bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Indirect Integration of Steam Rankine Cycles in Concentrated Solar Power Coupled with Thermochemical Storage
Authors: Tesio Umberto , Guelpa Elisa , Verda Vittorio
Published: October 2020

Storing energy in thermo-chemical form is a promising alternative for renewable energy sources and one of the fields that could exploit its advantages is constituted by Concentrated Solar Power (CSP). High efficiencies, high energy densities, long-term storage and dispatchability in power generation could be tackled with the employment of a Calcium-Looping in a central tower CSP plant. Although Brayton cycles based on sCO2 and He probably represent the most efficient option, it can be interesting to investigate the integration of Steam Rankine cycles because of the lower costs and the higher stage of development that characterize this technology. The present work has the purposes of studying this kind of integration and analyze the system in both energy and economic terms. To perform a comprehensive investigation, the power block layout and its thermal feeding strategy are included in the analysis and optimized. In addition, a multi-objective optimization is performed to evaluate possible compromises between the two most important aspects related to the entire power plant.
Leading agritourism facilities along Nearly Zero Energy paths: proposal of an easy-to-use evaluation method
Authors: Cirrincione Laura , Peri Giorgia , Rizzo Gianfranco , Scaccianoce Gianluca
Published: October 2020

The tourist sector, despite the present severe constraints imposed by the sanitary emergence, can be considered as an important component of almost all countries’ economies. In Italy agriturism, in particular, has been experiences a continuously rising trend in recent years. Clearly, such great interest towards these businesses also calls for a deep attention by an energy point of view, in sight of an energy efficiency improvement, hence a lowering of the pressure that such facilities exert to the natural environment. On the other hand, the European Union has been engaged, for a long time, in awarding the tourist accommodations environmental excellence brands, like the EU Ecolabel. Unfortunately, the achievement of such excellence brands requires the capability of managing complex energy and environmental data, which is often not the prerogative of people running such facilities. In order of contributing to overcome this difficulty, and with the aim of helping the addressing of agritourism towards a Nearly Zero Energy path, we propose here a simple approach that does not require the modelling and simulation of the energy behaviour of an agritourism, being essentially based on the application of easy-to-use ARERA (Italian Regulatory Authority for Energy Networks and Environment) datasheets scheme. On purpose, an application of the method, involving two typical Sicilian agritourism, is presented. The obtained results showed the viability of the proposed methodology, although the need of an update and/or replacement of some technical datasheets arose.
Numerical Assessment of Bioclimatic Architecture Strategies for Buildings Design in Tropical Climates: A Case of Study in Panama
Authors: Chen Austin Miguel , Castillo Milvia , de Mendes Da Silva Ángela , Mora Dafni
Published: October 2020

The increasing concern expressed by building designers in Panama, due to new building-energy regulations, regarding sustainable development goals and energy efficiency, is leading architects to reanalyse their design strategies and evaluate the vernacular architecture. The main implications of the hot-humid climate characteristics stipulate that the need for cooling of indoor environments drives buildings’ design and settlements. This work aims to assess the use of bioclimatic architecture strategies in three existing building typologies design in Panama, in terms of thermal comfort performance. The approach adopted here is to compare and analyse the vernacular architecture with current architecture. Besides, to evaluate bioclimatic architecture strategies based on recent investigations and the guidelines proposed by Givony, Olgyay, among others. A numerical assessment was performed on the dynamic simulation software DesignBuilder, where the building’s passive strategies are evaluated in terms of operative temperature, relative humidity (rH), PMV, PPD, and discomfort hours (DH). All three houses, the HVA, HCA, and HRES were tested in three different locations within Panama City. Results showed that the strategies in HVA perform best for reducing rH levels, but the HRES performs best in overall thermal comfort performance, apart yet from the high rH levels encountered.
Reconstruction and Analysis of the Energy Demand of a Healthcare Facility in Italy
Authors: Bianchini Alessandro , Carcasci Carlo , Manfrida Giampaolo , Zini Marco
Published: October 2020

The energy demand in healthcare and hospital premises has distinctive features. Due to specific constraints in terms of service continuity and indoor air quality, the demand is at a large extent constant during the day and throughout the year. Indeed, a healthcare facility must fulfil several different activities. Medical equipment needs electric energy, while the Heating, Ventilation and Air Conditioning systems require thermal energy. It is extremely difficult to define reference characteristics for the energy demand, since the proportions of the different consumptions are strongly connected with the specific activities/services carried out within each structure. The present work aims at analysing the energy demand of a healthcare facility located near Firenze (Italy). The energy demand has been analysed by means of the available documentation to get a basic knowledge of the expected consumption of each component of the facility. These data have been then correlated with information on the actual healthcare activity parameters (e.g. staff in service, medical services) and on weather conditions. As a result, the study led to the definition of the principal energy drivers that characterize the Healthcare Facility. The analysis procedure is thought of general interest for the community working in the field, representing a benchmark for the calibration of energy digital twins and a reference data set useful to carry out building energy efficiency optimization strategies.
sCO2 Power Plant for Industrial Waste Heat Recovery: a Case Study
Authors: Giovannelli Ambra , Biondi Matteo , Di Lorenzo Giuseppina , Salvini Coriolano
Published: October 2020

