scholarly journals Thermal dynamics and electronic temperature waves in layered correlated materials

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Giacomo Mazza ◽  
Marco Gandolfi ◽  
Massimo Capone ◽  
Francesco Banfi ◽  
Claudio Giannetti
Keyword(s):  
Heat Transfer ◽  
Wide Spectrum ◽  
Interaction Strength ◽  
Energy Propagation ◽  
Electronic Temperature ◽  
Thermal Dynamics ◽  
Strongly Correlated Materials ◽  
Temperature Waves ◽  
Electronic Heat ◽  
The Way

AbstractUnderstanding the mechanism of heat transfer in nanoscale devices remains one of the greatest intellectual challenges in the field of thermal dynamics, by far the most relevant under an applicative standpoint. When thermal dynamics is confined to the nanoscale, the characteristic timescales become ultrafast, engendering the failure of the common description of energy propagation and paving the way to unconventional phenomena such as wave-like temperature propagation. Here, we explore layered strongly correlated materials as a platform to identify and control unconventional electronic heat transfer phenomena. We demonstrate that these systems can be tailored to sustain a wide spectrum of electronic heat transport regimes, ranging from ballistic, to hydrodynamic all the way to diffusive. Within the hydrodynamic regime, wave-like temperature oscillations are predicted up to room temperature. The interaction strength can be exploited as a knob to control the dynamics of temperature waves as well as the onset of different thermal transport regimes.

scholarly journals Thermal dynamics and electronic temperature waves in layered correlated materials

2021 ◽  
Author(s):  
Giacomo Mazza ◽  
Marco Gandolfi ◽  
Massimo Capone ◽  
Francesco Banfi ◽  
Claudio Giannetti
Keyword(s):  
Heat Transfer ◽  
Wide Spectrum ◽  
Interaction Strength ◽  
Building Blocks ◽  
Electronic System ◽  
Electronic Temperature ◽  
Thermal Dynamics ◽  
Temperature Waves ◽  
Different Temperatures ◽  
The Way

Abstract We explore layered strongly correlated materials as a platform to identify and control unconventional heat transfer phenomena. We demonstrate that these systems can be tailored to sustain a wide spectrum of heat transport regimes, ranging from ballistic, to hydrodynamic all the way to diffusive. Within the hydrodynamic regime, wave-like temperature oscillations are predicted up to room temperature. Temperature waves have a purely electronic origin, stemming from the existence of two components in the electronic system, each one thermalized at different temperatures. The interaction strength can be exploited as a knob to control the dynamics of temperature waves as well as the onset of different thermal transport regimes. The present results pave the way to transition-metal oxide heterostructures as building blocks for nanodevices exploiting the wave-like nature of heat transfer on the picosecond time scale.

Applying the Representative Interactive Flamelet Model to Evaluate the Potential Effect of Wall Heat Transfer on Soot Emissions in a Small-Bore DI Diesel Engine

2001 ◽  
Author(s):  
Carl Hergart ◽  
Norbert Peters
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Wide Spectrum ◽  
Turbulent Flame ◽  
Combustion Process ◽  
Heat Losses ◽  
Wall Heat Transfer ◽  
Two Phase ◽  
Flamelet Model ◽  
Di Diesel Engine

Abstract Due to the wide spectrum of turbulent and chemical length- and time scales occurring in a HSDI diesel engine, capturing the correct physics and chemistry underlying combustion poses a tremendous modeling challenge. The processes related to the two-phase flow in a DI diesel engine add even more complexity to the total modeling effort. The Representative Interactive Flamelet (RIF) model has gained widespread attention owing to its ability of correctly describing ignition, combustion and pollutant formation phenomena. This is achieved by incorporating very detailed chemistry for the gas phase as well as the soot particle growth and oxidation, without imposing any significant computational penalty. The model, which is based on the laminar flamelet concept, treats a turbulent flame as an ensemble of thin, locally one-dimensional flame structures, whose chemistry is fast. A potential explanation for the significant underprediction of part load soot observed in previous studies applying the model is the neglect of wall heat losses in the flamelet chemistry model. By introducing an additional source term in the flamelet temperature equation, directly coupled to the wall heat transfer predicted by the CFD-code, flamelets exposed to walls are assigned heat losses of various magnitudes. Results using the model in three-dimensional simulations of the combustion process in a small-bore direct injection diesel engine indicate that the experimentally observed emissions of soot may have their origin in flame quenching at the relatively cold combustion chamber walls.

