Realization and Analysis of Good Fuel Economy and Kinetic Performance of a Low-cost Hybrid Electric Vehicle

By using high-power and high-efficiency propulsion systems,current hybrid electric vehicles（HEVs） in market can achieve excellent fuel economy and kinetic performance.However,it is the cost of current HEVs that hinders HEVs coming into widespread use.A novel hybrid electric propulsion system is designed to balance HEV cost and performance for developing markets.A battery/supercapacitor-based hybrid energy storage system（HESS） is used to improve energy conversion efficiency and reduce battery size and cost.An all-in-one-controller（AIOC） which integrates engine electronic control unit（ECU）,motor ECU,and HESS management system is developed to save materials and energy,and reduce the influence of distribution parameters on circuit.As for the powertrain configuration,four schemes are presented：belt-driven starter generator（BSG） scheme,four-wheel drive HEV scheme,full HEV scheme,and ranger-extender electric vehicle（EV） scheme.Component selection and parameter matching for the propulsion system are performed,and an energy management strategy is developed based on powertrain configuration and selected components.Forward-facing simulation models are built,comprehending the control strategy based on the optimal engine torque for the low-cost hybrid electric propulsion system.Co-simulation of AVL CRUISE and Matlab/Simulink is presented and the best scheme is selected.The simulation results indicate that,for the best design,fuel consumption in urban driving condition is 4.11 L/（100 km） and 0-50 km/h accelerating time is 10.95 s.The proposed research can realize low-cost concept for HEV while achieving satisfactory fuel economy and kinetic performance,and help to improve commercialization of HEVs.

A Hybrid Biofuel and Triboelectric Nanogenerator for Bioenergy Harvesting

Various types of energy exist everywhere around us,and these energies can be harvested from multiple sources to power micro-/nanoelectronic system and even personal electronic products.In this work,we proposed a hybrid energy-harvesting system(HEHS)for potential in vivo applications.The HEHS consisted of a triboelectric nanogenerator and a glucose fuel cell for simultaneously harvesting biomechanical energy and biochemical energy in simulated body fluid.These two energy-harvesting units can work individually as a single power source or work simultaneously as an integrated system.This design strengthened the flexibility of harvesting multiple energies and enhanced corresponding electric output.Compared with any individual device,the integrated HEHS outputs a superimposed current and has a faster charging rate.Using the harvested energy,HEHS can power a calculator or a green light-emitting diode pattern.Considering the widely existed biomechanical energy and glucose molecules in the body,the developed HEHS can be a promising candidate for building in vivo self-powered healthcare monitoring system.

MoS2-rGO hybrid architecture as durable support for cathode catalyst in proton exchange membrane fuel cells

Carbon black is utilized as a conventional electrocatalyst support material for proton exchange membrane fuel cells. However, this support is prone to corrosion under oxidative and harsh environments, thus limiting the durability of the fuel cells. Meanwhile, carbon corrosion would also weaken the linkage between Pt and the support material, which causes Pt agglomeration, and consequently, deterioration of the cell performance. To overcome the drawbacks of a Pt/C electrocatalyst, a hybrid support material comprising molybdenum disulfide and reduced graphene oxide is proposed and synthesized in this study to exploit the graphitic nature of graphene and the availability of the exposed edges of MoS2. TEM results show the uniform dispersion of Pt nanoparticles over the MoS2-rGO surface. Electrochemical measurements indicate higher ECSA retention and better ORR activity after 10000 potential cycles for Pt/MoS2-rGO as compared to Pt/C, demonstrating the improved durability for this hybrid support material.

