Kinetic modeling of ion formation during diesel combustion with different fuel injection timing

Ions are formed during the combustion process in internal combustion engines. The measurement of ions inside the combustion chamber produces reliable information about the combustion process. The present study focuses on the formation of ions inside the combustion chamber of diesel engines with different injection timing. For this purpose, a multi-zone thermodynamic model is utilized to simulate the closed cycle of the engine. To understand the kinetic behavior of the ions, the model is connected to an ionic chemical kinetics mechanism with 336 reactions and 81 species. Six important ionic reactions comprising 5 ions are used in the ionic mechanism. Dvode differential equation solver is also employed to calculate the energy and kinetics equations. The developed model has an acceptable accuracy in predicting the performance and pollutants of diesel engines. Based on the results, the ion formation is delayed by delaying the fuel injection timing. The maximum amount of in-cylinder ions depends on injection timing. In-cylinder ion current can predict the start of combustion accurately.

Energizing tomorrow: unleashing spirulina's potential in engine performance optimization and emission reduction

Dwindling of fossil fuels and the global climate change has prompted civilization to look into alternate energy sources. This has led to explore inexhaustible and sustainable resources in the domain of renewable energy. Among all sources renewable energy, biofuel produced from biomass has great prospect for energy security as well as environmental safety over fossil fuels. The present work tries to explore the performance attributes and emission characteristics of a CI engine utilizing spirulina microalgae biodiesel blend comprising of 20% algae biodiesel blended with 80% diesel. This blend is tested in a diesel engine at varying engine load conditions of 20%, 40%, 60%, 80%, and 100% at variable injection timing of 20°, 23°, 25°, and 28° bTDC, respectively at compression ratio of 18. Based on experimental results, the peak brake thermal efficiency for injection timing of 20°, 23°, 25°, and 28° bTDC at 100% engine load were observed to be 26.79%, 23.77%, 24.77%, and 25.09%, respectively for the biodiesel blend in comparison to 27.76% of diesel mode whereas the emissions levels were found to minimum at 20° bTDC. On the part of emission, the average drop in CO emissions for injection timing of 20°, 23°, 25°, and 28° bTDC were found to be 53.46%, 43.71%, 44.34%, and 50.31%, respectively for biodiesel blend as compared to diesel mode. For the same setting, in comparison diesel mode, the average fall in HC emissions were found to be 42.32%, 34.13%, 30.37%, and 37.54%, respectively, and the rise of NOx emissions were found to be 8.06%, 5.55%, 3.51%, and 3.04%, respectively. Response surface methodology was applied for optimization of operating parameters of the algae biodiesel blend run diesel engine. The desirability based study revealed that at 85.19% engine load and injection timing of 20° bTDC were optimal operation settings which resulted in engine performance of 25.44% brake thermal efficiency. The emission level at this setting was observed to be reduced to 27.68 ppm CO, 1.60% CO2, 24.65 ppm HC, and 182.15 ppm NOx.

Effects of klotho protein or klotho knockdown in porcine oocytes at different stages

Klotho is a protein that plays different functions in female fertility. We have previously reported that klotho protein supplementation during in vitro maturation improves porcine embryo development, while klotho knockout for somatic cell cloning completely blocks full-term pregnancy in vivo. However, the effects of the microinjection of klotho protein or klotho knockdown dual vector in porcine embryos at different time points and the specific molecular mechanisms remain largely unknown. In this study, we injected the preassembled cas9 + sgRNA dual vector, for klotho knockdown, into the cytoplasm of the germinal vesicle stage of oocytes and into porcine embryos after 6-h parthenogenetic activation. Similarly, the klotho protein was inserted into the cytoplasm of germinal vesicle stage oocytes and porcine embryos after 6-h parthenogenetic activation. Compared with the controls, the microinjection of klotho dual vector markedly decreased the blastocyst formation rates in germinal vesicle stage oocytes and activated embryos. However, the efficiency of blastocyst formation when klotho protein was inserted before in vitro maturation was significantly higher than that after klotho protein insertion into parthenogenetically activated embryos. These results indicated that klotho knockdown may impair embryo development into blastocyst irrespective of injection timing. In addition, klotho protein injection timing in pig embryos may be an important factor for regulating embryo development.

