bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of multi-vinyl taxogen dimensions on high molecular weight soluble polymer synthesis using transfer-dominated branching radical telomerisation
Authors: Penrhyn-Lowe Oliver B. , Flynn Sean , Cassin Savannah R. , Mckeating Samuel , Lomas Sarah , Wright Stephen , Chambon Pierre , Rannard Steve P.
Published: October 2021

The creation of branched polymers by TBRT is influenced by the molecular dimensions of the polymerising species. A mechanistic understanding is presented that includes a radical lifetime sphere model that is unique to telomerisation conditions used.
Advances in Pd-catalyzed C–C bond formation in carbohydrates and their applications in the synthesis of natural products and medicinally relevant molecules
Authors: Hussain Nazar , Hussain Altaf
Published: October 2021

This review highlights the recent progress of Pd-catalyzed reactions in carbohydrates. Different types strategies and applications in the synthesis of natural products, SGLT2 inhibitors and biologically active have been included in this review.
Collective motion of run-and-tumble repulsive and attractive particles in one-dimensional systems
Authors: Gutiérrez C. Miguel Barriuso , Vanhille-Campos Christian , Alarcón Francisco , Pagonabarraga Ignacio , Brito Ricardo , Valeriani Chantal
Published: October 2021

Aggregation of run and tumble particles in one dimension with repulsive and attractive interactions.
A critical discussion on the analysis of buried interfaces in Li solid-state batteries. Ex situ and in situ/operando studies
Authors: López Isidoro , Morey Julien , Ledeuil Jean Bernard , Madec Lénaïc , Martinez Hervé
Published: October 2021

Rigorous approaches to study electro-chemo-mechanical processes at the analytically challenging buried interfaces in solid-state batteries are discussed. Furthermore, new experiments evidence potential misinterpretations in depth-profiling studies.
3D atomic imaging of low-coordinated active sites in solid-state dealloyed hierarchical nanoporous gold
Authors: Wang Chunyang , Liu Hongyang , Duan Huichao , Li Zhenwei , Zeng Panlin , Zou Peichao , Wang Xuelu , Ye Hengqiang , Xin Huolin L. , Du Kui
Published: October 2021

3D imaging of low-coordinated atoms in nanoporous metal by atomic-resolution electron tomography.
Multifunctionality of prostatic acid phosphatase in prostate cancer pathogenesis
Authors: Alpert Evgenia , Akhavan Armin , Gruzman Arie , Hansen William J. , Lehrer-Graiwer Joshua , Hall Steven C. , Johansen Eric , McAllister Sean , Gulati Mittul , Lin Ming-Fong , Lingappa Vishwanath R.
Published: October 2021

The role of human prostatic acid phosphatase (PAcP, P15309|PPAP_HUMAN) in prostate cancer was investigated using a new proteomics tool termed signal sequence swapping (replacement of domains from the native cleaved amino terminal signal sequence of secretory/membrane proteins with corresponding regions of functionally distinct signal sequence subtypes). This manipulation preferentially redirects proteins to different pathways of biogenesis at the endoplasmic reticulum (ER), magnifying normally difficult to detect subsets of the protein of interest. For PAcP, this technique reveals three forms identical in amino acid sequence but profoundly different in physiological functions, subcellular location, and biochemical properties. These three forms of PAcP can also occur with the wildtype PAcP signal sequence. Clinical specimens from patients with prostate cancer demonstrate that one form, termed PLPAcP, correlates with early prostate cancer. These findings confirm the analytical power of this method, implicate PLPAcP in prostate cancer pathogenesis, and suggest novel anticancer therapeutic strategies.
Xbp1s-Ddit3 promotes MCT-induced pulmonary hypertension
Authors: Jiang Hongxia , Ding Dandan , He Yuanzhou , Li Xiaochen , Xu Yongjian , Liu Xiansheng
Published: October 2021

Pulmonary hypertension (PH) is a life-threatening disease characterized by vascular remodeling. Exploring new therapy target is urgent. The purpose of the present study is to investigate whether and how spliced x-box binding protein 1 (xbp1s), a key component of endoplasmic reticulum stress (ERS), contributes to the pathogenesis of PH. Forty male SD rats were randomly assigned to four groups: Control, Monocrotaline (MCT), MCT+AAV-CTL (control), and MCT+AAV-xbp1s. The xbp1s protein levels were found to be elevated in lung tissues of the MCT group. Intratracheal injection of adeno-associated virus serotype 1 carrying xbp1s shRNA (AAV-xbp1s) to knock down the expression of xbp1s effectively ameliorated the MCT-induced elevation of right ventricular systolic pressure (RVSP), total pulmonary resistance (TPR), right ventricular hypertrophy and medial wall thickness of muscularized distal pulmonary arterioles. The abnormally increased positive staining rates of proliferating cell nuclear antigen (PCNA) and Ki67 and decreased positive staining rates of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) in pulmonary arterioles were also reversed in the MCT+AAV-xbp1s group. For mechanistic exploration, bioinformatics prediction of the protein network was performed on the STRING database, and further verification was performed by qRT-PCR, Western blots and co-immunoprecipitation (Co-IP). DNA damage-inducible transcript 3 (Ddit3) was identified as a downstream protein that interacted with xbp1s. Overexpression of Ddit3 restored the decreased proliferation, migration and cell viability caused by silencing of xbp1s. The protein level of Ddit3 was also highly consistent with xbp1s in the animal model. Taken together, our study demonstrated that xbp1s-Ddit3 may be a potential target to interfere with vascular remodeling in PH.
The outermost stellar halo of NGC 5128 (Centaurus A): Radial structure
Authors: Rejkuba M. , Harris W. E. , Greggio L. , Crnojević D. , Harris G. L. H.
Published: October 2021