Industrial facilities release a large amount of heat as a byproduct of their processes. To improve environmental performance and increase the process profitability, this waste heat can be recovered and employed to generate power. Supercritical carbon dioxide (sCO2) systems have emerged as potential alternatives to the well-established technologies because of their high performance, reduced footprint and low water consumption. This paper aims to investigate the techno-economic feasibility of a sCO2 closed loop for power generation coupled with heavyindustrial processes, which make flue gases available at high-temperatures (above 400 °C).
Clustering of educational building load data for defining healthy and energy-efficient management solutions of integrated HVAC systems
Authors: Testi Daniele , Franco Alessandro , Conti Paolo , Bartoli Carlo
Published: October 2020

The COVID-19 pandemic is changing the way individuals, worldwide, feel about staying in public indoor spaces. A strict control of indoor air quality and of people’s presence in buildings will be the new normal, to ensure a healthy and safe environment. Higher ventilation rates with fresh air are expected to be a requirement, especially in educational buildings, due to their high crowding index and social importance. Yet, in this framework, an increased use of primary energy may be overlooked. This paper offers a methodology to efficiently manage complex HVAC systems in educational buildings, concurrently considering the fundamental goals of occupants’ health and energy sustainability. The proposed fourstep procedure includes: dynamic simulation of the building, to generate synthetic energy loads; clustering of the energy data, to identify and predict typical building use profiles; day-ahead planning of energy dispatch, to optimize energy efficiency; dynamic adjustment of air changes, to guarantee a safe indoor air quality. Clustering and forecasting energy needs are expected to become particularly effective in a highly regulated context. The technique has been tested on two university classroom buildings, considering pre-lockdown attendance. This notwithstanding, quality and significance of the obtained thermal energy clusters push towards a benchmark post-pandemic application.
Ammonia as hydrogen carrier for realizing distributed on-site refueling stations implementing PEMFC technology
Authors: Perna Alessandra , Minutillo Mariagiovanna , Di Micco Simona , Cigolotti Viviana , Pianese Adele
Published: October 2020

Ammonia is a particularly promising hydrogen carrier due to its relatively low cost, high energy density, its liquid storage and to its production from renewable sources. Thus, in recent years, great attention is devoted to this fuel for realizing next generation refueling stations according to a carbon-free energy economy. In this paper a distributed onsite refueling station (200 kg/day of hydrogen filling 700-bar HFCEVs (Hybrid Fuel Cell Electric Vehicles) with about 5 kg of hydrogen in 5 min), based on ammonia feeding, is studied from the energy and economic point of views. The station is designed with a modular configuration consisting of more sections: i) the hydrogen production section, ii) the electric energy supplier section, iii) the compression and storage section and the refrigeration/dispenser section. The core of the station is the hydrogen production section that is based on an ammonia cracking reactor and its auxiliaries; the electric energy demand necessary for the station operation (i.e. the hydrogen compression and refrigeration) is satisfied by a PEMFC (Proton-Exchange Membrane Fuel Cell) power module. Energy performance, according to the hydrogen daily demand, has been evaluated and the estimation of the levelized cost of hydrogen (LCOH) has been carried out in order to establish the cost of the hydrogen at the pump that can assure the feasibility of this novel refueling station.
Assessment of Feedstocks and Technologies for Advanced Biofuel Production
Authors: Cerruti Elena , Di Gruttola Francesca , Lauro Giancarlo , Valentini Teresa Dina , Fiaschi Paolo , Sorrenti Roberto , Borello Domenico
Published: October 2020

The present contribution deals with a comprehensive analysis of the available feedstocks and the appropriate technologies to produce advanced biofuels. The analysis is focused on the EU countries, since they adopted policy measures able to promote advanced biofuels as a strategic solution for a competitive and sustainable transport sector. In this regard, four classes of feedstocks have been taken into account: wastes, vegetable oils, agricultural and forestry residues. Their availability is studied with the aim to respect the European targets in terms of emissions without neglecting possible negative impacts on environment and biodiversity. A metric for the classification of the different solutions is proposed on the basis of feedstocks availability, technology readiness levels (TRL), quality of the produced biofuel as well as feedstock and production costs. It is possible to conclude that, even if the several interesting alternatives currently available have a high ranking in the proposed metric and must be taken in consideration, green diesel is today the most convenient solution for producing advanced biofuel without risks of technological failures and feedstocks shortage. This analysis can provide insights to encourage the development of advanced biofuels in EU, especially for some of the Member States as Germany, France and Italy.
Experimental Validation of a 3D-CFD Model of a PEM Fuel Cell
Authors: Riccardi Matteo , d’Adamo Alessandro , Vaini Andrea , Romagnoli Marcello , Borghi Massimo , Fontanesi Stefano
Published: October 2020

The growing energy demand is inevitably accompanied by a strong increase in greenhouse gas emissions, primarily carbon dioxide. The adoption of new energy vectors is therefore seen as the most promising countermeasure. In this context, hydrogen is an extremely interesting energy carrier, since it can be used as a fuel in both conventional energy systems (internal combustion engines, turbines) and in Fuel Cells (FC). In particular, PEM (Polymeric Electrolyte Membrane) FC are given growing attention in the transportation sector as a Life-Cycle viable solution to sustainable mobility.

