سه شنبه ۲۷ شهریور ۰۳ | ۱۷:۵۶ ۹ بازديد
wo mediums reach the same temperature.
Heat can be transferred in three different modes: conduction, convection, and radiation.
All modes of heat transfer require the existence of a temperature difference, and all modes
are from the high-temperature medium to a lower-temperature one.
Conduction Heat Transfer
Conduction is the transfer of energy from the more energetic particles of substance to the
adjacent less energetic ones as a result of interactions between the particles. Conduction
can take place in solids, liquids, or gases. In gases and liquids, conduction is due to the
collisions and diffusion of the molecules during their random motion. In solids, it is due
to the combination of vibrations of the molecules in a lattice and the energy transport by
free electrons. A cold canned drink in a warm room, for example, eventually warms up to
the room temperature as a result of heat transfer from the room to the drink through the
aluminum can by conduction.
The rate of heat conduction through a medium depends on the geometry of the medium,
its thickness, and the material of the medium, as well as the temperature difference across the
medium. We know that wrapping a hot water tank with glass wool (an insulating material)
reduces the rate of heat loss from the tank. The thicker the insulation, the smaller the heat
loss. We also know that a hot water tank loses heat at a higher rate when the temperature
of the room housing the tank is lowered. Further, the larger the tank, the larger the surface
area and thus the rate of heat loss.
Consider steady heat conduction thro
Heat can be transferred in three different modes: conduction, convection, and radiation.
All modes of heat transfer require the existence of a temperature difference, and all modes
are from the high-temperature medium to a lower-temperature one.
Conduction Heat Transfer
Conduction is the transfer of energy from the more energetic particles of substance to the
adjacent less energetic ones as a result of interactions between the particles. Conduction
can take place in solids, liquids, or gases. In gases and liquids, conduction is due to the
collisions and diffusion of the molecules during their random motion. In solids, it is due
to the combination of vibrations of the molecules in a lattice and the energy transport by
free electrons. A cold canned drink in a warm room, for example, eventually warms up to
the room temperature as a result of heat transfer from the room to the drink through the
aluminum can by conduction.
The rate of heat conduction through a medium depends on the geometry of the medium,
its thickness, and the material of the medium, as well as the temperature difference across the
medium. We know that wrapping a hot water tank with glass wool (an insulating material)
reduces the rate of heat loss from the tank. The thicker the insulation, the smaller the heat
loss. We also know that a hot water tank loses heat at a higher rate when the temperature
of the room housing the tank is lowered. Further, the larger the tank, the larger the surface
area and thus the rate of heat loss.
Consider steady heat conduction thro
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