[en] Highlights: • Nelder-Mead optimization and SVR modeling is conducted on a HSDI diesel engine. • RunID 27 is determined as optimum case among 30 run candidates. • Higher amounts of torque and swirl with lower value of combustion noise is obtained for RUNID27 than baseline. • The potent modeling with statistical index of RMSE = 0.02893 is created for objective prediction. • A bigger bowl and bowl center depth with small bowl middle diameter for optimum case is recommended. - Abstract: Optimization process of energy-related devices is gaining an undivided attention of industrial sectors due to cost effectiveness and practicality attributes. Diesel engines are the most efficient in producing power, although there is a great capacity that has not been fully exploited. Therefore the simplex-based optimization is addressed to enhance the indicated torque (IT), combustion noise (CN), and swirl ratio (SR) of the engine at the same time. The optimum solution is reached at RunID 27, which demonstrates 7.7% increase in IT, 0.19% decrease in CN, and 21.98% increase in SR compared to those of baseline mode. In the present study, IT and CN vary inversely, thus the modification in injection schemes and chamber geometry have to be considered without putting a penalty on another. It was indicated that Min. swirl and torque cases have significantly reduced bowl volume, however, the case with the lowest swirl has lower centerline depth. In addition, it is determined that Max. torque and swirl are obtainable with a big bowl segment, although it was observed that a shallow combustion chamber is expected to induce higher torque. The higher torque is associated with more uniformity of mixture (0.8484) and pressure peak (13.98 MPa) that is plausible with a fitted spray injection with chamber walls coordination, reducing the spray-wall impingement.

[en] Highlights: • CeO_2 nanoparticles in 10–30 nm scale were added to pure diesel in 10, 20, 40 ppm. • NOx and HC were decreased and CO was slightly increased with nanoparticle addition. • Nanoparticle additive slightly reduced FC and brake power had no significant changes. • The ANN modeling provided fast convergence simply and with high accuracy. - Abstract: Reduction of exhaust emission and fuel consumption is one of the most important challenges in the engine communities. One of the methods to overcome the issue is improving fuel by modification or reformulation of its composition. To this end, the experiments were conducted such that the power, emissions, and fuel consumption on a CI diesel engine were altered using fuel blend of diesel with nanoparticles. For this purpose, cerium oxide nanoparticles in 10–30 nm scale were used and added to the base fuel blend in rates of 10, 20, and 40 ppm. The results showed a significant reduction in NOx and HC and a slight increase in CO emissions as compared to pure diesel fuel. In addition, a slight decrease was observed in fuel consumption while the brake power exhibited no significant changes for this fuel blend. Three sets of input elements namely, BSFC, nanoparticle addition, and engine speed were considered whereas power, NO_x, HC, and CO emissions are output parameters. The results, however, indicate that 12 neurons of hidden layer, together with application of Levenberg-Marquardt training rule led to the best network performance with the least MSE value of 0.000172. According to the current investigation, the network modeling succeeded in presentation of efficient interconnecting relation between nanoparticle impact in fuel with engine power and pollutant emissions.

[en] Highlights: • Engine geometrical configuration was modified based on bowl radius and displacement. • The best engine performance indices associated with D3 and R1 structures. • Increasing the bowl radius and outward bowl displacement increases ignition delay. • The best configuration for uniform air/fuel mixture, TKE, and temperature is found. - Abstract: The simulation was carried out based on 1.8 L Ford diesel engine and the geometrical modification in structure of piston were considered in terms of bowl movement and the bowl size in four equal increments. Two major conflicting parameters in combustion and engine efficiency were taken into account and visualized in contour plots as the bowl geometry was varied: (1) the air/fuel mixing process demonstrated by Homogeneity Factor and equivalence ratio, (2) combustion initiation and work delivery by heat release rate, pressure curves, and indicated thermal efficiency. A new version of Coherent Flame Model’s sub-model (ECFM-3Z) was adopted during the calculations to shed light into the combustion chemistry and reaction rate in detail. It was found that the bowl displacement toward the cylinder wall, increases the mixture uniformity (higher HF) thus higher pressure and heat release rate peak were obtained with the penalty of combustion delay which substantially reduces the effective in-cylinder pressure. Furthermore, it was demonstrated that smaller bowl size induces better squish and vortex formation in the chamber, although lesser spray penetration and flame quenching owing to the spray-wall impingement reduces ignition delay

