bluuebunny/crossref_metadata_2025 huggingface dataset:
Polygonal gold nanocrystal induced efficient phase transition in 2D-MoS2 for enhancing photo-electrocatalytic hydrogen generation
Authors: Das Santanu , Sharma Uttam , Mukherjee Bratindranath , Sasikala Devi Assa Aravindh , Velusamy Jayaramakrishnan
Published: December 2022

Plasmonic nanocrystals (NCs) assisted phase transition of two-dimensional molybdenum disulfide (2D-MoS2) unlashes numerous opportunities in the fields of energy harvesting via electrocatalysis and photoelectrocatalysis by enhancing electronic conductivity, increasing catalytic active sites, lowering Gibbs free energy for hydrogen adsorption and desorption, etc. Here, we report the synthesis of faceted gold pentagonal bi-pyramidal (Au-PBP) nanocrystals (NC) for efficient plasmon-induced phase transition (from 2 H to 1 T phase) in chemical vapor deposited 2D-MoS2. The as-developed Au-PBP NC with the increased number of corners and edges showed an enhanced multi-modal plasmonic effect under light irradiations. The overpotential of hydrogen evolution reaction (HER) was reduced by 61 mV, whereas the Tafel slope decreased by 23.7 mV/dec on photoexcitation of the Au-PBP@MoS2 hybrid catalyst. The enhanced performance can be attributed to the light-induced 2H to 1 T phase transition of 2D-MoS2, increased active sites, reduced Gibbs free energy, efficient charge separation, change in surface potential, and improved electrical conductivity of 2D-MoS2 film. From density functional theory (DFT) calculations, we obtain a significant change in the electronic properties of 2D-MoS2 (i.e. work function, surface chemical potential, and the density of states), which was primarily due to the plasmonic interactions and exchange-interactions between the Au-PBP nanocrystals and monolayer 2D-MoS2, thereby enhancing the phase transition and improving the surface properties. This work would lay out finding assorted routes to explore more complex nanocrystals-based multipolar plasmonic NC to escalate the HER activity of 2D-MoS2 and other 2D transition metal dichalcogenides.
Learning biophysics with open simulations
Authors: Kiemeneij Wilbert , de Putter Lesley , Koopman Maaike
Published: December 2022

Physics education in secondary schools can include biophysics topics as electives. An open simulation based on a simulation like Minecraft for learning the workings of the action potential in human cells was designed and tested for students in upper secondary physics education. In small design and test cycles both the simulation engine and the classroom materials were developed. The simulation shows realistic results that go beyond the accompanying textbook. The finished prototype of the engine and the materials were used to study student reasoning during their simulation of the action potential. Results show that students reason together about what they see in the simulation to come to theories on the action potential process, showing profound learning. The students did not master the more open inquiry final assignment.
Investigate the physics of instant noodles in a hot cup using Arduino temperature sensors
Authors: Prasitpong Singha , Phayphung Wissarut , Rakkapao Suttida
Published: December 2022

The study explores the physics of cooking instant noodles in a hot cup using low-cost Arduino sensors developed as a thermocouple and an infrared thermometer. By pouring room temperature water onto a bag of calcium oxide (CaO) contained in the outside cup of the noodles, the exothermic reaction of CaO generates. Its energy is released into the water of the outside cup. This cooks the noodles, which are put into an inside cup. The amount of heat transferred to the water is measured. Moreover, the change in the temperature of the hot cooked noodles with time is investigated using Newton’s law of cooling. The experiment using the Arduino temperature sensors encourages undergraduate students to learn thermodynamics concepts from the instant noodles in a hot cup, primarily found in groceries.
Next generation high resolution perovskite direct conversion detector: Monte Carlo design optimisation and virtual clinical trial
Authors: O’Connell J , Kundu S , Saidaminov M , Bazalova-Carter M
Published: December 2022

We implement virtual clinical integration of next-generation perovskite detectors into common x-ray imaging devices. This was achieved by performing Monte Carlo (MC) optimisation of the design and benchmarking of low cost, high spatial resolution, direct conversion perovskite crystal x-ray flat panel imagers for a next generation of breast-, MV-, and kV-cone beam CT detectors. Semiconductor methylammonium lead bromide perovskite crystals energy deposition efficiencies calculated in TOPAS were benchmarked against four common detector materials for twelve detector crystal thicknesses between 40 to 15 mm and ten beam energies ranging from 20 keV to 6 MeV. Based on these simulations, Koning's dedicated breast CT, and Varian's Truebeam kV- and MV-cone beam CT systems were designated as suitable applications for perovskite detectors. System specific Fastcat hybrid MC cone beam CT image simulation was subsequently used to optimise the perovskite detector design and conduct virtual clinical trials. Device-specific optimal perovskite crystal thicknesses were calculated to be 0.30, 0.86, and 1.99 mm for Koning breast CT and Truebeam kV- and MV-cone beam CT systems, respectively. Replacing the current detectors on these machines with low cost perovskite crystal detectors could be advantageous as it would simultaneously yield 12.1%, 9.5% and 86.1% improvements in detective quantum efficiency as well as increases in contrast to noise ratio in brain, lung, and bone tissues.
Mutual interferences between SIAT aPET insert and a 3 T uMR 790 MRI scanner
Authors: Sang Ziru , Kuang Zhonghua , Wang Xiaohui , Ren Ning , Wu San , Niu Ming , Cong Longhan , Liu Zheng , Hu Zhanli , Sun Tao , Liang Dong , Liu Xin , Zheng Hairong , Li Ye , Yang Yongfeng
Published: December 2022

