Friction Mean Effective Pressure Research Articles

Engine performance characteristics using microalgae derived dioctyl phthalate biofuel during cold, preheated and hot engine operation

This study presents a comprehensive analysis of the engine performance parameters during different temperature-based operating conditions: cold, preheated and hot. Novel blends of Di-octyl Phthalate (DOP) and diesel were prepared by using 10 and 20% DOP (%v/v), named B10 and B20, respectively, and compared with ultra-low sulphur diesel (B00). The experiments were conducted on a heavy-duty diesel engine using a custom-designed cold-to-intermediate temperature drive cycle emulating frequent engine stop/start at loads of 100, 50, 75 and 25%, at a constant speed of 1500 rpm. The maximum torque produced by the engine at wide open throttle (WOT), under fully warmed up operation, was within ± 1%, using all fuels. During ambient operation, the improvements in indicated thermal efficiency (ITE) showed dependence on better fuel mixing rather than engine load and improved by 5% and 1% using B20 and B10, respectively, when the engine run progressed from 100% to 25% load. During ambient operation, the indicated mean effective pressure (IMEP) and the brake mean effective pressure (BMEP) were lower by 2 and 4% using B10, and 4 and 7% using B20, when compared to B00, respectively. When the engine was fully warmed-up, the friction mean effective pressure (FMEP) showed an increase of 40 – 80% using the blended fuels, compared to B00 fuel. During ambient operation, the blowby was 10% and 7% lower using B20 and B10 blended fuels, respectively, compared to B00 fuel. During ambient operation, the brake specific fuel consumption (BSFC) was higher by 4 and 10% using B10 and B20 blended biofuels, respectively, compared to B00. Engine parameters such as MEP and SFC were found to deteriorate proportionally with increased oxygen (O2) content in the biofuel blends.

Influence of thermal effect in piston skirt lubrication considering thermal deformation of piston and cylinder liner

With the development of high-strength marine diesel engines, piston skirt lubrication plays an increasingly important role. In this study, to ensure that the mixed lubrication can be applied, the contact of the PS corner and CL is simplified to a spring–damper system. A coupled dynamical–tribological numerical model of a piston skirt is proposed by combining mixed lubrication and the secondary motion of the piston. The model is then used to study how the thermal effect of the piston skirt-cylinder liner friction pair affects (i) the secondary motion of the piston, (ii) the contact force of the piston-skirt corner points, and (iii) the lubrication characteristics, while considering ring friction, friction moment of piston pin and three-dimensional thermal deformation of the piston and cylinder liner. The results show that the secondary motion under the thermal condition is less than that under the cold condition, and the reverse rotation of the piston under the thermal condition occurs earlier. Asperity contact and corner points contact appear under the thermal condition, and the friction mean effective pressure under the cold condition is 47.7% greater than that under the thermal condition. Overall, it is necessary to consider the thermal effect of the piston skirt-cylinder liner friction pair.

Fretting behavior of piston ring-cylinder liner components of a diesel engine running on TiO2 nanolubricant

This experimental research presents the friction and wear characteristics of piston ring-cylinder liner component of a diesel engine running on commercial engine oil (5W-30) and TiO2 nanoparticle (~20 nm, ≥99.5% trace metals basis) incorporated 5W-30 engine oil (nanolubricant) to observe the performance parameters in terms of mean effective pressures and smoke emissions. Dynamic light scattering was utilized to examine the nanoparticle dispersion in the lubricant. Thermo-gravimetric analysis on nanoparticles was conducted to examine the thermal endurance during abrasion tests. The samples directly cut from the spare piston ring of the test engine underwent severe friction and wear tests via linear friction module. Coefficient of friction was considered as comparison param-eter to understand the tribological behavior of friction pairs submerged in two different lubricants. Scanning electron microscopy analysis was conducted to observe morphology of the nanoparticle and to analyze the surface structure of the samples before and after the abrasion tests. Atomic force microscopy analysis was done to obtain the 3D images of the worn surfaces and to make a comprehensive comparison of tribological performance between engine lubricant and nanolubricant. The results depicted that, TiO2 is effective in reducing coefficient of friction by an average of 10.37% and wear rate by 33.58% as well as improving brake mean effective pressure by an average of 4.95% and reducing friction mean effective pressure by an average of 9.34% when compared to those of the engine oil. In parallel with reduced friction, TiO2 incorporation in engine oil yielded an average reduction of 9.11% in smoke opacity. The experiments suggest promising results in terms of utilization of low friction, fuel efficient and environmental friendly internal combustion engines fulfilling strict emission regulations.

