Electric vehicles are becoming more and more prevalent, especially with major manufacturers announcing that they will be focusing on electric or hybrid vehicles in the future. This article describes an object-oriented approach to a vehicle model using Python 3. This approach allows for flexibility of vehicle design. The key parameters were input to define the specific vehicle for validation, in this case a Nissan Leaf. It is anticipated that this flexibility will lead to rapid exploratory design of vehicle variants, such as four-wheel drive, independent wheel drive and multiple electrical sources. The model had its objects individually validated before the whole vehicle was verified against common drive cycles and a real-world drive in the United Kingdom recorded using an On-board Diagnostics (OBD2) Bluetooth dongle.

Alternative fuel vehicles, such as battery electric vehicles and hydrogen fuel cell vehicles, support the imperative to decarbonise the transport sector, but are not yet at a stage in their development where they can successfully compete with conventional fuel vehicles. This paper examines the influence of knowledge and persuasion on the decision to adopt or reject alternative fuel vehicles, a novel and original application of Rogers’ Theory of Diffusion of Innovations. A household questionnaire survey was undertaken with respondents in the Sutton Coldfield suburb of the United Kingdom city of Birmingham. This suburb was previously identified as having a strong spatial cluster of potential early adopters of alternative fuel vehicles. The survey results provide some useful empirical insights around the issues pertaining to the wider adoption of alternative fuel vehicles, even though the data is a bit dated as the survey was conducted in 2013. It is confirmed that respondents have limited knowledge of alternative fuel vehicles and perceptions have led to the development of negative attitudes towards them. The reasons largely relate to three problems: purchase price, limited range and poor infrastructure availability. Most respondents passively rejected alternative fuel vehicles, which confirms that a concerted effort is required to inform the general public about the benefits alternative fuel vehicles.

Ionic liquids are a natural choice for supercapacitor electrolytes. However, their cost is currently high. In the present work, we report the use of ternary mixtures of sulfolane, 3-methyl sulfolane, and quaternary ammonium salts (quats) as low-cost alternatives. Sulfolane was chosen because it has a high Hildebrand solubility parameter (delta(H) = 27.2 MPa1/2) and an exceptionally high dipole moment (mu = 4.7 D), which means that it mixes readily with ionic liquids. It also has a high flash point (165 degrees C), a high boiling point (285 degrees C), and a wide two-electrode (full-cell) voltage stability window (>7 V). The only problem is its high freezing point (27 degrees C). However, by using a eutectic mixture of sulfolane with 3-methyl sulfolane, we could depress the freezing point to -17 degrees C. A second goal of the present work was to increase the electrical conductivity of the electrolyte beyond its present-day value of 2.1 mS cm(-1) at 25 degrees C, currently provided by butyltrimethylammonium bis(trifluoromethylsulfonyl)imide (BTM-TFSI). We explored two methods of doing this: (1) mixing the ionic liquid with the sulfolane eutectic and (2) replacing the low-mobility TFSI anion with the high-mobility MTC anion (methanetricarbonitrile). At the optimum composition, the conductivity reached 12.2 mS cm(-1) at 25 degrees C.

Supercapacitors are an emerging technology with applications in pulse power, motive power, and energy storage. However, their carbon electrodes show a variety of non-ideal behaviours that have so far eluded explanation. These include Voltage Decay after charging, Voltage Rebound after discharging, and Dispersed Kinetics at long times. In the present work, we establish that a vertical ladder network of RC components can reproduce all these puzzling phenomena. Both software and hardware realizations of the network are described.In general, porous carbon electrodes contain random distributions of resistance R and capacitance C, with a wider spread of log R values than log C values. To understand what this implies, a simplified model is developed in which log R is treated as a Gaussian random variable while log C is treated as a constant. From this model, a new family of equivalent circuits is developed in which the continuous distribution of log R values is replaced by a discrete set of log R values drawn from a geometric series. We call these Pascal Equivalent Circuits. Their behaviour is shown to resemble closely that of real supercapacitors. The results confirm that distributions of RC time constants dominate the behaviour of real supercapacitors. (C) 2017 The Authors. Published by Elsevier B.V.

The Energy Management Strategy (EMS) of any hybrid vehicle is responsible for determining the operating state of many components on board the vehicle and therefore has significant effect on the fuel economy, emissions, ageing of components and vehicle drive-ability. It is generally accepted that Stochastic Dynamic Programming (SDP) can be used to produce a near-optimal control strategy provided that an accurate Markov model of the drive-cycle is available, and the cost function used for the optimisation is representative of the true running cost of the vehicle. The vast majority of research in this field focussing solely on the optimisation of the fuel economy, however for a fuel cell hybrid vehicle, the degradation of the fuel cell contributes significantly to the overall running cost of the vehicle, and should therefore be included in calculation of the running cost during the optimisation process. In this work, an optimised controller using SDP is developed for a campus passenger vehicle in order to minimise the lifetime cost of both fuel consumption and fuel cell degradation. The vehicle is then simulated over a number of typical journey's obtained from data logging during its use on the University of Birmingham's campus. It is shown that the expected lifetime cost due to fuel cell degradation massively outweighs the cost of the fuel consumed.