Investigation of Heat Transfer Performances of Nanofluids Flow through a Circular Minichannel Heat Sink for Cooling of Electronics

2013 ◽  
Vol 832 ◽  
pp. 166-171
Author(s):  
M.R. Sohel ◽  
Saidur Rahman ◽  
Mohd Faizul Mohd Sabri ◽  
M.M. Elias ◽  
S.S. Khaleduzzaman
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Base Fluid ◽  
Heat Transfer Performance ◽  
Volume Fraction ◽  
Transfer Performance ◽  
Block Dimension ◽  
Electronic Heat ◽  
Flow Through ◽  
Cooling Of Electronics

Nanofluid is the suspension of nanoparticle in a base fluid. In this paper, the heat transfer performances of the nanofluids flow through a circular shaped copper minichannel heat sink are discussed analytically. Al2O3-water, CuO-water, Cu-water and Ag-water nanofluids were used in this analysis to make comparative study of their thermal performances. The hydraulic diameter of the minichannel is 500 μm and total block dimension is 50mm× 50mm× 4mm. The analysis is done at different volume fractions of the nanoparticle ranging from 0.5 vol.% to 4 vol.%. The results showed that the heat transfer performance increases significantly by the increasing of volume fraction of nanoparticle. Ag-water nanofluid shows the highest performance compared to the other nanofluids. So, this nanofluid can be recommended as a coolant flow through a circular minichannel for cooling of electronic heat sink.

Research on Influencing Factors of Cooling Process on Inclining Aluminum Profile Wall

2013 ◽  
Vol 389 ◽  
pp. 188-193
Author(s):  
Hai Bo Yang ◽  
Wen He Li ◽  
Hui Wang
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Spray Distance ◽  
Cross Sectional ◽  
Narrow Side ◽  
Wall Zone ◽  
Cooling Design ◽  
Cooling Effects ◽  
Sectional Shape ◽  
The Way

For these Aluminum extrusion products which cross-sectional shape are complex and size diverse, we usually discuss the convective heat transfer on the structural units with a single own geometrical characteristic separately at first, then combine them into a specified profile and reach a systematic uniform cooling design, to achieve a uniform cooling at last. This paper discussed heat transfer at the inclined wall zone with a calculation method of finite element. The considered factors are the spray distance, the flow rate of cooling mediums, the angle of inclination and the way of placement, which influence cooling effects separately. The results show that spray distance has little impact on cooling effects with an optimum range of 60mm to 100mm. As increasing the angle of inclination and flow rate of the cooling medium, profile has a faster and more uneven cooling. In addition, the way of placing profile with its narrow side attached to roller offers a higher cooling rate.

Analysis of Heat Transfer Enhancement in Minichannel Heat Sinks With Turbulent Flow Using H2O–Al2O3 Nanofluids

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
T. L. Bergman
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Turbulent Flow ◽  
Heat Transfer Enhancement ◽  
Thermophysical Properties ◽  
Heat Sink ◽  
Heat Sinks ◽  
Transfer Enhancement ◽  
Electronic Heat ◽  
Limited Usefulness

Heat transfer enhancement associated with use of a nanofluid coolant is analyzed for small electronic heat sinks. The analysis is based on the ε-NTU heat exchanger methodology, and is used to examine enhancement associated with use of H2O–Al2O3 nanofluids in a heat sink experiencing turbulent flow. Predictive correlations are generated to ascertain the degree of enhancement based on the fluid’s thermophysical properties. The enhancement is quite small, suggesting the limited usefulness of nanofluids in this particular application.

scholarly journals Ways to heat hot water via the heat pipes

2018 ◽  
Vol 168 ◽  
pp. 09003
Author(s):  
Peter Hrabovský ◽  
Zuzana Kolková ◽  
Jozef Matušov ◽  
Patrik Nemec
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Nuclear Power ◽  
Heat Pipes ◽  
Hot Water ◽  
Temperature Range ◽  
Thermal Output ◽  
Actual Use ◽  
Mechanical Elements ◽  
The Way

