Browse Topic: Gases

Items (3,874)
In early of 2023 the European Union began the process of banning the so-called Per- and polyfluoroalkyl substances, with a total elimination forecast for 2035. Currently, the refrigerant gas used by automakers is the R1234yf, a substitute for the R134a as a refrigerant with zero degree of ozone layer destruction, developed to meet the European directive 2006/40/EC that came into force in 2011. It requires all new car platforms for sale on the continent to use a refrigerant in their air-conditioning system with a Global Warming Potential below 150. The alternatives studies for the replacement of R1234yf are R744 (CO2) and R290 (Propane). The first is characterized by being a non-flammable gas and has a working pressure of 6 to 12 times higher than the current one. The second has the characteristic of having working pressure similar to R1234yf, but it is a highly flammable gas. This work focuses on the analysis of the two alternative gases to R1234yf, exploring their characteristics
Ariza, Valquíria RezendeErberelli, Diego PivattoSilva, Pedro Henrique Moraes daMiyauchi, Edison Tsutomu
This paper focuses on the performance of the high-pressure oxygen cylinder oxygen supplemental system in the lavatory of civil aircraft. Due to the potential safety hazards of chemical oxygen generators in the lavatory, high-pressure gaseous oxygen cylinders are used instead. Through theoretical and study, the influence of the orifice on the oxygen flow rate is thoroughly investigated. Based on relevant principles, the calculation method of the gas flow characteristics in the orifice is determined. Considering the high initial pressure of the oxygen cylinder, the supersonic flow condition within approximately 20 minutes is mainly considered. The Simulink is used to simulate the system flow rate under different temperatures during cabin depressurization. Experimental verification shows that the oxygen flow rate under different temperatures meets the minimum oxygen demand, and the simulation results are highly consistent with the experimental results, indicating that the simulation
Wan, ShutingLei, MingjunYu, Xiaoying
In today’s medical equipment market, reliability is not a luxury — it is a necessity. Every adjustment, every movement, and every interaction with the equipment must be performed flawlessly to ensure patient safety, caregiver efficiency, and long-term service life. Behind this design and precision are highly engineered motion control components, such as gas springs, electric linear actuators, and dampers, that ensure safe, ergonomic operation of medical equipment across a wide range of healthcare applications.
NASA’s Glenn Research Center has developed a method of using entangled-photon pairs to produce highly secure mobile communications that require mere milliwatts of power. Conventional gas Argon-ion laser sources are too large, expensive, and power-intensive to use in portable applications. By contrast, Glenn’s patented optical quantum communication method produces entangled-photon pairs approximately a million times more efficiently than conventional sources, in a system that is small and light enough to be portable.
Hydrogen is a clean-burning fuel that could help to replace fossil fuels in transportation, the chemicals industry, and many other sectors. However, hydrogen is also an explosive gas, so it is essential to have safety systems that can reliably detect leaks in a variety of circumstances.
Combustion engines operating on a hydrogen-argon power cycle (H-APC) offer potential for superior thermal efficiency with true zero exhaust emissions. The high specific heat ratio of argon allows extrapolation of the theoretical efficiency of the Otto cycle to almost 90%. However, this potential is significantly constrained by challenges in combustion control, excessive thermal loading, and system integration, particularly regarding argon recovery. This study investigates these trade-offs, within the context of real-world engine-based peaking power plants. An experimentally validated 1D-simulation model of a prototype Wärtsilä 20 DF engine serves as reference for analysis of a retrofit incorporating a closed-loop argon cycle, with dedicated H₂ and O2 injectors, a water condenser and water separator. Engine performance is evaluated at reference operating point of 75% load, considering pre-ignition, peak pressure and exhaust temperature constraints, condenser limitations, and impurity
Ahammed, SajidAhmad, ZeeshanMahmoudzadeh Andwari, AminKakoee, AlirezaHyvonen, JariMikulski, Maciej
This paper deals with the hydrogen-to-helium jets comparison within the framework of the assessment of helium as a potential hydrogen surrogate. The comparison is centred on the assessment of the combined action of pressure ratio with gas properties on the dynamics of the jet exiting an outward-opening injector. The shots are performed at injection pressures and backpressures ranging from 21 to 36 bar and from 1.2 to 5 bar, respectively. The Schlieren technique is deployed to capture the jets images. The study demonstrates that at certain pressure ratios helium is an appealing solution bridging the lab safety with fidelity to hydrogen-like jet behaviour. Decreasing pressure ratio minimizes the hydrogen-to-helium difference in axial penetration and area, enabling helium to yield a hydrogen-like development. The findings underscore the impact of the pressure ratio on how the gas properties, such as density and diffusivity, dictate the evolution of the axial propagation and area
Coratella, CarloTinchon, AlexisHespel, CamilleDober, GavinFoucher, Fabrice
Imagine a robot that can walk, without electronics, and only with the addition of a cartridge of compressed gas, right off the 3D printer. It can also be printed in one go, from one material.
