Low-power Engine Research Articles

ПОВЫШЕНИЕ ДЛИТЕЛЬНОСТИ ПОЛЕТА БЕСПИЛОТНИКОВ СЕЛЬСКОХОЗЯЙСТВЕННОГО НАЗНАЧЕНИЯ

The analysis and review of methods for solving the problem of short flight duration of unmanned aerial vehicles (UAVs) for agricultural purposes is performed. The state of the issue of insufficient flight time and the need to charge drones to ensure full automation and continuity of the work process is studied. The main types and models of batteries used in UAVs as energy sources are characterized. The main methods of their refueling are considered in a comparative aspect. Particular attention is paid to the study of the advantages and disadvantages of technical solutions to the designated problem. Such methods as: using an automatic charging station for drones, designing drones called "flying batteries", using a laser and a high-power electromagnetic field are noted and described. A method for increasing the flight duration of a drone by installing a payload and a power source on an accompanying vehicle (TS) is proposed. It is recommended to provide a wired connection between the drone and the TS for charging the drone and refueling it with chemical liquids for spraying crops. The following advantages are noted: continuous power supply to the drone from the vehicle, increased duration of spraying without refueling with chemicals, the ability to perform various tasks by drones, no need for expensive drones due to the possibility of using low-power engines due to the location of power sources on the vehicle. To solve the above problem, an automated device for replacing UAV batteries is proposed, which will increase the flight duration. This device consists of two drums for batteries in which feed springs are installed, a control module, a drum shaft drive, and a platform for automatic drum change and battery charging.

GRB 211211A: The Case for an Engine-powered over r-process-powered Blue Kilonova

The recent gamma-ray burst (GRB) GRB 211211A provides the earliest (∼5 hr) data of a kilonova (KN) event, displaying bright (∼1042 erg s−1) and blue early emission. Previously, this KN was explained using simplistic multicomponent fitting methods. Here, in order to understand the physical origin of the KN emission in GRB 211211A, we employ an analytic multizone model for r-process-powered KNe. We find that r-process-powered KN models alone cannot explain the fast temporal evolution and the spectral energy distribution (SED) of the observed emission. Specifically, (i) r-process models require high ejecta mass to match early luminosity, which overpredicts late-time emission, while (ii) red KN models that reproduce late emission underpredict early luminosity. We propose an alternative scenario involving early contributions from the GRB central engine via a late low-power jet, consistent with plateau emission in short GRBs and GeV emission detected by Fermi-LAT at ∼104 s after GRB 211211A. Such late central engine activity, with an energy budget of ∼a few percent of that of the prompt jet, combined with a single red KN ejecta component, can naturally explain the light curve and SED of the observed emission, with the late-jet–ejecta interaction reproducing the early blue emission and r-process heating reproducing the late red emission. This supports claims that late low-power engine activity after prompt emission may be common. We encourage early follow-up observations of future nearby GRBs and compact binary merger events to reveal more about the central engine of GRBs and r-process events.

Power and efficiency improvement of SI engine fueled with boosted producer gas-methane blends and LIVC-miller cycle strategy: Thermodynamic and optimization studies

An appealing alternative solution for lowering both reliance on power grid and pollution is by adopting decentralized power generation using gasifier-engine integrated systems. However, the utilization of gasification-derived producer gas (PG) leads to low engine power output and efficiency as compared to conventional fuels. This pertains to its low Calorific value(CV) and low flame-speed. Therefore, this simulation study aims to simulate and investigate the improvements in these parameters by inspecting various boosted-intake pressures and blends of high-CV methane with PG as inputs along with the implementation of Late inlet valve close(LIVC)-Miller cycle strategy on a 1500 RPM Dual-fuel(DF) SI engine model. Quasi-dimensional thermodynamic modelling (QDTM) was applied to simulate this performance and emission investigation by considering Sewage sludge-based PG (SSPG) as the PG variant. Best operational input settings were found using the Response Surface Methodology(RSM)-based multi-objective optimization. These optimal inputs were 3 bars of Pressure at intake valve closure (PIVC), 76.94 % SSPG-blend, and 77.32⁰ (ABDC) LIVC. The responses were correspondingly predicted as 40.46 % ITE, 21.35 bars IMEP, 16.8 kW BP, 20.04 bars BMEP, 9.48 MJ/kWh BSEC, with 0.08 V% CO and 3094 ppm NO emissions. Finally, with the ANOVA-based analysis, a 0.712 composite desirability was achieved with 95 % confidence level.

