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Stricter requirements for power in engines and difficulties in fueling gasoline engines at the airport make aircraft engine manufac-turers design new engines capable of combusting fuel derived from JET-A1. New materials used in compression-ignition engines enable weight reduction, whereas the technologies of a Common Rail system, supercharging and 2-stroke working cycle enable us to increasethe power generated by an engine of a given displacement. The paper discusses the parameters of about 40 types of aircraft compression ignition engines. The parameters of these engines are compared to the spark-ignition Rotax 912 and the turboprop. The paper also shows trends in developing aircraft compression-ignition engines.

Introduction Recently, employment of rotary tillers has been expanded in gardens and small farms, especially in the northern of Iran. However using the L-shaped blades in the conventional rotary tillers have some problems such as severe vibration problems, weeds stucking around the blades, forming the plow pan and lower performance due to the less powers of such small rototillers. Therefore in order to overcome the above mentioned problems, a rototiller with new ridged blades was designed, fabricated and tested in this research. Materials and Methods Experiments were carried out in one of the citrus orchards in Mazandaran, Sari. The experimental design was split plots based on randomized complete block design with three replications. The soil moisture as main plot varied in two levels of 13.5-21.9 and 21.9-30.3 percent based on dry weight and the rotational speed of blades as subplots varied in three levels of 140-170, 170-200 and 200-230 rpm. The measured parameters consist of soil particle mean weight diameter, soil bulk density, soil crumbling percentage, specific fuel consumption and machine efficiency. The diameter of soil particles was measured using a set of standard sieves with diameter ranging from 0.5 to 8 mm. Then a laboratory shaker was used to sift the samples. Each sample was shaken in 30 sec. The fuel consumption during the experiments was determined by the filled fuel tank method. Analysis of variance (ANOVA) and mean comparisons and interaction between the parameters were performed using the SPSS 16 software. Results and Discussion The results indicated that the soil particle mean weight diameter reduced by increasing blades rotational speed in both examined soil moisture contents. Results indicated that the soil crumbling percent increases with increasing the rotational speed. The main reason for this effect could be due to the more energy transferring to the soil at higher rotational speeds, which result in further crumbling of the soil slices. Regarding the results obtained in this study, the specific fuel consumption increased at first in a light slope, then in a steep rise with increasing the blades rotational speed. The reason can be the higher crumbling percent of the soil at higher rotational speeds and higher soil moisture contents (at the range of 21.9-30.3%), providing the more specific energy consumptions. The specific fuel consumption was the maximum at higher soil moisture content of 30 %. The results indicated that the blades rotational speed and soil moisture content had no significant effect on the field efficiency of the examined rototiller. The field efficiency varied in the range of 92 to 97% in all of the experiments, i.e., rotational speed between 140 to 230 rpm and moisture content ranging from 13.5 to 30.3%. The reason for that was due to the roughly similar turning times, minor adjustments, changing operators and some other parameters influencing the field efficiency. Reduction of the rotational speed of the rototiller from high-to-moderate speeds leads to decrease the fuel consumption to 17 liter ha-1, which could be significant in wide scale of soil tillage operations. As a general result, reduction of the rotational speed had some considerable advantages such as reducing power requirements, reducing blade wearing and maintaining soil structure. Conclusions Influence of soil moisture and rotational speed of blades on the soil particle mean weight diameter, soil crumbling percentage and specific fuel consumption were significant (P

This paper presents an analysis of the gas turbine real process (with all losses included) before and after a major maintenance. The analysis of both gas turbine operating regimes is based on data measured during its exploitation. Contrary to authors’ expectations, the major maintenance process did not result either in any decrease in losses or increase in efficiencies for the majority of the gas turbine components. However, the major maintenance influenced positively the gas turbine combustion chambers (reduction in losses and increase in the combustion chambers efficiency). After the major maintenance, the overall process efficiency decreased from 43.796% to 41.319% due to a significant decrease in the air mass flow rate and to an increase in the fuel mass flow rate in combustion chambers. A decrease in the gas turbine produced cumulative and useful power after a major maintenance also increased the specific fuel consumption. [ABSTRACT FROM AUTHOR]

