Engine Efficiency Research Articles

Development of a Golden Gate Assembly-Based Genetic Toolbox for Lactiplantibacillus plantarum and Its Application for Engineering Monoterpenoid Biosynthesis.

Lactiplantibacillus plantarum is a food-grade lactic acid bacterium widely used in the food and beverage industry. Recently, this probiotic organism has been applied as a biofactory for the production of pharmaceutical and food-related compounds, but existing promoters and expression vectors for the genetic engineering of L. plantarum rely on inefficient cloning strategies and are usually not well-characterized. We therefore developed a modular and standardized Golden Gate Assembly-based toolbox for the de novo assembly of shuttle vectors from Escherichia coli to L. plantarum. A collection of the most relevant genetic parts, e.g., different origins of replication and promoters, was incorporated in our toolbox and thoroughly characterized by flow cytometry and the fluorescence assay. Standardized fusion sites allow combining the genetic part freely into a plasmid in one step. This approach allows for the high-throughput assembly of numerous constructs in a standardized genetic context, thus improving the efficiency and predictability of metabolic engineering in L. plantarum. Using our toolbox, we were able to produce the aroma compounds linalool and geraniol in L. plantarum by extending its native mevalonate pathway with plant-derived monoterpenoid synthases.

RESEARCH OF THE COMBUSTION PARAMETERS OF GASOLINE WITH ADDITIONAL HYDROGEN IN A SPARK-IGNITION ENGINE IN EXTERNAL SPEED CHARACTERISTIC MODES

The directions of development and improvement of road transport around the world are inextricably linked to the desire to reduce the use of cars “on traditional fuels” due to limited oil and environmental safety of mankind. Since the modes of external speed characteristic are the most typical for the operation of cars in cities, the study of environmental performance of engines in these modes is an urgent task. Therefore, finding ways to reduce carbon dioxide emissions from automobile engines at high-speed modes is an urgent task. The rapid growth in the number of cars with internal combustion engines and the inevitable decline in world oil reserves necessitate the development and implementation of energy-saving technologies and the use of alternative fuels. Research aimed at finding ways to improve the fuel efficiency and environmental performance of automotive engines is relevant. One of the promising areas is the influence on the combustion process in gasoline engines by using additives of alternative fuels, which include hydrogen. The presented study of the parameters of combustion of gasoline with hydrogen additive in a spark ignition engine at external speed characteristics is a comprehensive analysis of the combustion process of a gasoline-hydrogen mixture and determination of its effect on the concentration of carbon dioxide in exhaust gases by developing a mathematical model that takes into account the composition of the mixture components and features of the combustion process, allows for sufficiently accurate calculation of the operating process of an engine with hydrogen additive at ψ ≤ 10%, its identification by the results of experiments. In the course of the study, dependencies were developed to determine the combustion parameters of the Wiebe model, taking into account the addition of hydrogen to gasoline in the modes of external speed characteristics, and the effect of hydrogen addition on the concentration of CO2 in exhaust gases was analyzed. It is shown that with an increase in the hydrogen additive to 10% by mass fraction to gasoline, there is a decrease in CO2 emissions to almost 30% in the external speed characteristic modes, which corresponds to modern environmental standards for gasoline internal combustion engines.

Impact of cylinder deactivation on fuel efficiency in off-road heavy-duty diesel engines during high engine speed operation