Energy and Exergy Assessments of a Diesel-, Biodiesel-, and Ammonia-Fueled Compression Ignition Engine

The research is aimed at investigating ammonia in a compression ignition internal combustion engine as a promising alternative fuel towards decarbonization. This study presents energy and exergy assessments of a low-power engine for three cases of fuel supply, diesel oil, biodiesel oil, and ammonia with pilot biodiesel oil, across the entire engine’s range. While diesel or biodiesel was administered directly into the engine cylinder, the ammonia was delivered through port injection. The results show that the maximum thermal efficiency of 33.56% and exergy efficiency of 31.88% were found at 1800 rpm and 71% load for the diesel fuel system. For the biodiesel fuel system, the efficiencies were 32.72% and 30.93%, respectively, at 1800 rpm and 100% load, and for the ammonia with pilot biodiesel system, they were at 31.98% and 30.04%, respectively, for the same rpm and load. The exergy assessment indicates that exergy destruction, which accounts for the irreversibility of processes such as combustion and friction, is responsible for the greatest loss of useful energy. Optimizing these processes could significantly improve the engine’s performance for all three fuel cases. This research found that ammonia could successfully substitute diesel or biodiesel fuel, as the engine’s efficiency was comparable in all three tested scenarios; however, further research and optimization in terms of the ammonia-fueled engine emissions are required.

Optical study of oxygen enrichment on methane combustion characteristics under high compression-ratio conditions

Natural gas is a promising fuel for IC engines with low carbon emissions, whereas its poor lean combustion performance at low load and low engine power output at high load remain a challenge for automobile manufacturers. Oxygen-enriched combustion can provide more opportunities for collisions between fuel and oxygen molecules; thus, methane combustion performance can be improved. In this work, using a high-compression-ratio optical engine, the effects of oxygen enrichment on methane combustion were comprehensively investigated, addressing the similarities and differences between high load and low load conditions. High-speed direct photography and simultaneous pressure were performed to capture detailed combustion evolutions. The results show that high oxygen concentration can greatly increase methane flame propagation speed under high energy density condition (high load). As a result, advanced combustion phase and high peak pressure are obtained by more concentrated heat release, which in turn are indicators for improvised thermal efficiencies. Under low energy density condition (low load), oxygen enrichment mainly acts as a promoter of the initial flame formation, which in turn are indicators for improvised combustion stability. A detailed comparison of flame characteristics confirms the different effects of oxygen enrichment on methane combustion under different energy density conditions. Besides, oxygen enrichment can significantly promote initial flame formation with a higher rate and lower cyclic variation, and a low degree of oxygen enrichment can also have a great effect. The current study shall give insights into the strategies for oxygen enrichment on methane engines’ performance at different loads.

Effect of hydrogen direct injection on natural gas/hydrogen engine performance under high compression-ratio conditions

In traffic transportation, the use of low-carbon fuels is the key to being carbon-neutral. Hydrogen-enhanced natural gas gets more and more attention, but practical engines fueled with it often suffer from low engine power output. In this study, the inner mechanism of hydrogen direct injection on methane combustion was optically studied based on a dual-fuel supply system. Simultaneous pressure acquisition and high-speed direct photography were used to analyze engine performance and flame characteristics. The results show that lean combustion can improve methane engine's thermal efficiency, but is limited by cyclic variations under high excess air coefficient conditions. Hydrogen addition mainly acts as an ignition promoter for methane lean combustion, as a result, the lean combustion limit and thermal efficiency can be improved. As for hydrogen injection timing, late injection can increase the in-cylinder turbulence intensity but also the inhomogeneity, so a suitable injection timing is needed for improving the engine's performance. Besides, late hydrogen injection is more effective under lean conditions because of the reduced mixture inhomogeneity. The current study shall give some insights into the controlling strategies for natural gas/hydrogen engines.

