Optimal Energy Recovery Research Articles

Analysis of the Heat Content of Exhaust Gases from a Heavy-Duty Diesel Engine under Real-world Driving Conditions and Cold Start Operation

Abstract European Commission is currently working on defining new Euro 7 standards for light and heavy-duty vehicles, which will set severe restrictions on emissions in real driving conditions, and under cold-start operations. It is well known that about 60% of fuel energy converted in a diesel engine is lost in exhaust flow, coolant, and other forms of loss. A more efficient vehicle usage can be achieved by exploiting such dissipated energy content to produce additional mechanical or electrical energy. Several solutions can be adopted for Waste Heat Recovery (WHR) systems. Among them, exploiting the synergy between Organic Rankine Cycles (ORCs), thermal storage with Phase Change Materials (PCM), and electric hybridization is the solution adopted in the research project IRIDESCENT (biodIesel hybRID Electric buS with waste heat reCovEry aNd sTorage). The efficacy of recovering heat content from exhaust gases in reducing fuel consumption has already been demonstrated under stationary conditions. However, one of the challenges in applying WHRs to the powertrain of road vehicles is the fast dynamics of the engine load that determines fast variations in the flow rate and temperature of the exhaust gases. This makes it difficult to optimize energy recovery and explains the need to adopt PCM thermal storage systems. In this framework, the goal of the present work is to characterize the variability of temperature and flow rate in the exhaust gases of a diesel engine for heavy-duty applications under real-world driving conditions. To this end, a dataset of information retrieved from the scientific literature for the Isuzu FTR850 truck was used. The dataset consists of twenty-eight trips performed with the same driver over the same route. It includes both hot-start and cold-start trips and three different values of trailer load (0, 1500, 3000 kg). For each trip, data from GPS, ambient sensors, onboard diagnostics (OBD) systems, and portable emissions measurement systems are made available with a frequency of 1 Hz. In this investigation, a statistical analysis of the data set and a preliminary selection of the ORC and PCM technologies are performed.

Metaheuristic optimizing energy recovery from plastic waste in a gasification-based system for waste conversion and management

In an era where sustainable waste management and clean energy production are paramount, this study presents an innovative integration of plastic waste gasification with solid oxide fuel cell (SOFC) technology, optimized through metaheuristic particle swarm optimization (PSO). The research explores the conversion of polypropylene (PP) waste into syngas via gasification, which is then utilized as a fuel for SOFCs to generate electricity. The optimization process focuses on maximizing power and heating outputs while minimizing carbon dioxide emissions. The study's findings demonstrate the potential of integrating gasification and SOFC technologies to create a sustainable energy system that addresses the challenges of plastic waste. Key findings from the metaheuristic PSO multi-objective optimization reveal that optimal power production, approximately 360 kW, is achieved at temperatures exceeding 1140 K, irrespective of the steam/PP waste ratio. Heating production peaks at 1000 kW with temperatures above 1120 K and utilization factors over 0.765, while the minimum heating output is 700 kW. Emission analysis indicates a significant reduction in carbon dioxide emissions with increased temperatures and utilization factors, achieving a minimum of 700 kg/MWh at temperatures above 1120 K. The study's results demonstrate the effectiveness of the PSO optimization in fine-tuning the operational parameters of the integrated system, leading to improved energy efficiency and reduced environmental impact. Power production of 366.37 kW, a significant heating rate of 995.20 g/s, and emissions of 714.06 kg/MWh are the optimum performances. The research provides valuable insights into the potential of plastic waste-to-energy technologies as sustainable solutions for energy production and waste management.

