Performance, combustion and emission characteristics investigations on a diesel engine fueled with diesel/ ethanol /n-butanol blends

Ammonia (NH3), as a carbon-free fuel with a high hydrogen content, has been considered as a promising candidate to be applied for transportation, propulsion, and power generation sectors. However, due to the presence of nitrogen atoms, direct combustion of NH3 features a high NOx emission, which could hinder its wide application. Thus it is important to mitigate or minimize these emissions. For this, a three-dimensional (3D) computational model is developed by considering a detailed chemical-kinetic mechanism. The effects of 1) the perforated plate porosity σ , 2) the perforated plate thickness t1, 3) the perforated orifice off-z axis distance d, and 4) inlet thermodynamic pressure Pin are evaluated. Numerical results indicate that σ plays an important role in determining the NO formation. This is the combined effect of the strong species preferential diffusion and low flame temperature within the recirculation zone. Furthermore, varying t1 is shown to affect the NO generation rate due to the varied recirculation zone. Although the flow field is affected by d to some degree, it has a negligible effect on the NO generation. Finally, the emission behavior is found to have a strong dependence on Pin. Approximately 50% reduction of NO emission is achieved as the inlet pressure is varied from 1 to 3 atm. The present work opens up an applicable way to enable low-NOx ammonia-fueled power systems, and some of the findings could be applied for hydrocarbon systems design.

Evaluation of NOx emissions characteristics in a CO2-Free micro-power system by implementing a perforated plate

As a hydrogen energy carrier and carbon-free fuel, ammonia (NH3) is being growingly considered as an alternative fuel for combustion systems in an effort to reduce carbon emissions. Unlike conventional fossil fuels, its relatively low flame speed hinders its widespread use in practice. Utilizing the 1D freely propagating flame model in Chemkin-Pro 2019, this work numerically evaluates the impact of blending ammonia with dimethyl ether (DME) on the laminar burning velocity of NH3/air flames. For this, the reaction mechanism is first validated by comparing predictions to experimental data available in the literature. The addition of DME is found to significantly enhance the laminar burning velocity (SL) of NH3 flames, which can be comparable to that of hydrocarbon fuels. This enhancement is a result of the combined thermal and chemical effects. Reaction pathway and sensitivity analyses reveal that adding DME enables the major reaction steps and the sensitivities to be altered, thus positively affecting the overall reaction rate. Furthermore, the SL of NH3/air flames is weakly dependent on the inlet thermodynamic pressure, but becomes stronger with more DME blended. The explanation behind this phenomenon is that the relative importance of the termination versus branching reactions is more significant in binary flames. The overall reaction order characterizing the importance of the chain branching and the terminating reactions shows a decreasing trend with increasing inlet pressure. In general, the present work provides a design guideline on the selection of fuel flexibility and sheds light on the fundamental NH3-DME-fueled flame enhancement mechanisms. 

Enhancing and assessing ammonia-air combustion performance by blending with dimethyl ether

Effects of different poses and wind speeds on wind-induced vibration characteristics of a dish solar concentrator system

Investigation on the combustion and emission characteristics of diesel engine fueled with diesel/methanol/n-butanol blends

The effects of Fe2O3 based DOC and SCR catalyst on the combustion and emission characteristics of a diesel engine fueled with biodiesel

The NH3 uniformity and conversion rate produced by the urea–water solution spray system is an essential factor affecting de-NOx efficiency. In this work, a three-dimensional simulation model was developed with the CFD software and was employed to investigate the effects of two typical injection methods (wall injection and center injection) and three distribution strategies (pre-mixer, post-mixer, pre-mixer, and post-mixer) of two typical mixers on the urea conversion rate and uniformity. The field synergy principle was employed to analyze the heat transfer of different mixer flow fields. The results show that the single mixer has instability in optimizing different injection positions due to different injection methods and injection positions. The dual-mixer is stable in the optimization of the flow field under different conditions. The conclusion of the field synergy theory of the single mixer accords with the simulation result. The Fc of the dual-mixer cases is low, but the NH3 conversion and uniformity index rate are also improved due to the increase in the residence time of UWS.

Jiedong Ye

Papers

The effects of Fe2O3 based DOC and SCR catalyst on the combustion and emission characteristics of a diesel engine fueled with biodiesel

Numerical Analysis on Enhancing Spray Performance of SCR Mixer Device and Heat Transfer Performance Based on Field Synergy Principle

Optimization of the Urea Scr Injector Based on Entropy Generation Minimization and Entransy Dissipation Extremum