Exergy and energy analysis during cold-start and warm-up engine operation

Cold-start is an inevitable part of the daily driving operation for most vehicles. Given that exergy analysis can evaluate the sources of losses qualitatively and quantitatively using the first and second laws of thermodynamics, this study investigated the impact of engine temperature on energy and exergy parameters during engine warm-up. Using a turbocharged Cummins engine, the performance and emissions data were measured, and energy and exergy parameters were formulated from the experimental data. Engine warm-up period was divided into seven phases, including official hot-start and cold-start, and some phases which are not considered as cold-start or hot-start by regulations. This study evaluated different parameters related to energy analysis (brake power, friction mean effective pressure [FMEP], brake specific fuel consumption [BSFC] and brake thermal efficiency [BTE]), exergy analysis (fuel input exergy, exhaust heat loss, exergy destruction and exergetic efficiency) and their correlations. Results showed that as the engine warmed up, the fuel exergy, exhaust heat losses, and exergy destruction decreased by 2.3, 34.1 and 34.1%, respectively; while, the exhaust exergy loss increased by 43.5%. The FMEP and BSFC decreased by 56.7% and 14.9% as the engine warmed up, while BTE and the exergetic efficiency increased by 5.6% and 5.3%, respectively.

Simplified calculation of friction mean effective pressure for fast simulation of fuel consumption

An environmentally friendly and economical ship operation can be accomplished through many different methods. Most of these approaches focus on technological solutions, e.g. internal engine measures in order to make the engine more eco-friendly, by changing engine control parameters for a better connection between propulsion system and ship, by usage of different fuels or fuel supplements or installation of exhaust gas-treatment systems. For many ships, it is neither efficient nor economically viable to replace or improve existing power generation or propulsion systems in order to improve efficiency or reduce emissions. Some of the internal measures used to reduce NOx-emissions like exhaust gas recirculation even lead to a higher fuel consumption. The vessel itself is still controlled by a crew and they should be kept in the loop to improve efficiency. Therefore optimal operational procedures for handling ships and specifically the outcome of engine manoeuvres is a substantial source for eco-friendly ship operations. The German research project MEmBran (Modelling Emissions and Fuel Consumption during Ship Manoeuvres) addresses especially the basis for optimising ship engine manoeuvres. It focusses on very detailed simulation of the processes of currently existing ship diesel engines, especially in a first step 4-stroke engines in order to implement models in wider comprehensive ship handling simulation software. As part of an existing planning and prediction software that can be used on board, it enables the watch keeping nautical officer and the shipping company to forecast and compare the fuel consumption of the ship for each manoeuvre. In order to reach this goal it is necessary to use fast calculating and stable methods that can be used to forecast the power output of the engine and the fuel consumption. This paper discusses an approach to calculate friction mean effective pressure.

Simulation of bypass electric water pump to reduce the engine warm-up time

There are several strategies have been developed in the automotive cooling system to improve engine thermal management. Basically, these designs use controllable actuators and mechatronic components such as electric water pump, controllable thermostat, and controllable electric fan to improve engine temperature control on most operating ranges. Most of the strategies are complicated and costly. This paper introduced a different approach to improve coolant temperature warm-up during cold start. The new strategy was by promoting a higher coolant flow rate inside the engine block by just installing an electric water pump in the bypass hose. The new approach’s cold start performance was studied using GT-SUITE on a transient model, complete with finite-element of engine block design, lubrication system, components friction model, engine with combustion model and vehicle system. The proposed strategy clearly showed faster coolant temperature increase (18 seconds faster compared to the conventional cooling system). The strategy not only increase the coolant temperature faster, but also increases the oil temperature faster, lower Friction Mean Effective Pressure (FMEP), and lower fuel consumption at certain condition during the warm-up period.