General integration method for system configuration of organic Rankine cycle based on stage-wise concept

Organic Rankine Cycle (ORC) integrated systems with heat sources consist of heat exchange processes and thermodynamic power conversion processes. Fully exploring feasible system configuration while considering fluid selection is crucial for enhancing ORC power generation and balancing economic costs. This study innovatively proposes a theoretical framework that decomposes the Rankine cycle into basic thermodynamic processes. The design of system configuration is regarded as the adjustment of the series-parallel relationships of these basic processes, aiming to achieve simultaneous optimization of the cycle structure and the HEN structure, thereby greatly expanded the search space for feasible ORC system configurations. The optimization problem is solved using a bi-level strategy, The outer layer determines the number of thermal power conversion components, operating parameters, and working fluid selection, then provides the associated stream information to the inner layer for optimizing the heat exchange scheme. Applying this method to two different case studies from the literature validated its effectiveness in optimizing scenarios with single and complex heat sources. The Pareto frontier obtained under the conditions of Case I indicates that the investment cost can be reduced by $33.04 k/yr while maintaining the same net power output. In exchange for an increase of $1.51 k/yr in investment cost, the maximum net power output can be improved by 124.74 kW. Under the conditions of Case II, the maximum net output power can increase by 9.71 %–52.5 %, and the Pareto frontier featuring outputs exceeding 50 kW is provided. By analyzing the relative positions of literature schemes and Pareto front within the solution space, the impact of system configuration improvements on the objective functions is explained. These results confirm the effectiveness of the proposed approach for designing optimal ORC energy recovery systems for heat sources. This contribution advances optimization methods for similar closed cycle configurations, which is significant for advancing the utilization of waste heat and addressing sustainability challenges.

An innovative approach to municipal solid waste characterization for waste-to-energy processes in Egypt

This study enhances municipal solid waste (MSW) characterization methodologies by introducing an innovative sampling approach that prioritizes organic content over traditional components like paper and cartons, particularly suited to developing countries like Egypt. This innovative method adapts the ASTM D5231 − 92 standard to capture the actual MSW profile in the Giza governorate, where this research was carried out. Focusing on organic waste, this approach ensures more relevant and accurate data for waste-to-energy (WtE) conversion processes. This research documents significant seasonal variability in waste composition, with organic content averaging 66 % in winter compared to 59 % in fall. The energy-rich fraction shows similar variability, with winter having an average of 28 % compared to fall's 30 %. Moreover, the calorific value is notably higher in winter at 10.3 MJ/kg, compared to 8.4 MJ/kg in fall. These variations are critical for optimizing energy recovery processes in WtE projects. The results from this case study contribute to the limited but growing body of knowledge on waste management in Egypt, demonstrating the feasibility and benefits of adapting standard characterization methods to local conditions. The insights gained from this research fill a notable gap in the regional waste management literature and enhance the scientific understanding of how seasonal factors affect MSW properties, providing a robust framework for improving waste management practices in similar settings globally.

Downshifting strategy of plug-in hybrid vehicle during braking process for greater regenerative energy

The P2 configuration plug-in hybrid electric vehicle (P2-PHEV) equipped with a multi-speed transmission has a high potential for recovering more regenerative energy, as the shifting strategy can be employed to adjust the working zone of the electric motor (EM). However, the existing shifting strategy designed for normal driving conditions cannot achieve optimal regenerative energy recovery. In this study, a shifting strategy used in the regenerative braking process is proposed. First, to make the EM provide more regenerative force during braking, a braking force distribution algorithm is devised while simultaneously considering braking stability and safety. Second, to realize maximum regenerative braking energy recovery, an optimal shifting strategy is designed for regenerative braking. Third, the classical braking process is analyzed and six thresholds are abstracted and optimized to establish a rule for restraining frequent gearshifts raised in the proposed optimal shifting strategy. Finally, the proposed strategy is verified under three standard cycles, results show that the proposed shifting strategy can recover considerable regenerative energy without frequent gearshifts.

