Search results for "Operating temperature"
showing 10 items of 22 documents
Wireless partial discharge tracking on cross-linked polyethylene MV and HV cables
2018
Medium voltage (MV)/high voltage (HV) cable lines are high-value assets and require substantial costs for their installation or replacement. For this reason, the capability to assess the condition of cable lengths and accessories on site is of great importance. Cross-linked polyethylene (XLPE) insulation is extensively used for MV, HV, and extra-high voltage (EHV) class cables [1] thanks to its excellent voltage-endurance and thermomechanical properties. In particular, XLPE-insulated cables feature substantially lower losses, easier manufacturing and jointing procedures, better environmental compatibility, and higher operating temperature compared with impregnated paper cables, which lead t…
A study of solar thermal absorber stack based on CrAlSiNx/CrAlSiNxOy structure by ion beams
2019
Renewable energies are foreseen as a major energy resource for next generations. Among several energy sources and technologies available, Concentrated Solar Power (CSP) technology has a great potential, but it needs to be optimised, in particular to reduce the costs, with an increase of the operating temperature and long term stability. This goal can be achieved by tailoring the composition and multilayer structure of films. In this work we present and discuss the results obtained from solar absorber coatings based on nitride/oxynitride structures. A four-layer film structure, W/CrAlSiNx(HA)/CrAlSiNxOy(LA)/SiAlOx, was deposited on stainless steel substrates using magnetron sputtering deposi…
Equivalent cell temperature calculation for PV modules with variable ideality factors
2012
Outdoor testing of PV modules involves monitoring their operating temperatures which have strong influence on the output power. Back-of-module sensing is associated with significant uncertainty due to temperature drop across the back encapsulation and also due to non-uniform temperature over the module's area. The international standard IEC 60904-5 defines a procedure for calculating the Equivalent Cell Temperature (ECT) of PV devices from their open-circuit voltage. This and other standards (as well as some module performance models) assume a single-exponential I-V curve model with a constant ideality factor. However, this parameter may vary with the illumination level and the operating te…
Energy management of a thermally coupled fuel cell system and metal hydride tank
2019
International audience; Being produced from renewable energy, hydrogen is one of the most efficient energy carriers of the future. Using metal alloys, hydrogen can be stored and transported at a low cost, in a safe and effective manner. However, most metals react with hydrogen to form a compound called metal hydride (MH). This reaction is an exothermic process, and as a result releases heat. With sufficient heat supply, hydrogen can be released from the as-formed metal hydride. In this work, we propose an integrated power system of a proton exchange membrane fuel cell (PEMFC) together with a hydride tank designed for vehicle use. We investigate different aspects for developing metal hydride…
Optimizing the operating temperature of a transition edge sensor
2006
We discuss the theory for optimizing the operating temperature of a voltage biased superconducting transition edge sensor (TES) in terms of energy resolution and speed, considering only internal detector noise sources. The noise processes included in the modeling are the unavoidable Johnson and phonon noise. The phonon noise is calculated for the case of ballistic transport. If other external and excess internal noise sources are not dominant, an optimal operating temperature can be found to minimize the energy resolution. The detector slows down by approximately a factor of two at the optimal energy resolution point.
A single stage adiabatic demagnetization refrigerator for testing x-ray microcalorimeters
2004
A single stage Adiabatic Demagnetization Refrigerator (ADR), has been set-up at the X-ray Astronomy Calibration and Testing (XACT) facility of INAF - Osservatorio Astronomico di Palermo G.S. Vaiana, for the development and testing of cryogenic X-ray detectors for laboratory and astrophysical applications. The ADR allows to cool detectors at temperatures below 40 mK and to maintain them at constant operating temperature for many hours. We describe the design and construction of the ADR and present test results and performances.
Relative efficiency revealed: Equations for k<inf>1</inf>&#x2013;k<inf>6</inf> of the PVGIS model
2014
The European PV Geographical Information System (PVGIS) describes module performance in terms of the relative efficiency with respect to Standard Testing Conditions (STC). The efficiency's dependence on irradiance and operating temperature is modeled with a bi-quadratic polynomial with respect to the relative temperature and the logarithm of relative irradiance. In earlier works, the present author derived relations between two model coefficients describing the irradiance dependence at 25°C, k 1 and k 2 , and I–V curve model parameters such as the series resistance RS and the ideality factor n. There was good agreement between the theoretical and fitted values of k 1 , but the fitted values…
SPICE model for resistive gas and odour sensors
1999
A generalised PSPICE model of resistive gas/odour sensors is presented. The model simulates the response of both polymeric and metal oxide devices, as well as an integrated resistive heater that is used to set the operating temperature. In both cases there was good agreement between the observed responses and the PSPICE simulated responses to rectangular pulses of gases. The PSPICE model is not only simpler and faster to use than analytical solutions, but also should permit the rapid prototyping of associated drive circuitry.
ANN modelling of CO2 refrigerant cooling system COP in a smart warehouse
2020
Author's accepted manuscript Industrial cooling systems consume large quantities of energy with highly variable power demand. To reduce environmental impact and overall energy consumption, and to stabilize the power requirements, it is recommended to recover surplus heat, store energy, and integrate renewable energy production. To control these operations continuously in a complex energy system, an intelligent energy management system can be employed using operational data and machine learning. In this work, we have developed an artificial neural network based technique for modelling operational CO2 refrigerant based industrial cooling systems for embedding in an overall energy management s…
Forecasting the Cell Temperature of PV Modules with an Adaptive System
2013
The need to reduce energy consumptions and to optimize the processes of energy production has pushed the technology towards the implementation of hybrid systems for combined production of electric and thermal energy. In particular, recent researches look with interest at the installation of hybrid system PV/T. To improve the energy performance of these systems, it is necessary to know the operating temperature of the photovoltaic modules. Furthermore, when photovoltaic (PV) systems replace the traditional building envelope materials and they are fully integrated (building integrated photovoltaic (BIPV)), it is very important to correctly assess their thermal behaviour. The determination of …