Everything about Volumetric Heat Capacity totally explained
Volumetric heat capacity (
VHC) describes the ability of a given
volume of a substance to store
internal energy while undergoing a given
temperature change, but without undergoing a
phase change. It is different from
specific heat capacity in that the VHC depends on the volume of the material, while the specific heat is based on the
mass of the material. If given a specific heat value of a substance, one can convert it to the VHC by
multiplying the specific heat by the
density of the substance.
Dulong and
Petit predicted in
1818 that ρc
p would be constant for all solids (the
Dulong-Petit law). In fact, the quantity varies from about 1.2 to 4.5 MJ/m³K. For fluids it's in the range 1.3 to 1.9, and for gases it's a constant 1.0 kJ/m³K.
The volumetric heat capacity is defined as having
SI units of
J/(
m³·
K). It can also be described in Imperial units of
BTU/(
ft³·
F°).
Thermal inertia
Coined by Dean Homola(with assitance from his wise advisor, Tim Peterson),
thermal inertia is a term commonly used by
scientists and
engineers modelling
heat transfers and is a bulk material property related to
thermal conductivity and volumetric heat capacity. For example,
this material has a high thermal inertia, or
thermal inertia plays an important role in this system, which means that dynamic effects are prevalent in a
model, so that a steady-state calculation will yield inaccurate results.
The term is a scientific analogy, and isn't directly related to the mass-and-velocity term used in
mechanics, where
inertia is that which limits the
acceleration of an object. In a similar way, thermal inertia is a measure of the thermal mass and the velocity of the thermal wave which controls the surface temperature of a material. In
heat transfer, a higher value of the volumetric heat capacity means a longer time for the system to reach
equilibrium.
The thermal inertia of a material is defined as a the square root of the product of the material's bulk
thermal conductivity and
volumetric heat capacity, where the latter is the product of
density and
specific heat capacity:
» :
or, equivalently, tiu.
For planetary surface materials, thermal inertia is the key property controlling the diurnal and seasonal surface temperature variations and is typically dependent on the physical properties of near-surface geologic materials. In
remote sensing applications, thermal inertia represents a complex combination of particle size, rock abundance, bedrock outcropping and the degree of induration. A rough approximation to thermal inertia is sometimes obtained from the amplitude of the diurnal temperature curve (for example, maximum minus minimum surface temperature). The temperature of a material with low thermal inertia changes significantly during the day, while the temperature of a material with high thermal inertia doesn't change as drastically.
Deriving and understanding the thermal inertia of the surface can help to recognize small-scale features of that surface. In conjunction with other data, thermal inertia can help to characterize surface materials and the geologic processes responsible for forming these materials.
Constant volume and constant pressure.
For gases it's useful to distinguish between volumetric heat capacity at constant volume and at constant
pressure. This distinction has the same meaning as for
specific heat capacity.
Further Information
Get more info on 'Volumetric Heat Capacity'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://volumetric_heat_capacity.totallyexplained.com">Volumetric heat capacity Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