Experimental analysis on the influence of compression ratio, flow rate, injection pressure, and injection timing on the acetylene - diesel aspirated dual fuel engine

The predicted scarcity, increasing cost of petroleum fuels, and environmental degradation are encouraging researchers to search for alternative fuels throughout the world. Hence, it is intended to utilize acetylene-based DF in the compression ignition (CI) engine with minor modifications. An engine of 5 Hp, four stroke, single-cylinder, water-cooled operated in dual-fuel (DF) mode (acetylene gas-diesel), aiming to reduce the emissions, was deployed to investigate its characteristics. In DF mode, gaseous fuel is injected through intake air manifold with 2, 4, and 6 lpm constantly. According to the research findings, the gas rate of 6 lpm provides the best results, having a superior BTE of 30.7%. Various compression ratios (16:1, 18:1, and 20:1) were used to determine the optimal compression ratio (CR) under a volume flow rate of 6 lpm with diesel. Fuel injector pressure (200, 220, and 240 bar) with injector intervals (19°, 23°, and 27°bTDC) were changed consecutive sequence while adjusting CR, and the best outcomes for improved CI fuel efficiency were determined. From the investigational analysis, the peak in-cylinder pressure and net HRR (heat release rate) are assessed for being better by the increment in CR in DF mode of operation with an acetylene gas of 6 lpm at all operating settings. At a 240 bar injection pressure, the BTE is recorded highest (35.1%), and smoke was decreased. An IT of 23obTDC, the CO and HC were found as to be minimum as 28 ppm and 0.04 ppm.

Effect of injection timing on knock combustion and pollutant emission of heavy-duty diesel engines at low temperatures

The knock combustion and pollutant emission of heavy-duty diesel engines at low temperatures are still unclear, especially under different injection timings. Therefore, this study illustrates the above issues through CONVERGE simulation. The results show that with the start of injection (SOI) sweeps from -7°CA to -32°CA, a large amount of liquid-phase fuel adheres to the wall, and the wet-wall ratio of fuel at SOI = -32°CA is as high as nearly 30%. The fuel film evaporates slowly, coupled with the effect of low temperature on chemical reactions, the high-temperature ignition (HTI) is delayed seriously until the end of injection. The amount of premixed mixture formed during long ignition delay is significantly increased, but its uniformity is better and the concentration is more suitable for ignition. Once HTI is triggered, high-frequency and strong pressure oscillation occurs in the cylinder, and the maximum oscillation amplitude is as high as nearly 10 MPa, far exceeding the threshold of destructive knock combustion. Delayed fuel injection can effectively alleviate the above problems, such as the best when the SOI in this study is -17°CA. In addition, HC emissions are positively correlated with the amount of fuel film, but the trend of CO quantity with injection timing shows the opposite result. NO_x emission increases as the injection timing advances, while soot is the opposite, because the mixture concentration is leaner at the earlier SOI and the expanded high-temperature region leads to an accelerated oxidation rate of soot.

Exploring the efficiency and pollutant emission of a dual fuel CI engine using biodiesel and producer gas: An optimization approach using response surface methodology

The present study focuses on optimizing the engine operating parameters of a dual-fuel (DF) engine. Producer gas (PG) and Honge oil methyl ester (HOME) are used as primary fuel and pilot fuel respectively for the operation. An experimental design matrix of 20 different combinations was considered using Design of Experiments (DoE), based on the central composite design (CCD) of response surface methodology (RSM). The effects of these combinations were experimentally investigated to calculate the performance and emission characteristics of the engine. The objective of the work is to maximize the Brake thermal efficiency (BTE) and minimize the exhaust gas temperature (EGT), nitrogen oxide (NOx), hydrocarbon (HC), and carbon monoxide (CO) emissions. The RSM model is developed using the experimental data and further, the operating parameters were optimized using the desirability approach. The optimized combination of operating parameters was obtained at 61.10% engine load, compression ratio (CR) of 18, and injection timing (IT) of 23.30° before top dead center (BTDC). The optimum responses corresponding to these operating conditions were found as 14.23%, 354.29 °C, 52.18 ppm, 39.53 ppm, and 0.51% for BTE, EGT, NOx, HC, and CO respectively with an overall desirability of 0.962. The optimized responses were validated experimentally at optimum input conditions and found to be within acceptable error levels. Further, an economic analysis of the optimized DF system is also carried out.

