Modelling and simulation of Proton Exchange Membrane fuel cell with serpentine bipolar plate using MATLAB

This report presents experimental results derived from a Proton Exchange Membrane fuel cell with a serpentine flow plate design. The investigation seeks to explore the effects of some parameters like cell operational temperature, humidification and atmospheric pressure on the general performance and efficiency of PEM fuel cell using MATLAB. A number of codes were written to generate the polarization curve for a single stack and five (5) cell stack fuel cell at various operating conditions. Detailed information of hydrogen and oxygen consumption and the effect they have on the fuel cell performance were critically analysed. The investigation concluded that the open circuit voltage generated was less than the theoretical voltage predicted in the literature. It was also noticed that an increase in current or current density reduced the voltage derived from the fuel cell stack. The experiment also clearly confirmed that when more current is being drawn from the fuel cell, more water will also be generated at the cathode section of the cell hence the need for an effective water management to improve the performance of the fuel cell. Other parameters like the stack efficiency and power density were also analysed using the experimental results obtained.     

A dynamic mechanical thermal analysis study of the viscoelastic properties and glass transition temperature behaviour of bioresorbable polymer matrix nanocomposites

The application of bioresorbable polymer nanocomposites in orthopaedics offer the potential to address several of the limitations associated with the use of metallic implants. Their enhanced biological performance has been demonstrated recently, but until now relatively little work has been reported on their mechanical properties. To this end, the viscoelastic properties and T_g of bioresorbable polylactide-co-glycolide/α-tricalcium phosphate nanocomposites were investigated by dynamic mechanical thermal analysis. At room temperature of approximately 20°C, the storage moduli of the nanocomposites were generally higher than the storage modulus of the unfilled polymer due to the stiffening effect of the nano-particles. However at physiological temperature of approximately 37°C, the storage moduli of the nanocomposites decreased from 6.2 to 15.4% v/v nano-particle loadings. Similarly the T_g of the nanocomposites also decreased from 6.2 to 15.4% v/v nano-particle loadings. These effects were thought to be due to weak interfacial bonding between the nano-particles and polymer matrix. The storage moduli at 37°C and T_g increased from the minimum value when the particle loading was raised to 25.7 and 34.2% v/v loadings. SEM and particle size distribution histograms showed that at these loadings, there was a broad particle size distribution consisting of nano-particles and micro-particles and that some particle agglomeration was present. The consequent reduction in the interfacial area and the number of weak interfaces presumably accounts for the rise in the storage modulus at 37°C and the T_g.     

Effect of fibre concentration, strain rate and weldline on mechanical properties of injection-moulded short glass fibre reinforced thermoplastic polyurethane

The effect of fibre concentration, strain rate and weldline on tensile strength, tensile modulus and fracture toughness of injection-moulded thermoplastic polyurethane (TPU) reinforced with different concentration levels of short glass fibres was investigated. It was found that tensile strength, σ_c, of single-gated mouldings increased with increasing volume fraction of fibres, ϕ_f, according to a second order polynomial function of the form and increased linearly with natural logarithm of strain rate (). Tensile modulus and fracture toughness (at initiation) of single-gated mouldings increased linearly with increasing ϕ_f (rule-of-mixtures) and . A linear dependence was obtained between fibre efficiency parameter for composite modulus, η_E, and . The presence of weldline in double-gated mouldings reduced tensile strength, tensile modulus and fracture toughness of TPU composites but had no significant effect upon properties of the TPU matrix. All the aforementioned properties increased with increasing fibre concentration and showed a linear dependence with respect to . Weldline integrity factor for all three properties decreased with increasing fibre concentration showing no strain-rate effect of any significance. Results indicated that tensile strength was more affected by the presence of weldline than tensile modulus or fracture toughness. It was noted that composite properties in the presence of weldline were still much greater than those for the unweld matrix. Weldline integrity values close to unity indicated that measured properties for the matrix were not significantly affected by the weldline.     

Development of Bi-polar plate design of PEM fuel cell using CFD techniques

This paper reviews the common existing designs of flow plates of fuel cells and suggests modifications to some of them to help reduce the pressure drop in the flow channels. Pressure drop is one of the factors that influence the overall performance of the cell both directly and indirectly through interaction with other factors including water management in the cell.The work uses computational fluid dynamics (CFD) to examine different design and study the effect of varying the flow rate (i.e. velocity) on the pressure drop for each of the designs modelled. Again, the designs are optimized by changing different parameters using ANSYS CFX. Results showing the effects of the modifications on pressure drop in the various plates are presented in this paper.From the study of the various designs, a conclusion was drawn that a modification of fuel cell designs in existence using a system similar to the diesel injection system design approach reduced the pressure drop in the fuel cell as shown by the simulation results.This reduction in pressure drop will contribute to the improvement of performance but it must be stressed that other factors also contribute to the overall performance of the cell and reduction in pressure drop alone is not a guarantee of better performance of a certain fuel cell design.     

Proton exchange membrane fuel cell performance prediction using artificial neural network

Polarization curves remain one of the parameters used to check the performance of fuels in terms of efficiency and durability. This investigation explores the application of artificial neutral network (ANN) to determine the voltage and current from a proton exchange membrane fuel cell having membrane area of 11.46 cm². Performance predictability for the group method of data handling (GMDH) as well as feed forward back propagation (FFBP) neutral networks were employed for the estimation of the current and voltage obtained from the Proton Exchange Membrane Fuel cell under investigation. The investigation presented models with good predictions even though GMDH neural network performed better than the FFBP neural network. The study therefore proposes the GMDH neural network as the best model for predicting the performance of a Proton Exchange Membrane Fuel cell. It was further deduced that an increase in reactant flow rate has direct effect on the performance of the fuel cell but this is directly proportional to the total irreversibilities in the cell hence to operate fuel cell economically, it is imperative that the hydrogen flow is made lower compare to the oxygen flow rate. This in effect will reduce the pumping power required for the flow of the fuel hence reducing the net loss in the cell.     

