Multi-objective optimization of the engine performance and emissions for a hydrogen/gasoline dual-fuel engine equipped with the port water injection system

Hydrogen is one of the most promising options being considered as the fuel of future. However, injection of hydrogen into modern gasoline fueled engines can cause some issues such as power loss. This study, therefore, aims to address this challenge in a simulated hydrogen/gasoline dual-fueled engine by developing a novel and innovative approach without possible side effects such as NOx increment. To achieve this goal, the impacts of water injection and the start of the combustion (SOC) modification in a gasoline/hydrogen duel fueled engine have been rigorously investigated. In current methodology, an engine is simulated using AVL BOOST software and the model is validated against the experimental data. The Latin Hypercube design of experiments method was employed to determine the design points in 3-dimensional space. Due to the existing trade-off between NOx and BMEP, multi-objective optimization using genetic algorithm (GA) was implemented to determine the optimum values of water injection and SOC in various hydrogen energy shares and the effects of optimum design parameters on the main engine performance and emission parameters were investigated. The results showed that the proposed solution could recover the brake mean effective pressure (BMEP) and in some hydrogen energy shares even increase it above the level of single fueled gasoline engine with the added benefit of there being no increase in NOx compared to the original level. Furthermore, other emissions and engine performance parameters are improved including the engine equivalent Brake specific fuel consumption (BSFC) which was shown to increased up to 4.61%.     

Performance and exhaust emission characteristics of a CI engine fueled with diesel-nitrogenated additives

In present work the effects of nitromethane (NM) and nitroethane (NE) as nitrogenated additives on physical properties, combustion performance, and emission of diesel fuel, were studied. Nitrogenated additives have high oxygen content and are considered as oxygenated additives. These additives were blended with diesel fuel, in 1/9 volume ratio. The experimental study was carried out on ECE R-96 8-modes cycle. The result showed that the use of additives reduces viscosity but increases cetane index. In addition, nitrogenated additives increased brake thermal efficiency (BTE) while reduced certain exhaust emissions. Results of AVL SPC 472_MCE97 analysis showed that the addition of NE can reduce the overall smoke value by 44%. The smoke emission decreased at the maximum torque speed (1500 rpm) rather than at the rated power speed (2200 rpm).     

Simulation analysis of cooling methods of an on‐board organic Rankine cycle exhaust heat recovery system

Energy saving and emission reduction of engines were taken seriously, especially for vehicular diesel engines. Exhaust heat recovery based on organic Rankine cycle (ORC) system has been considered as an effective approach for improving engine fuel economy. This article presents the investigation of water or air cooling method for an ORC exhaust heat recovery system on a heavy‐duty truck through simulations. The models of the truck engine and the ORC system were developed in GT suite, and the integration system model was developed in the Simulink environment. The validity of the models was verified experimentally. The performance of the vehicular engine with ORC system using water or air cooling method was comparatively analyzed. The simulation results indicated that the water cooling method is more suitable for the vehicular ORC system than air cooling method. The relation between benefit and penalty of the ORC system and cooling system was discussed. The operating condition of the cooling system was confirmed having significant effects on the combined system performance, especially the fan speed. The performance improvement of the engine with the use of ORC system was further evaluated under different engine operating conditions and ambient temperatures. Lower ambient temperature had positive effects on the engine fuel economy. The mass flow rate of exhaust gas for heat recovery should be regulated for better performance under high ambient temperature.     

可变几何排气管增压系统与其他增压系统的对比计算研究

为了解决某船用8缸机高低负荷兼顾的问题,提出了1种全新的可变几何排气管增压系统,它通过安装在排气管上的可控阀门来实现增压方式的转换。利用GT-POWER对可变几何排气管增压系统进行了计算研究,根据油耗最优原则找出其阀门开和阀门关之间的切换点在50%负荷;又分别对四脉冲增压系统、PC系统、MPC系统和MIXPC系统进行了计算研究。计算结果表明:在25%、50%、75%、100%负荷,可变几何排气管增压系统的油耗均小于四脉冲增压系统、MPC增压系统和MIXPC增压系统的油耗,扫气系数均大于四脉冲增压系统、MPC增压系统和MIXPC增压系统的扫气系数。     

乳化油对柴油机油耗和环保性能影响的再研究

在单缸四冲程直喷式柴油机上研究了有、无水存在的情况下,乳化油对柴油机的排放和油耗的影响,并与纯柴油的情况进行了对比,实验结果表明．水能够同时降低NOx及碳烟排放．且有较大幅度的下降,但油耗则在不同条件下有所不同、从实际使用考虑,建议使用掺混20％～30％水的乳化油,这样对油耗、排放都是有利的。     

Influence of addition of hydrogen produced on board in the performance of a stationary diesel engine

A stationary diesel engine is tested using HHO produced on board by a commercial electrolytic cell as additive. The cell uses KOH as electrolytic and is connected to the engine battery. Experiments show the cell efficiency is better when current is 6–10 A. Engine was tested in several load regimes, measuring fuel consumption and others parameters, including vibration. Results shows that BSFC and thermal efficiency with HHO improves an average of 3,81% and 2,79% respectively, depending on engine regime and load. Vibration is evaluated using RMS and peak-to-peak values of vibration acceleration, measured in two points on top and one side of the engine. The addition of HHO reduces vibration in most of the experimental points, ought to a better combustion process of gasoil in presence of hydrogen.     