In order to comply with increasingly stringent emission regulations and ensure clean air, wall-flow particulate filters are predominantly used in exhaust gas aftertreatment systems of combustion engines to remove reactive soot and inert ash particles from exhaust gases. These filters consist of parallel porous channels with alternately closed ends, effectively separating particles by forming a layer on the filter surface. However, the accumulated particulate layer increases the pressure drop across the filter, requiring periodic filter regeneration. During regeneration, soot oxidation breaks up the particulate layer, while resuspension and transport of individual agglomerates can occur. These phenomena are influenced by gas temperature and velocity, as well as by the dispersity and reactivity of the soot particles. Renewable and biomass based fuels can produce different types of soot with different reactivities and dispersities. Therefore, this study focuses on the influences of soot
Desens, OleHagen, Fabian P.Meyer, JörgDittler, Achim
A long-lasting, 3D-printed, adhesive-free wearable provides a more comprehensive picture of a user’s physiological state. The device, which measures water vapor and skin emissions of gases, continuously tracks and logs physiological data associated with dehydration, metabolic shifts, and stress levels.
As a carbon-free molecule, ammonia is more and more considered as a relevant fuel for long distance and off-road applications. However, this gas has different combustion characteristics compared to conventional fuels, challenging the suitability of lubricants to such engines. In this work, the evolution of lubricants under conditions mimicking ammonia combustion was assessed. Mineral and polyester lubricant base oils were exposed to oxygen, nitrogen oxides, and ammonia in a pressurized reactor under stirring. Oil aliquots were sampled at regular intervals, and characterized using Fourier Transform Infrared Spectroscopy (FTIR), viscosity and total oxygen and nitrogen contents measurements. Exposure to air containing nitrogen oxides resulted in quicker accumulation of oxidation products compared to neat air, for both the mineral and complex polyester base oil. Besides, exposure to gaseous ammonia in air resulted in a slower oxidation rate for both oils, compared to neat air. A global
Doncoeur, CaroleGiarracca, LuciaCologon, PerrineRousselle, Christine
The working conditions of combustion systems have been going extreme under the desire of human beings exploring the unknown. Cold environments can be a significant impact on the spraying of fuel not only by changing the fuel properties including viscosity and surface tension, but also by freezing the parts. In the present study, methanol spray from a commercial injector is studied via high-speed imaging, with the liquid fuel being frozen to sub-zero degrees at the injector tip. It is observed that water components from the environment will freeze at the injector tip, creating crystal structures on the surface. During the injection, the ice components will be flushed by the liquid, and the spray morphology of the starting cycle will be strongly altered, resulting in wider spray angles, much shorter penetrations, and particle structures can be observed in the downstream of the flow field. The results of the experiment provide a clear view and quantified evaluation of the freezing impact
Zeng, TingxiWang, ShangningZhang, YijiaHung, DavidXu, Min
This study presents a novel biomimetic flow-field concept that integrates a triply periodic minimal surface (TPMS) porous architectures with a hierarchical leaf-vein-inspired distribution zone, fabricated through 3D printing. By mimicking natural transport systems, the proposed design enhances oxygen delivery and water removal in proton exchange membrane fuel cells (PEMFCs). The results showed that I-FF and G-FF significantly improved mass transport and water management compared to conventional CPFF. The integrated design I-FF-LDZ achieves up to 32% improvement in power density at 1.85 A/cm2@0.4 V and delays the onset of mass transport losses. The study also reveals that optimizing the volume fraction Vf significantly affects gas penetration, with lower Vf (30%) improving performance in the mass-limited region. These findings underscore the promise of nature-inspired, 3D-printed flow-field architectures in overcoming key transport limitations and advancing the scalability of next
Ho-Van, PhucLim, Ocktaeck
The race is on for leadership in cislunar space, considered a gateway to the future of space exploration. Yet operating in this domain introduces unique challenges for propulsion systems. In contrast to low-Earth orbit (LEO), the cislunar environment requires higher precision propulsion solutions; these are necessary to enable rapid and accurate maneuvering of spacecraft and long-term sustainability. Propellants like hydrazine and nitrogen tetroxide offer the high energy density required for cislunar missions, but they must be handled very differently from the inert, non-reactive gases at play in LEO systems.