Context.The extended stellar halos of galaxies contain important clues for investigating their assembly history and evolution.

Aims.We investigate the resolved stellar content and the extended halo of NGC 5128 as a function of galactocentric distance, and trace the halo outward to its currently detectable limits.

Methods.We usedHubbleSpace Telescope images obtained with the WFPC2, ACS, and WFC3 cameras equipped withF606WandF814Wfilters to resolve individual red giant branch (RGB) stars in 28 independent pointings across the halo of NGC 5128. The stellar halo analysis for 14 of these pointings is presented here for the first time. Star counts from deepVIcolor-magnitude diagrams reaching at least 1.5 mag below the tip of the RGB are used to derive the surface density distribution of the halo. The contamination by Milky Way stars is assessed with a new control field, with models, and by combining optical and near-IR photometry.

Results.We present a new calibration of the WFC3F606W + F814Wphotometry to the ground-basedVIphotometric system. The photometry shows that the stellar halo of NGC 5128 is dominated by old RGB stars that are present in all fields. TheV-band surface brightness of fields changes from 23 to 32 mag arcsec−2between the innermost field only 8.3 kpc from the galaxy center to our outermost halo fields, which are located 140 kpc away from the center along the major axis and 92 kpc along the minor axis. Within the inner ∼30 kpc, we also find evidence for a 2 − 3 Gyr old population traced by asymptotic giant branch stars that are brighter than the tip of the RGB. This population contributes only up to 10% in total stellar mass if it is 2 Gyr old, but a larger fraction of 30 − 40% is required if its age is 3 Gyr. The stellar surface density profile is well fit by a classicr1/4curve or a simple power-law form ∼r−3.1over the full radial range, with no obvious break in the slope, but with large field-to-field scatter. The ellipticity measured from integrated-light photometry in the inner parts,e = (b/a) = 0.77, flattens toe = 0.54 ± 0.02 beyond 30 kpc. Considering the flattening of the outer halo, the projection of the elliptical isophote on the semimajor axis for our most distant field reaches nearly 30 effective radii.
Transient obscuration event captured in NGC 3227
Authors: Wang Yijun , Kaastra Jelle , Mehdipour Missagh , Mao Junjie , Costantini Elisa , Kriss Gerard A. , Pinto Ciro , Ponti Gabriele , Behar Ehud , Bianchi Stefano , Branduardi-Raymont Graziella , De Marco Barbara , Grafton-Waters Sam , Petrucci Pierre-Olivier , Ebrero Jacobo , Walton Dominic James , Kaspi Shai , Xue Yongquan , Paltani Stéphane , di Gesu Laura , He Zhicheng
Published: October 2021

The relationship between warm absorber (WA) outflows of active galactic nuclei and nuclear obscuration activities caused by optically thick clouds (obscurers) crossing the line of sight is still unclear. NGC 3227 is a suitable target for studying the properties of both WAs and obscurers because it matches the following selection criteria: WAs in both ultraviolet (UV) and X-rays, suitably variable, bright in UV and X-rays, and adequate archival spectra for making comparisons with the obscured spectra. In the aim of investigating WAs and obscurers of NGC 3227 in detail, we used a broadband spectral-energy-distribution model that is built in findings of the first paper in our series together with the photoionization code of SPEX software to fit the archival observational data taken by XMM-Newton and NuSTAR in 2006 and 2016. Using unobscured observations, we find four WA components with different ionization states (log ξ [erg cm s−1] ∼ −1.0, 2.0, 2.5, 3.0). The highest-ionization WA component has a much higher hydrogen column density (∼1022 cm−2) than the other three components (∼1021 cm−2). The outflow velocities of these WAs range from 100 to 1300 km s−1, and show a positive correlation with the ionization parameter. These WA components are estimated to be distributed from the outer region of the broad line region (BLR) to the narrow line region. It is worth noting that we find an X-ray obscuration event in the beginning of the 2006 observation, which was missed by previous studies. We find that it can be explained by a single obscurer component. We also study the previously published obscuration event captured in one observation in 2016, which needs two obscurer components to fit the spectrum. A high-ionization obscurer component (log ξ ∼ 2.80; covering factor Cf ∼ 30%) only appears in the 2016 observation, which has a high column density (∼1023 cm−2). A low-ionization obscurer component (log ξ ∼ 1.0 − 1.9; Cf ∼ 20%−50%) exists in both 2006 and 2016 observations, which has a lower column density (∼1022 cm−2). These obscurer components are estimated to reside within the BLR by their crossing time of transverse motions. The obscurers of NGC 3227 are closer to the center and have larger number densities than the WAs, which indicate that the WAs and obscurers might have different origins.
Development of benchmark scenarios for sector coupling in the Italian national energy system for 100% RES supply to power and mobility
Authors: Colbertaldo Paolo , Guandalini Giulio , Campanari Stefano
Published: October 2021

