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- Experiments show that the heat transferred to or from a substance depends on three factors—the change in the substance’s temperature, the mass of the substance, and certain physical properties related to the phase of the substance.
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How does temperature affect heat transfer?
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Factors Affecting the Rate of Heat Transfer Through Conduction. In addition to temperature and cross-sectional area, another factor affecting conduction is the thickness of the material through which the heat transfers. Heat transfer from the left side to the right side is accomplished by a series of molecular collisions.
- 1.7: Mechanisms of Heat Transfer - Physics LibreTexts
Figure 1.7.1: In a fireplace, heat transfer occurs by all...
- 1.5: Heat Transfer, Specific Heat, and Calorimetry
As we learned earlier in this chapter, heat transfer is the...
- 1.7: Mechanisms of Heat Transfer - Physics LibreTexts
- What Is Heat Transfer?
- The Three Types of Heat Transfer with Examples
- Conduction
- Convection
- Radiation
- More Heat Transfer – Chemical Bonds and Phase Transitions
- References
Heat transfer is the movement of heat due to a temperature difference between a system and its surroundings. The energy transfer is always from higher temperature to lower temperature, due to the second law of thermodynamics. The units of heat transfer are the joule (J), calorie (cal), and kilocalorie (kcal). The unit for the rate of heat transfer ...
The three types of heat transfer differ according to the nature of the medium that transmits heat: 1. Conduction requires contact. 2. Convection requires fluid flow. 3. Radiation does not require any medium. 1. Conductionis heat transfer directly between neighboring atoms or molecules. Usually, it is heat transfer through a solid. For example, the ...
Conduction requires that molecules touch each other, making it a slower process than convection or radiation. Atoms and molecules with a lot of energy have more kinetic energy and engage in more collisions with other matter. They are “hot.” When hot matter interacts with cold matter, some energy gets transferred during the collision. This drives co...
Convection is the movement of fluid molecules from higher temperature to lower temperature regions. Changing the temperature of a fluid affects its density, producing convection currents. If the volume of a fluid increases, than its density decreases and it becomes buoyant.
Radiation is the release of electromagnetic energy. Another name for thermal radiation is radiant heat. Unlike conduction or convection, radiation requires no medium for heat transfer. So, radiation occurs both within a medium (solid, liquid, gas) or through a vacuum.
While conduction, convection, and radiation are the three modes of heat transfer, other processes absorb and release heat. For example, atoms release energy when chemical bonds break and absorb energy in order to form bonds. Releasing energy is an exergonic process, while absorbing energy is an endergonic process. Sometimes the energy is light or s...
Faghri, Amir; Zhang, Yuwen; Howell, John (2010). Advanced Heat and Mass Transfer. Columbia, MO: Global Digital Press. ISBN 978-0-9842760-0-4.Geankoplis, Christie John (2003). Transport Processes and Separation Principles(4th ed.). Prentice Hall. ISBN 0-13-101367-X.Peng, Z.; Doroodchi, E.; Moghtaderi, B. (2020). “Heat transfer modelling in Discrete Element Method (DEM)-based simulations of thermal processes: Theory and model development”. Progress in Energy a...Welty, James R.; Wicks, Charles E.; Wilson, Robert Elliott (1976). Fundamentals of Momentum, Heat, and Mass Transfer(2nd ed.). New York: Wiley. ISBN 978-0-471-93354-0.Figure 1.7.1: In a fireplace, heat transfer occurs by all three methods: conduction, convection, and radiation. Radiation is responsible for most of the heat transferred into the room. Heat transfer also occurs through conduction into the room, but much slower.
As we learned earlier in this chapter, heat transfer is the movement of energy from one place or material to another as a result of a difference in temperature. Heat transfer is fundamental to such everyday activities as home heating and cooking, as well as many industrial processes.
There is no net heat transfer once the temperatures are equal because the amount of heat transferred from one object to the other is the same as the amount of heat returned. One of the major effects of heat transfer is temperature change: Heating increases the temperature while cooling decreases it.
Each method has unique and interesting characteristics, but all three have two things in common: there is a net transfer of heat solely because of a temperature difference, and the greater the temperature difference, the faster the heat transfer (Figure 1.19).
Factors Affecting the Rate of Heat Transfer Through Conduction. In addition to temperature and cross-sectional area, another factor affecting conduction is the thickness of the material through which the heat transfers. Heat transfer from the left side to the right side is accomplished by a series of molecular collisions.