Cycle-resolved visualization of lubricant-induced abnormal combustion in an optical natural gas/hydrogen engine

The carbon-free policies and the shortage of crude oil have made engines fueled with natural gas get more and more attention, but actual engines fueled with natural gas often suffer from low engine power output and thermal efficiency. Hydrogen addition and high boosting are effective ways to improve natural gas engines’ efficiency and power output, however, abnormal combustion may occur and prevent the further increase in engine performance. In this study, the inner mechanism of lubricant-induced abnormal combustion was studied based on an optical natural gas/hydrogen engine. The test fuel was chosen as M70H30 and the in-cylinder lubricant was achieved by smearing the piston with excessive lubricating oil. Simultaneous pressure acquisition and high-speed direct photography were used to study flame propagation and abnormal combustion processes. The results show that the lubricant-induced auto-ignition occurred randomly, while no knock occurs due to the low energy density of M70H30. Besides, the abnormal combustion is observed to be directly related to the retained hot spot, and an early auto-ignition always results in too much negative work and low thermal efficiency. Comparing the location of abnormal combustion, it is found that the effect of auto-ignition on combustion also strongly depends on the location of hot spots. Furthermore, the comparison between end-gas auto-ignition cycle and normal cycle implied that non-knocking end-gas auto-ignition is favorable for improving natural gas/hydrogen engines’ efficiency, because the heat release is more concentrated. The current study shall give insights into understanding the abnormal combustion in high-power natural gas/hydrogen engines.

Directions of Development of Adaptive Systems to the Operating Conditions of Mobile Wood Chopping Machines with Low Power Engines

Wood choppers shredding branches equipped with low power drive units (up to 10 kW) are characterized by low technical sophistication. Their work translates into the consumption of non-renewable energy sources and the emission of toxic exhaust compounds into the environment. There are innovative technical solutions that allow you to increase the efficiency of chopping machines while reducing environmental impact. Such systems improve the adaptation of chopping machines working conditions to the demand for the branch cutting process. The article characterizes the innovative speed control system of machines loaded periodically variable. The fuel consumption model was presented and referred to the pilot fuel consumption results of a prototype equipped with an adaptive system. Benefits and development directions of the tested systems have been demonstrated.

Analytical Model for the Design of Axial Flux Induction Motors with Maximum Torque Density

This article proposes a mathematical model of an axial flux induction motor (AFIM) with one stator and one rotor. The model is based on the expression for the electromagnetic torque, which presents a function of two independent variables: the axial length of the stator core and the flux density in the air gap. This allows calculating the main dimensions of the motor with the highest possible torque density. Thus, developed model is suitable for designing the motor of specified volume with maximum torque, and solving the inverse problem of minimizing the machine volume with the specified torque. The detailed output of the model and the results of the calculations for the low-power engine powered by voltage of 7.35 V (RMS) are given. The results are validated using FEM in ANSYS software: with the outer motor diameter of 0.11 m, the flux density in it reaches 1.2 T.

Operational and economic analysis of a Velox-type combined heat & power plant with a throttle valve

For many years, the Department of Power Engineering and Turbomachinery of the Silesian University of Technology has been using a small-capacity (about 500 kWe) steam-gas power plant. Based on many years of experience in operation of this power plant utilizing the Velox-type gas-steam system, an idea arose to modify this type of thermal power cycle to create a combined heat and power (CHP) plant of small capacity, dedicated for distributed heat and power production or production process steam with high temperature. Previous thermodynamic and economic analysis of that type of low-power CHP plant confirmed many advantages of using this type of solution in low-power engineering. The new idea is to add a throttle valve between the economizer and the evaporator for the reference cycle of the gas-steam Velox-type CHP plant. It was further assumed that water would partially be vaporized on the valve. This paper presents a thermodynamic and economic analysis of this type of a system with an added throttle valve. Downstream the valve, the evaporated water fraction is fed directly into the steam superheater. It is determined how such a retrofit affects the system thermodynamic and economic characteristics. The system is modelled in the EBSILON® Professional 14 software.

