Mechanisms of Heating and Heat Transfer in the Outer Solar Atmosphere

1977 ◽  
Vol 36 ◽  
pp. 223-254 ◽  
Author(s):  
M. Kuperus ◽  
C. Chiuderi
Keyword(s):  
Heat Transfer ◽  
Solar Wind ◽  
Energy Loss ◽  
Electromagnetic Radiation ◽  
Solar Atmosphere ◽  
Thermal Conduction ◽  
Interstellar Space ◽  
Outer Corona

The amount of heat required to maintain the chromosphere and corona can be found from an estimate of the losses. The two processes that transport energy from the corona into interstellar space are electromagnetic radiation and the solar wind. In the Inner corona thermal conduction constitutes the dominant means of energy loss, but convection by the solar wind gradually takes over in the outer corona.

A Discussion on the physics of the solar atmosphere - The energy and pressure balance in the corona

1976 ◽  
Vol 281 (1304) ◽  
pp. 331-337 ◽  
Keyword(s):  
Solar Wind ◽  
Energy Balance ◽  
Solar Corona ◽  
Power Loss ◽  
Thermal Conduction ◽  
Theoretical Models ◽  
Pressure Balance ◽  
Radiated Power ◽  
Mechanical Waves ◽  
Outer Corona

This paper reviews theoretical models for the solar corona based on energy and pressure calculations. Processes included in these calculations are: ( a ) heating of the outer corona by mechanical waves; ( b ) convective out-flow of gas giving rise to the solar wind; ( c ) thermal conduction; ( d ) radiated power loss. Possible observations to help answer some of the outstanding questions about the energy balance are suggested.

scholarly journals Combined Heat Transfer Mechanisms in the Porous Char Layer Formed from the Intumescent Coatings under Fire

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 200
Author(s):  
Lingyun Zhang ◽  
Yupeng Hu ◽  
Minghai Li
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Thermal Conduction ◽  
Total Heat ◽  
Surface Radiation ◽  
Total Heat Transfer ◽  
Char Layer ◽  
Competition Result ◽  
Transfer Mechanisms ◽  
Combined Heat Transfer

This study examines the combined heat transfer by thermal conduction, natural convection and surface radiation in the porous char layer that is formed from the intumescent coating under fire. The results show that some factors, such as the Rayleigh number, conductivity ratio, emissivity, radiation–conduction number, void fraction and heating mode have a certain effect on the total heat transfer. In addition, the natural convection of the air in the cavity always inhibits surface radiation among the solid walls and thermal conduction, and the character of the total heat transfer is the competition result of the three heat transfer mechanisms.

scholarly journals Coupled THM and Matrix Stability Modeling of Hydroshearing Stimulation in a Coupled Fracture-Matrix Hot Volcanic System

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Yong Xiao ◽  
Jianchun Guo ◽  
Hehua Wang ◽  
Lize Lu ◽  
John McLennan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conduction ◽  
Dominant Role ◽  
Injection Well ◽  
Time Step ◽  
Volcanic System ◽  
Induced Stress ◽  
The Matrix ◽  
Matrix Stability ◽  
The Stability

A coupled thermal-hydraulic-mechanical (THM) model is developed to simulate the combined effect of fracture fluid flow, heat transfer from the matrix to injected fluid, and shearing dilation behaviors in a coupled fracture-matrix hot volcanic reservoir system. Fluid flows in the fracture are calculated based on the cubic law. Heat transfer within the fracture involved is thermal conduction, thermal advection, and thermal dispersion; within the reservoir matrix, thermal conduction is the only mode of heat transfer. In view of the expansion of the fracture network, deformation and thermal-induced stress model are added to the matrix node’s in situ stress environment in each time step to analyze the stability of the matrix. A series of results from the coupled THM model, induced stress, and matrix stability indicate that thermal-induced aperture plays a dominant role near the injection well to enhance the conductivity of the fracture. Away from the injection well, the conductivity of the fracture is contributed by shear dilation. The induced stress has the maximum value at the injection point; the deformation-induced stress has large value with smaller affected range; on the contrary, thermal-induced stress has small value with larger affected range. Matrix stability simulation results indicate that the stability of the matrix nodes may be destroyed; this mechanism is helpful to create complex fracture networks.