The urgence of decarbonization has pushed many countries to set ambitious net-zero CO2 emission targets by 2050. This requires a substantial transformation of energy sources, conversion methods, and final uses. This work investigates the structure of the future Italian energy system – in terms of power generation capacity, energy storage, mobility fuel shares – and assesses benchmark scenarios able to reach a fully decarbonized supply in power and transport sectors, considering their long-term evolution. The analysis adopts a multi-node multi-vector model that simulates the year-long energy system behaviour with hourly time resolution and optimizes sizing (installed capacities) and operation (energy flows). The model considers power generation from different sources, electric consumption, and mobility demand for energy vectors, focusing on electricity and hydrogen. The required installed capacities of RES power plants and energy storage systems appear to be extremely high (at least 10x today’s solar PV or more), but in general positively influenced by sector integration strategies and energy vector multiplicity. Energy storage and flexibility solutions are essential, combining battery storage, Power-to-Hydrogen, Power-to-Power, smart charging, and vehicle-to-grid. If capacity installation is limited (e.g., due to land availability), the need to satisfy consumption yields significant import requirements, which also depend upon the mobility mix and the decarbonization targets.
Methodology and Simulation of Electrical Grid Peak Shaving Strategy based on Photovoltaic and Storage Optimization: an Italian Residential Sector Case Study
Authors: Cimaglia Jacopo , Romano Sabrina , Mancini Francesco
Published: October 2021

The European Union has set some ambitious targets to reach the goal of net-zero greenhouse gasses by 2050. The outlined scenarios provide the use of Renewable Energy Sources (RES) on a large-scale, but to do so, different kinds of actions must be taken, because the ample amount of non-programmable electricity sources may cause grid management problems and a mismatch in the energy supply and demand. The vast increase of the Italian power demand, which typically occurs in the evening, necessarily requires a rapid increase in thermoelectric power generation. A possible solution to avoid this phenomenon is the optimization of photovoltaic production and storage and, simultaneously, the minimization of the Life-Cycle impact of these systems on the environment.

This work aims to identify a methodology that supports the analysis and design of a production, self-consumption and storage system, which services a residential user aggregate, in order to reach an electric power demand optimization. In particular, the target is to obtain a Peak Shaving of the electrical demand power curve, by setting a limit on the maximum absorption of power from the grid, and supplying the rest of the user’s power needs through an electrical energy storage system, charged from the photovoltaic plant during the daily overproduction time.

To do so, 14 dwelling power consumptions have been aggregated and analysed, starting from a data monitoring that occurred in January and June of 2019. The energy consumptions considered, are in line with the Italian average ones.

The Peak Shaving strategy effectiveness has been evaluated by using a percentage parameter, that represents the number of power absorption peaks from the grid, avoided thanks to the storage system. In this study, some optimal system plant settings, in terms of maximum power absorption from the grid, photovoltaic nominal peak power and electrical storage capacity, are investigated to reach the set goals, and some solutions are presented, in light of the needs of the public grid where the system operates.
Multi-objective sensitivity analysis of shell-and-tube LHTES performance
Authors: Fornarelli Francesco , Dambrosio Lorenzo
Published: October 2021

In the present paper a sensitivity analysis has been carried out concerning the charging/discharging time and the stored energy performances of a shell-and-tube LHTES with respect to the number of tubes and the tube internal radius. The aim of this analysis is to investigate how the design variables affect the LHTES performance. this could lead to determine the thermal storage optimal design. Thus, the sensitivity analysis has a key role in the selection of several acceptable solutions. The consideredLHTESexhibits a cylindrical shell geometry characterized by constant height and diameter. This aspect has allowed to employ simplified theoretical models able to predict the charging/discharging time and the stored energy performance. These models consider a constant heat exchange wall temperature whereas the heat exchange area and the wholePCMvolume vary according to the design variables. This analysis represents the first step to solve the multi-objective optimization of the thermal storage design problem and then to determine the best solutions in both design variables and thermal storage performance domains.
Sizing and operation of energy storage by Power-to-Gas and Underwater Compressed Air systems applied to offshore wind power generation
Authors: Crespi Elena , Mammoliti Luca , Colbertaldo Paolo , Silva Paolo , Guandalini Giulio
Published: October 2021