Tribotronic Analysis of Internal Combustion Engine Compression Ring

The influence of operating conditions of the compression rings on the engine power losses affects confoundedly the design of the Internal Combustion Engines (ICEs). Normalized parameters such as Friction Mean Effective Pressure (FMEP) were used to regulate power losses. The purpose of this work was to create a primary control model of the friction mean effective pressure using an automatic control system. This study incorporates the creation of a mixed-hydrodynamic model for the top compression ring in MATLAB computing environment. The load of ring asperities was predicted using Greenwood-Tripp stochastic model. The pressure distribution along the ring face-width was determined using Reynolds equation through finite difference method with the half-Sommerfeld boundary condition for cavitation outlet zone. This was accomplished by finding the maximum ring pressure for a range of engine speeds and lubricant temperatures. Additionally, the computed results concerning the maximum pressure and the PID controlled characteristics are proposed and compared using a cavitation model. Regarding the automatic system, a PID controller was built using SIMULINK. The numerical results showed that FMEP could be the effective parameter in order to control the engine operation and to proof the tribotronics design in an Internal Combustion Engine.

Altitude Performance and Fuel Consumption Modelling of Aircraft Piston Engine Rotax 912 S/ULS

Rotax 912 spark-ignition (SI) naturally aspirated aircraft piston engine is one of the most popular prime movers for the ultra-light weight aircrafts used for short and moderate range flights. SI engines operate at stoichiometric combustion and at high altitude conditions atmospheric pressure is lower than sea level reducing mass of air intake to the engine. At these conditions engine power degrades significantly from sea level, affecting flight parameters such as range and endurance. In order to optimize these parameters, engine power modelling is of vital importance. Within the scope of this study, a thermodynamic SI engine model with performance parameters (break torque and power) and fuel consumption estimation developed in MATLAB/Simulink software. Model tuning is realised using data extracted from Rotax engine operating manual at sea level and high altitude conditions. Model inputs are set as altitude, throttle lever and engine speed. Pressure drop at the intake port is modelled as a function of mass air flow using engine operating manual pressure data at various engine speed points. Mass air flow is determined via employing a volumetric efficiency map based on intake port pressure and engine speed inputs, calibrated using engine operating manual fuel data considering stoichiometric combustion. Compression and expansion strokes area modelled as isentropic events and combustion is modelled as constant volume heat input at top dead centre (TDC). However a combustion efficiency map based on engine speed and fuel flow is employed for the heat input in order to tune the work output of the engine and heat loss to the coolant and exhaust. Pumping loss is calculated based on friction mean effective pressure data. Introduced approach provides high accuracy performance and fuel consumption modelling based on engine operating manual data and can be used for flight parameters optimization studies.

The Estimation of Friction Mean Effective Pressure by Neural Network in a Heavy Duty Diesel Engine

The Estimation of Friction Mean Effective Pressure by Neural Network in a Heavy Duty Diesel Engine

A SI Engine Indicated Characteristics Determination for Gasoline and Methane Operation

The present paper presents a study whose objective is to determine the indicated parameters of an spark-ignition engine and external mixture formation when running on methane and gasoline. The experiments were carried out using optimum adjusting parameters for engine operation on methane and gasoline fuels. The parameters measured and determined are: indicated specific fuel consumption, indicated mean effective pressure, indicated power, indicated efficiency, friction mean effective pressure and etc. over the entire engine speed range. An analysis of the obtained results is made, comparing the obtained indicated parameters at the operation of internal combustion engines with alternative fuel - methane and traditional fuel - gasoline.

Fuel efficiency and exhaust characteristics of turbocharged diesel engine equipped with an electric supercharger

The electric supercharger, which is an important device of the 48 V hybrid system, is known to increase the low-speed efficiency and torque of the internal combustion engine. However, there is a lack of research on exhaust emissions, which are becoming more stringent owing to the use of the electric supercharger. Therefore, this study conducted basic experiments and analysis on the power, fuel efficiency, and exhaust emissions according to the change of engine control parameters during operation of the electric supercharger. The maximum indicated mean effective pressure (IMEP) increase was 52.9% at 1250 rpm. However, friction mean effective pressure (FMEP) and pumping mean effective pressure (PMEP), associated with a loss of engine efficiency, increased under various operating conditions. Brake specific fuel consumption (BSFC) improved by up to 8.8%, and brake specific carbon dioxide (BSCO2) decreased accordingly. Brake specific particulate matter (BSPM) and brake specific oxides of nitrogen (BSNOx) fluctuated significantly with the adjustment of the parameters for engine control. These were partially reduced compared to the conventional engines according to the experimental conditions. Therefore, even if an electric supercharger is applied to a diesel vehicle equipped with exhaust reduction devices, emission regulations can be satisfied.

