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Ancona, M. A., M. Bianchi, L. Branchini, A. De Pascale, F. Melino, S. Ottaviano, A. Peretto et C. Poletto. « Experimental and numerical investigation of a micro-ORC system for heat recovery from data centers ». Journal of Physics : Conference Series 2385, no 1 (1 décembre 2022) : 012122. http://dx.doi.org/10.1088/1742-6596/2385/1/012122.
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Abstract In the effort to enhance the recovery of waste energy, data centers are drawing attention because of the huge amount of heat discharged from the computer racks. Organic Rankine cycle (ORC) power systems are a viable solution to exploit servers’ waste heat, as it is available at very low temperatures. The purpose of this study is to assess the feasibility of integrating a micro-ORC system into data centers cooling systems and its potential energy saving. An experimental analysis is carried out on a kW-scale ORC test bench, with R134a as working fluid. Heat is supplied at temperatures and flow rates in the range respectively 40-55 °C and 1.8-5 m3/h, consistently with typical values observed in data centers application, showing the second law efficiency varying between 5% and 13%. Furthermore, a steady-state model of the micro-ORC has been recalibrated and validated against experimental data; the built-in volume ratio of the reciprocating piston expander has been optimized to improve the filling performance of the machine. A parametric analysis, varying the boundary conditions within their range of interest for this application, and the working fluid (R1234yf and R1234ze(E)), shows that a maximum second law efficiency of 30% is achievable with R1234ze(E).
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Peris, Bernardo, Joaquín Navarro-Esbrí, Francisco Molés, Jose Pascual Martí et Adrián Mota-Babiloni. « Experimental characterization of an Organic Rankine Cycle (ORC) for micro-scale CHP applications ». Applied Thermal Engineering 79 (mars 2015) : 1–8. http://dx.doi.org/10.1016/j.applthermaleng.2015.01.020.
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Casari, Nicola, Ettore Fadiga, Michele Pinelli, Saverio Randi et Alessio Suman. « Pressure Pulsation and Cavitation Phenomena in a Micro-ORC System ». Energies 12, no 11 (8 juin 2019) : 2186. http://dx.doi.org/10.3390/en12112186.
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Micro-ORC systems are usually equipped with positive displacement machines such as expanders and pumps. The pumping system has to guarantee the mass flow rate and allows a pressure rise from the condensation to the evaporation pressure values. In addition, the pumping system supplies the organic fluid, characterized by pressure and temperature very close to the saturation. In this work, a CFD approach is developed to analyze from a novel point of view the behavior of the pumping system of a regenerative lab-scale micro-ORC system. In fact, starting from the liquid receiver, the entire flow path, up to the inlet section of the evaporator, has been numerically simulated (including the Coriolis flow meter installed between the receiver and the gear pump). A fluid dynamic analysis has been carried out by means of a transient simulation with a mesh morphing strategy in order to analyze the transient phenomena and the effects of pump operation. The analysis has shown how the accuracy of the mass flow rate measurement could be affected by the pump operation being installed in the same circuit branch. In addition, the results have shown how the cavitation phenomenon affects the pump and the ORC system operation compared to control system actions.
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Falbo, Luigi, et Sergio Bova. « Performance analysis of a bio-diesel fired engine bottoming with micro-ORC ». Journal of Physics : Conference Series 2385, no 1 (1 décembre 2022) : 012116. http://dx.doi.org/10.1088/1742-6596/2385/1/012116.
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Abstract 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.
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Moradi, Ramin, Emanuele Habib, Enrico Bocci et Luca Cioccolanti. « Component-Oriented Modeling of a Micro-Scale Organic Rankine Cycle System for Waste Heat Recovery Applications ». Applied Sciences 11, no 5 (24 février 2021) : 1984. http://dx.doi.org/10.3390/app11051984.
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Organic Rankine cycle (ORC) systems are some of the most suitable technologies to produce electricity from low-temperature waste heat. In this study, a non-regenerative, micro-scale ORC system was tested in off-design conditions using R134a as the working fluid. The experimental data were then used to tune the semi-empirical models of the main components of the system. Eventually, the models were used in a component-oriented system solver to map the system electric performance at varying operating conditions. The analysis highlighted the non-negligible impact of the plunger pump on the system performance Indeed, the experimental results showed that the low pump efficiency in the investigated operating range can lead to negative net electric power in some working conditions. For most data points, the expander and the pump isentropic efficiencies are found in the approximate ranges of 35% to 55% and 17% to 34%, respectively. Furthermore, the maximum net electric power was about 200 W with a net electric efficiency of about 1.2%, thus also stressing the importance of a proper selection of the pump for waste heat recovery applications.
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Jradi, Muhyiddine, et Saffa Riffat. « Performance Analysis of an Innovative ORC-based Micro-scale CCHP System under Lebanese Conditions ». International Journal of Thermodynamics 22, no 2 (23 mai 2019) : 98–105. http://dx.doi.org/10.5541/ijot.494481.
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Jradi, Muhyiddine, Jinxing Li, Hao Liu et Saffa Riffat. « Micro-scale ORC-based combined heat and power system using a novel scroll expander ». International Journal of Low-Carbon Technologies 9, no 2 (20 février 2014) : 91–99. http://dx.doi.org/10.1093/ijlct/ctu012.