Among the possible solutions for large-scale renewable energy storage, Power-to-Gas (P2G) and Compressed Air Energy Storage (CAES) appear very promising. In this work, P2G and an innovative type of CAES based on underwater storage volumes (UW-CAES) are compared from a techno-economic point of view, when applied in combination with a 48 MWe offshore wind power plant, selecting an appropriate location for both high productivity and favorable seabed depth. An optimization model is employed to study the system design and operation, maximizing the lifetime plant profitability, while considering differential installation and operation costs, market values of the products (i.e., hydrogen and electricity), and technological constraints. In the current economic and technological scenario, the resulting P2G system has a nominal power equivalent to about 10% of the wind park capacity, with a small hydrogen storage buffer. On the other hand, the compressor and the turbine of the UWCAES have a nominal power close to the full wind farm capacity, and large underwater compressed air tanks are required. Both options significantly impact the wind plant management but the most beneficial applications of the two systems are different: the P2G results in a compact and flexible unit, whereas the UW-CAES is able to exploit a higher average conversion efficiency (about 80% round-trip) against a much higher installed power and investment cost. Anyway, considering the current framework, the resulting economics are still inadequate, but their competitiveness can improve compatible with the expected evolution of energy markets in the next future.
A methodological approach for energy demand assessment: theoretical analysis on solar thermal collector energy contribution
Authors: Palladino Domenico , Lavinia Carmen , Margiotta Francesca , Pagliaro Francesca
Published: October 2021

Solar thermal collector system is a widely used solution involving renewable energy source to cover the energy demand for domestic hot water production. At Italian level, the UNI TS 11300 provides a calculation methodology based on two approaches: the asset rating, which is easy to be applied but provides approximated results, and the tailored rating, which is more reliable but requires several detailed information. In this context, the present work proposes a new methodological approach to develop a simplified calculation method in order to obtain accurate energy performance results with no-additional cost for assessors and final users. Different case studies were analysed carrying out parametric simulations. The obtained results have led to the definition of the new simplified calculation methodology to predict the thermal energy supplied by solar thermal collectors; it allows also calculating the domestic hot water volume to be covered by other technical building systems, becoming a useful tool for their pre-dimensioning. Besides, the results open to new scenarios of interest, such as the application of the same approach to other energy services in order to integrate the outcomes of the asset rating provided by the UNI TS 11300.
Refurbishment and electrification in the hotel sector: four hotels in the historic centre of Rome
Authors: Romano Giada , Mancini Francesco
Published: October 2021

According to the European Renovation Wave, the European building stock is obsolete and changes very slowly: more than 220 million housing units and 85-95% of the existing buildings will still be in use in 2050 and are absolutely not energy efficient. To cut emissions by 55% by 2030, the EU should reduce greenhouse gas emissions from buildings by 60%, their final energy consumption by 14% and energy consumption for heating and cooling by 18%. It is therefore urgent for the EU to focus on making buildings more energy efficient, less carbon intensive throughout their life cycle and more sustainable. From this framework comes the need for an adaptation not only of residential buildings but also of hotel facilities, which, on a national scale, make up about 45% of the accommodation facilities. In particular, the offer of accommodation facilities must be constantly adequate and the structures must be upgraded so that they always remain usable and comply with current regulations from the accessibility, seismic-structural and energy point of view. In this research, four hotels located in the historic centre of Rome have been analysed as case studies. Starting from an analysis of the current state, a series of interventions on the building envelope and systems have been studied, evaluating energy savings and the reduction of polluting emissions. With regard to the systems, the total electrification of the heating and domestic hot water preparation systems has been hypothesised, with the introduction of storage systems, also in view of participation in Demand Response programs.
Thermal enhancement of windows performance by means of innovative technologies
Authors: Cannavale Alessandro , Carlucci Francesco , Fiorito Francesco , Martellotta Francesco , Ayr Ubaldo , Berardi Umberto
Published: October 2021

Thermal performances of window frames and glazing represent a field of growing research efforts - worldwide - aiming to reduce energy consumption and achieve indoor comfort. A combination of newly designed super-insulated window frames and innovative glazing technologies may enhance the performance of windows. Aerogel-based “thermal breaks” for window frames, coupled with high-performing glazing, may lead to significant energy saving. In this work, yearly energy use for heating and cooling were assessed in several locations, for building models equipped with innovative technologies, for glazing and frames. The results of numerical simulations confirmed the opportunities offered by new technologies.
Numerical investigation on latent thermal energy storage in shell and corrugated internal tube with PCM and metal foam
Authors: Buonomo Bernardo , Di Somma Francescantonio , Manca Oronzio , Nardini Sergio , Plomitallo Renato Elpidio
Published: October 2021

A numerical investigation on Latent Heat Thermal Energy Storage System (LHTESS) based on an aluminum foam totally filled with phase change material (PCM) is accomplished. The PCM used is a pure paraffin wax with melting over a range of temperature and a high latent heat of fusion. The LHTESS geometry under investigation is a vertical shell and tube. The corrugated internal surface of the hollow cylinder is assumed at a constant temperature above the PCM melting temperature. The other external surfaces are assumed adiabatic. The paraffin wax phase change process is modelled with the enthalpy-porosity theory, while the metal foam is considered as a porous media obeying to the Darcy-Forchheimer law. Local thermal non-equilibrium (LTNE) model is assumed to analyze the heat transfer in the metal foam. The governing equations are solved employing the Ansys-Fluent code. The numerical simulations results, reported as a function of time, and concerning the LHTESS charging phase, are compared in terms of melting time, average temperature and energy storage rate. The corrugated internal surface effect is analyzed with respect to the wavelength and wave amplitude of the corrugation.
Development of an experimental apparatus and a data analysis protocol for the test of hydrogen volume and flow meters in controlled environmental conditions
Authors: Battistella Francesco , Ravidà Antonino , Mastromatteo Massimo , Pinna Roberto Simone , Valenti Gianluca
Published: October 2021

