Search results for "exchanger"
showing 10 items of 101 documents
Conjugate heat transfer analysis within in lattice-filled heat exchanger for additive manufacturing
2020
Compact heat exchangers for heat removal has become one of the most effective cooling techniques. In this paper, numerical scheme to simulate conjugated heat transfer using additively manufactured ...
Effect of Heat Exchange Transient Conditions with Moving Water-Air Interface on Space Charge Accumulation in Undersea HVdc Cables
2021
The accumulation of space charge inside the dielectric layer of an HVdc cable is one of the most important issue to be considered in the design stage and during the operating conditions. The separation of space charge is due to several factors including the dependence on temperature of the electrical conductivity of the insulation and the establishment of a thermal gradient under load conditions. This article is focused on the investigation of the effect of an axial heat transmission on the space charge and electric field distributions in an HVdc cable. In order to assess the impact of this phenomenon, a case study involving a cable immersed partly in water and partly in air has been simula…
Temperature measurements along a vertical borehole heat exchanger: A method comparison
2019
Abstract The standard thermal response tests (TRT) provide integral and effective thermal parameters of the ground in the vicinity of borehole heat exchangers (BHE). However, typical ground properties are heterogeneously distributed. As a result, advanced TRT such as distributed and enhanced TRT are growing in popularity as they provide more spatial information of the thermal properties. Thus, the objective of this study is to compare various instruments to measure the depth-dependent temperatures using standard Pt100-sensors, fiber optical thermometers and novel instruments such as Geowire, Geoball and GEOsniff®. The investigations are carried out in a 30 m length test borehole. The result…
Sample building orientation effect on porosity and mechanical properties in Selective Laser Melting of Ti6Al4V titanium alloy
2022
Abstract In recent decades, the focus of research has shifted towards new production technologies with the aim of optimizing production and reducing costs. These innovative technologies include additive manufacturing processes as Selective Laser Melting (SLM). The analysis of the literature on the identification of optimal building orientation to maximize the mechanical properties and minimize porosity of the final products highlights contrasting results, denoting that the thermomechanical complexity of the process, as associated with the variation of the building orientation, has not been fully clarified. A study in which the building orientation effect was evaluated together with the geom…
An interactive multi-objective approach to heat exchanger network synthesis
2010
In this work we present a multi-objective approach to heat exchanger network synthesis. The approach solves a modified version of the Synheat model using an interactive multi-objective optimisation method, NIMBUS, which is implemented in GAMS. The results obtained demonstrate the potential of interactive multi-objective optimisation.
Ground Coupled Heat Pumps in Mixed Climate Areas: Design, Characterization and Optimization
2010
This contribution reviews the research work developed by the authors on the design, characterization and optimization of ground coupled heat pumps in mixed climates areas. The design of a ground coupled heat pump HVAC system starts with the estimation of the thermal loads that the air-conditioned area demands. The capacity of the ground source airconditioning system is determined from this thermal load estimation. With this value and a proper estimation of the ground thermal properties, the characteristics of the water to water heat pump and the required length and layout of the borehole heat exchangers are estimated. Determining ground thermal properties is crucial for an accurate design o…
Sodium dynamics: another key to astroglial excitability?
2012
Astroglial excitability is largely mediated by fluctuations in intracellular ion concentrations. In addition to generally acknowledged Ca 2+ excitability of astroglia, recent studies have demonstrated that neuronal activity triggers transient increases in the cytosolic Na + concentration ([Na + ] i ) in perisynaptic astrocytes. These [Na + ] i transients are controlled by multiple Na + -permeable channels and Na + -dependent transporters; spatiotemporally organized [Na + ] i dynamics in turn regulate diverse astroglial homeostatic responses such as metabolic/signaling utilization of lactate and glutamate, transmembrane transport of neurotransmitters and K + buffering. In particular, near-me…
Sodium Fluxes and Astroglial Function
2012
Astrocytes exhibit their excitability based on variations in cytosolic Ca(2+) levels, which leads to variety of signalling events. Only recently, however, intracellular fluctuations of more abundant cation Na(+) are brought in the limelight of glial signalling. Indeed, astrocytes possess several plasmalemmal molecular entities that allow rapid transport of Na(+) across the plasma membrane: (1) ionotropic receptors, (2) canonical transient receptor potential cation channels, (3) neurotransmitter transporters and (4) sodium-calcium exchanger. Concerted action of these molecules in controlling cytosolic Na(+) may complement Ca(2+) signalling to provide basis for complex bidirectional astrocyte…
Effects of ouabain on human bronchial muscle in vitro
2003
The effects of ouabain, an inhibitor of the plasmalemmal Na(+)/K(+)-ATPase activity, were examined in human isolated bronchus. Ouabain produced concentration-dependent contraction with -logEC(50)=7.16+/-0.11 and maximal effect of 67+/-4% of the response to acetylcholine (1 mM). Ouabain (10 microM)-induced contraction was epithelium-independent and was not depressed by inhibitors of cyclooxygenase and lipoxygenase, antagonists of muscarinic, histamine H(1)-receptors and alpha-adrenoceptors, or neuronal Na(+) channel blockade. The inhibition of ouabain contraction in tissues bathed in K(+)-free medium, and the inhibition by ouabain of the K(+)-induced relaxation confirm that the contractile a…
Preliminary Thermo-Mechanical Design of the Once Through Steam Generator and Molten Salt Intermediate Heat Exchanger for EU DEMO
2020
The European DEMOnstration power plant (DEMO) is considered to be the nearest-term fusion reactor capable of producing several hundred MWs of net electricity, operating with a closed tritium fuel-cycle (achieving the tritium self-sufficiency), and qualifing technological solutions for a fusion power plant with different breeding blanket (BB) concepts that are under investigation. The BB is a key component for the development of the DEMO plant design and, in particular, of those systems having the responsibility to remove the plasma-generated thermal power and its conversion in the electrical energy. This study deals with the preliminary thermo-mechanical design of the heat exchangers and st…