Calculation of Intake Oxygen Concentration through Intake CO2 Measurement and Evaluation of Its Effect on Nitrogen Oxide Prediction Accuracy in a Heavy-Duty Diesel Engine

A new procedure, based on measurement of intake CO2 concentration and ambient humidity was developed and assessed in this study for different diesel engines in order to evaluate the oxygen concentration in the intake manifold. Steady-state and transient datasets were used for this purpose. The method is very fast to implement since it does not require any tuning procedure and it involves just one engine-related input quantity. Moreover, its accuracy is very high since it was found that the absolute error between the measured and predicted intake O2 levels is in the ±0.15% range. The method was applied to verify the performance of a previously developed NOx model under transient operating conditions. This model had previously been adopted by the authors during the IMPERIUM H2020 EU project to set up a model-based controller for a heavy-duty diesel engine. The performance of the NOx model was evaluated considering two cases in which the intake O2 concentration is either derived from engine-control unit sub-models or from the newly developed method. It was found that a significant improvement in NOx model accuracy is obtained in the latter case, and this allowed the previously developed NOx model to be further validated under transient operating conditions.

Platinum Recovered from Automotive Heavy-Duty Diesel Engine Exhaust Systems in Hydrometallurgical Operation

The current study is focused on platinum recovery from the secondary sources of end-of-life heavy-duty diesel oxidation catalysts (DOCs) and heavy-duty catalyzed diesel particulate filters (c-DPFs) in order to reduce the supply–demand gap within the European Union. The extraction of platinum was based on a hydrometallurgical single-step low acidity leaching system (HCl-H2O2-NaCl) and a calcination step that takes place before the leaching process. The parameters of calcination and leaching process were thoroughly investigated in order to optimize recovery efficiency. The optimized results proved that a calcination step (at 800 °C for 2 h) improves the recovery efficiency by a factor of 40%. In addition, optimal Pt recovery yield was achieved after 3 h of leaching at 70 °C, with a solid-to-liquid (S/L) ratio of 70 g/100 mL (70%) and 3 M HCl-1% vol H2O2-4.5 M NaCl as leaching conditions. The optimum Pt recovery yield was 95% and 75% for DOC and c-DPF, respectively. Since the secondary feedstock investigated is highly concentrated in platinum, the pregnant solution can be used as a precursor for developing new Pt-based catalytic systems.

Consideration of the effects of increasing spray cone angle and turbulence intensity on heavy-duty diesel engine pollution and specific outputs using CFD

In this article, the effects of increasing spray cone angle and turbulence intensity on the performance and emission of heavy-duty diesel engine has been examined in two separate stages using AVL-Fire CFD code. First, the injector and its spray have been simulated with various geometries. In this step, the Eulerian-Eulerian model has been applied for injector simulation and the Eulerian -Lagrangian model has been applied for spray simulation. The numerical results of this step indicate that creating swirly flow inside the nozzle decreasing penetration length while, fuel spray cone angle increasing during the injection process. In the subsequent step, the heavy-duty diesel engine has been simulated with its conventional and different nozzle hole geometries. In this step, the Eulerian-Lagrangian model has been applied to simulate the engine cycle. The numerical results of this step show that the nozzle with spiral rifling like guides has better performance and lower emission compared to other nozzle geometries. In this case, the fuel consumption is decreasing 32% than cylindrical nozzle hole, while the engine power and its torque increasing 63%. In addition, the amount of nitrogen oxide (NOx) and carbon monoxide (CO) for the spiral convergent conical nozzle geometry reducing 15% and 30% respectively than cylindrical nozzle hole while engine has no soot emission problem. Diesel injector and engine CFD results and experimental data have been validated from previous researches.

Extreme Miller cycle with high intake boost for improved efficiency and emissions in heavy-duty diesel engines

This study experimentally investigates the impact of extreme Miller cycle strategies paired with high intake manifold pressures on the combustion process, emissions, and thermal efficiency of heavy-duty diesel engines. Well-controlled experiments isolating the effect of Miller cycle strategies on the combustion process were conducted at constant engine speed and load (1160 rpm, 1.76 MPa net IMEP) on a single cylinder research engine equipped with a fully-flexible hydraulic valve train system. Late intake valve closing (LIVC) timing strategies were compared to a conventional intake valve profile under either constant cylinder composition, constant engine-out NOx emission, or constant overall turbocharger efficiency ([Formula: see text]) to investigate the operating constraints that favor Miller cycle operation over the baseline strategy. Utilizing high boost with conventional intake valve closing timing resulted in improved fuel consumption at the expense of sharp increases in peak cylinder pressures, engine-out NOx emissions, and reduced exhaust temperatures. Miller cycle without EGR at constant [Formula: see text] demonstrated LIVC strategies effectively reduce engine-out NOx emissions by up to 35%. However, Miller cycle associated with very aggressive LIVC timings led to fuel consumption penalties due to increased pumping work and exhaust enthalpy. LIVC strategies allowed for increased charge dilution at the baseline NOx constraint of 3.2 g/kWh, resulting in significant fuel consumption benefits over the baseline case without compromising exhaust temperatures or peak cylinder pressures. As Miller cycle implementation was shown to affect the boundary conditions dictating [Formula: see text], the LIVC and conventional IVC cases were studied at an equivalent [Formula: see text] point representative of high boost operation. With high boost, LIVC yielded reduced NOx emissions, reduced peak cylinder pressures, and elevated exhaust temperatures compared to the conventional IVC case without compromising fuel consumption.