Impact of Number of Operators and Distance to Branch Piles on Woodchipper Operation

Branch chipping machines with low-power engines are distinguished with an intermittent operation due to a periodical supply of branches. A conventional drive speed control of these machines is not adapted to adjust the operating mode depending on frequency of material supply for shredding. This article discusses the issues related to the assessment of the application of adaptive systems similar in design to start–stop systems used in vehicles, as necessary in the driving of this type machine. During testing, an impact of a distance between a branch pile from the woodchipper, a number of operators on frequency of drive unit operating condition changes, and the mass and volume output (productivity) were considered. A percentage ratio of the active and passive (idle) operation in selected conditions of use was also determined. A low-power 9.5 kW engine-powered cylindrical-type woodchipper was used for testing. Material chopped in the chipper was freshly cut branches of oaks (Quercus L. Sp. Pl. 994. 1753) with a diameter in the largest cross-section ca. 80 mm and moisture content ca. 25%. Piles of branches were located at three different distances from the chipper, i.e., 3 m, 9 m and 15 m. Branches to the chipper were fed by one or two operators. It was demonstrated that the idle run time in tested conditions with one operator could be from 43% to 71% of the entire operating time. Frequency of operating condition changes when only one operator worked and fluctuated from ca. 6 to 2 times per minute. Increasing the number of operators from one to two had a slight impact on the frequency of operating condition changes (by ca. 7%) at the shortest distance from the chipper (3 m). However, at larger distances, the additional operator may increase the frequency of operating condition changes of the chipper by 77% for 9 m distance and 85% for 15 m distance. The mass and volumetric output of the cylindrical chipper in the most advantageous case is equal to 0.66 t/h and 3.5 m3/h, respectively. The increase of the branch pile distance from the chipper causes a drop in mass output by 32%, and volumetric output by 33.5%. The results of the tests confirmed the necessity for the development of low-power chipping machines designed for clearing operations rather than industrial production of biomass. A direction for development could be systems that adapt driving units to operating conditions, depending on a demand for the chipping process.

ATTAINING SIMULTANEOUS REDUCTION IN NOX AND SMOKE BY USING WATER-IN-BIODIESEL EMULSION FUELS FOR DIESEL ENGINE

This paper presents the study of water-in-biodiesel emulsions (WiBE) stabilized by surfactants with different hydrophiliclipophilic balance (HLB) on a single-cylinder diesel engine. The engine performance and exhaust emissions were compared against the base fuel biodiesel (B5 diesel) which contained 5% palm oil methyl ester (POME) in the diesel fuel, at a constant engine speed of 2000 rpm with different engine loads. 36 emulsion blends of B5 diesel mixed with 9%, 12% and 15% volume of water, HLB values of 6, 7, 8 and 9, and surfactant dosage of 5%, 10% or 15% by percentage volume of water added. The results exhibited 11.7% lower engine power with WiBE as compared to B5 diesel. It was also observed that WiBE produced higher in-cylinder pressure and heat release rate. WiBE with higher water content at high load condition produced up to 15.2% higher peak pressure with a significant reduction in both NOx and smoke opacity, while a moderate decrease in the exhaust temperature was recorded for WiBE. The research work proved that WiBE with 15% water content with optimum HLB value is capable of reducing up to 79% NOx and 23% smoke opacity simultaneously, due to the heat sink effect during combustion.
 Keywords: emulsified fuels, surfactant, microexplosion, exhaust emission, palm oil, heat sink effect

COMPARATIVE ANALYSIS OF THE ENERGY INDICATORS OF SINGLE-MOTOR AND MULTIPLE-MOTOR ASYNCHRONOUS ELECTRIC DRIVE

The aim of the work is to conduct a comparative analysis of single-engine and multi-engine asynchronous traction electric drive based on energy based on the assessment of energy losses in traction asynchronous electric motors of different power using the proportional law of frequency control to control the speed of traction asynchronous electric motors in the first zone. The energy loss analysis in traction asynchronous electric motors was carried out for three values of the voltage frequency on the stator winding 50 Hz, 25 Hz and 12.5 Hz and for three values of the total load moment corresponding to the full, half full and empty bus on the asphalt road. In determining the total load moment, the rolling resistance of the bus and the air resistance were taken into account. As a result of the analysis, a formula was obtained that allows, based on the power of constant and variable losses in compared electric motors corresponding to the nominal load moment, to determine the number of low-power engines that make up the multi-motor drive, which will provide the energy effect from the use of multi-motor electric - the drive instead of the singlemotor electric drive. In addition, energy losses in the traction asynchronous electric motors included in the single-engine and multi-motor electric drive during acceleration of a full and empty bus to a maximum speed of 12.5 seconds were evaluated. To estimate the losses in the compared electric motors at voltage different from the nominal value, mathematical modeling was used in the MatLab package. It is shown that the use of a multi-motor asynchronous electric drive allows to reduce energy losses in traction asynchronous electric motors when the vehicle is moving at a constant speed and during acceleration with a different number of passengers. Moreover, to obtain the energy effect, the number of engines used in a multi-motor electricdrive should vary depending on the speed and acceleration of the bus, as well as on the total load moment of the multi-motor drive.