Optimizing energy recovery from agroforestry waste: Char and inorganic influence on reactivity through co-gasification with coal

Amidst growing global concerns for environmental sustainability and the urgent need for renewable energy sources, this research delves into alternative energy solutions using agricultural byproducts. It specifically focuses on utilizing agroforestry waste as a key component in the development of efficient and eco-friendly energy conversion technologies. The study systematically investigates the co-gasification of agroforestry waste with coal, aiming to optimize structure to significantly enhance energy conversion efficiency. The structural evolution of char and its impact on gasification performance was studied by blending agroforestry waste from lily leaves (LIL) with Yuxi coal (YXC) at different ratios. The experiments reveal that the blend ratio (3:1) significantly enhances the gasification reactivity of YXC. At a temperature of 1000 °C, the reactivity index, R0.9, was found to be 2.59 times greater than that of YXC alone, indicating a substantial improvement in reactivity. This enhanced reactivity is attributed to notable alterations in the microstructure and pore distribution within the blended char. This blended char exhibited a higher prevalence of disordered structures and more volatile functional groups (C–O and CC) and phases enhance the complexity of catalytic actions, facilitating gasification reactions. This research underscores the potential of integrating agroforestry waste into energy production systems as a sustainable solution that optimizes energy conversion processes and contributes to environmental preservation, aligns with the global pursuit of eco-friendly energy alternatives.

Integrating physical knowledge and artificial intelligence approaches for simulation and optimization of direct urea fuel cell

Direct urea fuel cell (DUFC) has recently gained attention as a potentially effective fuel cell because of urea’s ease of use, low-cost, high-energy density, and toxicity-free nature. To develop a fast and accurate mathematical tool to model and optimize the performance of DUFC, this study, for the first time, combined the kinetic model and artificial intelligence approaches. Accordingly, an artificial neural network (ANN) model was developed based on the synthetic datasets produced from the verified kinetic model and then was optimized by particle swarm optimization to determine the optimal conditions for DUFC. The peak power density output and substrate-based energy recovery were chosen as the target functions that depend on several fundamental operating and designing parameters (i.e., types of catholyte, membrane thickness, diffusion layer thickness and porosity, feeding flow rate, temperature, urea and KOH concentrations). Along with significantly reducing the computational simulation time to the kinetic model (from 1500 s to 2 s), the proposed approach exhibited superior accuracy compared to the response surface methodology. With nickel nanoparticles as the anode catalyst material and pure oxygen as the catholyte, the highest power density output and energy recovery from DUFC were predicted at 15.1 mW/cm2 and 19.6 %, respectively. On the other hand, with the natural air supply, the optimal power density and energy recovery values were only 14.4 mW/cm2 and 18.9 %, respectively, due to lower oxygen concentration. These poor performances suggest that more efficient catalyst materials for DUFC need to be further investigated and applied.

EXPLORING FACTORS AFFECTING NITROGEN ISOLATION BY CATION EXCHANGE MEMBRANE AND THEIR IMPLICATIONS FOR MICROBIAL FUEL CELL PERFORMANCE IN WASTEWATER TREATMENT

This study explores the utilization of a cation exchange membrane (CEM) in a microbial fuel cell (MFC) system to isolate nitrogen from wastewater influents. While employing a CEM in an MFC system has drawbacks, such as increased internal resistance and reduced power output, it also provides a means for optimal energy recovery from organics while allowing isolated nitrogen to be treated in subsequent steps. This study evaluated the diffusion of ammonium through CEM in a dual-chamber MFC under different operating conditions. Results indicated that the MFC reactor with CEM as a separator isolated 88-93% of the nitrogen input, demonstrating the feasibility of this approach for nitrogen separation in wastewater treatment applications. Factors affecting nitrogen isolation, including COD input at the anode, dissolved oxygen (DO) at the cathode, and external resistance (ER), are identified. Higher COD input at the anode and the DO at the cathode were found to enhance nitrogen separation, while increased ER had an adverse effect on nitrogen isolation capacity. Additionally, changes in the surface characteristics of the CEM during operation could impact nitrogen isolation, emphasizing the need for careful monitoring and maintenance of the CEM to ensure consistent performance over time. In conclusion, this study highlighted the potential of using a CEM in MFC systems for nitrogen isolation, provided insights into the factors affecting the efficacy of nitrogen separation, and underscored the need for monitoring and maintenance of the CEM. These results could significantly impact the development of more efficient and sustainable wastewater treatment using the MFC system.