Objective. Dual-modality small animal PET/MR imaging provides temporally correlated information on two biochemical processes of a living object. An magnetic resonance imaging (MRI)-compatible small animal PET insert named Shenzhen Institutes of Advanced Technology (SIAT) aPET was developed by using dual-ended readout depth encoding detectors to simultaneously achieve a uniform high spatial resolution and high sensitivity at the SIAT. In this work, the mutual interferences between SIAT aPET and the 3 T uMR 790 MRI scanner of United Imaging was quantitatively evaluated. Approach. To minimize the mutual interferences, only the PET detectors and the readout electronics were placed inside the MRI scanner, the major signal processing electronic was placed in the corner of the MRI room and the auxiliary unit was placed in the MRI technical room. A dedicated mouse radio fRequency (RF) coil with a transmitter and receiver was developed for the PET insert. The effects of PET scanner on the B
0 and B
1 field of the MRI scanner and the quality of the MRI images were measured. The effects of MRI imaging on the performance of both the PET detectors and scanner were also measured. Main results. The electronic and mechanical components of the PET insert affected the homogeneity of the B
0 field. The PET insert had no effect on the homogeneity of B
1 produced by the dedicated mouse coil but slightly reduced the strength of B
1. The mean and standard deviation of the RF noise map were increased by 2.2% and 11.6%, respectively, while the PET insert was placed in the MRI scanner and powered on. Eddy current was produced while the PET insert was placed in the MRI scanner, and it was further increased while the PET insert was powered on. Despite the above-mentioned interferences from the PET insert, the MR images of a uniform cylindrical water phantom showed that the changes in the signal-to-noise ratio (SNR) and homogeneity as the PET insert was placed in the MRI scanner were acceptable regardless of whether the PET insert was powered off or powered on. The maximum reduction of SNR was less than 11%, and the maximum reduction of homogeneity was less than 2.5% while the PET insert was placed inside the MRI scanner and powered on for five commonly used MRI sequences. MRI using gradient echo (GRE), spin echo (SE) and fast spin echo (FSE) sequences had negligible effects on the flood histograms and energy resolution of the PET detectors, as well as the spatial resolution and sensitivity of the PET scanner. Significance. The mutual interference between the SIAT aPET and the 3 T uMR 790 MRI scanner are acceptable. Simultaneous PET/MRI imaging of small animals can be performed with the two scanners.
Q-learning-based migration leading to spontaneous emergence of segregation
Authors: He Zhixue , Geng Yini , Du Chunpeng , Shi Lei , Wang Zhen
Published: December 2022

Understanding population segregation and aggregation is a critical topic in social science. However, the mechanisms behind segregation are not well understood, especially in the context of conflicting profits. Here, in the context of evolutionary game theory, we study segregation by extending the prisoner’s dilemma game to mobile populations. In the extended model, individuals’ types are distinguished by their strategies, which may change adaptively according to their associated payoffs. In addition, individuals’ migration decisions are determined by the Q-learning algorithm. On the one hand, we find that such a simple extension allows the formation of three different types of spontaneous segregation: (a) environmentally selective segregation; (b) exclusionary segregation; and (c) subgroup segregation. On the other hand, adaptive migration enhances network reciprocity and enables the dominance of cooperation in a dense population. The formation of these types of segregation and the enhanced network reciprocity are related to individuals’ peer preference and profit preference. Our findings shed light on the importance of adaptive migration in self-organization processes and contribute to the understanding of segregation formation processes in evolving populations.
DFT study of electronic, optical, and elastic properties of double perovskites Rb2YAgX6 (X = Br, I) compounds for opto-electronic device applications
Authors: Manzoor Mumtaz , Noor N A , Iqbal M Waqas , Rashid M , Ullah Hamid , Dahshan A
Published: December 2022

Density functional theory calculations have been used to investigate the electrical, optical, and elastic characteristics of double perovskites Rb2YAgX6 (X = Br, I) halides for exploring their opto-electronic applications. For optimizing the lattice constants and structure parameters, we have fitted the Murnaghan equation of state to the total energies computed for a wide range of lattice volumes. For the ground state lattice constants, the computed electronic band structure diagrams show indirect wide band gaps of 4.2 eV and 3.2 eV for Rb2YAgBr6 and Rb2YAgI6, respectively. Our results indicate that both of the studied halides absorb electromagnetic radiations beyond the visible region and are therefore appear potential candidates for optoelectronic applications in the ultraviolet rage of spectrum. The mechanical stability and ductility of the two halides are examined in terms of the elastic constants. Our results clearly demonstrate that the device application potential of these double perovskite halides is interesting owing to their high mechanical stability and hardness.
Diffuse x-ray and gamma-ray limits on boson stars that interact with nuclei
Authors: Acevedo Javier F. , Bhoonah Amit , Bramante Joseph
Published: December 2022

