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Mixing in the combustion chamber is influenced by the velocity distribution of the inlet airflow. Numerical simulations are carried out by using the 3D coupled implicit Reynolds-averaged Navier-Stokes (RANS) equations and the SST k-ω turbulence model. This article compares the flow field characteristics of non-uniform flows with uniform flows. The results show that the penetration depth increases by 22% in the case of a decreasing velocity distribution along the longitudinal direction compared to the increasing velocity condition. The difference in total pressure loss compared to uniform flow is greater than 4%. The mixing coefficient in the cavity is only 81% of uniform flow. The two-hole jet flow approach is able to rapidly reach 90%. The study shows that the non-uniform inlet has a considerable impact on fuel mixing. The high velocity region near the jet hole contributes to the mixing performance of the engine combustion chamber. • A numerical study of the mixing mechanism in supersonic non-uniform flow. • The effects of different flow on the mixing characteristics. • The high-speed region is distributed near the jet is helpful for mixing. • The high velocity flow close to the jet causes the local flow to lift much higher. [ABSTRACT FROM AUTHOR]

This study considers the aircraft configuration impacts of a liquid-hydrogen fuel-cell electric propulsion system when integrated into a single-aisle, transport-class aircraft having comparable performance capability of a Boeing 737-800. This study demonstrates that, given estimated developments in future components and subsystem technologies for a 2050 entry into service date, the design of an aircraft with a liquid-hydrogen fuel-cell-based propulsion system can be feasibly achieved while still meeting mission-level performance characteristics consistent with modern commercial aircraft throughout the anticipated lifetime of the aircraft. Key technologies that enable this are the purposeful integration of fuel cell thermal management, independent inlet compression to pressurize the air input to the fuel cells, and leveraging distributed electric propulsion advantages. Exploration into the impact of fuel cell power loss due to degradation is also presented. The results show a promising configuration of a liquid-hydrogen fuel-cell-based commercial aircraft to serve as a feasible replacement of narrow-body transport aircraft to help meet climate goals set for the aviation industry. [ABSTRACT FROM AUTHOR]

Recently, the theme of the "green transition", in which the economic and commercial prospects of the hydrogen industry play a leading role, in the global energy industry has attracted special attention from business, government and scientific circles in many countries, which is associated with its predicted impact, incl. due to the climate agenda, to the economic, technological and geopolitical redistribution of the energy map of the world at the global and regional levels. Some slowdown in the "green transition" is expected due to the need to overcome the global energy crisis in the next two or three years, which may turn out to be more serious than the crisis of the 1970s of the last century which will require eliminating the shortage of traditional non-renewable energy resources in the near future. Nevertheless, the "green transition", in which hydrogen accents are intensifying, continues to be implemented, which will have a serious impact on the system of international and international economic relations in the world. Thanks to the financial support of the state and business, modern technologies of the entire hydrogen energy chain are actively developing, hydrogen markets are being formed in the conditions of inter-fuel competition, as well as hydrogen energy command centers at the global, regional, country and corporate levels. [ABSTRACT FROM AUTHOR]

Understanding boundary-layer flashback is critical to the design of safe and efficient gas turbines, especially as the addition of highly reactive hydrogen to these devices becomes a prevailing trend for reduction of carbon dioxide emissions. In this work, the boundary-layer flashback of lean hydrogen-air mixtures is studied using large-eddy simulations based on a generic turbulent swirl burner previously investigated experimentally. Simulations at increasing equivalence ratios are used to identify the flashback limits, showing reasonable qualitative agreement with experimental measurements. Flame dynamics during flashback are compared to previous experimental studies, indicating that important physics are captured in the simulations even if the exact flashback limits are not. In particular, a change in the swirl vane angle is shown to dramatically change the flame dynamics, with flame propagation occurring in the direction of swirl at high angles and against the direction of swirl at low angles, consistent with experimental observations. The near-wall nonreacting mean velocity field is shown to be controlled by a temporally stationary flow instability, which is directly responsible for the counterswirl flame flashback exhibited at low swirl angles. Finally, the interaction of local axial flow velocity and flame propagation speed of the leading flame point is investigated with varying swirl angles both before and after the onset of flashback, elucidating the differences in flame dynamics in all four of these cases. In particular, the importance of local flame extinction on flashback limits is emphasized. [ABSTRACT FROM AUTHOR]