The hot surface-assisted spark ignition (HSASI) pre-chamber spark plug, which was developed at the Karlsruhe University of Applied Sciences, increases the dilution limit with excess air and the tolerance to residual gas in the pre-chamber compared to a conventional passive pre-chamber spark plug. In this study, the conventional glow plug which is integrated in the pre-chamber of the HSASI pre-chamber spark plug was replaced by a pressure sensor glow plug (PSG) from BERU. This allows for a detailed combustion analysis in the pre-chamber. The signal of the PSG was validated with a piezoelectric cylinder pressure sensor and a method to analyse the pre-chamber heat release was introduced. Experimental investigations were carried out on a single-cylinder gasoline engine. A series of operating points diluted with excess air and a variation in load were conducted. The gas flow rate through the orifices of the pre-chamber was calculated from the pressure difference between the pre-chamber and
Holzberger, SaschaKettner, MauriceKirchberger, Roland
The relation between the multiple auto-ignition in the premixed charge with fuel concentration distribution and associated pressure wave are numerically investigated. This study assumes that the auto-ignition phenomenon in the end-gas of PCCI combustion, a next-generation combustion method which is expected to achieve both low fuel consumption and low emissions at a high level. Detailed numerical analysis considering the elementary chemical reactions of the compressible reacting fluid flow described in the one-dimensional coordinate system with high spatial and time resolution was performed to clarify the detailed phenomena of the onset of the multiple auto-ignition and the pressure wave propagation in the gas.
Iizumi, KotaYoshida, Kenji
In response to the evolving landscape of exhaust gas regulations for small powertrains, reducing NOx emission is increasingly important. This study deeply investigated the feasibility of a NOx storage catalyst (NSC) containing cerium oxide (CeO2) and barium oxide (BaO) for reducing NOx emission. The key functions, NOx storage and reduction performances were evaluated, and deterioration mechanisms were explored through performance evaluations and physical property analyses. The findings revealed a strong correlation between the size of CeO2 crystals and NOx storage performance at low temperature, such as those encountered during city driving conditions. Conversely, at high temperature, such as those during highway driving conditions, NOx storage performance correlated well with sulfur deposition, suggesting that the formation of barium sulfate (BaSO4) contributes to the deactivation. This experiment also showed a strong correlation between NOx reduction performance and BaSO4 formation
Nakano, FumiyaKoito, Yusuke
The interplay of electrochemistry, two-phase flow, and heat transfer generates complex transport phenomena within the porous materials of fuel cells that are not yet fully understood. This lack of comprehensive understanding complicates the modeling of liquid water transport, which is critical because the hydration of the polymer electrolyte membrane significantly impacts the cell performance. The liquid water transport mechanisms in porous media can be explained by capillary force, hydraulic permeation and gravity effects, as well as water condensation and evaporation. In general, the liquid water transport is mainly driven by the capillary force, while body forces, such as gravity, do not significantly affect its momentum. Due to limited experimental data on capillary pressure and saturation in gas diffusion media, the Leverett approach has been widely used for modeling liquid water transport in PEMFCs. The Leverett approach is a polynomial fitting of capillary pressure data for
Marra, CarmineCroci, FedericoFontanesi, StefanoBerni, FabioD'Adamo, Alessandro
Automotive industry is growing rapidly with innovations leading to increase in new features and improving the Quality of vehicles. These new components are developed with the available design standards across global OEMs. This Quality research paper aims to address the need of revision of design standards due to environmental factors prevailing in India. With the increase towards autonomous mobility, the number of electronics is also increasing, and this involves hardware & software evaluation. The hardware testing is a point of concern due to increase in the failure rate from the markets. Environment changes are very much evident with the growing economies and OEMs are developing the components with innovation, but if the basic design standards are not revised in parallel with the changing environment, the issues will continue to trouble the end customers. The failed cases data received from across the country was analyzed and observed that the cases are majorly reported from urban
Marwah, RamnikPyasi, PraveenBindra, RiteshGarg, Vipin
