Engine Exhaust Gas Research Articles

A comprehensive analysis of hydrogen fuel cell integration in fishing vessels

HHO gas is a fuel supplement produced through the electrolysis process of water in an HHO generator, where HHO gas falls under the category of alternative energy and is classified as a new energy source. The fundamental principle of internal combustion engines is generally to convert the chemical energy of liquid fuel into mechanical energy. The production of hydrogen through the electrolysis process is continuously evolving to facilitate the use of environmentally friendly fuels, with potential impacts on engine performance and exhaust gas emissions. This study examines the effect of adding HHO gas to electronic fuel injection (EFI) type-L gasoline engines on exhaust gas emissions and fuel consumption. It has been proven that the addition of HHO gas to the combustion process of gasoline engines, particularly EFI type-D, results in reduced emission levels (CO by 15.31% and HC by 16.27%). Moreover, the introduction of 0.1 Mol of HHO gas into EFI type-L engines through the air filter leads to a significant impact on exhaust gas emissions and a 2.8% increase in fuel consumption compared to not using HHO gas. This could be attributed to the distinct characteristics of EFI systems compared to conventional engines, as they are not accustomed to fuel supplements being injected into the engine.

Improving the operational characteristics of electrical power systems of marine vessels

THE PURPOSE. Consider the experience of use and conduct a study of the electrical power systems of sea vessels to determine the possibility of improving their operational characteristics. Obtain data on noise and vibration levels of electrical power systems elements.METHODS. The article analyzes the electrical power systems of the Azipod type steering columns of the Baltika icebreaker. The issue of regulating the rotation speed of propulsion electric motors using frequency control based on a DC link and parallel-connected inverter units on IGBT transistors is considered. Motor control on the frequency converter side can be based on direct torque control, scalar and vector control. There are control modes for reducing and increasing voltage.RESULTS. Typical dependences of structure-borne noise levels of main engines and generators are given. Measurements were taken at various frequencies of engine sound power levels, exhaust gases and vibration of generator sets. Experimental oscillograms of studies of the parallel operation of diesel generator sets were obtained, on which power exchange and common-mode oscillations were recorded.CONCLUSION. It is proposed to use multiphase AC electric motors to improve performance characteristics, including reducing noise and vibration. The existing experience in using frequency converters based on a rectifier section and inverter units in electric rowing installations with Azipod propellers makes it possible to implement such a change. To do this, it is necessary to parallelize the inverters that supply each of the three phases and provide the appropriate phase shifts.

Design and Fabrication of a LiBr Absorption Refrigeration System to Utilize the Waste Heat of Engine Exhaust Gas for Vehicle Cabin Cooling Application

Design and Fabrication of a LiBr Absorption Refrigeration System to Utilize the Waste Heat of Engine Exhaust Gas for Vehicle Cabin Cooling Application

The dynamic behaviour of ORC-based power units fed by exhaust gases of internal combustion engines in mobile applications

Exhaust gases Waste Heat Recovery (WHR) in Internal Combustion Engines (ICEs) performed through ORC-based Power Units (ORC-bPU) ensures a reduction of fuel consumption and consequently CO2 emissions. Nevertheless, high fluctuations of hot source push the ORC-bPU to work frequently in severe off-design conditions. Hence, a deep knowledge of the unit dynamic behaviour is fundamental to develop control and operating strategies allowing to achieve a successful recovery. Dynamic response assessment of ORC-bPUs has been treated in literature but making mainly reference to theoretical approaches or to variations of input variables without considering the matching to the engine and the necessary constraints which are present in a real mobile application. Moreover, Moving Boundary (MB) models are generally used as theoretical tools to support the dynamic analysis focusing the attention on Heat Recovery Vapor Generator (HRVG) which rules the plant dynamic response. In MB models, boundary conditions at the HRVG exit are mainly fixed by the expander and by the remaining circuit. To date, the attention was focused on the presence as expander of dynamic machines (turbine), deserving an evident lower attention to volumetric expanders nonetheless their higher suitability for low-medium scale ORC applications (few kWs). To fill these knowledge gaps, a novel approach is pursued in the present paper. The dynamic response of an ORC-bPU was experimentally observed for a step change of torque and revolution speed of an ICE directly connected to the recovery unit. The variation of engine operating conditions produced an unsteady variation of the temperature and flow rate of the exhaust gas feeding the unit. The dynamics of the engine and the connecting pipes is considered as well as all the typical constraints of a real situation. Results show HRVG and exhaust pipe ruling the dynamic behaviour of the unit, leading to long time constant and raising time of gas temperature of 150 s and 300 s respectively. These results show that the unit almost always works in transient conditions being engine torque and speed variations very fast. Nevertheless, thanks to the self-regulation capacity and the robustness of the scroll expander, the unit reacts in a satisfactory way. A further novelty of the present study concerns the integration of the widely used Moving Boundary (MB) approach with Permeability theory which considers the presence of a volumetric expander and all the ither downstream components, finding a match not available in literature between the HRVG and a volumetric expander and pump. The results of the new Permeability-Moving Boundary model (P-MB) was compared with those of a more comprehensive mathematical model. The comparisons show a comparable accuracy and a significantly lower computational time achieved with P-MB. Hence, P-MB could be implemented on board to set up control strategies enhancing the recovery tuned by a model-based approach.

