Search Results

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 In recent years, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations. With this solution, in fact, it is possible to simultaneously reduce NOx raw emissions and fuel consumption due to decreased heat losses, higher thermodynamic efficiency, and enhanced knock resistance. However, the real applicability of this technique is strongly limited by the increase in cyclic variation and the occurrence of misfire, which are typical for the combustion of homogeneous lean air/fuel mixtures. The employment of a Pre-Chamber (PC), in which the combustion begins before proceeding in the main combustion chamber, has already shown the capability of significantly extending the lean-burn limit. In this work, the potential of an ultralean PC SI engine for a decisive improvement of the thermal efficiency is presented by means of numerical and experimental analyses.

Abstract In stationary natural gas engines, lean-burn combustion offers higher engine efficiencies with simultaneous compliance with emission regulations. A prominent problem that one encounters with lean operation is cyclic variations. Advanced ignition systems offer a potential solution as they suppress cyclic variations in addition to extending the lean ignition limit. In this article, the performance of three ignition systems-conventional spark ignition (SI), single-point laser ignition (LI), and prechamber equipped laser ignition (PCLI)-in a single-cylinder natural gas engine is presented. First, a thorough discussion regarding the efficacy of several metrics, in addition to coefficient of variation of indicated mean effective pressure (COV_IMEP), in representing combustion instability is presented. This is followed by a discussion about the performance of the three ignition systems at a single operational condition, that is, same excess air ratio (λ) and ignition timing (IT).

Abstract This work presents a numerical study of the performance and nitrogen oxides (NOx) emissions of a conventional ethanol engine converted to work as a flex-fuel nonconventional architecture: the Split-Cycle Engine (SCE). For this study, the conventional engine fueled with hydrous ethanol was modeled and validated with data from experimental tests. Then the model was converted to operate as an SCE with two compressors and two expanders and simulated with a progressive downsizing of the compressors of the SCE. When the swept volume of the compressors was reduced to 87% of that of the expanders, the thermal conversion efficiency increased by 3.3%. Because of this, the downsized SCE was submitted to simulation runs using two different fuels: hydrous ethanol (H100) and an indolene-ethanol blend (H85). The results of the simulations were compared to the experimental results of the conventional engine.

Abstract With the reduction in PM emission standards for light duty vehicles to 3 mg/mi for current Federal and California standards and subsequently to 1 mg/mi in 2025 for California, the required PM measurements are approaching the detection limits of the gravimetric method. A “filter survey” was conducted with 11 laboratories, representing industry, agencies, research institutes, and academic institutions to analyze the accuracy of the current gravimetric filter measurement method under controlled conditions. The reference filter variability, measured within a given day over periods as short as an hour, ranged from 0.61 μg to 2 μg to 5.0 μg for the 5th, 50th, 95th percentiles (n > 40,000 weights, 317 reference objects), with a laboratory average of 2.5 μg.

Abstract In order to improve performance and minimize pollutant emissions in gasoline turbocharged direct-injection (GTDi) engines, different injection strategies and technologies are being investigated. The inclusion of exhaust gas recirculation (EGR) and the variation of the start of injection (SOI) are some of these strategies that can influence the air-to-fuel (AF) mixture formation and consequently in the combustion process and pollutant emissions. This paper presents a complete study of the engine performance, pollutant emissions and aftertreatment efficiency that produces the SOI variation with a fixed EGR rate in a 4-cylinder, turbocharged, gasoline direct-injection engine with 2.0 L displacement. The equipment used in this study are TSI-EEPS for particle measurement and HORIBA MEXA 1230-PM for soot measurement being HORIBA MEXA 7100-DEGR with a heated line selector the system employed for regulated gaseous emission measurement and aftertreatment evaluation.

