10a-d shows that the fin efficiency
decreases monotonically
(for different thermal conductivity and at a constant heat transfer coefficient) with increasing thermogeo- metric parameter. Also, it shows the variation of fin efficiency with thermogeometric in longitudinal convecting fin with insu- lated tip.
What affects fin efficiency?
Factors affecting fin effectiveness
P.Kh.Ac should be greater than unity if the rate of heat transfer from the primary surface is to be improved. If the ratio of P and Ac is increased , the
effectiveness
of
fin
is improved. Use of
fin
will be more effective with materials of large thermal conductivities.
What is the effect of thermal conductivity on?
The thermal conductivity of the metals of most of the fluids
decreases with increasing temperature
, with water being a notable exception. Thermal conductivity of liquids decreases with increasing molar mass at given temperature.
What is the effect of conductive heat transfer coefficient h’on fin effectiveness?
The higher value of h causes the smaller efficiency and effectivity of the fin. Sahin and Demir, 2008 found that heat transfer coefficient (h) affect to the fin’s performance. This is because
the temperature distribution generated on the fin has a closer temperature with the fluid around the fin
[5].
How effectiveness of a fin can be increased?
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.
Why does thermal conductivity of water increase with temperature?
For water below 130C, as the temperature increases, water molecules exist as a cluster due to hydrogen bonds, so instead of each molecules being further apart,
collision velocity increases
. Thus, higher thermal conductivity.
Is a high thermal conductivity good?
In SI units, thermal conductivity is expressed in watts per meter kelvin whereas in imperial units it can be expressed in BTU per hour per foot Fahrenheit . Materials with
a higher thermal conductivity are good conductors of thermal energy
.
Can fin effectiveness be less than 1?
The fin efficiency will always be less than one
, as assuming the temperature throughout the fin is at the base temperature would increase the heat transfer rate. … This is the efficiency for an array of fins.
Under what conditions does the fin efficiency become 100 %?
Under what situations does the fin efficiency becomes 100%.
The heat transfer from the fin will be maximum. For
the cases of a constant cross-section of very long fins and fins with insulated tips
, the fin efficiency can be 100.
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 thermal conductivity k of the fin material should be as high as possible. The overall effectiveness is a better measure of the performance of a finned surface than the effectiveness of the individual fins.
Which one of the following is correct the effectiveness of fin will be maximum in an environment with?
The effectiveness of a fin will be maximum in an environment with.
Free convection
.
What is effectiveness of fin 1 point?
The effectiveness of a fin will be
maximum in an environment with free convection
. Explanation: The fin temperature is also known as the fin effectiveness. Thus it is defined as the ratio of the actual amount of the heat transfered to the to the divided base temperature in the serve.
How do you calculate fin effectiveness?
- The fin efficiency is defined as the ratio of the heat transfer to the fin to the heat transfer to an ideal fin. ηth =
- qfin. hAfin(Tb − T∞) , Tf = T∞,and Afin = 2Ac + Atip (Square and Recatngular ) 1.35.
- Atip = t × W. Fig. 2.4. Rectangular Fin. For cylindrical: Afin = πDL +
What is an ideal fin?
An ideal fin is
the one whose temperature is equal to temperature of the surface
. This is possible only if the thermal conductivity of fin material is infinitely high. The effectiveness of an actual fin material is always lower than an ideal fin.
Which material is ideal for making a fin?
Aluminum and copper
are one of the most frequently used materials for fin.
What makes a good fin heat transfer?
Typically, the fin material has
a high thermal conductivity
. The fin is exposed to a flowing fluid, which cools or heats it, with the high thermal conductivity allowing increased heat being conducted from the wall through the fin.
