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A new concept of a system for Combined Heat and Power generation is presented. The concept is based on hybrid use of two renewable energy sources, direct solar (thermodynamic solar) and biomass (indirect solar energy). Biomass combustion is conducted using a fluidized bed combustor. A second source of energy, given by the direct irradiation of the bed with a concentrated solar radiation, is integrated in the same system, using the fluidized bed as solar receiver. A Stirling engine converts heat into mechanical power. A Scheffler type mirror is adopted to allow irradiation of the system in a fixed focal point. Advantages of the proposed solution are illustrated and some preliminary results on the performance of the system, obtained with a simple model, are presented. The principal improvements with respect to existing systems of similar size and primary energy source are illustrated. The most important are the enhanced heat transfer processes that are realized with the help of the fluidized bed, and the possibility of continuous cogeneration during the day. Different working conditions are considered to estimate the contribution given by the burning of fuel, in presence as well as in absence of sun irradiation (as during the night). The distribution of energy shares among the different flux contributes is reported versus the amount of biomass burned per unit time. The results clearly demonstrate the advantage of coupling, in the same system, two sources for heat generation, thus maintaining the option of producing electricity without the supply of biomass fuel.

An accurate evaluation of solar energy production in power grids is a crucial aspect for the optimal exploitation of the available resources and for the effective integration of photovoltaic (PV) generators. This is especially advantageous in a smart grid context where a higher penetration of renewable energy sources is expected combined with distributed intelligence and information and communication technology (ICT) infrastructures. In this paper the nonlinear autoregressive network with exogenous input (NARX) is used to perform hourly solar radiation forecasting, according to a multi-step ahead approach. Temperature has been considered as the exogenous variable in the analysis. The NARX topology selection is supported by a combined use of two techniques: 1. a genetic algorithm (GA)-based optimization technique for the determination of the best weight set and 2. a method that determines the optimal network architecture by pruning it according to the Optimal Brain Surgeon (OBS) strategy. The considered variables are observed at hourly scale in a seven year dataset and the forecasting is done for several time horizons in the range from 8 to 24 hours-ahead. 29th European Photovoltaic Solar Energy Conference and Exhibition; 2574-2579

Biomass can play a key role in the development of distributed micro-generation appliances, allowing an easy and safe storage of energy in view of satisfying energy needs for the next future. As result of a recent project, called Megaris [1], a new micro CHP system has been proposed. Essentially, the system consists of a fluidized bed combustor with the heat transfer head of a Stirling engine in direct contact with the bed, where very low emissions can be achieved with a large variety of biomass sources, together with very high heat transfer coefficients towards the engine, raising its efficiency to competitive levels. To develop and optimize a configuration ready for introduction into the market, a reliable and fast model is required. In this work, a hybrid dynamic model is presented, consisting of a set of ordinary differential equations and of a Neural Network submodel introduced for those aspects that cannot be represented by lumped parameter models. The resulting model must correctly reproduce effects due to the fluidization regime that effectively establishes as working conditions are changed, both on heat transfer coefficients and on combustion efficiency. Results of the model are compared with experimental data collected on a prototype of the combustor equipped with a Stirling engine. The model is able to correctly reproduce the dynamic behavior of the system under different working conditions, with the accuracy required to perform design and optimization analysis. Proceedings of the 23rd European Biomass Conference and Exhibition, 1-4 June 2015, Vienna, Austria, pp. 724-731

In this work, thermocouple particle densitometry (TPD) has been demonstrated to be a valid tool for the analysis of combustion-formed carbon nanoparticles. The TPD methods has been successfully used to describe both particle volume fraction and the chemical evolution of carbonaceous nanoparticle in an ethylene/air premixed flame. Scanning mobility particle sizer (SMPS) and Raman spectroscopy have been used in comparison with the TPD analysis and to corroborate the TPD results. As a result, TPD has shown excellent agreement to the SMPS particle volume fraction measurements along the entire flame, starting from the very low values at the inception region. Furthermore, TPD has shown a clear evidence that the two classes of carbon nanoparticles, i.e. the two modes of the particle size distribution, strongly differentiate in terms of their graphitization degree based on the different values of emissivity of the material deposited on the thermocouple. While primary soot particle, i.e. those with diameter 10-20 nm, present emissivity of approximatively 1, thus acting as a black body, nucleated nanoparticles present emissivity values of about 0.5-0.6 indicating that they have a lower graphitization degree, i.e. higher content of organic carbon as compared the grown ones. Finally, Raman scattering, measured directly on the thermocouple previously coved by carbon nanoparticle, supported the TPD analysis. The possible use of TPD as valid, reliable and cost-effective combustion aerosol sensor in hot gas-stream is discussed.