Light bosonic dark matter can form gravitationally bound states known as boson stars. In this work, we explore a new signature of these objects interacting with the interstellar medium (ISM). We show how small effective couplings between the bosonic dark matter and the nucleon lead to a potential that accelerates ISM baryons as they transit the boson star, making the ISM within radiate at a high rate and energy. The low ISM density, however, implies the majority of Galactic boson stars will be too faint to be observable through this effect. By contrast, the diffuse photon flux, in hard x-rays and soft gamma-rays, produced by boson stars interacting with the ionized ISM phases can be sizable. We compute this diffuse flux and compare it to existing observations from HEAO-1, INTEGRAL and COMPTEL to infer limits on the fraction of these objects. This novel method places constraints on boson star dark matter while avoiding back-action effects from ambient baryons on the boson star configuration, unlike terrestrial searches where it has been noted that back-action can screen light bosonic fields. In addition, this study could be extended to other couplings and structures formed from light dark matter. For dark matter masses (10-14, 10-8) eV and boson star masses (10-10, 10-1)M⊙, we find the constraints on the fraction can go down to f*≲ 10-9for dark matter in boson stars that is directly coupled to the Standard Model.
Control of resistive wall modes in the spherical tokamak
Authors: Xia Guoliang , Liu Yueqiang , Hender T.C. , McClements K.G. , Trier E. , Tholerus E.
Published: December 2022

In this work, the MARS-F/K codes (Liu et al 2000 Phys. Plasmas
7 3681; Liu et al 2008 Phys. Plasmas
15 112503) are utilized to model the passive and active control of the n= 1 (n is the toroidal mode number) resistive wall mode (RWM) in a spherical tokamak (aspect ratio A = 1.66). It is found that passive stabilization of the RWM gives a relatively small increase in normalized beta above the no-wall limit, relying on toroidal plasma flow and drift kinetic resonance damping from both thermal and energetic particles. Results of active control show that with the flux-to-voltage control scheme, which is the basic choice, a proportional controller alone does not yield complete stabilization of the mode. Adding a modest derivative action, and assuming an ideal situation without any noise in the closed-loop, the RWM can be fully stabilized with the axial plasma flow at 5% of the Alfvén speed. In the presence of sensor signal noise, success rates exceeding 90% are achieved, and generally increase with the proportional feedback gain. On the other hand, the required control coil voltage also increases with feedback gain and with the sensor signal noise.
Short time extremal response to step stimulus for a single cell E. coli
Authors: Chatterjee Sakuntala
Published: December 2022

After application of a step stimulus, in the form of a sudden change in attractant environment, the receptor activity and tumbling bias of an E. coli cell change sharply to reach their extremal values before they gradually relax to their post-stimulus adapted levels in the long time limit. We perform numerical simulations and exact calculations to investigate the short time response of the cell. For both activity and tumbling bias, we exactly derive the condition for extremal response and find good agreement with simulations. We also make experimentally verifiable prediction that there is an optimum size of the step stimulus at which the extremal response is reached in the shortest possible time.
Data Driven Disaggregation Method for Electricity Based Energy Consumption for Smart Homes
Authors: Hussain Asad , Cimaglia Jacopo , Romano Sabrina , Mancini Francesco , Re Valerio
Published: December 2022

Sustainable energy systems must be capable of ensuring sustainable development by providing affordable and reliable energy to consumers. Hence, knowledge and understanding of energy consumption in the residential sector are indispensable for energy preservation and energy efficiency which can only be possible with the help of consumer participation. New energy efficiency methods are developed due to the global adoption of smart meters that monitor and communicate residential energy consumption. Moreover, energy monitoring of each appliance is not feasible, as it is a costly solution. Therefore, energy consumption disaggregation is an answer for cost-cutting and energy saving. Contrary to the non-intrusive load monitoring (NILM) approaches, which are based on high-frequency power signals, we propose a data-driven algorithm that requires only a time-series energy meter dataset, a few appliances’ data, and energy consumption data from a consumer-based online questionnaire. Afterward, the proposed algorithm disaggregates whole house energy consumption into nine different energy consumption sectors such as lighting, kitchen, cooling, heating, etc. The energy consumption disaggregation algorithm is applied to datasets of 10 homes under experimentation. One of the homes provides us with the knowledge of 96.8% energy consumption, where only 28% knowledge is reported by monitoring plugs and 68% knowledge obtained by unmonitored means. Finally, the energy consumption obtained by the algorithm is compared with actual energy consumption, which shows the excellent functioning of the developed method.
Hygrothermal evaluation of sustainable insulating panels
Authors: Liuzzi Stefania , D’Alessandro Marialuisa , Martellotta Francesco , Rubino Chiara , Stefanizzi Pietro
Published: December 2022