In order to comply with the tightening of global regulations on automobile exhaust gas, further improvements to exhaust gas control catalysts and upgrades to on-board diagnostics (OBD) systems must be made. Currently, oxygen storage capacity (OSC) is monitored by front and rear sensors before and after the catalyst, and deterioration is judged by a decrease in OSC, but it is possible that catalyst deterioration may cause the rear sensor to detect gas that has not been sufficiently purified. It is important to observe the activity changes when the catalyst deteriorates in more detail and to gain a deeper understanding of the catalyst mechanism in order to create guidelines for future catalyst development. In this study, we used a μ-TG (micro thermogravimetric balance) to analyze in detail how differences in design parameters such as the type of precious metal, detection temperature, and mileage (degree of deterioration) affect the OSC rate in addition to the OSC of the ceria-based
Hamada, ShotaUegaki, ShinyaTanabe, HidetakaNakayama, TomohitoJinjo, ItsukiKurono, SeitaOishi, ShunsukeNarita, KeiichiOnishi, TetsuroYasuda, KazuyaMatsumura, DaijuTanaka, Hirohisa
Depletion of petroleum crude oil and its environmental impacts challenge future generations. Vegetable oils provide a sustainable alternative with benefits like anti-wear properties, biodegradability, and renewability. Kusum oil's ability to lower carbon emissions significantly and promote sustainable industrial practices highlights its potential as a viable green alternative. This research paper presents a comprehensive and comparative analysis of a sustainable, environmentally friendly bio-lubricant and nonedible vegetable oil like Kusum oil. Bio-lubricant is produced by transesterification followed by epoxidation, which is known as epoxidized kusum oil lubricant or dehydrated kusum oil (DKO). The process of epoxidation significantly enhances the properties of Kusum oil, making it a promising alternative to conventional lubricants. It is compared with a widely used conventional mineral oil lubricant like SAE10W40. DKO exhibits comparable density, viscosity index, pour point, and
Prabhakaran, JPali, Harveer SinghSingh, Nishant K.
The paper presents novel studies on the electrical-to-thermal energy deposition to gas at different phases of a spark. The experiments utilized a 10.9 milliliter custom-built spark calorimeter. The energy transfer efficiencies across spark phases—breakdown+arc, and glow are quantified, emphasizing their importances in ensuring robust ignition. An AC capacitive ignition system was considered in the experiments. The spark plugs used in the experiments were of dual-nickel standard J-gap design of a fixed electrode gap. Test results show the breakdown+arc phases are highly efficient in converting electrical to thermal energy, crucial for ignition. The glow phase, offering control flexibility, is found to be less effective in energy transfer from spark to gas. In addition, a maximum threshold for both glow current and duration is found. Exceeding the threshold reduces the net energy deposition to the gas, indicating an increase in thermal energy losses, primarily to the spark plug
Saha, AnupamTunestal, PerAengeby, JakobAndersson, Oivind
Plasma is a state of matter, like a solid, liquid, or gas. When sufficient energy is applied to a gas, it becomes ionized, transitioning into the plasma state. With precise application and control, plasma can alter surface properties of a metal or plastic part without compromising the underlying material.
Copper Antimony Sulfide (CuSbS2) is a promising ternary semiconductor for use as an absorber layer in third-generation thin film heterojunction solar cells. This newly developed optoelectronic material offers a viable alternative to cadmium telluride (CdTe) and copper indium gallium di-selenide (Cu(In,Ga)Se2) due to its composition of inexpensive, readily available, and non-toxic elements. These films were successfully produced at an optimal substrate temperature of 533 K using the conventional spray technique. X-ray diffraction and Raman studies confirm that the films exhibit a chalcostibite structure. Characterization studies reveal that the films possess lattice parameters of a = 0.60 nm, b = 0.38 nm, and c = 1.45 nm, with an absorption coefficient of 105 cm-1 and a band gap of 1.50 eV. Notably, the films exhibit p-type conductivity. All of these studies confirm that CuSbS2 is an excellent choice for the absorber layer in solar cell applications. An attempt was made in this study to
Kumar, YB KishoreYb, KiranTarigonda, HariprasadReddy M, Surya Sekhar
NASA's Cryogenic Flux Capacitor (CFC) capitalizes on the energy storage capacity of liquefied gases. By exploiting a unique attribute of nano-porous materials, aerogel in this case, fluid commodities such as oxygen, hydrogen, methane, etc. can be stored in a molecular surface-adsorbed state. This cryogenic fluid can be stored at low to moderate pressure densities, on par with liquid, and then quickly converted to a gas, when the need arises. This solution reduces both safety-related logistics issues and the limitations of complex storage systems.
