Explore the vast range of titles available.

The co-combustion of diesel with alcohol fuels in a compression ignition dual fuel engine is one of the ways of using alternative fuels to power combustion engines. Scientific explorations in this respect should not only concern the combustion process in one engine cycle, which is most often not representative for a longer engine life, but should also include an analysis of multiple cycles, which would allow for indicating reliable parameters of engine operation and its stability. This paper presents experimental examinations of a CI engine with a dual fuel system, in which co-combustion was performed for diesel and two alcohol fuels (methanol and ethanol) with energy contents of 20%, 30%, 40% and 50%. The research included the analysis of the combustion process and the analysis of cycle-by-cycle variation of the 200 subsequent engine operation cycles. It was shown that the presence and increase in the share of methanol and ethanol used for co-combustion with diesel fuel causes an increase in ignition delay and increases the heat release rate and maximum combustion pressure values. A larger ignition delay is observed for co-combustion with methanol. Based on changes in the coefficient of variation of the indicated mean effective pressure (COVIMEP) and the function of probability density of the indicated mean effective pressure (f(IMEP)), prepared for a series of engine operation cycles, it can be stated that the increase in the percentage of alcohol fuel used for co-combustion with diesel fuel does not impair combustion stability. For the highest percentage of alcohol fuel (50%), the co-combustion of diesel with methanol shows a better stability.

Techniques such as exhaust gas recirculation (EGR) and water-in-fuel emulsions (WFEs) can significantly decrease NOx emissions in diesel engines. As a disadvantage of adopting EGR, the afterburning period lengthens owing to a shortage of oxygen, lowering thermal efficiency. Meanwhile, WFEs can slightly reduce NOx emissions and reduce the afterburning phase without severely compromising thermal efficiency. Therefore, the EGR–WFE combination was modeled utilizing the KIVA-3V code along with GT power and experimental results. The findings indicated that combining EGR with WFEs is an efficient technique to reduce afterburning and enhance thermal efficiency. Under the EGR state, the NO product was evenly lowered. In the WFE, a considerable NO amount was created near the front edge of the combustion flame. Additionally, squish flow from the piston’s up–down movement improved fuel–air mixing, and NO production was increased as a result, particularly at high injection pressure. Using WFEs with EGR at a low oxygen concentration significantly reduced NO emissions while increasing thermal efficiency. For instance, using 16% of the oxygen concentration and a 40% water emulsion, a 94% drop in NO and a 4% improvement in the Indicated Mean Effective Pressure were obtained concurrently. This research proposes using the EGR–WFE combination to minimize NO emissions while maintaining thermal efficiency.

The present study focuses on evaluating split-injection strategies in an ammonia–diesel dual-fuel (ADDF) engine at 1800 rpm under medium load conditions, a load range of particular interest in stationary engine operation, with the broader goal of improving combustion stability and efficiency when operating near a 50% ammonia energy contribution. Medium-load ADDF operation, particularly in small compression ignition (CI) engines, remains sparsely explored, and the influence of diesel split injections on combustion phasing and efficiency is not well understood. In this study, a twin-cylinder common rail direct injection (CRDI) diesel engine was operated in ADDF mode at 1800 rpm and medium load, with ammonia energy share of approximately 50%. A systematic experimental investigation was conducted by varying pilot injection ratio (PIR) up to 50% and pilot injection timing from 46 to 66 crank angle degrees before top dead center (CAD BTDC), while maintaining a fixed main injection timing. The experiments were complemented with computational fluid dynamics (CFD) simulations using CONVERGE v3.0 to analyze in-cylinder combustion behavior. Results show that an optimized split-injection strategy (PIR of 20% and pilot timing of 60 CAD BTDC) significantly improves combustion efficiency (~ 95%) and enhances brake thermal efficiency under ADDF operation. Further increase in PIR leads to efficiency deterioration due to unfavorable combustion phasing. The pressure and heat release characteristics reveal a shift toward low-temperature combustion with reduced peak pressure compared to diesel-only operation, attributed to the higher specific heat capacity of ammonia. The optimized split strategy advances CA50, reduces combustion duration, and minimizes negative work, thereby improving overall combustion performance. OH-radicals from simulation corroborate a hierarchy of high-temperature reaction intensity: diesel-only > ADDF split > ADDF single. Stability remained acceptable with controlled COV of IMEP under 3%. This study provides an integrated experimental-CFD evaluations of split diesel injection for a medium-load ADDF engine, and identifies an optimized pilot-main injection strategy capable of enhancing ammonia utilization while mitigating efficiency penalties. These findings offer actionable guidance for ADDF operation in power generation sector and other medium-load CI applications.