Experimental investigation of varying composition of HCNG on performance and combustion characteristics of a SI engine

With rapid depletion of petroleum resources, researchers are investigating alternate fuels to meet global transportation energy demand. Gaseous fuels such as compressed natural gas (CNG) and hydrogen are of special interest because of their cleaner combustion characteristics compared to liquid petroleum based fossil fuels. However both these gaseous fuels have some technical issues when they are used as stand-alone alternate fuel in conventional spark ignition (SI) engines. CNG suffers from lower energy density and narrow flammability range whereas backfiring tendency is highly pronounced in hydrogen fueled engines. Hydrogen enriched compressed natural gas (HCNG) mixtures are observed to be good alternative to these individual fuels since these mixtures do not pose the issues experienced by the constituent fuels i.e. CNG and hydrogen. In this study, experiments were conducted in a spark ignited gas engine using various compositions of HCNG mixtures having 0, 10, 20, 30, 50, 70 and 100% (v/v) hydrogen fraction. The performance and combustion characteristics of these test fuels were compared with that of baseline CNG, in order to find an optimum HCNG mixture composition for a single cylinder gas engine. Results obtained showed that 30HCNG mixture delivered superior engine performance compared to other HCNG mixtures and baseline CNG, which is in sharp contrast to 15HCNG being advocated globally.     

Kinetic modeling and experimental study on the combustion,performance and emission characteristics of a PCCI engine fueled with ethanol-diesel blends

The combustion process in the Premixed Charge Compression Ignition (PCCI) engine is basically restricted by the in cylinder charged mixture components. Also, the homogeneity of the charged mixture is determining the quality and process of the chemical reaction during the first stage of combustion which establish the auto-ignition process. In the present work, the engine experimental setup is equipped with a new suggested modification on the original fuel system device in order to produce a perfect commixture of diesel/ethanol at different blends ratio with the charged air. The obtained laboratory results are used to validate the simulation's data of the PCCI engine ignition. The prediction is performed using a detailed kinetic reaction mechanism. The simulation study has been achieved to predict the auto-ignition timing and the combustion characteristics of the PCCI engine fueled with different blends of ethanol and diesel at different volume percentage. The obtained results show that the premixed ratio of the ethanol in the ethanol/diesel fuel blends can be used to control the auto-ignition timing and the combustion characteristics at different engine air/fuel ratios. Also, the main pathway of this work is to establish the influence of the engine operating parameters which including the premixed ratio, fuel–air equivalence ratio on the engine performance, combustion and emission characteristics of the PCCI engine. These effects are studied and traced through the simulation result data of the in-cylinder pressure, temperature, and gas phase heat release at different a premixed ratio of ethanol-diesel fuels blends of 0, 10, 20, 30,40 and 50% (by volume).     

The potential of di-methyl ether (DME) as an alternative fuel for compression-ignition engines: A review

This paper reviews the properties and application of di-methyl ether (DME) as a candidate fuel for compression-ignition engines. DME is produced by the conversion of various feedstock such as natural gas, coal, oil residues and bio-mass. To determine the technical feasibility of DME, the review compares its key properties with those of diesel fuel that are relevant to this application. DME’s diesel engine-compatible properties are its high cetane number and low auto-ignition temperature. In addition, its simple chemical structure and high oxygen content result in soot-free combustion in engines. Fuel injection of DME can be achieved through both conventional mechanical and current common-rail systems but requires slight modification of the standard system to prevent corrosion and overcome low lubricity. The spray characteristics of DME enable its application to compression-ignition engines despite some differences in its properties such as easier evaporation and lower density. Overall, the low particulate matter production of DME provides adequate justification for its consideration as a candidate fuel in compression-ignition engines. Recent research and development shows comparable output performance to a diesel fuel led engine but with lower particulate emissions. NO_x emissions from DME-fuelled engines can meet future regulations with high exhaust gas recirculation in combination with a lean NO_x trap. Although more development work has focused on medium or heavy-duty engines, this paper provides a comprehensive review of the technical feasibility of DME as a candidate fuel for environmentally-friendly compression-ignition engines independent of size or application.     

柴油机采用4台增压器相继增压性能的试验研究

为改善TBD234V12柴油机的低负荷性能,对其进行4台增压器相继增压的设计和改造,并进行试验研究。针对试验结果的比较和分析提出三阶段相继增压的方案,确定三阶段相继增压的切换边界。研究结果表明:采用4台增压器相继增压能明显改善原柴油机的低工况性能,燃油消耗率最高降低了9%,涡前排温最高降低了25%,扭矩范围最大提高了12.6%。