Engine Test Bench Research Articles

Turbocharging strategy among variable geometry turbine, two-stage turbine, and asymmetric two-scroll turbine for energy and emission in diesel engines

Energy saving and emission reduction are very urgent for internal combustion engines. Turbocharging and exhaust gas recirculation technologies are very significant for emissions and fuel economy of internal combustion engines. Various after-treatment technologies in internal combustion engines have different requirements for exhaust gas recirculation rates. However, it is not clear how to choose turbocharging technologies for different exhaust gas recirculation requirements. This work has indicated the direction to the turbocharging strategy among the variable geometry, two-stage, and asymmetric twin-scroll turbocharging for different exhaust gas recirculation rates. In the paper, a test bench engine experiment was presented to validate the numerical models of the three diesel engines employed with the asymmetric twin-scroll turbine, two-stage turbine, and variable geometry turbine. On the basis of the numerical models, the turbocharging routes among the three turbocharging approaches under different requirements for EGR rates are studied, and the other significant performances of the three turbines were also discussed. The results show that there is an inflection point in the relative advantages of asymmetric, variable geometry, and two-stage turbocharged engines. At the full engine load, when the EGR rate is lower than 29%, the two-stage turbocharging technology has the best performances. However, when the exhaust gas recirculation rate is higher than 29%, the asymmetric twin-scroll turbocharging is the best choice and more appropriate for driving high exhaust gas recirculation rates. The work may offer guidelines to choose the most suitable turbocharging technology for engine engineers and manufacturers to achieve further improvements in engine energy and emissions.

Advanced Control Strategies to Improve Nonlinear Automotive Dynamical Systems Consumption

Electric motors and Internal Combustion Engine test benches allow for testing, under various conditions, the behavior of the Electric Vehicles and they are essential in the automotive field development. In this paper, we introduce the state-of-art of the control algorithms and their validation over different test runs, on the standard driving cycles. Ad-hoc simulations and test benches designed for the issue offer a significant opportunity to reduce costs. The modelling of automotive systems is a non-trivial problem due to the non-linearities. The paper presents a linearized solution and an adaptive control scheme to improve model performances starting from real data, and also discusses the behavior of the proposed system and the control law reporting emissions of the considered virtual vehicle when compared with the target emission regulations.

Impact of driving dynamics in RDE test on NOx emissions dispersion

EU6D emission regulation intends to bridge the gap between laboratory tests and the real driving conditions by introducing real drive emission testing. It requires the measurement of real drive emission to be an additional type approval test in order to take into account the influence of road profile, ambient conditions and traffic situations. An important amendment has been included in Commission regulation (European Union) 2016/646, limiting the driving dynamics and hence avoiding the biased testing of the vehicle. In this work, a drive cycle generator has been developed to synthesise cycles meeting all the regulatory requirements of the real drive emission testing. The generator is based on the transition probability matrix obtained from each phase of the World harmonised Light vehicle Test Procedure cycle. Driving dynamics have been varied based on real drive emission regulations, and several trips have been generated with dynamics ranging from soft to aggressive. A direct injection compression ignition 1.5 L engine with a state-of-the-art aftertreatment system has been utilised to run the generated synthetic cycles. The analysis of the results obtained in the tests (all of them complying with real drive emission restrictions in terms of driving dynamics) points out a noticeable 60% relative dispersion in the NO x emissions downstream of the catalyst. The contribution of the proposed method lies not only in the fact that it synthesises driving cycles as stochastic process and is capable of tuning the driving dynamics based on real drive emission regulations, but it also presents the range of dispersion possible in NO x emissions solely due to the driving dynamics. The methodology followed in the present work could be an essential step in future engine developments, where testing engine prototypes on the entire range of driving dynamics in the engine test bench facility could provide interesting insights about the expected NO x emissions in real drive emission testing.