[en] Highlights: • NLPQL algorithm with Latin hypercube and multi-objective GA were applied on engine. • NLPQL converge to the best solution at RunID41, MOGA introduces at RunID84. • Deeper, more encircled design gives the lowest NOx, greater radius and deeper bowl the highest IMEP. • The maximum IMEP and minimum ISFC obtained with NLPQL, the lowest NOx with MOGA. - Abstract: This study is concerned with the application of two major kinds of optimization algorithms on the baseline diesel engine in the class of evolutionary and non-evolutionary algorithms. The multi-objective genetic algorithm and non-linear programming by quadratic Lagrangian (NLPQL) method have completely different functions in optimizing and finding the global optimal design. The design variables are injection angle, half spray cone angle, inner distance of the bowl wall, and the bowl radius, while the objectives include NOx emission, spray droplet diameter, indicated mean effective pressure (IMEP), and indicated specific fuel consumption (ISFC). The restrictions were set on the objectives to distinguish between feasible designs and infeasible designs to sort those cases that cannot fulfill the demands of diesel engine designers and emission control measures. It is found that a design with deeper bowl and more encircled shape (higher swirl motion) is more suitable for NO_x emission control, whereas designs with a bigger bowl radius, and closer inner wall distance of the bowl (Di) may lead to higher engine efficiency indices. Moreover, it was revealed that the NLPQL could rapidly search for the best design at Run ID 41 compared to genetic algorithm, which is able to find the global optima at last runs (ID 84). Both techniques introduce almost the same geometrical shape of the combustion chamber with a negligible contrast in the injection system.

[en] Highlights: • Fuel cell engine hybrid vehicle vs. engine-powered and engine-catalyst for emissions. • Thinner GDL causes lower H₂ consumption, water generation, more FC output energy. • Driving range extended from 3.4 km to 11 km, V_max from 17 km/h to 120 km/h in hybrid. • Optimum power calibration leads electric fuel economy rise 0.1033–0.1104 kWh/km. • 47.3% economizing of gasoline fuel, 47.7% NOx and 61.7% CO reduction in hybrid mode. E-transportation is a next generation technology for internal combustion engine phase-out. In present study, three drivetrain cases are designed: internal combustion engine (ICE), engine-fuel cell coupled configuration, and ICE-catalyst modes. First, the ICE-FC configuration is analyzed and compared with the ICE driven powertrain. Then, the emission of ICE-catalyst mode is compared with that of ICE-FC configuration. The proposed driveline parameters have been examined to monitor the emission, fuel economy, and efficiency of the overall hybrid system. The results indicated that in the new European driving cycle (NEDC), the mileage in hybrid mode has been extended from 3.4 km to 11.0 km. The results also show that by shifting from ICE alone to ICE-FC mode, the fuel consumption (gasoline) decreased from 26.24 1/100 km to 5.38 1/100 km. In addition, the NOx, CO, and HC species have been dropped by 47.7%, 61.7%, and 26.7%, respectively. The engine displacement, cell number of FC and GDL thickness are changed in two levels. Accordingly, when the GDL is thinner, the H₂ consumption is marginally lower while the FC energy output increases up to 5400 kJ and the electric fuel economy is promoted by 6.43%.

[en] Highlights: • The water amount and temperature is considered as injected to combustion chamber. • High water injection rate at 27 °C gives highest total exergy and the lowest irreversibility. • Low water injection rate at 27 °C reduces the heat loss exergy and increase of work exergy. • Low water injection increases power and decreases fuel consumption (ISFC) at 1500 rpm. -- Abstract: The water introduction to combustion chamber can leave two-sided effect on diesel engine performance, thus its role on combustion must be delineated. Accordingly, three levels of water amount in 14.21, 21.31, and 28.41 mg/cycle are adopted to be injected from an upper angled nozzle hole, while fixed diesel amount of 31.3 mg/cycle is injected at 3 °CA BTDC from lower angled nozzle. The water temperature is also taken into account in two levels of 27 °C and 60 °C. By high water injection (HWI) at 60 °C, the rate of pressure rise increases by 17.1% compared to the base case (no water injection) due to steam pressure in the cylinder. The results indicate that WI scheme is effective for fuel consumption, NOx, and soot reduction. In terms of exergy balance by input fuel exergy, it is concluded that the more heat loss exergy is transferring to work exergy in low and medium water injection, while the fuel burn exergy increases drastically. Altogether, the case of diesel injection with high water amount at 27 °C water temperature, i.e. “diesel-HWI-27 °C” is recommended from exergetic viewpoint since it represents the highest total exergy (838.31 J) and the lowest irreversibility (132.98 J).

[en] Highlights: • Advance diverged split injection is studied in exergy terms. • Balanced mass distribution, wider included angle and lesser dwell case increases UI. • A correlation is noticed between rate of pressure rise and rate of irreversibility. • There is a direct link between uniformity index and accumulative work exergy. • 9.5% reduction obtained in exhaust thermo-mechanical exergy by optimum injection set. -- Abstract: A Ford 1.8 l high-speed diesel engine (HSDI) is utilized for a thorough investigation of split dual injection with two included-angle nozzles. The system is equipped with variable-geometry turbocharging (VGT) and high-pressure common-rail (HPCR) technologies which lets multi-injections per cycle. The share of fuel between pulses is divided into three portions of 70-30, 80-20, and 90-10 with included angles of 10, 20, and 30 while the dwell time between pulses are 5CA, 10CA, 15CA, and 20CA. The results demonstrate that the optimum option is 70 (5) 30-30deg “split injection with 70-30% of mass share, dwell of 5CA and with 30° of nozzle divergence” with the best homogeneity of mixture (UI = 0.9742) and peak temperature (T_max = 2011.58 K) that yield maximum thermo-mechanical exergy amounting to 439 J. In addition, the highest amount of accumulative irreversibility happens for 90 (10) 10–20 deg. It is found that there is a relation between mixture uniformity and accumulative work/heat exergy, whereas a high rate of pressure rise (RPR) contribute to irreversibility rate or exergy destruction in diesel engine, i.e. RPR (80-20) = 904.67 kPa/deg. More, the results are in agreement with literature reporting that higher in-cylinder temperature (T_max (70 (5) 30-30deg) = 2011.58 K)) can possibly decrease the accumulative irreversibility.

