0000000000131582
AUTHOR
Peter Hugh Middleton
Performance Analysis of Single Cell Alkaline Electrolyser Using Mathematical Model
Abstract The generation of hydrogen using electrolysis process with integrated renewable energy sources is very important specially in environmental aspects. In this paper, we demonstrate that, the performance of electrolysis process which could be enhanced by decreasing the distance between electrodes while changing the properties of electrodes. At first, two single cell alkaline electrolysers are fabricated using an in-house 3D printer. Thereafter, the best performing cell is selected by considering its performance through different experiments. Finally, the performance of the selected cell is analysed by changing the distance between electrodes and changing the properties of electrodes. …
Long term stability testing of oxide unicouple thermoelectric modules
Thermoelectric devices based on oxides are good candidates for energy harvesting technologies for use in aggressive conditions where the materials should withstand high temperatures and corrosive environments over prolonged time. This leads to a natural concern for the stability of the electrical contacts, especially on the hot side of the module. In this work, we have assembled several prototype unicouple thermoelectric modules made by pyrolyzed and spark plasma sintered n-type CaMnO3 and p-type Ca3Co4O9 and then tested under different conditions mimicking end-user applications. For baseline experiments we have chosen to use nickel as the contact material in order to show the effect of its…
Review of gas diffusion cathodes for alkaline fuel cells
Abstract This paper gives a technical background to alkaline fuel cells (AFCs), introducing the advantages and drawbacks of the technology. AFCs offer the potential for low cost, mass producible fuel cells, without the dependency on platinum based catalysts and (currently) expensive membrane electrolytes. The AFC uses relatively low cost electrolytes based on aqueous bases such as potassium hydroxide. The inherent CO 2 sensitivity of the electrolyte can be addressed by filtering out the CO 2 from the air intake using a simple scrubber and periodically replacing the liquid electrolyte. A review of the state-of-the-art in gas diffusion cathode development is given. The overall cell performanc…
A new application for nickel foam in alkaline fuel cells
The use of nickel foam as an electrode substrate in alkaline fuel cells (AFCs) has been investigated for bi-polar cells incorporating an electrically conducting gas diffusion layer. This contribution focuses on the cathode, and draws comparisons between nickel foam and nickel mesh substrates. One of the principal electrocatalysts for the cathodic reduction of oxygen is silver, so an improvement in electrochemical performance was obtained by electroplating the nickel foam with silver. The electrodeposition process was optimised to maximise electrochemical performance with a minimum of silver deposited. Nickel foam, which is less expensive than the usual nickel mesh, appears to be a good subs…
Alkaline fuel cell technology - A review
Abstract The realm of alkaline-based fuel cells has with the arrival of anionic exchange membrane fuel cells (AEMFCs) taken a great step to replace traditional liquid electrolyte alkaline fuel cells (AFCs). The following review summarises progress, bottleneck issues and highlights the most recent research trends within the field. The activity of alkaline catalyst materials has greatly advanced, however achieving long-term stability remains a challenge. Great AEMFC performances are reported, though these are generally obtained through the employment of platinum group metals (PGMs), thus emphasising the importance of R&D related to non-PGM materials. Thorough design strategies must be utilise…
High temperature oxidation of higher manganese silicides
Abstract The oxidation kinetics and mechanisms of higher manganese silicides (HMS) MnSi1.75, MnSi (1.75-x)Gex, MnSi(1.75-x)Alx (with x = 0.005 and 0.01)were studied and the effects of densification methods and dopant concentration discussed. Oxidation experiments were conducted using thermogravimetry (TGA), while post characterization with X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscope (SEM) showed that spark plasma sintering (SPS) is a better densification method than hot pressing (HP). Except for undoped HMS, HMS doped with 0.5at% Ge had the lowest oxidation rate. Stable formation of a SiO2 protective layer was the main reason for improved oxidation resistance in …
Performance evaluation and stability of silicide-based thermoelectric modules
Abstract Long-term studies on thermoelectric generators based on N-type magnesium silicide (Mg2.01Si0.49Sn0.5Sb0.01) and P-type higher manganese silicide (Mn0.98Mo0.02Si1.73Ge0.02) materials are presented, in the operating temperature range of 200 °C–400 °C. Emphasis is put on the performance and reliability of the current collector configuration, especially on the hot side of the module, and on the thermomechanical stresses that are created during operation and lifetime testing as a result of large temperature gradients experienced across the thermoelectric legs. With silver (Ag) paste as contact material, the long term-stability of the uni-couples was carried out on non-metalized legs and…
Performance Analysis of Ammonia in Solid Oxide Fuel Cells
The transition of the marine propulsion system towards alternative fuels is mandatory to offset carbon emission. Among the alternative fuels, ammonia is carbon-free and can be produced in sustainable ways. Ammonia has 17.8% hydrogen (wt %) and is easily liquified at 25°C and 8 bar pressure. The two-stroke internal combustion engines currently used in the marine sector reach efficiencies of about 50% but generate substantial polluting emissions. Solid oxide fuel cells generate electricity with efficiencies greater than 50 % and can use ammonia as fuel. In this work, a single-cell SOFC was characterised using in-situ ammonia decomposition reaction (Int-ADR) and compared with ex-situ ammonia …
The effect of Mo and Ge reactive elements on high-temperature oxidation of higher manganese silicide
Abstract Higher manganese silicide (HMS) alloys (Mnx-αMoαSiy-βGeβ (x = 0.99–1.011, α = 0.005–0.02, y = 1.75, β = 0.005–0.01)) were studied to elucidate the effect of Mo and Ge pertaining to oxidation. Oxidation experiments were conducted using thermogravimetry and characterized using x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Isoconversion experiments below 450 °C, shows that doping (up to 2 at%) raises the oxidation potential of HMS. Isothermally, the oxidation rate reduces buy one order of magnitude by doping on Mn and/or Si sites from 0.5 to 2 at%, revealing that the dopants-based oxides do not lessen the robustness of SiO2 oxide.