Evaluation of Ecological Parameters of a Compression Ignition Engine Fueled by Diesel Oil with an Eco Fuel Shot Liquid Catalyst

This article discusses the potential applications of the Fuel Shot liquid catalyst in compression ignition (CI) engines for reducing toxic substances in exhaust gases. Incorporating catalysts into fuel can optimize the combustion process, consequently reducing the emission of toxic substances into the atmosphere. Toxic compounds, such as nitrogen oxides, particulate matter, and hydrocarbons, adversely affect flora and fauna. Various methods are known for reducing their concentration in engine exhaust gases, one of which is the Fuel Shot liquid catalyst. The authors conducted experiments on a Fiat 1.3 JTD engine with a Common Rail system. The results indicate that the application of the liquid catalyst reduces the content of nitrogen oxides and hydrocarbons in the exhaust gases and slightly decreases fuel consumption. Additionally, investigations were carried out on the engine’s injection apparatus, which was fueled with modified fuel. The findings demonstrate that the fuel additive does not affect the wear of precision parts of fuel injectors and high-pressure pumps.

Design and assessment of a novel mobile carbon capture system: Energy and exergy analyses

In this work, we designed a mobile carbon capture (MCC) system that can effectively capture CO2 from the exhaust gas of diesel engines for applications in commercial vehicles. We present the results of energy and exergy analyses conducted on this system, which includes an energy recovery unit, a cooling unit, CO2 adsorption and desorption units, and a CO2 liquefaction unit. Three processes were considered to capture CO2: temperature vacuum swing adsorption (TVSA), vacuum pressure swing adsorption (VPSA), and vacuum swing adsorption (VSA). Energy is produced using turbines and generators, which supply the necessary power to run the MCC system, thus overcoming the limitation of mobile devices, i.e., lack of energy source. The energy requirement for each process was found to be in the order of VPSA > TVSA > VSA. In terms of specific energy consumption (SEC) and exergy efficiency, VSA was the most suitable process. As an MCC system, the VSA process consumes a small amount of energy in the designed system, and CO2 can be captured, liquefied, and stored by utilizing the energy contained in the exhaust gas. Because the TVSA process is expected to operate with less additional energy input, it can be used as an MCC system to improve the efficiency of each process unit. Our study can serve as a basis for advancing carbon capture technologies that can be implemented in commercial vehicles to reduce the greenhouse effect and help control global warming.

Green and Efficient Recovery and Optimization of Waste Heat and LNG Cold Energy in LNG-Powered Ship Engines

This study focuses on the Wartsila 9L34DF engine and proposes an integrated system for low-temperature carbon capture using the coupling of cold and hot energy recovery with membrane separation in LNG-powered ships. By utilizing a series dual-pressure organic Rankine cycle (SDPORC) system to recover waste heat from the engine exhaust gases and generate electricity, the system provides power support for the low-temperature carbon capture compression process without consuming additional ship power. To validate the accuracy and reliability of the mathematical model, the simulation results are compared with the literature’s data. Once the model’s accuracy is ensured, the operational parameters of the integrated system are analyzed. Subsequently, working fluid optimization and genetic algorithm sensitive parameter optimization are conducted. Finally, under the optimal operating conditions, the thermodynamic performance and economic evaluation of the integrated system are assessed. The results demonstrate that the net power output of the integrated system is 100.95 kW, with an exergy efficiency of 45.19%. The unit carbon capture cost (UCC) is 14.24 $/ton, and for each unit of consumed LNG, 1.97 kg of liquid CO2 with a concentration of 99.5% can be captured. This integrated system significantly improves the energy utilization efficiency of ships and reduces CO2 emissions.

