Combustion Characteristics According to the Chemical Composition of Land Fill Gas

This study was conducted using the existing ignition device to verify the effectiveness of LFG, a renewable energy source. The experimental method used a constant volume combustion chamber to check the flame propagation process and combustion pressure. The experiment was carried out by changing the fuel composition ratio of LFG in the range of LFG70 to LFG40. From the result, it was found that the methane combustion occurred smoothly in LFG70 during the flame propagation process, and that combustion progressed gradually over time. In the LFG60 and LFG50 regions, which are fuels with a high CO2 ratio, it was confirmed that the combustion slowed down and the brightness of the light decreased at the same time. In LFG40 with 40% of CH4, a misfire phenomenon in which combustion does not occur was discovered. For combustion pressure, the CH4 chemical composition of the LFG was lowered, which led to the combustion delay and the reduction of combustion pressure

Wear Analysis of a Low-Speed Diesel Engine Connecting Rod Based on Orthogonal Simulation Test

As con-rod is a critical component in an engine, its reliability overwhelmingly directly affects the performance of the whole diesel engine. The fretting wear of con-rod bushing mainly occurs on the contact surface with con-rod small end and con-rod small end cap. In the proposed study, the contact process of con-rod small end, con-rod small end cap and bushing under maximum combustion pressure condition was analyzed, and the distribution of contact pressure and friction stress was analyzed. Then the orthogonal simulation test was designed. According to the contact mechanics theory, the interference amount and friction coefficient of the contact surface were taken as the test factors, and the maximum contact pressure and friction stress under the maximum combustion pressure condition were taken as the objective functions. The influence of the test factors on the objective function was analyzed, and the most reasonable interference amount and friction coefficient were found, so as to slow down the fretting wear of the con-rod bushing.

Acoustic emissions in the valuation of the combustion chamber pressure of an engine

Internal combustion engines demand advanced monitoring methodologies to promote efficient operation; particularly, the combustion pressure plays a central role in the overall performance, which promotes the utilization of transducers that hinders. Therefore, the present study introduces an acoustic emission methodology that serves for indirect combustion pressure measurements. Accordingly, the compound methodology integrates the Hilbert transform and the complex cepstrum using neural networks to accomplish pressure signal reconstruction. Results demonstrated that the proposed methodology featured robust performance while estimating pressure signals as it mitigates the combined noise effect produced by variations in engine speed, engine load, and fuel type. Moreover, the reconstructed signal facilitated the determination of key performance parameters such as peak pressure, pressure timing, and effective mean pressure. Relative error amounted to less than 10%, which ratified the robustness of the indirect pressure measurements. In conclusion, acoustic signal techniques represent an adequate approach to estimate the combustion pressure at variable engine conditions.

COMPARISON OF COMBUSTION INDICATORS OF TWO-STROKE ENGINES WITH A CARBURETOR AND DIRECT FUEL INJECTION

The subject matter of study in the article is the indicators of the combustion process of a two-stroke engine 1D 8.7 / 8.2 with spark ignition when using a carburetor power supply system (external mixture formation) and a direct fuel injection system (internal mixture formation). Internal mixture formation ensures the organization of a stratified fuel-air charge (SFAC) and a stratified lean fuel-air charge (SLFAC). Combustion indicators allow you to assess the nature of the combustion process. The goal is to determine the nature of the change in the combustion indicators of the engine with external and internal mixture formation during the organization of the working process with the SFAC and SLFAC at the load characteristic modes (n = 3,000 rpm). The tasks to be solved are as follows. The use of internal mixture formation and the organization of the combustion of SLFAC and SFAC made it possible to obtain values of ηi greater than with external mixture formation at all modes of the load characteristic. The maximum value of ηi for SLFAC is 0.5 at a load bmep = 0.2 MPa, for SFAC – 0.44 at bmep = 0.25 MPa and 0.3 at bmep = 0.36 MPa for an engine with a carburettor. Maximum combustion pressure (рz), pressure increase ratio (λ), preliminary expansion ratio (ρ), further expansion ratio (δ), combustion character indicator (m), maximum heat release rate (dx / dfi max), duration of combustion from TDC to point Z (φz), total duration of combustion (dφz); to construct the characteristics of changes in combustion indicators and to obtain empirical dependences depending on the engine load. An experimental-analytical research method is used, which provides for the determination of the nature and analysis of the course of the combustion process according to the combustion indicators established by the experimental indicator diagrams. The following results were obtained. The use of internal mixture formation and the organization of the combustion of SFAC and SLFAC made it possible to obtain ηi values greater than with external mixture formation at all modes of the load characteristic. The maximum value of ηi for SLFAC is 0.5 at a load ре = 0.2 MPa, for SFAC - 0.44 at ре = 0.25 MPa and 0.3 at ре = 0.36 MPa for an engine with a carburetor. The pressure in the cylinder with the piston position at TDC is on average 1.5 times higher for an engine with a carburetor, and the maximum combustion pressure рz is higher up to 11 % with the organization of SLFAC (the degree of pressure increase λ is reduced by 26 %) and 20-22 % higher than in the organization of SFAC (the value of λ is reduced by 31 %). An increase in the compression ratio ε by 26.4 % and a decrease in the degree of preliminary expansion ρ at SLFAC in comparison with SFAC made it possible to increase the degree of further expansion δ by an average of 30 % and by 43 % in comparison with the carburetor power system. When organizing SLFAC, the value of the indicator of the nature of combustion m is, on average, 1.4 times higher than that of an engine with a carburetor and 1.45 times higher relative to the organization of SFAC, at which the maximum rate of heat release dx / dfi max is up to 40 % higher than in the engine with carburetor. The SLFAC organization allowed reduce the combustion duration by 39 % relative to external mixture formation and by 36 % relative to the SFAC organization. Conclusions. The scientific novelty of the results obtained consists in obtaining data and empirical dependences of the indicators of the combustion process of the 1D 8.7 / 8.2 engine with external and internal mixture formation with the organization of SFAC and SLFAC at load characteristic modes (n = 3,000 rpm). It was found that the best technical, economic and environmental indicators correspond to the organization of internal mixing with SLFAC.

