Search results for "Fuel Technology"
showing 10 items of 323 documents
An analysis methodology to evaluate the contribution to electrical security given by bare buried conductors in a system of intertied earthing grids
2004
The paper presents an analysis methodology for a single-line-to-ground fault, occurring at a secondary MV/LV substation in a power network formed by a HV/MV station, feeding, through a MV tri-phase cable line, N MV/LV substations whose earth electrodes are interconnected by bare buried conductors. In the preliminary explanation of the methodology, earth buried conductors are studied in their double function of earth electrodes and connection elements between earthing grids, both in absence and in presence of other interfering conductors. Subsequently analyzed is, with a distributed parameters approach, the system constituted by an earth buried conductor and a MV tri-phase cable line. The eq…
Effect of transition metals and homogeneous hydrogen producers in the hydrothermal liquefaction of sewage sludge
2022
Hydrothermal liquefaction (HTL) of sewage sludge (SS) was performed in the presence of metallic Zn, Fe and Ni to investigate their effect on the performances of the process in terms of product yields and quality. Experiments were performed in subcritical water at 350 ◦C for 10 min using each metal individually and in the presence of homogenous hydrogen producers like formic acid (FA) and KOH. Interesting results were obtained with Zn that when used alone or in the presence of KOH, increased the cumulative biocrude (BC) yields and resulted in energy recoveries (ER) higher than 100% with respect to initial energy content of the biomass, thus indicating that HTL of SS is globally endothermic. …
Fabrication and characterization of nanostructured Ni–IrO2 electrodes for water electrolysis
2014
Abstract Nanostructured Ni–IrO2 electrodes were fabricated by electrodeposition in a two-step procedure: first arrays of nickel nanowires (NWs) were electrodeposited within pores of polycarbonate (PC) membranes, then iridium oxide nanoparticles were deposited on the Ni metal after membrane dissolution, for improving the catalytic activity. The aim was to compare performance of these electrodes with traditional ones consisting of Ni film. Different methods of deposition of the IrO2 electrocatalyst were investigated and the effect on electrodes stability and activity is discussed. Despite a low coverage of Ni NWs by the electrocatalyst, results indicate a faster kinetics of O2 evolution in 1 …
Reactivity of cellulose during hydrothermal carbonization of lignocellulosic biomass
2020
Abstract Hydrothermal carbonization (HTC) of pure cellulose (CE) and birchwood (BW) samples was carried out at temperatures between 160 and 280 °C, 0.5 h residence time and biomass-to-water ratio 1:5, to investigate the reactivity of cellulose in lignocellulosic biomass. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) showed that the CE samples remained unaltered at temperatures up to 220 °C, but were significantly decomposed at 230 °C producing a thermal recalcitrant aromatic and high energy-dense material. FTIR showed that dehydration and aromatization reactions occurred at temperature equal or higher than 230 °C for the CE samples while a similar incre…
Modeling of the catalytic effects of potassium and calcium on spruce wood gasification in CO2
2016
Abstract Using previously reported thermogravimetric analysis measurements, the effects of calcium and potassium on the char gasification rate of spruce wood were modeled. Spruce wood was leached of inorganic ash elements and doped with measured amounts of potassium and calcium. The wood was gasified in an isothermal thermogravimetric analysis device in CO 2 where the devolatilization of the wood, char formation and char gasification all occurred inside the preheated reactor. A new method for separating the effects of devolatilization and char gasification is presented. Kinetic models were evaluated for their ability to describe the observed catalytic effects of potassium and calcium on the…
The effect of feedstock origin and temperature on the structure and reactivity of char from pyrolysis at 1300–2800 °C
2018
This study reports the effect of feedstock origin, residence time, and heat treatment temperature on CO2 and O2 reactivities, nanostructure and carbon chemistry of chars prepared at 1300, 1600, 2400, and 2800 °C in a slow pyrolysis reactor. The structure of char was characterized by transmission electron microscopy and Raman spectroscopy. The CO2 and O2 reactivity of char was investigated by thermogravimetric analysis. Results showed that the ash composition and residence time influence the char reactivity less than the heat treatment temperature. The heat treatment temperature and co-pyrolysis of pinewood char with biooil decreased the CO2 reactivity, approaching that of metallurgical coke…
An experimental investigation on the long-term compatibility of preheated crude palm oil in a large compression ignition diesel engine
2018
An experimental study was carried out on a large stationary compression ignition engine to evaluate the long-term compatibility and durability issues associated with the use of crude palm oil as fuel. Two different preheating temperatures (60 and 80 °C) were adopted to assess the potential improvements related to lower fuel viscosity. The results obtained, in terms of in-cylinder carbon deposits and engine wear, were compared with the results obtained using ordinary diesel fuel. For each fuel and preheating temperature, the engine was operated for 300 consecutive h, during which several engine lubricant samples were collected and analysed to determine soot and fuel contaminations, viscosity…
Upgrade of citrus waste as a biofuel via slow pyrolysis
2015
Abstract Slow pyrolysis (200–650 °C) experiments on citrus residues (orange peel waste “OP” and lemon peel waste “LP”) were carried out in lab scale fixed bed batch reactor. Bio-oil and bio-char obtained by thermal degradation are more stable, more homogeneous and higher energy content fuels when compared to the parent feedstock. Thermogravimetric analysis (TGA) showed higher stability of LP waste, which appears related to the higher lignin content . Mass and energy yields of solid and liquid products (i.e., char and oil) were measured to determine the effects of peak temperature on feedstock. A linear correlation between Gross Calorific Value (GCV), peak temperatures and mass loss (ML) all…
A salt-induced mechanism for the swelling of black liquor droplet during devolatilization
2017
Abstract Black liquor (BL) from the pulp and paper industry is a significant bioenergy source. Swelling of BL droplet during the pyrolysis stage of combustion and gasification is a profound phenomenon affecting various boiler processes. However, the mechanism for droplet swelling has remains a puzzle due to an insufficient understanding of the formation of the plastic droplet at the pyrolysis stage of the thermal conversion. Thermogravimetric studies with model aliphatic carboxylates unraveled the melting and decomposition behavior of the complex mixture of BL salts during pyrolysis, indicating that the melting of salts forming a liquid state may be the primary cause for the development of …
Characterization and reactivity of charcoal from high temperature pyrolysis (800-1600°C)
2019
This study presents the effect of wood origin and heat treatment temperature on the CO2 reactivity, nanostructure and carbon chemistry of chars prepared at 800, 1200, and 1600 °C in slow pyrolysis reactors. The structure of charcoal was characterized by transmission electron microscopy, Raman spectroscopy, mercury intrusion porosimetry and N2 adsorption. The CO2 reactivity of char was investigated by thermogravimetric analysis. Results showed that spruce and oak chars have similar reactivity at all heat treatment temperatures. The oak char prepared at 1600 °C contained long and flat graphene layers and interplanar distance that is similar to graphite and thus, was more ordered t…