Interest in sustainable building materials is recently growing up due to the environmental pollution and the consequent need to reduce energy consumption. The building sector alone is responsible of the major share of the total energy expenditure mainly due to the indoor heating and cooling. This huge amount of energy can be reduced by choosing efficient thermal insulators based on renewable and natural sources. Among the bio-based components the by-products derived from the wood industry or, alternatively, from the food industry residues can represents a serious challenge towards the revaluation of wastes. On the other side the use of paper pulp originated from recycled paper and cardboard can be considered a valid alternative to the traditional components currently present on market. Here an effort has been made to realize a sustainable insulting panel using different recycled components: paper pulp, coffee pods and sawdust powder. The aim of the paper is to evaluate the thermal performances of the recycled-waste based panels. The measurements of the dry-state thermal conductivity, the thermal diffusivity and the volumetric heat capacity were performed by a transient plane source device. Furthermore, a numerical simulation was carried out to perform the hygrothermal behaviour of the best mix for the final experimental insulation panel.
The Thermal Network Approach to Model Occupants’ Heat and CO2 Generation Interactions: A Case Study in an Office Building in Panama
Authors: González Jinela , Mora Dafni , Austin Miguel Chen
Published: December 2022

This investigation proposes a methodology to predict indoor air temperature and CO2 levels. For this, a two-occupant office inside a building in the Technological University of Panama is taken as a case study and modeled in Designbuilder simulation software validated via experimental data. Here, a mathematical model that considers internal heat gains by the occupants and CO2 emissions, including physical characteristics and activities developed, is constructed via the thermal network (RC) and system identification approaches. Three linear grey-box models are identified: a 4R2C for cooling system mode, a 3R2C for natural ventilation conditions, and a 1R1C for CO2 model. The results showed that the identified model is useful for estimating the indoor air temperature under both modes: “natural ventilation on” and “cooling system on,” in separated situations. Thus, it is determined that by incorporating the internal heat gain generated by the occupant in the model identification process, the data set is closer to real values than implementing a standard value as suggested by the literature. On the contrary, the CO2 model allowed an approximation between estimated and real data, but this prediction must be developed in a non-linear model for better results.
Decision-Making Approach based on Multi-objective Optimization to Achieve Net-Zero Energy Neighborhoods through Retrofit in a Tropical Climate
Authors: Chung-Camargo Katherine , Chacón Lorena , Austin Miguel Chen , Castaño Carmen
Published: December 2022

Among the main causes of environmental deterioration worldwide, buildings are among those responsible for a large percentage of energy-related CO2 emissions. Because of this, finding solutions to this problem is necessary. This research project involves building the energy model of a neighbourhood located in Panama, Herrera province. The main elements were classified and systematized using DesignBuilder and then implemented in an optimization analysis that seeks to approximate the NZED standard. The optimization’s main objectives were to maintain or improve thermal comfort, reducing energy consumption to the lowest possible. The best design options were those given by the method of essential design variables determined in the sensitivity analysis. It was possible to conclude that combining changes in occupant behavior with specific changes in the envelope leads to a more efficient reduction in electricity consumption. Because they lead to a significant reduction in consumption without involving the cost of the total modification of the envelope, with these modifications, a reduction in electricity consumption of 52,852 kWh/year was obtained at a renovation cost of B/.19,890.00 with a recovery period of seven years.
Comparison of different heating generator systems to reduce energy consumption in social housing in a Mediterranean climate.
Authors: Vallati A , Fiorini C V , Oclon P , Grignaffini S. , Di Matteo M
Published: December 2022

This study analyses the energy consumption of a social housing built in the 80’s. This building typology is deteriorating over time with increased energy consumption for air conditioning and indoor comfort that is well below the standard. This typology is also widely diffused in the city’s building stock, especially in its suburbs. Thus, the energy efficiency of public social housing represents a major concern for the Italian national scene, and its improvement represents an effort of critical importance. However, public funding is significantly reduced compared to the past and. In addition, it is often difficult to act on passive systems, such as installing thermal insulation, or replacing terminal units inside apartments. In these cases, as an energy retrofit, it may be appropriate to evaluate the possibility of preserving as much of the existing distribution and supply system as possible, while modifying the thermal energy generation system. In general, where the boiler is not obsolescent, the idea is to propose a hybrid generation system with the inclusion of a heat pump (HHP), which could be implemented with renewable energy equipment, properly installed in the building. The main goal of the present work was to evaluate through dynamic analysis different HVAC scenarios, to assess the optimal configuration of the system for residential use. The results show that a hybrid system can lower the primary energy consumption up to 28%, thus allowing the employment of renewable energies within the social housing building stock.
Detailed CFD transient heat transfer modelling in a brake friction system
Authors: Orlandi Francesco , Milani Massimo , Montorsi Luca
Published: December 2022