Study on the Influence of EGR on the Combustion Performance of Biofuel Diesel at Different Ambient Simulated Pressures

In order to explore the influence of EGR at different altitudes on the performance of biofuel diesel engines, a comparative experimental study is conducted with the biodiesel–ethanol–diesel B15E5 (biodiesel with 15% volume fraction, ethanol with 5% volume fraction and diesel with 80% volume fraction) mixed fuel at different EGR rate and different atmospheric pressure. The experimental results show that diesel engine power performance and economy goes up with the increase of atmospheric pressure, and it decreases with the increase of EGR rate. At 2200 rpm, the improvement range of medium and high diesel engine load is 1.5–6.8%, and that of 1800 rpm is 2.8–11.7%. At the same atmospheric pressure, with the increase of EGR rate, the power and economy turn worse. The peak combustion pressure and heat release rate both increased with the increase of the atmospheric pressure at full load. At the same atmospheric pressure, peak combustion pressure and peak heat release rate fall with the increase of EGR rate. At part load, firstly, smoke emissions fall with the increase of the load and then rise. As the atmospheric pressure goes up, the smoke emissions show a downward trend, with a decline of 6.6–40%, while the NOx emissions show a rising trend, with an increase of 1.2–8.5%. At the same atmospheric pressure, the smoke emission increase with the increase of EGR rate by 9–12.5%, and the NOx emissions increase with the decrease of EGR rate by 2.5–6.8%. The HC and CO Emissions decrease with the increase of atmospheric pressure. HC emission decreases by 9.3–19.1%, and CO emission decreases by 2.9–16.6%. At the same atmospheric pressure, the HC emission decreases with the increase of the EGR rate by 3.3–4.5% at medium and high loads, and the CO emission increases with the EGR rate by 3.1–4.5%.

Combustion Characteristics of Multi-Element Swirl Coaxial Jet Injectors under Varying Momentum Ratios

The combustion characteristics of a staged combustion cycle engine with an oxidizer-rich preburner were experimentally studied at different momentum ratios of multi-element injectors. Propellants were simultaneously supplied as a liquid–liquid–liquid system, and an injector was designed in which a swirl coaxial jet is sprayed. The injector burned the propellants in the inner chamber which had a temperature greater than 2000 K. To cool the combustion gas, a liquid oxidizer was supplied to the cooling channel outside the injector. To prevent the turbine blades from melting, the temperature of the combustion gas was maintained below 700 K. To confirm the combustion characteristics at different momentum ratios of the high-temperature combustion gas inside the injector and the low-temperature liquid oxidizer outside the injector, three types of injectors were designed and manufactured with different momentum ratios: MR 3.0, MR 3.3, and MR 3.7. In this study, the results of the combustion test for each type were compared for 30 s. For ORPB-A, a combustion pressure of 18.5 MPaA, fuel mass flow rate of 0.26 kg/s, oxidizer mass flow rate of 15.3 kg/s, and turbine inlet temperature of 686 K were obtained in the combustion stability period of 29.0–29.5 s. The combustion efficiency was 98% for MR 3.0 (ORPB-A), which was superior to that for other momentum ratios. In addition, during the combustion test for MR 3.0, the fluctuations in the characteristic velocity, combustion pressure, and propellant mass flow rate were low, indicating that combustion was stable. The three types of combustion instability were all less than 0.8%, thus confirming that the combustion stability was excellent.

Engine Combustion: Pressure Measurement and Analysis

Engine Combustion: Pressure Measurement and Analysis, 2E provides practical information on measuring, analyzing, and qualifying combustion data, as well as details on hardware and software requirements and system components. Describing the principles of a successful combustion measurement process, the book will enable technicians and engineers to efficiently generate the required data to complete their development tasks. The revised edition has been updated with color photos and a fresh modern format has been adapted enhancing the readability of the book. As with the original printing, Engine Combustion: Pressure Measurement and Analysis, 2E is a comprehensive handbook for technicians and engineers involved in engine testing and development, and a valuable reference for scientists and students who wish to understand combustion measurement processes and techniques.