Off-road heavy-duty diesel engines are equipped with complex aftertreatment systems to meet the stringent EPA Tier 4 emission standards. Traditionally, the thermal management of the aftertreatment system, aimed at efficiently reducing tailpipe emissions, involves controlling engine exhaust flow and temperature. However, this approach often leads to inefficient engine operation, especially in the low to mid-load regions, resulting in higher fuel consumption. Prior studies have highlighted the potential of cylinder deactivation (CDA) in reducing fuel consumption and increasing the exhaust temperature for thermal management in on-road applications. As the significance of controlling greenhouse gas (GHG) emissions from off-road machinery comes into focus, this study aims to experimentally demonstrate the fuel efficiency benefits and efficient aftertreatment thermal management achieved through CDA during high-speed operation on a Tier 4 level off-road heavy-duty diesel engine. In a typical off-road duty cycle, such as Non-Road Transient Cycle (NRTC), about 82.5% of cycle’s energy is produced in the engine speed range of 1750–2200 rpm, prompting investigation into the impact of CDA during high-speed operations. CDA results in airflow reductions and increased exhaust gas temperatures due to lower air–fuel ratio (AFR). The reduced airflow operation minimizes pumping work, allowing for higher open cycle efficiency, and thereby translating into lower fuel consumption. The study reveals a new finding: fuel benefits from CDA extend over a larger load range (up to 8.3 bar BMEP) during high-speed operation in off-road heavy-duty engines compared to findings in on-road heavy-duty engines. This phenomenon can be attributed to sufficient oxygen inducted during CDA operation, resulting from similar turbocharger speeds compared to all-cylinder firing operation, especially at high-loads, thereby maintaining particulate matter (PM) concentration within prescribed constraints. Steady-state test results demonstrate a reduction in fuel consumption from 33.7% at 0.4 bar to 1.4% at 8.3 bar BMEP, at 2100 rpm engine speed.

The performance of a spark ignition gasoline engine with hydrogen addition under low-load conditions

With continuously increasing populations and industrialization, more and more green consumers and stringent emission regulations promote low-carbon or zero-carbon alternative fuels in transportation sector. Hydrogen is considered carbon-free when produced using environmentally friendly methods, and could achieve zero carbon emission in the internal combustion engines. This study comprehensively explores the influences of the hydrogen addition on the performance of the gasoline spark ignition (SI) engine operated at low-load conditions. The experimental results showed that the abnormal combustion cycles of the test gasoline engine are greatly reduced with hydrogen enrichment. In addition, the coefficient of variation (COV) of the indicated mean effective pressure (IMEP) of the gasoline engine is 2.66 % under the 1500 rpm and 0.2 Mpa (brake mean effective pressure: BMEP) condition, while the COV of IMEP of the engine fuelled with gasoline and hydrogen is 2.34 % at the same condition. Furthermore, the knocking intensity of the gasoline engine is strengthened by adding hydrogen because the averaged maximum pressure rise rate (MPRR) of the gasoline SI engine is slightly increased. Besides, the indicated thermal efficiency (ITE) of the gasoline engine is increased 0.9 % and its maximum increase rate of the ITE is 4.27 % with hydrogen addition at the 1300 rpm and 0.2 MPa condition. Last, unburned HC, CO, and CO2 of the gasoline engine are reduced while NOx emissions increase with adding hydrogen due to high combustion temperature.

MODELING OF MIXTURE FORMATION IN A TWO-STROKE DIESEL ENGINE

The Ukrainian engine industry played a significant role in the creation, production, and improvement of the efficiency of two-stroke diesel engines with opposed mooved pistons and providing them with the highest indicators of liter and overall power. The results of research carried out at the department of engines and hybrid power plants of NTU "KhPI" reveal existing reserves for further improvement, ensuring world-class indicators and forming promising characteristics of two-stroke diesel engines of the 6DN12/2x12 series. Further developments to ensure a new level of power cannot be implemented exclusively by updating auxiliary units and systems. To create a promising power plant, the problem must be considered in a complex with an understanding of the physical and chemical processes in the engine cylinder. The two-stroke cycle and design features limit the possibilities of conducting experimental studies of engines of this type, and make it necessary to determine reserves for increasing their efficiency. In this case, the dissemination of ideas about the course of mixture formation processes in a two-stroke engine with lateral fuel injection becomes an urgent scientific and practical task. Solving this problem makes it possible to determine the reserves of increasing combustion efficiency in engines with reciprocating movement of pistons. Based on the results of the research, a mathematical model is proposed that allows us to determine the most rational ways of organizing mixture formation, provided the conditions of uniform distribution of fuel in the volume of the combustion chamber are ensured. The obtained results of the calculated studies are the basis for the development of structural elements, further experimental studies and the implementation of measures to ensure the further improvement of the mixing efficiency of two-stroke diesel engines of the 6DN12/2x12 series and their modifications.