Cooperative optimization of energy recovery and braking feel based on vehicle speed prediction under downshifting conditions

Regenerative braking can effectively recover vehicle kinetic energy, but its energy conversion efficiency is low under low-speed conditions, and there is also the problem of premature exit from energy recovery due to insufficient reverse electromotive force. The cooperation of gearbox gears can increase the speed range for the motor to recover energy, but unreasonable shifting will cause fluctuations in braking force and affect the consistency of the braking feel. Therefore, this paper aims to collaboratively optimize energy recovery and braking force fluctuations during gear shifting. Firstly, based on the model of braking system and transmission, the influence of shift strategy on braking impact and energy recovery is studied. In view of the challenge of determining a shift strategy with uncertain target braking speeds, a speed prediction model reconstructed by the support vector regression (SVR) model and the hybrid nonlinear autoregressive neural network (NAR) is proposed. On the basis of NAR-SVR speed prediction, the coupling effect of braking impact force and energy recovery efficiency is considered, and the collaborative optimization of regenerative braking torque and shift time is solved through a multi-objective cuckoo search algorithm. The hardware-in-the-loop test results verified that under high-speed conditions, the braking energy recovery rate of the proposed strategy was increased by 47.06 %, and the peak braking impact was reduced by 61.4 %. This research can provide a reference for the brake downshift optimization strategy and regenerative braking research of vehicles with non-decoupled electro-hydraulic composite braking systems.

Co-digestion of filter cake, biogas effluent, and anaerobic sludge for hydrogen and methane production: Optimizing energy recovery through two-stage anaerobic digestion

This study assesses a two-stage anaerobic digestion process designed to efficiently recover energy through hydrogen and methane production by co-digesting filter cake (FC), biogas effluent (BE), and anaerobic sludge (AS) from the sugar and ethanol industry. The optimal proportions of FC, BE, and AS were determined in batch fermentation experiments using Design Expert software, which identified a suitable ratio of 31.05:28.95:0.00 (g VS/L), respectively. The results indicated that hydrogen production in the first stage could occur solely through the hydrogenic bacteria present in the BE and FC mixture, without the need for AS as an inoculum. This optimized FC:BE ratio was then applied in a semi-continuous fermentation system, achieving a hydrogen production rate of 193.6 mL H2/L.d and a hydrogen yield of 9.8 mL H2/g VS at an optimal hydraulic retention time (HRT) of 3 d. In the subsequent second stage, the effluent from the hydrogen reactor was used for methane production. This stage achieved a methane production rate of 422.0 mL CH4/L·d and a methane yield of 140.2 mL CH4/g VS, with an HRT of 20 d. Overall, the two-stage process exhibited an impressive energy output, peaking at 5.17 kJ/g VS. This suggests the potential for an annual electricity generation of 194,655 MWh and an estimated reduction of 85,668 tCO2eq/year in greenhouse gas emissions. This study highlights the efficiency of the two-stage anaerobic digestion process for harnessing energy through the co-digestion of FC and BE, without the need for additional AS inoculum. The findings demonstrate the potential for sustainable energy recovery from industrial waste streams while mitigating environmental impacts.