Despite having efficiencies higher than internal combustion engines, heat rejection from fuel cells remains challenging due to lower operating temperatures and reduced exhaust heat flow. This work details a full system simulation which is then used to compare a conventional liquid cooled fuel cell system to two types of evaporatively cooled fuel cell systems. Both steady state and transient operation are considered. Results show the radiator frontal area required to achieve thermal and water balance for an evaporatively cooled system with an aluminium condensing radiator is 27% less than a conventional liquid cooled system at 1.25 A/cm(2) steady state operation. The primary reason for the reduction is higher heat transfer coefficients in the condensing radiator due to phase change. It is also shown that the liquid water separation efficiency has a significant influence on the required radiator frontal area of the evaporatively cooled system. (C) 2016 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

Evaporative cooling through liquid water injection directly into the fuel cell flow channels removes the requirement for external humidification and liquid cooling channels within the stack. However, the amount of liquid water injected must be accurately controlled, to prevent on one hand membrane drying due to lack of water vapor and on the other hand flooding due to excessive liquid water.In this paper a one-dimensional, non-isothermal model of an evaporatively cooled proton exchange membrane fuel cell (PEMFC) is produced. The model accounts for changes in relative humidity and temperature along the anode and cathode flow channels, water transfer through the membrane and liquid accumulation within the gas diffusion layers. The model was used to study liquid water injection strategies at both cell and localized level. The influence of current density, operating pressure and inlet humidity were investigated. Results show that provided high humidity is maintained throughout the cell, exhaust gas temperature increase from low to high current densities (0.4-1.4A/cm(2)) is less than 4.0 degrees C, without the need for active temperature control. Furthermore both temperature regulation and good membrane hydration can be managed by uniform injection of liquid water throughout the cell to maintain a target cathode exhaust humidity.

Electrical and thermal conductivity models from Mamunya etal. and Kerner's equation for elastic and flexural modulus have been applied to experimental data to assess model accuracies. Experimental data were gained from a previous study where polyethylene and carbon black, graphite and magnetite composites produced by injection and compression moulding were tested. The electrical conductivity modelling gave accurate fits to the data, though available data were limited and the thermal conductivity modelling produced good fits with R-2 values greater than 0.93. The electrical and thermal model exponents were tuned for best fit and used to compare the modelling results with the literature and gain information about conduction mechanisms such as tunnelling and links, nodes and blobs and variations in local filler concentrations. A modified Kerner's equation to effectively allow for filler type and variations in composite processing was used to improve upon the original equation which modelled modulus behaviour based on the pure matrix. The new equation proved to be a better predictor of elastic modulus than flexural modulus.

Differentiating between the various polytetrafluoroethylene based structures inside polymer electrolyte membrane fuel cells with a degree of certainty is necessary to optimize manufacturing processes and to investigate possible degradation mechanisms. We have developed a novel method using fluorescence microscopy for distinguishing the origin and location of PTFE and/or Nafion® in Membrane Electrode assemblies and the gas diffusion media from different sources and stages of processing. Fluorescent material was successfully diffused into the PTFE based structures in the GDM by addition to the ‘ink’ precursor for both the microporous layer and the catalyst layer; this made it possible to map separately both layers in a way that has not been reported before. It was found that hot pressing of membrane coated structures resulted in physical dispersion of those layers away from the membrane into the GDM itself. This fluorescence technique should be of interest to membrane electrode assembly manufacturers and fuel cell developers and could be used to track the degradation of different PTFE structures independently in the future.

The cost and reliability of fuel cells are major obstructions preventing fuel cell hybrid electric vehicle (FCHEV) from entering the mainstream market. However, many of the degradation methods are strongly affected by the operating conditions of the fuel cell and therefore can be mitigated by optimisation of the Energy Management Strategy (EMS). The major causes of fuel cell degradation are identified from the literature and a model is produced in order to estimate the effect of the EMS on the fuel cell degradation. This is used to produce an optimal strategy for a low speed campus vehicle using Stochastic Dynamic Programming (SDP). The SDP controller attempts to minimise the total running cost of the fuel cell, inclusive of both fuel consumption and degradation, each weighted by their respective costs. The new strategy is shown to increase the lifetime of the fuel cell by 14%, with only a 3.5% increase in fuel consumption, largely by avoiding transient loading on the fuel cell stack.

Maintaining proton exchange membrane fuel cell (PEMFC) stack operating temperature across transient current profiles presents a significant challenge for fuel cell vehicles. Liquid cooled systems require active control of coolant temperature and flow rate to match heat rejection to heat generation. Evaporative cooling is an alternative to conventional liquid cooling in automotive sized PEMFC stacks. In an evaporatively cooled system, liquid water is injected directly into the cathode flow channels where it evaporates, both cooling and humidifying the stack. This paper uses a validated simulation to explore the inherent temperature regulation abilities of an evaporatively cooled PEMFC stack across a range of current profiles and drive cycles. Results show that throughout the normal operating current range, stack temperature varies by less than +/- 2.0 degrees C, this is comparable to liquid cooling but without the need for active temperature control. The introduction of variable operating pressure and cathode stoichiometry using proportional integral control, can further reduce temperature variation to +/- 1.0 degrees C and +/- 1.2 degrees C respectively for step increases in current demand. Variable operating pressure is also shown to improve warm up time and reduce heat loss at low operating loads. Copyright (C) 2015, The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications, LLC.