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Liu, Hao, Yingjuan Shao et Jinxing Li. « A biomass-fired micro-scale CHP system with organic Rankine cycle (ORC) – Thermodynamic modelling studies ». Biomass and Bioenergy 35, no 9 (octobre 2011) : 3985–94. http://dx.doi.org/10.1016/j.biombioe.2011.06.025.
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Kicinski, J., et G. Zywica. « Prototype of the domestic CHP ORC energy system ». Bulletin of the Polish Academy of Sciences Technical Sciences 64, no 2 (1 juin 2016) : 417–24. http://dx.doi.org/10.1515/bpasts-2016-0047.
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Abstract The Institute of Fluid-Flow Machinery (IMP PAN) in Gdansk pursues its own research in fields such as technologies that use renewable energy sources efficiently, including in particular the small-scale combined heat and power (CHP) systems. This article discusses the design concepts for the prototype of small CHP ORC (organic Rankine cycle) energy system, developed under the research project. The source of heat is a boiler designed for biomass combustion. Electricity was generated using specially designed oil-free vapour micro-turbine. The turbo-generator has compact structure and hermetical casing thanks to the use of gas bearings lubricated by working medium. All energy system components are controlled and continuously monitored by a coherent automation and control system. The article also discusses selected experimental results conducted under laboratory conditions. Thermal-flow tests were presented that allow for an assessment of the operation of energy system components. Additionally, energy performance results of the turbo-generator were given including power obtained at various cycle parameters. The achieved results have shown that the developed energy system operated in accordance with design solutions. Electricity derived from the energy system prototype was around 2 kW, with boiler’s thermal power of 25 kW. The research has also confirmed that this system can be used in a domestic environment.
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Spale, Jan, Guk Chol Jun, Vaclav Novotny, Philipp Streit, Andreas P. Weiß et Michal Kolovratnik. « Development of a 10 kW class axial impulse single stage turboexpander for a micro-CHP ORC unit ». EPJ Web of Conferences 264 (2022) : 01044. http://dx.doi.org/10.1051/epjconf/202226401044.
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Development of micro ORC systems with 1-15 kW power output for micro-cogeneration and waste heat recovery at the Czech Technical University in Prague, University Centre for Energy Efficient Buildings (CTU UCEEB) has over ten years of history with many successes. These include 6 different ORC units, all with in-house designed rotary vane expanders (RVE) of many versions throughout this development. Among main advantages of the RVE belong relatively simple and robust design at low cost even at very small series of single-unit production and all that with acceptable efficiency. The ORC units operate with hexamethyldisiloxane (MM) working fluid at high pressure ratios and expansion ratios and the isentropic efficiency of RVE has a limit at these conditions around 60%, often however only at values around 50%. While this might be enough on a cost side for commercialization of this technology, in pursuit of higher efficiency solutions, different expander technology needs to be selected. A turbo-expander is a logical choice with prospect of higher efficiency. At the same time, a literature review has found a lack of reported detailed experimental data for micro (5-50 kW) turbo-expanders, possibly hindering global development towards economically feasible solutions. A project named Dexpand, “Optimised expanders for small-scale distributed energy systems” aims at these issues by objectives in designing, optimizing, manufacturing and testing several ORC expanders with MM and isobutane and their subsequent performance mapping and comparison. One major task is a design of a turboexpander for a 120 kWth biomass fired microcogeneration ORC unit currently operated at the CTU UCEEB. An axial impulse single stage turboexpander was selected as a suitable choice, providing a prospect of a decent efficiency at technically manageable rotational speed and size. This paper provides a detail of currently performed design activities, starting from boundary conditions specification, over development and optimization of a 1D model, preliminary 2D CFD calculations and finishing in a state of a robust and detailed 3D CFD model with a real gas model. Note that the working fluid, high molar mass organic vapour, is highly non-ideal in its behaviour and the flow conditions with pressure design ratio around 13 is highly supersonic (nozzle outlet isentropic Mach number exceeds 2). The current results based on 3D CFD indicate a prospect of an isentropic efficiency 71% at mechanical power output of 11 kW. Lastly, ongoing and future work is outlined, which includes aerodynamic optimization based on the developed 3D CFD model and construction design of the entire turbine assembly.
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Suankramdee, Worakit, Tongchana Thongtip et Satha Aphornratana. « Development of a sliding vane expander in a micro-scale ORC system for utilizing low-grade heat ». Energy Procedia 138 (octobre 2017) : 817–22. http://dx.doi.org/10.1016/j.egypro.2017.10.078.
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Weiß, A. P., T. Popp, G. Zinn, M. Preißinger et D. Brüggemann. « A micro-turbine-generator-construction-kit (MTG-c-kit) for small-scale waste heat recovery ORC-Plants ». Energy 181 (août 2019) : 51–55. http://dx.doi.org/10.1016/j.energy.2019.05.135.
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Fatigati, F., M. Di Bartolomeo, D. Vittorini, A. Coletta, R. Carapellucci et R. Cipollone. « Small-scale ORC-based unit for domestic micro-cogeneration operating in the temperature range of the solar thermal flat panels ». Journal of Physics : Conference Series 2385, no 1 (1 décembre 2022) : 012114. http://dx.doi.org/10.1088/1742-6596/2385/1/012114.