A novel bifunctional Pt/Ce/WZrOx catalyst for efficient selective oxidation of high-concentration NH3

A novel bifunctional catalyst with excellent NH3-SCO and NH3-SCR functions is effective to achieve excellent low-temperature activity and high N2 selectivity simultaneously, especially for removing high-concentration NH3 slipped from NH3-fuel engine exhaust gas. Herein, a small amount of noble metal Pt (0.1 wt%) was introduced in Ce/WZrOx to synthesize a novel bifunctional NH3-SCO catalyst. The experimental results showed that deposition order of Pt and Ce active species supported on WZrOx had a significant influence on NH3-SCO performance. Pt/Ce/WZrOx catalyst prepared through impregnation-precipitation method exhibited a much superior comprehensive NH3 removal performance compared to Pt/Al2O3 catalyst (Pt 0.1 wt%). It achieved an NH3 conversion of 96.4 % and a N2 selectivity of 94.2 % at 310 °C. A series of characterization tests were adopted to compare the physicochemical properties of Pt/Ce/WZrOx and Ce/WZrOx catalysts to reveal the possible functions of Pt and Ce active species in NH3-SCO reactions. The results of H2-TPR implied that there was a strong interaction between the Pt and Ce active species, which greatly enhanced the low-temperature redox property of Pt/Ce/WZrOx catalyst. Besides, electron transfer between Pt0/Ptn+ and Ce3+/Ce4+ cycles facilitated the generation of oxygen vacancies on the Pt/Ce/WZrOx catalyst surface, which played a key role in the reaction for removing high-concentration NH3. In-situ DRIFTS results suggested that NH3-SCO reactions over Pt/Ce/WZrOx catalyst might follow both imide (–NH) and hydrazine (-N2H4) mechanisms.

An Investigation of Engine Performance and Exhaust Gas Emissions under Load Variations using Biodiesel Fuel from Waste Cooking Oil and B30 Blend

An Investigation of Engine Performance and Exhaust Gas Emissions under Load Variations using Biodiesel Fuel from Waste Cooking Oil and B30 Blend

Real-time FPGA-based laser absorption spectroscopy using on-chip machine learning for 10 kHz intra-cycle emissions sensing towards adaptive reciprocating engines

Fast emissions sensing is needed to enable rapid optimization on-the-fly for increasingly adaptive engine architectures to improve performance over a wide range of loads and to offer fuel flexibility towards a low-carbon energy future. In this work, a real-time laser absorption spectroscopy technique is developed for 10 kHz on-line measurements of engine exhaust gas temperature and carbon monoxide. Latency due to data reduction is significantly shortened through a machine learning approach to spectral analysis and minimization of post-processing complexity for implementation on a high-bandwidth field-programmable gate array (FPGA). The data reduction method is tested on cycle-resolved laser-absorption thermochemistry measurements in reciprocating piston engine exhaust. The sensor employs a quantum cascade laser to spectrally-resolve two fundamental rovibrational absorption lines of carbon monoxide near 4.9 μm at a rate of 10 kHz. The recorded signals are passed to an FPGA to infer CO concentration and gas temperature through either a pre-trained ridge regression or artificial neural network model. Models are constructed to limit complexity with the aim of minimizing resource utilization and latency on the FPGA. Experimental data are used to evaluate the prediction accuracy of the models, with the neural network achieving RMS errors in CO mole fraction and gas temperature of 0.0390% and 15.0 K, respectively, compared to spectral fitting of the absorption lineshapes. The data reduction latencies are measured through hardware-in-the-loop demonstration, achieving a 10 kHz throughput and 25 μs latency. Computational time of the end-to-end data reduction process on the FPGA is measured at 300 ns and 600 ns for the ridge regression and neural network, respectively. The data reduction methods presented in this work expand the utility of laser absorption spectroscopy for low-latency sensors that match the timescales of combustion and increase the potential for real-time sensing and control to minimize engine exhaust emissions and maximize performance.