In a brake system the contact between the friction grooves of the discs and the steel elements leads to a consistent heat dissipation that is excised by the oil thermal vector in its flowing along the grooves channels. These are very complicated physical system were many variables may be taken in consideration, first of all the extensive integration of the different time scheduling actions that take place and that characterizes the translation of the interacting bodies and the correspondent deceleration, and also the heat dissipation derived from this contact. The simulations of similar physical system may result in too expensive computational efforts leading to very complicated simulations that need to take in account an extensive coupling between many physics, first of all the solid/liquid heat transfer and then the turbulence and the bi-phase models for the oil/air mixture that serves as thermal refrigerator vector in the braking system. Herein a simplified 3D model that focuses only on a discs / piston coupling is presented were the braking action is simulated in a simplified way modelling the velocity of rotation of the elements and the dissipated heat during the braking cycle. Focusing on the grooves channels the oil flows and thermal averaged flows are presented and detail contours are used to characterise a single brake event.
Economic-Comparative Study for Carbon Neutrality During Ships Docking and in Port Operations: A Path Towards Maritime Sector Decarbonization
Authors: Di Micco S. , Silvestri L. , Forcina A. , Jannelli E. , Minutillo M.
Published: December 2022

According to the International Energy Agency (IEA) reports, the maritime sector was responsible for around 2% of global energy-related Carbon Dioxide (CO2eq) emissions in 2020 (i.e., 714 Mton). Currently, Heavy Fuel Oil (HFO) is used for supplying main and auxiliary Internal Combustion Engines (ICEs) on board ships, therefore it is responsible for local and global pollution. As matter of fact, HFO is contaminated with several different compounds including aromatics, sulfur, and nitrogen, making emission upon combustion more polluting compared to other fuel oils. In order to reduce pollution in maritime sector, the International Convention for the Prevention of Pollution from Ships (MARPOL) has prohibited ships using of HFO in ports. In this purpose, new solutions involving cleaner fuels as well as new propulsion technologies are needed.

This paper is aimed to evaluate the environmental advantages that can be reached by replacing the HFO with low emission fuels and alternative power technologies. In particular, three cases have been investigated: i) ICEs fed by diesel, ii) Fuel Cell Systems fed by “Yellow” hydrogen, iii) Fuel Cell Systems fed by “Green” hydrogen. The analysis has been carried out by applying the Well-to-Waves (WTW) method for estimating and comparing the avoided CO2eq and NOx emissions. Moreover, the economic feasibility has been carried out by estimating the investment and operating costs.
Performance and Emissions Comparison between Biomethane and Natural Gas Fuel in Passenger Vehicles: results of the third testing campaign
Authors: Cignini Fabio , Genovese Antonino , Ortenzi Fernando , Valentini Stefano , Caprioli Alberto
Published: December 2022

This paper shows the results of the third (and last) campaign in the BiomethER project (EU-LIFE). It aimed to achieve two newest bio-methane production plants in the Emilia Romagna region (Italy). This manuscript reports the measurements of emission and performance for the vehicles tested, as widely described in the previous papers. So, three passenger cars are fuelled with conventional natural gas and bio-methane from a BiomethER plant. The emissions and performances on the chassis dynamometer for each vehicle have been measured. Inspecting the combustion chambers of the engines allows for evaluating their wear condition. This campaign confirms the results achieved in the previous two campaigns; there are no appreciable deviations for fuel consumption, greenhouse gas and other pollutant emissions between the two gases. The inspection reveals that biomethane reduces the carbon deposits in combustion chambers compared to natural gas in national infrastructure.
Accelerometer-based SOC estimation methodology for combustion control applied to Gasoline Compression Ignition
Authors: Silvagni G. , Ravaglioli V. , Ponti F. , Corti E. , Moro D. , Brusa A. , Cavina N.
Published: December 2022

The European Community’s recent decision to suspend the marketing of cars with conventional fossil-fueled internal combustion engines from 2035 requires new solutions, based on carbon-neutral technologies, that ensure equivalent performances in terms of reliability, trip autonomy, refueling times and end-of-life disposal of components compared to those of current gasoline or diesel cars. The use of bio-fuels and hydrogen, which can be obtained by renewable energy sources, coupled with high-efficiency combustion methodologies might allow to reach the carbon neutrality of transports (net-zero carbon dioxide emissions) even using the well-known internal combustion engine technology. Bearing this in mind, experiments were carried out on compression ignited engines running on gasoline (GCI) with a high thermal efficiency which, in the future, could be easily adapted to run on a bio-fuel. Despite the well-reported benefits of GCI engines in terms of efficiency and pollutant emissions, combustion instability hinders the diffusion of these engines for industrial applications. A possible solution to stabilize GCI combustion is the use of multiple injections strategies, typically composed by 2 early injected fuel jests followed by the main injection. The heat released by the combustion of the earlier fuel jets allows to reduce the ignition delay of the main injection, directly affecting both delivered torque and center of combustion. As a result, to properly manage GCI engines, a stable and reliable combustion of the pre-injections is mandatory. In this paper, an estimation methodology of the start of combustion (SOC) position, based on the analysis of the signal coming from an accelerometer sensor mounted on the engine block, is presented (the optimal sensor positioning is also discussed). A strong correlation between the SOC calculated from the accelerometer and that obtained from the analysis of the rate of heat release (RoHR) was identified. As a result, the estimated SOC could be used to feedback an adaptive closed-loop combustion control algorithm, suitable to improve the stability of the whole combustion process.
In-Cylinder Pressure Estimation in a Multi-Cylinder Engine by Combining the Instantaneous Crankshaft Speed Data and a 0D Thermodynamic Model. Numerical Validation
Authors: Catalani I , Bosi L , Baroni A , Romani L , Vichi G , Bellissima A , Asai G , Minamino R , Ferrara G
Published: December 2022

Modern engines require continuous and detailed monitoring in order to minimize variations in performance and emissions during their operation. To this aim, the engine thermodynamic cycle must be brought into focus, with special emphasis on the combustion process.

