Suolo, sistemi locali di produzione ed agricoltura nello sviluppo rurale delle economie post-industriali

The post-industrial development of non-urban territory shows a decline in the agricultural use of the land and a rise of industrial and services activities localization on it. This imply a new methodology to study rural and agricultural development. The aim of the paper is to provide a general framework to deal with these problems. The starting point is the use of soil as an input of production and as a space of the localization strategies of the firm

Aerodynamic and thermal characterization of turbocharger turbines: experimental and computational evaluation

Turbochargers are widely used in both passenger and commercial vehicle applications to increase power density, improved fuel economy leading to significant emissions reductions. In recent years, car manufacturers have introduced turbochargers widely in the diesel market in response to the stricter regulations in exhaust emissions. Although investment in turbocharger technology has made it possible to overcome issues related to reliability and cost, research is much needed in the area of design, testing methodologies and model development. This is particularly the case when considering unsteady flow effects. Computational codes are used by engine manufacturers to predict its performance and size components; prediction accuracy is crucial in this process. This thesis contributes to this process in several ways: steady modelling and heat transfer predictions. Furthermore, most aero-thermal design and analysis codes need data for validation; often the data available falls outside the range of conditions the engine experiences in reality leading to the need to interpolate and extrapolate excessively. The current work also contributes to this area by providing extensive experimental data in a large range of conditions. A further contribution of this work is the understanding of the turbine performance under pulsating flow; it shows that this performance deviates from the commonly used quasi-steady assumption in turbocharger/engine matching. A turbocharger is subjected to high temperature conditions; heat transfer within the turbine and the compressor severely affects the compressor performance at low rotational speeds and mass flow rates. Compressor maps provided by turbocharger manufacturers do not usually take into account the effects of heat transfer; this causes a mismatch when fitting the maps into engine codes which is detrimental to the overall engine performance prediction. The experimental investigation was conducted on three different turbine designs for an automotive turbocharger. The design progression was based on a commercial nozzleless unit modified into a variable geometry single as well as a twin-entry turbine configuration. The main geometrical parameters of these turbines were kept constant to allow equivalent performance assessment. The mixed-flow rotor used in this study consists of 12 blades with a constant inlet blade angle of +20°, a cone angle of 50° and a tip diameter of 95.2mm. The variable geometry stator consists of 15 vanes fitted into a ring mechanism, capable of pivoting in the range of 40° and 80° (with reference to the radial direction). The design progression into twin-entry turbine was completed by fitting a divider (accounting for only ≈6% of the overall internal volume) within volute. The turbine response for different vane angles (40° to 70°) and mass flow ratios between the two entries of the turbine was assessed. The turbine was tested under steady and pulsating flow conditions for two rotational speeds, 27.9 rev/s·√K and 43.0 rev/s·√K, a velocity ratio (U2/Cis) of 0.3 - 1.1 and a pulse frequency of 40 - 80Hz under both in-phase and out-of-phase conditions. A meanline aerodynamic model capable of predicting the performance parameters was developed for the nozzleless and the variable geometry single-entry turbine. The former was validated against experimental results spanning an equivalent speed range of 27.9 rev/s·√K and 53.8 rev/s·√K while the latter validated against one single speed (43.0 rev/s·√K) and three different vane angle settings (40°, 60° and 70°). The wide range of tests data from the Imperial College High Speed Dynamometer enabled the evaluation of the model in areas of the maps where currently no data exists. Based on the model prediction, a breakdown aerodynamic loss analysis was performed. As for the twin-entry turbine, the interaction between the two entries was investigated. Based on experimental evidence, a map-based method was developed to uniquely correlate the flow capacity within the entries for both partial and unequal admission. An investigation into the effects of heat transfer on a turbocharger was performed using a commercial turbocharger mounted on a 2.0 litre diesel engine. The global objective of these tests was to improve the understanding of heat transfer in turbochargers under realistic engine conditions. Measurements were obtained for engine speeds between 1000 and 3000 rpm at a step of 500 rpm – for each engine speed the load applied was varied from 16 to 250 Nm. In addition to the standard set of measurements needed to define the turbo operating point, the turbocharger was equipped with 17 thermocouples positioned in different locations in order to quantify the temperatures of the components constituting the turbocharger. A simplified 1-D heat transfer model was also developed and compared with experimental measurements. The algorithms calculate the heat transferred through the turbocharger, from the hot to the cold end by means of lump capacitances. The compressor performance deterioration from the adiabatic map was then predicted and based on the data generated by the model a multiple regression analysis was developed in order to assess the main parameters affecting the compressor non-adiabatic performance