The use of 3D CFD analysis of for the development of efficient FC architectures is extremely interesting since it can provide a fast development tool for design exploration and optimization. The designer can therefore take advantage of a robust and accurate modelling in order to define and develop fuel cell systems in a more time-efficient and cost-efficient way, to optimize their performance and to lower their production costs.

So far, studies available in the scientific literature lack of quantitative validation of the CFD simulations of complete PEM fuel cells against experimental evidence. The proposed study presents a quantitative validation of a multi-physics model of a Clearpak PEM cell. The chemistry and physics implemented in the methodology allow the authors to obtain both thermal and electrical results, characterizing the performance of each component of the PEM.

The results obtained, compared with the experimental polarization curve, show that the model is not only numerically stable and robust in terms of boundary conditions, but also capable to accurately characterize the performance of the PEM cell over almost its entire polarization range.
1D numerical study on hydrogen injection enabling ultra-lean combustion in a small gasoline Spark Ignition engine
Authors: Teodosio Luigi , Pirrello Dino , Marchitto Luca
Published: October 2020

This paper deals with the effects of hydrogen port injection on combustion evolution, efficiency and exhaust emissions of a small turbocharged gasoline Spark-Ignition engine through a 1D numerical code. First, the experiments on the base engine architecture are performed at different speeds and at low/medium loads. The experimental findings are used to validate a 1D model of the whole engine, developed within a commercial code. 1D model is also refined with “user-defined” sub-models for an accurate description of the in-cylinder phenomena, namely turbulence, combustion, heat transfer, and emissions. In a second step, 1D model is virtually modified through the installation of an hydrogen injector in each intake runner, while the combustion sub-model also accounts for the impact of hydrogen addition on the laminar flame speed through a dedicated correlation. 1D simulations are performed at low/medium loads and fixed speed of 2250 rpm with 5% of hydrogen by volume in the intake air. Numerical investigations show that hydrogen addition to gasoline/air mixtures allows relevant efficiency benefits (up to a maximum percent gain of 19%), while the NO emissions are almost eliminated. Consequently, hydrogen-boosted combustion represents a potential solution to achieve very high efficiency and reduced pollutant emissions of gasoline spark ignition engines equipped with a conventional combustion system.
3D-CFD Simulation of a GDI Injector Under Standard and Flashing Conditions
Authors: Sparacino Simone , Berni Fabio , Riccardi Matteo , Cavicchi Andrea , Postrioti Lucio
Published: October 2020

In the optimization of GDI engines, fuel injection plays a crucial role since it can affect the combustion process and, thus, fuel efficiency and pollutant emissions. The challenging task is to obtain the required fuel distribution and atomization inside the combustion chamber over a wide range of engine operating conditions. To achieve such goals, flash-boiling can be exploited. Flash-boiling is a phenomenon occurring when fuel temperature exceeds saturation temperature or, similarly, when ambient pressure is lower than saturation one. Under these conditions, which can occur inside the injector or directly in the combustion chamber, the fuel undergoes extremely accelerated breakup and quickly evaporates. The proposed manuscript shows the application of an alternative flashboiling model, recently implemented by Siemens-PLM in STAR-CD V.2019.1, to be applied in 3D-CFD Lagrangian simulations of GDI sprays. Results are validated against experimental data, provided by the SprayLAB of the University of Perugia, on a single-hole research injector. The new flash-boiling model consists of three main parts: an atomization model able to compute droplet initial conditions and the overall spray cone angle; an evaporation model and, finally, a droplet break-up model; the last two models are designed to simulate all the physical events occurring when droplets are injected into the combustion chamber. As for the investigated operating condition, vessel pressure and temperature are 40 kPa and 293K, respectively; as for the fuel (n-Heptane) temperature, it ranges from 303.15 K to 393.15 K, on equal injection pressure (10 MPa). The numerical-experimental comparison is carried out in terms of liquid penetration, imaging, and droplet sizing.
A Numerical Analysis of the Air-Cooling System of a Spark Ignition Aeronautical Engine
Authors: Faruoli Maria , Viggiano Annarita , Caso Paolo , Magi Vinicio
Published: October 2020

