• Energy Research

In a green future, Fuel cells will probably become the suitable environmental friendly technology to generate power for several applications. They, in fact, generate electricity by an electrochemical process; in particular, Polymer Electrolyte fuel cells (PEMFC) use hydrogen and air as reactants, in combination with a solid, proton conductor electrolyte. Due to the complexity of the phenomena that take place inside a PEM fuel cell, scientists have focused their attention on different points, from the electrochemistry towards the fluid dynamics to mechanics. As well as the electrochemical components play a key role in the performance of a fuel cell, the distribution of the reactants over the electrode surfaces is fundamental for an optimal operation of the device. To understand PEMFC systems, a detailed analysis of the influence of main parameters on its performance and the development of different in situ analytical methods is fundamental. Segmented current collector (SCC) have proven to be an excellent in situ diagnostic tool, to a deep understanding on how a fuel cell works and to study the factors influencing the uneven electrochemical response of the Membrane Electrode Assembly (MEA). A SCC is similar to an ordinary fuel cell current collector with the exception that it is divided into smaller ones that can be individually interrogated for current, voltage and temperature.

In this work, a new family of zeolite coatings and an innovative heat exchanger concept are presented. Zeolite SAPO-34 coatings have been prepared and deposited on high-density graphite plates to investigate the feasibility of a new concept of adsorber for adsorption chillers. Different coating formulations have been prepared and characterized. Results demonstrated that SAPO-34 coatings maintain the characteristic adsorption properties of the native zeolite, develop an optimum bonding to the graphite plates and make it possible to improve the coating process for a better control of the layer thickness, in order to obtain different values of the final zeolite/support mass ratio. Finally, the schematic of an innovative graphite exchanger for heat pumps and chillers is provided. A bonded plate configuration have been adopted to remove bulky and heavy components such as the clamping plates. To this end experimental work have been conducted to address the suitable adhesive foe bonding the heat exchanger plates. The external shapes have been designed on the basis of the characterizations performed on small-scale samples, whereas inner fluid paths (heat transfer fluid side) have been developed by using Computational Fluid Dynamics in order to enhance heat transfer rate and temperature uniformity on the plate surface. Further, the main components of a full scale advanced exchanger has been showed and described. © 2014 Elsevier Ltd. All rights reserved.

The focus of this chapter is the design of a direct methanol fuel cell (FC) (DMFC) stack. In particular, the design of bipolar plates will be addressed and the reader will be able to build his own FC stack and design bipolar plates based on the desired performance. The discussion will be intentionally inspired by simplicity and intends to provide immediately usable tools and solutions, which are based on the direct experience of the authors [110]. The trip into the word of DMFC stack design starts from some recalls of thermodynamics and electrochemical, which are fundamental for choosing the operation point of the FC stack and the calculation of the flow rate of the reactants. Once the flow rates are known, the architecture of the FC stack can be defined, on the basis on the application, and the rest of FC stack components can be designed. This chapter covers the DMFC stack design principles, including stack architecture, reactants distribution, heat management, and stack clamping. The chapter aims to provide some useful guidelines to optimize the DMFC stack design and performance, a topic less covered in FC literature. In the following discussion, if not explicitly indicated, the sign of all numerical values is to be considered positive.

Hydrogen leakage in Proton Exchange Membrane (PEM) fuel cells poses critical safety, efficiency, and operational reliability risks. This study introduces an innovative infrared (IR) thermography-based methodology for detecting and quantifying hydrogen leaks towards the outside of PEM fuel cells. The proposed method leverages the catalytic properties of a membrane electrode assembly (MEA) as an active thermal tracer, facilitating real-time visualisation and assessment of hydrogen leaks. Experimental tests were conducted on a single-cell PEM fuel cell equipped with intact and defective gaskets to evaluate the method’s effectiveness. Results indicate that the active tracer generates distinct thermal signatures proportional to the leakage rate, overcoming the limitations of hydrogen’s low IR emissivity. Comparative analysis with passive tracers and baseline configurations highlights the active tracer-based approach’s superior positional accuracy and sensitivity. Additionally, the method aligns detected thermal anomalies with defect locations, validated through pressure distribution maps. This novel, non-invasive technique offers precise, reliable, and scalable solutions for hydrogen leak detection, making it suitable for dynamic operational environments and industrial applications. The findings significantly advance hydrogen’s safety diagnostics, supporting the broader adoption of hydrogen-based energy systems.

In this work a single cell testing procedure addressed to reproducibility and reliability of results is described. A Detailed description of the adopted criteria of fuel cell assembling, leakage test, cell conditioning, polarisation curve and stability test is reported. Particularly, attention has been focused at polarisation data acquisition algorithm aimed at experimental time reduction without affecting data quality. It is expected that results of this study might serve as a template which can be adapted and applied in the context of data exchange or joint testing between fuel cell developers and component suppliers.