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Abstract CO2 emissions related to the energy demand in commercial and residential buildings account for over 15% of worldwide greenhouse gases emissions. This issue requires the development of new solutions, technologies, and energy management strategies to reduce the environmental impact of this sector. Simultaneous heat and power production, namely cogeneration, is a proven method for this purpose. Among the different power systems, Organic Rankine Cycle (ORC) plants allow the production of mechanical and electric energy using hot sources at low temperature levels. This feature allows to combine this technology with solar collectors, making it possible to exploit the thermal energy exceeding the thermal needs when the solar irradiation is high. In this paper, an experimental characterization of a Solar Organic Rankine Cycle (SORC) is presented. The hot source of the power plant is reproduced by water heated up to 120 °C by two 12 kW electric resistances and stored in a buffer tank with a capacity of 200 L. The 1 kW ORC unit is equipped with a scroll volumetric expander operating off-grid. The main control variable of the unit is the pump speed which is varied in each operating condition to guarantee a superheating degree at the expander inlet. Since the variability of the solar source is a critical issue in these applications, off-design operating conditions have been tested, showing the capability of the plant to be also operated far from the design point. The maximum efficiency of the unit reached 4.7 % while the highest net power was 400 W. A further test conducted to evaluate the transient performances of the unit demonstrated its small inertia and the capability of the expander to produce power right after the unit activation.
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Algieri, Angelo. « Comparative Investigation of the Performances of Subcritical and Transcritical Biomass-Fired ORC Systems for Micro-scale CHP Applications ». Procedia Computer Science 83 (2016) : 855–62. http://dx.doi.org/10.1016/j.procs.2016.04.176.
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Mascuch, Jakub, Vaclav Novotny, Vaclav Vodicka, Jan Spale et Zbynek Zeleny. « Experimental development of a kilowatt-scale biomass fired micro – CHP unit based on ORC with rotary vane expander ». Renewable Energy 147 (mars 2020) : 2882–95. http://dx.doi.org/10.1016/j.renene.2018.08.113.
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Suankramdee, Worakit, Tongchana Thongtip et Satha Aphornratana. « Experimental study of a sliding vane expander in a micro-scale ORC system for utilizing low-grade heat ». Energy Procedia 138 (octobre 2017) : 823–28. http://dx.doi.org/10.1016/j.egypro.2017.10.085.
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Giovanni, Giardiello, de Nola Francesco, Ghezzi Giuliana, Gimelli Alfredo, Iossa Raffaele, Langella Giuseppe et Sessa Bernardo. « Model and transient Control strategy design of an Organic Rankine Cycle Plant for waste heat recovery of an Internal Combustion Engine ». Journal of Physics : Conference Series 2385, no 1 (1 décembre 2022) : 012118. http://dx.doi.org/10.1088/1742-6596/2385/1/012118.
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Abstract The multi-sources hybrid polygeneration energy systems are of great interest and topicality as they are one of the most promising technologies in the European’s Green Deal panorama, with the aim of serving users with electrical and thermal energy using a single plant powered by one or more energy sources. In the waste heat recovery field Organic Rankine Cycle (ORC) power plants are becoming increasingly popular, especially for exploiting medium and low temperature heat sources as a micro-small scale power plant. However, the development and diffusion of this technology is still limited due to the high costs and consequently prototype development and experimental assessment of performance is very poor, especially for non-stationary systems. In this work the modelling and validation of a micro-scale waste heat recovery (WHR) plant coupled with a control system is presented. An ORC plant has been modelled through a map-based model approach for the piston pump and the scroll expander while the pipes and the heat exchangers through a 1D thermo-fluid dynamic approach. A preliminary comparison was made between some numerical quantities of the modelled plant and the same experimental quantities in 61 different operating conditions, showing an average error of 50.1%. The model has been calibrated using a vector optimization technique: two calibration parameters of the heat exchangers were calibrated with a genetic algorithm (MOGA II) by reducing the error of 5 quantities obtained from the model with the respective experimental quantities in 15 different operating conditions. The remaining 46 operating conditions were used to evaluate the calibrated model, showing an average error of 3%. Furthermore, in order to provide for the use of the system coupled to highly variable heat sources, such as the exhaust gases of an internal combustion engine, a control strategy has been designed to perform two tasks: leading the ORC performance where the efficiency is higher, acting on the pump speed through a map-based control, implemented by a look-up table control, and protecting the organic fluid from damage caused by high working temperatures through a bypass control system with a PI control, depending on the proportional and integral gains. In order to verify the control strategy behaviour at different thermal transient inputs, a set of simulations has been run, showing a robust and stable manner preserving the organic fluid properties and limiting the superheated steam at expander inlet.
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Cappiello, Alessandro, et Raffaele Tuccillo. « Design and CFD Analysis of a Radial-Inflow Turbine for Small Scale ORC Applications ». E3S Web of Conferences 197 (2020) : 11005. http://dx.doi.org/10.1051/e3sconf/202019711005.