The decarbonization of the residential sector is fundamental for energy transition. In this context, it is promising the introduction of hydrogen in natural gas networks in specific hydrogen districts. Accordingly, hydrogen meters are needed for accounting the fuel consumptions. The topic of this work is the development and construction of an experimental apparatus for testing safely hydrogen volume and flow meters up to 24 m3/h (referred to standard conditions) in controlled environmental conditions, between -25 and +55 °C (and beyond). The apparatus realized can test up to four volume and flow meters in a climatic chamber while processing air or pure hydrogen or methane. Methane-hydrogen mixtures can be tested connecting simply bottles with synthetic blends. The aim is to verify the measurement accuracy of the meters under test. A dedicated data analysis protocol featuring statistical process control is developed to monitor the stability of the system during the test. It exploits statistical indicators representing the autocorrelation, the normality of residuals of the mean value and the lag plot. The apparatus is realized, and it complies with the leakage limits set by indications in literature. A new ultrasonic domestic meter is tested in the apparatus. It has been developed by Pietro Fiorentini S.p.A. in the framework of the Hy4Heat project. Its error trends measured at all temperatures comply with the limit of 3.5% between 0.12 and 2 m3/h and 2% between 2 and 20 m3/h, as imposed by legislations.
Modeling the motion of a Taylor bubble in a microchannel through a shear-thinning fluid
Authors: Aquino Andrea , Picchi Davide , Poesio Pietro
Published: October 2021

Applications of multiphase flows in microchannels as chemical and biological reactors and cooling systems for microelectronic devices typically present liquid slugs alternated with bubbles of elongated shape, the Taylor bubbles. These occupy almost entirely the cross-section of the channel and present a hemispherical front and a liquid layer, the lubrication film, which separates the gas from the tube wall. The Taylor bubble perturbs the surrounding fluids activating many transport mechanisms in the proximity of the gas-liquid interface; therefore, the bubble motion significantly influences the heat and mass transfer rates. Although many works deeply investigate the bubble hydrodynamics in Newtonian fluids, the knowledge about the relation between bubble hydrodynamics and rheological properties is insufficient, and studies where the continuous phase exhibits a shear-thinning behavior are missing. Our numerical analysis tries to fill this gap by investigating the motion of a Taylor bubble in a non-Newtonian shear-thinning fluid, modeled by the Carreau viscosity model. First, we validate the results against the Newtonian case and a recent theory for shear-thinning fluids (Picchi et al., Journal of Fluid Mechanics, 2021, 918). Then, we investigate the bubble hydrodynamics far from the validity range of the current models. Finally, we study the scaling of the bubble velocity and lubrication film thickness, extending the current theory to shear-thinning fluids.
Study and optimization of a parallel hydraulic hybrid system for heavy vehicles
Authors: Di Lorenzo Camilla , Andretta Nicola , Rossetti Antonio , Macor Alarico
Published: October 2021

The parallel hydraulic hybridization, thanks to its simplicity and high specific power, is a suitable solution for the retrofitting of off-highway vehicles subject to work cycles with frequent stop-and-go. This work is focused on the potential of the low-cost parallel hybrid solutions, i.e. characterized by current-technology components, for a specific class of heavy vehicles: city buses. After functional sizing, the hybrid vehicle was modelled and simulated in the Amesim environment. The comparison with the non-hybridized reference vehicle highlighted an interesting consumption reduction, which in any case varies with the type of route. Finally, an optimization of the hybrid vehicle was carried out by means of genetic algorithms, which led to a further, and not negligible, consumption reduction compared to the hybridized version. Optimization, therefore, can be seen as a tool to overcome those minimum benefit thresholds that manufacturers consider as necessary for the industrialization and marketing of new energy recovery systems.
Energy, environmental and economic analysis of electric vapour compression and gas driven absorption heat pumps for single-family houses
Authors: Villa Giorgio , Scoccia Rossano , Toppi Tommaso , Aprile Marcello
Published: October 2021

The aim of this paper is to compare energy consumptions, CO2 emissions, and operative costs of condensing boilers, electric vapour compression heat pumps and gas driven absorption heat pumps to provide space heating and domestic hot water. The analysis is performed for 140 m2 single-family houses in five different Italian cities whose envelope features depend on the location. For each location, two different envelope conditions are considered. The first one is a non-insulated building, while the second one is the same building, but an external thermal insulation is added on vertical walls and roof. To avoid internal renovation, radiators are maintained as emission system. Combined dynamic simulations are performed to appreciate building and system interactions. A 6 second time step is set to evaluate properly interactions and the DHW profile demand. In addition, the GHP dynamic model is a grey box model experimentally validated. The results show that electric vapour compression heat pumps reach the highest non-renewable primary energy savings (>32%) compared to condensing boilers, but their operative costs are higher due to the higher specific cost of electricity in Italy. Gas driven absorption heat pumps achieve a lower consumption reduction than electric heat pumps (>22%), but they have also the minimum operative cost among the three technologies.
Modeling of an Organic Rankine Cycle Waste Heat Recovery system for automotive engine applications
Authors: D’Arco M. , Giardiello G. , Baratta M. , de Nola F. , Gimelli A. , Misul D.
Published: October 2021

