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During the last few years, cavities have gained attention in the scramjet community as a promising flame-holding device. The present simulation study attempts to understand the reacting flow cavity characteristics for scramjet flame-holder application. The fuel was injected from upstream of cavity in reacting flow. Effects of cavity length to depth ratio were investigated. As the ratio of length-to-depth (L/D) is 3 or 4, the distribution form of the floor static-pressure of cavity in reacting flow is not consistent with that of cavity in non-reacting flow, even though open cavity flow occurs for the two cases. Open cavity flow occurs for L/D = 5, 6, 7 and 8 in non-reacting flow. Transitional cavity flow occurs for L/D = 5, 6 and 7, and closed cavity flow occurs for L/D = 8 in reacting flow. The flame holding capability of cavity with L/D = 7 is the best among all the cavities by comparison of the recirculation dimensions. Considering the drag of cavity, the cavity with ratio L/D = 5 is the best flame-holder among all cavities. The simulation results demonstrate that the cavity characteristics is different in non-reacting and reacting flows, and the conventional definition of cavity flow characteristics based on non-reacting flows needs to be revised accordingly.

This work is devoted to study the extraction dearomatization of the kerosene fraction using ionic liquids synthesized on the basis of formic acid and morpholine, as well as acetic acid and diethylamine as a selective solvent. The influence of various factors on the selective purification process has been investigated and the conditions for dearomatization of kerosene have been determined. The group hydrocarbon composition of the dearomatized kerosene raffinate samples by ion-liquid extraction was determined by IR and UV spectral analysis.

The performance of correlation between the dielectric parameters of Baobab Oil (BAO) and Mongongo Oil (MGO) is evaluated using Artificial Neural Network (ANN). The BAO and MGO naturally own high Unsaturated Fatty Acids (UFAs) and are highly biodegradable. The temperature studies and dielectric studies are carried out and found that the Natural Esters (NEs) show a reliable performance over mineral oil-based Transformer Oil (TO). Further the endurance test, Partial Discharge Inception Voltage (PDIV) repetition rate and drop after 30 days, dielectric measurements are done as per the standards of IEC (International Electrotechnical Commission) and ASTM (American Society for Testing and Materials). The NEs show stable performance under PDIV and show minimum repetition rate when compared to the TO. The C${}_{10}$H${}_{22}$ or Kerosene (KER) and NEs mixture prove that the NE-based transformer fluids show lesser tendency to hydro peroxidation. The C${}_{10}$H${}_{22}$ acts as a thinning agent and reduces the ageing rate of the NEs, and this leads to slower rate of water saturation. This in turn increases the thermal conductivity of the oil and nearly a 30-days thermal ageing of the oil samples at 90${}^{\circ }$C shows better strength of liquid insulation. The performance of association between the dielectric properties like breakdown voltage and water content, dissipation factor and thermal conductivity prove that the NEs show consistent performance and is a better substitute for the mineral oil-based TO.

Some people think that carbon and sustainable development are not compatible. This textbook shows that carbon dioxide (CO₂) from the air and bio-carbon from biomass are our best allies in the energy transition, towards greater sustainability. We pose the problem of the decarbonation (or decarbonization) of our economy by looking at ways to reduce our dependence on fossil carbon (coal, petroleum, natural gas, bitumen, carbonaceous shales, lignite, peat). The urgent goal is to curb the exponential increase in the concentration of carbon dioxide in the atmosphere and hydrosphere (Figures 1.1 and 1.2) that is directly related to our consumption of fossil carbon for our energy and materials The goal of the Paris agreement (United Nations COP 21, Dec. 12, 2015) of limiting the temperature increase to 1.5 degrees (compared to the pre-industrial era, before 1800) is becoming increasingly unattainable (Intergovermental Panel on Climate Change (IPCC), report of Aug. 6, 2021). On Aug. 9, 2021 Boris Johnson, prime minister of the United Kingdom, declared that coal needs to be consigned to history to limit global warming. CO₂ has an important social cost…