India produces 500 million metric tones of renewable agricultural biomass every year, primarily used as a cooking fuel. Inefficient combustion of biomass is one of the major hindrances for the effective utilization of this vast reserve of energy. Inefficient combustion may occur due to several factors such as lack of proper air circulation, improper packing of fuel and excess moisture content in the fuel. This paper describes the performance evaluation of three improved stoves; natural draft TLUD stove and forced draft Purti and Mpurti stove using three kinds of biomass fuel as wood chips, wood pellets and coconut shell. It was found that the thermal efficiency of the natural draft TLUD stove was 26–27%, electric fan operated Purti stove was 44–45%, and solar fan operated Mpurti stove was 46–48%. This performance was assessed by the standard laboratory-based water boiling test method (WBT) to get thermal efficiency, burning rate, boiling point, specific fuel consumption and firepower. The economic analysis study was carried out to get an idea about the approximate cost that would be incurred per month on the fuel. All these desirable parameters are maximized for the efficient combustion of fuel. The gaseous components like CO and CO2 obtained over the fuel bed are analyzed using gas chromatography. Particulate matter (PM2.5) was measured by the fine particulate sampler. PM2.5 concentration for traditional cookstoves was much higher than studied forced draft Mpurti (510 ± 45 μg/m3) and Purti stove (677 ± 40 μg/m3). The reduction in the indoor concentration of PM2.5 for Mpurti is about 60–63% as compared to traditional stove. Mean CO emissions on a volumetric basis during the cold start and hot start phase were lowest for Mpurti forced draft stove (2.41%). The study reveals that clean cooking can be achieved using the forced draft Mpurti stove. [ABSTRACT FROM AUTHOR]

There are many ways and methods to reduce exhaust gases emissions on modern ships. One of the most effective ways to reduce NOx and SOx emissions is to use of exhaust gas recirculation (EGR technology). The EGR system disadvantage is an increase in back pressure through additional pressure losses in the scrubber and heat exchanger, which entails an engine fuel efficiency deterioration. Creating a reliable and efficient heat exchanger for cooling recirculation gases is a complex task due to deposits and pollution emitted by these gases. In the present work, the jet apparatus effectiveness named aerothermopressor is analyzed in the scheme with exhaust gases recirculation of the ship low-speed two-stroke engine. Aerothermopressor is a two-phase jet for contact disperse cooling, in which by increasing the heat from the gas stream the gas pressure and cooling are increased. The calculation of the characteristics of the engine was carried out, both in nominal, and in operating modes and in all possible range of partial loads. The installation of the aerothermopressor before the scrubber is proposed, which allows reducing engine thermal load. Increasing the pressure in the aerothermopressor by 0.2-0.4 ∙ 105 Pa (6- 12%) allows reducing the back pressure in the gas exhaust system and thus reducing the load on the exhaust gas recirculation fan and when the engine load is higher than 75% in the cold zone, the fan is not needed, which additionally allows to reduce the specific fuel consumption. The parameters of the exhaust gases that are going to be recirculated and the processes of their gas-dynamic cooling in the aerothermopressor are based on the developed technique and program using the thermodynamic and gas dynamics equations. The proposed scheme-design solution allows at a high environmental friendliness of the existing exhaust gas recirculation system to provide a certain reduction in specific fuel consumption. It was determined that the engine specific fuel consumption has been decreasing when the aerothermopressor is used to Δge = 2.5-3.0 g/(kW∙h) (1.5-1.7%). [ABSTRACT FROM AUTHOR]

