What is thermal penetration depth?
Thermal penetration depth is defined as the distance that heat can diffuse though the gas during a time 1/ω. In air oscillating at 1000 Hz, the thermal penetration depth is about 0.1 mm.
How do you calculate heat penetration?
The thermal penetration depth of the irradiated zone can be calculated by dth = (Dτ)0.5 with D = κ/ρc being the thermal diffusivity, κ the thermal conductivity, ρ the density, c the specific heat of the material (Table 1.1), and τ the pulse duration (6 ns).
What is the significance of Biot number?
The numerical value of Biot Number (Bi) is a criterion which gives a direct indication of the relative importance of conduction and convection in determining the temperature history of a body being heated or cooled by convection at its surface.
How can fin efficiency be improved?
Since the fin efficiency is inversely proportional to Λ, it can be improved either by increasing k and B, or by decreasing 〈h〉 and L. If the average heat transfer coefficient, 〈h〉, is increased due to an increase in the air velocity past the fin, the fin efficiency decreases.
What is FH value in tunnel?
: – Fh Value= ∆t X 10 (T- Tb)/Z Where, ∆t = Total time required for cycle i.e. 90 min. T = Average of each Probe temperature. Tb = Standard temperature for cycle. Z= Death Value i.e. 46.40C for Dry heat Sterilization. =90 X 10 (180.95-180)/46.4.
What is FH in sterilization?
Here, we’ll talk about the Fh value calculator which is in analogy with the above statement but for dry heat sterilization….Applications.
| Value | Application |
|---|---|
| F0 value | Moist Heat Sterilization/Steam Sterilization |
| Fh value | Dry Heat Sterilization |
| Fd value | De-pyrogenation (discussed further…) |
What is difference between Biot number and Fourier number?
Fourier number is a measure of heat conducted through a body relative to heat stored. The Biot number is the ratio of the internal resistance of a body to heat conduction to its external resistance to heat convection.
What is LC in heat transfer?
Lc [m] is the characteristic length of a material, h [W/(m² * K)] is the heat transfer coefficient at the material’s surface, k [W/(m * K)] is the thermal conductivity of the material.
What is difference between fin efficiency and fin effectiveness?
Therefore, the fin effectiveness can be determined easily when the fin efficiency is known, or vice versa. The overall effectiveness is a better measure of the performance of a finned surface than the effectiveness of the individual fins.
What is difference between F0 and FH?
And therefore, the F0 value is called Equivalent Exposure Time….Difference Between F0 and Fh Value.
| F0 Value | Fh Value |
|---|---|
| Much more complicated due to steam quality requirements | The lethality of the microbes is less than that of F0 at the same temperature |
What is D value Slideshare?
D-value refers to decimal reduction time and is the time required at a given temperature to kill 90% of the exposed microorganisms or to reduce the population by 1 log reduction.
What is meant by thermal penetration depth in physics?
The penetration depth is the depth to which the temperature has significantly changed, often, this is approximated with $$\\sqrt{\\pi a t}$$ where $a$ is the thermal diffusivity coefficient, and $t$ is time.
How is the penetration depth of a material determined?
Depending on the nature of the material, the electromagnetic field might travel very far into the material, or may die out very quickly. For a given material, penetration depth will generally be a function of wavelength.
Is the penetration depth of a material a function of wavelength?
For a given material, penetration depth will generally be a function of wavelength . According to Beer-Lambert law, the intensity of an electromagnetic wave inside a material falls off exponentially from the surface as Penetration depth is one term that describes the decay of electromagnetic waves inside of a material.
Which is the Biot number for thermal penetration depth?
Integration of Eq. (108) yields the Biot number NBi,δ ( t ), from which one finds the excess temperature at any depth x ≤ δth: The heat absorbed by the semi-infinite body is, for a given thermal penetration depth NBi,δ ,