Search results for "Thermal energy"
showing 10 items of 126 documents
The role of transportation and its involved sources of energy in the environmental assessment of marble producing sites
2018
Marble is acquiring large popularity as building material. Since building materials are now required to be characterized by high energy and environmental performances, marble is entailed to fulfill top-level requirements. About its environmental performances an important European Decision establishes criteria for the award of the Community eco-label to this material. Unfortunately, this Decision is focused on mining and processing activities, seemingly neglecting marble transport. In contrast, this phase affects the whole working chain because it releases (pollutant) emissions and involves the use of primary and, in case, secondary energy sources. Here, the focus is on the role played by tr…
Volcanic steam output directly measured in fumaroles: the observed variations at Vulcano Island, Italy, between 1983 and 1987
1992
The mass of steam emitted by the fumaroles of the crater of Vulcano (Aeolian Islands, Italy) was evaluated by using a direct measuring method. Measurements were effected with this method between 1983 and 1987 in nine field campaigns, the results of which are given in this paper. The steam flux measurements were performed by an instrument expressly designed for steam condensation. The estimates of the thermal energy transported daily by the steam gave values of up to 10E12 J. The sharp variations in the total mass outputs recorded in 1984 and 1985 are here interpreted as being a consequence of the probable accumulation of fluid pressure at depth, during the evolution of volcanic activity. Th…
Reducing Electric and Thermal Energy Needs in Buildings by Using Innovative Envelope Materials
2018
The life style of building occupants is continuously arising towards conditions that are more comfortable involving, on turn, the growing of the electric energy consumptions for climatization purposes. This calls for the improvement of the efficiencies of equipment along with environmental performance of building materials. Laboratory analyses of samples of mixed materials, utilizing tomato stems harvested in Sicily and Cataluna, have been conducted Thermal conductance and mechanical properties have been detected for different rates of bio-component and inert materials. First results of the thermal properties seem to situate such bio-composites among the insulating building materials, for a…
Sustainable technologies for greenhouse systems
2020
The greenhouse cultivation system in European countries represents one of the most energy-intensive sectors in the agriculture and agro-industry sector. In this regard, renewable energies represent an innovative solution to reduce energy costs and environmental impacts. Both, the energy demands and the economic aspects are analyzed with regard to the main energy users, i.e.: heating and cooling systems, lighting and pumping for irrigation. This work considers the use of solar photovoltaic and thermal energy. The use of semi-closed greenhouses is also considered.
The carrier-loaded helium-jet transport method
1974
Abstract The suitability of commercial helium loaded with small amounts of different gases or vapors for the transport of radioactive reaction products over distances of several meters has been investigated experimentally. Negative results were obtained with gaseous carriers. Transport efficiencies of 50 to 100% were obtained with carrier vapors. The vapor appears to form droplets in the system. The recoils are adsorbed physically by the droplets and carried with them through a capillary. There appears to be an active mechanism that forces the heavy constituents to the centre of the capillary cross section. The heavy constituents emerge from the capillary as a very narrow beam. Collection o…
Zeolite-gas systems and solar refrigeration : a study of the adsorptive properties at high pressures in the R22 freon-13X zeolite and ammonia-13X zeo…
1990
The adsorption of ammonia and R22 freon on 13X zeolite was studied in the conditions of possible use of these fluids in heat machines for solar refrigeration. The ranges of temperature and pressure, investigated in this study, extended from 0 to 80 °C and from 10-1 to 6 105 Pa respectively. The adsorption isotherms were collected by microgravimetry using a thermobalance specially built to be used in aggressive gases at pressures up to 106 Pa. Weak hysteresis was detected when ammonia was desorbed below 80 °C. A critical study concerning both applicability of classical adsorption equations (Dubinin-Radushkevitch and Langmuir) and comparison with other zeolite-gas systems is presented. Compar…
Environmental assessment of a waste-to-energy practice: The pyrolysis of agro-industrial biomass residues
2021
Abstract The bio-wastes pyrolysis is a waste to energy strategy that converts bio-wastes into valuable products (bio-char, bio-oil) with wide use in the agri-food sector. However, limited efforts are paid to the investigation of its environmental sustainability: in this context, the study contributes the need towards the assessment of a wide range of environmental impacts for the pyrolysis process of different types of bio-wastes under different operating conditions. The study estimates the potential environmental impacts related to bio-char production from the pyrolysis of several different agro-industrial residues and different temperatures and identifies the process “hot spots”. The anal…
Internal shocks in relativistic outflows: collisions of magnetized shells
2007
(Abridged): We study the collision of magnetized irregularities (shells) in relativistic outflows in order to explain the origin of the generic phenomenology observed in the non-thermal emission of both blazars and gamma-ray bursts. We focus on the influence of the magnetic field on the collision dynamics, and we further investigate how the properties of the observed radiation depend on the strength of the initial magnetic field and on the initial internal energy density of the flow. The collisions of magnetized shells and the radiation resulting from these collisions are calculated using the 1D relativistic magnetohydrodynamics code MRGENESIS. The interaction of the shells with the externa…
A single-atom heat engine
2015
Making a teeny tiny engine Steam locomotives, cars, and the drinking bird toy all convert heat into useful work as it cycles between two reservoirs at different temperatures. Usually, the working substance where the heat-work conversion occurs is a liquid or a gas, consisting of many molecules. Roβnagel et al. have made a working substance of a single calcium ion in a tapered ion trap. A laser-cooling beam plays the part of a cold reservoir for the calcium ion, and in turn, electric field noise acts as a hot reservoir. Science , this issue p. 325
Reduction of phonon thermal conductivity in nanowires and nanoribbons with dynamically rough surfaces and edges
2009
We present an analytical model and molecular-dynamics simulations of the phonon heat transport in nanowires and nanoribbons with anharmonic lattices and dynamically rough surfaces and edges. In agreement with recent experiments on heat transport in single-crystalline silicon nanowires with rough surfaces, our model and simulations predict finite and length-independent phonon thermal conductivity in such quasi–one-dimensional systems, in contrast to anomalous phonon thermal conductivity of corresponding momentum-conserving systems with atomically smooth surfaces, divergent with the system length. Within our model, the main cause of thermal conductivity reduction is the momentum-nonconserving…