Microbial-derived biodiesel was tested on a lab scale CI diesel engine for carrying out exhaust emission and performance characteristics. The performance, emission, and combustion characteristics of a single cylinder four stroke fixed compression ratio engine when fueled with microbial bio-diesel and its 10–30% blends with diesel (on a volume basis) were investigated and compared with conventional diesel. The bio-diesel was obtained from microbes which were grown by combining distillery spent wash with lignocellulosic hydrolysate at nutrient deprived conditions. The microbes consumed the wastes and converted the high strength waste water into lipids, which were trans-esterified to form bio-diesel. Testing of microbial bio-diesel blends with ordinary diesel at different loading pressures and the emission characteristics were compared. Results indicate that with increasing of the blends, reduction of HC and CO emissions were observed, whilst brake thermal efficiency maxed out at 20% blending. Further increase of blends showed a tendency of increasing of both emissions in the exhaust stream. The Brake Specific Fuel consumption was observed to decline with blending until 20% and then increased. The nitrogen oxide emissions, however, were found to increase with increasing blend ratios and reached a maximum at 20% blend. The escalation of HC, CO, CO2, and NOx emissions was also observed at higher blending ratios and higher engine loads. The performance studies were able to show that out of the three blends of biodiesel, 20% biodiesel blend was able to deliver the best of reduced hydrocarbon and carbon monoxide emissions, whilst also delivering the highest Brake thermal efficiency and the lowest Brake Specific Fuel consumption. [ABSTRACT FROM AUTHOR]

More than half the kitchens in the world use traditional wood burning stoves for cooking. The traditional stove involves burning of wood in open which leads to inefficient combustion with 5 to 10% thermal efficiency. In this study, highly improved stoves were designed and developed by varying height, shape and air supply. It was observed that the cylinder shaped stoves performed with higher thermal efficiency than the frustum stoves. The height of the combustion chamber was optimized at 12 cm with better combustion (19.83%) and higher heat transfer rate (20.15%). The primary air supply of 80% and secondary air of 20% resulted in higher combustion temperature (660.9 °C) and lesser air pollutants of 0.82 g L-1 (CO) and 142 g L-1 (HC). The cylindrical combustion chamber of height 12 cm with primary sir supply and secondary air supply of 80 and 20%, respectively resulted to higher thermal efficiency of 22.86%, specific fuel consumption of 0.59 kg L-1 and heat transfer efficiency of 23.08%. [ABSTRACT FROM AUTHOR]

Using vegetable oils as fuel for diesel engines in the long term may cause some extremely serious problems, such as an increase in toxic emission and pollutants, reduction in engine power, and degradation of lubricating oil (LO) due to deposit formation, abrasion, and wear, as well as damaged engines. In this study, the 4 stroke-4 cylinder-Yanmar TF120M diesel engine was tested the endurance during 300 h on diesel fuel (DF) and preheated straight jatropha oil to evaluate the effects of these two fuel types on the degree of deposit formation, LO, brake-specific fuel consumption (BSFC), and emission characteristics. The results showed that, although the properties of straight jatropha oil were improved by preheating at 90°C (SJO90), the degree of deposit formation for SJO90 was observed higher in comparison with DF. Furthermore, scanning electron microscopy (SEM) was used to analyze the deposits. Related to engine performance and emission characteristics, higher BSFC, unburnt hydrocarbons and carbon monoxide emissions, and lower nitrogen oxide emissions for SJO90 compared to DF were presented. About the results of LO analysis, the excessive metal concentrations in LO of test engine for SJO90 were much higher than the case of using DF. Besides, an increase in LO density and a reduction in LO viscosity also showed the degradation of LO for SJO90 in comparison with DF after test time. [ABSTRACT FROM AUTHOR]

Highlights • It is presented a model for determining specific fuel consumption of diesel engine. • Polynomial for calculating the minimum specific fuel consumption points is formed. • Engine economic operation curve model is given. • The effects of engine operating at economical operation curve are analyzed. Abstract An approach to determine the diesel engine minimum specific fuel consumption for a given engine power, and economic operation curve model is presented. The approach is based on experimentally obtained data on the specific fuel consumption and engine power. The specific fuel consumption experimental data obtained by engine manufacturer are approximated by a third order polynomial fit which is a function of an engine effective pressure and number of revolutions. The minimum specific fuel consumption is defined by the contact points of the constant specific fuel consumption curves and the curves of constant engine power. Based on the coordinates of the points, analytically obtained for given power values, engine economic operation curve model is defined. Economic operation curve enables a significant simplification of operation regime regulation according to the criteria of the highest economy. The method is demonstrated using the experimental data of the IMR S44/V diesel engine. [ABSTRACT FROM AUTHOR]

