Search

The present research work is an attempt to develop a dedicated biogas fuelled SI engine technology from a 100 cc motor cycle. Such a small engine is coupled with alternator especially suitable in remote rural electrification which is still not connected to grid line or has a limited access. The experimental work presents the performance results of a small 98 cc, single-cylinder, four stroke cycle gasoline engine which is optimized to run on scrubbed biogas (CH4 93.8%) and raw biogas (CH4 56.6%) with successive modifications to the engine and its components. The work is carried out in stages to develop a dedicated biogas engine technology. The various aspects like piston crown geometry and compression ratio (CR), is investigated in this research work to evaluate the performances using biogas as fuel and comparing the same with gasoline is also made with the results obtained during experimental tests. The tests were conducted at 3000 rpm using three pistons having different crown geometries and cleavage on its crown. The selected three pistons enable to study the significance of CR (in the range of 6–9) and piston crown geometry to achieve the optimal configuration. The experimental results have revealed that increase in CR in a close range of 8:1 with larger cleavage on piston crown geometry enhances engine performance for Biogas fuelled small S.I. engine 100 cc category. It has been observed during comparative analysis that the maximum power produced by the biogas fuelled engine has improved by 13.4%, BSEC has increased by 23.30% and there is an 18.18% improvement in BSFC.

The in-cylinder flow characteristics of a four-stroke, four-valve, pent-roof small engine of motorcycle at engine speeds from 2000 rpm to 4000 rpm were studied using computational fluid dynamics (CFD). The aim of this study was to investigate the in-cylinder flow characteristics of small engines, including tumble, swirl, turbulent kinetic energy (TKE), angular momentum, in-cylinder air mass, turbulent velocity, turbulent length scale, and air flow pattern (in both intake and compression strokes) under motoring conditions. The engine geometry was created using SolidWorks, then was exported and analyzed using CONVERGE, a commercial CFD method. Grid independence analysis was carried out for this small engine and the turbulence model was observed using the renormalized group (RNG) k-ɛ model. The pressure boundary conditions were used to define the fluid pressure at the intake and exhaust of the port. The results showed that the increase in the engine speed caused the swirl flow in the small engine to be irregularly shaped. The swirl flow had a tendency to be stable and almost constant in the beginning of the compression stroke and increased at the end of compression stroke. However, the increase of in engine speed had no significant effect on the increase in tumble ratio, especially during the intake stroke. There was an increase in tumble ratio due to the increase in engine speed at the end of compression stroke, but only a marginal increase. The increase in engine speed had no significant effect on the increase in angular momentum, TKE, or turbulent velocity from the early intake stroke until the middle of the intake stroke. However, the angular momentum increased due to the increase in engine speed from the middle of the intake stroke to the end of compression stroke, and the angular momentum achieved the biggest increase when the engine speed rose from 3000 to 4000 rpm by 10 % at the end of the intake stroke. The increase in engine speed caused an increase of TKE and turbulent velocity from the middle of intake stroke until the end of compression stroke. Moreover, the biggest increase of TKE and turbulent velocity occurred when the engine speed rose from 3000 to 4000 rpm at the middle of intake stroke around 50 % and 25 %, respectively. Turbulent length scales appeared to be insensitive to increasing engine speed, especially in the intake stroke until 490 °CA. From that point, the value of the turbulent length scale increased as engine speed increased. The biggest increase in the turbulent length scales occurred when the intake valve was almost closed (around 20 %) and the engine speed was within two specific ranges (2000 to 3000 rpm and 3000 to 4000 rpm). Regarding the effect of engine speed, there were no significant effects upon the accumulated air mass in the small engine. The increase in engine speed caused an increase of turbulence in the combustion chamber during the late stages of the compression stroke. The increase in turbulence enhanced the mixing of air and fuel and made the mixture more homogeneous. Moreover, the increase in turbulence directly increased the flame propagation speed. Further research is recommended using a new design with several types of intake ports as well as combinations of different intake ports and some type of piston face, so that changes in air flow characteristics in small engines can be analyzed. Finally, this study is expected to help decrease the number of experiments necessary to obtain optimized systems in small engines.

The problem of maintaining the flat parameters of the working orbit of a small spacecraft using an electric thruster is considered. In low working orbits, due to the Earth’s atmosphere, aerodynamic forces act on the spacecraft, which cause a decrease in the radius of the orbit and the end of the target functioning. The analysis of the time parameters of the cyclogram for maintaining the working orbit of a small spacecraft with an electric jet engine is carried out taking into account the variability of the atmosphere density. The cyclogram consists of sections of passive movement and active movement under the action of a small engine thrust. For the satellite under study, the thrust parameters of the electric jet engine were selected, which allow the correction of the plane parameters of a low orbit. Using the characteristics of the thrust and specific impulse of an electric jet engine, we calculated the fuel reserves for correction over a long period of time. The results of the analysis show that it is effective to use an electric jet engine in terms of fuel consumption for correction.

This research investigates the use of biogas to run a spark ignition petrol engine and test for the engine performance. Conventional spark ignition petrol engine was modified into a dual fuel engine by changing the engine single fuel carburettor to dual fuel carburettor. The air orifice was closed by 50% to enable cooled start with natural biogas as the low calorific value won't facilitate combustion. The speed, torque, and other engine parameters where measured using a TD200 small engine test set (hydraulic brake dynamometer) interface and emissions of SO2, CO were measured using an emissions analyser. The torque, brake power was higher petrol by 39% than the biogas due to the lower calorific value of biogas. The exhaust temperature, SO2 and CO was 49% lower for the biogas than the petrol. The comparative analysis of the modified engine showed that petrol can be substituted partly with biogas and the engine used for varying applications because it offers window escape on the hydrocarbon reservoir depletion, green gases emission from the use of these petrol and landfill emission as well.

