Performa pada Motor Bakar 6-Langkah dengan Langkah Power Ekspansi sampai Titik Mati Bawah

This study aims are to observe the performance of a six-stroke combustion motor and to analyze the thermodynamics of a six-stroke combustion engine with a power expansion step to the bottom dead center. The fuel used in this observation is pertalite with a RON 90 value. The method used is a true experimental method, with independent variables, namely 35%, 40%, 45%, and 50% throttle openings with loading on the prony disc brake of 10 kg, 20kg, 30kg, 40kg, and 50kg. In the torque data, each throttle opening shows the highest number of 7.26 (Nm) with a load of 50kg and the lowest value of 2.01 (Nm) with a load of 10kg, for effective power the highest value is 8.47 (kW) at 50% throttle opening with load is 40kg and the lowest value is 2.49 (kW) at 35% throttle opening with a load of 10kg, while for the specific fuel consumption (SFC) the highest value is 4.28 (kg/Hp.h) at 40% throttle opening with a load of 10kg and the lowest value is 0.77 (kg/Hp.h) at 50% throttle openings with a load of 50kg, and for the thermal efficiency of the six-stroke motor, which means an average increase of 14.58% compared to the thermal efficiency of the conventional 4-stroke internal combustion engine.

Free Stream Behavior of Hydrogen Released from a Fluidic Oscillating Nozzle

The H2 internal combustion engine (ICE) is a key technology for complete decarbonization of the transport sector. To match or exceed the power density of conventional combustion engines, H2 direct injection (DI) is essential. Therefore, new injector concepts that meet the requirements of a H2 operation have to be developed. The macroscopic free stream behavior of H2 released from an innovative fluidic oscillating nozzle is investigated and compared with that of a conventional multi-hole nozzle. This work consists of H2 flow measurements and injection tests in a constant volume chamber using the Schlieren method and is accompanied by a LES simulation. The results show that an oscillating H2 free stream has a higher penetration velocity than the individual jets of a multi-hole nozzle. This behavior can be used to inject H2 far into the combustion chamber in the vertical direction while the piston is still near bottom dead center. As soon as the oscillation of the H2 free stream starts, the spray angle increases and therefore H2 is also distributed in the horizontal direction. In this phase of the injection process, spray angles comparable to those of a multi-hole nozzle are achieved. This behavior has a positive effect on H2 homogenization, which is desirable for the combustion process.

Kinematic synthesis method and eccentricity effects of a Stephenson mechanism

When implementing the technological process on crank presses, it is necessary to provide a predetermined working cycle of the slider motion: fast lifting, dwell, and slow lowering. The cycle cannot be realized without controlling the motor. In addition, using controllable motors increases the manufacturing cost. Due to the geometric and kinematic capabilities of the mechanism, changing the kinematics of the working link is the best choice. Thanks to the use of the Stephenson II mechanism, the slider skew is eliminated due to the parallel connecting rods and the increased area of slider contact. This study presents a numerical method for kinematic synthesis of the Stephenson mechanism that has kinematic advantages. The method is based on mean square deviation which is the minimizing of an objective function. Thanks to the proposed synthesis method, approximate dwell movement can be performed when the slider is on the bottom dead center. In this study, values of the crank length and parallel connecting rods' lengths, angular coordinates of the crank and connecting rods, and the eccentricity of the guide slider relative to the crank rotation axis were obtained. It is observed that eccentricity affects the lower forward and higher backward speed of the slider. The kinematic results of the slider movement are comparatively presented in this article.

Decomposition analysis and peak stagger design for Crank-triangular linkage-elbow mechanism of mechanical servo presses

High mechanical advantage as well as low and steady slide speed within the working stroke Sn are the fundamental requirements for the working mechanism of servo-mechanical press. Currently, the Crank-Triangular Linkage-Elbow (CTLE) mechanism has attracted more and more attention from researchers and manufacturers of servo presses. This paper presents a new analysis and design method of CTLE. The mechanism is decomposed into two sub-units: crank and triangular-linkage elbow, followed by the kinematic and force analysis of each sub-unit. The influences of each structural parameter on the working performance are obtained and can be used as the basis for preliminary design. Through the offset design, the mechanical advantage peaks of the two units, MA1max and MA2max, do not occur at the same time: MA1max is located near Sn, while MA2max is just at BDC (Bottom Dead Center). Because the mechanical advantage of the whole mechanism is the product of the two subunits, the designed mechanism can obtain high and steady mechanical advantage together with low and steady slide speed within Sn. After preliminary design, the scheme can be further modified by numerical simulation and optimization. Hence the design efficiency can be improved.

Field-Testing of Biodiesel (B100) and Diesel-Fueled Vehicles: Part 3—Wear Assessment of Liner and Piston Rings, Engine Deposits, and Operational Issues