Mastering the Art of Cylinder Bore Honing

<div class="section abstract"><div class="htmlview paragraph">Honing is a stock removal process intended to perfect bore geometry and size by removing a minimal metal layer while generating a finish pattern to provide optimum lubricant retention. The hone process produces extremely tight tolerances in straightness, roundness, size, and surface finish of cylindrical bores. The material removal is effected by abrasive stones of suitable grit and grade that are expanded against the work surface of the cylinder bore under controlled pressure while being rotated and reciprocated at the same time. Combining these motions produces a characteristic crosshatch pattern with a dedicated surface roughness profile essential for the piston/bore tribology, which in its turn affects the engine performance. Multistep honing processes that combine rough honing with peak or plateau honing are increasingly used to produce state-of-the-art surface finishes without compromising productivity. The outcome of the honing process - not only in terms of the GD&T but also the tribology of the finished component - depends on a great number of parameters including the machine type, working conditions, tools, process fluid, and most importantly the operator experience. As the piston/bore tribology is concerned, mechanochemical processes offers significant advantages over conventional mechanical processes. Thus, the mechanochemical finishing of cylinder bores using the Triboconditioning® process allows one to reduce friction mean effective pressure of the piston/bore system by 5 to 15% at the same time significantly reducing piston ring wear, blowby and oil consumption.</div></div>

An experimental investigation on combustion and performance characteristics of supercharged HCCI operation in low compression ratio engine setting

This study investigates the effects of boost pressure on combustion and performance of an early direct injection homogenous charge compression ignition (HCCI) engine at a low compression ratio (CR). A 2.0 L, four-cylinder, four-stroke, gasoline direct injection engine was converted to operate in early direct injection HCCI mode. In addition, a supercharger unit was developed for engine boosting. The experiments were performed at different intake manifold absolute pressures (MAP) from 1.0 to 1.6 bar at different engine loads using n-heptane fuel. The effects of boost pressure were investigated on HCCI combustion and engine performance characteristics using volumetric efficiency, in-cylinder pressure, heat release rate (HRR), maximum in-cylinder pressure and gas temperature, CA50 (crank angle by which 50% of the fuel is burnt), combustion duration, apparent combustion efficiency, indicated mean effective pressure (IMEP), brake mean effective pressure (BMEP), friction mean effective pressure (FMEP), indicated thermal efficiency (ITE), brake thermal efficiency (BTE), heat loss, exergy of heat loss, coefficient of variation of IMEP (COVIMEP), maximum pressure rise rate (MPRR) and ringing intensity (RI). The experimental results showed that high-efficiency HCCI operation is feasible at an engine compression ratio as low as 9.2 once the engine variables are properly optimized and an appropriate level of supercharging is utilized. An increase in indicated thermal efficiency was seen as boost pressure increased. In addition, combustion phasing advanced by increasing boost pressure or increasing air–fuel equivalence ratio values. Combustion events with CA50 2–3 °CA aTDC show the highest thermal efficiency especially at low boost pressure conditions. In addition, the pressure rise rate and ringing intensity increased by increasing air–fuel equivalence ratio and MAP. The test results also showed that HCCI operating range can be extended with the increase of intake manifold pressure especially at high load limits.

Experimental test and thermodynamic analysis on scaling-down limitations of a reciprocating internal combustion engine.

Due to the enormous energy densities of liquid hydrocarbon fuels for future utilization on micro scale, there is a concern about the feasibility of scaling down reciprocating internal combustion engines from small scale to meso scale. By building a specialized test bench, the performance and combustion characteristics of a miniature internal combustion engine with a displacement of 0.99 cc were tested, and the thermodynamic simulation was carried out to achieve a more complete understanding of in-cylinder mass and energy change of the miniature internal combustion engine. The miniature internal combustion engine had higher brake-specific fuel consumption, lower thermal efficiency, lower brake mean effective pressure, and serious cyclic variation; however, friction mean effective pressure seems to be less sensitive to engine speed. Simulation results showed that the miniature internal combustion engine had a poor volumetric efficiency, which was not more than 50%. The step-by-step processes of scaling down the miniature internal combustion engine were also simulated; it was found that the maximum indicated mean effective pressure loss was due to the imperfection of gas exchange processes, and the next was the imperfection of combustion. It is considered that for the scaled-down miniature internal combustion engines, more attention should be pay on improving the processes of gas exchange and combustion, and achieving meso-scale internal combustion engines with cylinder bore less than 1 mm is thermodynamically possible in future if these imperfections, especially that of the gas exchange process, can be effectively perfected.