Design and Fuel Consumption Optimization for a Bio-Inspired Semi-floating Hybrid Vehicle

Based on a bionic concept and combing air-cushion techniques and track driving mechanisms, a novel semi-floating hybrid concept vehicle is proposed to meet the transportation requirements on soft terrain. First, the vehicle scheme and its improved duel-spring flexible suspension design are described. Then, its fuel consumption model is proposed accordingly with respect to two vehicle operating parameters. Aiming at minimizing the fuel consumption, two Genetic Algorithms （GAs） are designed and implemented. For the initial one （GA-1）, despite getting an acceptable result, there still existed some problems in its optimiza- tion process. Based on an analysis of the defects of GA-1, an improved algorithm GA-2 was developed whose effectiveness and stability were embodied in the optimization process and results. The proposed design scheme and optimization approaches can provide valuable references for this new kind of vehicle with industry, military or scientific exploitations, etc. promising applications in the areas of agriculture, petroleum industry, military or scientific explaitations, etc.

Semiconductor,molecular and hybrid systems for photoelectrochemical solar fuel production

The paper shortly reviews the basic direct approaches applied in searching for viable solutions to solar fuel production. These are generally distinguished in molecular and semiconductor(non-molecular)systems, however, hybrid strategies, proposed recently, have also been included. The most promising efforts are considered, highlighting key aspects and emerging critical issues. Special attention is paid to aspects such as electrode architecture, device design, and main differences in the scientific vision and challenges to directly produce solar fuels. This overview could be useful to orientate the readers in the wide panorama of research activities concerning water splitting, natural and artificial photosynthesis, and solar fuel production through the identification of common aspects, specialties and potentialities of the many initiatives and approaches that are developing worldwide in this field with the final aim to meet world energy demand.

A novel supercapacitor-fuel cell hybrid cell

A monolithic hybrid fuel cell (MHFC) with a novel configuration was proposed in an effort to improve the fuel cell performance during instantaneous power changes. A modified direct methanol fuel cell (DMFC) with a layer of hydrous ruthenium dioxide (RuO2·xH2O) sandwiched between the anode catalyst layer and membrane was used to demonstrate the principle of the MHFC. Experimental results indicate that the RuO2·xH2O layer is equivalent to a resistor-capacitor transmission line and functions similar to a capacitor in parallel with the anode electrode. The improvement in dynamic response of the MHFC was experimentally confirmed under step current change and square current pulse operating. The ionic conductivity of the RuO2·xH2O layer was also obtained.

A comparative study of hybrid electric vehicle fuel consumption over diverse driving cycles

Environmental pollution and declining resources of fossil fuels in recent years,have increased demand for better fuel economy and less pollution for ground transportation.Among the alternative solutions provided by researchers in recent decades,hybrid electric vehicles consisted of an internal combustion engine and an electric motor have been considered as a promising solution in the short-term.In the present study,fuel economy characteristics of a parallel hybrid electric vehicle are investigated by using numerical simulation.The simulation methodology is based on a fast forward facing simulation model of a parallel hybrid and an internal combustion engine powertrains.The objective of this study is to present the main parameters which result in an optimum combination of hybrid powertrain components in order to obtain a better fuel economy of hybrid powertrains regarding different driven cycles and hybridization factors.Then,the fuel consumption of the parallel hybrid electric vehicles are compared considering various driven cycles and hybridization factors.The results showed that the better fuel economy of hybrid powertrains increases by decreasing average load of the test cycle and the point of the best fuel economy for a particular average load of the cycle moves towards higher hybridization factors when the average load of the test cycle is reduced.

Multi-objective comprehensive optimization of fuel consumption and emission for hybrid electric vehicles

Aiming to reduce fuel consumption and emissions of a dual-clutch hybrid electric vehicle during cold start, multiobjective optimization for fuel consumption and HC/CO emission from a TWC(three-way catalytic converter) outlet is presented in this paper. DP(dynamic programming) considering dual-state variables is proposed based on the Bellman optimality principle. Both the battery SOC(state of charge) and the temperature of TWC monolith are considered in the algorithm simultaneously. In this way the global optimal control strategy and the Pareto optimal solution of multi-objective function are derived. Simulation results show that the proposed method is able to promote the TWC light-off significantly by decreasing the engine's load and improving exhaust temperature from the outlet of the engine, in comparison with original DP considering the single battery SOC. Compared to the results achieved by rule-based control strategy, fuel economy and emission of TWC outlet for cold start are optimized comprehensively. Each indicator of Pareto solution set shows the significant improvement.