This paper presents a study of residual gas, effective release energy and engine emissions of small engine with variable ignition timing at full load. The study was conducted by simulating the variable ignition timing from 10 to 40 degrees in the full-load operation mode at low speed (3000 rpm), medium speed (5000 rpm) and high speed (8000 rpm) of the engine, then comparing the changes of the residual gas, exhaust gas (NO x , CO, HC) and effective release energy. The results from the simulation showed that the ignition timing had a significant effect residual gas ratio, effective release energy, engine performance, and emission characteristic. When the engine speed at high speed and ignition timing is 10 °CA, the minimum residual gas ratio was 0.07%. At the ignition timing is 40 °CA, the maximum effective release energy was 0.87 kJ. Moreover, at the engine speed at low speed the maximum release energy was 0.635 kJ at 10 °CA of ignition, while the high speed achieved maximum release energy at 40 °CA was 0.848 kJ. The maximum engine brake torque was 20.37 Nm and the minimum BSFC was 334 g/kWh at medium speed and 30 °CA of ignition timing.

Pollutant emission of vehicle cars is nowadays a fundamental aspect to take into account. In the last decays, the company have been forced to study new solutions, such as alternative fuel and learn burn mixture strategy, to reduce the vehicle's pollutants below the limits imposed by emission regulations. Pre-chamber ignition system presents potential reductions in emission levels and fuel consumption, operating with lean burn mixtures and alternative fuels. As alternative fuels, methane is considered one of the most interesting. It has wider flammable limits and better anti-knock properties than gasoline. Moreover, it is characterized by lower CO2 emissions. The aim of this work is to study the evolution of the plasma jets in a different in-cylinder conditions. The activity was carried out in a research optical small spark ignition engine equipped alternatively with standard ignition system and per-chamber. The engine runs at 2000 rpm at wide open throttle in standard ignition condition and slightly turbocharged in pre-chamber condition in order to overcome the decrease of compression ratio. In this activity methane and gasoline were used. Methane was always injected in the pre-chamber and ignited by spark plug; meanwhile gasoline was injected in the main chamber by port fuel injection mode. The combustion of the pre-chamber methane mixture generates four plasma jets that quickly ignite the mixture made with gasoline/air into the combustion chamber. In this condition the flame speed was much faster than the traditional ignition (gasoline injected in intake manifold without prechamber). Using optical data, significant information about the flame propagation in terms of the speeds and radius were obtained. The optical data were correlated with the engine performance and indicated measurements that showed an increase indicated mean effective pressure and coefficient of variation reduction when the pre-chamber was used. Furthermore the effect of pre-chamber ignition on the engine stability and efficiency in stoichiometric and lean-burn operation conditions was investigated.

Studies on the correlation between ethanol-gasoline blends and pollutant emissions of small engine motorcycles are scant. This study examined the effects of ethanol-gasoline blends, containing various ethanol contents, on air pollutant emissions from two four-stroke fuel-injection motorcycles without engine adjustment. Three test blends, separately containing 15 (E15), 20 (E20), and 30 vol% (E30) ethanol in gasoline, were used to power the test motorcycles. Commercial unleaded gasoline was used as the reference fuel (as RF). The motorcycles were tested on a chassis dynamometer by using the Economic Commission for Europe test cycle. The target pollutants investigated in this study included criteria pollutants, volatile organic compounds (VOCs) and six species of organic air toxics. The results revealed that the emissions of CO, THC, total VOCs, alkanes, alkenes, and aromatic groups reduced when the ethanol-gasoline blends were used to fuel the motorcycles. E30 demonstrated approximately 1.2-fold increases in carbonyl group emissions compared with RF. Emissions of the target air toxics demonstrated a reduction potential on benzene, toluene, ethylbenzene, and xylene (BTEX), but increased the emissions of formaldehyde and acetaldehyde by 65% and 330%, respectively. Results also showed that the emission changes from fuel-injected motorcycle were generally smaller than the value of carburetor motorcycle. Fuel injection engine fueled with ethanol-gasoline blends may lead to emission reductions to CO, THC, and BTEX.

The airflow in the engine cylinder is known to greatly affect the performance of the engine. Therefore, the main objective of this study is to evaluate the flow characteristics of the in-cylinder small engine to see the effect of the intake port configuration at equivalent rated engine speed using simulation model under various intake valve lift conditions. Geometry engine created using CAD software, then exported and analyzed using CONVERGE. The turbulence model is observed using a modified model (RNG) k-ɛ. The pressure boundary conditions are used to determine the pressure fluid at the intake and exhaust port. The result shows that the change combination of the intake port give effect to swirl ratio value. The helical intake port with same direction have the highest swirl ratio during intake and compression stroke around thirteen times compare to the original model in valve lift maximum. The change combination of the intake port also give effect to the tumble ratio where the maximum tumble ratio occurs at the helical port with same direction where the maximum increase at 460 °CA around 83 % and the minimum tumble ratio occurs at helical port with opposite direction where the maximum decrease at 460 °CA around 83 %. The change combination of the intake port also give effect to increase the turbulent kinetic energy where the maximum increase around 300 % for model with same direction and 240 % for model with opposite direction and length scale also increase 35 % for model with same direction and 40 % for model with opposite direction. Finally, it is concluding that the analysis carried in this work is useful in predicting the flow and in-turn optimizing combustion chamber of the engine.

The transformation of a standard 4-stroke cylinder head into a torque-improved and gradually more efficient 2-stroke design is discussed. The concept with an effective loop scavenging via an extended inlet valve holds promise for engines at low- to medium-rotational speeds for typical designs of conventional 4-stroke cylinder heads. Calculations, flow simulations, and visualizations of experimental flows in relevant geometries and time scales indicate feasibility, followed by a small engine demonstration. Based on presumably long-forgotten and outdated patents, and the central topic of this contribution, an additional jockey rides on the inlet valve&rsquo, s disk (facing away from the combustion chamber) and reshapes the in-cylinder flow into a reverted tumble. A quick gas exchange with a well-suppressed shortcut into the open exhaust is approached. For overall mechanical efficiency, the required charge pressure for scavenging is of paramount importance due to the short scavenging time and the intake&rsquo, s reduced cross-section. Herein, still acceptable charging pressures are reported for scavenging periods equivalent to low or medium rotational speeds, as characteristic for heavy-duty applications. Using widely available components (charger, direct injection, variable camshaft angles) an increased engine efficiency is suggested due to the 2-stroke&rsquo, s downsizing effect (relatively less internal friction as well as the promise of more torque and a decreased size).