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In recent years, Organic Rankine Cycle (ORC) technology has received growing interests, thanks to its high flexibility and to the capability to exploit energy sources at temperature levels difficult to be approached with conventional power cycles. These features allow exploiting renewable and renewable-equivalent energy sources, by either improving the energy conversion efficiency of existing plants or using waste heat from industrial process. As far as the expander is concerned, a high potential solution is represented by turbo-expanders, which allow reduction of plant clutter and complexity, so enhancing the potential impact on the diffusion of small power ORC-based plants. The present work concerns the design of a RadialInflow Turbine for a bottoming Organic Rankine Cycle in the tens of kW scale. Design boundary conditions are retrieved by a zero-dimensional model of a solar-assisted micro gas turbine in cogenerating mode. The design process is started by means of an in-house mean-line design code accounting for real gas properties. The code is used to carry out parametric analyses to investigate the design space for several working fluids encompassing different classes, namely refrigerants and siloxanes. The program is used to assess the effect of design variables and working fluid on the turbine performance and turbine design characteristics. Subsequently, the most promising design candidates are selected and three-dimensional first guess stator and rotor geometries are built on these preliminary designs. Stationary and rotating passages are then meshed and analyzed by means of RANS CFD based solution of the stator – rotor interaction.
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Pereira, João S., João Almeida, Jorge C. André, Ricardo Mendes et José B. Ribeiro. « Modelling and experimental validation of the heat-transfer processes of a direct vaporization micro-scale ORC-evaporator for thermal degradation risk assessment ». Energy Conversion and Management 238 (juin 2021) : 114130. http://dx.doi.org/10.1016/j.enconman.2021.114130.
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Cioccolanti, Luca, Simone De Grandis, Roberto Tascioni, Matteo Pirro et Alessandro Freddi. « Development of a Fuzzy Logic Controller for Small-Scale Solar Organic Rankine Cycle Cogeneration Plants ». Applied Sciences 11, no 12 (13 juin 2021) : 5491. http://dx.doi.org/10.3390/app11125491.
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Solar energy is widely recognized as one of the most attractive renewable energy sources to support the transition toward a decarbonized society. Use of low- and medium-temperature concentrated solar technologies makes decentralized power production of combined heating and power (CHP) an alternative to conventional energy conversion systems. However, because of the changes in solar radiation and the inertia of the different subsystems, the operation control of concentrated solar power (CSP) plants is fundamental to increasing their overall conversion efficiency and improving reliability. Therefore, in this study, the operation control of a micro-scale CHP plant consisting of a linear Fresnel reflector solar field, an organic Rankine cycle unit, and a phase change material thermal energy storage tank, as designed and built under the EU-funded Innova Microsolar project by a consortium of universities and companies, is investigated. In particular, a fuzzy logic control is developed in MATLAB/Simulink by the authors in order to (i) initially recognize the type of user according to the related energy consumption profile by means of a neural network and (ii) optimize the thermal-load-following approach by introducing a set of fuzzy rules to switch among the different operation modes. Annual simulations are performed by combining the plant with different thermal load profiles. In general, the analysis shows that that the proposed fuzzy logic control increases the contribution of the TES unit in supplying the ORC unit, while reducing the number of switches between the different OMs. Furthermore, when connected with a residential user load profile, the overall electrical and thermal energy production of the plant increases. Hence, the developed control logic proves to have good potential in increasing the energy efficiency of low- and medium-temperature concentrated solar ORC systems when integrated into the built environment.
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Algieri, Angelo, et Pietropaolo Morrone. « Energetic analysis of biomass-fired ORC systems for micro-scale combined heat and power (CHP) generation. A possible application to the Italian residential sector ». Applied Thermal Engineering 71, no 2 (octobre 2014) : 751–59. http://dx.doi.org/10.1016/j.applthermaleng.2013.11.024.
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Vittorini, Diego, Fabio Fatigati, Davide Di Battista, Marco Di Bartolomeo et Roberto Carapellucci. « Experimental Assessment of a Multi-Variable Control Strategy of a Micro-Cogeneration Solar-ORC Plant for Domestic Application ». E3S Web of Conferences 312 (2021) : 08006. http://dx.doi.org/10.1051/e3sconf/202131208006.
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Suitability to off-design operation, applicability to combined thermal and electrical generation in a wide range of low temperatures and pressures and compliance with safety and environmental limitations qualify small-scale Organic Rankine Cycle plants as a viable option for combined heat and power generation in the residential sector. As the plants scale down, the electric and thermal output maximization has to account for issues, spanning from high pump power absorption, compared to the electric output of the plant, to intrinsically low plant permeability induced by the expander, to the intermittent availability of thermal power, affected by the heat demand for domestic hot water (DHW) production. The present paper accounts for a flat-plate solar thermal collector array, bottomed by an ORC unit featuring a sliding vane expander and pump and flat-plate heat exchangers. A high-temperature buffer vessel stores artificially heated water – electric heaters, simulating the solar collector - and feeds either the hot water line for domestic use or the ORC evaporator, depending on the instantaneous demand (i.e., domestic hot water or electric power), the temperature conditions inside the tank and the stored mass availability. A low-temperature receiver acts like the heat sink of the ORC unit and harvests the residual thermal power, downstream the expander: a dedicated control, modelled to properly modulate the mass addition/subtraction to this storage unit allows to restore the operating points of the cycle and to limit the incidence of off-design operation, via real-time adjustment of the cycle operating parameters. Indeed, the possibility of continuous ORC generation depends on (i) the nature of the demand and (ii) the amount of hot water withdrawn from the high-temperature buffer vessel. The time-to-temperature for the mass stored inside the buffer affects the amount of ORC unit activations and eventually the maximum attainable generation of electric energy. The plant energy performance is experimentally assessed, and various characteristic operating points are mapped, based on test runs carried out on a real-scale ORC pilot unit.