Selective catalytic reduction of nitrogen oxides with methanol over the (cobalt-molybdenum)/alumina dual catalysts under the diesel methanol dual fuel exhaust conditions

The (cobalt-molybdenum)/alumina ((Co-Mo)/Al2O3) dual catalysts have an excellent performance on the selective catalytic reduction (SCR) of nitric oxide with methanol (methanol-SCR) on the synthetic gas test bench. The catalytic performance of (Co-Mo)/Al2O3 needs to be studied on the engine test bench due to the complicated emissions of engines. Tests were carried out on the diesel methanol dual fuel (DMDF) engine. The effect of methanol supply methods, methanol dosing, injection timings of diesel fuel and exhaust gas recirculation (EGR) ratios on the performance of methanol-SCR was investigated. Results show that the performance of methanol-SCR on the engine test bench slightly deteriorates compared with that on the synthetic gas test bench. The performance of methanol-SCR on the active methanol supply mode is superior to that on the passive methanol supply mode. The low nitrogen oxides (NOX) conversion with passive methanol supply mode suggests that the ratio of carbon monoxide to hydrocarbons (more than 1) and the ratio of nitrogen dioxide to NOX are the critical factors on NOX conversion during the catalyst selection. However, the passive methanol supply mode has less effect on the fuel consumption. The catalytic efficiency of methanol-SCR is improved by the increased methanol dosing and EGR ratios and the retarded injection timings. The methanol dosing increases the particulate emissions and the fuel consumption. Increasing EGR ratios is less bad for the fuel consumption than retarding injection timings. A combination of the DMDF engine and the methanol-SCR realizes the ultra-low NOX emissions.

Development of physics-based three-way catalytic converter model for real-time distributed temperature prediction using proper orthogonal decomposition and collocation

To meet the increasingly demanding emissions and fuel economy standards, the thermal management of the aftertreatment devices has recently become a priority in powertrain control. In particular, the longitudinal distribution of temperature in the three-way catalyst is a critically important variable to monitor for catalyst light-off control, thermal protection, and for diagnosing aging and degradation. However, such information is typically unavailable in production applications, due to the cost and reliability issues of instrumenting the three-way catalyst with multiple temperature sensors. This work focuses on the development and the experimental validation of a control-oriented, physics-based thermal model of a three-way catalyst for the purpose of real-time temperature monitoring. Starting from the governing equations in partial differential equation form, a model order reduction technique that combines proper orthogonal decomposition and collocation is developed. The sensitivity of the selection of the empirical basis functions is studied. To include the exothermic effect from chemical reactions, a fully connected artificial neural network is trained. The reduced-order model executes more than 100 times faster when compared to the use of standard numerical methods and commercial simulation software such as GT-Power, while providing comparable accuracy. Finally, to verify the proposed methodology, the model is calibrated and validated against experimental data collected by instrumenting a three-way catalyst with multi-point temperature measurements, and installed on an engine test bench.

Improvement of Transient Operation Controllability in Engine Test Bench for Heavy-Duty Vehicles

In this study, two kinds of control methods for the transient operation of an engine test bench for heavy-duty vehicles were applied in the JE05 test cycle and World Harmonized Transient Cycle (WHTC) test conditions in order to evaluate the controllability of transient operations and the effect on emissions. One control method uses dynamometer torque with its inertia correction as the feedback signal (dyno torque F/B control); the other method uses axial torque measured by a flange-type high-response torque meter as the feedback signal (axial torque F/B control). The transient operation controllability using the axial torque F/B control improved compared with the dyno torque F/B control. The results influence NOx emissions in the emissions test cycle, such as JE05 and WHTC, with the engine test bench. Axial torque F/B control could become a more useful technique when it is required to improve the reproducibility of real driving conditions.

Exhaust emissions of diesel engines with nano-copper additives

The effects of nano-copper additives were investigated through a thermogravimetric (TG) test, diesel engine bench test, and road driving test. The tests demonstrated that the nano-copper additive presented a good catalytic effect on the combustion of soot particles, which reduced the complete combustion temperature from 580 to 520 °C. The diesel engine bench test showed that particulate matter (PM), CO, and HC emissions were reduced by 99.9%, 81.30%, and 33.33%, respectively. The NOx emissions slightly increased due to the lack of carbon as a reducing substance in the exhaust gas. The road driving test with a diesel vehicle demonstrated that more stringent emission standards can be met without any upgrade to the engine.

