Fin Efficiency and Fin Resistance The general concept of fin efficiency and fin resistance was developed in Chapter 1. The geometry of the numerical simulation was as shown in Figure 1 in which the fluid flows parallel to the base wall.
Fin efficiency is calculated from following expression.
Fin efficiency. Heat Sink Convection with Fins Calculator. The fin temperature effectiveness or fin efficiency is defined as the ratio of the actual heat transfer rate through the fin base divided by the maximum possible heat transfer rate through the fin base which can be obtained if the entire fin is at base temperature ie its material thermal conductivity is infinite. AfinπDL πD2 4 From Eq129 the heat transfer to the fin is at x 0 yields qfin.
Table 1 shows the dimension and test conditions in the present numerical. Heat Transfer by Convection of a Heat Sink with Fins Calculator and Equations. This relation enables us to determine the heat transfer from a fin when its efficiency is known.
This is the ratio of the fin heat transfer rate to the heat transfer rate of the fin if the entire fin were at the base temperature in this equation is equal to the surface area of the fin. Fin efficiency is defined as the actual heat transferred by the fin divided by the heat transfer were the fin to be isothermal hypothetically the fin having infinite thermal conductivity. Typically the fin material has a high thermal conductivity.
Heat Transfer Design and Engineering. Fin efficiency for predicting the performance of the heat exchanger. To account for the effect of this decrease in temperature on heat transfer we define a fin efficiency as 336 where Afin is the total surface area of the fin.
The heat transfer between fin and fluid is similar to the cross flow heat exchanger. To improve the fin tube efficiency fins are usually added on the surface of the heat exchange tube to increase the outer surface area or inner surface area of the heat exchange tube to achieve the purpose of improving the fin tube efficiency. 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.
The efficiency of a fin is defined as the ratio of the actual heat transfer from the fin to that the heat that would be dissipated if whole surface of the fin is maintained at base temperature. However they are related to each other by 341 Therefore the fin effectiveness can be determined easily when the fin efficiency is known or vice versa. This ratio will always be smaller than one.
Fin efficiency is defined as the ratio of actual heat flow of the fin to that which would be obtained with a fin of constant temperature uniformly equal to the base surface temperature that is one with infinite thermal conductivity. Fin performance can also be characterized by fin efficiency. This ratio will always be smaller than one.
Such a heat exchange tube is called a fin tube. ηth qfin hAfinTbT TfTand Afin2AcAtip Square and Recatngular 135 AtiptW Fig. Comparison of exact solutions for heat transfer in extended surfaces of different geometries.
Equations are applicable for straight fins. The fin efficiency and fin effectiveness are related to the performance of the fin but they are different quantities. Fin efficiency Fin efficiency is the ratio of heat transfer from the actual fin to the heat transfer of an imaginary fin of the same geometry and same conditions but with an infinite conductivity In other words if the entire fin surface was in a temperature equal to that of the fin base.
Efficiency of fin ηfin. Accordingly we will only reiterate the major equations and concepts here. The fin efficiency is defined as the ratio of the heat transfer to the fin to the heat transfer to an ideal fin.
Fin efficiency Fin efficiency is the ratio of heat transfer from the actual fin to the heat transfer of an imaginary fin of the same geometry and same conditions but with an infinite conductivity In other words if the entire fin surface was in a temperature equal to that of the fin base. 16 η Q Q ideal 0 b hP T – T a d x hPb T b – T a ξ 0 1 θ ξ d ξ An approximate VIM expression for the efficiency is obtained with respect to Eq. The fin efficiency is defined as the ratio of the actual heat transfer from the fin surface to the surrounding fluid while the whole fin is kept at the same temperature.