When the degradation growth of a unit depends only on its age, a widely accepted model to describe the degradation phenomenon is the non-homogeneous gamma process, which proved to be suitable to model such degradation phenomena as wear, fatigue, corrosion, crack growth, erosion, and consumption. In this paper, a Bayesian inferential procedure using the Markov Chain Monte Carlo technique is proposed for the non-homogeneous gamma process with power-law shape function. All the process parameters are left to be assessed, and prior information is formalized on some quantities having a "physical" meaning. Both vague and informative priors are provided. Point and interval estimation of the process parameters and of some functions thereof are developed, as well prediction on some observable quantities that are useful in defining the maintenance strategy is proposed. Finally, the proposed procedure is applied to a real dataset consisting of the sliding wear data of four metal alloy specimens.

Coating systems protect metal substrates from environmental corrosion attack. However, although having good performances, the presence of specific metal ions in their composition represents a potential source of environmental contamination. The necessity to conciliate corrosion protection with environmental impact is; thereby, primary. This work was designed to study the performance of low environmental impact conversion coatings (surface pre-treatment and high-solids epoxy primer), such as those free from hexavalent chromium (Cr VI), layered on different substrates of aluminium alloy [Al 7075 (T6) unclad and Al 2024 (T3) unclad] widely used in aerospace applications. Substrate surfaces were first treated by environmentally friendly Cr-free products. Successively, on pre-treated substrates, high-solids, chromate-free epoxy primer was applied. The capability to protect substrates from corrosion phenomena was evaluated following exposure of 4 groups of samples to in situ marine atmosphere at the Genoa Experimental Marine Station (G.E.M.S.) of CIV.R.-I,SMAR., located in the port of Genoa, for 8, 16, and 24 months and in accordance with UNI EN ISO 8565:1997 Standard. Accelerated degradation of conversion coating was also studied by electrochemical impedance spectroscopy. To characterize the coating systems, the interface metal substrate/conversion coating, sections from different samples were submitted to microscope techniques. The experimental results reported in this paper give useful information regarding the protective power against substrate corrosion of some Cr-free conversion coatings that have, as compared to traditional Cr VI containing products, a lower impact on workers' health and on the environment.

Methane steam reforming(MSR) was studied in a membrane reactor(MR) with a Pd-based and a porous alumina membranes. MRs showed methane conversion higher than that foresaw by the thermodynamic equilibrium for a traditional reactor(TR). Silica membranes prepared at KRICT were characterized with permeation tests on single gases(N?, H?and CH?). These silica membranes can be also used for high temperature applications such as H?separation CO?hydrogenation for methanol production is another reaction where H?O selective removal can be performed with these silica membranes.

Various academic studies show that in the use of common ICE Off-road Vehicles only about 10-15% of the available power at fuel level is actually transformed into useful energy for the actuators.Particularly the Directional Control Valves are responsible for the dissipation of about 35-40% of the hydraulic energy available at the pump level.The machine electrification trend makes it even more urgent to optimize the hydraulic system to ensure greater performance and higher battery autonomy.Traditional Directional Control Valves design solutions neglect important opportunities for reducing losses and improve internal regeneration. Especially, energy recovery is rarely applied and in any case by means of important superstructures which considerably increase the costs of the system.This paper presents an innovative Directional Control Valve layout, based on the Downstream Compensation approach that,in a simple and cost-effectivedesign, allows to recover a considerable amount of energy from both the inertial loads and the simultaneous use of multiple actuators at different pressure level.The proposed layoutperformance and efficiency arestudied through lumped element simulation and laboratory experimental tests.