The in-cylinder pressure is the parameter that is most directly associated with the engine thermodynamic cycle. Direct measurements by means of dynamic pressure sensors are commonly used for research and development purpose. Currently, however, the cost and intrusiveness of such sensors, together with the harsh operating conditions that limits their lifetime, make direct measurements of the in-cylinder pressure not yet suitable for mass production applications. As a consequence, there’s great interest in developing cost-effective and reliable alternative solutions to extract pressure trace and combustion indicators such as the indicated mean effective pressure (IMEP).

The paper presents a technique for reconstructing the pressure cycle of each cylinder of a multi-cylinder engine by combining the instantaneous crankshaft speed information and a 0D thermodynamic model. Crankshaft position, angular velocity and angular acceleration, coupled with the engine inertia, are used to estimate the effective torque oscillation. The average indicated torque and the combustion torque contribution of each cylinder are then evaluated by coupling the information coming from engine speed and the 0D model. Eventually, through the kinematic relationship between the effective torque and the indicated pressure, the in-cylinder pressure trace is reconstructed.

The methodology proposed by the authors allows to evaluate the indicated pressure of each cylinder: this is especially useful for detecting cylinder-to-cylinder variations and misfiring events. Data from a 1D calibrated numerical model of a four-cylinder engine is used for preliminary validation at different engine speeds and loads.
Dynamic modelling of a dual-source heat pump system through a Simulink tool
Authors: Natale Christian , Naldi Claudia , Dongellini Matteo , Morini Gian Luca
Published: December 2022

In this paper, the performance of a reversible Dual-Source Heat Pump (DSHP) system, able to exploit renewable energy from, alternatively, air and ground sources, is evaluated by using Matlab-Simulink. The actual source exploited depends on a simple control strategy on the basis of the current external air temperature. Yearly dynamic simulations have been carried out by coupling the DSHP to a detached residential building located in Bologna, in which heating and cooling loads are strongly unbalanced, and coupled to a Borehole Heat Exchangers (BHEs) field. Different case studies have been analysed in which the length of the borefield has been modified. The obtained results show that an optimal switching temperature can be determined to maximise the Annual Performance Factor (APF) for a fixed BHE field length. Additionally, it has been demonstrated that DSHPs can be very useful in order to reduce the total required length of the borehole heat exchangers and, consequently, the associated costs, and to solve the problems linked to the ground temperature drift, which can be originated by the presence of an undersized borefield and/or by unbalanced building loads. As a consequence, DSHPs can be suggested for the retrofitting of traditional ground-coupled heat pump systems in presence of undersized BHEs.
Fault diagnosis in district heating networks
Authors: Bahlawan H , Gambarotta A , Losi E , Manservigi L , Morini M , Saletti C , Spina P R , Venturini M
Published: December 2022

District Heating Networks (DHNs), which dispatch thermal energy from a heat source to end-users by means of a heat carrier, are composed of pipes that can be affected by faults that endanger system reliability. Thus, reliable diagnostic approaches have to be employed to evaluate the health state of the DHN.

In the framework of the ENERGYNIUS research project, the authors of this paper developed a diagnostic approach aimed at detecting and identifying the most frequent faults that affect DHN pipes, i.e., water leakages, heat losses and pressure losses. The diagnostic approach detects and identifies pipe faults by coupling a DHN model with an optimization algorithm. As a result, the health indices of each pipe of the DHN, the fault position, its type and magnitude are provided. This study investigates the capability of the diagnostic approach by using two datasets, in which challenging faults were hypothetically implanted in the DHN of the campus of the University of Parma.

The diagnostic approach successfully detected and identified both faults, by also accurately assessing fault magnitude. In addition, the relative error with which each DHN variable is predicted is lower than 0.06 %.
How Power-to-Gas strategy could reduce national Natural Gas consumption over the energy crisis period
Authors: Pastore Lorenzo Mario , Mojtahed Ali , Santoli Livio de
Published: December 2022