It is well known that spark ignition internal combustion engines for aeronautical applications operate within a specific temperature range to avoid structural damages, detonations and loss of efficiency of the combustion process. An accurate assessment of the cooling system performance is a crucial aspect in order to guarantee broad operating conditions of the engine. In this framework, the use of a Conjugate Heat Transfer method is a proper choice, since it allows to estimate both the heat fluxes between the engine walls and the cooling air and the temperature distribution along the outer wall surfaces of the engine, and to perform parametric analyses by varying the engine operating conditions. In this work, the air-cooling system of a 4-cylinder spark ignition engine, designed by CMD Engine Company for aeronautical applications, is analysed in order to evaluate the amount of the air mass flow rate to guarantee the heat transfer under full load operating conditions. A preliminary validation of the model is performed by comparing the results with available experimental data. A parametric study is also performed to assess the influence of the controlling parameters on the cooling system efficiency. This study is carried out by varying the inlet air mass flow rate from 1.0 kg/s to 1.5 kg/s and the temperature of the inner wall surfaces of the engine combustion chambers from 390 K to 430 K.
A one-dimensional model for the motor oil-fuel dilution under gasoline engine boundary conditions
Authors: Mariani Valerio , Bianchi Gian Marco , Cazzoli Giulio , Falfari Stefania
Published: October 2020

Nowadays the climate change caused by the green-house effect increasing is a world-wide issue with which scientists have to face. Being the passenger vehicles filled with fossil fuels, the emission of the carbon dioxide green-house gas is unavoidable. In order to slowdown both the global warming and the fossil fuels wasting, lower fuel consumptions, thus high efficiency engines, are required. Currently, the coupled use of downsizing and direct injection in spark ignited engines meets both high efficiency and power-demand requirements. Being downsized engines more compact, the distance between the injector and the engine walls are shorter. Thus, depending on the engine operating condition, the fuel spray wall impingement may occur leading to the formation of a liquid fuel film. If the wall impingement occurs against the cylinder liner wall, which is wetted by a thin oil layer, the motor oil and the landed fuel dilute until the piston arrival. At this time, the mass transport by diffusion have promoted the creation of an oil-fuel mixture. Thus, while thicker part of the mixture layer is scraped into the piston top land crevice, the thinner, whose properties are degraded by the fuel contamination, remains on the cylinder liner. The mixture accumulated inside the crevice may be scattered due to the piston inertia leading to the oil detachment and transport in the combustion chamber. The latter may cause both abnormal combustions named preignitions at high loads and increased particulate emissions at low loads, cold states, and cat-heating. This paper reports the implementation of a onedimensional numerical model for the dilution between fuel and motor oil in a stroke of a gasoline engine. The model aims to give the composition of the oil-fuel mixture both on the cylinder liner after the piston arrival and in the piston top land crevice.
A Preliminary 1D-3D Analysis of the Darmstadt Research Engine Under Motored Condition
Authors: Iacovano Clara , Berni Fabio , Barbato Alessio , Fontanesi Stefano
Published: October 2020

In the present paper, 1D and 3D CFD models of the Darmstadt research engine undergo a preliminary validation against the available experimental dataset at motored condition. The Darmstadt engine is a single-cylinder optical research unit and the chosen operating point is characterized by a revving speed equal to 800 rpm with intake temperature and pressure of 24 °C and 0.95 bar, respectively. Experimental data are available from the TU Darmstadt engine research group. Several aspects of the engine are analyzed, such as crevice modeling, blow-by, heat transfer and compression ratio, with the aim to minimize numerical uncertainties. On the one hand, a GT-Power model of the engine is used to investigate the impact of blow-by and crevices modeling during compression and expansion strokes. Moreover, it provides boundary conditions for the following 3D CFD simulations. On the other hand, the latter, carried out in a RANS framework with both highand low-Reynolds wall treatments, allow a deeper investigation of the boundary layer phenomena and, thus, of the gas-to-wall heat transfer. A detailed modeling of the crevice, along with an ad hoc tuning of both blow-by and heat fluxes lead to a remarkable improvement of the results. However, in order to adequately match the experimental mean in-cylinder pressure, a slight modification of the compression ratio from the nominal value is accounted for, based on the uncertainty which usually characterizes such geometrical parameter. The present preliminary study aims at providing reliable numerical setups for 1D and 3D models to be adopted in future detailed investigations on the Darmstadt research engine.
Application of the Sectional Method to Investigate Particle Number and Soot Mass in Ethanol and Gasoline Fueled Premixed Spark Ignition Engines
Authors: Pessina Valentina , Del Pecchia Marco , Breda Sebastiano , Dalseno Luca , Borghi Massimo
Published: October 2020