Soft computing-based modeling and emission control/reduction of a diesel engine fueled with carbon nanoparticle-dosed water/diesel ‎emulsion fuel

This study was set up to model and optimize the performance and emission characteristics of a diesel engine fueled with carbon nanoparticle-dosed water/‎diesel emulsion fuel using a combination of soft computing techniques. Adaptive neuro-fuzzy inference system tuned by particle ‎swarm algorithm was used for modeling the performance and emission parameters of the engine, while optimization of the engine operating parameters and the fuel composition was conducted via multiple-objective particle ‎swarm algorithm. The model input variables were: injection timing (35-41° CA BTDC), engine load (0-100%), nanoparticle dosage (0-150 μM), and water content (0-3 wt%). The model output variables included: brake specific fuel consumption, brake thermal efficiency, as well as carbon monoxide, carbon dioxide, nitrogen oxides, and unburned hydrocarbons emission concentrations. The training and testing of the modeling system were performed on the basis of 60 data patterns obtained from the experimental trials. The effects of input variables on the performance and emission characteristics of the engine were thoroughly analyzed and comprehensively discussed as well. According to the experimental results, injection timing and engine load could significantly affect all the investigated performance and emission parameters. Water and nanoparticle addition to diesel could markedly affect some performance and emission parameters. The modeling system could predict the output parameters with an R² > 0.93, MSE < 5.70 × 10^-3, RMSE < 7.55 × 10^-2, and MAPE < 3.86 × 10^-2. The optimum conditions were: injection timing of 39° CA BTDC, engine load of 74%, nanoparticle dosage of 112 μM, and water content of 2.49 wt%. The carbon dioxide, carbon monoxide, nitrogen oxides, and unburned hydrocarbon emission concentrations ‎were found to be ‎7.26‎ vol%‎, ‎0.46 vol%‎, ‎95.7‎ ppm, and‎ 36.2 ppm, respectively, under the ‎selected optimal operating conditions while the quantity of brake thermal efficiency was found at an acceptable level (‎34.0‎%).‎ In general, the applied soft computing combination appears to be a promising approach to model and optimize operating parameters and fuel composition of diesel engines.

Preoperative lumbar epidural steroid injections administered within 6 weeks of microdiscectomy are associated with increased rates of reoperation

PURPOSE

Lumbar epidural steroid injections (LESIs) are widely utilized for back pain. However, as studies report adverse effects from these injections, defining a safe interval for their use preoperatively is necessary. We investigated the effects of preoperative LESI timing on the rates of recurrent microdiscectomy.

METHODS

This study utilized the PearlDiver national insurance claims database. Microdiscectomy patients were stratified by the timing of their most recent LESI prior to surgery into bimonthly cohorts (0-2 months, 2-4 months, 4-6 months). This first cohort was further stratified into biweekly cohorts (0-2 weeks, 2-4 weeks, 4-6 weeks, 6-8 weeks). The 6-month reoperation rate was assessed and compared between each injection cohort and a control group of patients with no injections within 6 months before surgery. Univariate analyses of reoperation were conducted followed by multivariate analyses controlling for risk factors where appropriate.

RESULTS

A total of 12,786 microdiscectomy patients were identified; 1090 (8.52%) received injections within 6 months before surgery. We observed a significant increase in the 6-month reoperation rates in patients who received injections within 6 weeks prior to surgery (odds ratio [OR] 1.900, 1.218-2.963; p = 0.005) compared to control. No other significant differences were observed.

DISCUSSION

In this study, microdiscectomy performed within 6 weeks following LESIs was associated with a higher risk of reoperation, while microdiscectomy performed more than 6 weeks from the most recent LESI demonstrated no such association with increased risk. Further research into the interaction between LESIs and recurrent disk herniation is necessary.

