•A blend of recycled fuel and renewable fuel was utilized in diesel engine.•Collective influence of 1-decanol, fuel injection pressure and EGR on engine characteristics were studied.•Best operating ...parameters were determined.
Plastic waste is abundant and its recovery to diesel-like fuel could reduce fossil fuel dependency and the associated risk of environmental pollution. In the present work, diesel-like fuel was produced from low-density polyethylene by catalytic pyrolysis method. Experiments were conducted to study the effect of substituting 10% vol. of 1-decanol in place of waste LDPE oil in D70L30 blend, under the influence of three injection pressures (400 bar, 500 bar, and 600 bar) and three EGR rates (0%, 10%, and 20%) on performance, combustion and emission characteristics of a CRDi engine at its rated power output. For this purpose, a ternary blend was prepared and the results were compared with diesel and D70L30 blend. Results reveal that, the substitution of 1-decanol in place of waste LDPE oil resulted in the shorter ignition delay period. The peak in-cylinder pressure and peak HRR dropped with increasing EGR rate and decreasing injection pressure. D70L20DEC10 injected at 600 bar with 0% and 10% EGR rates delivered 1.02% and 0.5% better BTE than D70L30 blend. NOx decreased by 112% when the EGR was increased from 0% to 20% at 400 bar FIP. It is concluded that the 1-decanol blend injected at 600 bar pressure and a low EGR rate of 10% gave the best possible performance and low emissions.
Biofuels have grabbed the attention of engine researchers ever since the oil-crisis and escalating costs of petro-chemicals cropped up in the ׳70s. Ethanol and methanol were the most widely ...researched alcohols in IC engines. However, the last decade has witnessed significant amount of research in higher alcohols due to the development of modern fermentation processes using engineered micro-organisms that improved yield. Higher alcohols are attractive second/third generation biofuels that can be produced from sugary, starchy and ligno-cellulosic biomass feedstocks using sustainable pathways. The present work reviews the current literature concerning the effects of using higher alcohols ranging from 3-carbon propanol to 20-carbon phytol on combustion, performance and emission characteristics of a wide range of diesel engines under various test conditions. The literature is abound with evidence that higher alcohols reduce carcinogenic particulate emissions that are prevalent in diesel engines. NOx emissions either increased or decreased based on the domination of either cetane number or heat of evaporation. Brake specific fuel consumption (BSFC) of the engine usually suffered due to low energy content of alcohols. A notable feature is that the combination of higher alcohols (like butanol or pentanol), high exhaust gas recirculation (EGR) rates and late injection timing enabled low temperature combustion (LTC) in diesel engines that can simultaneously reduce smoke and NOx emissions with improved engine efficiency. It can be concluded that higher alcohols reduce smoke emissions with their fuel-borne oxygen; enhance air/fuel mixing by offering long ignition delay and eventually replace fossil diesel (partially or wholly) to enable a clean and efficient combustion in compression-ignition engines. The chief thrust areas include developing mutant strains with higher yield, higher tolerance to toxic inhibition and low-cost substrates for fermentation. Further work is required in stipulating optimum blend-fuel characteristics and ensuring the long-term durability of the engines using these fuels.
Using a three-step aqueous solution ion-exchange method, cocation modified Cu/SSZ-13 SCR catalysts were synthesized. These catalysts, in both fresh and hydrothermally aged forms, were characterized ...with several methods including temperature-programmed reduction by H2 (H2-TPR), temperature-programmed desorption of NH3 (NH3-TPD), and 27Al solid-state nuclear magnetic resonance (NMR) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopies. Their catalytic performance was probed using steady-state standard NH3–SCR. Characterization results indicate that cocations weaken interactions between Cu ions and the CHA framework making them more readily reducible. By removing a portion of Brønsted acid sites, cocations also help to mitigate hydrolysis of the zeolite catalysts during hydrothermal aging as evidenced from 27Al NMR. Reaction tests show that certain cocations, especially Li+ and Na+, promote low-temperature SCR rates while others show much less pronounced effects. In terms of applications, our results indicate that introducing cocations can be a viable strategy to improve both low- and high-temperature performance of Cu/SSZ-13 SCR catalysts.
