Search results for "Cooling"

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 …

Thermoanalytical studies on phases of D-mannitol

1993

Abstract D-mannitol exists in several polymorphic crystalline forms. The conditions of crystallization are not well-defined, and in some cases mixtures of the different forms are obtained. In the DSC study the different forms melted nearly at the same temperature (166±°C). The heat of fusion of the k form was lower than those of the other forms. With slow heating rate (2 ° C min ) the δ form changed to k between 140 and 165 °C. The crystallization of D-mannitol from the melt gave from one to seven peaks in the DSC between 95 and 126 °C depending on cooling rates and the amounts of sample.

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 …

Correlation of primary relaxations and high-frequency modes in supercooled liquids. II. Evidence from spin-lattice relaxation weighted stimulated-ech…

2006

Using spin-lattice relaxation weighted stimulated-echo spectroscopy, we report evidence for a correlation of the primary and secondary relaxation times. The experiments are performed using deuteron nuclear magnetic resonance somewhat above the calorimetric glass-transition of ortho-terphenyl, D-sorbitol, and cresolphthalein-dimethylether. The data analysis is based on the procedure outlined in the accompanying theoretical paper [B. Geil, G. Diezemann, and R. B\"ohmer, Phys. Rev. E 74, 041504 (2006)]. Direct experimental evidence for a modified spin-lattice relaxation is obtained from measurements on a methyl deuterated acetyl salicylic acid glass. The limitations of the present experimental…

On the Derivation of the Boiling Curve in Spray Cooling from Experimental Temperature-Time Histories

2006

Comment on "Ecological importance of the thermal emissivity of avian eggshells".

2012

Eggshell emissivity must be known to determine accurately the cooling rate of avian eggs when the parent, after heating by conduction during the incubation, is temporarily absent. We estimate possible values of eggshell emissivities from in-situ measurements and spectral libraries. Emissivity is near to 1 (probably higher than 0.95) and therefore its effect on cooling rate may be negligible, with differences between the temperature of the egg assuming a value of e=0.95 and that of a blackbody (e=1) below 0.2 °C.

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…