Submarine depositional terraces at Salina Island (Southern Tyrrhenian Sea) and implications on the Late-Quaternary evolution of the insular shelf

The integrated analysis of high-resolution multibeam bathymetry and single-channel seismic profiles around Salina Island allowed us to characterize the stratigraphic architecture of the insular shelf. The shelf is formed by a gently-sloping erosive surface carved on the volcanic bedrock, mostly covered by sediments organized in a suite of terraced bodies, i.e. submarine depositional terraces. Based on their position on the shelf, depth range of their edge and inner geometry, different orders of terraces can be distinguished. The shallowest terrace (near-shore terrace) is a sedimentary prograding wedge, whose formation can be associated to the downward transport of sediments from the surf zone and shoreface during stormy conditions. According to the range depth of the terrace edge (i.e., 10–25 m, compatible with the estimated present-day, local storm-wave base level in the central and western Mediterranean), the formation of this wedge can be attributed to the present-day highstand. By assuming a similar genesis for the deeper terraces, mid-shelf terraces having the edge at depths of 40–50 m and 70–80 m can be attributed to the late and early stages of the Post-LGM transgression, respectively. Finally, the deepest terrace (shelf-edge terrace) has the edge at depths of 130–160 m, being thus referable to the lowstand occurred at ca. 20 ka. Based on the variability of edge depth in the different sectors, we also show how lowstand terraces can be used to provide insights on the recent vertical movements that affected Salina edifice in the last 20 ka, highlighting more generally their possible use for neo-tectonic studies elsewhere. Moreover, being these terraces associated to different paleo-sea levels, they can be used to constrain the relative age of the different erosive stages affecting shallow-water sectors

Recent Trends on Liquid Air Energy Storage: A Bibliometric Analysis

The increasing penetration of renewable energy has led electrical energy storage systems to have a key role in balancing and increasing the e ciency of the grid. Liquid air energy storage (LAES) is a promising technology, mainly proposed for large scale applications, which uses cryogen (liquid air) as energy vector. Compared to other similar large-scale technologies such as compressed air energy storage or pumped hydroelectric energy storage, the use of liquid air as a storage medium allows a high energy density to be reached and overcomes the problem related to geological constraints. Furthermore, when integrated with high-grade waste cold/waste heat resources such as the liquefied natural gas regasification process and hot combustion gases discharged to the atmosphere, LAES has the capacity to significantly increase the round-trip efficiency. Although the first document in the literature on the topic of LAES appeared in 1974, this technology has gained the attention of many researchers around the world only in recent years, leading to a rapid increase in a scientific production and the realization of two system prototype located in the United Kingdom (UK). This study aims to report the current status of the scientific progress through a bibliometric analysis, defining the hotspots and research trends of LAES technology. The results can be used by researchers and manufacturers involved in this entering technology to understand the state of art, the trend of scientific production, the current networks of worldwide institutions, and the authors connected through the LAES. Our conclusions report useful advice for the future research, highlighting the research trend and the current gaps.This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31—MCIU/AEI/FEDER, UE). This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación (AEI) (RED2018-102431-T). The authors at the University of Lleida would like to thank the Catalan Government for the quality accreditation given to their research group GREiA (2017 SGR 1537). GREiA is a certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work was partially supported by ICREA under the ICREA Academia program

improving liquefaction process of microgrid scale liquid air energy storage laes through waste heat recovery whr and absorption chiller

