Design optimization of a SOFC-based CHP system through dynamic analysis

In this paper a complete dynamic model of a solid oxide fuel cell (SOFC)-based residential cogenerative (CHP) energy system has been developed, with particular attention to the heat exchangers, also in consideration to the transient response (in terms of the electricity and heat production) of the whole system.     

Diagnosis methodology for the turbocharger groups installed on a 1 MW internal combustion engine

The issue of internal combustion engine (ICE) diagnosis attracts great interest because modern engines need continual control of the operational status, in order to obtain high efficiency in energy conversion and accurate control of the polluting emissions. In particular, in reference to an alternative ICE of 1 MW, the present study relates the development, through the design of neural simulators, of the turbocharger maps to reproduce the operational states characterized by new&clean conditions and allowing the evaluation of particular “health state” indices of such a module. In detail, after an experimental campaign, turbocharger fundamental characteristics referred to new&clean conditions, such as the compressor isoentropic efficiency and the mass flow elaborated by the turbine, were evaluated at different operation conditions of the alternative ICE Subsequently, the neural simulators were developed through the training and test of different neural architectures.     

Oxidation of proteins: Basic principles and perspectives for blood proteomics

Protein oxidation mechanisms result in a wide array of modifications, from backbone cleavage or protein crosslinking to more subtle modifications such as side chain oxidations. Protein oxidation occurs as part of normal regulatory processes, as a defence mechanism against oxidative stress, or as a deleterious processes when antioxidant defences are overcome. Because blood is continually exposed to reactive oxygen and nitrogen species, blood proteomics should inherently adopt redox proteomic strategies. In this review, we recall the biochemical basis of protein oxidation, review the proteomic methodologies applied to analyse redox modifications, and highlight some physiological and in vitro responses to oxidative stress of various blood components.     

Cylinders diagnosis system of a 1 MW internal combustion engine through vibrational signal processing using DWT technique

In the present study an innovative diagnostic system of the combustion process, developed especially for cogenerative reciprocating engines, is introduced. This work is part of a more wide research activity, dedicated to the development of diagnostic systems for energy plants. This system is based on the evaluation of the energy content of the vibration signal directly acquired on the cylinders head through the Discrete Wavelet Transform technique and the Parseval’s theorem. The system development and its test took place alongside a consistent maintenance work that has allowed to distinguish between different engine operative functioning, and, in particular, between good and bad conditions of the combustion chambers. Then, starting from the obtained results, a diagnostic system has been developed, basing on the acquired vibration signals and the operative engine load, in order to formulate for each cylinder a judgment about the quality of the combustion process.     

On the feasibility of on-farm biogas-to-electricity conversion: To what extent is solid oxide fuel cells durability a threat to break even the initial investment?

Despite their promising features, adverse economic feasibility still hamper SOFCs wide implementation and this effect is emphasized as long as the system size is reduced. According to previous investigations, the biogas pre-treatment section represents a burden for the economic viability. Aiming at reducing the extent of installation costs in SOFC-based configurations, biogas partial upgrading through CO₂ gas-separation membranes is put forth as innovative solution against reforming. This innovative system concept is expected to make SOFCs more cost-effective, yet resulting feeding gas might cause a quicker SOFC performance decay. Besides solving this trade-off, the economic viability results strongly sensitive to subsidiary electricity prices in force according to the regulatory framework.This paper presents a comparative economic assessment regarding biogas-to-electricity conversion via Solid Oxide fuel cells (SOFCs) and mature technologies as internal combustion engines (ICEs). Results highlighted that, the innovative SOFC system is far more viable than reforming-based one, exhibiting a reasonable payback time, with an adequate subsidized electricity sale price (4 and 5 years for small/medium and large-size plants respectively when subsidy is 0.28 €/kWh), up to 1%_1000h degradation rate. On the other hand, whilst considering a SOFC degradation rate of 0.03%_1000h, the reforming-based system appears feasible only on large-size plants, yet recovering the initial capital expenditure in 9 years. Moreover, once the break-even point is reached, the gain in the net revenue produced by the innovative system is amplified in the event of small-size installation. This allows the possibility to undertake the risk of higher degradation rates (up to 2%_1000h) without jeopardizing the economic profitability. Therefore, in the present regulatory framework and under current capital costs projections, the innovative SOFC system appears as much profitable as ICE mature technology. Such effort in the design of the fuel pre-treatment unit can lever SOFC broad spreading into the market of small biogas producers.     

Air variation in SOE: Stack experimental study

Solid oxide electrolyzer are the electrolysis technology that can achieve higher efficiency and power densities. This study aims to analyze the role of air when used as a sweep gas in the oxygen electrode of a SOE. Based on experimental activity on a SOE stack, both polarization and constant utilization tests were performed changing the air flow rate in the stack. Due to air reduction, oxygen concentration of off gasses was increased from 25% up to 50%. All experimental results indicated that, reducing air flow down to 9% of nominal value, the effect on performances is negligible and variation of voltage is maintained below 2%. Thermoneutral condition was achieved at 500 mA cm^?2. Advantages of air reduction in SOE operation stand in both capital and operation costs. System design is simplified, ancillary consumptions are reduced and, in view of oxygen as a by-product, high oxygen concentrated off gases are produced with lower energy request for possible O₂ separation.     

Plasmon hybridization engineering in self-organized anisotropic metasurfaces

Nano Research - The engineering of self-organized plasmonic metasurfaces is demonstrated using a maskless technique with defocused ion-beam sputtering and kinetically controlled deposition. The...     

An updated numerical model of the Larderello–Travale geothermal system, Italy

Larderello–Travale is one of the few geothermal systems in the world that is characterized by a reservoir pressure much lower than hydrostatic. This is a consequence of its natural evolution from an initial liquid-dominated to the current steam-dominated system. Beneath a nearly impermeable cover, the geothermal reservoir consists of carbonate-anhydrite formations and, at greater depth, by metamorphic rocks. The shallow reservoir has temperatures in the range of 220–250 °C, and pressures of about 20 bar at a depth of 1000 m, while the deep metamorphic reservoir has temperatures of 300–350 °C, and pressures of about 70 bar at a depth of 3000 m. The 3D numerical code “TOUGH2” has been used to conduct a regional modeling study to investigate the production mechanism of superheated steam, the interactions between the geothermal field and the surrounding deep aquifers, and the field sustainability. All the available geoscientific data collected in about one century of exploration and exploitation have been used to provide the necessary input parameters for the model, which covers an area (4900 km²) about 10 times wider than the Larderello–Travale geothermal field (400 km²). The numerical model explains the origin of the steam extracted in about one century of exploitation and shows that, at the current level, the production is sustainable at least for the next 100 years.     

Prediction of geothermal well pressure and temperature profiles

The existing MIDA data bank is dedicated to experimental data of pressure drops and densities of two-phase mixtures flowing in rectilinear ducts; to this was added a MIDA-G sub-bank to collect experimental pressure and temperature profiles in two-phase mixtures in geothermal wells. To date 1879 items of data of 27 pressure and temperature profiles have been collected in five geothermal wells. The previously developed two-phase pressure drop correlation, CeSNEF-2, was used to predict these pressure and temperature profiles, given the bottom-hole data. Results are good for pressure profiles, but are less satisfactory, although acceptable, for temperature profiles. Possible explanations are: these “in-the-field” data are less accurate than laboratory data; an unpredictable modification of the inside surface; uncertainties in heat losses, both along the well and between the different wells; unreliability of the thermodynamic equilibrium hypothesis and of the Dalton and Henry laws in this environment.