Search results for " Cooling"
showing 10 items of 278 documents
Crushing of interstellar gas clouds in supernova remnants II. X-ray emission
2006
AIMS. We study and discuss the time-dependent X-ray emission predicted by hydrodynamic modeling of the interaction of a SNR shock wave with an interstellar gas cloud. The scope includes: 1) to study the correspondence between modeled and X-ray emitting structures, 2) to explore two different physical regimes in which either thermal conduction or radiative cooling plays a dominant role, and 3) to investigate the effects of the physical processes at work on the emission of the shocked cloud in the two different regimes. METHODS. We use a detailed hydrodynamic model, including thermal conduction and radiation, and explore two cases characterized by different Mach numbers of the primary shock: …
Hydrodynamic Modeling of Accretion Impacts in Classical T Tauri Stars: Radiative Heating of the Pre-shock Plasma
2016
Context. It is generally accepted that, in classical T Tauri stars, the plasma from the circumstellar disc accretes onto the stellar surface with free-fall velocity and the impact generates a shock. The impact region is expected to contribute to emission in different spectral bands; many studies have confirmed that the X-rays arise from the post-shock plasma but, otherwise, there are no studies in the literature investigating the origin of the observed UV emission which is apparently correlated to accretion. Aims: We investigated the effect of radiative heating of the infalling material by the post-shock plasma at the base of the accretion stream, with the aim to identify in which region a …
Monitoring Program of Small-Scale Solar Heating and Cooling within IEA-SHC Task 38 – Procedure and First Results
2010
Within IEA-SHC Task 38 (Solar Air Conditioning and Refrigeration), a monitoring procedure for solar heating and cooling systems was developed. This methodology includes measurements of all relevant energy flows (heat, cold, electricity) to be able to derive key figures such as primary energy ratio, electrical coefficient of performance, solar heat management efficiency, fractional savings for heating and cooling compared to a conventional (non solar) heating and cooling system. A number of small-scale systems for solar heating and cooling are currently being monitored across Europe. For a handful of systems monitoring data of at least a full year of operation is already available. These sys…
Exergetic and exergoeconomic analysis of a renewable polygeneration system serving a small isolated community
2014
A great interest has been arising in the last decade for the sustainable supply of energy and fresh water, also due to the rapidly growing demand from developing countries. Facing this demand by traditional technologies and fossil energy sources implies evident difficulties and risks, because of the scarcity and high cost of fuels and their relevant environmental impact in terms of local pollution and global warming emissions. Then, the efforts of researchers have been focusing on alternative solutions, either based on the use of renewable energy sources and on innovative plant schemes for the combined and efficient production of several energy and material flows. In this paper an innovativ…
A novel solar trigeneration system integrating Photovoltaic/Thermal collectors and seawater desalination: dynamic simulation and economic assessment
2013
This paper investigates the integration of renewable energy sources and water systems, presenting a novel solar system producing simultaneously: electrical energy, thermal energy, cooling energy and domestic water. The polygeneration system under analysis includes photovoltaic/thermal solar collectors (PVT), a multi-effect distillation (MED) system for seawater desalination, a single-stage LiBr-H2O absorption chiller and additional components, such as storage tanks, auxiliary heaters and balance of plant devices. The PVT produces simultaneously electrical energy and thermal energy, at a maximum temperature of about 100 °C. The electrical energy is delivered to the grid, whereas the thermal …
On the Derivation of the Boiling Curve in Spray Cooling from Experimental Temperature-Time Histories
2006
Optimization of the breeder zone cooling tubes of the DEMO Water-Cooled Lithium Lead breeding blanket
2016
Abstract The determination of an optimal configuration for the breeder zone (BZ) cooling tubes is one of the most important issues in the DEMO Water-Cooled Lithium Lead (WCLL) breeding blanket R&D activities, since BZ cooling tubes spatial distribution should ensure an efficient heat power removal from the breeder, avoiding hotspots occurrence in the thermal field. Within the framework of R&D activities supported by the HORIZON 2020 EUROfusion Consortium action on the DEMO WCLL breeding blanket design, a campaign of parametric analyses has been launched at the Department of Energy, Information Engineering and Mathematical Models of the University of Palermo (DEIM), in close cooperation with…
A facile semi-open method for synthesis of non-centrosymmetric superconducting Li2(Pd,Pt)3B bulks and thin films
2010
Abstract Non-centrosymmetric superconductor Li 2 (Pd 1− x Pt x ) 3 B, x = 0–1 was synthesized from mixtures of the elements. A simple semi-open method is proposed using endings-pressed stainless steel tubes placed in a high-vacuum furnace. Heating regime employed a short-time overheating at 900 °C and a slow cooling step between T s and 550 °C within 3 h. To adequately compensate Li-losses and attain maximum critical temperature, the optimum T s and starting Li-content were found to change from 720 to 740 °C and from Li 2.4 to Li 2.6 , respectively, when x was changing from 0 to 1. It was shown that placing Li separately in the tube also produces superconducting samples, Li being supplied …
Microrefrigeration by quasiparticle tunnelling in NIS and SIS junctions
2000
Abstract A solid-state refrigeration method at sub-kelvin temperatures has been developed. It is based on quasiparticle tunnelling between a superconductor and a normal metal, or, between two dissimilar superconducting metals. The refrigerator is fabricated by combining nanolithography and micromachining methods. This technique has been demonstrated in both electron cooling from 0.3 to 0.1 K and in refrigeration of a dielectric platform. We describe a new fabrication method of tunnel junctions in a shadow evaporation configuration using a mechanical mask of silicon nitride.
Application of superconductor-semiconductor Schottky barrier for electron cooling
2003
Abstract Electronic cooling in superconductor–semiconductor–superconductor structures at sub kelvin temperatures has been demonstrated. Effect of the carrier concentration in the semiconductor on performance of the micro-cooler has been investigated.