Enhancing energy recovery from Wastewater Treatment Plant sludge through carbonization

The Wastewater Treatment Plant (WWTP) uses a dewatering machine to separate sludge from water. The resulting sludge is used as raw material for Refuse Derived Fuel (RDF), while the separated water is treated in the subsequent WWTP unit. However, the sludge from the WWTP is currently only processed into briquettes as per policy and then disposed of in landfills. Our investigation centers on the effects of carbonization temperature on sludge characteristics in a dewatering unit. Initial analysis revealed that 1-day-old sludge possesses a high moisture content (87.72 %) and a low calorific value (3.44 MJ/kg). Carbonization at 300 °C significantly enhanced the sludge's calorific value to 12,504 MJ/kg, reduced its moisture content to 60.72 %, and increased its carbon percentage to 22.76 %, indicating a direct correlation between carbonization temperature and both energy recovery and carbon content. Comparative analysis showed sludge carbonized at lower temperatures (200 °C and 100 °C) yielded lower carbon percentages (22.23 % and 21.66 %, respectively) and energy values, underscoring the efficiency of higher temperature carbonization in optimizing energy recovery.. This research contributes to developing sustainable organic waste recycling practices and supports achieving Sustainable Development Goals 11 and 12 targets. This research promotes sustainable development by improving sludge utilization from WWTPs as a raw material for energy production rather than being directly disposed of in landfills. This study provides insight into the potential for energy recovery from organic waste, technology, and policy's role in achieving a circular economy.

Mathematical Analysis of the Electromotive Induced Force in a Magnetically Damped Suspension

This study explores the advanced mathematical modeling of electromagnetic energy harvesting in vehicle suspension systems, addressing the pressing need for sustainable transportation and improved energy efficiency. We focus on the complex challenge posed by the non-linear behavior of magnetic flux in relation to displacement, a critical aspect often overlooked in conventional approaches. Utilizing Taylor expansion and Fourier analysis, we dissect the intricate relationship between oscillation and electromagnetic damping, crucial for optimizing energy recovery. Our rigorous mathematical methodology enables the precise calculation of the average power per cycle and unit mass, providing a robust metric for evaluating the effectiveness of energy harvesting. Further, the study extends to the practical application in a combined system of passive and electromagnetic suspension, demonstrating the real-world viability of our theoretical findings. This research not only offers a comprehensive solution for enhancing vehicle efficiency through advanced suspension systems but also sets a precedent for the integration of complex mathematical techniques in solving real-world engineering challenges, contributing significantly to the future of energy-efficient automotive technologies. The cases reviewed in this article and listed as references are those commonly found in the literature.

Optimizing Energy Recovery from Marine Diesel Engines: A Thermodynamic Investigation of Supercritical Carbon Dioxide Cycles

Optimizing Energy Recovery from Marine Diesel Engines: A Thermodynamic Investigation of Supercritical Carbon Dioxide Cycles

Enhancing wood efficiency through comprehensive wood flow analysis: Methodology and strategic insights

Wood, an essential natural resource in human civilization, remains widely used despite advances in technology and material substitution. The surge in greenhouse gas emissions and environmental concerns accentuates the need for optimizing wood utilization. Material flow analysis is a powerful tool for tracking material flows and stocks, aiding resource management and environmental decision-making. However, the full extent of its methodological dimensions, particularly within the context of the wood supply chain, remains relatively unexplored. In this study, we delve into the existing literature on wood flow analysis, discussing its primary objectives, materials involved, temporal and spatial scales, data sources, units, and conversion factors. Additionally, data uncertainty, data reconciliation and crucial assumptions in material flow analysis are highlighted in this paper. Key findings reveal the significance of wood cascading and substitution effects by replacing non-wood materials, where they can reduce greenhouse gas emissions more than the natural carbon sink of forests and wood products. The immediate impact of short-term wood cascading might not be as robust as the substitution effect, with energy substitution showcasing better results than material substitution. However, it's crucial to note that these conclusions could experience significant reversal from a long-term and global perspective. Strategies for improving wood efficiency involve maximizing material use, advancing construction technologies, extending product lifespans, promoting cascade use, and optimizing energy recovery processes. The study underscores the need for standardized approaches in wood flow analysis and emphasizes the potential of wood efficiency strategies in addressing environmental challenges.