Characterization of the Fine Particle Emissions from the Use of Two Fischer-Tropsch Fuels in a CFM56-2C1 Commercial Aircraft Engine.

The fine particulate matter (PM) emissions from the use of two types of Fischer-Tropsch aviation fuels and their 50:50 blends with military JP-8 were quantified as part of the first Alternative Aviation Fuel Experiment (AAFEX). Measurements were made at 30-m downstream of a CFM56-2C1 engine for PM mass and number, particle size distribution, black carbon (BC), and volatile PM (sulfate + organics) using selected on-line instrumentation. The PM number emission index (EI N ) ranged from ~ 2 × 1015 to 7 × 1016 particles/kg fuel burned depending on fuel flow, fuel composition, and sampling temperature with the magnitude of the emissions inversely correlated to fuel flow. The PM mass emissions (EI M ) measured in the study varied from ~ 5 to 680 mg/kg fuel again depending on fuel flow, fuel type, and sampling temperature with a characteristic U-shaped curve of EI M with respect to fuel flow observed from the data. At low fuel flow (corresponding to low engine power), particle number and volume size distributions contained a single mode whereas at higher engine power, a bi-modal distribution was observed. The BC emissions varied from ~ 3 to 415 mg/kg fuel depending on fuel type and were found to exponentially increase with engine power (fuel flow). The volatile PM varied with sample temperature, fuel type, and increasing fuel flow within the range of EIs from ~ 0.4 to 11 mg/kg fuel with the highest values being at low fuel flow. Finally, the use of the two neat alternative fuels reduced the EI N by a median value of 70-73% and the EI M by ~ 94% as compared to JP-8 across all power conditions tested.

Effects of late injection on lean combustion characteristics of methane in a high compression ratio optical engine

Energy crisis and environment pollution have made engines fueled with natural gas getting more and more attention, but practical engines fueled with natural gas often suffer from low engine power output and thermal efficiency. In this study, with addressing the role of late high-pressure injection, engine performance and flame propagation were studied in a high compression-ratio optical engine fueled with methane under lean combustion condition. First, the experiments with different excess air coefficients under two representative injection timing conditions were performed. The results show that with the increase of excess air coefficient, the indicated mean effective pressure (IMEP) is decreased. When the excess air coefficient is high, the combustion even becomes unstable under early injection conditions, which is due to the low flame speed. Second, different injection timings were employed under lean condition, and the results show that the combustion process is significantly affected by injection timing. Advanced combustion phase and higher heat release rate are observed under late injection condition. Finally, further analysis of flame images and pressure shows that late injection can increase the air intake quantity but also in-cylinder turbulence intensity. The highest flame speed is obtained under the latest injection condition with an increment above 50%, and flame propagation direction is also changed under different injection timings. Besides the compression pressure before spark is higher for late injection, meaning high volumetric efficiency. Therefore, late injection with high pressure is an effective way to improve the power output and thermal efficiency of natural gas engine.

A new methodology to optimize a race car for inertial sports

In sports competitions with wheeled vehicles, the resistances to movement that most affect vehicle performance are aerodynamic drag, rolling resistance, inertial forces and gravitational forces. When a powerful engine is available, the rolling resistance is negligible but, in competitions where the vehicle has a low-power engine or lack of it, the rolling resistance has a significant influence on the vehicle performance. The resistance to advance in curve due to the steer angle (curve resistance) is not taken into account during the design process. However, as noted in other research for this type of vehicle, the curve resistance cannot be neglected. Therefore, this article develops a methodology to optimize the vehicle cornering behavior of non-motored vehicles intended for inertial sports, which can be applied to any type of wheeled vehicle. The target of the vehicle optimization is to maximize its cornering speed, while its resistance to movement is reduced. As will be shown, both factors are related and opposed to each other.

