Search results for "Energy engineering"
showing 10 items of 1099 documents
DEMAND Project: Bottom-Up Aggregation of Prosumers in Distribution Networks
2018
The paper explains the concept of the DEMAND project, whose aim is to develop a technical framework for allowing a Bottom-Up aggregation of prosumers connected to the distribution grid. Load and generation aggregation is a very current issue given the great potential that the coordinated management of distributed resources has on power systems operation and design. The novelty in DEMAND is the absence of a physical aggregator and the recourse to a virtual aggregation environment (VAE) for allowing the exchange of information among the prosumers in order to provide a service to the DSO. After a general description of the research project, the paper presents the services that the aggregated c…
A Review of Key Performance Indicators for Building Flexibility Quantification to Support the Clean Energy Transition
2021
The transition to a sustainable society and a carbon-neutral economy by 2050 requires extensive deployment of renewable energy sources that, due to the aleatority and non-programmability of most of them, may seriously affect the stability of existing power grids. In this context, buildings are increasingly being seen as a potential source of energy flexibility for the power grid. In literature, key performance indicators, allowing different aspects of the load management, are used to investigate buildings’ energy flexibility. The paper reviews existing indicators developed in the context of theoretical, experimental and numerical studies on flexible buildings, outlining the current status a…
Wave Energy Assessment around the Aegadian Islands (Sicily)
2019
This paper presents the estimation of the wave energy potential around the Aegadian islands (Italy), carried out on the basis of high resolution wave hindcast. This reanalysis was developed employing Weather Research and Forecast (WRF) and WAVEWATCH III ® models for the modelling of the atmosphere and the waves, respectively. Wave climate has been determined using the above-mentioned 32-year dataset covering the years from 1979 to 2010. To improve the information about wave characteristics regarding spatial details, i.e., increasing wave model resolution, especially in the nearshore region around the islands, a SWAN (Simulating WAves Nearshore) wave propagation model was used. Results obtai…
A stochastic approach for self-healing capability evaluation in active islanded AC/DC hybrid microgrids
2023
This paper aims to implement a resilience assessment in AC/DC hybrid microgrids using a stochastic simulation approach. Self-healing measures including load shedding, control of distributed generation and flexible devices, like Energy Storage Systems (ESS) and Electrical Vehicles (EVs), are simulated to enable AC/DC hybrid microgrids to supply critical loads in islanded mode, assuming a disconnection of these microgrids from the main AC grid due to a fault. To perform this analysis, a two-stage process is proposed: first, a Monte-Carlo simulation-based stochastic approach is adopted to generate samples to simulate intermittent loads, power generation from Renewable Energy Sources (RESs), an…
Flow Theory and Online Marketing Outcomes: A Critical Literature Review
2013
Abstract The aim of this paper is to provide a critical review of flow theory - a psychological state - and its marketing outcomes in online environments. Despite the strong interest of researchers from various disciplines, adapting the flow theory to online environments has been problematic. Based on a careful examination of the literature, we identified conceptual challenges confronted when studying flow online. The paper further discusses some possible solutions for challenges and underlines the need for more studies in this research area. Finally, marketing outcomes of applying flow theory in online environment were examined.
Electric Field Effect on the Thermal Decomposition and Co-combustion of Straw with Solid Fuel Pellets
2019
The aim of this study was to provide more effective use of straw for energy production by co-firing wheat straw pellets with solid fuels (wood, peat pellets) under additional electric control of the combustion characteristics at thermo-chemical conversion of fuel mixtures. Effects of the DC electric field on the main combustion characteristics were studied experimentally using a fixed-bed experimental setup with a heat output up to 4 kW. An axisymmetric electric field was applied to the flame base between the positively charged electrode and the grounded wall of the combustion chamber. The experimental study includes local measurements of the composition of the gasification gas, flame tempe…
Conversion of peat and coal nitrogen through HCN and NH3 to nitrogen oxides at 800 °C
1993
The conversion of fuel nitrogen through HCN and NH3 to nitrogen oxides (N2O, NO and NO2) was studied using an entrained-flow reactor at 800 °C with one coal and four peats at 5 and 1% O2. The ON ratios of the fuels were between 7 and 20. A clear dependence was found between the HCNNH3 ratio measured just after the vigorous pyrolysis step and the N2ONO ratio in the flue gas when these were plotted as a function of the initial ON ratio of the fuel.
Towards controlling PCDD/F production in a multi-fuel fired BFB boiler using two sulfur addition strategies. Part I: Experimental campaign and results
2014
Abstract Levels of PCDD/F production in a 140 MW th bubbling fluidized bed boiler were measured. The boiler uses solid recovered fuel, bark and sludge. Homologue distribution patterns suggest the de novo mechanism is the main pathway for the generation of dioxin and furans in the post combustion zones of the boiler. Two modes of sulfur addition were tested to induce the deactivation of Cu which has been identified as the prime catalyst of this mechanism. First, S-pellet promoted Cu sulfation as supported by aerosol sampling data and resulted in a decrease in PCDD/F levels. The second approach was adding sulfur through peat; this resulted in an increase in PCDD/F concentration. Factors such …
Absence of correlated flux pinning by columnar defects in irradiated epitaxial Bi2Sr2CaCu2O8 thin films
1999
Abstract Using heavy-ion irradiation, we produced columnar defects of different density and orientation in epitaxial Bi 2 Sr 2 CaCu 2 O 8 thin films. Although this increases the normal state resistivity and the critical temperature is reduced proportionally to the volume fraction of damaged material, pinning-related quantities like critical current density, activation energy and depinning field are enhanced in external magnetic fields. Transport measurements in dependence of the magnetic field and its orientation consistently indicate two-dimensional pinning of pancake vortices at the columnar defects. We observe the absence of correlated flux pinning by columnar defects and compare to heav…
Dynamic modelling of a quadratic DC/DC single-switch boost converter
2017
This manuscript proposes the analysis of a Quadratic Boost Converter (QBC) transformer-less single switch typology. The state space average dynamic model and a constrained state space average model taking into account the mono-directional components of the converter (diodes, switches) have been analyzed. The static gain expression taking into consideration the parasitic elements of the converter and the small-signal transfer function of the QBC typology under study has been obtained. A sensitivity analysis has shown a high variation of the gain versus duty-cycle and of the derivative gain versus parasitic parameters of the converter in the range of the duty-cycle from 0.6 to 0.8 which is ra…