•Effects of %NH3 and SODI on ADDF engine were investigated at medium load conditions.•Increasing %NH3 increased the N2O and GHG emissions of ADDF engine.•Using advanced SODI reduced GHG emissions of ...ADDF engine by 12% compared to diesel mode.•NOx and CO emissions of ADDF engine were 10% and 20% lower than diesel engine.
Ammonia has been receiving increasing interest as a hydrogen carrier and carbon-free fuel to tackle the issue of greenhouse gas (GHG) emissions from transportation. In this study, an ammonia/diesel dual-fuel (ADDF) engine is experimentally and numerically investigated, with focus on its feasibility to reduce GHG emissions while achieving a diesel-like efficiency. A single-cylinder, heavy-duty diesel engine is used to investigate the effect of ammonia energy fraction and start of diesel injection (SODI) timing on the combustion performance and emissions of the ADDF engine. Results revealed that due to the low flame speed of ammonia, increasing the ammonia energy fraction decreased the thermal efficiency of the ADDF combustion mode compared to the diesel-only combustion mode. Increasing ammonia energy fraction from 0 to 40% reduced the nitrogen oxides (NOx) emissions by 58.8% at a given SODI due to the effect of the thermal DeNOx process. However, increasing the ammonia energy fraction at a given SODI increased the nitrous oxide (N2O) emissions, which offsets the benefit of lower intrinsic carbon dioxide (CO2) emissions of ADDF combustion and resulted in a higher GHG emission compared to diesel-only combustion. Advancing SODI helped reduce the N2O and overall GHG emissions while achieving a diesel-like thermal efficiency in ADDF combustion mode. The lowest GHG emissions of ADDF combustion achieved by advancing the SODI were 12% lower compared to those of diesel-only combustion. The thermal efficiency of ADDF combustion mode at the optimum point of GHG emissions (i.e., ITE = 37.85%) was slightly lower than that of the diesel-only combustion mode (i.e., ITE = 38.53%). This, however, comes with a benefit of 10% and 20% reduction in NOx and CO emissions, respectively. The unburned ammonia concentration is high (i.e., about 4445 ppm) in the exhaust flow. The reduction of ammonia emissions in the exhaust flow should be further investigated in the future.
•A transient quasi-steady jet theory is proposed and a more accurate effective injection velocity is derived.•Time dependence characteristics of spray tip penetration in multiple injection is ...investigated.•A flexible diesel spray model was developed theoretically for advanced injection strategy.
Diesel engine has witnessed an increasingly stringent emission regulation due to its concomitant serious environmental pollution problems. Various advanced injection strategies have been proposed to cope with the emissions issues of diesel engine, but also increase the difficulty for evaluating spray tip penetration (Stip). Meanwhile the time dependence characteristics of Stip in multiple-injection is still unknown so far. Gaining a thorough understanding of Stip is extremely important to assess the spray mixing process and further adjust injection and combustion strategy to maximize the efficiency of diesel engines. Therefore, this paper aims to develop a flexible spray model for the quick and robust prediction of Stip under various advanced injection strategies and study the time dependence characteristics of Stip in multiple-injection. First a reduced analytical expression of effective injection velocity is derived based on the assumption of transient quasi-steady jet. Then a variable Stokes number (St) depending upon the change of injection velocity is formulated. Next a single injection spray model is developed by embedding the effective injection velocity in an existing analytical spray model. Meanwhile, the multiple-injection spray model is established with a penetrating enhancement coefficient (EC) introduced to correct its time dependence characteristics of Stip. Finally, the newly developed Stip models are validated experimentally under varied injection strategies. The results show that the newly developed Stip models could flexibly apply to various advanced injection strategies, and for the multiple-injection strategy, the first injection quantity and the dwell time are two major impact factors to the second injection.