Artificial fuels have been researched for more than a decade now in an attempt to find alternative sources of energy. With global climatic conditions rapidly approaching the end of their safe line, an emphasis on escalating the change has been seen in recent times. Synthetic fuels are a diverse group of compounds that can be used as replacements for traditional fuels, such as gasoline and diesel. This paper provides a comprehensive review of synthetic fuels, with a focus on their classification and production processes. The article begins with an in-depth introduction, followed by virtually classifying the major synthetic fuels that are currently produced on an industrial scale. The article further discusses their feedstocks and production processes, along with detailed equations and diagrams to help readers understand the basic science behind synthetic fuels. The environmental impact of these fuels is also explored, along with their respective key players in the industry. By highlighting the benefits and drawbacks of synthetic fuels, this study also aims to facilitate an informed discussion about the future of energy and the role that synthetic fuels may play in reducing our reliance on fossil fuels. [ABSTRACT FROM AUTHOR]

It is becoming increasingly important to develop effective combustion technologies for low calorific industrial gases (LCIG) because of the rising energy demand and environmental issues caused by the extensive use of fossil fuels. In this review, the prospect of these opportunity fuels in China is discussed. Then, the recent fundamental and engineering studies of LCIG combustion are summarized. Specifically, the differences between LCIG and traditional fuels in the composition and fundamental combustion characteristics are described. The state-of-the-art combustion strategies for burning LCIG are reviewed, including porous media combustion, flameless combustion, oxy-fuel combustion, and dual-fuel combustion. The technical challenges and further development needs for efficient LCIG combustion are also discussed. [ABSTRACT FROM AUTHOR]

The paper numerically and experimentally examines a method to reduce combustion length within a Mach 12, shape-transitioning scramjet. As the examined airframe-integrated engine transitions from a rectangular inlet to an elliptical throat, highly three-dimensional flow is delivered to the combustor. Tailored to this nonuniform flowfield, hydrogen fuel is injected at both inlet- and combustor-based stations. The current work shortens the engine combustor and removes a legacy rear-facing step. Computational fluid dynamics guides the length by which the combustor may be reduced while still ensuring sufficient combustion. Experimental validation under shock-tunnel conditions follows. Static pressure and heat transfer measurements throughout the flowpath examined combustion at on-design conditions. Comparisons are made to unfueled and suppressed combustion cases, and efficient combustion is attained with combined inlet- and combustor-based fueling within a combustor reduced in length by 68%. Inlet-only fueling displays similar ignition characteristics to the combined-fueling cases, whereas combustor-only fueling displays marginal pressure and heat transfer increases from suppressed-combustion cases. Measured pressure on the engine nozzle displays greater increases under combined fueling than that which would be obtained through the direct summation of the constituent inlet-only and combustor-only fueled cases, indicating inlet-injected fuel pilots combustion of combustor-injected fuel. [ABSTRACT FROM AUTHOR]

Fuel cell technology holds the combination of benefits, which are barely offered by any other energy generating technology. Because the fuel used in this technology is found in abundance in nature and can also be renewed/sustained. Pakistan is blessed with renewable energy resources which are suitable for fuel cell technology. Therefore, fuel cell technology offers a great opportunity to meet the demand of energy and for the sustainable development of Pakistan. The energy research group at COMSATS Institute of Information Technology (CIIT), Lahore has made efforts to study the technical aspects of fuel cell technology and its commercial benefits. The research group is interested in finding ways and means of generating and storing the energy produced by using fuel cells. In this paper, the research activities on fuel cell technology in Pakistan have been reviewed and it is also discussed how this technology can resolve the current energy crises in Pakistan and can be the source of sustainable energy. It has been also reviewed that the country would greatly benefit from fuel cells and fuel cell hybrid system (environmental friendly technology), which could be the best solution for electricity production as well for automobile industry. [ABSTRACT FROM AUTHOR]

Sorption enhanced steam reforming of ethanol on CuMgAl hybrid materials was studied. A new method of preparation was employed to the ensemble of catalyst and adsorbent for reaction enhancement. These materials were analyzed on their thermal stability and capacity to uptake carbon dioxide for enhanced hydrogen production process. The effects of material nature and operating conditions on the course of reaction were studied. Hydrogen was generated in the temperature range between 473 K and 873 K. The CuMgAl materials show good stability during the reaction process due to the unique layered double hydroxide structure. The hydrogen production through SRE was enhanced by carbon dioxide sorption in the initial transient period, and high purity hydrogen over 90 mol% was obtained. [ABSTRACT FROM AUTHOR]