Climate change and increased demands for energy, tends the researchers to search for environmental friendly resources of alternative fuels that can be used in internal combustion engines. There are many types of existing alternative fuels that can be used in internal combustion engines, but the fundamental information about their combustion process is still limited. This study focus on the performance of methane fueled engines in a small spark ignition gasoline engine. The engine performance was measured on the brake torque, brake power, brake mean effective pressure (Bmep) and in-cylinder peak pressure. A Modenas Kriss 110cc gasoline engine was selected for experimentation and engine modelling. The 3D engine model was created using CATIA and the engine performance simulation was performed using GT-Suite v7.4.3. The engine performance results for the methane fueled engine were found to be lower at about 20.1% for engine torque, brake power and bmep and 12.0% for in-cylinder peak pressure when compared to the gasoline engine. From these results it can be concluded that the methane fuel can be used as an alternative fuel but it produces lower engine performance compared to a gasoline engine.

This paper presents the results of an investigation on the performance characteristics of a small spark ignition (SI) engine fueled by liquefied petroleum gas (LPG) to be compared with gasoline fueled. The LPG delivery systems used was fuel injection while carburetor was used for gasoline. In the experiment, wide open throttle (WOT) was run on a four stroke single cylinder engine that was coupled to a 20 kW generator dynamometer to measure the engine performance such as engine torque, and fuel consumption. Others parameters included are brake power (BP), brake specific fuel consumption (BSFC) and brake thermal efficiencies (BTH). The results were compared, analyzed and suggestions were made for modification for further improvement of using LPG in a small SI engine. It was found that the engine fueled by LPG had a lower performance compared to the gasoline fueled engine.

Using natural gas for fueling a ship growing extensively since environmental issues become one of the priorities in the shipping industry. The ship uses natural gas as the main fuel commonly called as a gas-powered ship. Gas has lower specific prices compare with any type of diesel fuel. But due to handling, storage, and distribution costs then gas prices for ships become higher even still a bit cheaper than diesel fuels. Besides prices, technically gas is cleaner so it may give the lower emission levels. Dual fuel technology is the best choice in occupied gas as ship fuel due to the existence of the IGF Code. Established Dual-fuel diesel engine is very expensive and available for big power capacity. This research develops a small dual-fuel diesel engine from a conventional engine with power less than 10 HP. The piston crown is a part of the engine that was modified so that the engine can use natural gas in the best performances as the conventional one. NOx as the most hazard emission in the diesel combustion process is controlled to be as the lowest as possible. The quality of air may be significantly affected by those small engine pollutions because of the large number of vessels in that dense environment in the typical fishery villages. In conclusion, the modified dual-fuel diesel engine capable of reducing NOx emission by up to 31% at a practical safe operation of 50% dual-fuel. The higher gas portion gives a lower NOx emission level.

Periodic change of engine lubrication oil is essential to maintain the health and longevity of an engine. The most common practice for motorcycles is to have an oil change at every 3000km interval. This study was done to analyze different base of engine oils between different engine oil brands by comparing its physical properties, namely density and viscosity. Three grades of commercially available lubricant oil for small motorcycle engines were tested: mineral (15W-40), semi-synthetic (10W-40) and fully-synthetic (5W-40). The oils were tested according to ASTM D 445 and D 1298, in its fresh state straight from the bottle, and after 3000 km mileage run in twelve 150cc 4-stroke single cylinder motorcycle engines. The test results showed that the density of engine oil samples increased while the kinematics viscosity decreased after the 3000 km mileage run. Different level of changes were recorded for different lubrication oil grades. Six out of twelve oil samples were found to have viscosity values (measured at 100oC) lower than the SAE J300 specification after the 3000 km mileage.

Both energy consumption and the ecology of mobile wood-chipping machines are important issues in forest management. One way of improving the efficiency of wood-chippers is to use innovative design solutions in drive unit control systems. This can result in a reduction in fuel consumption and quantitative exhaust gas emissions. This article presented the results of research conducted on the fuel consumption of a cylindrical wood chipper driven by a small engine. We carried out testing of the unmodified chipper (A), made two different chipper modifications (B) and (C), and tested the modified versions to achieve the indicated results. The process allowed analysis and comparison of recorded data. For this purpose, the engine was supplied with fuel in three different ways: carburetor (factory-made) (A), the injector (B), and injector with an adaptative drive control system (designed by the authors) (C). The construction of a maintenance-free and adaptive drive control system where its functioning depended on operating conditions was done following patent application P.423369. All three fuel supply systems: A, B, and C were tested experimentally in terms of fuel consumption. The research was conducted in both set exploitation conditions (idle work with high (1) and low (2) rotational speed, with a continuous chipping process (3)) and transient exploitation conditions (4) (resulting from the delivery time of wood waste). Thus, the first stage of research involved two constructions (A, B) for three different working conditions (1-3). The second stage consisted of three constructions (A-C) tested in the fourth working conditions (4). The tests showed that the injection system reduced fuel consumption by around 61% during the continuous chipping process in comparison with the carburetor system. The adaptive drive control system (C) reduced fuel consumption by 55&ndash, 74% in comparison with the carburetor system (A), and by 24&ndash, 60% in comparison with the injection system (B) without an adaptive drive control system. The level of energy consumption in these systems depended directly on the ratio of idle work time during the chipping process.