The use of digital twin technology in the testing laboratories of forest machines

One of the important environmental problems is the damage caused to the environment by the exhaust gases of internal combustion engines. They contain both non-toxic (nitrogen, carbon dioxide) and toxic (carbon monoxide, hydrocarbons, aldehydes, benzapyrene) chemicals that have a negative impact on both humans and nature. In addition to the daily operation of logging equipment, exhaust gases also occur during laboratory tests of internal combustion engines. In order to minimize the amount of exhaust gases during the study and testing of internal combustion engines of forest transport, the article proposes a variant of a digital twin, where by means of several tests of this sample, it will be possible to simulate other possible options, but with its electronic copy.

Copper loading effect on active species formation over Cu/SSZ-13 catalysts for selective catalytic oxidation of high-concentration NH3

Cu/SSZ-13 catalysts not only exhibit superior SCR performance but also possess excellent selective catalytic oxidation (SCO) ability to remove NH3 escaped from engine exhaust gas fueled by NH3. To elucidate the effect of Cu loading on Cu/SSZ-13 catalysts, a series of Cu/SSZ-13 catalysts were prepared through wet impregnation method to remove high-concentration NH3 (5000 ppm). The SCO activity test results showed that when Cu loading increased from 1% to 10%, there was an obvious improvement effect on NH3 conversion performance at low temperature. Cu10/SSZ-13 catalyst reached a high NH3 conversion of 96% at 250 °C, and N2 selectivity was higher than 86% in the whole temperature range. However, when further increasing Cu loading from 10% to 20%, there was no distinctive difference in NH3 conversion and N2 selectivity. The characterization results indicated that there were abundant active species, adsorbed oxygen species, and acid sites on the surface of Cu10/SSZ-13 catalyst. The [Cu(OH)]+ and isolated Cu2+ species in zeolite channels of Cu10/SSZ-13 catalyst rather than CuO species on the surface played a key role in NH3-SCO reactions. Since 20% Cu loading would result in a significant decrease in isolated Cu2+ species, it resulted in both [Cu(OH)]+ species in zeolite channels and superfluous Cu species on zeolite surface being main active species in NH3-SCO reactions. In-situ DRIFTS experiments suggested that NH3-SCO reactions over Cu/SSZ-13 catalysts followed the internal selective catalytic reduction (i-SCR) mechanism.

A Prediction of Graphene Nanoplatelets Addition Effects on Diesel Engine Emissions

There are numerous methods for reducing diesel exhaust emissions. Engine modifications, combustion optimization, and exhaust gas treatment are all popular methods. Another proven method uses fuel additives, such as zinc oxide, copper oxide, and magnesium oxide. Those additives are proven to reduce measured emissions such as carbon monoxide and nitrogen oxide successfully; however, there are still concerns about the toxicity of the emissions, which could harm human health. As a result, carbon nanoparticles have been introduced as a fuel additive due to their low risk to human health. Because of advancements in graphene research, a few researchers began investigating the implications of using graphene nanoplatelets as a fuel additive. The study’s findings appeared to be encouraging. However, no additional research has been identified to forecast the impact on engine emissions other than analyzing the effects of graphene additives on engine emissions. The goal of this study is to forecast the effects of graphene nanoplatelets on diesel engine emissions. The emission parameters of the trial were carbon monoxide, carbon dioxide and nitrogen oxide. The factors considered in the experiment are speed, load, and blend concentration. Response surface methodology and contour plots were generated using Minitab software. The results show that the prediction model’s accuracy is within 10% of the experimental data.

Solubility and stability enhancement of ethanol in diesel fuel by using tri-n-butyl phosphate as a new surfactant for CI engine