Hydropneumatic Struts (HPS) are widely implemented in automobile, aerospace, and construction industries, mainly for the purpose of vibration and shock absorption. The HPS design with integrated gas–oil chamber is relatively more compact and robust, while mixing gas and oil inside the HPS generates gas–oil emulsion and more nonlinearities. This study formulated a nonlinear analytical model of the compact HPS with gas–oil emulsion, considering the real gas law and pressure-dependent LuGre friction model. The polytropic version of the van der Waals (vdW) method for real gas is applied to represent the thermodynamic behavior of nitrogen. The experimental data were collected at a near temperature of 30°C with three charging pressures under excitations in the frequency range of 0.5–6 Hz, considering two flow connection configurations between chambers as one- and two-bleed orifice. The nonlinear behavior of the gas volume fraction of the emulsion was identified based on peak strut velocity
Seifi, AbolfazlYao, YumengYin, YumingMoore, MasihRakheja, Subhash
LIDAR-based autonomous mobile robots (AMRs) are gradually being used for gas detection in industries. They detect tiny changes in the composition of the environment in indoor areas that is too risky for humans, making it ideal for the detection of gases. This current work focusses on the basic aspect of gas detection and avoiding unwanted accidents in industrial sectors by using an AMR with LIDAR sensor capable of autonomous navigation and MQ2 a gas detection sensor for identifying the leakages including toxic and explosive gases, and can alert the necessary personnel in real-time by using simultaneous localization and mapping (SLAM) algorithm and gas distribution mapping (GDM). GDM in accordance with SLAM algorithm directs the robot towards the leakage point immediately thereby avoiding accidents. Raspberry Pi 4 is used for efficient data processing and hardware part accomplished with PGM45775 DC motor for movements with 2D LIDAR allowing 360° mapping. The adoption of LIDAR-based AMRs
Feroz Ali, L.Madhankumar, S.Hariush, V.C.Jahath Pranav, R.Jayadeep, J.Jeffrey, S.
Magnesium is the lightest material than aluminium and has a better specific strength, which is utilized for weight management applications. This research developed the magnesium (Mg) matrix with 0.1, 0.2, 0.3, and 0.5 percentages in weight (wt%) of zirconium (Zr) particles (grain refinement agent) via the squeeze cast technique. The argon inert gas is limit oxidation during the melting of Mg. The influence of Zr on the functional properties of Mg is studied and related to monolithic Mg without the Zr phase. The microstructural analysis provides the Zr particles are dispersed uniformly in the Mg matrix and exposed to superior mechanical properties. The Mg processed with 0.5 wt% of Zr offered maximum hardness, ultimate tensile strength, and elongation percentage, which are 53, 48.8, and 43.5 % better than the values of monolithic Mg. Besides, the optimum Mg refining with 0.5 wt% Zr microstructure is detailed with EDS and conforms to the contribution of Zr. This is used for automotive
Venkatesh, R.Manivannan, S.Das, A. DanielMohanavel, VinayagamSoudagar, Manzoore Elahi Mohammad
This research investigates the impact of friction stir welding (FSW) used to join micro-alloyed steel, on the material and its mechanical characteristics. FSW increases the metallurgical and mechanical qualities of joints made from micro-alloyed steel. However, Friction Stir Welding has produced only modest improvements in connecting steels. Automobile chassis, offshore platforms, oil and gas pipelines, mining, shipbuilding and railroad carriages, pressure vessels, bridges, and storage tanks are just some of the many places and find micro-alloyed steels employed. Frictional heat and tool movement over the joint cause micro defects occurred. Tungsten carbide tools are used in this investigation. Welding shares the same process characteristics, such as the tool's rotating speed (900 rpm) and axial force (10 kN). The table's traverse speed options are available, including 50 mm/min, 60 mm/min, and 70 mm/min. Vickers microhardness testing machines and tensile testing machines are used to
Rajan, C. SakthiKumar, N. MathanKumar, K. VetrivelKannan, S.Soundararajan, S.