Simulation data for similarity of spray combustion processes in marine low-speed diesel engines

Scaled model experiments are very useful for reducing time, cost and energy consumption in marine diesel engine development. This data article is based on the research work which examines the potential of scaled model experiments for marine low-speed diesel engines. Two engines of 340 and 520 mm bore diameters are employed to conduct this numerical scaling work based on three diesel combustion scaling laws. Data on similarity of peak swirl ratio, heat transfer losses, liquid and vapor penetration length, ignition delay, in-cylinder peak temperature, peak carbon monoxide (CO), peak hydrocarbon (HC) and carbon dioxide (CO2) emissions for various fuel injection timing are provided. The data in this paper are valuable reference for researchers or engineers who attempt to conduct scaled model experiments in marine diesel engine development.

Influence of injection timing and exhaust gas recirculation (EGR) rate on lemon peel oil-fuelled CI engine

In the current phase of world economy, the utilization of the petroleum-based fossil fuels has drastically surpassed the supply. This scenario supplements to the fact that there is an ever increasing necessity for industrialization, specifically in the transportation sector. This requirement and supply of the petroleum and diesel fuels have an astounding impact over the market economy and related commodities. Low viscous and low cetane number biofuels are getting more attention for their usage in engine applications without any further processing. In the present work, lemon peel oil is being fuelled in diesel engine at different timing of injection and exhaust gas recirculation rates. Operation of lemon peel oil (LPO) at standard operating conditions results in increased brake thermal efficiency by consuming less fuel when compared with diesel fuel. The LPO biofuel properties such as boiling point and viscosity being lower leads to better evaporation capacity and thereby results in complete combustion. The advancement in injection timing of 25° bTDC and 27° bTDC resulted in the efficiency increment of 2.17% and 6.19% respectively. Furthermore, the smoke, carbon monoxide and hydrocarbon emissions are decreased in consequence on increased nitrogen oxide (NOx) emissions. Hence, in order to decrease the content of nitrogen oxide emissions in the exhaust, exhaust gas recirculation (EGR) has been implemented in the present work. For EGR rate of 10% and 20%, the NOx emissions is reduced by 43% and 46% respectively for 27° bTDC injection timing. Thus, the advancement of injection timing with optimum EGR is a viable option for the lemon peel oil biofuel in diesel engine with superior performance and emission output.

Engine parameter optimization of palm oil biodiesel as alternate fuel in CI engine

Stringent emission regulations and depletion of crude oil are driving researchers toward alternative fuels. In this context, palm oil emerges as a good competitor as it is highly economical compared to other alternative fuels. The current research work centers around the impact of palm oil methyl ester on performance, combustion, and emission characteristics at varying injection timings and exhaust gas recirculation rates. In the first phase of this research work, various blends of palm oil methyl ester with diesel with volume concentrations of 10, 20, and 30% were prepared and tested at different load conditions. Injection timing was then varied for the optimized blend. In the second phase, the impact of exhaust gas blending with fresh charge was studied at optimized injection timing. The test outcomes revealed that 20% mix of palm oil at 27° bTDC with exhaust gas blending of 20% generated higher brake thermal efficiency, higher peak pressure, and less hydrocarbon and nitrogen oxide emissions compared to diesel at standard injection timing of 23° bTDC and no blending of exhaust gases with fresh charge. However, progression of injection timing with 20% exhaust gas mixing indicated a slight penalty in smoke discharges. Brake thermal efficiency at advanced injection timing with 20% mix of exhaust gases reduced by 7.7% for diesel and increased by 6.5% for 20% blend of palm oil when compared to standard injection timing of diesel and no blending of exhaust gases. Significant diminishments in oxides of nitrogen (lessened by 6.6%) and hydrocarbons (decreased by 30.43%) have been noted for 20% mix of biodiesel at advanced injection timing with 20% exhaust gas mix contrasted to diesel at standard conditions. Therefore, the present examination prescribes 20% merging of exhaust gases for 20% blend of palm oil with advancement of injection timing for diesel engine applications.