[en] Highlights: • A new trigeneration cycle was studied from a new viewpoint of exergoeconomic and thermodynamic. • Organic Rankine and refrigeration cycles are used for recovery waste heat of cogeneration system. • Application of trigeneration cycles is advantageous in economical and thermodynamic aspects. - Abstract: In this paper, a combined cooling, heating and power cycle is proposed consisting of three sections of gas turbine and heat recovery steam generator cycle, Regenerative organic Rankine cycle, and absorption refrigeration cycle. This trigeneration cycle is subjected to a thorough thermodynamic and exergoeconomic analysis. The principal goal followed in the investigation is to address the thermodynamic and exergoeconomic of a trigeneration cycle from a new prospective such that the economic and thermodynamic viability of incorporating Regenerative organic Rankine cycle, and absorption refrigeration cycle to the gas turbine and heat recovery steam generator cycle is being investigated. Thus, the cost-effectiveness of the introduced method can be studied and further examined. The results indicate that adding Regenerative organic Rankine cycle to gas turbine and heat recovery steam generator cycle leads to 2.5% increase and the addition of absorption refrigeration cycle to the gas turbine and heat recovery steam generator/ Regenerative Organic Rankine cycle would cause 0.75% increase in the exergetic efficiency of the entire cycle. Furthermore, from total investment cost of the trigeneration cycle, only 5.5% and 0.45% results from Regenerative organic Rankine cycle and absorption refrigeration cycles, respectively.

[en] Highlights: • Effect of in-cylinder combustion parameters on soot and NOx emissions at rated EGR levels was studied. • ANN model was adopted to predict the emissions under the effect of combustion parameters. • A trainlm ANN with 5-19-17-2 structure denoted MSE equal to 0.0004627 as outperforming model. • Increment of EGR reduced the emissions where the equivalence ratio had contradictory effect. - Abstract: This study examines the effect of in-cylinder combustion parameters on soot and NOx emissions at rated EGR levels by using the data obtained from the CFD implemented code. The obtained data were subsequently used to construct an artificial neural network (ANN) model to predict the soot and NOx productions. To this aim, at three different engine speeds of 2000, 3000 and 4000 rpm, heat release rate, equivalence ratio, turbulence kinetic energy and temperature varied to obtain the relevant soot and NOx data at three EGR levels of 0.2, 0.3 and 0.4. It was discovered that wherein the application of higher EGR rates reduced the NOx as a result of mixture dilution, equivalence ratio increment makes soot production to be increased as well as NOx emission. It was also found that the application of higher EGR from 20% to 40% decreased soot mass fraction in the combustion chamber. Increment of EGR reduced the emissions where the equivalence ratio had contradictory effect on the produced emissions. Various ANN topological configurations and training algorithms were incorporated to yield the optimal solution to the modeling problem applying statistical criteria. Among the four adopted training algorithms of trainlm, trainscg, trainrp, and traingdx, the training function of Levenberg–Marquardt (trainlm) with topological structure of 5-19-17-2 denoted MSE equal to 0.0004627

[en] Highlights: • A three component fuel combustion of diesel-DME-methanol investigation in HCCI engine. • The feasibility of DME and methanol replacement with diesel is evaluated in advanced exergetic framework. • The effect of 20% EGR on rate of pressure rise and ignition delay of blended fuel is considered. • D50 fuel exceeds in mechanical efficiency, D60 in exergy performance coefficient and lower irreversibility. • D80 shows minimum work exergy and maximum irreversibility. -- Abstract: A homogeneous compression ignition (HCCI) engine is taken for numerical investigation on the application of renewable fuels contained blends of methanol and DME with the base diesel fuel, which will be replaced with diesel in different percentages. First, the combustion and engine performance of the engine for two and three-component fuels will be discussed and secondly, the simultaneous effect of EGR in 20% by mass and engine speed in two blends of having maximum and minimum diesel proportion are compared and examined. The results indicate that the replacement of diesel with 20% of DME and 30% by methanol (D50M30DME20) at 1400 rpm generates a greater pressure and accumulated heat (AHR_peak = 330.569 J), whereas D80M20/2000 rpm/EGR20 gives a defective combustive performance with poor engine efficiency (IMEP = 7.21 bar). The interesting point is that the proposed optimum blend of D50 can achieve the best performance with 35% mechanical efficiency of 35%. The case of D60M10DME30 though dominates in terms of RPR = 3.177 bar/deg and ignition delay (ID = 4.54 CA) that gives the highest exergy performance coefficient (EPC = 2.063) due to its high work and lowest irreversibility.