Abstract Liquid air energy storage systems (LAES) store liquid air produced by a liquefaction cycle and convert it into electric/cooling power when needed. A small-scale Liquid air energy storage system represents a sustainable solution in microgrid and distributed generation, where small energy storage capacities are required. The main drawback of these systems though, is the low round trip efficiency due to a high specific consumption of the liquefaction cycle. In this work, a single-effect absorption chiller using a Water-Lithium Bromide solution is integrated with a small air liquefier with a liquid air production capacity of 0.834 t/h. In the proposed solution, the waste heat of the compression phase of the liquefaction cycle is recovered and used to drive the absorption cycle, where the resulting cooling power is used to decrease the specific consumption and improving the exergy efficiency of the system. The operative parameters of the absorption chiller reflect the specifications of the most common commercial models available in the market and the size has been selected to maximize the heat power recovered. The results of simulation of the absorption chiller integration show a reduction of the specific consumption of around 10% (537 kWh/t to 478 kWh/t) and an increase of exergy efficiency of around 11.5%

parametric performance maps for design and selection of liquid air energy storage system for mini to micro grid scale applications

Abstract This paper aims to deliver new performance maps for "microgrid scale" Liquid Air Energy Storage system with a liquid air production of 1000 kg/h. By means of the performance maps, the impact of the main Liquid Air Energy Storage operative parameters, as well as the effect of the cold/warm thermal energy storage utilization factor, over the key performance indicators has been assessed and analyzed. The thermodynamics and sub-processes of the Liquid Air Energy Storage system are described in details and simulated by means of the software Aspen Hysys. Each performance map has been modelled by means of a sensitivity analysis carried out for the system operative parameters. Such a new methodology allows to select Liquid Air Energy Storage size and its related performance by means of a simple tool without the implementation of any complex numerical model

planning tool for polygeneration design in microgrids

Abstract This work suggests a methodology to assist the designer during the planning phase of microgrids and eco-districts. A mixed integer linear programming model is designed to mathematically describe the different energy systems and the physical relations among them. Given the different electrical/thermal demand profiles, the micro grid's topology and a set of boundary conditions, the model can identify the optimum mix of (poly-)generation units and energy storage systems, as well as the necessary district heating/cooling infrastructure. Both economic and energetic cost functions are defined to explore the problem from different perspectives. The described tool is applied to study an actual district of the NTU campus in Singapore, comprising 5 multi-purpose buildings and a district cooling network supplied by centralized electrical chillers. The planning tool was run to assess the optimal configuration that minimizes the overall cost (initial investment and OM the outcome results presented a layout and a mix of energy systems different from the present one. In particular, the optimal configuration results to be a district cooling system served by a mix of electrical chiller plant, trigeneration distributed energy system and sensible cold thermal energy storage

Traditional vs. novel approaches to coastal risk management: A review and insights from Italy

Coastal areas frequently face critical conditions due to the lack of adequate forms of land use planning, environmental management and inappropriate coastal risk management, sometimes leading to unexpected and undesired environmental effects. Risk management also involves cultural aspects, including perception. However, the acknowledgement of risk perception by stakeholders and local communities, as one of the social pillars of risk analysis, is often lacking.. Starting from an overview of the risk concept and the related approaches to be addressed, the paper investigates the evolution of coastal risk management with a focus on the Italian case study. Despite the design and adoption of national policies to deal with coastal risks, coastal management still shows in Italy a fragmented and poorly coordinated approach, together with a general lack of attention to stakeholder involvement. Recent efforts in the design of plans aiming at reducing risks derived from climate change and mitigating their impacts (National Strategy on Climate Change Adaptation; National Climate Change Adaptation Plan; National Recovery and Resilience Plan activities) should be effective in updating knowledge about climate change risks and in supporting national adaptation policies

Compressed Air Energy Storage—An Overview of Research Trends and Gaps through a Bibliometric Analysis

Electrical energy storage systems have a fundamental role in the energy transition process supporting the penetration of renewable energy sources into the energy mix. Compressed air energy storage (CAES) is a promising energy storage technology, mainly proposed for large-scale applications, that uses compressed air as an energy vector. Although the first document in literature on CAES appeared in 1976 and the first commercial plant was installed in 1978, this technology started to gain attention only in the decade 2000–2010, with remarkable scientific production output and the realization of other pre-commercial demonstrators and commercial plants. This study applies bibliometric techniques to draw a picture of the current status of the scientific progress and analyze the trend of the research on CAES and identify research gaps that can support researchers and manufacturers involved in this entering technology. Recent trends of research include aspects related to the off-design, the development of thermal energy storage for adiabatic CAES, and the integration of CAES with combined heating and cooling systems