Analiza wymiany ciepła w układzie napędowym pojazdu drogowego z retarderem

The paper presents a heat exchange model for the cooling system of any complex, physical system. Verification of the correctness of the theoretical model was carried out on the example of a vehicle with a combustion engine and additionally equipped with a hydraulic retarder. The results of laboratory tests, which were carried out on an engine test bench, were also performed for the above mentioned powertrain, so as to compare the results of modelling with the results of the tests. Determining the operating parameters of the components of the cooling system aimed at protecting the entire powertrain against overheating is a key task. Theoretical analysis of heat exchange in the powertrain of a road vehicle was carried out, with particular emphasis on the hydraulic retarder (a device braking the vehicle during a descent on roads with a high gradient of the road, mandatory according to the ADR convention). The subject of the study was a mathematical model of a complex cooling system developed by the authors, described by means of balance equations and differential equations. This model was tested with the use of the Matlab-Simulink suite for given load parameters of the cooling system, which were used in tests on an engine test bench. The values of coefficients describing the thermal state of the powertrain were obtained. Simulations were performed for different variants of technical parameters of the expanded cooling system. In this way, individual units and components of the cooling system were optimized so that it fulfilled its role in the assumed operating conditions and the ecologization of emission of energy sources (fuel) and harmful substances.

Experimental study of lubricant-derived ash effects on diesel particulate filter performance

Diesel particulate filters are indispensable for diesel engines to meet the increasingly stringent emission regulations. A large amount of ash would accumulate in the diesel particulate filter over time, which would significantly affect the diesel particulate filter performance. In this work, the lubricant-derived ash effects on diesel particulate filter pressure drop, diesel particulate filter filtration performance, diesel particulate filter temperature field during active regeneration, and diesel particulate filter downstream emissions during active regeneration were studied on an engine test bench. The test results show that the ash accumulated in the diesel particulate filter would decrease the diesel particulate filter pressure drop due to the “membrane effect” when the diesel particulate filter ash loading is lower than about 10 g/L, beyond which the diesel particulate filter pressure drop would be increased due to the reduction of diesel particulate filter effective volume. The ash loaded in the diesel particulate filter could significantly improve the diesel particulate filter filtration efficiency because it would fill the pores of diesel particulate filter wall. The diesel particulate filter peak temperature during active regeneration is consistent with the diesel particulate filter initial actual soot loading density prior to regeneration at various diesel particulate filter ash loading levels, while the diesel particulate filter maximum temperature gradient would increase with the diesel particulate filter ash loading increase, whether the diesel particulate filter is regenerated at the same soot loading level or the same diesel particulate filter pressure drop level. The ash accumulation in the diesel particulate filter shows little effects on diesel particulate filter downstream CO, total hydrocarbons, N2O emissions, and NO2/NO x ratio during active regeneration. However, a small amount of SO2 emissions was observed when the diesel particulate filter ash loading is higher than 10 g/L. The ash accumulated in the diesel particulate filter would increase the diesel particulate filter downstream sub-23 nm particle emissions but decrease larger particle emissions during active regeneration.

Pressure Drop of Particulate Filters and Correlation with the Deposited Soot for Heavy-Duty Engines

<div class="section abstract"><div class="htmlview paragraph">Particulate filters are a widely used emission control device on heavy-duty diesel engines. The accumulation of particulate matter, mostly consisting of soot, inside the filter results in increased filter pressure-drop (backpressure). This increased backpressure has been used by the on-board control systems as trigger for regeneration procedures, which aim to actively oxidize the accumulated soot. However, it is known that passive soot oxidation during normal operation affects the correlation between backpressure and the deposited soot mass in filter. Therefore, the backpressure alone cannot be a reliable trigger for regeneration. In this work we highlight operating conditions with very poor correlation between backpressure and accumulated soot mass in filter and evaluate the possible root causes.</div><div class="htmlview paragraph">Experiments with several heavy-duty diesel engines and particulate filters were conducted on engine test bench. These experiments involved prolonged operation under conditions emulating real-world operation. Under certain conditions, the backpressure of the filter did not correlate with the accumulated soot mass: although the soot mass increased monotonically, reaching the regeneration soot mass limit, the measured backpressure corresponded to the backpressure of an almost clean filter. The quality of correlation was found to depend on the operating conditions, PM/NOx engine out emissions as well as on the type of filter used.</div><div class="htmlview paragraph">To investigate these complex interactions, we used an extensive experimental protocol to calibrate a physico-chemically informed mathematical model of the soot oxidation and the soot properties in the filter. We employed this model to investigate the possible reasons for the apparent lack of correlation between backpressure and accumulated soot mass. The simulation study confirmed the experimental findings: even minor passive soot oxidation may destroy the correlation between soot loading and filter backpressure. Moreover, simulation revealed the relative contribution of the following factors on the filter backpressure: microscopically, changes in the properties of the deposited soot, due to oxidation and compaction; macroscopically, non-uniform soot distribution inside the filter channels, due to transient flow and passive soot oxidation. Finally, simulations showed that the ratio of incoming soot from the engine to oxidizing soot in filter has a major impact on the potential to re-establish a correlation between soot loading and backpressure.</div></div>

