1,721,094 research outputs found
Influence parameters on the photovoltaic modules performance
No full textIn this work the authors propose an experimental and numerical investigation of the dependence of temperature and efficiency of photovoltaic modules on main design parameters (thickness of the aluminium frame, etc.), installation technique (distance between photovoltaic panel and supporting panel, tilt angle of the module), and environmental operating conditions, with particular reference to the wind velocity. The main objective of the present paper is to provide installation and operating indications in order to maximize efficiency. From the conducted investigations it has been evidenced that an optimal distance of the panel from the support can be found, in correspondence of which the efficiency is maximized
Experimental design techniques for optimising measurement chain calibration
No full textThis paper tackles the design of a calibration using experimental design techniques. In particular, the optimum calibration plan for measurement chain is identified by suitably elaborating the error propagation law suggested by the ISO Guide. The main advantages of the proposed approach consist in: (i) calibration plans with a reduced number of calibration points; (ii) calibration curve applicable to the whole operating range; (iii) linear rather than complex regression technique always usable. Two different cases were analysed in order to show the efficiency of the proposed optimisation procedure: a psychrometer and an heat meter. The obtained theoretical results are verified on a number of real calibrations. © 2001 Published by Elsevier Science Ltd
Simplified analytical methods for evaluating the pressure distortion coefficient of controlled-clearance pressure balances
No full textSeveral numerical and empirical methods are used to design and characterise pressure balances, but most of them are not applicable to complex units. Here, a simplified analytical method developed at the University of Cassino is reported. This method can be used to evaluate the pressure distortion coefficient of complex pressure balances used in the high-pressure range with particular reference to controlled-clearance pressure balances constructed from different materials. The results obtained by the proposed method are compared with experimental and numerical data relating to different controlled-clearance pressure balances
Experimental and numerical assessment of photovoltaic collectors performance dependence on frame size and installation technique
No full textThe performance of a solar photovoltaic silicon panel is inversely proportional to its operating temperature. Therefore the overheating risk must be avoided in order to improve the cells electric efficiency. The temperature increase in a solar cell also gives rise to thermal stresses within the module. In this work the authors propose an experimental and numerical investigation of photovoltaic collectors temperature and efficiency dependence on main design parameters (thickness of the aluminum frame), installation technique (distance between photovoltaic panel and supporting panel, tilt angle of the module), and environmental operating conditions, with particular reference to the wind velocity. Experimental investigations have been conducted on a two photovoltaic modules assembly composed by silicon panels. Numerical simulations have been performed employing a two-dimensional finite element numerical model, validated against experiments carried out by the authors. The validated numerical tool has been applied to evaluate photovoltaic collector performance dependence on panel geometrical parameters, installation procedure and operating conditions. The main objective of the present paper is to provide installation and operating indications in order to maximize efficiency. From the conducted investigations it has been evidenced that an optimal distance of the panel from the support can be found, corresponding to which the efficiency is maximized
Analysis of the operating strategy of a SOFC based unit for thermal and electric residential loads
No full textIn order to bring High Temperature Fuel Cells (HT-FCs) on the market, on-site experiments are crucial to understand HT-FCs based units performance and their actual applicability to residential power generation. The authors present here the results of recent experimental and numerical analysis conducted on a micro-cogenerative Solid Oxide Fuel Cells (SOFCs) based unit. A new measurement system has been designed by the authors on the basis of an a-priori uncertainty analysis, and additional meters have been installed in order to perform an a-posteriori uncertainty analysis. Effective application of HT-FCs to residential use has been studied using the validated numerical model developed by the authors in order to follow electric and thermal loads, and technical and economic analysis have been carried out
Prestazioni acustiche passive degli edifici in Sardegna: analisi dei risultati ottenuti nell’ultimo quinquennio su fabbricati nuovi e ristrutturati nei principali capoluoghi della regione Sardegna
No full textLa Sardegna è una delle poche regioni d’Italia dove a seguito della DGR 62/9 del 2008 è obbligatoria la progettazione dei requisiti acustici passivi per le nuove costruzioni e per le ristrutturazioni. Molte cause legali, che hanno ad oggetto il rumore ed in particolare i requisiti acustici passivi, promosse da acquirenti di unità immobiliari nuove o ristrutturate, portano a pensare che la delibera regionale sia rimasta negli anni inapplicata. IL presente lavoro analizza un insieme di dati ricavati da misurazioni in situ, eseguite negli ultimi cinque anni su tutto il territorio regionale secondo gli standard UNI di riferimento, allo scopo di fare una panoramica sul rispetto in opera dei requisiti acustici passivi. Nella campagna di misura si sono verificate diverse tipologie di costruzioni, nuove e ristrutturate, si sono determinati i diversi indicatori prestazionali e si sono confrontati in fine questi con i limiti previsti dal DPCM 5/12/97
Numerical analisys of flow conditioner efficiency
No full textThe use of flow conditioners becomes necessary in flow measurement applications where the geometry of conduits does not allow complete development of the velocity profile upstream the flowmeter. In this paper the authors present a numerical analysis, based on finite volume technique, for the evaluation of flow conditioner performance under low level perturbation conditions. The use of non structured grids was necessary because of the complexity of the geometry studied. The results of the numerical calculations were used to evaluate the efficiency of different types of flow conditioners. The efficiency was defined on the basis of different parameters that take into account flatness, uni-directionality and asymmetry of the velocity profile downstream the flow conditioner
"BIM AND PLANT SYSTEMS: A SPECIFIC ASSESSMENT"
Full text linkIt is now known that the use of Building Information Modeling (BIM) procedures offers many benefits in the design and management of buildings. According to recent legislative enactments the BIM procedures will become mandatory for Public Works as from 2019. There are several advantages by using BIM procedures, among them the following can be highlighted: gaining a clear overview of the building plant system, evaluating the spatial coherence of the plant networks, the evaluation of the interferences to keep the system do not interfere with the functionality or the aesthetics of built environments. The present work analyzes the BIM procedures with particular reference to air conditioning systems in existing buildings, to their performance and management characteristics. The objective consists of analyzing the different BIM procedures and critically comparing the information provided by the IFC standard published by the European Institution Building SMART International, recognised as a standard by ISO, with the main reference standards for building installations and facilities design
The energetic characterization of solar-control environments
Full text linkDespite the increasingly pressing regulations in the energy sector (EPBD recast, law 90/2013 and the consequent decree 162 of 2015), which push towards policies and financial measures to promote buildings with almost zero energy, the quality of the internal environment remains one of the critical parameters on which to pay more attention in view of a consistent evaluation of the Nzeb building. The authors show, in the present paper, the results related to the energetic characterization of two test rooms, identical for surface and opaque envelope, but with different typologies of windows on the South-East and South-West wall
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