Elio Jannelli

Assessment of Fuel Cell Performance Under Different Air Stoichiometries and Fuel Composition

The behavior of fuel cells (FCs) at steady state and during transients is an important factor both for control tuning and for performance assessment. In the technical literature, few papers deal systematically with FC characterization. In this paper, the performance characterization of a proton exchange membrane (PEM) FC is carried out using an experimental analysis. The experimental activity has been conducted in a test station, properly designed and able to test PEM FC stacks in the range of 500-2000 W. The laboratory test facility is equipped with a National Instruments CompactDAQ real-time data acquisition and control system running a LabVIEW software. The bench commands two mass flow controllers, regulating both fuel flow and air flow which are commanded via two Recommended Standard 232 ports. The temperature of the FC is regulated via a fan operated by a brushless motor drive. An electronic load is connected to the FC terminals. The main operating parameters, such as the air stoichiometric ratio and fuel composition, have been varied and measured, and their influence on the PEM FC behavior has been investigated under both steady-state and transient conditions.

Lattice Boltzmann modeling of water entry problems

This paper deals with the simulation of water entry problems using the lattice Boltzmann method (LBM). The dynamics of the free surface is treated through the mass and momentum fluxes across the interface cells. A bounce-back boundary condition is utilized to model the contact between the fluid and the moving object. The method is implemented for the analysis of a two-dimensional flow physics produced by a symmetric wedge entering vertically a weakly-compressible fluid at a constant velocity. The method is used to predict the wetted length, the height of water pile-up, the pressure distribution and the overall force on the wedge. The accuracy of the numerical results is demonstrated through comparisons with data reported in the literature.

Fluid Dynamic Investigation of Channel Design in High Temperature PEM Fuel Cells

In this paper we analyze the three-dimensional flow field in anode and cathode gas channels of polymer electrolyte membrane (PEM) fuel cells operating at high temperature (T > 100°C). Different gas flow channel designs (pin-type, parallel channels, comb-tipe and multiple serpentine), as well as different channel sections (squared, trapezoidal and rounded with different curvature radii) are evaluated in function of some relevant parameters. The analysis is performed accounting for overall pressure losses, gas distribution over the electrode area and residence time with focus on channel hydraulic diameter, active surface ratio, gas path. Differences with low temperature (LT) PEM fuel cell design are also adressed. The investigation is conducted by means of 3D-CFD softwares and the results of our simulations are compared to experimental data in literature.

Microbial Fuel Cells in Solid Waste Valorization: Trends and Applications

In recent years, biomass valorization (and, in general, waste treatment) and FC technology met in the so-called bioelectrochemical systems (BESs). BESs take advantage of biological capacities (microbes, enzymes, plants) for the catalysis of electrochemical reactions. They mainly include micro-electrolysis Cell (MECs) and microbial fuel cells (MFCs). While MECs can produce valuable compounds (like H2, CH4, etc.), providing a suitable potential at the electrodes, MFCs do not need any energetic input to convert chemical energy (stored in organic compounds) into electric power. In this “biologically-based-fuel–cells,” the fuel is made by different sources of organic compounds. Landfill leachate, municipal and agro-industrial wastewaters, sediments, solid organic wastes can be source of electric power and commodity chemicals. The use of MFC technology to waste treatment and valorization is, maybe, the most promising application of this newborn technology. Even though many researchers proved the reliable utilization of liquid waste as fuel in scaled MFCs, few attempts to apply MFCs to solid waste valorization have been done. In this paper, recent studies about the application of MFCs to solid substrates treatment and valorization and the contribution that BESs and MFC in particular could give to the development of a more sustainable waste management.