Effect of tree-age on calorific value and other fuel properties of Eucalyptus hybrid

For determining the effect of tree-age on the fuel properties of Eucalyptus hybrid, the variability in basic density, calorific value, proximate and ultimate parameters of 2-6 years old trees and mature trees （20- year-old）, grown under short rotation forestry regime, were measured and analyzed. Results show that there was no significant variation in the basic density of wood for 2-6 year-old Eucalyptus hybrid, with average value of 0.55-0.58 g.cm-3; the calorific value of mature trees was higher than that of lower age trees, but the ash content was much higher in lower age trees compared to mature trees. No particular trend was observed for volatile matter content and the fixed carbon content with tree-age. In conclusion, the fuel properties of mature tree were marginally better than trees of lower age.

A Novel Method for the Application of the ECMS(Equivalent Consumption Minimization Strategy)to Reduce Hydrogen Consumption in Fuel Cell Hybrid Electric Vehicles

Fuel cell hybrid electric vehicles are currently being considered as ideal means to solve the energy crisis and global warming in today’s society.In this context,this paper proposes a method to solve the problem related to the dependence of the so-called optimal equivalent factor(determined in the framework of the equivalent consumption minimum strategy-ECMS)on the working conditions.The simulation results show that under typical conditions(some representative cities being considered),the proposed strategy can maintain the power balance;for different initial battery’s states of charge(SOC),after the SOC stabilizes,the fuel consumption is 5.25 L/100 km.

Control system design of hybrid fuel cell city bus

This paper introduced the design of the hybrid powertrain of the Fuel Cell City Bus demonstrated in 2008 Beijing Olympic Games. The configuration of the hybrid fuel cell powertrain was introduced. The safety of hydrogen storage and delivery system, the hydrogen leakage alarm system were developed. The real-time distributed control and diagnosis system based on the Time Trigger Controller Area Network （TTCAN） with 10 ms basic control period was developed. The concept and implementation of processor （or controller） monitor and process （or task） monitor technique based on the TYCAN were applied in this paper. The fault tolerant control algorithm of the fuel cell engine and the battery man- agement system were considered. The demonstration experience verified that the fault tolerant control was very important for the fuel cell city bus.

Characterization of semi-coke generated by coal-based direct reduction process of siderite

Solid wastes derived from metallurgical industries pose a significant threat to environment. The utilization and disposal of these solid wastes are the major concern in the world. Semi-coke generated in coal-based direct reduction process of iron ore is a by-product and its suitable utilization is not available so far. In order to handle it properly, the characteristics of this by-product were comprehensively investigated. A series of analysis methods were used to demonstrate its mineral compositions, petrography and physico-chemical properties. The results reveal that the semi-coke has poor washability. The fixed carbon content of semi-coke reaches 76.11% and the gross calorific value is 28.10 MJ/kg, both of which are similar to those of traditional sinter coke breeze. Also, semi-coke ash possesses lower content of SiO2, Al2O3, S and higher content of CaO and MgO, which could improve the strength of sinter ore when partially substituting for coke breeze in sintering. Semi-coke features well-development porous structure and higher reaction activity, which predicts that the sintering speed could be elevated to some extent when employing it as a partial replacement of coke breeze, so the studies further suggest that the potential adverse effect of the high reactivity on sintering process could be weakened by adequately coarsening the semi-coke's particle size.

