoline fuel blends and two-stage direct injection (TSDI) strategy. A diesel engine was modified to operate as an electronically controlled HCCI-DI engine. TSDI strategy was applied by fixing the first injection timing in intake stroke and varying the second injection timing close to the compression top dead center (TDC). The selected fuels were pure gasoline and four different blends of ethanol and methanol with gasoline, namely E10, E20, M10 and M20. The effects of the second injection timing and alcohol-gasoline fuel blends on the HCCI combustion and emissions were investigated at constant engine speed and high equivalence ratio for the same energy input. CFD simulations were performed using AVL Fire code and CFD results were compared with the experimental results of the HCCI-DI engine. Cylinder gas pressure, rate of heat release (ROHR), maximum cylinder gas temperature, CO and NOx emissions were investigated numerically. Visual information about the in-cylinder temperature distribution and NOx emissions were provided from images taken from the CFD model. It can be understood from both experimental and CFD studies that combustion phase can be most effectively controlled by changing the second fuel injection timing for all fuel blends. Adding alcohol to gasoline helped to decrease NOx emissions while keeping the maximum cylinder gas pressure stable compared to pure gasoline