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Streit, Philipp, et Andreas P. Weiß. « Parameterized, numerical design of a two-wheel Curtis steam turbine for small scale WHR ». MATEC Web of Conferences 345 (2021) : 00031. http://dx.doi.org/10.1051/matecconf/202134500031.
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In contrast to the current trend of converting waste heat into electricity in the small power range below 100 kWel by means of an ORC plant, the authors are pursuing the concept of a micro steam power plant equipped with a micro turbine. Water avoids many of the problems often associated with organic working fluids, such as flammability, toxicity, greenhouse gas effect and high fluid costs. However, water vapor makes turbine design more challenging. The physical reasons for this are repeated, and thereby it becomes clear why a velocity compounded two wheel Curtis turbine has been chosen. The used in-house 1D turbine design tool is briefly introduced. More focus is put on the shortcomings of the implemented 1D loss model and their negative impact on the current turbine design. Consequently, the authors continued actual turbine design by a parameterized approach in 3D CAD/CFD. This approach is explained, and finally, the CFD flow field and the performance maps of the designed turbine are discussed. The turbine is currently under construction and will be installed in 2022 in a waste heat recovery (WHR) plant in Nuremberg/Germany.
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Ding, X., L. C. Lee, David Lee Butler et Kah Chuan Shaw. « Effects of Crystallographic Structure on Machining Performance with Polycrystalline Oxygen Free Copper by a Single Crystalline Diamond Micro-Tool ». Key Engineering Materials 447-448 (septembre 2010) : 31–35. http://dx.doi.org/10.4028/www.scientific.net/kem.447-448.31.
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A study was carried out to investigate effects of crystallographic structure on the machining performance with polycrystalline oxygen free copper (OFC) using a single crystalline diamond (SCD) micro-tool. The SCD micro-tool used in this study fabricated with a focused ion beam (FIB) has a cutting length of around 30 µm on the primary clearance face. It was found that a change in crystallographic orientation resulted in a variation in machining force, chip thickness and shear angle, leading to a change in machined surface integrity. When a micro-size tool traverses within a grain at a machining direction aligned with a particular crystallographic orientation, the work material in front of the machining tool is found to be severely deformed. If the orientation changes to a less favorable orientation, this may lead to a much reduced shear angle, a thicker chip, striation at the chip back, higher machining forces and a degraded machined surface. This study contributes to the understanding of the physics of micro scale mechanical machining (micro-machining).
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Lungu, Magdalena Valentina. « Synthesis and Processing Techniques of Tungsten Copper Composite Powders for Electrical Contact Materials A Review ». Oriental Journal of Chemistry 35, no 2 (18 avril 2019) : 491–515. http://dx.doi.org/10.13005/ojc/350201.
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This review presents a general survey on synthesis and processing techniques of tungsten copper (W-Cu) composite powders for achieving electrical contact materials for power engineering applications. Several chemical and mechano-chemical synthesis methods for obtaining W-Cu composite powders in nano or micro scales from various W and Cu metal salt precursors combined with hydrogen reduction or nitridation-denitridation processes are reported along with powder metallurgy (PM) techniques employed in manufacturing W-Cu electrical contact materials. The main advantages and disadvantages of synthesis and processing techniques are summarized, too. The interdepencies among the properties of starting materials and final products in relation with synthesis and processing parameters are highlighted. The review reveals that the development of W-Cu advanced materials with improved properties and scale-up potential is of a great interest in practical applications related to materials science and engineering field.
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Morawska, Sylwia, et Przemysław Banasik. « Responsible court in the global world – managerism or managerialism ». Oeconomia Copernicana 6, no 4 (31 décembre 2015) : 29. http://dx.doi.org/10.12775/oec.2015.027.
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One can look at the improvement of the effectiveness and efficiency of the justice system from three perspectives: macro, mezo, and micro. After all, the general goal is to enhance the effectiveness and efficiency of the justice system as a whole (the macro perspective), the courts (the mezo scale), and court proceedings (the micro scale). The need to improve the effectiveness and efficiency of the justice system was noticed in the Strategy of modernization of justice in Poland in the years 2014–2020 prepared by the Ministry of Justice incorporates the three abovementioned perspectives. From the perspective of this paper, emphasis has been placed on courts. The Strategy, as a matter of fact, assumes that the improvement of the effectiveness and efficiency of courts may occur by introducing a model of management based on the idea of “managerialism” to run them. Effective and efficient courts, just like the proceedings they operate, are particularly important in the face of globalization, regulatory arbitration, as well as forum shopping. Based on a case study, this paper outlines the results of an innovative pilot project of implementing management methods of running common courts, and sets out to answer the question of the extent to which the state of institutional development of courts allows one to employ good practices in courts already successful in the world of business. During the pilot study, in 60 selected regional, district, and appellate courts, with the support of external experts, „good practices” were implemented to serve as management enhancements (Final report…, 2014..). The results of the pilot study prove that the level of institutional development of courts determines the possibility of introducing good management practices that have already been approved in the world of business. This situation is further complicated by the diverse level of institutional development among courts. The type of a given court (its size, regional, district, appellate) may impact the possible upgrade of the maturity of the way a given practice functions. Also, not all business practices are eligible for implementation, given the different level of managers’ competence, as well as the frequently clear process of taking on the management staff.
