Stefano Cordiner

The use of a high temperature wind tunnel for MT-SOFC testing—Part I: detailed experimental temperature measurement of an MT-SOFC using an avant-garde high temperature wind tunnel and various measurement techniques

The purpose of the first part of this study was to compare four different temperature measuring methods. The application of these tools for possible temperature monitoring or calibration of monitors of microtubular solid oxide fuel cells (MT-SOFCs) is explored. It was found that a thermographic camera is very useful to visualize the temperature gradient on the outside of a cell, while an electrochemical impedance spectroscopy method was useful for estimating the core temperature of a test cell. A standard thermocouple was also used in combination with the previous two methods. Furthermore, an inexpensive laser guided thermometer was also tested for MT-SOFC temperature measurement. This initial study has opened up a range of questions not only about the effect of the experimental apparatus on the measurement results but also about the radial temperature distribution through a MT-SOFC in a working mode. Both these topics will be further investigated in part II of this study through a computational fluid dynamics study. This should provide additional interesting information about any differences between testing single cells and those within a bundle of cells. The discussed results are expected to be mainly temperature related, which should have direct consequences on power output and optimized gas inlet temperatures.

Torque Setpoint Tracking for Parallel Hybrid Electric Vehicles Using Dynamic Input Allocation

This paper addresses the coordinated control of the internal combustion engine and the electric motor in a parallel hybrid electric vehicle, when both of them are running. In deciding how much torque each motor contributes, both long term energy oriented and short term drivability goals must be considered. The first contribution in this paper consists of proposing an architecture in which three main functional blocks are present, namely a steady-state performance generator, providing an energy oriented torque contribution, a transient performance generator providing a drivability oriented torque contribution, and a dynamic input allocator blending the outputs of the other two blocks in such a way as to satisfy both the short and the long term goals. The second contribution consists in showing how the input allocator must be designed. The other two blocks can be designed following any of several recipes already described in the literature. Experimental validation of the proposed approach confirms the relevance of accounting for the different motor dynamics in the allocator design.

Numerical-Experimental Comparison of the Performance of a Partially Stratified Charge Natural Gas Fuelled Engine

Compressed natural gas (CNG) has great potential as an alternative fuel for vehicle engines, and can reduce emissions and improve fuel economy. A single cylinder research engine has been modified to enable direct injection of a small quantity of fuel near the spark plug, independently of an overall lean homogeneous charge. Thus a partially stratified charge is formed within the chamber, which allows significant extension of the lean limit of combustion. This results in an improvement in specific fuel consumption. Numerical simulation also plays an important role in the development of such technological solutions. 3D simulations, in particular, are desirable to provide complete information about thermal and fluid dynamical fields within the chamber. In particular, among the developed numerical tools linked to the KIVA-3V code, special attention was dedicated to the formulation of the combustion model (CFM) turbulent combustion model based on the flamelet hypothesis), to adequately model non-homogeneities and lean mixture compositions. In this paper an optimization procedure is assessed, with the ultimate goal of designing combustion chambers properly devoted to be operated under lean (homogeneous and PSC) mixture conditions. The results related to the procedure definition and to its experimental validation are presented. Experimental and numerical data have been compared in terms of pressure cycles and heat release rate profiles. The overall results are encouraging, taking into special account the difficulty to reliably predict the key performance parameters without any “tuning interventions”, even when mixture richness and homogeneity were varied.Copyright

Waste incineration in rotary kilns: a new simulation combustion tool to support design and technical change

This article presents a tool based on a simplified model developed for the combustion processes in a rotary kiln incinerator (slightly inclined rotating primary combustion chamber). The model was developed with the aim of supporting the design phase of the incinerator combustion chamber and, at the same time, of investigating possible technical changes in existing plants in order to optimise the combustion process and the dimension of the rotary kiln (length, diameter) as a function of the characteristics of the fed waste. The tool has been applied and the obtained results compared with a real incineration plant operating on healthcare waste located in Rome (Italy). The mass and thermal balances were taken into account, together with kinetic parameters for the combustion of the specific waste stream. The mass balance considered only the major mass components (carbon, hydrogen, oxygen, nitrogen and sulphur). The measured external temperatures appear to be in good agreement with the simulated results. A sensitivity analysis of the plant under different operating conditions was carried out using different input flow rates and excess air ratios, and an assessment was made of the refractory and insulator properties of the kiln’s behaviour. Some of the simulated results were used during the periodical maintenance to improve the refractory characteristics in order to reduce the fret and corrosion process.