The article deals various ways of heating hot water where heat is transferred by the basic phenomena of heat transfer theories, which take place on an innovative basis with the advantage of the absence of mechanical elements. The heat transfer in this case ensures a change in the phase-in phase of the working substance – the fluid – from which the thermal output and the efficiency of the device are derived. The devices described in this article work on the same principle of heat transfer. Each device is characterized by own construction and the principle of heat transfer. Heat pipes are classified according to the way of operation and the place of use. Subdivision of the heat pipe, in terms of its actual, use in the desired temperature range. At present, heating plants use cooling technologies (nuclear power, space stations, IT).

scholarly journals O dwóch znaczeniach i jednym wartościowaniu leksemu czystość (na tle niektórych wyrazów pokrewnych i antonimów)

2015 ◽  
Vol 47 ◽  
pp. 99-124
Author(s):  
Beata Raszewska-Żurek
Keyword(s):  
Physical Meaning ◽  
Wide Spectrum ◽  
Human Life ◽  
Cultural Changes ◽  
Language History ◽  
Xvith Century ◽  
Wide Range ◽  
Positive Meaning ◽  
Polish Language ◽  
The Way

On the double meaning and single evaluation of the Polish lexeme czystość as compared with selected synonyms and antonyms This article is dedicated to evolution of both meanings of lexeme czystość – physical, meaning cleanness and ethical meaning purity with its’ evaluation. Both of them orginate from Praslavic language. For better understanding of its’ meanings adjective czysty, antonyms nieczystość, nieczysty, brud and brudny were taken into analysis.Ethical meaning of czystość as morality, righteousness was used commonly in Praslavic language and widely documented during the XVIth Century. It described wide range of positive meanings including sexual purity which became a dominant one. Despite of that fact czystość had great value and was described by positive epithets. It resulted from religious terminology and was one of the importancies in human life. Positive valuing of czystość in ethical meaning (purity) has not changed during next centuries but the way of expressing it has. Czystość described commonly known virtues like czystość serca, czystość zamiarów, czystość intencji, czystość obyczajów. Wide spectrum of understanding it as a virtue resulted in describing other accepted and positive values. Nowadays czystość as a virtue is used less common probably because of it’s pathetic overtone. Throughout the polish language history positive evaluation of purity was strongly underlined by its’ antonyms like nieczystość and transforming into ethical meaning brud.Physical meaning of czystość, rarely recorded because of the saced character of first documents (dominant ones) has not changed over the centuries. Nowadays this meaning become dominant. It resultes from cultural changes and orientation on hygienic style of life – physical czystość (hygiene) is connected with comfort, wellness and health. Unchengable positive meaning of physical czystość resultes from it’s strong antonym brud (dirt) which highly evokes sickness and repulsion.

scholarly journals Heat Transfer Modeling in Bone Tumour Hyperthermia Induced by Hydroxyapatite Magnetic Thermo-Seeds

2020 ◽  
Vol 14 (1) ◽  
pp. 77-89
Author(s):  
Fabio Fanari ◽  
Lorena Mariani ◽  
Francesco Desogus
Keyword(s):  
Heat Transfer ◽  
Numerical Models ◽  
Bone Tumour ◽  
Heat Transfer Process ◽  
Thermal Treatments ◽  
Hyperthermia Treatment ◽  
Theoretical Frameworks ◽  
Thermal Dynamics ◽  
Electromagnetic Power ◽  
Proposed Model

Background: Hyperthermia is an adjuvant oncologic thermal therapy. In the case of deep-seated bone cancers, the interstitial hyperthermia treatment can be performed using thermo-seeds, implanted biomaterial components that are able to convert external electromagnetic power into thermal one. Several magnetic biomaterials have been synthesized for thermal treatments of cancer. However, less attention has been paid to the modeling description of the therapy, especially when the bio-heat transfer process is coupled to the electromagnetic heating. Objective: In this work, a comparison between the available analytical and numerical models is presented. Methods: A non-linear multiphysics model is used to study and describe the performance of cylindrical magnetic hydroxyapatite thermo-seeds to treat residual cancer cells of bone tumours. Results: The thermal dynamics and treatment outcome are carefully evaluated. Under the exposure of a magnetic field of 30 mT, working at 300 kHz, it was found that magnetic hydroxyapatite implants with a size of 10 mm × 10 mm could increase the temperature above 42 °C for 60 min. Conclusion: The proposed model overcomes the limitations of the available theoretical frameworks, and the results reveal the relevancy of the implant geometry to the effectiveness of the hyperthermia treatment.

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