Nowadays, researchers are very interested in improving the stability and solubility of blending diesel fuel with a high percentage of ethanol. As a result, the goal of this paper was to find a way to use the surfactant of Tri-n-butyl phosphate (TBP) substance to blend ethanol with diesel fuel to a level of 40%. Diesel fuel is mixed with ethanol in volumetric proportions of 10%, 20%, 30%, and 40%, as well as a tiny amount of TBP from 1 to 4%. The prepared blends were the subject of an experiment evaluation by fueling a direct injection diesel engine. This engine is a water-cooled, commercial diesel engine, single cylinder, and four-stroke with 12 kW maximum power. The four blends were evaluated as clean fuel mixtures of 10% ethanol/90% diesel/1% TBP, 20% ethanol/80% diesel/2% TBP, 30% ethanol/70% diesel/3% TBP, and 40% ethanol/60% diesel/4% TBP. As the starting fuel, we used 100% diesel to compare the results. The engine’s output and emissions have been measured at various engine loads and constant speeds of 1500 rpm. According to the data gathered, even when the percentage of ethanol was increased to 40%, neither the base fuel nor the engine BTE changed significantly. The engine exhaust gas temperature was found to decrease slightly when the proportion of ethanol was increased. When bioethanol is increased to 40% of the base volume, it causes an increase in the combustion of unburned hydrocarbons and CO emissions. However, when the percentage of ethanol was increased from 100% diesel to the base fuel to 40%, CO2 emissions decreased, and O2 emissions slightly increased.

Performance evaluation of methane oxidation catalyst for marine gas-engine in actual exhaust and simulated gas

To reduce methane slip from marine gas engines installed in gas fuelled ships, it is necessary to understand the effects of exhaust composition and temperature on the activity of the methane oxidation catalysts in the marine gas engine exhaust. A comparative study was performed to evaluate catalyst performance in both actual engine exhaust and the simulated gas under the same flow conditions. The test using actual exhaust gas test showed that despite the lower exhaust temperatures during low load operation, the catalyst exhibited an extremely high performance, achieving approximately 100% CH4 conversion. In contrast, at high load, despite high exhaust temperatures, the CH4 conversion was decreased to 50-60%. In the simulated gas test showed that the catalyst’ activity was declined with increasing concentration of H2O and NO, whereas it was improved by CH4 and CO oxidation. The results showed that high CH4 concentrations under low load conditions enhanced catalyst activity owing to the exothermic reaction, which increased the catalyst temperature despite the low exhaust temperature and the presence of H2O vapour. Furthermore, during actual engine operation, the catalytic performance at a high load was improved by controlling the air excess ratio.

Numerical investigation of multi-designed mufflers in internal combustion engines for noise reduction

Some of the most harmful sources of noise pollution to humans are the exhaust gases of internal combustion engines and factory equipment such as compressors and turbines. An environment contaminated by these sounds can also cause brain cancer. These noise issues can be addressed by installing expansion chambers in the exhaust path. Although numerous studies have been conducted on mufflers, three-dimensional mufflers with non-coaxial inlet and outlet dimensions have not been emphasized in previous studies. To improve the acoustic attenuation performance of the reactive muffler, the effects of different parameters on transmission loss need to be investigated, which is performed in the present paper. The geometry of the muffler was considered one of the noise control parameters. The muffler was modeled using the Helmholtz equation and simulated in COMSOL for analysis. The results demonstrate that the noise level drops with an increase in length, width, and height. The optimal values for the length, width, and height of the muffler are calculated to be 700, 320, and 170 mm, respectively. In addition, the optimum size of the non-coaxial muffler is found 60 mm. Compared to existing mufflers, the proposed muffler reduces noise by 13% to 34%. These research findings will assist the automotive or other related industries to reduce the noise produced by vehicles and other industrial devices.

Abatement of photochemical smog precursors through complete hydrocarbon oxidation over commercial Pd catalysts under fuel-lean conditions with NO promoting effect

Currently, severe environmental issues have led to a great transition in the automotive industry from internal combustion engine vehicles to electric vehicles, but this transition will take time more than 10 years, which still requires the use of internal combustion engine vehicles. However, these vehicles emit a significant amount of hydrocarbons, in addition to nitrogen oxides (NOx), due to incomplete fuel combustion. They contribute to the formation of photochemical smog when they react with NOx in the presence of sunlight. To effectively remove these hydrocarbons from the exhaust gas of turbo-gasoline engines or diesel engines, we investigated the abatement of propane and iso-pentane, two typical hydrocarbons. In particular, we studied commercial Pd catalysts and revealed how the Pd loading and aging process simulating 4k and 100k mileage affected hydrocarbon abatement abilities, and their phases were identified using characterization technique, including CO chemisorption, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM). We also suggested the reaction pathway for the complete oxidation of propane over Pd catalyst based on the reaction orders of propane and oxygen: Propane adsorbs on O atoms of PdO, and the kinetically relevant C–H bond cleavage step occurs by the interaction with abundant neighboring O atoms of PdO. Finally, the propane and iso-pentane abatement ability of the Pd catalyst aged for 100k mileage were evaluated under realistic exhaust gas conditions, and the effect of each gas component in the realistic exhaust gas was identified; water inhibits the catalytic reaction of hydrocarbons by occupying the active sites, whereas NO catalyzes the hydrocarbon oxidation reaction by either changing the reaction pathway or active sites under fuel-lean conditions. These findings enable us to effectively reduce environmental pollution and facilitate a smoother transition from internal combustion engine vehicles to electric vehicles.