Novel Microfluidic Septum to Optimize Energy Recovery in Single-Chamber Microbial Fuel Cells

This study proposes a redesign of asymmetric single-chamber microbial fuel cells (a-SCMFCs) with the goal of optimizing energy production. In the present work, the new approach is based on the introduction of a novel intermediate microfluidic septum (IMS) inside the electrolyte chamber. This IMS was designed as a relatively simple and inexpensive method to optimize both electrolyte flow and species transfer inside the devices. a-SCMFCs, featuring the IMS, are compared to control cells (IMS-less), when operated with sodium acetate as the carbon energy source. Performances of cells are evaluated in terms both of maximum output potential achieved, and energy recovery (Erec) as the ratio between the energy yield and the inner electrolyte volume. The a-SCMFCs with the novel IMS are demonstrated to enhance the energy recovery compared to control cells exhibiting Erec values of (37 ± 1) J/m3, which is one order of magnitude higher than that achieved by control cells (3.0 ± 0.3) J/m3. Concerning the maximum output potential, IMS cells achieve (2.8 ± 0.2) mV, compared to control cells at (0.68 ± 0.07) mV. Furthermore, by varying the sodium acetate concentration, the Erec and maximum potential output values change accordingly. By monitoring the activity of a-SCMFCs for over one year, the beneficial impact of the IMS on both the initial inoculation phase and the long-term stability of electrical performance are observed. These improvements support the effectiveness of IMS to allow the development of efficient biofilms, likely due to the reduction in oxygen cross-over towards the anode. Electrochemical characterizations confirm that the presence of the IMS impacts the diffusion processes inside the electrolytic chamber, supporting the hypothesis of a beneficial effect on oxygen cross-over.

Promotion of bio-oil production from the microwave pyrolysis of cow dung using pretreated red mud as a bifunctional additive: Parameter optimization, energy efficiency evaluation, and mechanism analysis

To address the issues of high oxygen content and energy consumption in the microwave-assisted pyrolysis of biomass for biofuel production, this study used high-temperature pretreated red mud (RM) as an additive. The pretreated RM exhibited dual functionalities, namely microwave absorption and catalytic properties, during the microwave-assisted pyrolysis of cow dung (CD). This study also evaluated the optimization potential of energy recovery efficiency. The results showed that the addition of pretreated RM significantly increased the oil yield during the microwave-assisted pyrolysis of CD. The highest oil yield (59.63%) was obtained via the microwave-assisted pyrolysis of CD over catalysis with RM pretreated at 750 °C (RM750). Through the optimization of the RM750-to-CD mixing ratio, optimal oil quality and energy recovery efficiency were achieved. At a mixing ratio of 1:1, the pyrolysis oil featured the highest aromatic hydrocarbon content and lowest acid content. The high-temperature pretreatment of RM increased the Fe2O3 content, which enhanced the dielectric properties and magnetic loss ability of the reactants. This resulted in localized high temperatures and the formation of “hot spots,” which can promote the deoxygenation and hydrogenation reactions of oil. Consequently, the lower heating rate of oil increased from 35.12 to 40.11 MJ kg−1. The released oxygen escaped in the form of CO. In addition, pyrolytic char was used as an in situ microwave absorbing material owing to its increased Fe2O3 content and graphitization degree, leading to an increase in energy recovery efficiency from 4.71% to 9.98%. This study provides valuable guidance for the efficient utilization of diversified solid wastes and demonstrates the potential application of microwave-assisted pyrolysis technology in the resource utilization of solid wastes.