Recently, there has been a growing emphasis on Thermal Management Systems (TMS) for Lithium-ion battery packs due to safety concerns related to fire risks when temperatures exceed operating limits. Elevated temperatures accelerate electrochemical reactions, leading to cell degradation and reduced electronic system performance. These conditions can cause localized hotspots and hinder heat dissipation, increasing the risk of thermal runaway due to high temperatures, flammable gases, and heat-producing reactions. To tackle these issues, many automotive manufacturers employ indirect liquid cooling techniques to maintain battery pack and electronic system temperatures within safe limits. Engineered nanofluids, particularly those containing multi-nanoparticles dispersed in water and ethylene glycol, are being explored to enhance electrical safety in case of accidental exposure to electrical systems in EVs. This paper focuses on the experimental characterization of nanofluid containing
Nahalde, SujayHonrao, GauravMore, Hemant
R-1234yf is used in almost every new car sold in the U.S., but the EU is discussing a ban and the industry is investigating alternatives like CO2 and propane. According to its manufacturer, Chemours, use of R-1234yf has grown so much since the refrigerant replaced the long-established R-134a that it's now used in 95% of new cars sold in the U.S. An estimated 220 million cars on global roads are also using it. The problem with R-134a, which came in cars and trucks in the 1990s, is that it's a gas with “a global warming potential (GWP) that is 1,430 times that of CO2,” according to the EPA. Since 2017, EU legislation has banned the use of any refrigerant in new vehicles with a GWP higher than 150. That rule doomed R-134a but opened the door for R-1234yf, which has a GWP of only four. The EU is currently revisiting R-1234yf emissions rules and may ban the substance in a few years. In the U.S., the EPA stands by its use.
Motavalli, Jim
A major challenge for auto industries is reducing NOx and other exhaust gas emissions to meet stringent Euro 7 emission regulations. A urea Selective Catalyst Reduction (SCR) after-treatment system (ATS) commonly uses upstream urea water injection to reduce NOx from the engine exhaust gas. The NOx emission conversion rate in ATSs is high for high exhaust gas temperatures but substantially low for temperatures below 200°C. This study aims to improve the NOx conversion rate using urea pulse injection in a mass-production 2.2 L diesel engine equipped with an SCR ATS operated under low exhaust gas temperature. The engine experimental results show that, under 200°C exhaust temperature and 3.73x104 h-1 gross hourly space velocity (SV), the NOx conversion rate can be improved by 5% using 5-sec ON and 12-sec OFF (denoted as 5/12 s) urea pulse supply compared to the constant supply under time-averaged 1.0 urea equivalence ratio. It is experimentally observed that the urea pulse supply’s
Yoshida, FukaTakahashi, HideakiKotani, YuyaZu, QiuyueSok, RatnakKusaka, Jin
To gain high efficiencies and long lifetimes, polymer electrolyte membrane fuel cell systems require precise control of the relative humidity of the cathode supply air. This is usually achieved by the use of membrane humidifiers. These are passive components that transfer the product water of the cathode exhaust air to humidify the supply air. Due to the passive design, controllability is achieved via a bypass. It is possible to use map-based control strategies to avoid the use of humidity sensors. Such map-based control requires deep insights into the humidifier behavior in all possible thermodynamic operating states, including various water loads. This paper focuses on typical operating conditions of heavy-duty application at high load, specifically on the occurrence of liquid water in the cathode exhaust gas, which has not been sufficiently investigated in the literature yet. In order to simulate these conditions, we built a test rig with an optically accessible single-channel set
Mull, SophieWeiss, LukasWensing, Michael
Details of combustion — the chemical reactions that take place when, for example, a flame is lit — are fleeting and therefore, difficult to study. But scientists would like to better understand the complex processes that occur in those billionths of seconds, not only to make engines more efficient but also to shed light on how candle flames, cars, and airplanes produce gases and particles that are harmful to humans and the environment.