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•JP-5 blended with seven alcohols between 10% and 30 vol%•Most mixture flash points below & densities within military diesel specification.•Longer engine ignition delays with higher ...alcohol content & smaller alcohols.•Higher heat release rates with higher alcohol content & smaller alcohols.•Increasing combustion phasing delays with more and smaller alcohols.
Military operations may involve the use of jet fuel in a diesel engine, and the blending of alcohols with jet fuel is a way to introduce decarbonization into military operations. This study explored the effect of blending n-alcohols with navy jet fuel JP-5 on physical properties and combustion in a diesel engine. Blends containing 10 %, 20 %, and 30 % of ethanol, propanol, butanol, pentanol, hexanol, octanol, and one mixture of 10 % methanol/80 % octanol had densities (0.80 to 0.81 g/mL) that fell within military specifications for diesel. Most mixtures' flash points (16.5 to 65.0 °C) were below the military spec of 60 °C, which is higher than that of commercial aviation fuel. Most mixture viscosities (4.74 to 9.99 mm2/s) were within the jet fuel specifications at −20 °C but below the diesel fuel specification at 40 °C. Combustion of the alcohol/JP-5 mixtures in a diesel engine showed that increasing alcohol content lengthened the ignition delay (IGD). For some of the alcohols, shortening the carbon chain length on the alcohol led to longer IGDs with later combustion phasing that was most noticeable at lighter engine loads. The longer IGDs associated with the shorter alcohol fuels (and increased alcohol percentage) rapidly led to very high rates of energy release. The relative IGDs (IGD mixture/IGD JP-5) were less than 1.2 for the 10 % alcohol mixtures, between 1.0 and 1.4 for the 20 % alcohol mixtures, and between 1.0 and 1.9 for the 30 % alcohol mixtures excluding the 30 % ethanol mixture that did not combust. From the combustion metrics perspective, the longer carbon chain alcohols were most similar to the base jet fuel. Overall, the larger alcohols had physical properties and combustion metrics that were closer to those of the JP-5 jet fuel.
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•DEE was examined as an oxygenated fuel additive in various ratios in a CI engine.•Comparing performance, emissions and combustion attributes among all blends.•DEE in the ...biodiesel-diesel blend adversely affected the engine performance.•DEE in the ternary blends led to improve the exhaust emission characteristics.•Ternary blends exhibited almost similar combustion behaviors compared to the diesel.
The objective of the present study refers to the examination of a diesel engine characteristics for various fractions of diethyl ether (DEE) as an oxygenated fuel additive in cottonseed oil biodiesel-diesel fuel blends. Firstly, several tests performed for diesel and B20 blend. Then, 2.5%, 5%, 7.5%, and 10% of DEE by volume was mixed with biodiesel-diesel fuel to prepare the ternary blends. All the fuel samples were run on in a single-cylinder, four-stroke, and direct-injection diesel engine at five different engine loads and fixed engine speed conditions. The experimental results showed that BTE was decreased by 17.39% while increasing in BSFC by 29.15% for 10% addition of DEE in the blend as compared to diesel fuel. Besides, the engine fueled with ternary blends revealed mitigation up to 12.89%, 4.12%, and 8.84% in the HC, smoke, and NOX emissions, on an average, respectively than those of diesel fuel. CO emission exhibited increasing trends with the diesel fuel at higher proportions of DEE despite up to 40.09% dropdown remarked for lower concentration at the maximum load. By the way, the CO2 also dropped under high loads. However, the combustion behaviors vaguely deteriorated when the CI engine run on all ternary blends. As a consequence, DEE can be evaluated as an auspicious aspect to remove the main issues with the usage of cottonseed oil biodiesel. It can be further highlighted that the addition of DEE up to 10% (by vol.) could be considered as a promising techniquefor the utilization of biodiesel/diesel blend efficiently in the CI engines without any major modifications.