CRITERIA FOR ASSESSING THE EFFECTIVENESS OF TRANSPORT POWER PLANTS DECARBONISATION IN ACCORDANCE WITH IMPLEMENTATION OF THE SUSTAINABLE DEVELOPMENT CONCEPT

The directions of restoration and further development of the energy sector in Ukraine are considered in accordance with power plants with internal combustion engines, taking into account the widespread implementation of the Sustainable Development concept, which allows solving existing modern social, economic and environmental problems. For Ukraine, taking into account the economic opportunities and selected priorities for the chosen path of development, it is necessary at this time to choose gradual and specific directions to implement the Sustainable Development concept. The most priority areas of practical implementation of the concept are determined and it is indicated that the effectiveness of this implementation is associated with the development of the industry on the basis of the fourth and fifth industrial revolutions (Industry 4.0 and Industry 5.0). One of the main tasks in solving the problems of the concept is to ensure the environmental component. Notwithstanding the noted progress in improving the environmental efficiency of internal combustion engines, further attention needs to be paid to the task of spreading the introduction of “green energy”, i.e. decarbonisation – reducing greenhouse gas emissions into the environment (CO2). The issue of decarbonisation in the future should be given the greatest attention both in the development and in the manufacture and operation of engines. It is shown that the assessment of the impact of CO2 emitted with the exhaust gases of internal combustion engines into the environment is carried out taking into account the model of operation of engines and the justification of the introduced adjustments. A new criterion is proposed, which is called: “ICE criterion of environmental thermal pollution”, which is proposed for use in studies to assess the effectiveness of the implementation of decarbonisation strategies in all modes of transport at implementation of the Sustainable Development concept in global transport power plants. A method for determining the efficiency of physical and chemical processes of mixture formation and combustion in internal combustion engine cylinders is proposed when using hybrid fuel with “green hydrogen” as its component, which allows determining the dependence of hydrogen influence on the level of engines effective performance and formation of harmful emissions in exhaust gases.

ADVANTAGES AND FEATURES OF USING DIGITAL TWIN TECHNOLOGY FOR STATIONARY GAS ENGINES

At the moment, there is no mass alternative to power plants based on an internal combustion engine. Such power plants are fully mastered in production, they are mobile, not bulky, and do not depend on weather conditions (wind, current, etc.), as required by wind and hydroelectric power plants. The variety and availability of fuels is also a very big advantage in favour of internal combustion engines. On the other hand, engines are a source of heat, noise and chemical pollution, and by running on fossil fuels, they contribute to negative climate change on the planet, so the issue of improving the fuel, economic and environmental efficiency of vehicle engines is relevant. With the rapid development of information technology, it is now possible to create a perfect control system for stationary engines using digital twin technology, which in the future could take over the entire task of controlling the unit with minimal human intervention, eliminating the effect of the human factor and thereby increasing the life and efficiency of the unit. The goal is to use the forecasting system to assess the actual technical condition of the engine and, based on this data, set the optimal maintenance intervals, as well as prevent accidents that entail expensive repairs or even complete replacement of the unit. Such a system would be relevant for large, expensive stationary machines involved in any technological processes where the unit's downtime entails financial losses associated with the cessation of a particular production process. Representatives of this type of power plant are gas engines - drives for booster or downhole gas compressors, gas generators operating on landfill gas or biogas.