Biogas, as a renewable energy carrier, represents one of the possible biofuels which can be further used in firing processes with applications in both thermal and electrical processes. In Europe and worldwide there are developed methods used to capitalize this biofuel relative to its potential use in automotive applications. Romania still has a large gap to cover in terms of using its own biodegradable resources in order to produce suitable biofuels at large scale. With interest relative to this field, the present study involves applications of biogas produced by a pilot installation located at the Mechanical Engineering Faculty Multifunctional Laboratory, Politehnica University, Timisoara, using a moto-generator test rig in order to determine its suitability as a biofuel in small engine applications. The biogas was used as a standalone biofuel for the presented scenarios and the main parameters determined during the tests were: the specific consumption function of injection time, power as a function of injection time, the specific consumption function of advance to spark ignition and emissions of CO and CO2.

Scaled model experiments would be very effective in reducing cost, time and energy consumption in marine diesel engine development, however, relevant researches are rarely reported. The aim of this paper is to explore the potential of scaled model experiments for marine low-speed diesel engines, and provide references for researchers who attempt to conduct scaled model experiments in marine diesel engine development. At first, the computational fluid dynamics simulation model is established and calibrated against the experimental data from a marine low-speed diesel engine with 340 mm bore diameter. Then, three scaling laws for spray mixture formation and combustion processes as well as pollutant emissions are numerically studied with the baseline 340 mm-bore engine and an up-scaled 520 mm-bore engine at various injection timings. The results reveal that the spray mixture formation processes, in-cylinder temperature and pressure traces, and indicated thermal efficiency can be well scaled between the 340 and 520 mm-bore engines, while the three scaling laws show different degrees of similarity in soot and nitrogen oxides emissions. The increased heat transfer losses of the small engine are identified as a major obstacle to achieve the overall similarity, and the wall temperature setting methods to scale the heat transfer loss are theoretically derived and numerically verified. With the sophisticated control of the cylinder wall temperatures of the small engine, the discrepancy in soot and nitrogen oxides emissions between the large and small engines is reduced.

In this study performance characteristics of ammonia engines using direct injection strategies are investigated. Ammonia is a carbon-free fuel, and thus its combustion does not produce carbon dioxide, a critical greenhouse gas. Ammonia can be produced by using renewable energy sources (e.g., wind and solar) and used as an energy carrier. Recent research also has shown that the efficiency of solar thermochemical production of ammonia can be increased by combining the ammonia solid-state synthesis cycle with hydrogen production. Ammonia is under consideration for a potential storage method for wind energy. Ammonia's nature as carbon-free and its ability to be renewably produced make it an alternative to fossil fuels. In this study two direct injection strategies are tested and performance data, and exhaust emissions are recorded and analyzed. The first strategy tested liquid direct injection in a compression-ignition (diesel) engine utilizing highly advanced injection timings. Ammonia was used with dimethyl ether (DME) in a duel fuel combustion strategy. Ammonia was mixed with DME prior to injection. DME was chosen as a diesel substitute for its close fuel properties to ammonia. Three ammonia-DME ratios were tested: 100%DME, 60%DME-40%NH3, and 40%DME-60%NH3. Engine speeds of 1900 rpm and 2500 rpm were used based on the operational capability of 40%DME-60%NH3. Operation at 40%DME-60%NH3 required injection timing ranging from 90-340. Highly advanced injection timings resulted in homogeneous charge compression ignition combustion (HCCI). Cycle-to-cycle variations were reduced with increased load. NOx, NH3, CO, CO2, and HC were reduced with increased load for 40%DME-60%NH3. Low temperature combustion from low in-cylinder temperature from ammonia vaporization resulted in low NOx emissions meeting EPA emissions standards for small engine operation. The second strategy tested gaseous direct injection of ammonia in a spark-ignition (gasoline) engine. A CFR engine was operated at idle using the existing gasoline port injection system. Ammonia was directly injected using a solenoid injector. A ruthenium catalyst was implementing to partially decompose ammonia into hydrogen. Testing was performed over a range of seven performance modes using gasoline, gasoline-ammonia, and gasoline-ammonia with ruthenium catalyst. Injection timings of 270, 320, and 370 BTDC were used. Gasoline-ammonia showed little improvement in break specific energy consumption and CO2, and exhibited increased levels of NOx and HC over performance modes using gasoline only. Due to ammonia's low flammability limits and slow flame speed combustion efficiency was reduced. With the ruthenium catalyst Improvements in flywheel power were seen over performance modes without catalyst. The peak in-cylinder pressure was increased, and the start of ignition was advanced over both gasoline-ammonia and gasoline only performance modes. There was a significant reduction in NOx and NH3 present in the exhaust. Hydrogen present in the fuel increased combustion efficiency due to…