This paper explores how the operating pressure of an evaporatively cooled fuel cell influences the required radiator frontal area via the use of a fuel cell vehicle model with validated electrochemical and radiator subsystems. Results show an operating pressure increase of 0.6bar reduces required radiator frontal area by up to 30% at 25kW net electrical load due to elevated operating temperatures. The influence of vehicle speed and fan speed are studied, at 25kW net load, 0.2bar back pressure the vehicle would overheat below 20m/s, with 2000rpm fan speed sufficient cooling is obtained with a 0.2m(2) radiator area at all speeds.

The transport sector has been identified as a significant contributor to greenhouse gas emissions. As part of its emissions reduction strategy, the United Kingdom Government is demonstrating support for new vehicle technologies, paying attention, in particular, to electric vehicles.Cluster analysis was applied to Census data in order to identify potential alternative fuel vehicle drivers in the city of Birmingham, United Kingdom. The clustering was undertaken based on characteristics of age, income, car ownership, home ownership, socio-economic status and education. Almost 60% of areas that most closely fitted the profile of an alternative fuel vehicle driver were found to be located across four wards furthest from Birmingham city centre, while the areas with the poorest fit were located towards the centre of Birmingham. The paper demonstrates how Census data can be used in the initial stages of identifying potential early adopters of alternative vehicle drivers. It also shows how such research can provide scope for infrastructure planning and policy development for local and national authorities, while also providing useful marketing information to car manufacturers. (C) 2012 Elsevier Ltd. All rights reserved.

This paper presents the data recorded from two G-Wiz Reva electric vehicles (EVs) over a period of two years and approximately 8000 km on each vehicle. The analysis of the vehicle data demonstrates that the range of the vehicle obtained for a certain state-of-charge (SOC) drop was not consistent. The results show that the main factor affecting the available range was irregular vehicle usage. The recharge energy consumption patterns of the vehicle were identified and it was demonstrated that infrequent vehicle usage increased energy consumed by the vehicle. A maximum range of 66.8 km was achieved when the vehicle was regularly used, but this fell to 42.8 km when it was infrequently used. The energy economy when the vehicle was regularly used was 8.3 km/kWh. Additionally, the analysis results identify the need to determine discharge rate of the vehicle batteries to determine the precise effects on the available range and energy consumption of the vehicle.

Bipolar plates are the interconnects between cells within a fuel cell stack. They must be highly electrically conductive in order to maximize the voltage across the stack and must be highly thermally conductive to aid cooling of the stack. Traditionally, bipolar plates are made from graphite or stainless steel; both have drawbacks such as low mechanical strength and corrosion problems, respectively. In order to overcome the problems associated with these common materials and to improve on the electrical and thermal conductivity aspects as well as decrease costs and improve manufacturability, a mixture of polyethylene and carbon was investigated. Composites of polyethylene and carbon were mixed using a two-roll mill and injection moulded. Micrographs of the polyethylene-carbon (PE-C) blends show how the microstructure of the polyethylene network and carbon particles provide increased mechanical properties but further addition of carbon leads to the degradation of these properties. Increasing carbon content led to an ever-increasing electrical conductivity. The material was tested for tensile and flexural properties, resulting in a maximum tensile and flexural strength of ∼24 MPa (at 26 wt% carbon in polyethylene) and ∼35 MPa (at 40 wt% carbon in polyethylene), respectively. The samples displayed electrical conductivity, with a maximum of 1.19 S/cm in-plane and 1.05 S/cm through-plane being achieved at a carbon loading of 65 wt%. The PE-C composite displayed low densities of 1.56 g/cm3 and desirable mechanical strength close to the US Department of Energy target level of 44.26 MPa for flexural strength. It was concluded that PE-C composites with different types of carbon and carbon fibres should be tested in order to reach the electrical conductivity target levels of 100 S/cm.

Steady state and dynamic models of proton exchange membrane fuel cell (PEMFC) or solid polymer fuel cell (SPFC) systems have been developed for transport and stationary applications. This paper reports the results of a steady state analysis of a methanol-fuelled PEMFC vehicle with a maximum (electrical) power output of 50 kW. The model incorporates a methanol steam reformer, gas clean-up unit, fuel cell stack, compressor, expander, battery pack, and heat exchangers as well as electrical power handling, motor, gearbox, and final drive. Results are given for the reformer as a function of steam-carbon ratio and reformer temperature. A degree of optimization of the system was conducted by (a) the addition of preheat to the reformer and burner reactants and (b) the addition of condensers for the fuel cell exhaust gases. The effect of operating pressure was also investigated. It was concluded that only by proper thermal integration could the target electrical system efficiency of better than 45 per cent at rated power be achieved.