Emission modelling is still a timely topic in the engine research community. Soot emission reduction has gained its spotlight among the pollutants-related issues mainly due to the renewed interest in Gasoline Direct Injection. The conjunction of experimental measurements and numerical investigations provides an effective tool to cope with the constant evolution of the emission regulations. Thus, numerical models must be validated over a wide range of engine operating points and fuels. To this aim, the Sectional Method was applied to investigate Particulate Matter and Particle Number produced during combustion in a premixed spark ignition engine using 3D-CFD. Soot-related quantities were investigated for different values of equivalence ratio (from 1.0 up to 1.5) as well as for different fuels. Three different fuel types were examined: a commercial nonoxygenated American gasoline (TIER-2), a commercial Chinese gasoline (CHINA-6) with ethanol 10 %vol and pure Ethanol (E100). A detailed chemistry-based tabulated approach was exploited to compute a dedicated soot library, for each of the analyzed fuels, by means of 0D chemical kinetic simulations using a constant pressure reactor approach. Numerical results were compared to a database of experimental measurements collected from literature. The sooting tendency threshold dependency on equivalence ratio was also investigated and the results showed that the ethanol is the less sooting among the examined fuels, while the non-oxygenated gasoline exhibited the highest soot mass and Particle Number. This paper provides a CFD-based benchmark for soot mass and Particle Number for three fuel types with largely different chemical nature.
Assessment of late pilot injection effect in dual-fuel combustion
Authors: Caricato Antonio , Carlucci Antonio Paolo , Ficarella Antonio , Strafella Luciano
Published: October 2020

In this paper, the effect of late injection on combustion and emission levels has been investigated on a single cylinder compression ignition engine operated in dual-fuel mode injecting methane along the intake duct and igniting it through a pilot fuel injected directly into the combustion chamber. During the tests, the amount of pilot fuel injected per cycle has been kept constant, while the amount of methane has been varied on three levels. Therefore, three levels of engine load have been tested, while speed has been kept constant equal to 1500rpm. Pilot injection pressure has been varied on three set points, namely 500, 1000 and 1500 bar. For each engine load and injection pressure, pilot injection timing has been swept on a very broad range of values, spanning from very advanced to very late values. The analysis of heat release rate indicates that MK-like conditions are established in dual-fuel mode with late pilot injection. In these conditions, pollutant species, and NOx levels in particular, are significantly reduced without penalization – and in several conditions with improvement – on fuel conversion efficiency.
Development of a Combustion Delay Model in the Control of Innovative Combustions
Authors: Abbondanza Marco , Cavina Nicolò , Corti Enrico , Moro Davide , Ponti Fabrizio , Ravaglioli Vittorio
Published: October 2020

In modern internal combustion engines the research for innovative solutions aimed at the simultaneous reduction of engine-out pollutants and fuel consumption requires synergies from different application areas: the thermo-fluid dynamic design of the combustion chamber, the study and production of specific components for air and fuel supply, the development of sensors and related methods of analyzing their signals to control the combustion process. The most promising innovative combustion methodologies suitable to achieve high efficiency and low emissions, commonly named Low Temperature Combustions (LTC), usually require sophisticated techniques for the management of the combustion phase. With respect to the combustion angular position control, directly performed in traditional spark ignition engines through the ignition from the spark plug and in compression ignition engines by the timing of fuel injection, the ignition mechanisms of LTC combustions are characterized by a high sensitivity to the thermal conditions of the combustion chamber which greatly modifies the angular position of the combustion, mainly due to the combination of high ignition delays and lean homogeneous mixture. Once the hardware of the air and fuel supply systems has been defined, it is therefore essential to ensure the correct management of the combustion phase.

In this paper a model for the estimation of the delay between the start of injection and the start of combustion is presented. The model has been developed analyzing the experimental data from a modified cylinder of a diesel engine, fueled with gasoline, while the other three cylinders were still running with Diesel fuel. This solution represents a first step that allows analyzing the behavior of the combustion of gasoline in a Diesel engine, with the final goal to inject gasoline in all the engine cylinders. In particular, the approach used is similar to the one already applied in a traditional turbocharged gasoline engine, where the goal was to estimate the time delay between the spark firing and the start of combustion, mainly to detect the presence of undesired pre-ignition due to the presence of hot spots related to slightly knocking conditions. As it is well known, the role of the pilot injection is to reduce the ignition delay of the main injection. However, to significantly accelerate the ignition of the fuel injected with the main injection, it is necessary to burn a sufficient quantity of the fuel injected by the pilot before the Top Dead Center position (TDC). The application of this model has to allow the implementation of a feed-forward control to stabilize the whole combustion process and achieve the best conversion efficiency from energy to work, taking into account the operational constraints that must be satisfied to guarantee the integrity of the engine and the compliance with the homologation rules.
Experimental and numerical analyses to improve the design of engine coolant pumps
Authors: Mariani Luigi , Di Bartolomeo Marco , Di Battista Davide , Cipollone Roberto , Fremondi Fabrizio , Roveglia Riccardo
Published: October 2020