Table 1 shows the wide variety of applications for diesel engines and their characteristic figures. No other type of heat engine offers an equivalent range of power outputs. The engines are categorised according to their speed and application and, therefore, also their size and power output. The smallest category of large engines consists of heavy-duty vehicle engines with a capacity per cylinder of 1.5 l or more. However, many people regard large engines as starting at a capacity per cylinder of 2.5 l. There are four categories of large engine: — engines for heavy-duty road vehicles and industrial and stationary engines: heavy-duty engines — engines for fast ships, locomotives, rail cars and heavy construction vehicles: high-performance diesel engines — medium-speed four-stroke diesel engines (two-stroke engines no longer play a role in this market segment) for marine applications and diesel-powered heat and power stations, some of which can be used with heavy oil — slow-speed two-stroke diesel engines for direct drive applications in maritime industries. MTZ focused on different engine sizes on the basis of the interest at the time from the fields of scientific research and industrial development. Figure 1 shows the number of articles on the individual engine segments. Initially the emphasis was on large engines for ships and locomotives. Stationary engines were a constant theme across all the different periods. However, in the last 20 to 30 years, the majority of MTZ articles have concerned diesel engines for commercial vehicles and cars. The introduction of the ATZ-Offhighway and MTZindustrial magazines have resulted in fewer pieces appearing in MTZ about engines for construction vehicles, marine applications and stationary machinery. It is not always possible to categorise the individual articles by engine size, which means that the figures only give a general overview. TABLE 1 Specific values from different diesel engines (© Helmut Tschoke) Engine \ Parameter Speed [rpm] Power [kW] Specific power [kW/dm3] Power per cylinder [kW/cyl.] Engine displacement [dm3] Number of cylinder [−] BMEP [bar] Small engine 3000 – 3600 1.5 – 12 7.5 – 14 1,5 – 12 0,2 – 0,85 1 3 – 5 Passenger cars 3000 – 4600 35 – 283 40 – 95 17 – 40 0,8 – 4.2 2 – 8 17 – 22 LD vehicle 3000 – 4000 70 – 160 40 – 66 17 – 32 2 – 3.2 4 – 5 12 – 15 HD vehicle 1400 – 2500 170 – 600 20 – 35 29 – 67 7.7 – 16.4 5 – 8 12 – 28 High speed / high performance 1100 – 2200 500 – 10,000 25 – 55 120 – 500 30 – 350 8 – 20 23 – 30 Medium speed 300 – 1200 550 – 21,600 8 – 22 100 – 2000 25 – 2300 4 – 20 22 – 28 Two-stroke low-speed 70 – 170 4300 – 87,000 1.1 – 3.2 870 – 6200 750 – 29,000 5 – 14 18 – 22 Open image in new window FIGURE 1 Number of MTZ reports per year for different diesel applications (© Helmut Tschoke) Using the example of commercial vehicle engines in Figure 2, it becomes clear that the capacity has essentially remained consistent over the years, while the power has increased six- to eightfold and the torque by a factor of seven because of the widespread use of turbocharging. Figure 3 shows the mean effective pressures for all engine sizes. The medium-speed and high-performance diesel engines have the highest mean pressures at over 25 bar. The data in Figure 3 and Figure 4 come from different sources within MTZ and do not cover every engine application. They are only intended to indicate trends. Open image in new window FIGURE 2 Displacement, power output and torque of truck engines — sources: [28] and own inquiry (© Helmut Tschoke) Open image in new window FIGURE 3 Trend curves of BMEP for different diesel engines (© Helmut Tschoke) Open image in new window FIGURE 4 History of diesel engine development (© Helmut Tschoke)

Producer gas from biomass gasification is expected to contribute to greater energy mix in the future. Therefore, effect of producer gas on engine performance is of great interest. Evaluation of engine performances can be hard and costly. Ideally, they may be predicted mathematically. This work was to apply mathematical models in evaluating performance of a small producer gas engine. The engine was a spark ignition, single cylinder unit with a CR of 14:1. Simulation was carried out on full load and varying engine speeds. From simulated results, it was found that the simple mathematical model can predict the performance of the gas engine and gave good agreement with experimental results. The differences were within ±7%.

This paper describes the outcomes of a study carried out on a novel exhaust energy recovery system for a heavily downsized gasoline engine. The investigation was carried out based on a 1.0 L turbocharged gasoline engine offering the same performance as a 2.0 L model, with the aim of reducing CO2 emissions from 169 g/km to 99 g/km. This is to be obtained by the synergistic application of electrified boosting, stop/start technology, regenerative braking, torque assist and exhaust energy recovery systems. The research focussed on the design of a high performance LPT (Low Pressure Turbine) to recover latent energy left in the exhaust gas after expanding in the main turbocharger turbine. The LPT is meant to be coupled to an electric generator whose combination is usually referred as electric turbocompounding. Given the small engine size and therefore the low mass flow rate of the exhaust gas, the design operating conditions were fixed at 50,000 rpm with an optimum pressure ratio of PR ≈ 1.1. Commercially available turbines are not suitable for this purpose due to the very low efficiencies (less than 40%) experienced when operating in such low pressure ratios range. The design was accomplished by following a number of steps which go from meanline loss model development, full 3-D CFD (Computational Fluid Dynamics) analysis (using ANSYS CFX), prototype manufacturing and steady-state testing. The test results, that were conducted by using the Imperial College London cold-flow test facility, showed good agreement with CFD analysis with an efficiency greater than 70%. The steady maps obtained from testing were then input into a 1-D engine model including the electric turbocompounding. Three different arrangements were considered for the turbocompounding: (1) pre-catalyst, (2) post-catalyst and (3) in the wastegate of the main turbocharger. Two different scenarios were investigated in which the extra energy recovered by the turbocompounding unit is either fully regenerated into the engine crankshaft or stored and not re-used. The BSFC (brake specific fuel consumption) and the BMEP (brake mean effective pressure) were calculated and compared with the baseline engine under full and part load conditions. At full load, the analysis was performed for several engine speeds (from 1000 rpm to 6000 rpm at steps of 500 rpm each). The results showed that the extra energy recovered by the turbocompounding device is offering a significant benefit on engine performance; the post-catalyst solution offers the best compromise in terms of BSFC and BMEP with an improvement of 2.41% and 2.21% respectively. At part load engine instead, the analysis was performed for three engine speeds (1500 rpm, 2000 rpm and 4000 rpm) for the post-catalyst position only. Despite the increment in pumping work due to the presence of the LPT, no significant penalty in BSFC was calculated when no energy is returned into the engine whereas an improvement of ≈2.64% was found in the other case.

Liquefied Petroleum Gas (LPG) has become an interesting topic in the automotive industry to develop the engines with clean emission characteristics. The usage of gasoline as a fuel to power up the vehicle will contribute to the heavy environmental problem. A single cylinder four-stroke spark ignition (SI) engine that fueled by LPG and gasoline are used to predict and analyze the combustion process in the cylinder. A zero dimensional models are most suitable analytical models for engine cycle simulation. The simulation program has been developed using MATLAB software by implementing a single-zone thermodynamic model. The first law of thermodynamics is applying into this model and Annand's model was used to compute the convection and radiation of heat transfer within the cylinder. The engine performance parameters computed including the in-cylinder pressure, gas temperature, net heat release, mass fraction burn, brake power, torque, indicated specific fuel consumption. Then, exhaust emission in the cylinder was predicted by the formation of emission model. The results of engine performance are compared between gasoline and LPG as a fuel. Results show LPG engine has contributed to the lower HC and NOx emissions compared to gasoline. It proved that the development of simulation program is useful to calculate the engine performance at different operating points.