•Engine load, palm oil ratio and injection advance have been chosen as input parameters.•Proposed RSM and ANN model are capable for mapping engine performance-emission paradigms with high ...accuracy.•RSM was applied to optimize the engine performance and exhaust emissions.•Trade-off study based on RSM technique showed the optimal engine operating condition for biodiesel/diesel blends.
Engine performance and emission characteristics of palm oil-diesel blends tested on single-cylinder diesel engine by several engine loads and injection advances. Exhaust emissions and smoke were recorded using MRU Delta 1600L and MRU Optrans 1600 model gas analyzer, respectively. Brake thermal efficiency (BTE), exhaust gas temperature (EGT), carbon monoxide (CO), hydrocarbon (HC), smoke and nitrogen oxides (NOx) were optimized as output factors considering engine load, injection advance and palm oil percentage as input variables using response surface methodology (RSM) and artificial neural network (ANN). The developed ANN and RSM models showed superior predictive certainty with big R2 (correlation coefficient) values. The RSM models showed better performance and have higher R2 values than ANN models. The developed RSM model has R2 values over 0.90 while the R2 values of ANN model are between 0.88 and 0.95. The values of mean relative error (MRE) and root mean square error (RMSE) for all the responses were low. Optimum responses were found by 69.11%, 196.25 ppm, 0.126%, 189.764 ppm, 155.49 ℃ and 30.75%, respectively for smoke, NOx, CO, HC, EGT and BTE with optimum operating factors as 17.88% palm oil percentage, 35 °CA injection advance and 780-watt engine load. The applied models gave good results that are beneficial for estimating and optimizing the engine performance and emission characteristics.
The oil obtained by pyrolysis of waste plastics can be used as an alternate fuel for diesel engine without making any modification to the engine. The WPPO (waste plastic pyrolysis oil) mixed with 5% ...and 10% DEE (diethyl ether) were used as fuels for single cylinder water cooled, DI engine and its performance, emission and combustion characteristics were found. The experimental results indicated the reduction in smoke levels with that of baseline waste plastic pyrolysis oil. The BTE (brake thermal efficiency) increased when compared to pure plastic pyrolysis oil and diesel. The pollutants such as CO (carbon monoxide) and NOx (nitrous oxide) were reduced in the blend. It was observed that addition of oxygenates had improved the combustion process and reduced the emissions. The investigation revealed that blending of DEE with plastic oil increases the Cetane rating which is superior to neat diesel.
•Diethyl ether blended in different proportions with waste plastic oil used as fuel in diesel engine.•The addition of diethyl ether with waste plastic oil improves brake thermal efficiency.•Addition of diethyl ether increases the unburned hydrocarbon emission.•The NOx decreases with increase in percentage of diethyl ether.•Addition of diethyl ether shortens the ignition delay.
Escalating fuel prices and imposition of carbon dioxide emission limits are creating renewed interest in methods to increase the thermal efficiency of marine diesel engines. One viable means to ...achieve such improved thermal efficiency is the conversion of engine waste heat to a more useful form of energy, either mechanical or electrical. Organic Rankine Cycle (ORC) has been demonstrated to be a promising technology to recover waste heat. This paper examines waste heat recovery of a marine diesel engine using ORC technology. Two separated ORC apparatuses for the waste heat from both the jacket cooling water and the engine exhaust gas are designed as the traditional recovery system. The maximum net power output is chosen as the evaluation criterion to select the suitable working fluid and define the optimal system parameters. To simplify the waste heat recovery, an optimized system using the jacket cooling water as the preheating medium and the engine exhaust gas for evaporation is presented. The influence of preheating temperature on the system performance is evaluated to define the optimal operating condition. Economic and off-design analysis of the optimized system is conducted. The simulation results reveal that the optimized system is technically feasible and economically attractive.
•ORC is used to recover waste heat from both exhaust gas and jacket cooling water.•Comparative study is conducted for different ORC systems.•Thermal performance, system structure and economic feasibility are considered.•Optimal preheating temperature of the system is selected.