Comparison of exergy and exergy economic evaluation of different geothermal cogeneration systems for optimal waste energy recovery

Since energy sources are limited, any activity aimed at recycling energy waste or facilitating energy conversion systems is invaluable. Against this background, most scientists focus on the integration of energy systems and the coupling of different technologies. In this study, a variety of power systems are investigated for optimal power conversion configurations of geothermal sources. Three configurations, Organic Rankine Cycle Geothermal Cooling (GPR/ORC), Kalina Cycle Geothermal Cooling (GPR/Kalina), and Rankine Cycle and Feed water Heater (GPR/FWH) Geothermal Cooling, are classified according to exergy and Study energy economic analysis. Calculations show that the GPR/FWH system has the highest net output power of 2963 kW. In addition, the GPR/Kalina system has the lowest output power and lowest energy efficiency among the systems launched. Across the three proposed systems, the fuel cell generates 1254 kW of electricity, while the Kalina cycle in the GPR/Kalina system generates 487 kW. Exergy studies show that the GPR/Kalina and GPR/FWH systems have the lowest and highest irreversibility (3795.4 kW and 4365.56 kW, respectively). Furthermore, the fuel cell was found to have the greatest exergy destruction rate among the three configurations. The results of the economic analysis show that the fuel cell has the highest cost ratio among all designs. In addition, the values of the dissipation factor show that the absorption chiller has the highest dissipation factor value among the three configurations. Furthermore, the comparative parametric analysis provides new aspects to introduce into the system.

An operation strategy towards efficient energy recovery from integrated anaerobic digestion and pyrolysis of corn stalk

In this work, an integrated process of anaerobic digestion (AD) and pyrolysis (PY) was developed to eliminate the obstacles of single AD or PY application, such as long period, low efficiency and poor quality of products. The influence mechanism of different AD times on the energy recovery of integrated process was explored, and alkali pretreatment was performed to optimize energy recovery. Results showed that the fluctuation of indicators mainly concentrated in the initial stage of AD due to the limited biodegradability of substrate. The PY characteristics was altered due to the decrease of volatiles with AD time. The energy recovery decreased first and then increased, and tended to be stable on day 25–30 (About 11–12 MJ/kg). Cumulative methane production was the crucial factor for coupling time node with a correlation coefficient of 0.9299–0.9278. This study provides theoretical guidance and insights for efficient energy recovery from integrated AD and PY.

Modelling and Performance Analysis of Cyclic Hydro-Pneumatic Energy Storage System Considering the Thermodynamic Characteristics

The energy storage system of electric-drive heavy mining trucks takes on a critical significance in the characteristics including excellent load capacity, economy, and high efficiency. However, the existing battery-based system does not apply to harsh cold environments, which is the common working condition for the above trucks. A type of cycle hydro-pneumatic energy storage system for the trucks was proposed in this study. The dynamic model of the system, including the dynamic and thermodynamic models of hydraulic and pneumatic parts, was built to analyze the performance of the system. Subsequently, the thermodynamic characteristics were clarified during the energy storage and released through the real test condition-based simulation. The power and energy performances of the system were studied in practice based on the above characteristics. The analysis of the results showed that the system reduced 22.03% driving power at the optimal braking energy recovery rate, the energy density was nearly 12.6 MJ/m3, the maximum input power was higher than 230 kW, and the cycle efficiency was about 40.6%. The results of this study will be conducive to the application of the hydro-pneumatic energy storage system for the electric-drive mining trucks and reducing the resulting carbon emission.

A Platoon Control Method Based on DMPC for Connected Energy-Saving Electric Vehicles

This article presents a distributed model predictive control (DMPC) algorithm with energy management for the electric vehicle platoon. In addition, a braking force distribution strategy is proposed for the following vehicles (FVs) in the platoon, and the optimal energy recovery braking force distribution is adopted within the limits permitted by braking regulations. The cost function of DMPC includes the following aspects: drive/brake power deviation, vehicle distance deviation, trajectory deviation, and energy consumption. Through the simulation analysis, it is demonstrated that the proposed algorithm has satisfactory speed and trajectory tracking performance, platoon stability, and driving comfort. Two platoon control methods [DMPC without energy management, proportion integration differentiation (PID)] and two single vehicle control methods (single vehicle with or without recovery braking) are designed to verify the proposed method. A semiphysical experimental platform is established to verify the authenticity, accuracy, and effectiveness of the model and the proposed control methods.