Liquid Fuels

With the ever rising concern of global warming, carbon
capture is gaining the reputation of one of the most challenging fields of research. A very promising technology to capture CO2 is oxy-combustion. Oxy-combustion offers several advantages over conventional combustion technologies, such as flue gas volume reduction, high combustion efficiency, low fuel consumption and significant reduction in NOx emissions. Liquid fuel is available and it is the most widely used source of energy in the world. Easy handling and transportation, less storage volume and higher flame temperature are some of the features of liquid fuel which give it an upper hand over other sources. In this study, an experimental work on oxygen enriched combustion of ethanol in a vertical reactor by Lacas F. et. al. has been modeled numerically. Non-premixed model using Probability Density Function has been incorporated to simulate the combustion process of ethanol droplets. Predicted combustion characteristics are found to be in good compliance with the experimental data. In addition to this, effects of dilution of carbon-dioxide in oxygen on the flame properties have also been presented. Combustion of ethanol in oxygen- carbon dioxide environment has been compared with that of the conventional air environment.

Globally, renewable energy sees by far the fastest growth, with gasification and electrification remaining the main trends.
As far as the local power utility, Eskom, are concerned they consist of a fleet of thirteen (13) coal fired power stations contributing to approximately 36000MW, a nuclear power plant, four (4) gas or petroleum power stations, two (2) hydro plants and two (2) pump storage facility, collectively contributing to around 41000MW of power generation capacity.
Due to the delays in the planning and decision making process for additional energy resources, the actual reserve margins managed by the local utility were depleted and as a result of unplanned maintenance in 2008 this lead to the need for load shedding across the local utility’s complete network. In addition to this, Eskom did not adhere to the basic law of economics and instead of producing competitive electricity prices  a cumulative increase of 503% from 2008 to 2020 had been observed.
Coal fired pants are expected to remain the dominant source for electricity generation, at least till 2030, when Kusile and Medupi are fully commissioned.
The depletion of national reserve margins sparked the interest into exploring feed-in tariffs (FITs) for renewable energy, but these were later rejected in favour of competitive tenders. The resulting program, now known as the Renewable Energy Independent Power Producer Procurement Program (REIPPPP), constituted of a public-private initiative on a massive and unprecedented scale helped to stabilise power supply and attempted to reduce South Africa’s dependence on coal and diesel, through the introduction of the use of renewable energy resources onto the national grid.  In monetary terms, the Department of Energy reported that the investments into energy, renewables programme has, by 2017, brought $14-billion of foreign direct investment into the country
This report highlights the key area’s of progress within the renewable energy sector in relation to South Africa’s developments as well as the current status of non-renewable energy sources, and electrification.

Results of large-scale experiments on the thermal effect from deflagrations and detonations in rich fuel-air heterogeneous mixtures are presented. Motor fuels (gasoline, kerosene and diesel fuel) were used. The fuel mass in the tests was varied from 0·1 to 100 tonnes. The relationships for the maximum fireball radius, heat effect duration and total emitted energy versus the fuel mass were determined for this kind of process. Direct measurements of the heat flux and integral heat flux were carried out. Comparison with published data for other fuel types is made. The presented results may be used for accident analyses in industry and transport.

In order for saving the constrained resources and preservation of environment, the natural gas is a proven low cost and low emission alternative fuel to petroleum fuels for all types of motor vehicles. It is being widely used throughout the globe. In Malaysia, still millions of vehicles are plying on use of petroleum fuels. These fuels release huge emissions to the environment. Definitely, this adversely affects the natural ecosystem. In this backdrop, a study is felt important to predict the trend of emissions of anti-body gases released by cars in Malaysia for use of liquid fuels and natural gas between 2006 and 2020. The growth of vehicles demand has been considered alongside. The study reveals that current emission levels of different anti-body gases are huge and these can be significantly reduced by converting liquid fuel based engine into the natural gas based engine.

http://www.researchgate.net/publication/215594760_Ergonomic_Evaluation_of_Data_Entry_Task_Performance_Under_The_Influence_of_Noise_and_Task_Structure_-_The_Effect_of_Gender/file/9fcfd513585d0e0a0f.pdf#page=43

Atomization, vaporization, turbulent mixing, and the chemical kinetics of a liquid fuel impact the combustion efficiency, stability, and emissions within IC engines. When fuels with varying physical properties are used in the same fuel injection system, they can exhibit very different atomization, represented by droplet size (SMD) and spray droplet distribution (SDD), which can then potentially influence the flame stability. In the current paper, the effect of the atomization process on flame stability is investigated by using a single nozzle size with three different hydrocarbon fuels, i.e., n-heptane, n-dodecane, and toluene. This study also investigates the flame stability for the same fuels using a unique approach in which nozzle sizes are selectively varied for each fuel to control the atomization process and minimize differences in the spray characteristics. The results show that the atomization process plays a major role in the flame liftoff heights and blowout limits. n-Dodecane, which produces the largest droplets and exhibits the lowest volatility, experiences highest flame liftoff heights and the greatest resistance to flame blowout compared to the other tested fuels. When the atomization process is controlled, more similar liftoff heights and blowout limits for all fuels were observed. The differences in liftoff height was shown to be a result of two-phase (spray) flame speed (i.e., pre-vaporized fuel reactivity (SL), and time scales associated with droplet evaporation). Differences in blowout was shown to be largely tied to fuel volatility, droplet size (i.e., the liquid loading into the flame), and the heat of combustion.