Europe is facing an energy crisis caused by the dramatic rise in gas prices. This situation is damaging the European economy and urgent measures to reduce gas consumption are crucial in the short term. This paper aims to analyse the potential contribution of the Power-to-Gas strategy to reduce the Italian consumption of Natural Gas (NG) in the context of the current energy crisis. To do so, the Italian energy system has been modelled by means the EnergyPLAN software. The electrolysers’ installation in the Italian energy systems has been simulated in combination with different levels of additional RES installation. The hydrogen production and the NG abatement potential have been calculated in each simulated scenario. Furthermore, the Natural Gas Abatement Cost (NGAC) has been assessed. By installing 1.5 GW of electrolysers, along with an additional 25 GW of renewables, about 140 ktonH2/year can be produced only by exploiting the RES excess. The total NG reduction due to both the RES generation and the hydrogen injection is more than 60 TWh/year. The NG abatement cost varies between 45 and 54 €/MWh. At current gas prices, it is therefore extremely cheaper to invest in a drastic reduction of natural gas than to buy the same amount of gas on the wholesale market. Therefore, the current energy crisis can be an opportunity to accelerate the energy transition process. The proposed solutions allow a substantial reduction in gas consumption with the consequent reduction in emissions and the country’s energy dependency.
Assessment of closed cycles operating with supercritical CO2 as bottoming of small combustion turbines
Authors: Akramieh Elham , Giuffrida Antonio
Published: December 2022

This work investigates the performance of supercritical CO2 power cycles bottoming small combustion turbines. As a matter of fact, the maximum power output of the topping cycle is limited to 10 MW, since there is a great number of commercial combustion turbine units for which the conventional combined cycle architecture with a bottoming steam power plant is not convenient. In detail, the partial heating cycle is the layout chosen for this study according to the interesting trade-off between heat recovery and cycle efficiency, with a limited number of components. Considering the investigated range of power production, single-stage radial turbomachines are selected and their efficiency values are not fixed at first glance but result from actual size and running conditions, based on flow rates, enthalpy variations as well as rotational speeds. Focusing on a number of cases, interesting considerations about the size of the components of the supercritical CO2 power cycle are possible thanks to the theory of similitude.
Integrated ORC-SOEC system for green hydrogen production from incineration of solid fuels
Authors: Rosati G , Baiguini M , Di Marcoberardino G , Invernizzi C M , Iora P G
Published: December 2022

In the present paper, green hydrogen production from biomass and municipal solid waste is evaluated, targeting circular economy and green energy transition objectives pursued through waste-to-energy valorisation. In particular, the study consists in designing and modelling a hydrogen production system that integrates a solid oxide electrolyser (SOEC) and an organic Rankine cycle (ORC) powered by the combustion of biomass or municipal solid waste (MSW). The resulting efficiency, corresponding to 100.70 kg/h of hydrogen production in the optimal scenario, varies between 15.44% and 22.70% depending on operating conditions considered. Although on the one hand, this efficiency is far from the cold gas efficiency of an alternative gasification process, on the other, incineration shows a larger processing capacity and fewer restrictions in the waste categorization. Moreover, unlike traditional gasification treatments, the proposed concept can yield three outputs, namely pure hydrogen, electricity, and heat, allowing greater flexibility according to the end users’ requests and achieving a cogeneration efficiency greater than 80% in every operating mode. Furthermore, some fairly simple preliminary treatments, aiming to reduce biomass or MSW water content, can increase the green hydrogen production rate.
Techno-economic assessment of small-scale solar tower plants with modular billboard receivers and innovative power cycles
Authors: Morosini Ettore , Gentile Giancarlo , Binotti Marco , Manzolini Giampaolo
Published: December 2022

This work investigates performances and costs of various configurations of 5 MWel solar tower CSP plants, located in Sicily. The design of the plants aims at comparing two solar towers concepts (i.e., a single tower and modular towers), both adopting billboard receivers. A sensitivity on various heat transfer fluids (i.e., solar salt and sodium), storage fluids (solar salt and NaCl-MgCl2) and power block technologies (i.e., steam Rankine and sCO2 cycles) is also proposed. For each investigated plant configuration, tailored numerical models are presented to assess the performances of each plant subsystem (e.g., solar field, receiver, piping system, power cycle). The results show very competitive LCOE (between 160 and 180 $/MWhel), achievable with satisfactory capacity factors (around 55%), while suggesting good profitability levels for such investments in small scale CSP plants.
Understanding the near and post-stall behavior of wind turbine blade airfoils through multi-fidelity CFD simulations: the case of S809 airfoil
Authors: Innocenti G , Giaccherini S , Pinelli L , Bianchini A , Arnone A
Published: December 2022

For many years, wind turbine blade experts have based their designs on airfoil polars obtained with panel methods. These are quick to be set and sufficiently robust. On the other hand, their accuracy intrinsically decreases after stall, where simple post-stall extrapolation functions are introduced. Also, the complex shapes of wind turbine blade airfoils, especially the thick ones for use near the hub, introduce challenging simulation requirements at low Reynolds (Re) numbers. Both these issues are now coming at hand in many modern wind energy applications, like for example in stall-controlled small turbines or in utility-scale rotors experiencing extreme loading in parked conditions. Overall, it is acknowledged that higher-accuracy airfoil polars are needed to keep the reliability of engineering design methods high. The present study aims at numerically investigating the potential impact of high-fidelity, Computational Fluid Dynamics (CFD) techniques in predicting the near and post-stall behavior of a typical wind turbine blade airfoil in comparison to both state-of-the-art panel methods and RANS CFD approaches. To this end, the ubiquitous S809 test case has been selected, as it is known to be particularly challenging and for which experimental data have been available from the literature. More specifically, an extended analysis has been first carried out using a RANS approach (both steady and unsteady) to assess the sensitivity on the main simulation settings, with particular focus on turbulence closure. Then, a few high-fidelity simulations based on both the traditional DDES and the innovative LBM approaches have been performed to investigate the rate of improvement in modeling the underlying physics when the airfoil operates in the post-stall regime. Finally, a critical analysis of the different approaches is carried out and the prospects for wind energy applications are discussed.
Performance analysis of a bio-diesel fired engine bottoming with micro-ORC
Authors: Falbo Luigi , Bova Sergio
Published: December 2022