Experimental Investigation and Benchmark Study of Oxidation of Methane–Propane–n-Heptane Mixtures at Pressures up to 100 bar

Dual fuel combustion exhibits a high degree of complexity due to the presence of different fuels like diesel and natural gas in initially different physical states and a spatially strongly varying mixing ratio. Optimizing this combustion process on an engine test bench is costly and time consuming. Cost reduction can be achieved by utilizing simulation tools. Although these tools cannot replace the application of test benches completely, the total development costs can be reduced by an educated combination of simulations and experiments. A suitable model for describing the reactions taking place in the combustion chamber is required to correctly reproduce the dual fuel combustion process. This is why in the presented study, four different reaction mechanisms are benchmarked to shock tube (ST) and rapid compression machine (RCM) measurements of ignition delay times (IDTs) at pressures between 60 and 100 bar and temperatures between 671 and 1284 K. To accommodate dual fuel relevant diesel-natural gas mixtures, methane–propane–n-heptane mixtures are considered as the surrogate. Additionally, the mechanisms AramcoMech 1.3, 2.0 and 3.0 are tested for methane–propane mixtures. The influence of pressure and propane/n-heptane content on the IDT based on the measurements is presented and the extent to which the mechanisms can reflect the IDT-changes discussed.

Determination of CO2 Emissions for Selected Flight Parameters of a Business Jet Aircraft

Abstract In the last two decades, there has been observed a noticeable increase in the popularity and availability of air transport services, including regional ones. This intensive development of transport is accompanied by an increase in the adverse impact to the environment, increases noise level, and exhausts emissions, despite the modification and modernization of engines. Determining the emission for regional flights takes into account the specificity of the aircrafts design, such as the size of the aircraft and the performance of the engines. In this article, an attempt was made to determine the CO2 emissions of a business jet flying from Gdansk to Rzeszow. The methodology of the research (the method of calculating emissions based on fuel consumption) and the performance characteristics of the aircraft engines have been described. In the first part of the article, the speed-altitude characteristics of the DGEN-380 engine for different cruise parameters were determined using the virtual engine test bench WESTT CS/B. These characteristics have enabled the engine to match the flight characteristics (altitude, speed). For specific flight parameters, the thrust and fuel consumption were determined. On this basis, for the adopted trajectory and flight time of an aircraft equipped with two DGEN-380 engines, total fuel consumption and CO2 emission factors and values in CRUISE phase was determined with regard to the wind speed and direction. The obtained results were illustrated graphically and discussed.

Effectiveness of hybrid powertrains to reduce the fuel consumption and NOx emissions of a Euro 6d-temp diesel engine under real-life driving conditions