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Chen, Xiaoyun, M. Anne Leugers, Tim Kirch et Jamie Stanley. « Orientation Mapping of Extruded Polymeric Composites by Polarized Micro-Raman Spectroscopy ». Journal of Spectroscopy 2015 (2015) : 1–7. http://dx.doi.org/10.1155/2015/518054.
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Molecular orientation has a strong influence on polymeric composite materials’ mechanical properties. In this paper we describe the use of polarized micro-Raman spectroscopy as a powerful tool to map out the molecular orientation of a uniaxially oriented polypropylene- (PP-) based composite material. Initial samples exhibited a high degree of surface fibrillation upon cutting. Raman spectroscopy was used to characterize the degree of orientation in the skin and guide the development of the posttreatment process to optimize the skin relaxation while maintaining the high degree of orientation in the rest of the board. The PP oriented polymer composite (OPC) was oriented through an extrusion process and its surface was then treated to achieve relaxation. Micro-Raman analysis at the surface region demonstrated the surface orientation relaxation, and the results provide an effective way to correlate the extent of relaxation and process conditions. Larger scale orientation mapping was also carried out over the entire cross-section (12.7 cm × 2.54 cm). The results agree well with prior expectation of the molecular orientation based on the extrusion and subsequent quenching process. The methodologies described here can be readily applied to other polymeric systems.
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Grimes, David Robert, Alexander G. Fletcher et Mike Partridge. « Oxygen consumption dynamics in steady-state tumour models ». Royal Society Open Science 1, no 1 (septembre 2014) : 140080. http://dx.doi.org/10.1098/rsos.140080.
Texte intégralRésumé :
Oxygen levels in cancerous tissue can have a significant effect on treatment response: hypoxic tissue is both more radioresistant and more chemoresistant than well-oxygenated tissue. While recent advances in medical imaging have facilitated real-time observation of macroscopic oxygenation, the underlying physics limits the resolution to the millimetre domain, whereas oxygen tension varies over a micrometre scale. If the distribution of oxygen in the tumour micro-environment can be accurately estimated, then the effect of potential dose escalation to these hypoxic regions could be better modelled, allowing more realistic simulation of biologically adaptive treatments. Reaction–diffusion models are commonly used for modelling oxygen dynamics, with a variety of functional forms assumed for the dependence of oxygen consumption rate (OCR) on cellular status and local oxygen availability. In this work, we examine reaction–diffusion models of oxygen consumption in spherically and cylindrically symmetric geometries. We consider two different descriptions of oxygen consumption: one in which the rate of consumption is constant and one in which it varies with oxygen tension in a hyperbolic manner. In each case, we derive analytic approximations to the steady-state oxygen distribution, which are shown to closely match the numerical solutions of the equations and accurately predict the extent to which oxygen can diffuse. The derived expressions relate the limit to which oxygen can diffuse into a tissue to the OCR of that tissue. We also demonstrate that differences between these functional forms are likely to be negligible within the range of literature estimates of the hyperbolic oxygen constant, suggesting that the constant consumption rate approximation suffices for modelling oxygen dynamics for most values of OCR. These approximations also allow the rapid identification of situations where hyperbolic consumption forms can result in significant differences from constant consumption rate models, and so can reduce the computational workload associated with numerical solutions, by estimating both the oxygen diffusion distances and resultant oxygen profile. Such analysis may be useful for parameter fitting in large imaging datasets and histological sections, and allows easy quantification of projected differences between functional forms of OCR.
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Yuan, Xianli, Hong Wu, Ping Wang, Fen Xu et Shuang Ding. « Thermal Activation of Coal Gangue with Low Al/Si Ratio as Supplementary Cementitious Materials ». Molecules 27, no 21 (26 octobre 2022) : 7268. http://dx.doi.org/10.3390/molecules27217268.
Texte intégralRésumé :
To effectively utilize coal gangue (CG) with low Al/Si ratio, the thermal activation method was used. The activated CG, as supplementary cementitious materials (SCMs), was added into ordinary Portland cement (OPC) to study its physical properties. The XRD results show that CG undergoes a phase transition from kaolinite to metakaolinite during activation. The NMR tests reveal that the low polymerization state Q3 is continuously broadened, and the Al coordination gradually changes from Al VI to Al V and Al IV. The CG particles are scale-like and glassy with a loose structure. By mixing the activated CG (under 800 °C) with cement (mass ratio = 3:7), the water demand of normal consistency increases by 7.2% and the initial and final setting times extend by 67 min and 81 min, respectively. The rough surface and loose structure of activated CG are the main factors contributing to the higher water demand of normal consistency. The micro-aggregate effect of the activated CG reduces the contact rate between the cement particles and water, and the interparticles, thus slowing down the process of hydration reaction, and leading to longer setting times.
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Edney, M. J., A. L. MacLeod et D. E. LaBerge. « Evolution of a quality testing program for improving malting barley in Canada ». Canadian Journal of Plant Science 94, no 3 (mars 2014) : 535–44. http://dx.doi.org/10.4141/cjps2013-118.