Crank angle-resolved mass flow characterization of engine exhaust pulsations using a Pitot tube and thin-wire thermocouples

Characterizing pulsating flow in high-temperature, high-pressure engine exhaust gas is crucial for the development and optimization of exhaust energy recovery systems. However, the experimental investigation of engine exhaust pulses is challenging due to the difficulties in conducting crank angle-resolved measurements under these unsteady flow conditions. This study contributes to characterizing mass flow pulses from an isolated cylinder exhaust of a heavy-duty diesel engine using a single-pipe measurement system, developed for pulsating flow measurement. A Pitot tube-based approach is adopted to measure exhaust mass flow pulsations, complemented by fast temperature measurements obtained using customized unsheathed thin-wire thermocouples. The on-engine experiment is performed by isolating the in-cylinder trapped mass and the valve opening speed to produce different exhaust pulse waveforms. The adopted approach’s sensitivity in resolving instantaneous mass flows is evaluated analytically and experimentally, considering attenuated temperature measurement effects. Based on exhaust flow measurements, mass flow pulses are analyzed with regard to blow-down and scavenge phases. Under the load sweep, the main waveform change occurs during the blow-down phase, with pulse magnitude increasing with the load. In contrast, as the engine speeds up with a comparable trapped mass, the exhaust mass distribution in the blow-down phase decreases from 75.5% at 700 rpm to 41.9% at 1900 rpm. Additionally, it is observed that cycle-to-cycle variations in mass flow pulses align with combustion stability during the blow-down phase and are predominantly influenced by gas-exchange processes during the scavenge phase.

Comparison of the Efficiency of Cleaning the Exhaust Gas of Internal Combustion Engines of Cars with Ultrasonic Emitters

. The conducted research is connected with ultrasonic cleaning of exhaust gases of internal combustion engines of passenger cars running on gasoline. A hypothesis is proposed for the use of ultrasonic radiation to clean exhaust gases from harmful impurities and solid particles. An experimental automobile muffler has been developed that simulates the ultrasonic cleaning process. The results of experimental studies are presented, proving the possibility and efficiency of using the process of ultrasonic cleaning from harmful impurities and solid particles. Experimental data on changes in toxic impurities and the dependence of the mass of solid particles (soot) on the settling distance are shown, which will be used in the calculation and design methodology when creating the design of an ultrasonic automobile muffler

Optimization of Diesel Engine Performance and Emissions Characteristics with Tomato Seed Blends and EGR Using Response Surface Methodology

The impact of load, Tomato Methyl Ester (TME), and Exhaust Gas Recirculation (EGR) enriched diesel on engine performance and exhaust gas emissions was examined in this study using the Response Surface Methodology (RSM) optimization technique. TME blend biodiesel (20, 40, and 60%) and EGR (10, 20 and 30%) were selected to maximize BTE and minimize BSFC, NOx, CO, smoke, and HC. The engine was operated using the RSM technique by load (0–100%). The results showed that the response variables were significantly influenced by load, TME and EGR concentration of engine. The results of the constructed quadratic models' analysis of variance (ANOVA) suggested that each model was an appropriate fit. Additionally, an optimal was found by optimizing the user-defined historical design of an experiment. The responses corresponding to optimal study factors were load 100%, TME Blend 20 and EGR 10% gives maximum BTE of 32.5%. The fuel consumption 0.2 kg/kW.h is reduced when load 50%, TME Blend 60 and EGR 10%. Smoke and NOx emissions were decreased by 15.09% and 49.04%, while CO and HC emissions were increased by 27.54% and 21.76%