| 1. |
- Hong, Beichuan, Ph.D. student, 1989-, et al.
(author)
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An Adaptive Estimation Approach for Integrating Real-World Operation Dynamics in Engine-Out NOx Emission Modeling of a Wheel Loader
- 2024
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In: Emission Control Science and Technology. - : Springer Nature. - 2199-3629 .- 2199-3637.
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Journal article (peer-reviewed)abstract
- Accurately predicting engine-out nitrogen oxides (NOx) emissions on-board is crucial for effective emission control in heavy-duty engines. Real-world engine operating conditions, especially in non-road applications with frequent dynamic changes, can significantly affect NOx emission characteristics. However, these engine emission characteristics are conventionally measured on steady-state or regulated driving cycles, which may not fully reflect the emission levels under real-world operational dynamics. This highlights the necessity of integrating engine performance during transient operation into the NOx prediction model to enhance the accuracy of on-board predictions. This paper introduces a novel data-driven model to predict engine-out NOx emissions during the construction activities of a wheel loader. This paper begins by addressing discrepancies between steady-state map predictions and on-board NOx measurements. To bridge these gaps, the model identifies engine transient operating conditions by analyzing the time derivatives of engine speed and torque. The model structure integrates steady-state and transient emission maps, with the transient map being iteratively refined using the Kalman filter principle, thereby improving its accuracy and robustness in response to engine dynamics. The proposed method maintains a model structure that is easily implemented and similar to conventional steady-state emission maps, while also enabling online self-learning for model parameter updates. Model validation shows that the model has high prediction accuracy and the ability to differentiate between steady-state and transient engine working conditions during construction activities.
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| 2. |
- Hong, Beichuan, Ph.D. student, 1989-, et al.
(author)
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Assessment of Emissions and Energy Consumption for Construction Machinery in Earthwork Activities by Incorporating Real-World Measurement and Discrete-Event Simulation
- 2022
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In: Sustainability. - : MDPI. - 2071-1050. ; 14:9, s. 5326-5326
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Journal article (peer-reviewed)abstract
- Earthwork, an essential activity in most construction projects, consumes large quantities of fossil fuel and produces substantial air pollution with adverse environmental impacts. To achieve more sustainable construction processes, novel methodologies to evaluate and improve the performance of earthwork operations are required. This study quantifies the real-world emissions and fuel consumption of construction equipment within an earthwork project in China. Two wheel loaders and two dump trucks are examined through on-board measurements and in-lab engine tests. The duty cycles of construction equipment are categorized with respect to their power efficiency and working patterns. Moreover, the power-specific and time-based emission factors for these duty cycles are computed and compared with relevant legislative emission limits. Significant emission variations among different duty cycles were found, and the real-world emission measurements exceeded the results from the in-lab test required for emission certification. In addition, a discrete-event simulation (DES) framework was developed, validated, and integrated with the computed emission factors to analyze the environmental and energy impacts of the earthwork project. Furthermore, the equipment fleet schedule was optimized in the DES framework to reduce greenhouse gas emissions and fuel consumption by 8.1% and 6.6%, respectively.
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| 3. |
- Hong, Beichuan, Ph.D. student, 1989-, et al.
(author)
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Crank angle-resolved mass flow characterization of engine exhaust pulsations using a Pitot tube and thin-wire thermocouples
- 2023
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In: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; , s. 121725-121725
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Journal article (peer-reviewed)abstract
- Characterizing pulsating flow in high-temperature, high-pressure engine exhaust gas is crucial for the development and optimization of exhaust energy recovery systems. However, the experimental investigation of engine exhaust pulses is challenging due to the difficulties in conducting crank angle-resolved measurements under these unsteady flow conditions. This study contributes to characterizing mass flow pulses from an isolated cylinder exhaust of a heavy-duty diesel engine using a single-pipe measurement system, developed for pulsating flow measurement. A Pitot tube-based approach is adopted to measure exhaust mass flow pulsations, complemented by fast temperature measurements obtained using customized unsheathed thin-wire thermocouples. The on-engine experiment is performed by isolating the in-cylinder trapped mass and the valve opening speed to produce different exhaust pulse waveforms. The adopted approach’s sensitivity in resolving instantaneous mass flows is evaluated analytically and experimentally, considering attenuated temperature measurement effects. Based on exhaust flow measurements, mass flow pulses are analyzed with regard to blow-down and scavenge phases. Under the load sweep, the main waveform change occurs during the blow-down phase, with pulse magnitude increasing with the load. In contrast, as the engine speeds up with a comparable trapped mass, the exhaust mass distribution in the blow-down phase decreases from 75.5% at 700 rpm to 41.9% at 1900 rpm. Additionally, it is observed that cycle-to-cycle variations in mass flow pulses align with combustion stability during the blow-down phase and are predominantly influenced by gas-exchange processes during the scavenge phase.