In this paper, an opposed-piston two-stroke (OP2S) gasoline direct injection (GDI) engine is introduced and its working principles and scavenging process were analyzed. An optimization function was established to optimize the scavenging system parameters, include intake port height, exhaust port height, intake port circumference ratio, the exhaust port circumference ratio and opposed-piston motion phase difference. The effect of the port height on the effective compression ratio and effective expansion ratio were considered, and indicated mean effective pressure (IMEP) was employed as the optimization objective instead of scavenging efficiency. Orthogonal experiments were employed to reduce the calculation work. The effect of the scavenging parameters on delivery ratio, trapping ratio, scavenging efficiency and indicated thermal efficiency were calculated, and the best parameters were also obtained by the optimization function. The results show that IMEP can be used as the optimization objective in the uniflow scavenging system; intake port height is the main factor to the delivery ratio, while exhaust port height is the main to engine trapping ratio, scavenging efficiency and indicated thermal efficiency; exhaust port height is the most important factor to effect the gas exchange process of OP2S-GDI 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.

Abstract This pioneering study focused on evaluating four distinct compositions, in addition to standard gasoline, within a spark ignition engine, following the rigorous specifications of the DIN70020 standard, under full load conditions. The meticulously conducted tests involved the introduction of varying volumes of isooctane (10%, 20%, 30%, and 40%) into the mixture, thus opening new perspectives on performance and combustion characteristics in a realistic engine operation context. The addition of isooctane, a key component of commercial unleaded gasoline, presents significant advantages in the context of spark ignition engines. This is primarily due to the high vaporization enthalpy of isooctane, a property that directly impacts combustion processes. Indeed, this characteristic reduces the maximum temperature reached in the engine cylinder, thereby contributing to a notable decrease in nitrogen oxides (NOx) emissions. Rigorous experiments demonstrated a significant reduction in emissions, reaching up to 5% for the I10 blend (10% isooctane +90% commercial unleaded gasoline), accompanied by a notable improvement in the maximum value of the indicated mean effective pressure and overall efficiency. These empirical findings were corroborated by numerical simulations using the DIESL-RK software, revealing an average convergence of results ranging from 0.47% to 3.92%. This combination of experimental approaches and numerical modeling thus provides a thorough understanding of the potential benefits of incorporating isooctane into unleaded gasoline, paving the way for future innovations in fuel and engine optimization.

The purpose of this study is to analyze the combustion characteristics of the port fuel injection (PFI) engine considering the fuel mixing ratio, bore to stroke (B/S) ratio and gaseous and particle emissions. Experiments were conducted in a small single-cylinder PFI engine with a displacement of 125 cc. The fuel used in the experiment was a mixture of pure gasoline and ethanol. The engine was operated at 5000 rpm at full load and wide-open throttle. In addition, combustion and exhaust characteristics of the engines with a B/S ratio of 0.88 and 1.15 were analyzed. The combustion pressure inside the combustion chamber was measured to analyze the indicated mean effective pressure (IMEP) and the heat release rate, and the combustion rate was calculated. In the results of combustion characteristics by the difference of B/S ratio, the influence of flame propagation velocity and turbulence intensity is the largest. The 0.88 B/S ratio engine, which has a small bore, has a faster combustion rate than the 1.15 B/S ratio engine due to its larger flame surface area and larger turbulence intensity. This represents a higher efficiency combustion result. Finally, the high oxygen content of ethanol has the characteristic of decreasing soot formation and increasing particle oxidation.