Second Law and Energy Loss Analysis in a Turbulent Flow Through a Nozzle Type Duct

2005 ◽  
Author(s):  
S. R. Javadinejhad
Keyword(s):  
Heat Transfer ◽  
Energy Loss ◽  
Exchange Process ◽  
Dimensionless Number ◽  
Inlet Temperature ◽  
Primary Concern ◽  
Loss Analysis ◽  
Heat Exchanger Design ◽  
Heat Exchange Process ◽  
Pattern Forming

Amount of heat transfer is the primary concern in a heat exchanger design. The amount of energy that has been destroyed during the heat exchange process has been investigated by introducing a new dimensionless number. Analyises of simpler systems are often useful to understand more important features of complex pattern forming processes in various field of science and technology. The entropy generation have been studied by use of new dimensionless number . This number defined as the ratio of total energy loss to total heat transfer across the duct length. The temperature dependence on the viscosity is taken into consideration and results have been derived for various L/D ratio, nozzle angles and inlet temperature.

scholarly journals Design and Implementation of a Laboratory Equipment for Studying Heat Transfer by Conduction

2019 ◽  
Vol 11 (1) ◽  
pp. 153-156
Author(s):  
István Padrah ◽  
Judit Pásztor ◽  
Rudolf Farmos
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Conduction ◽  
Thermal Conduction ◽  
Transfer Mechanism ◽  
Measuring Instrument ◽  
Heat Transfer Mechanism ◽  
Laboratory Equipment ◽  
Insulating Materials ◽  
Design And Implementation

Abstract Thermal conduction is a heat transfer mechanism. It is present in our everyday lives. Studying thermal conductivity helps us better understand the phenomenon of heat conduction. The goal of this paper is to measure the thermal conductivity of various materials and compare results with the values provided by the manufacturers. To achieve this we assembled a measuring instrument and performed measurements on heat insulating materials.

scholarly journals Self-Similar Theory of Thermal Conduction and Application to the Solar Wind

2015 ◽  
Vol 114 (24) ◽  
Author(s):  
K. Horaites ◽  
S. Boldyrev ◽  
S. I. Krasheninnikov ◽  
C. Salem ◽  
S. D. Bale ◽  
...  
Keyword(s):  
Solar Wind ◽  
Thermal Conduction ◽  
Self Similar ◽  
Similar Theory

The Sun

2015 ◽  
Author(s):  
Joanna D. Haigh ◽  
Peter Cargill
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Atmosphere ◽  
Space Weather ◽  
Extreme Ultraviolet ◽  
The Sun ◽  
Base Level ◽  
Earth’S Climate ◽  
The Magnetic Field ◽  
Terrestrial Magnetic Field

This chapter discusses how there are four general factors that contribute to the Sun's potential role in variations in the Earth's climate. First, the fusion processes in the solar core determine the solar luminosity and hence the base level of radiation impinging on the Earth. Second, the presence of the solar magnetic field leads to radiation at ultraviolet (UV), extreme ultraviolet (EUV), and X-ray wavelengths which can affect certain layers of the atmosphere. Third, the variability of the magnetic field over a 22-year cycle leads to significant changes in the radiative output at some wavelengths. Finally, the interplanetary manifestation of the outer solar atmosphere (the solar wind) interacts with the terrestrial magnetic field, leading to effects commonly called space weather.

scholarly journals Numerical Investigation into the Development Performance of Gas Hydrate by Depressurization Based on Heat Transfer and Entropy Generation Analyses

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1212 ◽  
Author(s):  
Bo Li ◽  
Wen-Na Wei ◽  
Qing-Cui Wan ◽  
Kang Peng ◽  
Ling-Ling Chen
Keyword(s):  
Heat Transfer ◽  
Energy Loss ◽  
Entropy Production ◽  
Entropy Generation ◽  
Gas Hydrate ◽  
Methane Hydrate ◽  
Dynamic Properties ◽  
Entropy Production Rate ◽  
Entropy Flow ◽  
Hydrate Reservoir

The purpose of this study is to analyze the dynamic properties of gas hydrate development from a large hydrate simulator through numerical simulation. A mathematical model of heat transfer and entropy production of methane hydrate dissociation by depressurization has been established, and the change behaviors of various heat flows and entropy generations have been evaluated. Simulation results show that most of the heat supplied from outside is assimilated by methane hydrate. The energy loss caused by the fluid production is insignificant in comparison to the heat assimilation of the hydrate reservoir. The entropy generation of gas hydrate can be considered as the entropy flow from the ambient environment to the hydrate particles, and it is favorable from the perspective of efficient hydrate exploitation. On the contrary, the undesirable entropy generations of water, gas and quartz sand are induced by the irreversible heat conduction and thermal convection under notable temperature gradient in the deposit. Although lower production pressure will lead to larger entropy production of the whole system, the irreversible energy loss is always extremely limited when compared with the amount of thermal energy utilized by methane hydrate. The production pressure should be set as low as possible for the purpose of enhancing exploitation efficiency, as the entropy production rate is not sensitive to the energy recovery rate under depressurization.

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