Design, optimisation and evaluation of the S-CO2 Brayton cycle for marine low-speed engine flue gas

Five configurations of the S-CO2 Brayton cycle (SCBC) were constructed for flue gas waste heat recovery (WHR) of the marine low-speed engine HHM-6EX340EF on the EBSILON platform using the bench test data to save energy, reduce emissions and the efficient operation of ocean-going vessels. Experimental data from Sandia National Laboratories (SNL) was utilised to validate the accuracy of the model and the effect of Brayton cycle parameters on flue gas WHR for different configurations was analysed. The parameters of the SCRBC (S-CO2 recompression Brayton cycle) were optimised by combining the Neural Network Fitting (NNF) model, Multi-objective optimisation algorithms, and multi-criteria decision-making methods. Finally, the thermodynamic analysis of the low-speed engine was comprehensively evaluated by comparing five configurations of SCSBC (S-CO2 simple Brayton cycle), SCCBC (S-CO2 recuperative Brayton cycle), SCHBC (S-CO2 reheating Brayton cycle), SCIBC (S-CO2 intercooling Brayton cycle), and SCRBC. The optimised SCIBC configuration had the highest net recuperated work of 195.76 kW and the highest Brayton cycle efficiency of 20.13 %. The engine efficiency was improved by 0.82 %, 1.45 %, 1.78 %, 1.86 % and 1.68 %, the BSFC was decreased by 3.20 g/kW·h, 5.56 g/kW·h, 6.82 g/kW·h, 7.04 g/kW·h, and 6.43 g/kW·h, and the output power increased by 86.90 kW, 153.33 kW, 195.76 kW, 189.36 kW, and 178.14 kW, respectively. The maximum exergy loss of the cooler was 162.67 kW with an exergy loss efficiency of 14.54 % in the SCSBC configuration. Optimising the flue gas heat exchanger and cooler will further enhance the efficiency and reduce emissions. Research on the parameter and configuration optimisation of the SCBC for marine low-speed diesel engines can be extended to other low-speed engines.

A calculation algorithm for the heater of a Stirling engine

Abstract The paper presents a calculation algorithm for the heater of a Stirling engine. In the current context of the energy crisis, Stirling engines can be used to produce mechanical work from renewable energy sources. The heat exchangers are one of the key elements regarding the efficiency of a Stirling engine. So, a calculation algorithm for the heater of a Stirling engine can be used for the dimensioning of this component, according to the requirements for the functioning of the system. To validate this algorithm, a dedicated program for the calculation of the heat exchangers based on the finite element analyse was used.

Research on the performance optimization of the cam linkage mechanism for marine diesel engines

Abstract In this paper, the impact of friction and wear in the flat bottom mechanism of a diesel engine on the reliability and durability of the valve train is investigated. A method for establishing a dynamic contact model is proposed, including the establishment of the cam profile equation, force analysis at the contact point, calculation of the curvature radius, and derivation of contact stress. Through the derivation of wear depth and structural optimization analysis, the proposed method can be used to optimize the cam profile and improve the service life and work efficiency of the valve train. The results show that the optimized cam follower’s life is increased by 31.8%, and the contact stress is decreased by 16.5%. This study is of great significance for improving the power and efficiency of diesel engines.

Brayton Cycle Analysis of the Effect of Wake Ingestion on Aircraft Range

The effect of wake ingestion on the propulsive efficiency of turbojet and turbofan engines has been examined to determine the effect of wake ingestion on jet aircraft range. In a new approach, the Brayton turbine cycle was analyzed to show how wake ingestion affects the thrust and specific fuel consumption of jet engines. It is argued that it is not necessary to add an expression for propulsive efficiency to the Breguet range equation, because the thrust-specific fuel consumption is an explicit function of the inlet Mach number. It is concluded that wake ingestion does not increase the aircraft’s maximum range because it reduces the engine’s maximum thrust.

The study on the engine pressure variation of utilizing n-butanol-gasoline blends at fueling spark ignition engines