Two-blade aircraft propellers, designed to be powered by a small engine, were improved with engines used in three-blade aircraft propellers. As a consequence, the new engines revealed pressure losses, crack formation, and recurrent fracture, approximately after every 600 h of flight. This paper analyzed one of the failed engines; the engine has six cylinders manufactured in aluminum alloy. Optical microscopy and scanning electron microscopy were used for microchemical and microstructural analyses. Cracks were identified by using liquid penetrant between two cooling fins in the exhaust port and around the exhaust port, at the exhaust valve seats. Shrinkage micropores were found in the aluminum alloy forming cracks in the exhaust port.

Due to the fact that it is generally difficult to accurately calculate the nonlinear section of flow characteristics curve of small injection pulse width of electronic control injector, it is impossible for electronic control unit (ECU) to accurately control fuel injection quantity when the small engine such as motorcycle is under a working condition of idle speed or small load. This paper introduces the principle and method to make a fitting for flow characteristics of nonlinear section in the developed software system in details. Take the electronic control injector of motorcycle as an example, the programming method combined with LabVIEW and MATLAB is utilized to make a fitting treatment for accurate fuel injection quantity obtained via measuring single-chip microcomputer through Smoothing Spline method, so as to obtain the flow characteristics of small injection pulse width and normal injection pulse width of electronic control injector of motorcycle.

While considerable effort has been devoted in recent years to building miniature heat engines, relatively little attention has been paid to understanding how their performance changes with engine size. This paper presents scaling rules for the performance of miniature two-stroke piston engines that are candidates for battery replacements in miniature unmanned vehicles and man-portable electronic systems. In so doing, it quantifies the current state of the art in small engine performance and provides a means to estimate a minimum thermodynamically sensible length scale for a two-stroke engine. The scaling rules are derived from comprehensive dynamometer investigations of nine of the smallest commercially available internal combustion engines. Engine mass ranges from 15 to 500 g, displacement ranges from 0.16 to 7.5 cm3, power outputs range from 8 to 650 W, and overall efficiency ranges from 3 to 12%. Peak torque, power, and normalized power follow power law scaling relationships with engine displacement. ...

This paper presents outcomes of the usage of a developed prototype of PFI retrofit-kit for small 4-stroke gasoline engine. The developed PFI retrofit-kit produced good and high brake power and brake mean effective pressure compared to the carburetor system with over 50% improvement. Exhaust-out emissions such as carbon monoxide, carbon dioxide and hydrocarbon have been reduced in the range of 39%, 185%, and 57% respectively. However, brake specific fuel consumption was found to be higher (125%) as compared to carburetor system.

A small scale traveling wave or Stirling thermoacoustic engine with a resonator of only 1 m length was designed, constructed and tested by using nitrogen as working gas. The small heat engine achieved a steady working frequency of 45 Hz. The pressure ratio reached 1.189, with an average charge pressure of 0.53 MPa and a heating power of 1.14 kW. The temperature and the pressure characteristics during the onset and damping processes were also observed and discussed. The experimental results demonstrated that the small engine possessed the potential to drive a Stirling-type pulse tube cryocooler.

Small internal combustion engines, particularly those ranging in power from 1 kW to 10 kW, propel many remotely piloted aircraft (RPA) platforms that play an increasingly significant role in the Department of Defense. Efficiency of these engines is low compared to conventional scale engines and thermal losses are a significant contributor to total energy loss. Existing thermal energy loss models are based on data from much larger engines. Whether these loss models scale to the engine size class of interest, however, has yet to be established. The Small Engine Research Bench (SERB) was used to measure crank angle resolved gas temperature inside the combustion chamber of a small internal combustion engine (ICE). A 55 cc, twostroke, spark-ignition ICE was selected for this study. The engine was modified for optical analysis using sapphire rods 1.6 mm in diameter on opposite sides of the combustion chamber. The engine modification was found to have no measurable impact on indicated mean effective pressure or heat rejection through the cylinder. FTIR absorption thermometry was used to collect mid-infrared absorption spectra. The FTIR was allowed to scan continuously while simultaneously recording the scanning mirror position and crank angle associated with each data point, then data was re-sorted by crank angle. Measured spectra were compared with lines generated using CDSD-4000 and HITEMP line list databases. The line of best fit corresponded to the mean gas temperature through the combustion chamber. In this way temperature was determined as a function of crank angle for three operating conditions: 4,300, 6,000, and 7,500 revolutions per minute, all at wide open throttle. High cycle-to-cycle variation in the regions of combustion and gas exchange degraded temperature measurements at the affected crank angles. Future research will attempt to improve signal to noise in these measurements.

Small displacement, single cylinder engines with spark ignition are used as a low cost propulsion in many applications like scooters, motor cycles, small boats and handheld power tools. These engines follow two- or four-stroke principle and are usually realized with a carburetor. They represent an affordable and simple as well as durable propulsion technology, but concurrently their efficiency is low and emissions are high. Consequently, the share of these small engine applications of total emissions and fuel consumption is not negligible. Therefore, the demand to increase efficiency of these engines is rising and the development of suitable and cost efficient methods is required.

Most motorcycles in developing countries use carburetor systems as the fuel delivery method especially for models with the cubic capacity of less than 125cc. However, small gasoline fuelled engines operating using carburetor system suffer from low operating efficiency, waste of fuel and produce higher level of hazardous emissions to the environment. In this study, an electronic control unit (ECU) is designed and simulated for a retrofit fuel injection (FIS) system. The ECU is targeted to have a simple design, reliable and offers all of the necessary functions of the modern ECU. The simulation results shows that the designed ECU can determine the injection period as close to the proposed value and can drive the injector efficiently based on the generated PWM pulse.

