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Unburned hydrocarbon (UHC) and carbon monoxide (CO) emission sources are examined in an optical, light-duty diesel engine operating under low load and engine speed, while employing a highly dilute, partially premixed low-temperature combustion (LTC) strategy. The impact of engine load and charge dilution on the UHC and CO sources is also evaluated. The progression of in-cylinder mixing and combustion processes is studied using ultraviolet planar laser-induced fluorescence (UV PLIF) to measure the spatial distributions of liquid- and vapor-phase hydrocarbon. A separate, deep-UV LIF technique is used to examine the clearance volume spatial distribution and composition of late-cycle UHC and CO. Homogeneous reactor simulations, utilizing detailed chemical kinetics and constrained by the measured cylinder pressure, are used to examine the impact of charge dilution and initial stoichiometry on oxidation behavior.

The drive to reduce particle emissions from heavy-duty diesel engines has reached the stage where the contribution from the lubricant can have a major impact on the total amount of particulate matter (PM). This paper proposes a model to predict the survival rate (unburnt oil divided by oil consumption) of the hydrocarbons from the lubricant consumed in the cylinder. The input data are oil consumption and cylinder temperature versus crank angle. The proposed model was tuned to correlate well with data from a six-cylinder heavy-duty diesel engine that meets the Euro 5 legislation without exhaust gas aftertreatment. The measured (and modelled) oil survival shows a strong correlation with engine power. The maximum oil survival rate measured (19%) was at motoring conditions at high speed. For this engine, loads above 100 kW yielded an oil survival rate of nearly zero.

Continuous efforts to develop a lightweight alloy suitable for the most demanding applications in automotive industry resulted in a number of advanced aluminum (Al) and magnesium alloys and manufacturing routes. One example of this is the application of 319 Al alloy for production of 3.6L V6 gasoline engine blocks. Aluminum is sand cast around Fe-liner cylinder inserts, prior to undergoing the T7 heat treatment process. One of the critical factors determining the quality of the final product is the type, level, and profile of residual stresses along the Fe liners (or extent of liner distortion) that are always present in a cast component. In this study, neutron diffraction was used to characterize residual stresses along the Al and the Fe liners in the web region of the cast engine block. The strains were measured both in Al and Fe in hoop, radial, and axial orientations. The stresses were subsequently determined using generalized Hooke's law.

The development of an optimized heat treatment schedule, with the aim of maximizing strength and relieving tensile residual stress, is important to prevent in-service cylinder distortion in Al alloy engine blocks containing cast-in gray iron liners. However, to effectively optimize the engine block heat treatment schedule, the current solutionizing parameters must be analyzed and compared to the as-cast condition to establish a baseline for residual stress relief. In this study, neutron diffraction was carried out to measure the residual stress along the aluminum cylinder bridge following solution heat treatment. The stresses were measured in the hoop, radial and axial orientations and compared to a previous measured as-cast (TSR) engine block. The results suggest that solution heat treatment using the current production parameters partially relieved tensile residual stress in the Al cylinder bridge, with stress relief being more effective near the bottom of the cylinder.

In the last couple of decades, countries have enacted new laws concerning environmental pollution caused by heavy-duty commercial and passenger vehicles. This is done mainly in an effort to reduce smog and health impacts caused by the different pollutions. One of the legislated pollutions, among a wide range of regulated pollutions, is nitrogen oxides (commonly abbreviated as NOx). The SCR (Selective Catalytic Reduction) was introduced in the automotive industry to reduce NOx emissions leaving the vehicle. The basic idea is to inject a urea solution (AdBlue™) in the exhaust gas before the gas enters the catalyst. The optimal working temperature for the catalyst is somewhere in the range of 300 to 400 °C. For the reactions to occur without a catalyst, the gas temperature has to be at least 800 °C. These temperatures only occur in the engine cylinder itself, during and after the combustion.

An afterburner-assisted turbocharged single-cylinder 425 cc two-stroke SI-engine is described in this simulation study. This engine is intended as a Backup Range Extender (REX) application for heavy-duty battery electric vehicles (BEV) when external electric charging is unavailable. The 425 cc engine is an upscaled version of a 125 cc port-injected engine [26] which demonstrated that the selected technology could provide a specific power level of 400 kW/L and the desired 150 kW in a heavy duty BEV application. The 425 cc single cylinder two-stroke engine is an existing engine as one half of a 850 cc snowmobile engine. This simulation study includes upscaling of the swept volume, impact on engine speed and gas exchange properties. In the same way as for the 125cc engine [26], the exhaust gases reaches the turbine through a tuned exhaust pipe and an afterburner or oxidation catalyst.