The increment in the usage of automobiles is resulting in increased greenhouse gases (GHG) emissions continuously and there is a substantial need to reduce them effectively. The present research work investigates the emission behavior of waste cooking oil biodiesel doped with CuO nanoparticles during testing in Compression Ignition (CI) engines. This investigation is based on the effective emission reduction analysis emitted by diesel fuel during experimentation on CI engines. It suggests a cost effective modification of biodiesel as a fuel prepared from waste cooking oil (WCO) by a novel hydrodynamic cavitation technique which includes the hydrodynamic cavitation reaction mixture composed of 1.28 L of methanol and 10 g KOH and 5 L of preheated WCO at 45 °C in the cavitation reactor for 40 min. These reactants are synthesized utilizing the principle of cavitation and the final manufactured esterified oil is authenticated with ASTM Standard property measurement for suitability check. In the research work, two different investigations are carried out. In the first one, WCO biodiesel-diesel blends of 0, 30, and 100% (B0, B30, B100) ratio are prepared and the emission characteristics have investigated at 1500 rpm constant speed with varying load and indicated mean effective pressure (IMEP). In the second investigation, the emission suitable blend B30 is doped with CuO nanoparticles, keeping other parameters as per the previous setup, the emission characteristics investigated for the second one. For precise results, more experimental trials are needed to achieve this decrease in the emission of harmful gases. Using an amalgamation of L 9 Taguchi and response surface methodology (RSM) the maximum emission control with a minimum number of experimental trials is achieved. The first investigation includes the predefined predictors as A (blend), B (load), and C (IMEP), where blends (0 ≤ A ≤ 100%), load (0 ≤ B ≤ 12 kg), IMEP (3.5 ≤ C ≤ 7.5 bar) are controllable features. Optimization process resulted into a minimum emission of CO, CO 2 , and NOx by appertaining the condemnatory merger of inputs such as blend B0 (Diesel), load 12 kg, and IMEP 3.48 bar in the first investigation, which has resulted into 0.08 ppm CO, 0.6 ppm CO 2 and 30 ppm NOx emission. Taguchi analysis-based second experimental investigation includes the predefined predictors as A (CuO), B (load), and C (IMEP), including nanoparticles CuO in blend B30, and the prognosticated results of optimization are 0.03 ppm CO, 0.3 ppm CO 2 and 21 ppm NOx emission. In current investigation, the percentage reduction is found to be 92.3%, 94.82%, and 96% compared to the emission of diesel in CO, CO 2 and NOx gases, respectively. The coefficient of determination is almost equal to 1, which reveals the chosen optimization technique is very accurate in prediction. The investigation has provided suitable minimum emission characteristics in a cost-effective way. Article highlights The present investigation explores the harmful gases emission reduction analysis of biodiesel by varying the load, IMEP and proportion of CuO nanoparticles on CI engine testing. Modification of fuel with nanotechnology can be a cost-effective option instead of costlier engine modification. Lesser emission is obtained with WCO biodiesel blend B30 by adding nanoparticles CuO in it.

In this study, exhaust gas emissions are predicted using long short-term memory (LSTM) algorithm and minimum engine data, such as intake air temperature, emission gas temperature, and injection timing. Unlike existing modeling analysis methods, deep learning does not require various vehicle specifications and data, and the correlation between the measured data is derived by itself; therefore, it can serve as a virtual emission sensor. As it is difficult to analyze the correlation between the deep learning and test data from actual road cars because of the complex environment, an experimental single-cylinder diesel engine is used in this study. The intake air temperature is varied from 0 °C to 100 °C, and the injection timing is varied for nitrogen oxide measurement. Consequently, nitrogen oxide is successfully predicted with a high correlation R2 of 0.994 using minimal engine data.

A methodology for determining the cyclic variability in spark-ignition (SI) engines has been developed recently, with the use of an in-house computational fluid dynamics (CFD) code. The simulation of a large number of engine cycles is required for the coefficient of variation (COV) of the indicated mean effective pressure (IMEP) to converge, usually more than 50 cycles. This is valid for any CFD methodology applied for this kind of simulation activity. In order to reduce the total computational time, but without reducing the accuracy of the calculations, the methodology is expanded here by simulating just five representative cycles and calculating their main parameters of concern, such as the IMEP, peak pressure, and NO and CO emissions. A regression analysis then follows for producing fitted correlations for each parameter as a function of the key variable that affects cyclic variability as has been identified by the authors so far, namely, the relative location of the local turbulent eddy with the spark plug. The application of these fitted correlations for a large number of engine cycles then leads to a fast estimation of the key parameters. This methodology is applied here for a methane-fueled SI engine, while future activities will examine cyclic variations in SI engines when fueled with different fuels and their mixtures, such as methane/hydrogen blends, and their associated pollutant emissions.