Abstract The rapid utilization of fossil fuels has triggered the finding of alternative renewable fuel that replaces or reduces the consumption by alternative fuels for fueling compression ignition (CI) engines. One such renewable fuel is ethanol which can be manufactured from biomass. The present study details the utilization of an optimum amount of ethanol in CI engine by modifying the operating parameters. It was already published in the previous paper that 45% ethanol can be utilized along with diesel using 10% butanol as cosolvent. This fuel is also meeting the minimum requirement with respect to properties as per ASTM standards. This experimental study was performed to investigate the influence of modifying the engine operating parameters on the performance, combustion, and emission parameters fueled with the blend containing 45% ethanol under various load conditions.

Abstract TOC

Abstract To overcome the limitations such as lower combustion efficiency (CE) and higher cyclic variability in methanol/diesel (M/D) reactivity controlled compression ignition (RCCI) combustion, a fuel having higher reactivity than diesel (i.e., polyoxymethylene dimethyl ethers, PODE) was used in our previous study. Methanol/PODE RCCI combustion resulted in improved CE and reduction in soot and unburned emissions compared to M/D RCCI combustion. However, it was noticed that the use of neat PODE as high-reactivity fuel had damaged the fuel line materials frequently due to its higher oxygen content and lower viscosity. In addition, Methanol/PODE RCCI has also resulted in higher NO emissions compared to M/D RCCI combustion.

Abstract The aim of this article is to analyze the energy recovery of synthesis gases in an internal combustion engine, in terms of both their general behavior and recommendations for their future composition in production. This article presents an experimental analysis of power and economical parameters of internal combustion engine as a source of propulsion for a cogeneration unit. The power parameters were measured using 13 various low-energy synthesis gases as fuels. Most of them are methane-free synthesis gases. The main components of these synthesis gases were hydrogen, carbon monoxide, methane, carbon dioxide, and nitrogen. The composition of the synthesis gases responded to various waste gasification technologies. The mass lower heating value of the selected synthesis gases ranged from 4 to 8 MJ/kg.

Abstract It has been shown that appropriate regulation of parameters of the gas supply system control algorithm allows to reduce the emission of selected components of the exhaust gas (carbon monoxide [CO], hydrocarbon [HC], and oxides of nitrogen [NOx]). The test engine met the Euro 6 standard on petrol and was equipped with an additional alternative multipoint fuelling system for multipoint injection (MPI) of the gaseous phase liquefied petroleum gas (LPG). The tests are comparative in nature. The first test to compare LPG petrol fuelling was carried out in the New European Driving Cycle (NEDC) where small differences in emissions were shown. The second part of the test compared emissions in the Worldwide harmonized Light vehicles Test Cycle (WLTC), wherein the initial phase there was a significant difference in emissions to the detriment of the gas supply. An innovative approach was therefore proposed to correct settings in the gas system control algorithm.

Abstract In current production natural gas/gasoline bi-fuel vehicles, fuels are supplied via port fuel injection (PFI). Injecting a gaseous fuel in the intake port significantly reduces the volumetric efficiency and consequently torque as compared to gasoline. In addition to eliminating the volumetric efficiency challenge, direct injection (DI) of natural gas (NG) can enhance the in-cylinder flow, mixing, and combustion process resulting in improved efficiency and performance. A computational fluid dynamics (CFD) approach to model high-pressure gaseous injection was developed and validated against X-ray data from Argonne’s Advanced Photon Source. NG side and central DI of various designs and injection strategies were assessed experimentally along with CFD correlation. Significant effects on combustion metrics were quantified and explained via improved understanding of the in-cylinder flow effects due to NG injection.

Abstract Directly injecting fuel in two-stroke spark-ignition (2S-SI) engines will significantly reduce fuel short-circuiting losses. The liquid phase liquefied petroleum gas (LPG) DI (LLDI) mode has not been studied on 2S-SI engines even though this fuel is widely used for transportation. In this experimental work a 2S-SI gasoline-powered engine used on three-wheelers was modified to operate in LLDI mode with an electronic engine controller. The influences of injection pressure (IP), end of injection (EOI) timing, location of the spark plug, and type of injector on performance, combustion, and emissions were studied at different operating conditions. EOI close to bottom dead center with the spark plug located near the exhaust port was the most suitable for the LLDI mode which significantly enhanced the fuel trapping efficiency and improved the thermal efficiency.