The purpose of this work is to investigate the performance in terms of electric power and electric efficiency of a 11kW bio-diesel internal combustion engine (ICE) coupled with a micro Organic Rankine Cycle (ORC) both in design and off-design conditions. A zero dimensional (0D) thermodynamical engine model has been developed to predict the electric and thermal power with 100% biodiesel fuel (B100). B100 has been selected for the performance analysis of the integrated system due its lower environmental impact. For the ORC system, a subcritical thermodynamic model has been used with various working fluid (R245fa, R1233zd(E), R134a, R1234ze(E) and R1234ze(Z)). A plate heat exchanger (PHEX) has been adopted as evaporator of the organic cycle to directly recover the thermal power of the exhaust gas. Both models have been validated using experimental data from literature. Two different expander configurations, dynamic and volumetric, has been investigated. Model validations show good agreement with the experimental and literature data, respectively. Moreover, the results highlight that the micro-ORC could achieve a maximum electric efficiency of about 7% at full load with R1234ze(Z). Although at part load the dynamic expander show better performance, the volumetric expander has been selected for the system analysis due to its real suitability for small and micro scale ORC. Combined system results show a maximum enhancement of engine efficiency of about 5%, and better results, in terms of good compromise between electric efficiency and operating range width, has been shown for R1233zd(E). Furthermore, the direct coupling of the PHEX with the exhaust gases allows to have heat exchange evaporator areas below 2 m2 for all analysed fluids.
Liquid film formation: prediction accuracy of different numerical approaches
Authors: Agati Giuliano , Evangelisti Adriano , Gabriele Serena , Rispoli Franco , Venturini Paolo , Borello Domenico
Published: December 2022

In counteracting fouling phenomenon in gas turbines, which leads to system inefficiencies and performance degradation, water washing technique is very often adopted. Water droplets sprays are injected and, hitting the solid surfaces, remove the dirt deposition. Among the collateral undesirable phenomena related to water washing, blades erosion and liquid film formation are the most remarkable. Despite the former issue was extensively assessed by the authors in previous works, up to the authors’ knowledge the risk of liquid film formation due to water washing was scarcely investigated. Liquid film formation and spreading on a solid surface is a complex phenomenon involving a large number of physical events, such as: droplets impact on a solid surface, splashing phenomena, liquid film dragging under the effect of the carrier phase and droplets separation from the film in proximity of geometry discontinuities. In this paper, an extensively used experimental test case involving all these phenomena was used to test different numerical wall film models available in literature. The test case consists in the injection of a liquid jet in a high velocity crossflow. Some of the liquid jet mass impacts on the opposite solid surface generating a wall film which develops under the dragging effect of the crossflow. A Lagrangian approach was used to track the suspended droplets within the flow field by also considering the turbulent dispersion by means of a Random Walk model. Droplets-wall interaction is considered according to the Stanton-Rutland model, which provides the outcome of a collision (deposit, rebound or splashing), depending on the local impact conditions. If a droplet sticks on a solid boundary, a liquid film generates. Droplets atomization is also accounted for by using the Madabhushi model while Friederich separation model was selected to take into account the detachment of droplets from the film at the geometry edge. Three different numerical simulations have been performed based on different approaches used to solve the liquid film evolution, namely Eulerian one-way coupling, Eulerian two-way coupling and Lagrangian two-way coupling. Numerical results have been compared with the experimental ones from both a qualitative and a quantitative point of view. The wall film shape, its spatial distribution and the variation of the film thickness of the wall centreline have been compared between experimental and numerical simulations proving that the Lagrangian 2-way coupling approach better reproduces the liquid film dynamics observed in the experiments.
Implementation of Lora for Controlling and Monitoring Broiler Cage Temperature
Authors: Madona E. , Yulastri  , Nasution A. , Prayogi
Published: December 2022

A system for controlling the temperature of broilers cages has been made with LoRa data communication. The purpose of this research is to make a prototype of a control system for monitoring and controlling the temperature of broiler controlled by a microcontroller with LoRa communication. The results of measuring system performance are indicated by the DHT11 sensor reading error occurs when the temperature is 36,37 °C and 38 °C by 1.03%. The device that can connect to LoRa is 320 m in Line of Sight (LOS) conditions and 52 m in Non Line of Sight (NLOS) conditions. Overall the tool can function well. Suggestions for further research, an Internet of Things (IoT) based monitoring system can be added using a mobile application.