Experimental and Numerical Study of Various MT-SOFC Flow Manifold Techniques: Single MT-SOFC Analysis

Standard anode supported micro tubular-solid oxide fuel cell (MT-SOFC) stacks may provide the oxidant, in relation to the fuel, in three different manifold regimes. Firstly, “co-flow” involves oxidant outside the MT-SOFC flowing co-linearly in relation to the fuel inside. Secondly, “counter flow” involves oxidant outside the MT-SOFC flowing counter-linearly in relation to the fuel inside the MT-SOFC. Finally, “cross-flow” involves the oxidant outside the MT-SOFC flowing perpendicular to the fuel flow inside the MT-SOFC. In order to examine the effect of manifold technique on MT-SOFC performance, a combination of numerical simulation and experimental measurements was performed. Furthermore, the cathode current tap location, in relation to the fuel flow, was also studied. It was found that the oxidant manifold and the location of the cathode current collection point on the MT-SOFC tested and modeled had negligible effect on the MT-SOFC’s electrical and thermal performance. In this study, a single MT-SOFC was studied in order to establish the measurement technique and numerical simulation implementation as a prerequisite before further test involving a 7 cell MT-SOFC stack. [DOI: 10.1115/1.4023216]

Heat and Mass Transfer Evaluation in the Channels of an Automotive Catalytic Converter by Detailed Fluid-Dynamic and Chemical Simulation

The role of numerical simulation to drive the catalytic converter development becomes more important as more efficient spark ignition engines after-treatment devices are required. The use of simplified approaches using rather simple correlations for heat and mass transfer in a channel has been widely used to obtain computational simplicity and sufficient accuracy. However, these approaches always require specific experimental tuning so reducing their predictive capabilities. The feasibility of a computational fluid dynamics three-dimensional (3D) model coupled to a surface chemistry solver is evaluated in this paper as a tool to increase model predictivity then allowing the detailed study of the performance of a catalytic converter under widely varying operating conditions. The model is based on FLUENT to solve the steady-state 3D transport of mass, momentum and energy for a gas mixture channel flow, and it is coupled to a powerful surface chemistry tool (CANTERA). Checked with respect to literature available experimental data, this approach has proved its predictive capabilities not requiring an ad hoc tuning of the parameter set. Heat and mass transfer characteristics of channels with different section shapes (sinusoidal, hexagonal, and squared) have then been analyzed. Results mainly indicate that a significant influence of operating temperature can be observed on Nusselt and Sherwood profiles and that traditional correlations, as well as the use of heat/mass transfer analogy, may give remarkable errors (up to 30% along one-third of the whole channel during light-off conditions) in the evaluation of the converter performance. The proposed approach represents an appropriate tool to generate local heat and mass transfer correlations for less accurate, but more comprehensive, 1D models, either directly during the calculation or off-line, to build a proper data base.

Spent coffee enhanced biomethane potential via an integrated hydrothermal carbonization-anaerobic digestion process

This study reports the implications of using spent coffee hydrochar as substrate for anaerobic digestion (AD) processes. Three different spent coffee hydrochars produced at 180, 220 and 250 °C, 1 h residence time, were investigated for their biomethane potential in AD process inoculated with cow manure. Spent coffee hydrochars were characterized in terms of ultimate, proximate and higher heating value (HHV), and their theoretical bio-methane yield evaluated using Boyle-Buswell equation and compared to the experimental values. The results were then analyzed using the modified Gompertz equation to determine the main AD evolution parameters. Different hydrochar properties were related to AD process performances. AD of spent coffee hydrochars produced at 180 °C showed the highest biomethane production rate (46 mL CH4/gVS.d), a biomethane potential of 491 mL/gVS (AD lasting 25 days), and a biomethane gas daily composition of about 70%.

Biomass furnace study via 3D numerical modeling

Purpose – In the recent years the interest toward the use of biomass as a fuel for energy conversion, along with the continuous tightening of regulations, has driven the improvement of accurate design techniques which are required to optimize the combustion process and simultaneously control pollutant emissions. In this paper the use of a 3D Computational Fluid Dynamics approach is analyzed to that aim by means of an application to an existing 50 MW biomass fixed-bed combustion furnace fueled by grape marc. The paper aims to discuss these issues. Design/methodology/approach – The studied furnace is an interesting example of biomass utilization as it may integrate biomass with organic residual by an industrial process. The numerical model has been implemented into an OpenFOAM solver, with an Eulerian-Lagrangian approach. In particular, the fully 3D approach here presented, directly solves for the gas and solid evolution in both the combustion bed and the freeboard. Special care has also been devoted to the...

Dynamic input allocation of torque references for a parallel HEV

A novel strategy for the dynamic managment of the load request for the Internal Combustion Engine (ICE) and the Electrical Motor (EM) in a parallel hybrid vehicle is presented. The goal is the performing of a load splitting between ICE and EM subject to the achievement of good drivability of the vehicle in terms of coherence of the torque supply with the driver request (transient performance) for every load splitting between the two motors (static performance). In particular a dynamic allocation scheme is proposed, which dynamically distribute the power demand among the two propulsion systems, using suitable characterizations of their dynamics. Its stability and convergence properties are formally proven and the effectiveness of the control scheme is illustrated via simulations.

Polymer Electrolyte Fuel Cell Design Based on Three-Dimensional Computational Fluid Dynamics Modeling

An entirely numerical design procedure, based on computational fluid dynamics, is introduced to evaluate the performance of different polymer electrolyte fuel cell layouts and sets of operating conditions for assigned target parameters in terms of performance. The design procedure has been applied to a coflow design, characterized by large active area (500 cm 2 ), moderate temperature (70°C), liquid cooling, and metal supporting. The role of heat transfer between the cell and the cooling system is analyzed to properly address the influence of operating conditions on power density and flooding via a comprehensive parametric analysis.