One of the promising ways in environmentalizing marine internal combustion engines is the neutralization of harmful substances in exhaust gases through particular gas recirculation (EGR-technology). However, the use of such techniques conflicts with the engine's energy efficiency. In the work presented, the scheme-design solution of the exhaust gas recirculation system with using the heat of recirculation gases by an ejector refrigeration machine for cooling the air at the intake of ship's main engine is proposed. The effect of using the heat of recirculation gases for cooling the air at the intake of the engine is analyzed taking into account the changing climatic conditions for a particular vessel's route line. It is shown that the use of an ejector refrigeration machine reduces the air temperature at the entrance of the main engine by 5-15 ° С, which reduces the specific fuel consumption by 0.5-1.5 g/(kW∙h). This reduces emissions of harmful substances when the engine is running with recirculation of gases, in particular, NOx by 30-35%; SOx by 10-12%. [ABSTRACT FROM AUTHOR]

In this study, the effects of reference fuels with different research octane numbers (RON0, RON20 and RON40) on engine performance were investigated at 40 °C intake air temperature and full load in a four cylinders HCCI engine. The operating range for the HCCI engine has been determined and the brake specific fuel consumption maps for each fuel have been created. Combustion characteristics were investigated at a constant engine speed of 1000 rpm. The heat release rate and in-cylinder pressure lambda values of λ=2.15 were obtained for the engine operating in natural-aspirated mode. As the number of octane increases, the engine load increases but the operating range decreases. The lowest BSFC values were obtained at 238.7 g/kWh for RON0, 251.3 g/kWh for RON20 and 276.6 g/kWh for RON40. It was observed that there was a delay in the start of combustion as the number of octane increased. The best CA50 value was obtained 6 °CA from aTDC with RON40 because of the slower burning than RON0 and RON20. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Energy factors were obtained for gasoline and ethanol fueled engines and vehicles. • Use of 3D engine BFSC maps produced consistent results for flexible fuel engines. • Energy conversion factor for E22 was 0.43 L/kW h, from laboratory and road tests. • Energy conversion factor for E100 was 0.62 L/kW h, from laboratory and road tests. Abstract This work investigates the energy factors for fuel conversion from the analysis of brake specific fuel consumption (BSFC) maps of a sample of 15 engines, representative of 75% of current models available in the Brazilian market. The method also employs the engine driving patterns of power output versus crankshaft speed obtained from bench dynamometer tests. The energy factors obtained from the engine analysis was validated against experiments carried out with two production vehicles in laboratory tests following the 1975 US Federal Test Procedure (FTP-75) procedure and road tests following 16 different urban and highway routes. The fuels used in the tests were hydrous ethanol (E100, 6 v/v % water) and a blend of 22 v/v % anhydrous ethanol and 78 v/v % gasoline (E22). The energy factors found from the 3D engine BSFC map analysis were higher than those obtained from the Willans line, currently adopted as a standard, by 52% for E22 and 57% for E100. The results from the 3D engine BFSC maps and the first vehicle following the FTP-75 cycle and 15 road routes were similar, also close to the results from the second vehicle, qualifying them to be representative of modern flexible fuel spark ignition engines and vehicles. [ABSTRACT FROM AUTHOR]

Finite element model (FEM)-based simulations are conducted for the application of a thermoelectric generator (TEG) between the hot core stream and the cool bypass flow at the nozzle of an aviation turbofan engine. This work reports the resulting requirements on the TEG design with respect to applied thermoelectric (TE) element lengths and filling factors (F) of the TE modules in order to achieve a positive effect on the specific fuel consumption. Assuming a virtual optimized TE material and varying the convective heat transfer coefficients (HTC) between the nozzle surfaces and the gas flows, this work reports the achievable power output. System-level requirement on the gravimetric power density (>100 Wkg−1) can only be met for F ≤ 21%. When extrapolating TEG coverage to the full nozzle surface, the power output reaches 1.65 kW per engine. The assessment of further potential for power generation is demonstrated by a parametric study on F, convective HTC, and materials performance. This study confirms a feasible design range for TEG installation on the aircraft nozzle with a positive impact on the fuel consumption. This application translates into a reduction of operational costs, allowing for an economically efficient TEG-installation with respect to the cost-specific power output of modern thermoelectric materials. [ABSTRACT FROM AUTHOR]