In this paper, an experimentally based procedure is presented to re-orient the design point of the pump in order to minimize the energy absorbed during the homologation cycle or during any real driving one. During it, in fact, every benefit on the pump’s efficiency is appreciated and produces fuel consumption and CO2 reduction. The procedure takes the advantage from a dynamic test bench for coolant pump, realized and engineered at University of L’Aquila. It has been linked to a model-based methodology, which evaluates, according to a specified vehicle’s mission profile, the speed and load variation of the engine propelling the vehicle, and, therefore, the pump speed. The knowledge of the engine cooling circuit for closed and fully opened thermostat allows the calculation of the flow rates and pressure delivered in each time instant of the drive cycle. The speed-flow rate-pressure delivered pump profile has been reproduced on the bench, and all the relevant quantities have been measured: an exact evaluation of the scatter of the efficiency of the pump, the instantaneous power and the overall energy absorbed have been obtained. Results show how the pump efficiency is far from its Best Efficiency Point. This conclusion invited the Authors to reorient the design pump considering an operating condition, which has a greater occurrence among all the operating points characteristic of a drive cycle. Four pumps have been designed following this approach, showing a sensible reduction of the energy absorbed: this represents a key point also for pump electrification.
Optical and Energetic Investigation of an Advanced Corona Ignition System in a Pressure-Based Calorimeter
Authors: Cruccolini Valentino , Discepoli Gabriele , Ricci Federico , Grimaldi Carlo Nazareno , Di Giuseppe Alessio
Published: October 2020

In recent years, radio-frequency corona igniters have been extensively studied for their capability to ensure an effective ignition also in lean or diluted mixtures. Corona ignition is volumetric, with streamers coming from a star-shaped electrode. During the discharge, many radicals and excited species, able to speed up the combustion onset, are generated. At the same time, corona igniters are able to release a considerable amount of thermal energy inside the combustion chamber. The correct determination of such energy is crucial to evaluate the effectiveness of the ignition. In this work, corona discharge is experimentally evaluated inside an optical vessel. In this apparatus, the released thermal energy is measured by means of pressure-based calorimetry, and at the same time the natural luminosity of the streamers is recorded with a high-speed camera. The goal is to find a relationship between thermal energy release and streamers luminosity. Tests are performed using nitrogen as medium, at different pressure levels inside the vessel. The peak electrode voltage is varied to characterize the igniter behaviour in different operating conditions. The results of this work can be used to quantify the corona ignition capabilities to involve a wide amount of medium while releasing a high amount of thermal energy. A repeatability evaluation of streamer evolution is investigated as well.
Waste heat recovery from a heavy-duty natural gas engine by Organic Rankine Cycle
Authors: Mariani Antonio , Morrone Biagio , Prati Maria Vittoria , Unich Andrea
Published: October 2020

Waste heat recovery can be a key solution for improving the efficiency of energy conversion systems. Organic Rankine Cycles (ORC) are a consolidated technology for achieving such target, ensuring good efficiencies and flexibility. ORC systems have been mainly adopted for stationary applications, where the limitations of layout, size and weight are not stringent. In road transportation propulsion systems, the integration between the powertrain and the ORC system is difficult but still possible. The authors investigated an ORC system bottoming a spark ignited internal combustion engine (ICE) powering a public transport bus. The bus, fuelled by natural gas, was tested in real driving conditions. Exhaust gas mass flow rate and temperature have been measured for calculating the thermal power to be recovered in the ORC plant. The waste heat was then used as energy input in a model simulating the performance of an ORC system. The heat transfer between the exhaust gases and the ORC fluid is crucial for the ORC performance. For this reason, attention was paid to considering the interaction between hot fluid temperature and ORC maximum pressure. ORC performance in terms of real cycle efficiency and power produced were calculated considering n-Pentane as working fluid. The fuel consumption was reduced from 271.5 g/km to 261.4 g/km over the driving cycle, corresponding to 3.7% reduction.
An aerostatic pad with an internal pressure control
Authors: Lentini Luigi , Colombo Federico , Raparelli Terenziano , Trivella Andrea , Viktorov Vladimir
Published: October 2020

Because of their almost zero friction and wear, aerostatic pads are widely used in applications where very precise positioning is required. However, this kind of bearing suffers from poor damping and low specific stiffness. This paper presents a new compensation strategy to increase air pad stiffness. This method exploits a custom-built pneumatic valve which can be easily integrated with any commercial pad. The design and the working principle of the proposed system are described and studied with the aid of a lumped parameter model. The effectiveness of the proposed compensation is numerically and experimentally evaluated. The results demonstrate that the solution represents a good and cost-effective method to enhance the static stiffness of aerostatic pads.
Downstream Compensator: Innovative Systems, Modeling Analysis and Energy Optimization
Authors: Bonavolontà Antonella , Mesturini Davide , Dolcin Cesare , Marani Pietro , Frosina Emma , Senatore Adolfo
Published: October 2020

The Energy optimization is becoming fundamental in the Fluid Power world. University and industries are working hard to promote innovative and efficient ideas to optimize components that are the main cause of energy dissipation of ICE and recently Electric Off-Road vehicles. A new hydraulic layout based on the concept of “Downstream compensation” is introduced and then validated using real test data. Three architectures of this innovative Directional Control Valve are presented in this paper. The first idea of layout includes a compensator controlled by two pressure signals taken before and after the main spool of the hydraulic circuit. Thanks to its controlled stroke, this compensator diverts to a highpressure accumulator part of flow that otherwise would be delivered to the tank. Moreover, two different layouts able to satisfy the Flow Sharing characteristic were developed. In any configuration, the compensator, thanks to its downstream position, allows to control the return flow, realizing a remarkable energy recovery from the overrunning loads and the simultaneous use of multiple actuators at different pressure levels.