Fluid-structure interaction during the water entry of flexible cylinders

In this work, we experimentally study the water entry of flexible cylinders. Experiments are performed in free fall and we explore variations of the entry velocity by varying the drop height. High speed imaging is utilized to study the fluid kinematics, the pile-up evolution, the cavity formation, and the overall structural deflection. The impact dynamics is analyzed through accelerometers, whereby fibre bragg gratings (FBG) measure the punctual deformation at characteristic locations on the cylinder surface. A modal decomposition approach is utilized to reconstruct the overall structural deflection from the punctual strain measurements. The proposed reconstruction methodology is compared against high-speed images. Results show that during the water entry the cylinder mainly deforms in the direction of the hydrodynamic loading, whereby marked vibrations whose amplitude increase with the entry velocity dominate the dynamic response.

Dynamic monitoring of compliant bodies impacting the water surface through local strain measurements

The understanding and the experimental characterization of the evolution of impulsive loading is crucial in several fields in structural, mechanical and ocean engineering, naval architecture and aerospace. In this regards, we developed an experimental methodology to reconstruct the deformed shape of compliant bodies subjected to impulsive loadings, as those encountered in water entry events, starting from a finite number of local strain measurements performed through Fiber Bragg Gratings. The paper discusses the potential applications of the proposed methodology for: i) real-time damage detection and structural health monitoring, ii) fatigue assessment and iii) impulsive load estimation.

Front-tracking lattice Boltzmann simulation of a wedge water entry

In this work, we present the implementation of a front-tracking variant of the lattice Boltzmann method to model water entry problems. In this method, the fluid is considered incompressible, the gas dynamics is neglected and the free surface is represented through a layer of interface cells, whose dynamics is described using the mass and momentum fluxes across it. The consistency and accuracy of the computations is demonstrated through comparisons with theoretical solutions and experimental data reported in the literature.

Use of a Metal Organic Framework for the Adsorptive Removal of Gaseous HCl: A New Approach for a Challenging Task

In this work, the potentialities of the amino-functionalized, chromium-based MIL-101 metal organic framework (NH2-MIL-101) as a high capacity, fully regenerable hydrogen chloride adsorbent have been proved by a thorough adsorption thermodynamics investigation. The chosen adsorbent showed high gaseous HCl adsorption capacities and, to the best of our knowledge, it is the first example of a totally regenerable substrate for this kind of adsorbate, as evidenced by both experimental and modeling results. This paves the way to the implementation of greener, more energetically efficient pressure/temperature swing adsorption processes to purify biogas feeds for high-temperature fuel cells.

Life Cycle Cost Analysis of Hydrogen Energy Technologies

Abstract Today, in the global economy, characterized by a growing awareness of environmental issue, the life cycle costing analysis (LCCA) is receiving increasing attention in various sectors. This is a critical task for modern businesses. In fact, the procurement decisions for many products are made on their life cycle costs. In this context, the hydrogen technologies play an important role. Actually, even though they have been known for a long time, aspects of system analysis, energy economics, and ecology received much less attention. For those reasons, the aim of this work is twofold. First, this study aims to contribute to the development of a comprehensive study on LCCA of hydrogen energy technologies. Second, it aims to propose a simple framework, called “ABC” analysis based on life cycle cost approach and multicriteria decision analysis useful to carry out an integrated analysis to compare different results and to balance economic data.

Structural health monitoring through fiber Bragg grating strain sensing

In this work, we leverage a modal decomposition analysis to develop a methodology for the live structural health monitoring. The proposed methodology relies on punctual strain measurements performed utilizing a fiber bragg grating (FBG) system. We propose an experimental measurement chain for the live monitoring of the structural kinetics and the distributed stress field. Its effectiveness is verified by performing experiments on the water entry of compliant bodies. Structural punctual strains are synchronously acquired at several locations by FBG sensors through a homemade high-speed optical interrogator. The structural deformation is reconstructed through its decomposition over a finite number of mode shapes. The combination of the high-speed FBG interrogator with the computationally inexpensive reconstruction technique based on modal decomposition allows for real time monitoring of structures subjected to impulsive loadings.