The remarkable investments made by manufacturers over the last few decades have contributed to improving the performance of internal combustion engines in every aspect: lower polluting emissions, greater specific power and thermal efficiency. Despite this, on an average, about 40% of the thermal power theoretically available from the combustion of the fuel is still stored in the exhaust gases and therefore dispersed in the environment. In this work the modeling and validation of a waste heat recovery (WHR) plant will be described, combining the engine with a low temperature Organic Rankine Cycle (ORC) system, in order to investigate the feasibility of this system on board of a vehicle, analyzing the quantity of thermal power recovered and made available in the form of electrical power. The ORC plant is modeled using a 0D/1D thermo-fluid dynamic approach. Starting from experimental tests, a map-based model for the piston pump and the scroll expander has been developed. The model has been validated through the use of a vector optimization technique, exploiting a genetic algorithm (MOGA). Subsequently, this system has been coupled to a spark ignition engine for automotive applications, adapting its speed range to comply with the ORC experimental tests. To have an accurate control over the expander inlet temperature, a bypass circuit and two throttles actuated by a PI controller have been implemented. The simulations were performed by considering 18 engine points at maximum load and different rpm. An average thermal efficiency increase of the system of 2.6% was obtained by introducing the recovery plant, and wide improvement chance can be foreseen in the case of ORC full-power use.
On the optimal design of sliding rotary vane pump for heavy-duty engine cooling systems
Authors: Fatigati Fabio , Di Battista Davide , Di Bartolomeo Marco , Mariani Luigi , Cipollone Roberto
Published: October 2021

Presently the on-the-road transportation sector is responsible of the 21% of the whole CO2 amount emitted into atmosphere. This pushes the International Governments and Organizations to provide strict limitations in terms of ICEs emissions, also introducing fees payment for the car manufacturers. The vehicle electrification allows certainly to meet these requirements, but the higher cost and the need of a green electricity still limit a widespread diffusion among all social classes. Thus, the technological improvement of internal combustion engine plays a key role in the transition period. Among these technologies, the engine thermal management allows to achieve a good compromise between the CO2 emission reduction and related costs. It was demonstrated that replacing the conventional centrifugal pump of engine cooling system with a sliding vane rotary pump (SVRP), important benefits in terms of CO2 emission reduction can be achieved as centrifugal pump efficiency decreases significantly when the engine works far from the maximum load (i.e. design point of the pump). Nevertheless, the complex thermo-fluid-dynamic phenomena taking place inside a SVRP make its design not immediate, particularly if heavy duty ICE cooling systems are considered. These applications indeed are challenging due to the wide operating range and the huge flow rates which pump must deliver. These operating requirements make difficult the choice of the main design parameters: among the different ones, the pump revolution speed and displaced volume. In the present paper a design strategy is developed for this type of pumps based on a comprehensive mathematical model of the processes occurring, predicting volumetric, indicated and mechanical efficiencies. The model was validated with a wide experimental activity so acting as virtual development platform. The results show how the best global efficiency (0.59) is achieved adopting a dual axial intake port configuration, with a suitable choice result of a trade-off between displaced volume and revolution speed. The analysis also show that the pump keeps its efficiency close to the design one for a wide operating range which is particularly suitable for the cooling of an ICE.
Thermal Management Opportunity on Lubricant Oil to Reduce Fuel Consumption and Emissions of a Light-Duty Diesel Engine
Authors: Di Battista Davide , Fatigati Fabio , Di Bartolomeo Marco , Vittorini Diego , Cipollone Roberto
Published: October 2021

The high viscosity of the lubricant oil in internal combustion engines at cold starts is responsible for poor friction reduction and inadequate thermal stabilization of metallic masses and represents a major bottleneck in the efforts to reduce specific fuel consumption and pollutant emissions. Consequently, the possibility of integrating techniques for proper thermal management of the lubricant oil on internal combustion engines is of utmost importance to both homologation and daily on-road operation. Main options for reducing the warm-up time for the engine lubricant are the upgrade of the engine cooling and lubricating circuits, dedicated heating, different flow management of the oil/coolant heat exchanger, a renewed design of the oil sump or a thermal storage section to increase the oil temperature in the early phases of the warm up. The paper presents a new opportunity, using a hot storage medium to heat up the oil in the early phase of a driving cycle. A certain quantity of hot water, so, is stored in a tank, which can be used to warm up the lubricating oil when the engine is started up. The heating of this service water can be done by using exhaust gas heat, which is always wasted in the atmosphere. The activity is realized on an IVECO 3.0 L light-duty diesel engine, during a transient cycle (NEDC) on a dynamometric test bench. The benefits in terms of both fuel consumption and CO2 emissions reduction. The characterization of the backpressure associated with an eventual additional heat exchangers and the more complex layout of the oil circuit is assessed, as well as the transient effects produced by the faster oil warm-up and oil-coolant interaction on the engine thermal stabilization.
Exploitation assessment of geothermal energy from African Great Rift Valley
Authors: Bonechi N. , Fiaschi D. , Manfrida G. , Talluri L. , Zuffi C.
Published: October 2021

