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Abstract Simulations were carried out to predict the performance of a Solar Rankine Cycle (SRC) and an Integrated Solar Combined Cycle (ISCC) when combined with two different solar field configurations based on parabolic trough and power tower systems. For the selected cases, yearly plant performance was computed under real operating conditions on a one hour basis. A computing procedure was developed by integrating two commercial softwares with in-house computer code. Thermodynamic performance was featured for every plant configuration both at nominal and part load conditions. A single reheat regenerative Rankine cycle was chosen for the SRC plant whereas a commercial gas turbine, i.e. Siemens SGT-800, with a dual pressure heat recovery steam generator (HRSG) was assumed for the ISCC plant. As far as the heat transfer fluid (HTF) is concerned, molten salt was chosen to transfer heat to the water loop in the SRC. Synthetic oil was considered in the ISCC plant. Plants were assumed to be located in a Southern Spain site. The comparative analysis was mainly focused on the influence of CSP technology on global solar energy conversion efficiency of both SRC and ISCC plants. Special attention was devoted to assess trough collectors (PTCs) against the solar tower (ST) system in terms of intercepted radiation and thermal power sent to the power block. The ISCC coupled with a ST was found to assure the highest annual solar-to-electric efficiency of 21.8%. This is the result of both higher collection efficiency of ST compared to PTCs and higher conversion efficiency of solar energy introduced into the combined cycle, as compared to SRC.

The paper discusses on a control algorithm applied to a hybrid PV power system. The hybrid power system is constituted by directly connecting an Electric Double Layer Capacitor (EDLC) device on the dc output bus of the PV Maximum Power Point Tracker (MPPT) converter. The aim of this paper is to propose a control approach applied to the dc power converter able to assure a double set-point regulation, which takes into account the operational constraints of both the PV power source and storage buffer. Control design is based on a cascade strategy. The controller parameters are synthesize basing on the State Space Averaging (SSA) method and low perturbation approach. A numerical simulator is set up in ®Matlab. The results of simulations aim to validate the features of the proposed approach.

AbstractStarting from the results of a research project on Solidarity Purchase Groups (Gruppi di Acquisto Solidale - GAS) in Italy, the paper discusses how, within consumer groups, for the very reason of their horizontal organisation which encourages learning amongst peers, the conditions are created to overcome the so-called ‘attitude-behaviour gap’ in ethical consumption. The analysis shows how after joining a solidarity consumer group and experimenting this kind of shared economic practice, people not only change their consumption but they also feel more collaborative and trustful towards others, more interested in politics and have an increased sense of social effectiveness.

There is limited scientific and grey literature studying the phenomenon of how the current job profiles are being affected by Industry 4.0 technologies at the operational level. This paper aims to answer the following question: how can the evolution of Workforce 4.0 job profiles be analyzed from a job-task perspective concerning the adoption of smart and digital technologies in manufacturing companies? To this end, it presents a task classification framework addressing three task classification dimensions, namely: (i) routine/nonroutine tasks, (ii) physical/cognitive tasks, and (iii) individual/social tasks, and a job-task analysis method to analyze the evolution of job profiles due to smart or digital technology adoption at the task level. Both artifacts were created using a state-of-the-art review to ground their conceptualization in the most recent knowledge available on work design and job-task analysis methods and were later evaluated and refined using an action-research approach to increase their applicability and usefulness for academic researchers and practitioners. The applicability of the proposed framework and method was demonstrated in an industrial case study discussing the theoretical and managerial contributions of these two artifacts for the development of Workforce 4.0 job profiles. It was concluded that the proposed framework and method are valuable artifacts that contribute to the limited universe of tools available in the literature to first analyze how operators’ tasks and roles change concerning the adoption of new Industry 4.0 technologies and then identify the requirements of new skills and competencies for the evolving and emerging job profiles on the shop floor.