Performance evaluation of an air breathing polymer electrolyte membrane (PEM) fuel cell in harsh environments – A case study under Saudi Arabia's ambient condition

A key parameter that determines the efficiency of proton exchange membrane fuel cells is their operating conditions. Optimization of various components in these fuel cells is pivotal in improving cell performance, as their performance is directly related to the operational conditions the cells are subjected to.This investigation examined the viability of an air breathing fuel cell subjected to ambient conditions in Riyadh in Saudi Arabia. A validated three-dimensional air breathing 5-cell stack, modelled in ANSYS was utilised to generate the results. Furthermore, the work also considered the feasibility of deploying a humidifier unit for the hydrogen inlet, so as to ascertain the physical behaviour of the PEMFC stack. It was observed that the performance of the stack reaches its peak during the summer time (June–August), and hydrogen humidification improves output performance by 40%.     

Developments of electric cars and fuel cell hydrogen electric cars

The world continues to strive in the search for clean power sources to run the millions of different vehicles on the road on daily basis as they are the main contributors to toxic emissions releases from internal combustion engines to the atmosphere. These toxic emissions contribute to climate change and air pollution and impact negatively on people's health. Fuel cell devices are gradually replacing the internal combustion engines in the transport industry. Some notable challenges of the PEMFC technology are discussed in this paper. High costs, low durability and hydrogen storage problems are some of the major obstacles being examined in this investigation.The paper explores the latest advances in electric cars technology and their design specifications. The study also compares the characteristics and the technologies of the three types of electric cars now available in the market.     

A comparison on the dynamical performance of a proton exchange membrane fuel cell (PEMFC) with traditional serpentine and an open pore cellular foam material flow channel

Minimising the pressure drop in flow channels, ensuring high efficiency and utilisation of open pore cellular foam (OPCF) material in place of a traditional serpentine channel are investigated in this work. The paper establishes novel mathematical model that takes into account the effect of pressure drop in the flow channel and compares the dynamics of a porous flow channel with those of the traditional serpentine flow channel. The performance of a Polymer Electrolyte Membrane fuel cell with porous foam flow channel is analysed under static and transient conditions. The fuel cell mass transport equations are used in the model that also takes into account the effect of varying the current on the stack temperature. The membrane water content and IV-curves are analysed and simulation results are presented based on the mathematical models of the proposed system using the MATLAB®/Simulink® environments. The effect of varying pore diameter, porosity, and the flow velocity on pressure drop are also investigated using sensitivity analysis. Due to the lower pressure drop provided by the uniform distribution of reactants in OPCF channel, an improvement of approximately 55% is observed in current density when compared with that of the serpentine channel under the same operating conditions. The investigation further concluded that a higher pore diameter can have a lower drop in pressure provided the flow velocity of the reactant does not exceed 6 m/s.     

Transition metal carbides and nitrides as oxygen reduction reaction catalyst or catalyst support in proton exchange membrane fuel cells (PEMFCs)

Fuel cells are potentially efficient, silent, and environmentally friendly tools for electrical power generation. One of the obstacles facing the development and the commercialization of fuel cells is the dependence on the precious metal catalyst, i.e., Platinum (Pt) and Pt - alloy, especially at the cathode where high catalyst loading used to compensate the sluggish oxygen reduction reaction (ORR). Pt is not only an expensive and rare element but also has insufficient durability. The development of an efficient non-precious catalyst, i.e., electrochemically active, chemically and mechanically stable, and electrically conductive, is one of the basic requirements for the commercialization of fuel cells. The bonding to carbon and nitrogen to form metal carbides and nitrides modify the nature of the d-band of the parent metal, thus improve its catalytic properties relative to the parent metals to be similar to those of group VIII noble metals. In this article, we summarize the progress in the development of the transition metal carbides (TMCs) and transition metals nitrides (TMNs) relative to their application as catalysts for the ORR in fuel cells. The preparation of TMCs and TMNs via different routes which significantly affects its activity is discussed. The ORR catalytic activity of the TMCs and TMNs as a non-precious catalyst or catalyst support in fuel cells is discussed and compared to that of the Pt-based catalyst in this review article. Moreover, the recent progress in the preparation of the nano-sized (which is a critical factor for increasing the activity at low temperature) TMCs and TMNs are discussed.     

The influence of hydroxyapatite (HA) microparticles (m) and nanoparticles (n) on the thermal and dynamic mechanical properties of poly-l-lactide

In this paper, we explore the effects of hydroxyapatite microparticles and nanoparticles on the thermal and dynamic mechanical properties of injection moulded bioresorbable poly-l-lactide/hydroxyapatite composites intended for use in orthopaedics. The T_g of the nanocomposites were lower than those of the microcomposites. This was thought to be due to the larger surface area of well dispersed nanoparticles in the polymer matrix, leading to a larger interfacial area. The as-moulded composites were largely amorphous, however, during thermal analysis the polymer in the nanocomposites crystallized more and had lower cold crystallization temperature than that in the microcomposites since the nanoparticles acted as more effective nucleating agents. The storage moduli at 37 °C of the nanocomposites were higher than those of the microcomposites. The storage moduli of the composites approached the lower range of storage modulus for cortical bone and may prevent stress shielding during bone regeneration.