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| 4. |
- Hong, Beichuan, Ph.D. student, 1989-, et al.
(author)
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Energy and exergy characteristics of an ethanol-fueled heavy-duty SI engine at high-load operation using lean-burn combustion
- 2023
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In: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; , s. 120063-120063
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Journal article (peer-reviewed)abstract
- Ethanol, as the most produced renewable biofuel, is considered a promising low-carbon alternative to petroleum-based fuels in the transport sector due to its high energy density and auto-ignition resistance. The lean-burn combustion in spark-ignition (SI) engines has the potential to further improve thermal efficiency in regard to knock mitigation and the reduction of combustion temperature. However, the characteristics of lean-burn combustion in an ethanol-fueled engine in relation to the combustion losses and the gas-exchange process remain unclear, especially for high-load operation. This study contributes with a deeper understanding of the high-load performance of an ethanol-fueled heavy-duty SI engine using lean-burn combustion. Based on the experimental results from a single-cylinder engine test, a 6-cylinder engine model is built by integrating a validated predictive combustion model to characterize the lean-burn combustion process. The engine’s thermal efficiency and combustion phasing are evaluated for knock limited operation and then compared to the theoretical optimum which is regardless of knock. The energy and exergy balances are applied to evaluate the effect of dilution with excess air ratios up to 1.8. Losses through heat transfer, exhaust flow, and incomplete combustion are quantified. In addition, entropy generated through combustion is discussed to identify the relationship between exergy destruction and different operating conditions. In the context of lean-burn combustion, the thermal efficiency at high-load operation incrementally increases from 40.4% at stoichiometric condition to 47.3% at an excess air ratio of 1.8. At the same time, the exergy destruction through combustion increases by 3.3 percentage points across the selected dilution range. Furthermore, the challenging requirements to realize lean-burn combustion with lower exhaust gas temperatures and higher intake boost pressures is assessed through an exergy analysis of the turbocharging system.
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| 5. |
- Hong, Beichuan, Ph.D. student, 1989-
(author)
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Exergy Evaluation of Engine Operations : Combustion Process to Exhaust Flow
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Transitioning the transport sector to clean energy sources is crucial for mitigating greenhouse gas emissions and achieving carbon neutrality. A collaborative solution, combining both electric vehicles and combustion engines using renewable fuels, may prove more effective than competitive ones. This necessitates a focus on developing sustainable combustion engines by improving their efficiency through renewable energy sources and innovative technologies.This thesis uses exergy analysis to evaluate engine efficiency, losses, and irreversibilities, as well as the work potential of exhaust flows. Particular emphasis is placed on the implications of these exergy analyses in relation to engine operations, especially concerning combustion processes and exhaust pulsations. Exergy analysis quantifies the maximum work extractable from an energy source, enabling the identification and quantification of losses and inefficiencies in thermal processes. A dual-fuel marine engine with two-stage turbocharging and an ethanol-fueled heavy-duty spark-ignition (SI) engine using lean burn are examined with validated one-dimensional engine models to analyze engine performance and losses from an exergy perspective. In the tested marine engine, irreversibilities are quantified and categorized into three types, with combustion irreversibility being the most significant, followed by losses through gas exchange and heat dissipation. In the ethanol-fueled SI engine, the effect of lean-burn combustion at high load is investigated through the excess air ratio up to 1.8, assessing its impact on thermal efficiency, combustion phasing, as well as energy and exergy distributions. Results indicate that employing lean burn improves engine efficiency with advanced combustion phasing but also leads to more exergy destruction. The importance of maintaining high exergy recovery through turbocharging for diluted operation is also highlighted.Additionally, high-frequency exhaust pulsations resulting from valve motion pose challenges in accurately resolving exhaust energy and exergy. To address this, this thesis investigates methods for exhaust pulse characterization and measurement under unsteady flow conditions. Sensitivity analyses, based on a heavy-duty engine simulation, highlight the importance of time-resolved mass flow measurements in quantifying the energy and exergy of exhaust pulsations. Subsequently, this research implements a Pitot tube-based approach to measure crank angle-resolved engine exhaust mass flow rates and to further analyze the effect of attenuated temperature measurements on resolving instantaneous mass flows. The findings indicate that temperature variations pertaining to exhaust flow conditions have only a relatively small impact on mass flow measurements. Based on the exhaust flow measurements, the mass flow characteristics of exhaust pulsations are also discussed with regard to the blow-down and scavenge phases.
