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The transport of heat through a porous medium in the presence of
exterior forces, generally produced by the Earth's gravitational
field and/or a pressure gradient, is called conduction when the
Darcean fluid is static (motionless), and convection when the
Darcean fluid is in motion. It is customary to use the term
convection also to describe the motion which arises from the
density differences due to temperature gradients within the Darcean
fluid. We think that because this last phenomenon is more general
it should be given a specific name; here we call it thermal flow.
In the sense of the above definitions, convection and thermal flow
are two distinct phenomena (they occur together, in underground
combustion for instance), and the convective motion which arises
when a Darcean l'luid is in contact with a source of heat is a
particular case of thermal flow. Thermal flow occurs naturally and
is important in many geophysical and industrial problems,
particularly in oil exploration, and in the petroleum, chemical and
nuclear industries (for instance, in the evaluation of capability
of heat-removal from a hypothetical accident in a nuclear reactor).
It can play a part in the transfer of heat from the deep interior
of the Earth to a shallow depth in the geothermal regions. However,
in the field of energy conversion little attention has yet been
paid to the insulating characteristics of the saturated porous
materials introduced in some enclosures (storage tanks) to decrease
the convective and radiative transfer of heat.
The transport of heat through a porous medium in the presence of
exterior forces, generally produced by the Earth's gravitational
field and/or a pressure gradient, is called conduction when the
Darcean fluid is static (motionless), and convection when the
Darcean fluid is in motion. It is customary to use the term
convection also to describe the motion which arises from the
density differences due to temperature gradients within the Darcean
fluid. We think that because this last phenomenon is more general
it should be given a specific name; here we call it thermal flow.
In the sense of the above definitions, convection and thermal flow
are two distinct phenomena (they occur together, in underground
combustion for instance), and the convective motion which arises
when a Darcean l'luid is in contact with a source of heat is a
particular case of thermal flow. Thermal flow occurs naturally and
is important in many geophysical and industrial problems,
particularly in oil exploration, and in the petroleum, chemical and
nuclear industries (for instance, in the evaluation of capability
of heat-removal from a hypothetical accident in a nuclear reactor).
It can play a part in the transfer of heat from the deep interior
of the Earth to a shallow depth in the geothermal regions. However,
in the field of energy conversion little attention has yet been
paid to the insulating characteristics of the saturated porous
materials introduced in some enclosures (storage tanks) to decrease
the convective and radiative transfer of heat.
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