Recent investigations demonstrated that the real-world driving conditions differ from those proposed in the homologation cycles. This provokes that the emissions levels in real-life conditions exceed the normative values, as shown in the recent scandal related to the NOx emissions from the passenger cars equipped with diesel engines. On the other hand, the upcoming emissions regulations will limit the CO2 emissions to very low levels, which demands a further optimization of the existing technology. One way to reduce the NOx and CO2 emissions is by electrifying the powertrain in a certain degree. The objective of this work is to evaluate the potential of implementing a parallel (P2) hybrid architecture in a compact car (class C) equipped with a diesel 1.6 Euro 6d-temp engine to reduce the emissions and fuel consumption in homologation and real-life driving cycles. This has been done using a 0D numerical vehicle model and the experimental engine maps of fuel consumption and emissions measured at steady state conditions. After that, the transient conditions were simulated in homologation cycles and real-life driving cycles measured by the authors in Spain. The numerical model was validated against experimental tests carried out in an active engine test bench, evidencing differences below 4% under the worldwide harmonized light vehicles test cycle (WLTC). In the real-life cycles, the hybridization of the powertrains improves the fuel consumption for all types of driving cycles (urban, combined and highway). The major benefits are obtained in urban driving cycles, with gains up to 50% in fuel consumption and CO2 emissions. In addition, the improvements in real-life conditions are higher than in the urban phase of the homologation cycles. On the contrary, combined real-life cycles (urban + rural + highway) show lower benefits than the homologation cycle. This is due to different energy management strategy that needs to be adapted to each driving situation. Lastly, it was found that, contrarily to the case of the homologation cycle, the NOx emissions are not reduced with the hybridization of the diesel powertrain in real-life conditions. Thus, to achieve 2021 CO2 target (95 g/km) and to reduce aftertreatment systems in diesel engines, other vehicles technologies need to be added to the full hybridization.

Control and measurement systems for spark ignition rotary engine

To precisely control and measure the performance of a single-rotor spark ignition rotary engine, a control system and measurement system were developed. A redundant design for hardware and software of sensors was applied. A symmetrical layout formed by two crankshaft position sensors was used to generate square wave signals that were complementary and inputted into the electric control unit as the crankshaft position reference. The corresponding software timing strategy and fault diagnosis were designed. Based on a simulation test and engine bench test, the electric control system shows a reasonable control effect, and the engine performance parameters including output torque, intake air flow and pressure, fuel and oil consumption, cooling air and coolant flow, and excess air ratio indicate that the engine control system and measurement system can operate smoothly.

Characterization of Emissions in Low Displacement Diesel Engines Using Biodiesel and Energy Recovery System

This study has been devoted to the investigation of the use of an exhaust gas energy recovery system in a test bench of a single-cylinder diesel engine in four different modes of operation, in search of the potential for recovery energy in these classes of devices, the influence of fuel on their efficiency and the influence of the device in the reduction of polluting emissions. For this reason, a thermoelectric generator is constructed, which is mainly made up of an internal rectangular duct-type heat exchanger and twenty thermoelectric modules installed on the upper and the lower side of the heat exchanger in a 5×2 arrangement. A data acquisition system is connected to the thermoelectric generator and it allows monitoring the electrical power generated by the thermoelectric modules, the temperatures of the exhaust gases at the inlet and outlet of the heat exchanger, and the polluting emissions. The maximum net electrical power recovered has been of 65.28 W and 57.8 W for the B5 and the B10, respectively. The maximum value of energy recovery obtained leads to a decrease in fuel and a reduction in CO2, CO, HC, NOx, and NO emissions of 2.43% and 2.65% for B10 and B5.

Simulation of the flow field and the chemical reaction coupling of selective catalytic reduction (SCR) system using an orthogonal experiment.

It is difficult to simulate both the flow field and the chemical reaction using, respectively, the flow state and kinetics calculations and actually reflect the influence of the gas flow state on the chemical change in a selective catalytic reduction (SCR) system. In this study, the flow field and the chemical reaction were therefore coupled to simulate a full Cu-Zeolite SCR system and the boundary conditions of the simulation were set by a relevant diesel engine bench test which included the exhaust temperature, the mass flow, and the exhaust pressure. Then, the influence of the gas flow state on the NOx conversion efficiency was investigated. Specifically, an orthogonal experimental design was used to study the influence of the injection parameters (position, angle, and speed) on the NH3 distribution by establishing the NH3 uniformity coefficient γ at the SCR catalyst capture surface in the flow field simulation. Then, the velocity capture surface of the SCR catalyst front section was sliced into coupled data transfer interfaces to study the effects of exhaust temperature, ammonia to NOx ratio (ANR), and the NO2/NOx on the NOx conversion efficiency. This was used as guidelines to optimize the SCR system control strategy. The results showed that a 1150 mm injection position, a 45°injection angle, and a 23 m/s injection velocity provided the most uniform NH3 distribution on the SCR catalyst capture surface. For constant injection parameters, the NOx conversion efficiency was the highest when the exhaust temperature was 200°C—400°C, the ANR was 1.1, and NO2/NOx was 0.5.