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| 6. |
- Hong, Beichuan, 1989-, et al.
(author)
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Modeling of dynamic NOx emission for nonroad machinery : a study on wheel loader using engine test data and on-board measurement
- 2016
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Conference paper (peer-reviewed)abstract
- Quantification of nonroad machinery emissions is of high importance for improving heavy construction processes especially concerning environmental sustainability. In comparison to the substantial research effort on modeling dynamic emissions for road transport, there is, however, lack of knowledge on how to quantify dynamic emissions during construction operations. This paper proposes an approach to model dynamic NOx emission for nonroad construction machinery using recent experimental data collected by a wheel loader operated in the Chinese environment. In the experiment, emissions were measured during different operational cycles for wheel loader and the data is used for both model calibration and validation. Starting from an initial emission map built from in-lab engine bench test, the model prediction of dynamic NOx emission is calibrated by three real-time engine performance parameters highly correlated to the NOx generation. Considering the characteristics of the nonroad equipment, a dynamic module is added to represent engine state transition due to frequent switching of an operational mode in construction activities, making the whole model more accurate in predicting instantaneous emission levels. Compared to the validation data randomly selected from three different cycle tests, the model shows good performance concerning prediction accuracy and with the capacity of handling drastic changes of the working condition of the machine. While the study focuses on the engine-out NOx emission the resulting methodology can be generalized for emission modeling of other nonroad construction machines.
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| 7. |
- Hong, Beichuan, Ph.D. student, 1989-, et al.
(author)
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Numerical Analysis of Engine Exhaust Flow Parameters for Resolving Pre-Turbine Pulsating Flow Enthalpy and Exergy
- 2021
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In: Energies. - : MDPI AG. - 1996-1073. ; 14:19
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Journal article (peer-reviewed)abstract
- Energy carried by engine exhaust pulses is critical to the performance of a turbine or any other exhaust energy recovery system. Enthalpy and exergy are commonly used concepts to describe the energy transport by the flow based on the first and second laws of thermodynamics. However, in order to investigate the crank-angle-resolved exhaust flow enthalpy and exergy, the significance of the flow parameters (pressure, velocity, and temperature) and their demand for high resolution need to be ascertained. In this study, local and global sensitivity analyses were performed on a one-dimensional (1D) heavy-duty diesel engine model to quantify the significance of each flow parameter in the determination of exhaust enthalpy and exergy. The effects of parameter sweeps were analyzed by local sensitivity, and Sobol indices from the global sensitivity showed the correlations between each flow parameter and the computed enthalpy and exergy. The analysis indicated that when considering the specific enthalpy and exergy, flow temperature is the dominant parameter and requires high resolution of the temperature pulse. It was found that a 5% sweep over the temperature pulse leads to maximum deviations of 31% and 27% when resolving the crank angle-based specific enthalpy and specific exergy, respectively. However, when considering the total enthalpy and exergy rates, flow velocity is the most significant parameter, requiring high resolution with a maximum deviation of 23% for the enthalpy rate and 12% for the exergy rate over a 5% sweep of the flow velocity pulse. This study will help to quantify and prioritize fast measurements of pulsating flow parameters in the context of turbocharger turbine inlet flow enthalpy and exergy analysis.
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| 8. |
- Hong, Beichuan, 1989-, et al.