Fuel catalytic additives have been tested for many years. Herein, their influence on the overall efficiency of combustion engines is investigated, and their pro-ecological impact is assessed. The majority of this research concerns diesel engines. Despite many advantages, to this day, the use of catalytic additives has not become widespread. Wishing to clarify the situation, a research group from the Wroclaw University of Science and Technology decided to investigate this matter, starting with verification tests. This article presents the methodology and results of testing an actual diesel engine, and evaluates the effects of the use of a fuel catalytic additive. The focus was on the analysis of fuel consumption and exhaust gas emissions from a Doosan MD196TI engine. The tested additive was a commercial fuel performance catalyst (FAMAX) with up to 5% ferric chloride as an organometallic compound. The proportion of the mixture with the fuel was 1:2000. These studies provide an energy and ecological assessment of propulsion in inland vehicles relative to current exhaust emission standards. The tests were carried out in accordance with the ISO 8178 standard, albeit on a much broader scale regarding engine operation than required by the standard. In this way, a set of previously published data was more than doubled in scope. Detailed conclusions indicate the positive effect of the tested fuel additive. The emission values decreased, on average by 16.7% for particulate matter (PM), 10.1% for carbon monoxide (CO), and 7.9% for total hydrocarbons (THC). Unfortunately, the amount of nitrogen oxides (NOx) increased by 1.2%. The average difference in specific fuel consumption (BSFC) between the fuel with additive and pure diesel fuel was 0.5%, i.e. below the level of measurement error. The authors formulated the following scientific relationship between the thermal efficiency of the engine and the operation of the catalyst: the effect of the catalyst on the combustion process decreases with the increase of the thermodynamic efficiency of the engine. This conclusion indicates that despite the proven positive effect of catalysts on the combustion process, they can only be used in markets where engines with low thermal efficiency are used, i.e., older generation engines.

The first stage of implementation of the "Energy Strategy up to 2030" is finished in 2015. Estimated implementation of the indicator parameters of the first stage (2008-2015g): power consumption, power generation, power inputs, power structure, specific fuel consumption for electricity and heat, the need for fuel. For a number of indicators of the Energy Strategy are not achieved even limits, for some indicators deviations is minimal. In general, the phase assignment is not fulfilled, and it is obvious that the following steps should be adjusted downwards.

The brief presents some principles of the ON/OFF operational strategy applied to energy management of a hybrid internal combustion engine (ICE) based auxiliary power unit (APU). It is shown that significant reduction of fuel consumption (78% for the example system presented) and maintenance expenses (80% operation time decrease was attained by the system) may be achieved by such a strategy, shifting the system operation point towards corresponding optimal region. The side effect of aggravated amount of starting events is cured by employing an actively balanced supercapacitor (SC)-based emergency starter (SCS). The SCS operates as short-time energy storage device, charging from the battery at a low rate and then providing a current burst required for proper internal combustion engine starting. Current sensorless method of automatic connection (based on bus voltage sensing) and disconnection (based on sensing the voltage across bidirectional MOSFET-based switch) of the SCS is also proposed. The proposed circuitry, successfully validated by experiments, may be arbitrarily scaled up or down according to application rating.