Evaluation of In-Use Fuel Economy for Hybrid and Regular Transit Buses

Fuel costs are a significant portion of transit agency budgets. Hybrid technology offers an attractive option and has the potential to significantly reduce operating costs for agencies. The main impetus behind use of hybrid transit vehicles is fuel savings and reduced emissions. Laboratory tests have indicated that hybrid transit buses can have significantly higher fuel economy and lower emissions compared to conventional transit buses. However, the number of studies is limited and laboratory tests may not represent actual driving conditions since in-use vehicle operation differs from laboratory test cycles. Several initial studies have suggested that the fuel economy savings reported in laboratory tests may not be realized on-road. The objective of the project described in this paper was to evaluate the in-use fuel economy differences between hybrid-electric and conventional transit buses for the Ames, Iowa (USA) transit authority. On-road fuel economy was evaluated over a 12-month period for 12 hybrid and 7 control transit buses. Fuel economy comparisons were also provided for several older in-use bus types. Buses other than the control and hybrid buses were grouped by model year corresponding to US diesel emission standards. Average fuel economy in miles per gallon was calculated for each bus group overall and by season. Hybrid buses had the highest fuel economy for all time periods for all bus types. Hybrid buses had a fuel economy that was 11.8% higher than control buses overall and was 12.2% higher than buses with model years 2007 and higher, 23.4% higher than model years 2004 to 2006, 10.2% higher than model years 1998 to 2003, 38.1% higher than for model years 1994 to 1997, 36.8% higher for model years 1991 to 1993, and 36.8% higher for model years pre-1991. Differences between groups of buses also varied by season of the year.

Reduced formation of peroxide and radical species stabilises iron-based hybrid catalysts in polymer electrolyte membrane fuel cells

The incorporation of Pt into an iron-nitrogen-carbon(Fe NC)catalyst for the oxygen reduction reaction(ORR)was recently shown to enhance catalyst stability without Pt directly contributing to the ORR activity.However,the mechanistic origin of this stabilisation remained obscure.It is established herein with rotating ring disc experiments that the side product,H_(2)O_(2),which is known to damage FeNC catalysts,is suppressed by the presence of Pt.The formation of reactive oxygen species is additionally inhibited,independent of intrinsic H_(2)O_(2) formation,as determined by electron paramagnetic resonance.Transmission electron microscopy identifies an oxidised Fe-rich layer covering the Pt particles,thus explaining the inactivity of the latter towards the ORR.These insights develop understanding of Fe NC degradation mechanisms during ORR catalysis,and crucially establish the required properties of a precious metal free protective catalyst to improve Fe NC stability in acidic media.

Hybrid Dynamic Modeling and Control of Molten Carbonate Fuel Cell Stack Shutdown

A hybrid automaton modeling approach that incorporates state space partitioning, phase dynamic modeling and control law synthesis by control strategy is utilized to develop a hybrid automaton model of molten carbonate fuel cell (MCFC) stack shutdown. The shutdown operation is divided into several phases and their boundaries are decided according to a control strategy, which is a set of specifications about the dynamics of MCFC stack during shutdown. According to the control strategy, the specification of increasing stack temperature is satisfied in a phase that can be modeled accurately. The model for phase that has complex dynamic is approximated. The duration of this kind of phase is decreased to minimize the error caused by model approximation.

New hybrid model of proton exchange membrane fuel cell

Model and simulation are good tools for design optimization of fuel cell systems. This paper proposes a new hybrid model of proton exchange membrane fuel cell (PEMFC). The hybrid model includes physical component and black-box com-ponent. The physical component represents the well-known part of PEMFC, while artificial neural network (ANN) component estimates the poorly known part of PEMFC. The ANN model can compensate the performance of the physical model. This hybrid model is implemented on Matlab/Simulink software. The hybrid model shows better accuracy than that of the physical model and ANN model. Simulation results suggest that the hybrid model can be used as a suitable and accurate model for PEMFC.

