The element represents a pipe with a helical wire turbulator. Using the models by Ponweiser, the pressure loss coefficient and Nusselt-number are calculated as follows: $$\zeta = \zeta_{pi} + \frac{l}{D}\cdot 0.0277 \cdot \text{Re}^{0.765}\cdot Z$$ where $\zeta_{pi}$ is the pressure loss coefficient based on the Pipe-element. The coefficients are defined as follows: $A = -0.0707 \cdot \log\frac{l}{l_{pi}} -0 .1898$ $B = 0.0497 \cdot \log\frac{l}{l_{pi}} + 0.4945$ $C = 0.113 \cdot \left( \frac{l}{l_{pi}}\right)^{-0.3302}$ $D = 0.9417 \cdot \left( \frac{l}{l_{pi}}\right)^2 - 0.4833 \cdot\frac{l}{l_{pi}} + 0.2921$ $Z =\frac{C \cdot \frac{l}{l_{pi}} + D}{\left(1 + A \cdot \left( \frac{l}{l_{pi}}\right)^2 + B \cdot \left( \frac{l}{l_{pi}}\right)^2\right)\cdot\left(1 - 0.416 \cdot \left( \frac{l}{l_{pi}}\right)^2 + 2.5 \cdot \left( \frac{l}{l_{pi}}\right)^4\right)}$ Here, $l=l_{pi}$ is assumed; hence, the winding covers the whole length of the pipe.
$$Nu=0.0277 \cdot Re^{0.765}\cdot Pr^{1/3} \cdot \left[0.5 + \frac{0.5}{1 + A \cdot\left(\frac{h}{D}\right)^2 + B\cdot\left(\frac{h}{D}\right)^4} \right] \cdot \left[1 + e^{0.78}\right]$$ $A=-0.4801$ and $B=0.2963$
Parameter | Symbol | Unit | Description |
Length | \(l\) | m | Length of the element |
Count | \(N\) | none | Number of parallel elements |
Winding Distance | \(h\) | m | Winding distance of the turbulator coil |
Wire Diameter | \(D\) | m | Diameter of the wire |