Fuel cell technology development is one of the main activities at the CNR-TAE Institute. The matured experience on polymer electrolyte fuel cells (PEFC), especially on electrodes evolution, optimisation and characterisation of membrane-electrodes assemblies (MEAs) and new membrane research, has provided the opportunity to start with a project addressed to the realization of a small size PEFC stack. The first goal of this work was the development of a 100 W stack prototype based on low Pt loading electrodes evolved at CNR-ITAE and working at low pressure. This work reports our experience on stack evolution and performance obtained using H2/air as fuel and oxidant, respectively. The stack with 50 cm2 cells size was designed to produce a rated power of 100 W and a potential of 6 V. MEAs with a total Pt loading of 0.5 mg/cm2 and Nafion® 115 membranes were used. Humidifying conditions for fuel and oxidant based on water amount were studied at a working temperature of 80°C. The experimental activity was finalized to study the optimal operative conditions as a function of gases flux and water amount at 1.5 abs bar for both fuel and oxidant. A monitoring system of several parameters for each cell was a valid help to associate the stack failure with reagent management problems.

A polymer electrolyte fuel cell stack of 2 kW of peak power has been designed, manufactured and tested. Such a fuel cell stack has been envisaged to be applied for manned lunar exploration missions, as secondary energy source for both mobile vehicles and fixed power plants. The stack has been bread-boarded in order to test and demonstrate the technology. The following constraints have been considered during the study: (i) operation with pure hydrogen and oxygen (ii) low humidification levels (iii) use of commercial Membrane Electrode Assemblies. The breadboard has been made consisting of two modules, each of 500 W of nominal power. Specific tests have been conducted to prove the effect of gravity on the breadboard performance and verify its ability to follow variable load profiles over time, representative of different lunar surface exploration missions. The breadboard has shown a good performance during the test campaign, even if some failures of the Membrane Electrode Assemblies have been observed. The study has demonstrated the high performance of the developed stack and the potential of fuel cell technology for use in future human lunar exploration missions. At the same time, it has highlighted serious criticalities related to the reliability and robustness of the commercially available Membrane Electrode Assemblies, which need to be investigated further, before the use of this technology in a real space exploration mission can be possible.

Generating electric power using hydrogen is becoming a real hope; thanks to hydrogen technologies, climate challenges might be overcame and our towns would be free of pollutants and noise. For this reason, research and development of hydrogen technologies are fundamental to accelerate their introduction on the market as soon as possible. Starting from the electrochemical process, that allow electricity production, research activity has to be addressed to the design of fuel cell, which is the device "containing" the electrochemical package. In this field, namely in fuel cell stack research, the authors have developed a reliable methodology for stack design and test, over 15 years of experience. Prototyping is the direct expression of the research activity, carried out on the device, which allow the lab scale technology to be transferred on the real use. Due to that, research on fuel cells started studying the design methodology, has passed through the manufacture of the devices, until to experimental tests. In this way the issues related to the fuel cell stack "structure" can be highlighted and both the design methodology and, consequently, the manufacturing, improved. In this work, the authors illustrates how prototyping activity on fuel cell stack permitted the manufacturing of several prototypes, conceived for different applications (stationary, space, cogeneration in combination with reformer). Moreover, the improving in power and reliability of the devices and the problems encountered during research activities will be discussed.

Reactants distribution over the active area plays a key role in the performance of PEM fuel cell. The flow path that is designed to uniformly distribute fuel and oxidant over the active area, has also to respect some geometrical constraints such as the active area shape. Serpentine layout has been proven as efficient design especially at cathode, due to the fluid motion established in the flow field. A convective flow through the gas diffusion layer, also called cross flow, has been demonstrated to be responsible for a better PEM fuel cell performance using serpentine flow channels. As highlighted in previous studies the intensity of the cross flow is affected by several parameters, such as the thickness and permeability of the gas diffusion layer and the serpentine path length, even though the correlation between the cross flow intensity and the fuel cell active area shape factor (MEA width/height) has never explored before. In this work a numerical and experimental study has been carried out to investigate the effect of the active area shape factor on the cross flow intensity and its effect on the fuel cell performance. Three-dimensional CFD simulation, including electrochemical aspects, has been performed for two different serpentine flow paths extending over the same active area but different in shape factor. The effect of reactants stoichiometry and humidification on the fuel cell performance have been also envisaged. Numerical computations has shown that cross over flow intensity is higher in the flow field with the lowest area shape factor. In terms of electrochemical performance, this flow field operates better at higher current density because the high intensity of cross flow enhances reactants concentration and improves water removal from the gas diffusion layer. Experimental tests have also been performed for a comparison with numerical results.