For all the analyzed hydraulic circuit, lumped parameter models were realized, using a commercial software. These models, validated with experimental tests, have allowed to calculate the energy recovery achieved by the system. Moreover, an optimization of the most important system’s parameters and components were realized to improve the system efficiency. In every tested configuration, this compensator ensures great advantages for both the energy recovery and the economic point of view. Finally, an outlook is drawn of the reuse of recovered flow through the application of an electrohydraulic motor.
Feasibility study of using amplified piezo-stack actuators for the actuation of direct drive servovalves
Authors: Tamburrano Paolo , De Palma Pietro , Plummer Andrew R. , Distaso Elia , Amirante Riccardo
Published: October 2020

In this paper, we investigate the idea of using, in place of recent linear force motors, amplified piezo-stack actuators for the actuation of direct drive servovalves, in order to exploit the fast response of piezoelements accompanied by the increased displacement ensured by mechanical amplification systems. Some possible architectures are proposed in this paper for the direct actuation of four-way three-position (4/3) servovalves using one or two commercially available amplified piezo-stack actuators having a diamond amplification mechanism. The simplest architecture, which employs only one actuator, is assessed using wellestablished equations implemented in Simulink, allowing the hydraulic, mechanical and electrical parts of the valve to be accurately simulated. Three spools of different size are considered in the simulations in order to obtain performance predictions for different valve flow ratings. From the analysis of the inherent characteristics of the amplified piezo-stack and from the results of the simulations, advantages and disadvantages of this possible architecture are drawn and discussed in detail. Among the advantages, there are the simplicity of construction and the high potential in terms of step response speed and frequency response; the large dimensions, low chip shear force capability and high costs are the main disadvantages.
Simulink Modelling For Simulating Intensive Care Mechanical Ventilators
Authors: Tamburrano Paolo , De Palma Pietro , Plummer Andrew R. , Distaso Elia , Amirante Riccardo
Published: October 2020

This paper proposes a modelling approach for simulating mechanical ventilators for intensive care units (ICUs). The shortage of ventilators during the coronavirus disease 2019 (COVID-19) pandemic has focused attention on their design and performance. The proposed modelling approach consists in using the Mathworks®Simulink software tool and the SimScape Fluids (gas) library, so as to use well-established subroutines to simulate all the pneumatic components of typical ventilators for ICUs, such as the pressure reducing valves, pressure relief valves, check valves, tanks, ON\OFF and proportional directional valves, etc. The patient is simulated by setting the values of lung compliance and pressure losses occurring in the trachea. The proposed modelling approach is used in this paper to simulate a pneumatic scheme employed in some commercial ventilators. The model allows a very accurate prediction of fundamental parameters, such as the inspiratory flow rate, the inspiratory pressure, the end-expiratory pressure. Since the software interface is user-friendly, it can easily be used by manufacturers to correctly choose the geometrical and operating parameters of the components during the design stage or to assess different scenarios.
Stability analysis of a pneumatically actuated inverted pendulum
Authors: Colombo Federico , Mazza Luigi , Pepe Giuseppe , Raparelli Terenziano , Trivella Andrea
Published: October 2020

This paper deals with the stabilization of an inverted pendulum on cart; the latter is pneumatically actuated by a double acting cylinder controlled by low cost proportional valves. In particular, a numerical model of whole system is developed in order to find the ability of the pneumatic actuation in stabilizing the pendulum and evaluate its bandwidth. A cascade of two control loops (the inner one for the pendulum angle, the outer one for the cart displacement) are analyzed and proper compensators are defined. The possibility of introducing an additional loop to control the force exerted by the actuator on the cart is evaluated.
Adsorption gas Heat Pump fuelled with hydrogen enriched natural gas blends: the analytical simulation model development and validation
Authors: Sforzini Matteo , Lo Basso Gianluigi , Paiolo Romano , De Santoli Livio , Cumo Fabrizio
Published: October 2020

This study deals with the implementation of an analytical model to simulate the energy performance associated to a commercial Gas adsorption Heat Pump, when H2NG (Hydrogen Enriched Natural Gas) blends are used as fuel. In detail, a water source heat pump manufactured by Robur (GAHP-WS) has been used as a reference device for building the simulation model within the MATLAB-Simulink environment. Thereafter, the simulation results have been validated by the experimental campaign, testing on field and in actual operating conditions the heat pump. Specifically, the model has been developed by implementing the WaterAmmonia mass and energy balances for each component. It is able to evaluate fuel consumption, efficiency in terms of GUE, required thermal power from the cold heat sink as well as the water outlet temperature at the evaporator, once the heating load is used as the main input. The experimental campaign for the model calibration and validation has been carried out over the winter season. Additionally, the heat pump performance has been detected when it operates to supply hot water at 60 °C and 55 °C, and it is fuelled with growing hydrogen fractions, starting from 0% vol., 5% vol. up to 10% vol. In the end, the standard errors as well as the relative ones affecting the main output parameters have computed for the validation process. From the outcomes it emerges that the average relative standard error related to all load conditions is lower than 2.5% for natural gas operation. On the contrary, it ranges between 2.5% and 4% when H2NG at 5% and 10% by volume have been burnt.
An Experimental Investigation on Energy Performance of The Hybrid Photovoltaic Thermal System
Authors: Barati Shahrokh , de Santoli Livio , Lo Basso Gianluigi , Galizia Antonio , Spiridigliozzi Giulia
Published: October 2020