Engine Performance and Emissions Analysis in a Cold, Intermediate and Hot Start Diesel Engine

Presented in this paper is an in-depth analysis of the impact of engine start during various stages of engine warm up (cold, intermediate, and hot start stages) on the performance and emissions of a heavy-duty diesel engine. The experiments were performed at constant engine speeds of 1500 and 2000 rpm on a custom designed drive cycle. The intermediate start stage was found to be longer than the cold start stage. The oil warm up lagged the coolant warm up by approximately 10 °C. During the cold start stage, as the coolant temperature increased from ~25 to 60 °C, the brake specific fuel consumption (BSFC) decreased by approximately 2% to 10%. In the intermediate start stage, as the coolant temperature reached 70 °C and the injection retarded, the indicated mean effective pressure (IMEP) and the brake mean effective pressure (BMEP) decreased by approximately 2% to 3%, while the friction mean effective pressure (FMEP) decreased by approximately 60%. In this stage, the NOx emissions decreased by approximately 25% to 45%, while the HC emissions increased by approximately 12% to 18%. The normalised FMEP showed that higher energy losses at lower loads were most likely contributing to the heating of the lubricating oil.

Emissions and performance with diesel and waste lubricating oil: A fundamental study into cold start operation with a special focus on particle number size distribution

This study investigates the effect of engine temperature during cold start and hot start engine operation on particulate matter emissions and engine performance parameters. In addition to a fundamental study on cold start operation and the effect of lubricating oil during combustion, this research introduces important knowledge about regulated particulate number emissions and particulate size distribution during cold start, which is an emerging area in the literature. A further aspect of this work is to introduce waste lubricating oil as a fuel. By using diesel and two blends of diesel with 1 and 5% waste lubricating oil in a 6-cylinder turbocharged engine on a cold start custom test, this investigation studied particle number (PN), friction losses and combustion instability with diesel and waste lubricating oil fuel blends. In order to understand and explain the results the following were also studied: particle size distribution and median diameter, engine oil, coolant and exhaust gas temperatures, start of injection, friction mean effective pressure (FMEP), mechanical efficiency, coefficient of variation (CoV) of engine speed, CoV of indicated mean effective pressure (IMEP) and maximum rate of pressure rise were also studied. The results showed that during cold start the increase in engine temperature was associated with an increase in PN and size of particles, and a decrease in FMEP and maximum rate of pressure rise. Compared to a warmed up engine, during cold start, PN, start of injection and mechanical efficiency were lower; while FMEP, CoV of IMEP and maximum rate of pressure rise were higher. Adding 5% waste lubricating oil to the fuel was associated with a decrease in PN (during cold start), decreased particle size, maximum rate of pressure rise and CoV of IMEP and was associated with an increase in PN and nucleation mode particles (during hot start) and FMEP.

Effect of surface texture on the improvement of tribological performance of ring‐deformed liner conjunction under different oil supplies

AbstractIn this work, a tribological performance analysis is numerically conducted for a surface‐textured ring‐deformed liner conjunction. In the analysis, three different distribution patterns of surface texture are designed and machined on the surface of ring. To evaluate the frictional properties of the textured rings under mixed lubrication regime, a transient lubrication model considering the oil film thermal effect is developed. Meanwhile, to evaluate the oil film consumption and the transition of lubrication condition in an engine cycle, an oil transport model is built to determine the boundary positions of lubrication zone. Based on the models, the oil consumption, MOFT (minimum oil film thickness), friction force, power loss, and FMEP (friction mean effective pressure) value of the textured ring are studied under different oil supplies. The frictional characteristics of the rings with various distribution patterns of surface texture are also analyzed and compared. The results show that the edge‐textured ring can improve the tribological performance significantly, and the improvement varies with the oil supply.