Review of the Hydrogen Evolution Reaction—A Basic Approach
An increasing emphasis on energy storage has resulted in a surge of R&D efforts into producing catalyst materials for the hydrogen evolution reaction (HER) with emphasis on decreasing the usage of platinum group metals (PGMs). Alkaline water electrolysis holds promise for satisfying future energy storage demands, however the intrinsic potential of this technology is impeded by sluggish reaction kinetics. Here, we summarize the latest efforts within alkaline HER electrocatalyst design, where these efforts are divided between three catalyst design strategies inspired by the three prevailing theories describing the pH-dependence of the HER activity. Modifying the electronic structure of a …
An improved cathode for alkaline fuel cells
Abstract The use of nickel foam as an electrode substrate in alkaline fuel cells (AFCs) has been investigated for bipolar cells incorporating an electrically conducting gas diffusion layer (GDL). Improved performance, compared to a previous design, was obtained by adding an extra active layer (AL) composed of manganese (IV) oxide (MnO2) deposited onto carbon black. This new cathode design performed significantly better (130 mA cm−2 at 0.8 V and 25 °C) than the previous design (35 mA cm−2 under the same condition), especially at higher potential. It has been shown that the GDL is a key component of the gas diffusion electrode for both performance and durability, especially with liquid electr…
Experimental analysis of materials in proton exchange membrane electrolysis cells
Abstract An accelerated supply and demand of energy has resulted in an increased need for efficient energy storage options, where storing energy in hydrogen gas emerges as one of the most attractive. In this study, a singular proton exchange membrane (PEM) electrolysis cell was designed using adequately low-cost materials, and tested using polarisation curves, cyclic voltammetry and AC impedance. A comparative study of various micro porous layer (MPL) materials was performed in an effort to find suitable options which are able to steadily operate under anodic conditions. The best performance was achieved using carbon cloth, however this material was unstable. Untreated porous titanium and n…
PEM FC Single Cell Based on a 3-D Printed Plastic Housing and Experimental Validation with the Mathematical Model
Abstract This paper presents the design, modelling, and testing of a PEM single fuel cell based on the use of 3D printing. The design of the housings was made of SolidWorks, while MATLAB/SIMULINK were used to model performance. The fabricated cell performed satisfactorily with no leaks of gas, showing that the 3D printing method can be used in the additive manufacturing of fuel cells thus leading to significant cost savings.
Modelling of single cell solid oxide fuel cells using COMSOL multiphysics
Solid oxide fuel cells (SOFCs) have the potential to become one of the efficient and cost effective systems for direct conversion of a wide variety of fuels to electricity. In this study, we developed a three-dimensional multiphysics model for a single cell SOFC using COMSOL multiphysics (version 5.2) software and performed simulations to examine the effect of gas flow patterns (radial flow and counter flow) in different operating temperatures (700° C, 800° C and 1000° C) for a planar anode supported SOFC. With the help of the simulation results, we have analyzed the electrical characteristics of the single cell SOFCs. From the simulation results, it is observable that the radial gas flow p…
Performance analysis of single cell solid oxide fuel cells
Solid oxide fuel cells (SOFCs) are a class of fuel cells operating on high temperatures which have the potential to become one of the efficient and cost effective system for direct conversion of a wide variety of fuels to electricity. For proper operation of SOFCs, evaluation of cell stability and optimization of fuel utilization is of paramount importance. In this paper, we have performed experiments to obtain current-voltage (I–V) characteristics by using three different Hydrogen (H 2 ) flow rates(100 ml/min, 150 ml/min and 200 ml/min). Furthermore, we perform oxidation and reduction (redox) cycles to determine how many redox cycles a SOFC can withstand without cracking the cell which we …
Performance comparison of mono-polar and bi-polar configurations of alkaline electrolysis stack through 3-D modelling and experimental fabrication
Abstract Generation of hydrogen using electrolysis process with integrated renewable energy sources is highly important especially in environmental aspects. In this paper, we demonstrate that the enhancement of electrolysis performance of alkaline electrolysis stacks by diminishing the distance between electrodes, while changing the properties of the Membrane Electrode Assembly (MEA). Prior to that, the performances of mono-polar and bi-polar configurations of alkaline electrolysis stack are compared through 3-D modelling and experimental fabrication. At first, two different single cell alkaline electrolysers are designed using SolidWorks as a design software and the designed cell has been …