Abstract Alternative fuel solutions are highly regarded as potential solutions to more emissions regulation as well as more efficient energetic consumption requirements. The more efficient combustion engines become, the lesser resources they require to propel vehicles thus resulting in lower carbon footprint and lower pollutants such as CO, HC and NOx. Alcohols are promising alternative fuels that can be used to fuel vehicles, on their own or in blends with conventional fuels such as gasoline and diesel. A lot of studies have been done on alcohols such as ethanol, butanol and methanol. Each of the mentioned solutions have their advantages and disadvantages. Butanol looks a promising solution due to its high miscibility properties making it possible to blend in higher percentages with other fuels such as gasoline for example. Compared to ethanol, butanol is also less corrosive, making it ideal for older vehicles as well without any modifications to the fuel systems. Many studies have shown that the high oxygen content of butanol can help improve the combustion process in spark ignition engines, may improve thermal efficiency resulting in lower emissions and better overall engine stability. An improved engine stability can be measured by a lower variability between engine cycles during engine functioning. The objective of this paper is to determine the impact of fueling a spark ignition engine with a blend of 15% vol. n-butanol – 85% vol. gasoline on pressure variability and combustion. No engine adjustments/optimizations are done at fueling with the blended fuel vs pure gasoline. The baseline was set at an engine speed of 2500 min-1 and load of 55% while fueling with pure gasoline. After setting the baseline, the same measurements are done at fueling with the blended fuel.

Jatropha Oil Biodiesel: Production Process, Fuel Characterization and Engine Efficiency Evaluation

Jatropha Oil Biodiesel: Production Process, Fuel Characterization and Engine Efficiency Evaluation

Trapped-atom Otto engine with light-induced dipole–dipole interactions

Abstract Finite-time quantum heat engines operating with working substances of quantum nature are of practical relevance as they can generate finite-power. However, they encounter energy losses due to quantum friction, which is particularly pronounced in many-body systems with non-trivial coherences in their density operator. Strategies such as shortcuts to adiabaticity and fast routes to thermalization have been developed although the associated cost requirements remain uncertain. In this study, we theoretically investigate the finite-time operation of a trapped-atom Otto engine with light-induced dipole–dipole interactions and projection measurements in one of the isochoric processes. The investigation reveals that when atoms are sufficiently close to each other and their dipoles are oriented perpendicularly, light-induced dipole–dipole interactions generate strong coherent interactions. This has enhanced engine efficiency to near unity and accelerate the thermalization process by sixtyfold. The interactions also boost engine performance during finite-unitary strokes despite the significant quantum friction induced by the time-dependent driving field. Furthermore, the projection measurement protocol effectively erases quantum coherences developed during both the finite-unitary expansion and finite thermalization stages and allows finite-time engine operation with an output power. This setup presents a compelling avenue for further investigation of finite-time many-body quantum heat engines and provides an opportunity to explore the full potential of photon-mediated dipole–dipole interactions.

Comparison of machine learning algorithms on a low heat rejection diesel engine running on ternary blends

Depletion of fossil fuels and increasing the energy demand are the critical concerns for the sustainable growth of every country. These challenges highlight the need for a cleaner fuel globally. In particular, substituting the petroleum fuels with biofuels could significantly support sustainability. Hence, this study explores the impact of acetylene induction in a low heat rejection (LHR) diesel engine with ternary blend (TB) as a pilot fuel. TB includes 10%methanol + 20%WCOB + 70%diesel. During the dual fuel operation, the acetylene induction was varied (12, 18, and 24 lpm) with different pilot fuel combinations in a LHR engine. From the experimental results, it was revealed that brake thermal efficiency (BTE) is improved by 10.3% for TB with acetylene at 24 lpm and increased the exhaust gas temperature (EGT) by 10.3% at full load conditions. This study further evaluates the implementation of machine learning algorithms, namely, Random Forest regression (RFR) and Polynomial regression (PR) in predicting the performance parameters [BTE, brake-specific fuel consumption (BSFC), and EGT]. The results indicate that RFR outperforms PR in accurately predicting engine performance characteristics with a coefficient of determination R2 = 0.97, R2 = 0.98 for BTE, whereas for BSFC the R2 = 0.96, R2 = 0.95, and for EGT, the R2 = 0.95, R2 = 0.97 for the test fuels diesel and TBA3, respectively. These findings suggest that the combination of LHR technology, TB fuel, and acetylene can enhance engine efficiency and performance characteristics, and machine learning models can effectively predict these outcomes.