Texte intégralRésumé :
Edney, M. J., MacLeod, A. L. and LaBerge, D. E. 2014. Evolution of a quality testing program for improving malting barley in Canada. Can. J. Plant Sci. 94: 535–544. The quality of Canadian malting barley has continually improved since malt barley was exported in the late 1800s. Improvements were linked to a dynamic evaluation system that evolved with a better understanding of malting biochemistry and as suitable methods were developed. Methods became more accurate and more specific in their ability to define quality. They progressed from sensory evaluation, to surmising malt quality from barley protein levels, to the first micro-maltings followed by automated laboratory-scale maltings. Malt quality analysis started simply with malt extract and diastatic power followed by wort protein. As the necessity for cell wall breakdown became better understood, analyses like wort viscosity, fine/coarse grind extract differences and wort β-glucan were adopted. A continuum of cultivars were released in Canada, based on this evaluation system, starting with the six-rowed releases OAC 21, then Montcalm and Bonanza, followed by the two-rowed releases Betzes, Klages, Harrington and AC Metcalfe. Release of future cultivars will depend on an evolving evaluation system that could include; barley homogeneity, specific starch-degrading enzymes, individual amino acids and specific traits such as low lipoxygenase and low phytic acid barley. The result will be development and release of cultivars with better defined quality that can fill specialized niches in the malting and brewing industries of the future.
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Rawal, D., A. K. Sharma, A. Vyas et A. S. Rajawat. « DEVELOPMENT OF WEB BASED HIMALAYAN GLACIER INFORMATION SYSTEM USING OPEN SOURCE ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W8 (11 juillet 2018) : 181–86. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w8-181-2018.
Texte intégralRésumé :
<p><strong>Abstract.</strong> Systematic inventory of glaciers is required for a variety of applications needed for the comprehensive development of the Himalayan region such as: a) disaster warning, b) estimation of irrigation potential, c) planning and operation of mini and micro hydroelectric power stations, etc.</p><p> A systematic inventory of the Himalayan glaciers at 1<span class="thinspace"></span>:<span class="thinspace"></span>50,000 scale was created for Indus, Ganga and Brahmaputra basins using Indian Remote Sensing Satellite data and attempted to modified global standards in GIS environment (Sharma et al, 2013). A robust, user- friendly web-based Himalayan Glacier Information System (HGIS), a first of its kind in the country is developed which facilitates any user to selectively display, query, analyse, compose maps and graphs and print, spatial and <i>aspatial</i> information on glaciers relevant to respective interests.</p><p> The HGIS architecture is based on Open Geospatial Consortium (OGC) standards and utilises OpenGeo Suite bundled software comprising of Postgresql (PostGIS), Geoserver, GeoWebCache and GeoExplorer each of those having a different function (Anonymous 2010). The spatial and aspatial glacier data sets were stored in a pre-defined format (Sharma et al, 2008) and imbibed into spatially enabled database (PostGIS), having sophisticated functions for spatial data analysis and query. For publishing the data on web page OGC-compliant services are used.</p><p> The HGIS information content comprise of a) glacier inventory maps and b) inventory data sheet. The map displays the glacier morphology features like accumulation zone and ablation (ice exposed and debris covered) zones, snout location, de-glaciated valleys, moraines and glacier lakes. The basin, sub-basin and administrative boundaries form the background. The inventory data sheet attributes for each glacier provides information on glacier Location, Identification, Dimension, Orientation, Elevation, Classification, etc. The spatial map and datasheet are linked by unique glacier identification number (galc_id) which is a key field present in all corresponding glacier related point, polygon or line layers. All the glacier attribute were made amenable to query and analysis by users. HGIS represents a significant step towards mapping and compiling individual glacier level inventory data in spatial form to fill the void in data and information on the status of Glaciers in the Himalaya and Trans-Himalayan Karakoram region. HGIS provides a basis for assessing the glacier inventory data which has applications in studies related to climate change, water resource planning, hydropower site selection and mitigation of glacial lake outburst flood (GLOF) hazards.</p>
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Li, Qiang. « Comprehensive Quantification and Model Optimization of Sports Industry Layout Structure under the Guidance of Location Entropy Intelligent Sensor ». Journal of Sensors 2022 (26 août 2022) : 1–11. http://dx.doi.org/10.1155/2022/9822371.
Texte intégralRésumé :
The field bus control system based on field bus is a multidisciplinary emerging technology with intelligent sensor, automatic control, computer, communication, network, and other technologies as the main content. All have broad application prospects. In this paper, the CAN bus technology in the field bus is combined with the sensor, and the OPC technology is used to realize the acquisition of the underlying data in the application and control system. In this paper, the industry agglomeration model, the leading industry model, the urban gravity model, and its index are calculated, and the agglomeration effect, leading industry, and urban gravity of the sports industry in two provinces and one city in a certain region are judged from the micro level. Location entropy and relative density of technical elements, scale effect function, product income elasticity coefficient, market share, and other economic indicators are compared and described, and the sports leading industry and sports industry growth pole area are deduced, and the corresponding industrial development stage is judged. We analyze the strength of the polarization effect and diffusion effect of the sports industry in the above-mentioned regions. Economic factors, social factors, and traffic road factors are selected to analyze the driving force of the distribution of gymnasiums. According to the results of binary and multivariate correlation analysis, it is found that the gross domestic product is very important to the development of the sports industry and directly determines the regional demand for sports. There are sports industry forms that are clustered in areas with high economic levels; population density is selected as the representative of social factors, and the research results show that population density has a strong correlation with the number of sports industry distributions. The reason is that the development of the sports industry ultimately depends on demand. It is difficult to form a concentrated demand for related sports activities in areas with small population density, so the distribution of the sports industry is also very small; and the transportation factor is the main factor affecting economic development and population flow. Therefore, it also indirectly affects the spatial layout of the sports industry.