Urea injection control strategy in urea-selective catalytic reduction for heavy-duty diesel engine under transient process

A urea injection control strategy for urea-selective catalytic reduction under a transient process is investigated on a heavy-duty diesel engine test bench in this study. The aim is to improve NO x conversion efficiency and reduce ammonia slip. With the selective catalytic reduction system as the research object, an open thermodynamic conservation system is established. The conservation relationship in the process of urea injection, NO x reduction reaction, ammonia storage, and ammonia slip is investigated. The ideal target ammonia storage area and the ammonia storage characteristics during the transient process are studied. The ammonia storage area and boundary, which change with the transient temperature, are established. Correction of real-time ammonia injection is further deduced from the boundary of the area. The world harmonized transient cycle test cycle result showed that compared to feed-forward control, the NO x conversion efficiency increased by 16% and the NH3 slip decreased by 75% when using the proposed real-time ammonia storage-management control method.

The Nonlinear Single Controller of DGEN380 Aero Engine Design

The advanced nonlinear sliding mode control method of DGEN380 aero engine is presented in this paper. This aero engine is a small high bypass ratio turbofan engine by which the nonlinear control approach of the aero engine is invested. And this paper focuses on the power management function of the aero engine control system which includes steady control and transient control. The mathematical model of DGEN380 aero engine is built by a set of nonlinear dynamic equation that is validated by experimental data. The single controller based on sliding mode approach is designed that can keep some certain thrust levels during steady state and maintain repeatable performance during transient operation from one requested thrust level to another. The single controller can offset the impact of the signal noise and harmonic disturbance at a certain power point. And the dynamic performance of the single controller is satisfactory at the transient process. The experiment is conducted by aero engine test bench for the single control.

Issues of emission evaluation of road-rail vehicles in the aspect of current type approval regulations

One of the ways to reduce exhaust emissions from vehicles is to replace worn-out shunting locomotives with road-rail tractors. The main purpose of this solution is to reduce the negative environmental impact of the vehicle and to reduce the fuel consumption compared to a shunting locomotive performing the same work. The tests on exhaust emissions of rail vehicles are carried out on an engine test bench, making it impossible to determine the environmental performance of these vehicles during real operation. Therefore, it is advisable to carry out measurements in real operating conditions in order to obtain reliable reference results. This enables the verification of vehicles ecological indicators in a wide range of operational work parameters. It is possible to obtain reliable results regarding the impact of the tested vehicle on the natural environment in this way and compare them with the applicable emission standards.

Exhaust emission from a vehicle engine operating in dynamic states and conditions corresponding to real driving

The article presents the exhaust emission results from a diesel engine in dynamic states of engine operation in the driving tests: NEDC (New European Driving Cycle) and Malta test, developed at the Poznan University of Technology. The NEDC and Malta tests were carried out as simulations on the engine test bench mimicking the driving tests conditions. The test results of the emission of carbon monoxide, hydrocarbons and nitrogen oxides obtained in each of the tests were presented. The dynamic states have been classified de-pending on the time derivative value of the torque and engine rotational speed. Both the positive and negative as well as zero time deriv-ative values of torque and rotational speed were considered. Therefore, overall six types of dynamic states were analyzed. A high sensi-tivity of exhaust emission to various types of dynamic states was found. The exhaust emission sensitivity to dynamic states in the Malta test was found to be higher than for the NEDC test, although these tests have similar properties (average rotational speed and average torque). This is due to the fact that the NEDC test is created on the basis of the similarity of zero-dimensional characteristics of the cars speed characteristic, whereas the Malta test was designed in accordance with the principle of faithful representation in the time domain of the NEDC speed curve.