1. Finned ratio definition
Finned ratio refer to the expansion surface after the bare tube (base tube surface) in the installation of the fins.
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. 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 light pipe area
Ab=3.1416 0.025= x Ab 0.0785 M
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.