Hybrid dynamic model of polymer electrolyte membrane fuel cell stack using variable neural network

The polymer electrolyte membrane（PEM） fuel cell has been regarded as a potential alternative power source,and a model is necessary for its design,control and power management.A hybrid dynamic model of PEM fuel cell,which combines the advantages of mechanism model and black-box model,is proposed in this paper.To improve the performance,the static neural network and variable neural network are used to build the black-box model.The static neural network can significantly improve the static performance of the hybrid model,and the variable neural network makes the hybrid dynamic model predict the real PEM fuel cell behavior with required accuracy.Finally,the hybrid dynamic model is validated with a 500 W PEM fuel cell.The static and transient experiment results show that the hybrid dynamic model can predict the behavior of the fuel cell stack accurately and therefore can be effectively utilized in practical application.

Performance Evaluation of a Molten Carbonate Fuel Cell-Graphene Thermionic Converter-Thermally Regenerative Electrochemical Cycles Hybrid System

A combined system model is proposed including a molten carbonate fuel cell(MCFC),a graphene thermionic converter(GTIC)and thermally regenerative electrochemical cycles(TRECs).The expressions for power output,energy efficiency of the subsystems and the couple system are formulated by considering several irreversible losses.Energy conservation equations between the subsystems are achieved leaned on the first law of thermodynamics.The optimum operating ranges for the combined system are determined compared with the MCFC system.Results reveal that the peak power output density(POD)and the corresponding energy efficiency are 28.22%and 10.76%higher than that of the single MCFC system,respectively.The effects of five designing parameters on the power density and energy efficiency of the MCFC/GTIC/TRECs model are also investigated and discussed.

Evaluation of Fuel Cell Vehicle Regarding Hybridization Degree and Its Impact on Range, Weight and Energy Consumption

PUMA Mind is a co-funded project aimed at enhancing the understanding of the behavior of fuel cell systems in vehicles taking advantage of the new freedoms in design that electric powertrains provide. Within this project, IDIADA focused on the integration of fuel cell systems in the automotive sector and the resulting fuel cell power demand profiles were used as base line to develop the fuel cell technology within the scope of the project. This paper presents a further study on the PUMA Mind vehicles with the simulation software for Simulink environment vemSim developed at IDIADA. The paper deals with the sizing of a pure fuel cell vehicle, a hybrid fuel cell vehicle and a plug-in hybrid fuel cell vehicle. For each case, a dynamic vehicle model and an energy management algorithm were implemented in vemSim in order to calculate the required energy storage and optimize the powertrain efficiency and range in a variety of real driving conditions. Finally, simulations results were used to evaluate the impact of the hybridization degree on vehicle weight, components size, hydrogen and electric consumption and variability of the fuel cell and battery load. Those results unveil that all typologies of hybridization mentioned in the following paragraphs reach the target of range and obtain good performances according to different mission profiles.

Dual Pressure versus Hybrid Recuperation in an Integrated Solid Oxide Fuel Cell Cycle--Steam Cycle

A SOFC （solid oxide fuel cell） cycle running on natural gas was integrated with a ST （steam turbine） cycle. The fuel is desulfurized and pre-reformed before entering the SOFC. A burner was used to combust the remaining fuel after the SOFC stacks. The off-gases from the burner were used to produce steam in a HRSG （heat recovery steam generator）. The bottoming steam cycle was modeled with two configurations： （1） a simple single pressure level and （2） a dual pressure level with both a reheat and a pre-heater. The SOFC stacks in the present SOFC-ST hybrid cycles were not pressurized. The dual pressure configuration steam cycle combined with SOFC cycle （SOFC-ST） was new and has not been studied previously. In each of the configuration, a hybrid recuperator was used to recovery the remaining energy of the off-gases after the HRSG. Thus, four different plants system setups were compared to each other to reveal the most superior concept with respect to plant efficiency and power. It was found that in order to increase the plant efficiency considerably, it was enough to use a single pressure with a hybrid recuperator instead of a dual pressure Rankine cycle.