Microwave co-pyrolysis (MCP) of waste cooking oil (WCO) and waste polyolefins (WP) was examined for its potential to convert these wastes into liquid fuel. The influence of performing the pyrolysis process under N2 atmosphere and vacuum environment was investigated with emphasis on the temperature profile, heating rate, and the yield and properties of the liquid oil obtained. Different ratios of WP to WCO (1:2, 1:1.5, 1:1, 1.5:1, and 2:1) were also investigated. MCP performed under vacuum environment recorded higher heating rates (20–24 °C/min) and higher yield of liquid oil (up to 62 wt.%) compared to that performed under N2 atmosphere (18–22 °C/min of heating rate and 24–50 wt.% of liquid oil). The high heating rate resulted in shorter reaction time and lower power consumption, leading to lower energy consumption by the pyrolysis process. The liquid oil comprised C13–C24 hydrocarbons (aliphatics, aromatics) within the hydrocarbon range of diesel fuel. It also showed promising gree...

To investigate the combustion of liquid fuel spray under hot-diluted conditions, a novel type rest rig was designed and constructed at Sharif University of Technology Aerospace Advanced Combustion Laboratory (AACL). By examining flame photographs, as well as CH chemiluminescence images, and in-field temperature measurements, effects of preheating (up to 733k) and dilution of the oxidant (as low as 17%O2) on kerosene spray flame structure have been studied. It was observed that, in conventional combustion, spray flame emerges a double flame structure consisting of an inner and an outer flame front. On the other hand, increasing the coflow temperature or diluting the oxidant, deteriorates the inner flame front, leading to a semi-single flame structure, similar to gaseous flames. It was also noticed that in such hot-diluted environment the reaction volume is reduced, the temperature field has become more homogeneous, the peak temperature is limited to less than 1500k, and temperature fluctuations have significantly decreased, which resembles MILD combustion regime conditions, corroborating its viability for liquid fuels.

Liquid fuels have different physical and chemical properties which can affect the atomization, evaporation and mixing processes inside heat engines, including turbine and reciprocating internal combustion engines. In this work, the relationship between the fuel’s properties and its ignition/flame stability is investigated. A spray burner was designed and manufactured to simulate the mixing dynamics experienced in a turbine engine combustor capable of delivering high fuel and air co-flow rates. The flame behavior and stability have been studied by measuring the flame liftoff heights and blowout limits for different single component fuels at different fuel and air flow conditions. In addition, a Fuel Ignition Tester (FIT) was used to investigate the impact of volatility and local enrichment on ignition delay. Results indicate a strong influence of fuel volatility and atomization on the flame stability. The less volatile/heavier fuels have higher liftoff heights, while the fuels with smaller droplet sizes and higher volatility blowout easier than less volatile fuels and those which atomize into larger droplets. In the FIT, it was noticed that the local equivalence ratio defined by the fuels volatility has more effect on the ignition delay than the global air fuel ratio. As a result, ndodecane ignites faster than n-heptane, despite the having a lower measured global equivalence ratio.

With the aim of developing and testing the model of liquid fuel ignition by flame heat flux a simplified approach is presented to evaluate the ignition conditions on the basis only of well-known fuel characteristics. The case of a sufficient size of heat source which enables boundary effects to be ignored and the case of local ignition are considered. In accordance with the presented model, critical parameters of ignition (heat flux power, exposure time, heat source size) of typical heavy fuels are determined. Direct experimental validation for the model is presented. Experimentally-determined critical parameters for diesel fuel are in a good agreement with calculated results.

Oil from the pyrolysis of biomass typically consists of two different layers defined as the aqueous and organic phases. The objective of this study was to determine the yield of liquid fuel that can be produced from the aqueous phase using a catalytic conversion. The process was supported by two different HZSM-5 catalysts with temperatures set at 405, 455, 505, and 555 °C. The oils obtained were then analyzed using Karl Fischer titration, FTIR spectroscopy, GC/MS, TGA, and CHNS/O analysis. The results showed that the oil yields obtained from catalytic cracking of the aqueous phase ranged from 4 to 9.16 wt % depending on the catalyst type and temperature. The optimum performance of deoxygenation activity was obtained with the HZSM-5/50 catalyst at a temperature of 555 °C. The oil produced under the optimum conditions was dominated by aromatics and phenols and had an HHV of 38.44 MJ/kg. © 2014 American Chemical Society.

http://pubs.acs.org/doi/pdfplus/10.1021/ef5003952   
http://umexpert.um.edu.my/file/publication/00009619_106428.pdf

Microwave co-pyrolysis (MCP) of waste cooking oil (WCO) and waste polyolefins (WP) was examined for its
potential to convert these wastes into liquid fuel. The influence of performing the pyrolysis process under N2
atmosphere and vacuum environment was investigated with emphasis on the temperature profile, heating rate,
and the yield and properties of the liquid oil obtained. Different ratios of WP to WCO (1:2, 1:1.5, 1:1, 1.5:1, and
2:1) were also investigated. MCP performed under vacuum environment recorded higher heating rates
(20–24 °C/min) and higher yield of liquid oil (up to 62 wt.%) compared to that performed under N2 atmosphere
(18–22 °C/min of heating rate and 24–50 wt.% of liquid oil). The high heating rate resulted in shorter reaction
time and lower power consumption, leading to lower energy consumption by the pyrolysis process. The liquid oil
comprised C13–C24 hydrocarbons (aliphatics, aromatics) within the hydrocarbon range of diesel fuel. It also showed promising green properties comprising low nitrogen and oxygen content, and free of sulphur. Combined with the detection of high energy content (42–49 MJ/kg) and low moisture content (< 1 wt.%), the liquid oil shows great potential to be used as a fuel. Our results show that MCP performed under vacuum environment
shows potential as a promising pyrolysis approach with improved heating performance and production of hydrocarbon fuel with desirable fuel properties.