Ultrasound imaging and ultrasound-mediated gene and drug delivery are rapidly advancing diagnostic and therapeutic methods; however, their use is often limited by the need for microbubbles, which cannot transverse many biological barriers due to their large size. A team of researchers from Rice University have introduced 50-nm gas-filled protein nanostructures derived from genetically engineered gas vesicles(GVs) that are referred to as 50 nmGVs.
American drivers have long been accustomed to quickly filling up at a gas station with plenty of fuel available, and electric vehicle drivers want their pit stops to mimic this experience. Driver uncertainty about access to charging during long trips remains a barrier to broader EV adoption, even as the U.S. strives to combat climate change by converting more drivers.
Residual thermal energy, a by-product of automobiles, contributes notably to climate change and global warming. This energy is produced as exhaust gases in vehicles with internal combustion engines and as heat from batteries and fuel cells in eco-friendly vehicles. A thermo-electric generator (TEG) can transform this waste heat into useful electrical energy. The efficiency of the TEG is influenced by several factors, including the properties of the materials used, the geometrical design (form factor), and the conditions under which it operates. In this study, we examine how the choice of materials for the semiconductors, electrodes, ceramics, and joining components influences the overall performance of the TEG. We evaluate the TEG’s performance based on output power, and efficiency. The findings from these measurements allow us to determine which material and its properties significantly impact the TEG’s performance. For optimal TEG performance, seek materials with high Seebeck
Ponangi, Babu RaoMutagi, MeghaBali, Gaurav
To understand effect of thermal hazards of LIBs during TR event, it is important to study flame propagation behaviour of LIBs during storage and transport applications. The process of flame propagation involves complex phenomena of gas phase behavior of LIBs. Present paper attempts a numerical investigation to portray this complex phenomenon. This paper investigates 18650 lithium cell considering two different chemistries NMC and LFP. A 3D numerical CFD model has been constructed to predict the gas phase behavior, threshold internal pressure, and cell gas venting of an 18650-lithium cell under thermal runaway conditions. The gas phase processes are modelled using the 4-equation thermal abuse model, while the cell's venting mechanism is modelled using Darcy's equation. Present work is divided into two parts: 1) Venting gas Internal pressure prediction 2) modeling thermal runaway event. Both procedures are implemented on two different cell chemistries to understand and evaluate following
Gudi, AbhayBonala, Sastry
Increasing ignition energy by replacing standard spark igniters with pre-chambers is an established combustion accelerator. With rapid combustion on the one hand, mixture dilution can be extended while maintaining the combustion stability at adequate levels. On the other hand, accelerated combustion reduces the need for knock-induced spark retarding, thus facilitating emission reduction and increases in efficiency simultaneously. A newly developed pre-chamber ignition system is introduced in this work. The influence of the system on combustion is investigated in a single-cylinder research engine. The findings can support the development of future ignition technology for passenger-vehicle-sized engines. There are two basic configurations of pre-chamber igniters: the first is known as passive pre-chamber, the second as scavenged pre-chamber. The first configuration can be realized as a simple replacement for standard spark plugs. While additional costs are minimized, the air-fuel ratio
Fellner, FelixFitz, PatrickHärtl, MartinJaensch, Malte
Growing environmental concerns drive the increasing need for a more climate-friendly mobility and pose a challenge for the development of future powertrains. Hydrogen engines represent a suitable alternative for the heavy-duty segment. However, typical operation includes dynamic conditions and the requirement for high loads that produce the highest NOx emissions. These emissions must be reduced below the legal limits through selective catalytic reduction (SCR). The application of such a control system is time-intensive and requires extensive domain knowledge. We propose that almost human-like control strategies can be achieved for this virtual application with less time and expert knowledge by using Deep Reinforcement Learning. A proximal policy optimization (PPO) -based agent is trained to control the injection of Diesel exhaust fluid (DEF) and compared with the performance of a manually tuned controller. The performance is evaluated based on the restrictive emission limits of a
Itzen, DirkAngerbauer, MartinHagenbucher, TimoGrill, MichaelKulzer, Andre
If an external force with changing amplitude acts on an elastic medium such as a gas, a liquid or a solid, an undulating propagation of pressure and density fluctuation occurs in space and time, starting from the point where the force is applied. This is known as sound. The frequency of sound waves ranges from a few hertz (Hz) up to several gigahertz (see Figure 1). Infrasound, the sound humans cannot hear, lies at frequencies below 16 Hz. It is followed by the hearing range, which reaches up to 20 kHz. Ultrasonic waves, which cannot be heard, lie in the frequency range from 20 kHz to 1.6 GHz, which equals 16 billion cycles per second. A prominent application example in medical technology is the use of ultrasound for diagnostic imaging techniques. In industry and research, ultrasound is mainly used in measurement technology, where sound waves with low power are used. The intensity of the sound describes the power that hits a certain surface. If it exceeds 10 W/cm2, we speak of power
The study demonstrates the possibility and in particular the method to derive the efficiency of the entire fuel cell power system by measuring specific data of the recirculation path of the anode circuit of a fuel cell system. The results demonstrate the capabilities of the existing test rig and enable investigations on the suitability of auxiliary components. This study focuses on the hydrogen recirculation path equipped with multiple sensors and a needle valve to enable the required operating conditions of the fuel cell. Running a startup load profile without reaching the equilibrium state at all steps, the dynamic of the system and the requirements to the sensor parameters, such as sampling rate and precision, was seen. Additionally, it became obvious that the recirculation pump used is oversized, but a load point shift compensated this artifact. In detail, the stoichiometry and the efficiency of the entire system was evaluated. It was seen that the hydrogen concentration is
Allmendinger, FrankMartin, BenediktSchmidtmann, Marlen
Previous studies have shown that dosing AdBlue into the exhaust system of diesel engines to reduce nitrogen oxides can lead to an increase in the number of particles (PN). In addition to the influencing factors of exhaust gas temperature, exhaust gas mass flow and dosing quantity, the dosed medium itself (AdBlue) is not considered as a possible influence due to its regulation in ISO-standard 22241. However, as the standard specifies limit value ranges for the individual regulated properties and components for newly sold AdBlue, in reality there is still some margin in the composition. This paper investigates the particle number increase due to AdBlue dosing using several CPCs. The increase in PN is determined by measuring the number of particles after DPF and thus directly before dosing as well as tailpipe. Several AdBlue products from different sources and countries are measured and their composition is also analyzed with regard to the limit values regulated in the standard. This
Herold, TimNoone, PatrickBeidl, ChristianBoldt, ThomasHochholzner, MichaelKontin, Sinisa
AISI H13 hot work tool steel is commonly used for applications such as hot forging and hot extrusion in mechanical working operations that face thermal and mechanical stress fluctuations, leading to premature failures. Cryogenic treatment was applied for AISI H13 steel to improve the surface hardness and thereby fatigue resistance. This work involves failure analysis of H13 steel specimens subjected to cryogenic treatment and gas nitriding. The specimens were heated to 1020°C, oil quenched followed by double tempering at 550°C for 2 h, and subsequently, deep cryogenically treated at −185°C in the cryochamber. Gas nitriding was carried out for 24 h at 500°C for 200 μm case depth in NH3 surroundings. The specimens were subjected to rotating bending fatigue at constant amplitude loading at room temperature. Measurement of surface roughness, hardness, and microstructural analysis indicated improved fatigue life for cryogenically treated specimens as compared to gas nitride, which could be
Shinde, TarangMutalikdesai, SachinJomde, AmitShamkuwar, Sonal
Fossil fuel reserves are swiftly depleting when consumer demand for these fuels continues to rise. In order to meet the demand and diminish the pollution derived through conventional fuels, it is crucial to employ cleaner fuels made from substitutes such as waste biomass. Also, converting waste biomass to fuel can lower usage of landfills. There are many biomass resources that are suitable for fuel production, out of which groundnut is also a potential feedstock. Groundnut shell biomass was chosen for this study, as it is a waste leftover during shelling of groundnuts for various commercial applications. The procured groundnut shells were converted to oil using pyrolysis process and was distilled. Both the pyrolysis oil and the distilled oil were analyzed using Fourier transform infrared instrument wherein the presence of functional groups such as alcohols, amines, and carboxylic acids were identified. Further analysis of the distilled oil using gas chromatography and mass spectrometry
Chelladorai, PrabhuBalakrishnan, Navaneetha KrishnanKeerthiga, G.Singhvi, SambhavAtekov, Parahat
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