Diffusive combustion of direct injected ethanol is investigated in a heavy-duty single cylinder engine for a broad range of operating conditions. Ethanol has a high potential as fossil fuel alternative, as it provides a better carbon footprint and has more sustainable production pathways. The introduction of ethanol as fuel for heavy-duty compression-ignition engines can contribute to decarbonize the transport sector within a short time frame. Given the resistance to autoignition of ethanol, the engine is equipped with two injectors mounted in the same combustion chamber, allowing the simultaneous and independent actuation of the main injection of pure ethanol and a pilot injection of diesel as an ignition source. The influence of the dual-fuel injection strategy on ethanol ignition, combustion characteristics, engine performance and NOx emissions is evaluated by varying the start of injection of both fuels and the ethanol-diesel ratio.

Renewable fuels from different feedstocks can enable sustainable transport solutions with significant reduction in greenhouse gas emissions compared to conventional petroleum-derived fuels. Nevertheless, the use of biofuels in diesel engines will still require similar exhaust gas cleaning systems as for conventional diesel. Hence, the use of diesel particulate filters (DPF) will persist as a much needed part of the vehicle’s aftertreatment system. Combustion of renewable fuels can potentially yield soot and ash with different properties as well as larger amounts of ash compared to conventional fossil fuels. The faster ash build-up and altered ash deposition pattern lead to an increase in pressure drop over the DPF, increase the fuel consumption and call for premature DPF maintenance or replacement. Prolonging the maintenance interval of the DPF for heavy-duty trucks, having a demand for high up-time, is highly desirable.

Diesel engine manufacturers strive towards further efficiency improvements. Thus, reducing in-cylinder heat losses is becoming increasingly important. Understanding how location, thermal insulation, and engine operating conditions affect the heat transfer to the combustion chamber walls is fundamental for the future reduction of in-cylinder heat losses. This study investigates the effect of a 1mm-thick plasma-sprayed yttria-stabilized zirconia (YSZ) coating on a piston. Such a coated piston and a similar steel piston are compared to each other based on experimental data for the heat release, the heat transfer rate to the oil in the piston cooling gallery, the local instantaneous surface temperature, and the local instantaneous surface heat flux. The surface temperature was measured for different crank angle positions using phosphor thermometry.

Natural gas (NG)-diesel dual-fuel combustion can be a suitable solution to reduce the overall CO2 emissions of heavy-duty vehicles using diesel engines. One configuration of such a dual-fuel engine can be port injection of NG to form a combustible air-NG mixture in the cylinder. This mixture is then ignited by a direct injection of diesel. Other potential advantages of such an engine include the flexibility of switching back to diesel-only mode, reduced hardware development costs and lower soot emissions. However, the trade-off is lower brake thermal efficiency (BTE) and higher hydrocarbon emissions, especially methane, at low load and/or high engine speed conditions. Advancing the diesel injection timing tends to improve the BTE but may cause the NOx emissions to increase.

Biofuel can enable a sustainable transport solution and lower greenhouse gas emissions compared to standard fuels. This study focuses on biodiesel, implemented in the easiest way as drop in fuel. When mixing biodiesel into diesel one can run into problems with solubility causing contaminants precipitating out as insolubilities. These insolubilities, also called soft particles, can cause problems such as internal injector deposits and nozzle fouling. One way to overcome the problem of soft particles is by filtration. It is thus of great interest to be able to quantify fuel filters’ ability to intercept soft particles. The aim of this study is to test different fuel filters for heavy-duty engines and their ability to filter out synthetic soft particles. A custom-built fuel filter rig is presented, together with some of its general design requirements. For evaluation of the efficiency of the filters, fuel samples were taken before and after the filters.

Development of lightweight alloys suitable for automobile applications has been of great importance to the automotive industry in recent years. The use of 319 type aluminum alloy in the production of gasoline engine blocks is an example of this shift towards light alloys for large automobile components. However, excessive residual stress along the cylinder bores of these engine blocks may cause problems during engine operation. Therefore, in this study, neutron diffraction was used to evaluate residual stresses along the aluminum cylinder bridge and the gray cast iron liners. The strains were measured in the hoop, radial, and axial orientations, while stresses were subsequently calculated using generalized Hooke's law. The results suggest that the residual stress magnitude for the aluminum cylinder bridge was tensile for all three measured components and gradually increased with cylinder depth towards the bottom of the cylinder.

In recent years, light weight components have been an area of significant importance in automotive design. This has led to the replacement of steel and cast iron with aluminum alloys for many automotive components. For instance, Al-Si alloys have successfully replaced nodular and gray cast iron in the production of large automotive components such as engine blocks. However, excessive residual strain along the cylinder bores of these engine blocks may result in cylinder distortion during engine operation. Therefore, in this study, neutron diffraction was used to evaluate residual strain along the aluminum cylinder bridge and the gray cast iron liners of distorted and undistorted engine blocks. The strains were measured in the hoop, radial, and axial orientations. The results suggest that the residual strain along the aluminum cylinder bridge of the distorted engine block was tensile for all three measured components.