Introduction: Today, all kinds of vehicle engines work with fossil fuels. The limited fossil fuel resources and the negative effects of their consumption on the environment have led researchers to focus on clean, renewable and sustainable energy systems. In all of the fuels being considered as an alternativefor gasoline, methanol is one of the more promising ones and it has experienced major research and development. Methanol can be obtained from many sources, both fossil and renewable; these include coal, natural gas, food industry and municipal waste, wood and agricultural waste. In this study, the effect of using methanol–unleaded gasoline blends on engine performance characteristics has been experimentally investigated. The main objective of the study was to determine engine performance parameters using unleaded gasoline and methanol-unleaded gasoline blends at various engine speeds and loads, and finally achieving an optimal blend of unleaded gasoline and methanol. Materials and Methods: The experimental apparatus consists of an engine test bed with a hydraulic dynamometer which is coupled with a four cylinder, four-stroke, spark ignition engine that is equipped with the carbureted fuel system. The engine has a cylinder bore of 81.5 mm, a stroke of 82.5 mm, and a compression ratio of 7.5:1 with maximum power output of 41.8 kW. The engine speed was monitored continuously by a tachometer, and the engine torque was measured with a hydraulic dynamometer. Fuel consumption was measured by using a calibrated burette (50cc) and a stopwatch with an accuracy of 0.01s. In all tests, the cooling water temperature was kept at 82±3˚C. The test room temperature was kept at 29±3˚C during performing the tests. The experiments were performed with three replications. The factors in the experiments were four methanol- unleaded gasoline blends (M0, M10, M20 and M30) and six engine speeds (2000, 2500. 3000, 3500, 4000 and 4500 rpm). Methanol with a purity of 99.9% was used in the blends. All experiments were performed at 50% open throttle. Engine performance characteristics for fuel blends were compared with unleaded gasoline. Results and Discussion: The experimental results showed that adding methanol to unleaded gasoline increased brake torque and brake power in the M10 and decreased in the M30 compared to merely usingpure gasoline. Engine behavior when using M20 blend was similar to that of using pure gasoline (M0). The brake power and torque at engine speeds 2500, 3000, 3500 and 4000 rpm for M10 were increased by 5.42%, 7.76%, 14.89% and 16.78% compared to when these parameter relate to pure gasoline (M0), respectively, whereas the brake power and brake torque for M30 blend at engine speeds 2000, 2500, 3000, 3500, 4000 and 4500 rpm compared to when using pure gasoline was decreased by 6.91%, 8.1%, 6.23%, 5.29%, 4.59% and 14.27%, respectively. The experimental results showed that brake specific fuel consumption for M30 blend was increased at all engine speeds. The increase in specific fuel consumption values for this blend from 2000 - 4500 rpm were 17.78%, 16.38%, 13.06%, 10.99%, 14% and 19.11%, respectively. Also, the specific fuel consumption for the M20 was similar to the specific fuel consumption of pure gasoline. Comparing the brake specific fuel consumption of M10 to M0 fuel at 2500, 3000, 3500, 4000 and 4500 rpm this parameter was decreased by 1.9%, 6.03%, 8.91%, 13.85% and 5.55%, respectively. As the methanol content in the fuel blends increases, brake thermal efficiency also increases at all engine speeds and in all used fuels blends. The thermal efficiency at 2000, 2500, 3000, 3500, 4000 and 4500 rpm using M10 was increased by 3.73%, 8.12%, 12.43%, 15.57%, 22.34% and 12.01%, respectively in comparison to pure gasoline. These values for M20 were 4.14%, 7.82%, 10.12%, 13.37%, 18.94% and 13%, and for M30 were 2.69%, 3.89%, 6.35%, 8.01%, 5.12% and 0.78%. Conclusions: From the results of the study, the following conclusions can be deduced: 1- Using methanol as a fuel additive to unleaded gasoline causes an improvement in engine performance. 2- The largest increment in engine torque and brake power compared with M0 showed about 16.78% with M10 at 4000 rpm. 3- Minimum brake specific fuel consumption was obtained at 4000rpm with M10 fuel. 4- Thermal efficiency increased compared to the pure gasoline usage at all engine speeds and in all used fuel blends. The largest increment in brake thermal efficiency compared with M0 showed 22.34% with M20 at 4000 rpm. 5- The 10 vol. % methanol in fuel blend gave the best results for all measured parameters at all engine speeds.

About 60% of the mechanical energy consumed in mechanized agriculture is used for tillage operations and seedbed preparation. On the other hand, unsuitable tillage system resulted in soil degradation, affecting soil physical properties and destroying soil structure. The objective of this research was to compare the effects of three types of secondary tillage machines on soil physical properties and their field performances. An experiment was conducted in a wheat farm in Jouybar area of Mazandaran as split plots based on randomized complete block design with three replications. The main independent variable (plot) was soil moisture with three levels (23.6-25, 22.2-23.6 and 20.8-22.2 percent based on dry weight) and the subplot was three types of machine (two-disk perpendicular passing harrow, Power harrow and Rotary tiller). The measured parameters included: clod mean weight diameter, soil bulk density, specific fuel consumption, machine efficiency and machine capacity. The effects of treatments and their interactions on the specific fuel consumption, machine efficiency and machine capacity and also the effects of treatments on bulk density were significant (P