(author)
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Path optimization for a wheel loader considering construction site terrain
- 2018
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In: 2018 IEEE Intelligent Vehicles Symposium (IV), Changshu, Suzhou, China, 26-30 June 2018. - Changshu, China : IEEE. ; , s. 2098-2103
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Conference paper (peer-reviewed)abstract
- Wheel loader is one of the most widely used heavy-duty vehicles for transporting building materials in construction site. Improvement of its efficiency is important for sustainable transport and construction operations. This paper proposes a path optimization approach that allows us to plan loader trajectory and corresponding vehicle motions in construction site when the topological relief information is available. Vehicle dynamics is modeled for 3D motions considering the power balance of vehicle propulsion. The path planning problem is then formulated using a framework of constrained optimal control where vehicle dynamics is incorporated as system constraints. In order to solve the problem, a discrete search method is developed based on the principle of dynamic programming (DP), in which the states of the forward and backward movement paths of wheel loader are explored in parallel. A numerical study is then presented to demonstrate the application of the proposed approach for optimizing the loader path using terrain information.
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| 9. |
- Hong, Beichuan, 1989-, et al.
(author)
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Quantification of Emissions for non-road Machinery in Earthwork : Modeling and Simulation Approaches
- 2017
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Conference paper (peer-reviewed)abstract
- Earthwork, as an essential part of almost all heavy construction projects, is an energy consuming procedure and pollution source for both transport and construction sectors. Due to the increasing need and interest to achieve sustainable development in construction, the evaluation of emission and energy impact in earthwork is of high importance for improving the environmental sustainability. This paper proposes an approach to estimate emissions and fuel usage of construction equipment by using experimental data collected from a project mainly carried out in China. In the experiment, emissions and operational parameters of two loaders and two hauler trucks were measured and analyzed. Based on the power efficiency and other factors, different operation cycles are defined for wheel loader and trucks in the real measurement. Then, through establishing an estimation approach, the emission and fuel rates for different operational cycles are finally calculated. The results show that there are remarkable differences for emissions under different working conditions. In order to evaluate and reduce the emissions and fuel values of the whole earthwork project, a discrete-event simulation (DES) is developed and employed to simulate the earthwork scenarios in a detailed case study. The model provides a basis for the integration of the emission calculation with earthwork simulation. During the evaluation, an alternative plan has been proposed and analyzed for lowering the environmental impacts of the earthmoving operations.
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| 10. |
- Hong, Beichuan, Ph.D. student, 1989-, et al.
(author)
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Quantification of Losses and Irreversibilities in a Marine Engine for Gas and Diesel Fuelled Operation Using an Exergy Analysis Approach
- 2020
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Conference paper (peer-reviewed)abstract
- Large bore marine engines are a major source of fossil fuel consumption in the transport sector. The development of more efficient and cleaner marine engine systems are always required. Exergy analysis is a second-law based approach to indicate the maximum amount of work obtainable from a given system.In this study, an exergy analysis is used to identify losses and improvement potential of a large bore Wärtsilä 31DF four-stroke marine engine system with two-stage turbocharging. An exergy-based framework is implemented on a calibrated 1D engine model to view the evolution of exergy flow over each engine sub-system while operating on different load points fuelled with natural gas and diesel separately.The overall distributions of engine energy and exergy are initially compared at a systematic level regarding the impact of fuel mode and operating load. Furthermore, the engine irreversibilities are characterized as three types: combustion, heat dissipation, and gas exchange losses. The first type, combustion irreversibility, is the largest source of engine exergy losses amounting to at least 25% of fuel exergy. A crank resolved analysis showed that premixed gas combustion produces lower exergy losses compared to diesel diffusion combustion. The second type, thermal exergy transferred and destroyed by heat losses, are summarized for the entire engine system. From the exergy view, the charge coolers present an opportunity to recover about 9% of the brake power at full load. The last type, gas exchange losses, are categorized by accounting the flow losses caused by the valve throttling, fluid friction in pipes and the irreversibility of the two-stage turbocharging system. Most of exergy destruction in gas paths occurs at turbocharging system, where the high pressure turbocharger contributes to around 40% of the total flow exergy destruction.
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