COMPARISON OF BIODIESEL B-20 AND B-30 ON DIESEL ENGINE PERFORMANCES AND EMISSIONS

Biodiesel is renewable energy that is made from renewable sources such as vegetable oil (palm oil, soybean oil or jathropa oil) through a trans-esterification reaction. Biodiesel can be used as a substitute for diesel fuel or as a mixture with diesel fuel. B-20 and B-30 fuel are a biodiesel mixture with diesel fuel which contains 20% biodiesel and 80% diesel fuel and 30% biodiesel and 70% diesel fuel respectively. The aim of this study is to compare the performance tests of B-20 and B-30 on a diesel engine. Comparison of their performance comprises engine power, engine torque, specific fuel consumption (SFC) in various loads and emissions. Result shows that the B-20 and B-30 performance is affected by the chemical-physical characteristics of fuel, such as kinematic viscosity, cetane number, density and calorific values. Performance test results show that B-30 has 1.69% lower engine power and 0.62% higher SFC than B-20 at a full load condition. In contrast, B-30 has better emissions than B-20 with a 6.71% decrease in smoke opacity.

Diagnostics and evaluation of the residual life of an induction motor according to energy parameters

The various devices based on vibration, thermal, electromagnetic and other methods are used to diagnose an asynchronous motor today. The use of vibration diagnostics is common for large machines. The emergency stop of the large machines leads to significant downtime and non-produced products meaning that the enterprise incurs significant material losses. However, for low-power engines, vibration diagnostics are used only as a periodic assessment of the state without accumulation of data and their subsequent analysis. It should also be noted that the vibration signals measured from the rolling bearing are affected by varying operating conditions and noise that distort the signal and complicate the faults identification for further evaluation of the residual life. In a number of cases, such as submersible pumps, nuclear power plant safety aggregates, mining equipment, it is practically impossible to use vibration, thermal and other methods for diagnosing asynchronous motors. Therefore, the actual task of this research is the development of a method for diagnosing and estimating the residual life in conditions of the systems without any maintenance, based on the electric motor energy parameters.

Auto Drain Valve Water Separator inside the Unit of Komatsu HD 465-7R

Water separator is a component that separate water from fuel, so the circulating fuel in the fuel system is not contaminated by water. If there is water inside the water separator, it will be carried by into the fuel system and then impacting to the engine performance. It’s such as lowering engine power because the fuel filter is clogged due to the fuel mix with water. Then the real danger is in case of the fuel mixes with the water. It will damage the fuel system components such as blockage of injectors due to corrosion and wear of fuel supply pump. As informed from daily maintenance record data, we have found that the low power engine trouble was caused by the fuel filter that was clogged high enough. Using the fishbone analysis, we got the main problem is there was water in the fuel separator at maximum level and did not discharge. In this condition, it is need optional device to automatically discharge the water from the water separator while maximum level reached, so the operator does not need to drain the water manually. The operator will be warned by buzzing active alarm and flashing caution lamp inside the cabin. By this method, the potential risk of mix up water with fuel would be avoided and the loss of others component failure would be mostly avoided. By using this tool, we can save net quality income around IDR (Indonesia Rupiah) 11,673,519,800.

Nonintrusive Gas-Turbine Engine-Exhaust Characterization Using Acoustic Measurements

This paper reports exhaust measurements performed using a nonintrusive acoustic technique on a JT15D-1A turbofan research engine. Using multiple streamwise displaced microphones, the integrated exhaust velocity and static temperature were measured simultaneously in engine flows with bypass Mach numbers up to 0.48. A Kiel pressure and K-type thermocouple probe was used to assess the accuracy of the acoustic measurements. The Integrated velocity and static temperature rms errors of and 2.3 K were identified. Using probe-based measurements at a low engine power setting, two calibration constants were identified for conversion from integrated flow parameters to mass flow and thrust. Applying the calibration constants to the acoustic measurements, and 200 N rms errors in mass flow and thrust were observed. These promising results indicate that the acoustic technique may be used to characterize and monitor gas-turbine engine performance. To the authors’ knowledge, this is the first time a nonintrusive acoustic technique has been used to characterize engine flows with Mach numbers greater than 0.3.