Study of Break-In Process and its Effects on Piston Skirt Lubrication in Internal Combustion Engines

The piston skirt is one of the main contributors to the total mechanical loss in internal combustion engines. Usually, the skirt friction experiences a rapid change during the break-in period largely due to the wear of the machine marks or roughness against soft coatings. It is thus important to consider the effect of the change of the roughness for a realistic prediction of the piston skirt friction and system optimization. In this work, an existing model of piston skirt lubrication was improved with the consideration of a breaking in process for the most commonly used triangle machine marks. A new set of flow factors in the averaged Reynolds equation were analytically derived for the trapezoid shape formed after wear of the original triangle shape. A new asperity contact model was developed for the trapezoid shape. The calculation results reflect the trend of friction mean effective pressure (FMEP) during break-in in an engine test and showed quantitative agreement under the same amount of wear.

Further Experimental Investigation of Motored Engine Friction Using Shunt Pipe Method

<div class="section abstract"><div class="htmlview paragraph">Mechanical friction is a significant power dissipater in the internal combustion engine. In the effort of designing more efficient and less pollutant engines, friction reduction is certainly on the agenda to be investigated. Such investigation cannot be possible without an accurate measurement of the same quantity. This publication regards a continued study on the mechanical friction determination in an internal combustion engine using the Pressurised Motoring Method. In this work, the friction mean effective pressure of a four-cylinder compression ignition engine was investigated with varying engine speed and manifold pressurisation, using a dedicated high precision sensor for the correct determination of the cylinder Top Dead Centre position. Two different measurement sessions were carried out; in the first, air was employed as pressurisation medium, testing 32 different setpoints; in the second, instead, with the aim to test the effect of the variation of thermochemical properties of fluids on the thermodynamic loss angle, Argon was used in place of air in 18 different setpoints. In the motored condition it is widely accepted that the brake torque is a measure of the losses of the engine and therefore has to be supplied by the driver, in our case the AC motor. The 2000 rpm region was explored with the aim to investigate the high motoring brake torque observed in a previous work from the same authors [<span class="xref">1</span>]. An investigation of the volumetric efficiency effect on motoring brake torque is also presented in the paper. Values of IMEP, BMEP, FMEP, peak in-cylinder pressure, loss angle and other parameters are given. The loss angle measured at each setpoint using the TDC sensor is compared with the loss angle evaluated by the use of two thermodynamic methods developed by Stas’ [<span class="xref">2</span>] and Pipitone [<span class="xref">3</span>].</div></div>

EXPERIMENTAL STUDY INDICATORS IN SMALL-DISPLACEMENT ENGINE FORCOMPACT TRACTOR

Problem. Engine selection for a specific type of transport vehicle, configuration and refinement of mathematical models of processes, improvement of engine construction are produced based on the results of experimental researches. However, in technical literature, and even the information resources of the manufacturers it is provided very limited information about the small-displacement motors. In addition, the available data often contradict each other. Goal of the article: experimental research of fuel efficiency and toxicity of exhaust gases of the small-displacement engine Briggs & Stratton Vanguard 18HP at different loads and speeds. Methodology. The engine performance parameters were evaluated on the experimental set-up of the internal combustion engines department of National Technical University "Kharkiv Polytechnic Institute". Characteristics of the engine on the modes with speeds 1800, 2400, 3000, 3600 rpm and loads from idle to maximum were obtained. As a result of experimental data processing it were determined volumetric efficiency and air/fuel ratios. Total friction mean effective pressure was obtained by extrapolation the plot of fuel consumption versus brake output back to zero fuel consumption. Results. The impact of engine load and speed on the parameters of the fuel efficiency and emissions of the engine was analyzed. It is shown that the level of motoring losses in the small-displacement engine Briggs&Stratton Vanguard 18 HP corresponds to the motoring losses in gasoline engines with greater volume and speed. The empirical equation for determining total friction mean effective pressure in the engine was proposed. It is shown that formula proposed by V.G.Dyachenko provides satisfactory accuracy of determining total friction mean effective pressure. Originality of work consists in the proposed empirical dependence of total friction mean effective pressure from the engine speed for small-displacement engine. Рractical value consists in the parameters of the small-displacement engine at operating speeds, the assessment of the applicability of the different empirical dependencies for evaluation of the motoring losses in the small-displacement engine.