This study investigated the use of biodiesel (B100) and baseline mineral diesel in two identical unmodified vehicles to realistically assess different aspects of biodiesel’s compatibility and durability issues with modern common rail direct injection (CRDI) engine-powered vehicles. Two identical vehicles were operated for 30,000 km under identical operating conditions during a field-trial using biodiesel (B100) and mineral diesel. Exhaustive experimental results from this series of tests are divided into four sections, and this is the third paper of this series of four papers, which covers comparative feasibility and wear analyses, underlining the effect of long-term use of biodiesel on wear of cylinder liner and piston rings compared to baseline mineral diesel-fueled vehicle. Surface microstructures at three locations of the cylinder liner were evaluated using scanning electron microscopy (SEM). Wear was found to be relatively lower at all locations of liners from biodiesel-fueled vehicle compared to diesel-fueled vehicle. Surface roughness of cylinder liners measured at different locations showed that it reduced by ∼30–40% at top dead center (TDC), ∼10–20% at mid-stroke, and ∼20–30% at bottom dead center (BDC) for both vehicles, showing higher wear close to TDC compared to mid-stroke and BDC locations. Loss of piston-ring weight was significantly lower for biodiesel-fueled vehicle. Engine tear-down observations and carbon deposits on various engine components were recorded after the conclusion of the field trials. During these field-trials, engine durability-related issues such as fuel-filter plugging, injector coking, piston-ring sticking, carbon deposits in the combustion chamber, and contamination of lubricating oils were found to be relatively lower in biodiesel-fueled vehicle. Overall, no noticeable durability issues were recorded because of the use of biodiesel in CRDI engine-powered vehicle.

Study of the conrod deformation during piston interaction with liquid in the internal combustion engine cylinder

The paper analyzes the deformation of the connecting rod stem with buckling due to water ingress into the internal combustion engine cylinder (the so-called hydrolock). A method is presented that has been developed to perform calculations of stem deformation in the process of compressing air with liquid in an internal combustion engine cylinder. The method is based on solving a system of differential equations for pressure and temperature in the cylinder, followed by calculating the compression force acting on the connecting rod. A carried-out simulation of the compression process demonstrates the dependence of the air pressure in the cylinder, the stress and the strain of the connecting rod on the fill ratio of the combustion chamber with liquid. The calculations performed according to the classical theory of resistance of materials have shown that the connecting rod with the buckling of the stem begins to deform when the liquid fills the combustion chamber to a minimum of 80%. With the increase in the amount of liquid, the deformation of the conrod increases, and when the level of liquid filling is so significant that it exceeds the volume of the combustion chamber, the conrod stem deformation reaches extreme values. It is shown that under these conditions after the hydrolock occurs the engine may fail due to the piston wedging the crankshaft in the bottom dead center position.

Effect of the Intake Valve Lift and Closing Angle on Part Load Efficiency of a Spark Ignition Engine

This study provides an experimental evaluation of the effectiveness of Miller cycles with various combinations of lift and intake valve closing angle for a passenger car engine with premixed combustion in naturally aspirated operation. A fully variable electro-hydraulic valve train provided different valve lift profiles. Six load points, from 1.5 up to 5 bar brake mean effective pressure at a constant engine speed of 2000 min−1, were tested with 6 different intake valve lift/intake valve closing angle combinations. The intake valve closing angle was always set before bottom dead center to achieve the desired load with unthrottled operations. Experimental comparison with throttled operation outlines an indicated efficiency increase of up to 10% using high intake lift with early valve closing angle. Furthermore, this analysis outlines the influences that early intake valve closing angle has on fuel energy disposition. Longer combustion duration occurs using early intake valve closing angle because of turbulence dissipation effects, leading to slight reductions in the heat-to-work efficiency. However, overall pressure and temperature levels decrease and consequently heat losses and losses due to incomplete combustion decrease as well. Overall, we found that combustion deterioration is compensated/mitigated by the reduction of the heat losses so that reductions of pumping losses using early intake valve closing can be fully exploited to increase the engine’s efficiency.

PENGARUH INTAKE DAN EXHAUST LOBE LIFT SERTA CELAH KATUP TERHADAP KONSUMSI BAHAN BAKAR

Abstrak: Sepeda motor membutuhkan bahan bakar fosil dan saat ini cadangannya semakin berkurang serta tidak dapat diperbarui. Dengan kondisi saat ini, perlu untuk mengontrol penggunaan bahan bakar pada sepeda motor. Pengaturan intake lobe lift, exhaust lobe lift dan celah katup berdampak positif pada konsumsi bahan bakar. Tujuan dari penelitian ini adalah untuk menguji pengaruh pengaturan intake lobe lift, exhaust lobe lift dan celah katup terhadap konsumsi bahan bakar pada sepeda motor Honda Supra 125. Metode penelitian menggunakan metode eksperimental. Hasil penelitian menunjukkan bahwa ada pengaruh variasi intake lobe lift, exhaust lobe lift dan celah katup terhadap konsumsi bahan bakar. Konsumsi bahan bakar terlama (irit) yaitu pada modifikasi camshaft intake lobe lift 250 sebelum Titik Mati Atas (TMA) dan exhaust lobe lift 450 setelah Titik Mati Bawah (TMB), celah katup masuk (in) adalah 0,15 mm dan keluar (ex) adalah 0,15 mm. Abstract: Motorcycles need fossil fuels and currently reserves were decreasing and cannot be renewed. Under current conditions, it is necessary to control fuel use on motorbikes. The intake lobe lift, exhaust lobe lift and valve gap settings have a positive impact on fuel consumption. The purpose of this study was to examine the effect of regulating intake lobe lifts, exhaust lobe lifts and valve fissures on fuel consumption on Honda Supra 125 motorcycles. The research method used experimental methods. The results showed that there was an effect of variations in intake lobe lift, exhaust lobe lift and valve gap on fuel consumption. Economical fuel consumption is the modification of the intake lobe lift camshaft 250 before Top Dead Center (TDC) and exhaust lobe lift 450 after Bottom Dead Center (BDC), valve gap in 0.15 mm and ex 0.15 mm.