Climate change is a worldwide recognized problem, and its mitigation identified as one of the most significant challenges. The way to achieve this purpose is to reduce greenhouse gases (GHG) emissions through the energy system using renewables. The change from an energy system based on fossil fuels to renewable sources-based one is necessary on which the world community agrees. A photovoltaic thermal (PV/T) panel is a system that can produce both electricity and thermal energy simultaneously in one integrated system. This paper deals with hybrid energy systems, specifically a hybrid system to produce power and thermal energy from solar sources consisting of photovoltaic thermal modules. The hybrid system consists of 7 hybrid photovoltaic panels installed on the roof of the laboratory. This paper presents a study for experimental data obtained from a measurement campaign of the thermal and electrical behavior of a PV/T system in single and series models.
Ducted Savonius Turbine Performance: A Multi-Application Approach
Authors: Brusca Sebastian , Famoso Fabio , Galvagno Antonio , Lanzafame Rosario , Mauro Stefano , Messina Michele , Prestipino Mauro
Published: October 2020

In the last decades, the public opinion has paid great attention to environmental pollution and global warming. Energy sector has a strong impact on environment. Thus, the use of renewable energies is becoming mandatory. The present paper deals with a study of ducted Savonius turbine performance as a function of geometric and operating parameters. Ducted turbines could be used as power take-off in multiple applications. In this paper, two main applications were studied. The first application is related to the possibility to install the turbine inside building with the purpose of architectonic integration of the system. The second one is related to wave energy harvesting. In both cases the same type of turbine was used to convert input energy (wind or wave energy) into electricity. Turbine performance were studied as a function of turbine overlap ratio, as well as air flux oscillating frequencies. On the basis of the obtained results, turbine performance increase in ducted configuration and a change in best overlap ratio was registered.
Experimental characterization of the unsteady performance behavior of a Wells turbine operating at high flow rate coefficients
Authors: Torresi Marco , Stefanizzi Michele , Gurnari Luana , Filianoti Pasquale G. F. , Camporeale Sergio M.
Published: October 2020

Even if researchers are working on the exploitation of marine energy for more than thirty years, blue energy is not yet a consolidated reality and still contributes marginally to the world energy mix. For this reason, in the last years, the effort of the scientific community has been significantly intensified to further improve the know-how on marine energy harvesting. The goal is to allow ocean energy to effectively contribute to a more sustainable energy production in the next future. In the wide range of technologies for wave energy harvesting, Oscillating Water Column (OWC) devices are counted among of the most mature ones. Due to the oscillating nature of the generated air flow, which continuously inverts its direction, OWC devices need to be coupled with self-rectifying turbines, such as Wells, impulse, or biradial turbines. Wells turbines can reach high efficiencies, but their performance can show a hysteretic behaviour due to dynamic stall phenomena, especially in presence of high amplitude flow rate oscillations. Moreover, under dynamic stall conditions, during the flow deceleration, the shaft torque evidence the presence of gradually damped fluctuations, which delay the flow reattachment, superposed to the hysteresys loop. In order to better characterize this phenomenon, a new experimental campaign was performed in the open wind tunnel of the Polytechnic University of Bari on a 3D-printed Wells turbine model. The interest is mainly focused on the dependency of these torque fluctuations on the amplitude and frequency of the oscillating flow.
Food waste anaerobic digestion in Umbria region (Italy): scenario analysis on the use of digestate through LCA
Authors: Bartocci Pietro , Zampilli Mauro , Massoli Sara , Fantozzi Francesco
Published: October 2020

The project irexfo LIFE16 deals mainly with food waste and expired food prevention and reduction, but also with its valorization in biogas plants. Due to legal aspects the cycle of food waste needs to be closed returning the anaerobic digestate to the soil and so providing fertilizer for the cultivation and production of new crops. This is not possible at the moment in Italy because of the Decree of the 25th February 2016 on the disposal of digestate produced from raw materials which are not considered biomasses. The EU Regulation of 2019/1009 of the European Parliament and of the council of the 5th of June 2019, identifies some Component Materials Categories (CMCs), which can be considered as fertilizers; among them we find digestate other than fresh crop digestate, which includes digestate produced from bio-waste and another category on food industry wastes. For this reason, it is meaningful to compare the two possible alternatives: use of food waste digestate as it is in the field and use of food waste digestate after composting it (as currently required by the Italian law).