With the continuous improvement of aviation engine performance, the engine rotor’s working speed is above the first critical speed, and some small engine rotor’s operating speed exceeds the second critical speed, thus most of the aircraft engine rotor is now flexible rotor. The primary goal of this research is to provide a new method without trial weights for flexible rotor balancing, which is based on the traditional modal balancing method and combines the dynamic characteristics of the rotor, such as the model shape, obtained by using finite element analysis software, the critical speed, the modal damping ratio, and so on. To demonstrate the validity and accuracy of the new method, two experiments are carried out. One is on a four-disk simply supported structure rotor experiment, which is balanced by using three balancing planes. After balancing the amplitude of the rotor through the first critical speed is reduced 80%. The other is on a turboshaft engine power turbine rotor which had been balanced quite well. The initial amplitude of the turboshaft engine power turbine rotor is 0.05 mm when it rotates at low speed, and the maximum amplitude is just 0.12 mm when it rotates at the first critical speed. After balancing the amplitude of the rotor through the first critical speed is reduced to 0.06 mm. The results of the experiments indicate that the new without trial weights method is a significant effective method for the flexible rotor dynamic balancing, and it will be widely used to balance the engine rotor.

The Semi-Direct Injection (SDI) system has been shown to improve small engine efficiency and exhaust by utilizing a lean burn method. In order to better understand how to more readily utilize the control systems in SDI engine, the real-time operation of an SDI engine was modeled. A charging model was developed by using a filling-and-emptying model to simulate air exchange in an engine, including varying the intake manifold structure. A single-zone model was applied to a combustion model and the effects of air/fuel ratio and swirl ratio on combustion duration were also considered. The calculated results of the intake manifold pressure, heat release rate, and cylinder pressure were compared with the experimental data. The results of this study show that this modeling process approximates reality.

Since recently exhaust gas regulation for a non-road small engine as well as commercial vehicle engine has been enforced, a carburettor of a small engine should be replaced by an electronic fuel injection system. In this study, the spray characteristics of the 400cc gasoline small engine injector has been experimentally analyzed. Based on the experimental results, suitable injector for the small engine has been selected. Through the test rig measuring spray mass distribution, fuel distribution characteristics of 3 hole- and 6 hole-injector has been analyzed. Through the visualization equipment, injector spray angle, penetration length and spray width have been measured and analyzed. Considering spray characteristics and stability, 6 hole-injector is selected for the 400cc gasoline small engine.

Small, handheld two-stroke engines used for lawn and garden work (e.g., string trimmers, leaf blowers, etc.) can emit a variety of potentially toxic carbonaceous air pollutants. Yet, the emissions effluents from these machines go largely uncharacterized, constraining the proper development of human exposure estimates, emissions inventories, and climate and air quality models. This study samples and evaluates chemical pollutant emissions from the dynamometer testing of six small, handheld spark-ignition engines—model years 1998–2002. Four oil–gas blends were tested in each engine in duplicate. Emissions of carbon dioxide, carbon monoxide, and gas-phase hydrocarbons were predominant, and the PM emitted was organic matter primarily. An ANOVA model determined that engine type and control tier contributed significantly to emissions variations across all identified compound classes; whereas fuel blend was an insignificant variable accounting for

There is still significant improvement that can be made in terms of improving the fuel efficiency of modern internal combustion engines. Often times this decrease in fuel efficieny is a result of an incomplete combustion reaction. Incomplete combustion reactions may result from two main aspects during the combustion process: (1) incomplete vaporization of fuel before ignition, and (2) insuffient oxygen in the combustion environment. The work here aims to develop a novel system that maximizes fuel efficiency, while minimizing the effects of incomplete combustion. This was accomplished by incorporating ultrasonic vaporization techniques, inconjunction with an oxygen concentrator, into a small engine. The engine performance was compared between the conventional and enhanced systems.

A project dealing with small gas turbine engine inlet total pressure distortion testing was solved at the University of Defence. Within this project a new device for creation and measurement of the total pressure inlet distortion was designed. In the early stage of the project there was a need of significant amount of testing for evaluation of newly designed device, foundation of measurement methodology, testing of basic distortion screen designs and their affects. In order to save expanses for the jet engine operation for these initial tests it was replaced by a model device drawing air through the engine inlet. This paper describes design of the measurement device, its initial tests and lessons learned from this development. Difficulties encountered with substitution of the jet engine by standalone compressor are also presented.

After the great success of the application of the common rail system on the vehicles, it became very attractive to apply this new injection system on small engine, which has much industrial application. This work represents a comprehensive study on optimising the magnetic properties of the electro-injector used in off-road application. In this work analytical studies were implemented to simulate the solenoid actuator for the electro-injector, depend on the required quantities of the diesel oil. To reach our goal different models with different concepts were built-up to evaluate the best magnetic properties of the applied materials. Different types of steels were simulated, to achieve the better working force from the solenoid actuator. Different models were built-up by varying the material properties from one side and the working parameters such as the coil turn, current for a fixed gap between the armature and the back iron from the other side. Comprehensive structural modelling was carried out to secure and optimise the function ability of the electro-injector, in particular the interference fitting between different parts of this injector. The analytical study was carried out with the application of FEM using ANSYS 6.1 and Pro/Mech. programmes. As a result of this simulation, the magnetic characterization has been determined, by choosing the right steel for the best solenoid actuator application. The electro-injector parts were optimised. Finally, the experimental and analytical results both were in good agreement.

Conceptual design studies have been conducted for a propulsion system on an advanced transport aircraft, with the objective to define an engine/aircraft configuration that would be able to meet the NASA N+3 goal for fuel burn reduction at entry into service in 2035. The vehicle configuration is the MIT D8.6 airplane, which has two boundary layer ingesting engines located at the upper aft fuselage. The engine design space is high overall pressure ratio and high bypass ratio at relatively small thrust size and very small core engine physical size. Conventional turbofan engine architecture encounters significant challenges in high-OPR small engine design space associated with accommodation of a concentric fan drive shaft through the very small core and adverse effect of small core size on component efficiency. Conceptual design of an alternative engine architecture is defined based on a two-spool gas generator core that is mechanically uncoupled from the propulsor such that the fan drive shaft does not pass through the core.

