Search results for "Cold"
showing 10 items of 660 documents
PCM thermal storage design in buildings: Experimental studies and applications to solaria in cold climates
2017
Abstract As energy availability and demand often do not match, thermal energy storage plays a crucial role to take advantage of solar radiation in buildings: in particular, latent heat storage via phase-change material is particularly attractive due to its ability to provide high energy storage density. This paper analyzes the performance of a building-integrated thermal storage system to increase the energy performances of solaria in a cold climate. A wall opposing a highly glazed facade (south oriented) is used as thermal storage with phase change materials embedded in the wall. The study is based on both experimental and simulation studies. The concept considered is particularly suited t…
Thermodynamics, transport phenomena, and electrochemistry of external field-assisted nonthermal food technologies
2017
Interest in the development and adoption of nonthermal technologies is burgeoning within the food and bioprocess industry, the associated research community, and among the consumers. This is evident from not only the success of some innovative nonthermal technologies at industrial scale, but also from the increasing number of publications dealing with these topics, a growing demand for foods processed by nonthermal technologies and use of natural ingredients. A notable feature of the nonthermal technologies such as cold plasma, electrohydrodynamic processing, pulsed electric fields, and ultrasound is the involvement of external fields, either electric or sound. Therefore, it merits to study…
PCM Thermal Energy Storage in Buildings: Experimental Study and Applications
2015
Abstract The study aims at analyzing the performance of Phase Change Materials (PCMs) in residential housing for different climates. This paper presents the results of an experiment performed in the Concordia University Solar Simulator and Environmental Chamber research facility (SSEC, Montreal, Canada). PCM boards were embedded on the back wall of a test hut placedin the climatic chamber. Several experiments were performed to explore the potential for verification of the proposed analysis and to produce enough data to perform model calibrations. Results show a strong increase in the apparent thermal inertia of the room allowing for a reduction in daily temperature fluctuations in the test …
LNG cold energy use in agro-food industry: A case study in Sicily
2011
Abstract It is known how the complete gasification of liquefied natural gas (LNG) can return about 230 kWh/t of energy. Nevertheless out of fifty-one gasification plants in the world, only thirty-one of them are equipped with systems for the partial recovery of the available energy. At the moment most of these plants mainly produce electric energy; however the employment of the cold energy results very interesting, in fact, it can be recovered for agro-food transformation and conservation as well as for some loops in the cold chain. Cold energy at low temperatures requires high amounts of mechanical energy and it unavoidably increases as the required temperature diminishes. Cold energy reco…
Numerical studies of the melting process in the induction furnace with cold crucible
2008
PurposeAims to present recent activities in numerical modeling of cold crucible melting process.Design/methodology/approach3D numerical analysis was used for electromagnetic problem and 3D large eddy simulation (LES) method was applied for fluid flow modeling.FindingsThe comparative modeling shows, that higher H/D ratio of the melt is more efficient when total power consumption is considered, but this advantage is held back by higher heat losses through the crucible walls. Also, calculations reveal that lower frequencies, which are energetically less effective, provide better mixing of the melt.Originality/value3D electromagnetic model, which allows to take into account non‐symmetrical dist…
Advanced refrigerating plants based on transcritical cycles working with carbon dioxide for commercial refrigeration
2012
Supermarkets and hypermarkets require a huge amount of energy to maintain chilled and frozen food in product display cases and cold storage rooms and thermal comfort in the whole building. Systems exploited require very large refrigerant charges for operation and suffer significant leakages. The challenge for advanced systems, based on equipment which reduce TEWI, suggests the proposal of carbon dioxide: a natural working fluid. This paper deals with a feasibility study of a refrigerating system for a big hypermarket in Sicily based on a three-stage transcritical cycle working with carbon dioxide which is compared with an alternative system composed of two cycles operating as a binary refri…
A Testing Facility for Refrigerating Plants Equipment Working with New Fluids
2013
A test rig was built in the department of energy, in laboratory of refrigerating engineering for test runs with a lot of fluid and equipment of various kind for commercial refrigeration. The facility has been continuously improved during the past years and allows to perform experiments aiming to assess the performance characteristics both of conventional and new equipment for commercial refrigeration. In the test rig can be tested a lot of cooling loop filled with a secondary fluid for simulation of their behavior in industrial and commercial plants (e.g.: during exploitation in supermarket and hypermarket for refrigeration of foodstuffs in cold store, display cases and cabinets, etc.). The…
Phytoplankton communities of polar regions–Diversity depending on environmental conditions and chemical anthropopressure
2015
The polar regions (Arctic and Antarctic) constitute up to 14% of the biosphere and offer some of the coldest and most arid Earth's environments. Nevertheless several oxygenic phototrophs including some higher plants, mosses, lichens, various algal groups and cyanobacteria, survive that harsh climate and create the base of the trophic relationships in fragile ecosystems of polar environments. Ecosystems in polar regions are characterized by low primary productivity and slow growth rates, therefore they are more vulnerable to disturbance, than those in temperate regions. From this reason, chemical contaminants influencing the growth of photoautotrophic producers might induce serious disorders…
Recent Development in Analytical Methods for Identification of Off-Flavour Compounds
1983
The best resolution of individual off-flavour compounds is achieved by glass or quartz capillary gas chromatography. A special two-column system was used by which simultaneous instrumental detection and sniffing (odour desorption) of odorous compounds could be done. The measuring detectors were flame ionization (FID), electron capture (ECD), flame photometric (FPD) and a mass spectrometer (MS). Structural assignments of the odorous substances were done from MS data and verified by model compounds. Before the GC run the sample was collected at the head of the double column using a cold trap device. The sample for analysis was injected in liquid form or, more efficiently, thermally desorbed f…
Methane oxidation in a boreal climate in an experimental landfill cover composed from mechanically–biologically treated waste
2007
The present study evaluated microbial methane (CH4) oxidation in a boreally located outdoor landfill lysimeter (volume 112 m3, height 3.9 m) filled with mechanically-biologically treated waste (MBT residual) and containing a cover layer made from the same MBT residual. The calculations based on gas emission and pore gas measurements showed that, between April and October 2005, a significant proportion (96%) of the methane produced (23 l CH4 m(-2) d(-1)) in the lysimeter was oxidized. Methane was oxidized mainly at the depths of 35-75 cm, as indicated by the upward decrease both in the methane concentration and in the methane-to-carbon dioxide ratio in the pore gas. Lower methane oxidation (…