The present paper investigates the effects of the application of trenched holes in the front part of a contoured film cooled endwall. Two trench configurations were tested, changing the trench depth. Tests have been carried out at low speed (M2is=0.2) and low inlet turbulence intensity level, with coolant mass flow rate ratio varied within the 0.5–2.5% range. Pressure probe traverses were performed downstream of the vane trailing edge to show the secondary flow field modifications and to evaluate trench additional losses. Endwall distributions of film cooling effectiveness have been obtained by the thermochromic liquid crystal (TLC) technique. For each injection condition, energy loss coefficient and film cooling effectiveness distributions were analyzed and compared with the ones obtained from rows of cylindrical holes. Laterally and area averaged effectiveness as well as pitch and mass averaged kinetic energy loss coefficients were computed to enlighten any change induced by the introduction of trenched holes. A uniform and high thermal coverage was obtained in the region just downstream of the trench, but it quickly decayed because of enforced mixing of coolant with main flow. Compared with the cylindrical hole configuration, trenches are able to provide a higher global cooling effectiveness, but a larger amount of coolant injection is required. The introduction of both trenches is responsible for a secondary thermodynamic loss increase of about 0.7% at low coolant injection rates. Increasing the blowing rates, the additional loss vanishes.

Research in the field of bioelectrochemical systems is addressing the need to improve components and reduce their costs in the perspective of their large-scale application. In this view, innovative solid separators of electrodes, made of biochar and terracotta, are investigated. Biochar-based composites are produced from giant cane (Arundo Donax L.). Two different types of composite are used in this experiment: composite A, produced by pyrolysis of crushed chipping of A.donax L. mixed clay; and composite B, produced by pyrolysis of already-pyrolyzed giant cane (biochar) mixed with clay. Electrical resistivity, electrical capacity, porosity, water retention, and water leaching of the two composites types (A and B) with 1, 5, 10, 15, 20, and 30 mass percentages of carbon (w/w) are characterized and compared. Less than 1 kΩ cm of electrical resistance is obtained for composite A with a carbon content greater than 10%, while physical and electrical performances of composite B do not significantly change. SEM micrographs and 3D microcomputed tomography of different composite materials are provided, demonstrating a different matrix structure of carbon in the terracotta matrix. The possibility of suitably decreasing electric resistance and increasing water retention/leaching of composite A opens the way for a new class of resistive materials that can be simultaneously used as electrolytic separators and as external electric circuits, allowing a compact microbial fuel cell design. A proof of concept of such an MFC design was provided for different tested composites. Although all the anolytes become anaerobic, only the MFCs equipped with the composite A30% were able to produce power, reaching the maximum power peak in correspondence to resistance of about 1 kΩ. The low, but significant, produced power (about 40 mW m−2, cathode area) confirm that the proposed solution is particularly suitable for nutrient recovery and environment pollution bioremediation, where energy harvesting is not requested.

Abstract We develop a sequential optimization model to analyze a circular economy framework where waste is collected by municipalities and it is partially reused by a recycling company for the production of electricity, thermal energy and other goods. The considered municipalities collect recyclable and not-recyclable waste types, sorted by citizens, which are sold to the recycling company and sent to landfill, respectively. Each municipality aims at maximizing its profits deriving from selling the recyclable waste to the recycling company, taking into account the waste collection and the dismantling costs. On the other side, the recycling company maximizes its total profit obtained from the difference between the revenues of selling the new goods produced and the costs of purchasing and treating recyclable waste. In this closed-loop supply chain, the municipalities define the prices at which they can offer recyclable waste to the recycling company and the tax that citizens has to pay for the waste management service. In contrast, the recycling company selects the processing volumes of recyclable waste to purchase depending on the offer prices set by the municipalities. In order to find the equilibrium of the whole supply chain, we propose an iterative decomposition method, applied to waste collection in the Lombardy Region in Italy, that accounts for the sequence of the decisions taken by the municipalities and the recycling company.