Abstract Internal combustion (IC) engines are widely used in automotive, marine, agricultural and industrial machineries because of their superior performance, high efficiency, power density, durability and versatility in size and power outputs. In response to the demand for improved engine efficiency and lower CO2 emissions, advanced combustion process control techniques and more renewable fuels should be adopted for IC engines. Lean-burn combustion is one of the technologies with the potential to improve thermal efficiencies due to reduced heat loss and higher ratio of the specific heats. In order to operate the IC engines with very lean air/fuel mixtures, multiple turbulent jet pre-chamber ignition has been researched and developed to extend the lean-burn limit. Turbulent Jet Ignition (TJI) offers very fast burn rates compared to spark plug ignition by producing multiple ignition sites that consume the main charge rapidly.

Abstract The search for new solutions for engine ignition systems and combustion of lean air-gas mixtures has led to the application of a two-stage combustion system, previously also known as turbulent jet ignition (TJI). In this article, the authors proposed using a pre-chamber filled with a rich ignition mixture, which is turned into an outgoing burning jet that facilitates the combustion of lean mixtures in the main combustion chamber. Various two-stage combustion systems were tested in a high-speed natural gas-powered combustion engine as a part of the Horizon 2020-GasOn (Gas-Only Internal Combustion Engines) research program. The results of testing the effectiveness of using various pre-chambers are discussed in this article. These tests were carried out in a selected engine’s operating range using three pre-chambers with different geometry. The first phase of the research concerned the selection of a gas supply system (injection on the intake valve or Heinzmann mixer).

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 The addition of a spark plug in place of the original fuel injector and fumigating natural gas (NG) inside the intake manifold is an economical way to convert heavy-duty diesel engines to NG spark-ignition (SI) operation. The literature shows that, when compared to a conventional SI engine combustion chamber, the different in-cylinder flow motion, turbulence intensity distribution, and interaction of propagating flame with chamber boundaries in these converted engines produce distinctive combustion stages. As the current understanding of how these combustion stages affect the engine performance is limited, this study used a triple-Wiebe combustion model to determine the effect of spark timing (ST) on the phasing and mass fraction of each combustion stage, at lean operation (ϕ = 0.73) and low engine speed (N = 900 rpm).

Abstract With the increased use of low ignition quality fuels in advanced compression ignition engines, the extended ignition delay and two-stage ignition behavior shown on the measured in-cylinder pressure profile raise a question about at what point of the pressure trace should be identified as the start of combustion (SOC). Previous studies used numerous methods, but a systematic evaluation is lacking, particularly for low ignition quality fuels used in a small-bore engine. The present study bridges this gap by performing high-speed imaging of OH* chemiluminescence in a small-bore optical compression ignition engine, against which various methods of ignition delay calculation are assessed for a correct representation of the start of high-temperature reaction—i.e., the actual SOC.

Abstract In the last few years, reactivity-controlled compression ignition (RCCI) mode combustion has gained researchers’ attention due to its superior performance, combustion, and emission characteristics compared to other low-temperature combustion (LTC) strategies. In this study, RCCI mode combustion investigations were carried out to explore the effects of exhaust gas recirculation (EGR) and intake charge temperature (ICT) on combustion, performance, and emission characteristics of a mineral diesel/methanol-fueled engine. In this study, constant engine speed (1500 rpm) and load (3 bar brake mean effective pressure [BMEP]) were used to perform engine experiments. The premixed ratio (rp) of methanol was varied from rp = 0 to rp = 0.75, where rp = 0 represents the baseline compression ignition (CI) mode combustion. At all rp, EGR rate and ICT were varied from 0 to 30% and 40° to 80°C, respectively.

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.