Countries that are in the Great Rift Valley have one of the lowest average annual electricity consumption per capita in Africa with a value of 164 kWh per inhabitant. Furthermore, the electrification rate is 34% that is more than fifty percentage points below the world average, which is around 86%.

One possible solution to improve the electrification rate is to properly exploit the energy resources present in the territory. One of the most significant energy sources of this region is certainly geothermal energy which has a potential of about 15 GWe, mostly concentrated in Ethiopia. Furthermore, it is possible to find the resource in a wide temperature range, not only to produce electricity, which, nonetheless, has a very limited exploitation rate, as only 900 MWe are installed between Kenya and Ethiopia, but also for direct use.

In this study, two geothermal power plants for two different geothermal sites, Corbetti and Arus-Bogoria, respectively in Ethiopia and Kenya, have been hypothesized after analyzing the resource potential. For the first, which has been estimated to be of high enthalpy (~300°C), a flash plant configuration was assumed, and the estimated energy production potential was found to be around 50-100 MWe. While for the second, at medium enthalpy (T<200°C), the use of a binary cycle plant was assumed with an obtained production of about 20 MW of electricity. Finally, the possibility of geothermal water exploitation for greenhouse heating, drying of agricultural products, civil sanitary uses, recreational uses (spa), or for industrial purposes has been assessed.
Performance Analysis of a Biodiesel-Fired Engine for Cogeneration
Authors: Falbo Luigi , Ramundo Ernesto
Published: October 2021

The continuous demand to reduce both the pollutant emissions and the greenhouse gas (GHG) is increasing the use of alternative fuels as biodiesel in direct-injection compression ignition engines under combined heat and power (CHP) configuration. Although the biodiesel has different thermophysical properties compared to the standard diesel, it can be used in compression ignition engines without significant modifications. However, the pure biodiesel and biodiesel/diesel blends provide different performance and combustion characteristics with respect to the standard diesel engine. In order to estimate the behaviour of a micro-CHP system fuelled with biodiesel, a zero dimensional (0D) numerical model was development. This model is based on a single zone model and predicts the behaviour of a biodiesel/diesel blend-fired engine at full and partial load in terms of electrical efficiency, thermal efficiency and specific fuel consumption. Notwithstanding the biodiesel/diesel blend reveals lower performance in terms of electric and thermal efficiencies, can be used in CHP systems preserving the environmental sustainability avoiding significant modifications in the engine architecture.
The potential of building integrated Photovoltaic (BIPV) systems for reducing the energetic impact of Italian supermarkets
Authors: Franco Alessandro , Cillari Giacomo , Fantozzi Fabio
Published: October 2021

In the perspective of sustainable cities, urbanist and planners have to deal with a constantly increasing penetration of renewable energy systems (RES) in the urban structure: in tertiary sector, retail and supermarket stores as particularly energy-intensive compounds play a core role in this scenario, as they are often characterized by similar kinds of structures mostly, large surfaces and a single floor, and analogous composition of energy loads. Most of the current research focuses on energy efficiency, but these buildings are particularly interesting for a systematic application of PhotoVoltaic (PV) generation technology as the energy uses associated with them are mainly electrical, in connection with air conditioning and food cooling. This article analyses the energy consumption in the supermarket sector for the sale of food. After an analysis of the main energy consumption parameters, standard solutions for the sizing of PV systems are proposed based on different design objectives, highlighting the potential of each proposed solution. Results show that a high percentage of self-consumption can be achieved, and that a battery storage set at a mean daily PV potential production level (4 kWh/kW in the case) perfectly suits to reach a self-sufficiency between 50-70%. Retail and food stores have proven to be a perfect promoter for PV diffusion either in a high self-consumption configuration, or turning them into energy hub for mobility to building or energy sharing policies.
The potential of CSP plants for remote communities in the MENA region
Authors: Ghirardi Elisa , Brumana Giovanni , Franchini Giuseppe
Published: October 2021

The present work aims to investigate the load-following capability of a tower-based CSP plant assumed to cover a high fraction (90%) of the power demand of a mid-size remote community. The design of a CRS requires the determination of several variables (number of heliostats, layout arrangement, tower height, receiver dimensions) depending on the solar field size and the site location. In this paper, a two-step optimization procedure is presented. A preliminary optimization is carried out to define the solar field configurations minimizing the budget costs for a range of receiver thermal design powers (from 300 MWth to 1000 MWth). The second optimization, based on annual simulation, selects the storage tank volume, the steam turbine rated power, and the actual reflective area (number of mirrors) capable to cover 90% of the power demand at minimum cost. The analysis is carried out for two load profile and two locations in Egypt. The load profile, compared to the solar radiation availability, determines the relationship between tank capacity and turbine size. The level of radiation has the strongest impact on the oversizing of the solar field and levelized cost of electricity.
Design, optimization, and testing of a high-speed centrifugal pump for motorsport application
Authors: Mariani Luigi , Di Giovine Giammarco , Di Battista Davide , Cipollone Roberto
Published: October 2021

Centrifugal pumps are designed to have their BEP (Best Efficiency Point) for a given flow rate, hydraulic head, and speed. In the design phase, those parameters are combined into a dimensionless specific speed used to define geometry of the pump.

