1. What is finned ratio?

Finned ratio definition: Finned ratio refer to the expansion surface after the bare tube (base tube surface) in the installation of the fins. The fin performance ratio is a measure used to determine the real amount of heat passing through a fin in comparison to the maximum heat that can pass through it. The maximum heat flow is influenced by various factors such as the dimensions and shape of the fin, the materials thermal conductivity, and the heat transfer coefficient on the fins side.

Fin tube structure parameter can be represented by "β", i.e.

β = (the total surface area of the fin tube) / (the surface area of the bare tube)

2. How to calculate finned ratio?

Finned ratio Calculation example:

A fin tube, CPG (25 x 2.5 / 50 / 4 / 1 - Fe/Fe), calculate the fin ratio

1 meters long fin number n= 1000 / 4 =250

Fin area 1 meters long

Af = 250 * PI [/4 (Df^2-Db^2) 2+ * Df * T] =0.775 m pi

1 meters length on the bare tube area, namely the tube area without fin 

Ao = π * Db * 1 * (P-T) /P = 3.1416 * 0.025 * 1 * 3/4=0.0589 M

1 meters length of the bare pipe area

Ab=3.1416 0.025= x Ab 0.0785 M

Finned ratio result

β= (Af+AO) (0.775 +0.0589) / 0.0785 = 10.62

Then it means finned tube heat transfer area is 10.62 times the size of the bare tube.

Finned ratio