IR Temperature Measurements to Determine Fin Effectiveness of Longitudinal Fins

Abstract

Fins are widely used in heat exchangers, for cooling of electronics,... A good fin performance indicator is important for the design. The concept fin effectiveness is a better performance indicator than fin efficiency, which is the commonly used parameter. The big disadvantage of fin efficiency is that the real performance of the fin is compared to an ideal non-existing fin of the same shape but with infinitely high thermal conductance. So fin efficiency is an idealization and has physically no meaning. This makes it difficult to compare the thermal performance of different fin forms. On the other hand, fin effectiveness has the advantage of measuring the heat transfer gain obtained by placement of the fin and gives an idea of its real performance. It gives the ratio of the heat transferred by the fin to the heat transferred from the surface covered by the fin’s base under the same thermal conditions, in the absence of the fin. Fin effectiveness makes it possible to compare the fin quality of different types of fins. This can be used to develop a decision system to choose a fin type in order to remove a certain amount of heat from a surface for a given free surface area. The objective of this paper is to identify the fin effectiveness as well as the variation of the local convective heat transfer coefficient. Therefore the heat fluxes through the fin model and the primary surface need to be known. It is very difficult to do accurate heat flux measurements. It is easier and more common to measure surface temperatures.