Search results for " Tecnica"
showing 10 items of 2030 documents
An agent-based model to support the preliminary design and operation of heating and power grids with cogeneration units and photovoltaic panels in de…
2022
The increase in the energy demands of residential neighborhoods constitutes a huge challenge to be faced. A viable option lies in the insertion of both renewable energy production systems and cogeneration units within urban territories. On-site production allows for the satisfaction of the heating and electrical demands of end-users and favors the distribution of produced energy within the neighborhood, especially under the regulatory framework of energy communities. This paper proposes a tool to model heating and electricity networks integrated with cogeneration units and PV panels installed in urban areas. The tool accounts for the following possibilities: (i) energy flow management and p…
Green geopolymeric concrete using grits for applications in construction
2018
Abstract This work investigates the production a green geopolymer-based concrete for a sustainable construction material using biomass wastes from a kraft pulp industry: fly ash (as main alumina-silicate source) and grits (as aggregate). Moreover, a simple, reproducible, ambient temperature, and low-cost manufacture is followed. Mix design aims to maximize wastes incorporation and optimize the mechanical performance. Preliminary tests indicate that the used wastes may be successfully employed to produce green geopolymeric concretes with satisfying mechanical performance (up to 18 MPa), according to the European standards. Furthermore, they represent a viable solution to reduce the environme…
An experimental investigation on air quality inside WindJet aircraft
2012
ABSTRACT In order to improve the passengers and crew comfort during the flight, the aim of the present paper is a study of the cabin air quality through experimental measures on randomly selected flight segments of an Italian airline company, WindJet. Carbon dioxide, ultrafine particles, temperature and relative humidity have been measured by using low cost high efficiency instrumental equipments. Exploring ways to improve aircraft cabin air quality, WindJet and University of Palermo are investigating equipment, filters and components of the ventilation system. In this paper, after description of both ventilation systems for aircrafts of WindJet and the instrumental equipments used to measu…
Effects of Air Tightness Tests on Steel Thin-Wall Box Structures with Circular and Rectangular Cross Sections
2019
In this paper, the effects of air tightness tests on steel box structures with rectangular or circular cross sections typical of port cranes (legs, arms, and crosspieces) are analyzed. Legs and arms are generally made with elements with profiles having a square or rectangular cross section, while the diagonal struts are made with profiles having circular cross sections. To verify the air tightness of these elements, a necessary requirement to protect them from corrosion if they are not protected with other protection techniques, air tightness tests are performed. These tests, in the framework of durability tests, must be carried out while maintaining the structure elasticity well below the …
Experimental characterization of variable-speed packaged rooftop units in presence of evaporator fouling
2022
Variable-speed packaged rooftop units have been increasingly adopted in the commercial sector. If not properly maintained, the fouling of heat exchangers and the improper refrigerant charge could increase energy consumption. In this work, the response of variable-speed rooftop units to evaporator fouling is investigated based on experiments on a variable-speed 17.5 kW rooftop unit. A novel testing procedure is proposed, aimed at covering a broad range of operating conditions by a reduced number of tests. Two opposite cases were investigated: (i) even in presence of fouling, the controller can restore the required cooling capacity, and (ii) the intensity of the fouling does not allow the con…
Margini e interstizi vegetati per una città resiliente
2021
La mancanza di vegetazione all’interno delle nostre città e, soprattutto, dei centri storici determina oggi, alla luce dei cambiamenti climatici in corso, notevoli problematiche tra le quali vanno annoverate – tra quelle più gravi – l’impossibilità di contrastare efficacemente le ondate di calore, sempre più frequenti in ambito Mediterraneo, con conseguente aumento dei consumi energetici degli edifici dovuti alla necessità di garantire il comfort indoor e l’incapacità di rallentare il deflusso delle acque meteoriche che a causa degli eventi di pioggia estremi e dell’impermeabilità dei suoli rendono sempre più inefficaci i sistemi di drenaggio urbano esistenti. L’utilizzo della vegetazione c…
An improved algorithm for thermal dynamic simulation of walls using Z-transform coefficients
2003
The Transfer Function Method (TFM), recommended by American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), is one of the most modern tools available to solve heat transfer problems in building envelopes and environments. TFM utilises Z-transform to solve the equations system that describes the heat transfer in a multi-layered wall. Due to an analogy with an electric circuit, it is possible to write the equations system in a matrix suitable to be solved by computer. Authors carried out an analysis on an historical building placed in the south of Italy to test the reliability and the quality of the thermal dynamic simulation using TFM. The analysis is performed usi…
Templated growth of smart nanocomposite thin films: Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition of vanadyl acetylacet…
2009
Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition methodology has been utilised to produce nanocomposite thin films of gold nanoparticles and vanadium dioxide from vanadyl acetylacetonate and auric acid. The addition of tetraoctyl ammonium bromide (TOAB) to the precursor Solution gave control of the size and distribution of gold nanoparticles in the vanadium oxide matrix. These reactions led to vanadium dioxide films with reduced crystallite sizes and enhanced thermochromic properties. The films were analysed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. Their optical and thermochromic behaviour was also determined, This h…
A procedure to calculate the I–V characteristics of thin-film photovoltaic modules using an explicit rational form
2015
Abstract Accurate models of the electrical behaviour of photovoltaic modules are effective tools for system design. One or two diode equivalent circuits have been widely used even though some mathematical difficulties were found dealing with implicit equations. In this paper, a new model based on a simple rational function, which does not contain any implicit exponential form, is presented. The model was conceived in order to be used with thin-film photovoltaic modules, whose current–voltage curves are characterised by very smooth shapes. The parameters of the model are evaluated by means of the derivatives of the issued characteristics in the short circuit and open circuit points at standa…
An accurate one-diode model suited to represent the current-voltage characteristics of crystalline and thin-film photovoltaic modules
2020
Abstract In this paper a new one-diode model, conceived in order to be used to represent the current-voltage curves of both crystalline and thin-film photovoltaic modules, is presented. The model parameters are calculated from the information contained in the datasheets issued by manufactures by means of simple iterative procedures that do not require the assumption of simplifying hypotheses. Some innovative relations describing the dependence of the parameters from the solar irradiance and cell temperature are adopted in order to permit the model to reliably simulate the electrical behaviour of photovoltaic devices operating in real conditions. The ability of the model to calculate the cur…