Co-optimization and prediction of high-efficiency combustion and zero-carbon emission at part load in the hydrogen direct injection engine based on VVT, split injection and ANN

Hydrogen fuel holds great promise for accelerating the energy sector's decarbonization efforts. However, hydrogen's unique properties pose challenges for hydrogen direct injection (HDI) engines, such as differences in airflow exchange capabilities for very low density and reduced combustion rates due to lean burn conditions. This study investigates the impact of combined variable valve timing (VVT) and split injection strategies on HDI engine combustion, efficiency, and emissions. Using Artificial Neural Network (ANN) models and experimental data, predictive models for Brake Thermal Efficiency (BTE) and Nitrogen Oxide (NOx) emissions were developed. Adjusting intake and exhaust valve timings improved BTE by up to 2.5 % and 1.8 %, respectively, while reducing NOx emissions by 48.9 % and 31.1 % under specific conditions. Optimizing split injection alongside VVT further increased BTE by 1.2 % and 0.9 %, but increased NOx emissions by 29.9 % and 26.5 %. The flexible application of VVT and split injection strategies aims to balance efficiency gains with emissions control. The ANN-based models demonstrated high accuracy (R2 > 0.974), proving reliable substitutes for real-engine testing in certain conditions. In conclusion, this research highlights the potential of VVT and split injection strategies to enhance HDI engine performance while mitigating environmental impact, supporting the transition to sustainable energy solutions.

Validation of methods for increasing the efficiency of detonation jet engines

Validation of methods for increasing the efficiency of detonation jet engines

The Quest for Industrially and Environmentally Efficient Nanobubble Engineering: Electric-Field versus Mechanical Generation Approaches

The Quest for Industrially and Environmentally Efficient Nanobubble Engineering: Electric-Field versus Mechanical Generation Approaches

Analysis and optimization of energy conversion for an on-board methanol reforming engine with thermochemical recuperation

Methanol steam reforming (MSR) is a promising method to address the storage and safety issues of hydrogen-fueled engines. This method can also significantly improve engine efficiency by recovering exhaust heat. Additionally, low temperature combustion technology can effectively mitigate the issue of excessively high NOx emissions in hydrogen internal combustion engines. However, research on the integration of low temperature combustion technology with methanol steam reforming is limited, and the design of reformers and strategies for methanol reforming remains underdeveloped. Therefore, a one-dimensional model of the methanol steam reforming engine system was established, and methanol reforming strategies were evaluated under varying engine loads. Further a multi-objective optimization of the reformer was conducted to balance system efficiency and economy. The results indicate that complete methanol reforming is unattainable at mid to high loads due to significant turbo work. A partial methanol reforming strategy, where part of the methanol is directly combusted in the cylinder and the rest is reformed to produce hydrogen, achieves the highest system efficiency. After multi-objective optimization of the reformer, this MSR engine yielded a 5.54% increase in average overall system efficiency under three loads, compared to not using thermochemical recuperation.

Modulating bacterial function utilizing A knowledge base of transcriptional regulatory modules.

Synthetic biology enables the reprogramming of cellular functions for various applications. However, challenges in scalability and predictability persist due to context-dependent performance and complex circuit-host interactions. This study introduces an iModulon-based engineering approach, utilizing machine learning-defined co-regulated gene groups (iModulons) as design parts containing essential genes for specific functions. This approach identifies the necessary components for genetic circuits across different contexts, enhancing genome engineering by improving target selection and predicting module behavior. We demonstrate several distinct uses of iModulons: (i) discovery of unknown iModulons to increase protein productivity, heat tolerance and fructose utilization; (ii) an iModulon boosting approach, which amplifies the activity of specific iModulons, improved cell growth under osmotic stress with minimal host regulation disruption; (iii) an iModulon rebalancing strategy, which adjusts the activity levels of iModulons to balance cellular functions, significantly increased oxidative stress tolerance while minimizing trade-offs and (iv) iModulon-based gene annotation enabled natural competence activation by predictably rewiring iModulons. Comparative experiments with traditional methods showed our approach offers advantages in efficiency and predictability of strain engineering. This study demonstrates the potential of iModulon-based strategies to systematically and predictably reprogram cellular functions, offering refined and adaptable control over complex regulatory networks.