This paper investigates abnormal combustion during the cranking phase of spark-ignition small engines, specifically the occurrence of backfire at the release of the starter motor during kickback. The research focusses on the influence of fuel composition, mainly in terms of ethanol percentage, on backfire occurrence. Interest in this abnormal combustion is growing due to the increased use of fuels with different chemicalphysical properties with respect to gasoline. Moreover, this issue will become even more topical due to the implementation of simple control and fuel supply systems on low cost-engines, which are widely used in developing countries. Experimentation was carried out in an optically accessible engine derived from a 4-stroke spark ignition engine for two-wheel vehicles. The test bench was instrumented and adapted in order to simulate the engine conditions that lead to anomalous ignition in the intake duct (backfire) during the reverse rotation of the engine (kickback). Two different test procedures were developed with the aim of promoting the ignition at the intake. Major engine parameters were measured, such as the incylinder pressure, the pressure at the exhaust and at the intake; in order to characterize the engine conditions and to monitor the ignition in the intake manifold. Furthermore, an optical investigation of the combustion chamber was performed using high spatial and temporal resolution measurements. Engine and optical data were correlated and the analysis allowed characterization of backfire during kick-back, enabling identification of the conditions that make backfire more probable and to observe the influence of fuel composition

The simulation of a jet engine behavior is widely used in many different aspects of the engine development and maintenance. Achieving high quality jet engine control systems requires the iterative use of these simulations to virtually test the performance of the engine avoiding any possible damage on the real engine. Jet engine simulations involve the use of mathematical models which are complex and may not always be available. This paper introduces an approach based on Genetic Programming (GP) to model different parameters of a small engine for control design such as the Exhaust Gas Temperature (EGT). The GP approach has no knowledge of the characteristics of the engine. Instead, the model is found by the evolution of models based on past measurements of parameters such as the pump voltage. Once the model is obtained, it is used to predict the behaviour of the jet engine one step ahead. The proposed approach is successfully applied for the simulation of a Behotec j66 jet engine and the results are presented.

Benchmarks are defined, against which the performance of a given engine may be judged, with general indications for engine selection and aspects of design through which improvements may be sought. These are derived from published compilations of engine performance data obtained from suppliers around the world, which, if regularly refined and updated, will allow progress in small engine design to be systematically monitored and encouraged.

The new DK series engines are developed as the next generation of engines, with 5 common concepts: environmental protection, high output with smaller engine size, high efficiency, reduction in maintenance and running cost, and increase in reliability and durability.Other than the in-line 6 and 8 cylinder types, the DK-20 model comes with 3 and 5 cylinders, and the DK 26 model with a 5 cylinder type. Development of various cylinder number types within the same model allows the new DK series to cover a wide range of output with a small engine model lineup.With the development of 3DK-20, the low output range that had been covered by high revolution engine running on marine diesel oil can now be covered by engine running on heavy diesel oil. Also, when looking at parts around the piston area, a 3 cylinder engine effectively halves the parts number compared to 6 cylinder engines with the same output. This achieves great reduction inrunning cost and maintenance costs.The follwing will introduce the new DK series engines, with details on design, performance, and benefits.

The research program described in this report is part of the AFRL Capstone efforts for undergraduate engineering students and is focused on studying the impact of using a plasma discharge system to enhance the combustion process in a small-scale internal combustion engine. The effects of two plasma systems were demonstrated using a small-scale engine (.1-100kW/USAF Unmanned Aerial Systems (UAS) Groups 1-3). The project was integrated into the Capstone undergraduate design program at Michigan State University as well as providing part support for graduate level research. In total, the project included the participation of eight undergraduate mechanical engineering students and the final research was exhibited by several of the students at the University Capstone Project Demonstration Day in the Small Engine Research Laboratory (SERL) at Wright Patterson Air Force Base in June, 2012.

Alkylate is an environmentally advantageous petroleum refinery fraction presently available in large volumes. Today, almost all alkylate produced is mixed into petrol for automobiles. This study concludes that it is better to use unmixed alkylate as fuel for small engines, especially two-stroke engines. The main reason is that hydrocarbon emissions from the same quantity of fuel are more than one order of magnitude larger from these engines than from car engines. Alkylate for small engines has been used in Sweden for several years, and is well established within forestry. Its use in parks, public places, cemetaries, etc. is rapidly increasing. From a production point of view, prompt introduction of alkylate petrol for most small engines appears to be possible in both Western Europe and the US, without dramatically affecting the pool of petrol for automobiles.

Accurate, repeatable measurement of tailpipe emissions is an important factor in the development of internal combustion engines and testing of alternative fuels. A dilution tunnel simulates the action of exhaust mixing with atmospheric gases and prevents condensation prior to gas and particulate measurements. In this work, a micro dilution tunnel was designed for the University of Idaho Small Engine Laboratory (SEL), and experiments were conducted to establish the controllability and accuracy of the tunnel. The tunnel design implements partial flow, Constant Volume Sampling (CVS) using an ejector diluter. Real-time measurement of CO2, CO, O2, NOx, hydrocarbons, and particulate emissions are collected using the combination of a NDIR/electrochemical 5-gas analyzer and a Tapered Element Oscillating Microbalance (TEOM). Data from these instruments and the flow conditioning equipment are collected and logged by a National Instruments data acquisition system. For the desired 11:1 dilution ratio, the system should be operated at 700°F suction temperature and 35 psia motive pressure. This results in an uncertainty of 3% at the 80% confidence level. A procedure has been developed for obtaining and verifying dilution ratios between 11:1 and 15:1. The characterization and use of an ejector diluter have made it possible to create an inexpensive dilution tunnel that will be useful in studying effects of freezing chemical reactions, and analyzing emissions of diesel and two-stroke engines that typically produce elevated levels of hydrocarbons and particulates beyond the saturation range of many emissions analyzers.Copyright © 2011 by ASME