In this paper, a downsized centrifugal pump has been designed to have high efficiency at very high speeds (10000 – 15000 RPM), as requested by the cooling circuit of an engine for motorsport and racing applications. The pump design point was 13 L/min and 3.0 bar at 12000 RPM, while the impeller external diameter is 34 mm.

A mathematical model has been realized to optimize the pump in the early design phase through an iterative process, based on a 0D procedure which generates the optimal geometry of both impeller and volute. Hence, the model estimates main losses and, thus, hydraulic, volumetric, and organic efficiency. Once the geometry is generated, the performance of the pump has been verified on the design working point through a detailed CFD analysis. Physical phenomena that occur when the pump is running have been simulated, to represent as closely as possible vein fluid detachments, cavitation, and backflow at clearances between impeller and pump casing.

At last, a prototype of the pump has been built and experimentally characterized in a dynamic test bench able to reproduce the characteristic curves (hydraulic head and efficiency) at very high revolution speeds as well as the performances in real time-varying operational conditions.
Measurement of GT exhaust gas temperature by acoustic pyrometry: Preliminary error investigation
Authors: Caposciutti Gianluca , Ferrari Lorenzo
Published: October 2021

Acoustic pyrometry is an interesting technique that may find several useful applications in turbomachinery. It is well known that the speed of sound in a medium is directly related to its temperature. Acoustic pyrometry estimates the temperature of a gas by considering the time of flight of an acoustic wave moving through it. If one acoustic emitter-receiver couple is used, only the average temperature along the acoustic path can be determined. If multiple emitter-receiver couples laying on the same plane are used, a reconstruction of the temperature map in the section is possible. In this last case, the analysis is based on the fact that the temperature of each sub portion of the section affects the time of flight of all the acoustic paths travelling across it. Many parameters affect the accuracy of the measurement. They are mainly related to the physic of the sound propagation in a medium, the accuracy of the instrumentation used, the interaction between the acoustic wave and the flow velocity and the hardware set-up. In this study, the impact of the measurement set up of an acoustic pyrometry for the measurement of the exhaust gas temperature in a gas turbine was investigated to determine the optimal solution in terms of accuracy and robustness to uncertainties.
Influences of high-reflective mulching membrane coupled with a drip sub-irrigation system on temperature and humidity of the soil
Authors: Di Giuseppe Alessia , Manni Mattia , Petrozzi Alessandro , Becchetti Laura Maria , Castellani Beatrice , Nicolini Andrea , Rossi Federico , Cotana Franco
Published: October 2021

The present study deals with an original application of RR materials to the agriculture sector, evaluating the effectiveness of a high-reflective mulching membrane treated with glass micro-spheres and coupled with a drip sub-irrigation system. An experimental facility, in which this technology is exploited, has been set up in Perugia (Italy). Influences of the mulching membrane on hygrothermal properties of the soil were evaluated through humidity and temperature sensors during the monitoring campaign. Data from unmulched field section was used as a reference case. The effectiveness of this technology was evaluated by focusing on three days that are representative of as much weather conditions. The monitoring campaign conducted from April to May 2021 has demonstrated that the high-reflective mulching membrane can reduce the temperature and relative humidity fluctuations throughout the day. In addition, the mulching membrane can reduce the soil temperature at different depths (i.e. 0.05 m, 0.10 m, and 0.15 m). The highest soil temperature reduction was found equal to 8.95°C at 0.15 m. Basing on such preliminary results, a more detailed and extended monitoring campaign will be performed in summer conditions.
Numerical calculation and experimental study on friction and lubrication of Stirling engine piston ring
Authors: Songjian Li , Wei Zheng , Wei Xu , Hong Ling
Published: October 2021

To solve the practical problem of Stirling engine piston ring, numerical model on friction and lubrication were established based on average Reynolds equation theory. Numerical calculation results show: piston rings are in the mixed lubrication state which gas lubrication film and micro-convex body contact existing simultaneously; contact pressure is 2 orders of magnitude less than gas film pressure; contact pressure is approximately linearly related to mean gas pressure. Simulated test rig was built and experimental results show: high-pressure working gas leak to intermediate chamber through piston rings, and the pressure of intermediate chamber drops sharply at lowest pressure of circulation; piston ring wear increases when rotational speed or working pressure increase. The accuracy of numerical model was proved by experimental phenomena and test data.