Design of Turbulators
We can assist with the design data for the turbulators we produce on a case by case basis depending on the application, type of turbulators requested and the fluids involved.
Our regular customers are also provided data which they can use for doing their own design.
Customization
To a large degree we can customize our turbulators to meet your requirements.
To better understand the effect of turbulators on performance we have given illustrative examples with the detailed designs also attached.
Example 1 : Brine cooled Air cooler
Example 2 : Produced Water heater
Example 3 : Shell and Tube exchanger
Key elements of Good Turbulator design.
While we stand ready, and prefer to help our customers with design, we have
Tried to present an overview by presenting some graphical data.
To do this we have done the following:
Chosen a ¾” OD tube as it is very widely used.
For this tube OD, we prepared the following data:
The pressure drop and heat transfer of oil of 3 viscosities, 5CST,
15 CST and 25 CST travelling through the tubes at a flow rate of
1 to 6 feet per second. This data was prepared for the following
Turbulator cases:
No Turbulator.
Rigid turbulators RT2, RT4 & RT6. (Our standards for this tube size).
Flexible turbulators FTD1, FTD2 & FTD3 (Again our standard models)
Twisted tape turbulators. Since the possibilities here are infinite for the case of better comparing the two, we selected those twisted tape turbulators that gave with a 15 CST oil the same pressure drop at 3 FPS flow rate as the corresponding standard flexible turbulators. We must bear in mind though, that twisted tape turbulators thus selected have a very high twist ratio and are not commonly manufactured. However they were chosen for their value in comparison. Most commonly used twisted tape turbulators will have a lower performance and pressure drop.
This data is represented graphically in the following charts/graphs.
From the curves, we can arrive at the following observations:
- The rigid soldered turbulators overall give the best heat transfer and also the highest pressure drop. However as the viscosity goes up, the performance as compared to flexible turbulator goes up significantly. For example in the 5 cst case, RT6 is above FTD3, RT4 above FTD2 and RT2 above FTD1.However at 15 cst both RT6 and RT4 are above FTD 3 and RT2 is very close to FTD 3. In the case of 25 CST all the three rigid turbulators are all above the highest performing flexible turbulators.The pressure drop is also compared to performance much lower.
- The performance of the twisted tape (even though the twisting selected is high to match the pressure drop of corresponding flexible wireTurbulator) is generally lower than that of the flexible but not by much. However given that we will not have such a high degree of twisting in standard available twisted tape turbulators we can say that the flexible turbulators performs better.
- The pressure drop increase for the two wire type turbulators with increase in fluid velocity is more than linear. The increase in performance is less than linear. This tells us that after a point it is not worth trying to purchase performance with pressure drop.
- The performance as well as the pressure drop in the case of twisted tape turbulators are more linear. To get another angle on this performance we worked out the following table, where we have simply divided the heat transfer coefficient by the corresponding pressure drop to get the HTPD factor (Heat transfer coefficient per unit of pressure drop). We did this for the three oil viscosities for all the Turbulator models at all the studied flow rates. We have color coded the results so that it is easier to spot the best as well as the trend.
The following facts emerge:
- Across all Turbulator types the HTPD factor goes down as the velocity increases.
- Across all turbulator types the HTPD factor goes down as the winding density increases.
- Different Turbulator types give comparatively different results under different viscosity and flow conditions.
- We can conclude that the best Turbulator is case specific.
The following should be kept in mind:
- The data for rigid turbulators are for rigid soldered turbulators. If the same turbulators are not soldered they perform but not as well. This is due to the better contact and so better heat transfer due to soldering.
- Just as pressure drop is a cost we pay for performance so is the dollar cost of material and labour. The rigid soldered Turbulator while an extremely efficient Turbulator is expensive to make and install.
- