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Abstract Homogeneous Charge Compression Ignition (HCCI) is a promising advanced combustion concept with high efficiencies and low emissions. Chemical kinetic mechanisms and ignition delay correlations (IDCs) are often applied to simulate HCCI combustion. However, a large number of mechanisms and correlations are not developed specifically for HCCI conditions, i.e., lean mixtures and usually with significant residual gas fractions (RGF). To address this issue, a two-part study is conducted. First, experimental ignition delay time (IDT) data from literature under typical HCCI conditions is collected. Then, thirteen widely applied mechanisms for ethanol, natural gas, and primary reference fuel (PRF) blends of isooctane and n-heptane are validated by running constant-volume simulations. Their performance and accuracy are evaluated. Second, the mechanism with the highest accuracy for each fuel is used to generate IDCs for HCCI conditions.

Abstract This study focused on using adsorbents to suppress engine oil deterioration as a result of the influence of biodiesel. Engine oil performance is affected by the use of biodiesel that results in short period of oil drain interval. Neat base oil, 80% blended with biodiesel, was 20% thermo oxidatively aged. Magnesium aluminum hydroxycarbonate and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-buty-4-hydroxybenzyl)benzene were applied, and the formation of oligomers in the base oil-RME mixture was monitored. The adsorbents intercept the precursors of the aging procedure and, therefore, interfere with the aging process. The analysis with FTIR showed less to no formation of oligomers. About 90% reduction in the total acid number was observed, with about 90% reduction in viscosity increment. The adsorbents, therefore, have an enhanced influence on the oxidative stability of biodiesel and its blends.

Abstract This article presents surrogate mixtures that simulate the physical and chemical properties in the auto-ignition of hydrotreated vegetable oil (HVO). Experimental investigation was conducted in the Ignition Quality Tester (IQT) to validate the auto-ignition properties with respect to those of the target fuel. The surrogate development approach is assisted by artificial neural network (ANN) embedded in MATLAB optimization function. Aspen HYSYS is used to calculate the key physical and chemical properties of hundreds of mixtures of representative components, mainly alkanes—the dominant components of HVO, to train the learning algorithm. Binary and ternary mixtures are developed and validated in the IQT. The target properties include the derived cetane number (DCN), density, viscosity, surface tension, molecular weight, and volatility represented by the distillation curve. The developed surrogates match the target fuel in terms of ignition delay and DCN within 6% error range.

Abstract The development of a long-term sustainable hydrogen energy economy for commercial vehicle transportation will need to overcome key critical technical and logistics considerations in the near term. As compared to zero-emission powertrains, fossil-fuel-based powertrains provide mission flexibility and high uptime at a comparatively low total cost of ownership (TCO). While the incumbent carbon-intensive powertrains suffer from poor efficiency and are not sustainable to support global climate change initiatives in transportation decarbonization, techno-economic challenges continue to create complex barriers to the large-scale displacement of these with highly electrified powertrains architectures. This article specifically addresses opportunities that well-targeted subsidies would afford in achieving fuel cell electric powertrain financial parity with diesel powertrains in heavy-duty trucks (HDTs).

Abstract Sustainable practices are taking precedence across many industries, as evident from their shift towards the use of environmentally responsible materials, such as natural fiber-reinforced acrylated epoxidized soybean oil (NF-AESO). However, due to the lower reactivity of AESO, the curing reaction usually requires higher temperatures and longer curing time (e.g., 150°C for 6-12 h), thus making the entire process unsustainable. In this study, we demonstrate the potential power of photons towards manufacturing NF-AESO composites in a sustainable manner at room temperature (RT) within 10 min. Two photoinitiators, i.e., the 2,2-dimethoxy phenylacetophenone (DMPA) and 1-hydroxycyclohexyl phenyl ketone (HCPK), were evaluated and compared with the thermal initiator, i.e., tert-butyl perbenzoate (TBPB). Based on the mechanical performance of the AESOs, the photoinitiation system for NF-AESO was optimized.

Abstract Environmental protection and the depletion of nonrenewable energy sources necessitate the search for the replacement of, among others, diesel fuel (Df) in diesel engines with renewable fuel without major structural changes. For this reason, vegetable oils are of interest as a possible fuel for this type of engine. Unfortunately, the physicochemical properties of vegetable oils differ significantly from Df. In addition to the boiling and freezing points, these properties include viscosity, density, and surface tension as well as wetting properties. For this reason, an attempt was made to modify these properties by adding n-hexane (Hex) and ethanol (Et) to canola oil (Co). The viscosity, density, surface tension, and wetting properties of Hex and Et are significantly different from those for Co.

Abstract To assess the effect of the presence of carbon dioxide (CO2) in natural gases on the knock resistance of fuel, the knock behavior of a lean-burn, high-speed medium Brake Mean Effective Pressure (BMEP) Combined Heat and Power (CHP) engine fueled with CH4 + 8 mole% C3H8 mixtures. The engine experiments are supplemented with ignition measurements and simulations of ignition and cylinder processes for various fuel compositions. The engine results show that increasing the fraction of CO2 results in an increase in knock resistance. The analysis of simulations of cylinder processes shows that for binary mixtures (CH4/CO2) and ternary mixtures (CH4/C3H8/CO2) the increase in knock resistance with increasing CO2 fraction is caused by the reduction in peak pressure/temperature, which consequently increases the autoignition delay time of the mixture.

Abstract In the development of hydrocarbon (HC) traps for E85 fuel vehicle emission control, the addition of palladium (Pd) to BEA zeolite was studied for trapping and decreasing cold-start ethanol emissions. BEA zeolite after a laboratory aging at 750°C for 25 hours released nearly all of the trapped ethanol as unconverted ethanol at low temperature, and some ethene was released at a higher temperature by a dehydration reaction. The addition of Pd to BEA zeolite showed a decrease in the release of unconverted ethanol emissions even after the lab aging. The release of methane (CH4), acetaldehyde (CH3CHO), carbon monoxide (CO), and CO2 from Pd-BEA zeolite during desorption (temperature programmed desorption (TPD)) demonstrated that multiple ethanol reaction mechanisms were involved including dehydrogenation and decomposition reactions.

Abstract Combustion engines and liquid fuels are likely to continue playing a central role in freight transportation with renewable fuels reducing carbon emissions. Ethanol and methanol are future renewable fuels with a knock resistance that make them suitable for heavy-duty (HD) spark ignition (SI) engines. This simulation work focuses on the potential for improving the efficiency of an ethanol- and methanol-fueled HD SI engine using early intake valve closing Miller valve timing. With Miller valve timing, the expansion ratio and thermodynamic efficiency can be increased while maintaining the same effective compression ratio. However, Miller timing requires increased boost pressure to retain the same trapped air mass and also suffers from reduced in-cylinder turbulence.

Abstract High load (18 bar IMEP) dual fuel combustion of a premixed natural gas/air charge ignited by directly injected diesel fuel was studied in a large bore gas engine. A nozzle design with low flow rate was installed to inject a small diesel volume (10.4 mm3) equal an energetic amount of about two percent. The effect of compression end temperature on ignition and combustion was investigated using valve timings with early IVC (Miller) and maximum charging efficiency (MaxCC). Furthermore, the engine speed was reduced (1500 rpm to 1000 rpm) for the Miller valve timing to analyze the impact of the chemical time scale on the combustion process. During all experiments, the cylinder charge density was kept constant adjusting the intake pressure and the resulting air mass flow.

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Abstract The World Heritage Zones composed of tourists and permanent residents have the common need to protect the environment and to supply energy for electricity. The environmental, technological, and economic feasibility to transform waste into biofuels to provide energy with internal combustion engines has been demonstrated in several earlier pieces of research. A diffusion and adoption model to replace fossil fuels with biodiesel is proposed by utilizing System Dynamics simulations. This study uses the case of the Galapagos Islands as a reference and aims to depict the variables, values, and conditions under which alternative fuels can be considered a sustainable, affordable, and applicable solution. The purpose is to develop a dynamic system in which the current population and that expected to grow can adopt biodiesel as the main and only available fuel to reduce the environmental impact in vulnerable zones, like those declared as World Heritage.

Abstract Nowadays hydrogen, especially if derived from biomass or produced by renewable power, is rising as a key energy solution to shift the mobility of the future toward a low-emission scenario. It is well known that hydrogen can be used with both internal combustion engines (ICEs) and fuel cells (FCs); however, hydrogen-fuelled ICE represents a robust and cost-efficient option to be quickly implemented under the current production infrastructure. In this framework, this article focuses on the conversion of a state-of-the-art 3.0L diesel engine in a hydrogen-fuelled Spark Ignition (SI) one. To preliminarily evaluate the potential of the converted ICE, a proper simulation methodology was defined combining zero-, one-, and three-dimensional (0D/1D/3D) Computational Fluid Dynamics (CFD) approaches. First of all, a detailed kinetic scheme was selected for both hydrogen combustion and Nitrogen Oxides (NOx) emission predictions in a 3D-CFD environment.

Abstract Gasoline direct-injection (GDI) engines are increasing market penetration. They are attractive because they substantially decrease CO2 emissions and can increase fuel economy. However, due to their design, GDI engines are prone to increases in soot production. Blends of alcohols with gasoline have been observed to decrease soot production in GDI engines. However, results have been mixed, with publications suggesting either a decrease or an increase in soot production. Recent publications have indicated that increases in soot production are tied to fuel impingement onto the cylinder head during high-load engine periods. The work presented here utilizes an equation of state (EoS) model to understand the volatility characteristics of oxygenate-surrogate fuel blends, focusing on the volatility of aromatics. EoS calculations are rapid, and allow for the simulation of a broad range of temperatures and pressures.

Abstract Driving schedule of every vehicle involves transient operation in the form of changing engine speed and load conditions, which are relatively unchanged during steady-state conditions. As well, the results from transient conditions are more likely to reflect the reality. So, the current research article is focused on analyzing the biofuel-like lemon peel oil (LPO) behavior under real-world transient conditions with fuel injection parameter MAP developed from steady-state experiments. At first, engine parameters and response MAPs are developed by using a response surface methodology (RSM)-based multi-objective optimization technique. Then, the vehicle model has been developed by incorporating real-world transient operating conditions. Finally, the developed injection parameters and response MAPs are embedded in the vehicle model to analyze the biofuel behavior under transient operating conditions.

Abstract The complex hydropneumatic electromagnetic coupling structure of the dual-fuel injector leads to its complicated injection process. The unknown problem of fuel injection characteristics limits the injector design and optimization process of combustion efficiency. Therefore, the scientific study of dual-fuel injection mechanism and online identification method is the key to grasping the diesel-gas coupled injection mechanism, and an important theoretical basis for advanced closed-loop control. In this study, an identification method for the time characteristics of the dual-fuel injector injection process is based on the injector inlet pressure, which can be applied to the diesel-natural gas co-direct injection engine. First, the cause and transfer process of diesel injection pressure waves were analyzed based on the Riemann invariant theory.

Abstract Various feedstocks can be employed for biodiesel production, leading to considerable variation in composition and engine fuel characteristics. Using biodiesels originating from diverse feedstocks introduces notable variations in engine characteristics. Therefore, it is imperative to scrutinize the composition and properties of biodiesel before deployment in engines, a task facilitated by predictive models. Additionally, the international commercialization of biodiesel fuel is contingent upon stringent regulations. The traditional experimental measurement of biodiesel properties is laborious and expensive, necessitating skilled personnel. Predictive models offer an alternative approach by estimating biodiesel properties without depending on experimental measurements. This research is centered on building models that correlate mid-infrared spectra of biodiesel and critical fuel properties, encompassing kinematic viscosity, cetane number, and calorific value.

Abstract Particulate formation was studied under homogeneous-intent stoichiometric operating conditions when ethanol-blended (E10) or methanol-blended (M20) gasoline fuel was injected during intake stroke of a 4-stroke direct-injected engine. The engine was tested at wide open throttle under naturally aspirated conditions for a speed-load of 1500 rev/min and 9.8 bar indicated mean effective pressure. In-cylinder soot observations and exhaust soot measurements were completed for different fuel rail pressures, injection timings, coolant and piston temperatures of the optical engine. Fuel delivery settings were tested with both single and split injections during intake stroke. The target piston temperature of the optical engine was attained using pre-determined number of methane port fuel injection firing cycles. Overall, the in-cylinder soot observations correlated well with the engine-out soot measurements. A warmer cylinder head favored soot reduction for both fuels.

Abstract The airline industry faces a crisis in the future as consumer demand is increasing, but the environmental effects and depleting resources of kerosene mean that growth is unsustainable. Hydrogen is touted as the leading candidate to replace kerosene, but it needs significant technological and economical endeavors. In such a scenario, cryogenic liquid hydrogen (LH2) is predicted to be the most feasible method of using hydrogen. The major challenge of LH2 as an aircraft fuel is that it requires approximately four times the storage volume of kerosene—due to its lower density. Thus the design of cryogenic storage tanks to handle larger quantities of fuel is becoming increasingly important. But the increase in drag associated with larger storage tanks causes an increase in fuel consumption. Hence, this paper aims to evaluate the aerodynamic performance of different storage configurations and aid in the selection of an economic and efficient storage system.