Related Concept Videos
01:19Mechanism of heat transfer
Understanding heat transfer mechanisms is essential for understanding how our bodies maintain balance in different environmental conditions. When the environment is thermoneutral, the body is in a state of balance, neither using nor releasing energy to maintain its core temperature. However, when the environment is not thermoneutral, the body employs four heat transfer mechanisms to maintain homeostasis: conduction, convection, evaporation, and radiation. These mechanisms facilitate heat...
01:14Mechanisms of Heat Transfer
Heat transfer between the human body and its environment occurs through four main mechanisms: conduction, convection, radiation, and evaporation.
Conduction, accounting for approximately 3% of body heat loss at rest, is the process of exchanging heat between molecules of two materials in direct contact. This can result in both heat loss and gain. For instance, when the body is submerged in water, which conducts heat 20 times more effectively than air, it can either lose or gain significant heat.
Conduction, accounting for approximately 3% of body heat loss at rest, is the process of exchanging heat between molecules of two materials in direct contact. This can result in both heat loss and gain. For instance, when the body is submerged in water, which conducts heat 20 times more effectively than air, it can either lose or gain significant heat.
01:14Mechanisms of Heat Transfer I
Just as interesting as the effects of heat transfer on a system are the methods by which the heat transfer occur. Whenever there is a temperature difference, heat transfer occurs. It may occur rapidly, such as through a cooking pan, or slowly, such as through the walls of a picnic ice box. So many processes involve heat transfer that it is hard to imagine a situation where no heat transfer occurs. Yet, every heat transfer takes place by only three methods: conduction, convection, and radiation.
01:20Mechanisms of Heat Transfer II
In convection, thermal energy is carried by the large-scale flow of matter. Ocean currents and large-scale atmospheric circulation, which result from the buoyancy of warm air and water, transfer hot air from the tropics toward the poles and cold air from the poles toward the tropics. The Earth’s rotation interacts with those flows, causing the observed eastward flow of air in the temperate zones. Convection dominates heat transfer by air, and the amount of available space for the airflow...
01:21Joule-Thomson Effect
The Joule-Thomson effect, also known as the Joule-Kelvin effect, describes the temperature change of a fluid when it is forced through a valve or porous plug while keeping it in a thermally insulated environment. This experiment is called a throttling process. This is an important effect widely used in refrigeration and the liquefaction of gases.
This experiment forces high-pressure gas through a throttle valve or a porous plug to a lower-pressure region. The gas expands as it passes through to...
This experiment forces high-pressure gas through a throttle valve or a porous plug to a lower-pressure region. The gas expands as it passes through to...
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Updated: May 18, 2026
05:20
Characterization of Thermal Transport in One-dimensional Solid Materials
Published on: January 26, 2014
Thermal transport in functionalized graphene.
Jeong Yun Kim1, Joo-Hyoung Lee, Jeffrey C Grossman
1Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
ACS Nano
|September 15, 2012
Summary
Patterning graphene with 2D shapes significantly reduces thermal conductivity by up to 40 times. This method tunes graphene
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Graphene's exceptional thermal conductivity makes it promising for thermal management.
- Controlling thermal transport in graphene is crucial for advanced applications.
- Existing methods often introduce defects, limiting performance.
Purpose of the Study:
- To investigate the impact of two-dimensional (2D) periodic patterns on graphene's thermal conductivity.
- To explore the mechanisms behind thermal transport modulation in patterned graphene.
- To assess the potential of patterned graphene for thermoelectric devices.
Main Methods:
- Employing molecular dynamics (MD) and lattice dynamics (LD) simulations.
- Analyzing the effects of boundary and clamping effects in patterned graphene.
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Main Results:
- Patterned graphene exhibits a significant reduction in thermal conductivity, up to 40 times lower than pristine graphene.
- Reduced phonon lifetimes due to scattering and direction-dependent group velocities from phonon confinement are key factors.
- The observed effects are attributed to boundary and clamping effects introduced by the 2D patterns.
Conclusions:
- Periodic 2D patterning offers a defect-free method to tune graphene's thermal conductivity.
- Patterned graphene nanoroads show potential for thermoelectric applications.
- This approach provides a pathway for designing materials with tailored thermal properties.