Partially Premixed Combustion (PPC) is a combustion concept which aims to provide combustion with low smoke and NOx with high thermal efficiency. Extending the ignition delay to enhance the premixing, avoiding spray-driven combustion and controlling the combustion temperature at an optimum level through use of suitable lambda and EGR levels have been recognized as key factors to achieve such a combustion. Fuels with high ignitability resistance have been proven to be a useful to extend the ignition delay. In this work pure ethanol has been used as a PPC fuel. The objective of this research was initially to investigate the required operating conditions for PPC with ethanol. Additionally, a sensitivity analysis was performed to understand how the required parameters for ethanol PPC such as lambda, EGR rate, injection pressure and inlet temperature influence the combustion in terms of controllability, stability, emissions (i.e.

In the automotive industry, the piezo-based in-cylinder pressure sensor is getting commercialized and used in production vehicles. For example, the pressure sensor offers the opportunity to design algorithms for estimation of engine emissions, such as soot and NO , during a combustion cycle. In this paper a zero-dimensional NO model for a diesel engine is implemented that will be used in real time. The model is based on the thermal NO formation and the Zeldovich mechanism using two non-geometrical zones: burned and unburned zone. The influence of EGR on combustion temperature was modeled using a well-known thermodynamic identity where specific heat at constant pressure is included. Specific heat will vary with temperature and the gas composition. The model was implemented in LabVIEW using tools specific for an FPGA (Field-Programmable Gate Array).

This paper investigates the FPGA resources for the implementation of in-cycle closed-loop combustion control algorithms. Closed-loop combustion control obtains feedback from fast in-cylinder pressure measurements for accurate and reliable information about the combustion progress, synchronized with the flywheel encoder. In-cycle combustion control requires accurate and fast computations for their real-time execution. A compromise between accuracy and computation complexity must be selected for an effective combustion control. The requirements on the signal processing (evaluation rate and digital resolution) are investigated. A common practice for the combustion supervision is to monitor the heat release rate. For its calculation, different methods for the computation of the cylinder volume and heat capacity ratio are compared. Combustion feedback requires of virtual sensors for the misfire detection, burnt fuel mass and pressure prediction.

In this article, a virtual sensor for the estimation of the injected pilot mass in-cycle is proposed. The method provides an early estimation of the pilot mass before its combustion is finished. Furthermore, the virtual sensor can also estimate pilot masses when its combustion is incomplete. The pilot mass estimation is conducted by comparing the calculated heat release from in-cylinder pressure measurements to a model of the vaporization delay, ignition delay, and the combustion dynamics. A new statistical approach is proposed for the detection of the start of vaporization and the start of combustion. The discrete estimations, obtained at the start of vaporization and the start of combustion, are optimally combined and integrated in a Kalman Filter that estimates the pilot mass during the vaporization and combustion. The virtual sensor was programmed in a field programmable gate array (FPGA), and its performance tested in a Scania D13 Diesel engine.

This study reports gaseous and particle (ultrafine and black carbon (BC)) emissions from a turbofan engine core on standard Jet A-1 and three alternative fuels, including 100% hydrothermolysis synthetic kerosene with aromatics (CH-SKA), 50% Hydro-processed Esters and Fatty Acid paraffinic kerosene (HEFA-SPK), and 100% Fischer Tropsch (FT-SPK). Gaseous emissions from this engine for various fuels were similar but significant differences in particle emissions were observed. During the idle condition, it was observed that the non-refractory mass fraction in the emitted particles were higher than during higher engine load condition. This observation is consistent for all test fuels. The 100% CH-SKA fuel was found to have noticeable reductions in BC emissions when compared to Jet A-1 by 28-38% by different BC instruments (and 7% in refractory particle number (PN) emissions) at take-off condition.

The present paper aims at discussing the flow/flame interaction in a lean burn spark ignition engine. The mean velocity and cycle resolved turbulence are measured with laser Doppler velocimetry. The cylinder pressure is recorded and a one-zone heat release calculation performed. The very early part of flame propagation is measured using two orthogonal Schlieren systems, each capturing one image of the progressing flame at a given time after spark onset. The two resulting 2D images are then, after preprocessing, used to reconstruct the three-dimensional flame. The volume of the true flame is estimated by simulating, using Markov Chain Monte Carlo techniques, a number of possible flames that are consistent with the projections on the images. The uncertainty of the estimated flame volume is given by the variation of the volume estimates. In the calculations, the volume of that part of the spark plug that is inside the flame is subtracted.

The effects of cetane number and the cetane enhancing additives on diesel exhaust emissions were investigated on a single cylinder DI research engine. The engine used in this study incorporates the features of contemporary medium-to-heavy duty diesel engines and is tuned to US EPA 1994 emission standards. The engine experiments were run using the AVL 8-mode steady-state simulation of the U.S. EPA heavy-duty transient test procedure. The experimental fuels included diesel fuels obtained from different sources with various natural cetane ratings as well as a number of fuels blended by adding two cetane improvers into three base fuels. The two cetane improvers we used were a nitrate-type additive and a peroxide-type additive. Increasing the cetane number resulted in a general decrease in NOx emissions. Similar reductions in NOx emissions were observed with increasing cetane number for all the base fuels irrespective of the cetane improver used in the fuel.