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Camporeale, Sergio Mario, Patrizia Domenica Ciliberti, Bernardo Fortunato, Marco Torresi et Antonio Marco Pantaleo. « Externally Fired Micro-Gas Turbine and Organic Rankine Cycle Bottoming Cycle : Optimal Biomass/Natural Gas Combined Heat and Power Generation Configuration for Residential Energy Demand ». Journal of Engineering for Gas Turbines and Power 139, no 4 (8 novembre 2016). http://dx.doi.org/10.1115/1.4034721.
Texte intégralRésumé :
Small-scale combined heat and power (CHP) plants present lower electric efficiency in comparison to large scale ones, and this is particularly true when biomass fuels are used. In most cases, the use of both heat and electricity to serve on-site energy demand is a key issue to achieve acceptable global energy efficiency and investment profitability. However, the heat demand follows a typical daily and seasonal pattern and is influenced by climatic conditions, in particular in the case of residential and tertiary end users. During low heat demand periods, a lot of heat produced by the CHP plant is discharged. In order to increase the electric conversion efficiency of small-scale micro-gas turbine for heat and power cogeneration, a bottoming organic Rankine cycle (ORC) system can be coupled to the cycle, however, this option reduces the temperature and the amount of cogenerated heat available to the thermal load. In this perspective, the paper presents the results of a thermo-economic analysis of small-scale CHP plants composed of a micro-gas turbine (MGT) and a bottoming ORC, serving a typical residential energy demand. For the topping cycle, three different configurations are examined: (1) a simple recuperative micro-gas turbine fueled by natural gas (NG); (2) a dual fuel externally fired gas turbine (EFGT) cycle, fueled by biomass and natural gas (50% share of energy input) (DF); and (3) an externally fired gas turbine (EFGT) with direct combustion of biomass (B). The bottoming ORC is a simple saturated cycle with regeneration and no superheating. The ORC cycle and the fluid selection are optimized on the basis of the available exhaust gas temperature at the turbine exit. The research assesses the influence of the thermal energy demand typology (residential demand with cold, mild, and hot climate conditions) and CHP plant operational strategies (baseload versus heat-driven versus electricity-driven operation mode) on the global energy efficiency and profitability of the following three configurations: (A) MGT with cogeneration; (B) MGT+ ORC without cogeneration; and (C) MGT+ORC with cogeneration. In all cases, a back-up boiler is assumed to match the heat demand of the load (fed by natural gas or biomass). The research explores the profitability of bottoming ORC in view of the following trade-offs: (i) lower energy conversion efficiency and higher investment cost of biomass input with respect to natural gas; (ii) higher efficiency but higher costs and reduced heat available for cogeneration with the bottoming ORC; and (iii) higher primary energy savings and revenues from feed-in tariff available for biomass electricity fed into the grid.
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Jiang, Yanhui, et Hamid Nayeb-Hashemi. « Energy Dissipation During Prey Capture Process in Spider Orb Webs ». Journal of Applied Mechanics 87, no 9 (22 juin 2020). http://dx.doi.org/10.1115/1.4047364.
Texte intégralRésumé :
Abstract Capture of a prey by spider orb webs is a dynamic process with energy dissipation. The dynamic response of spider orb webs under prey impact requires a multi-scale modeling by considering the material microstructures and the assembly of spider silks in the macro-scale. To better understand the prey capture process, this paper addresses a multi-scale approach to uncover the underlying energy dissipation mechanisms. Simulation results show that the microstructures of spider dragline silk play a significant role on energy absorption during prey capture. The alteration of the microstructures, material internal friction, and plastic deformation lead to energy dissipation, which is called material damping. In addition to the material damping in the micro-scale modeling, the energy dissipation due to drag force on the prey is also taken into consideration in the macro-scale modeling. The results indicate that aerodynamic drag, i.e., aero-damping, plays a significant role when the prey size is larger than a critical size.
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ŞEULEANU, Dragoş. « The Communication Dimension of the Business Model Applied to the ELI-NP Project ». Oeconomica 30, no 2 (1 mars 2021). http://dx.doi.org/10.24818/oec/2021/30/2.06.
Texte intégralRésumé :
This paper stems from the conviction that communication via mass-media is very important in order to perform a valuable new business model, taking into consideration that organizations need to cope with sharp changes to their micro and macroeconomic equilibria and with increased intensity in creativity at the level of economic processes, while raising awareness in markets and collecting feedback from stakeholders. The inquiry starts from the hypothesis that, in the field of economics and business, communication approaches must be taken with some reserves for a number of reasons: functional markets have their infrastructural specificities; public choice logic is undisputedly widespread; the concept of social learning is present much more than in other fields; and the very principle of economic rationality possesses many competing off-springs and off-shoots. As the proposed analysis is undertaken in the confines of education systems, scientific research and high-tech industries, it is pointed out the fact that an advanced research project with international impact, such as the Extreme Light Infrastructure - Nuclear Physics project (ELI-NP), will be an extremely important driver of the national and regional economies, needing a communicational strategy to complement and consolidate the informational flows of purely technical-scientific nature between specialists, thus enlarging the scale and scope for the dissemination of both efforts and results.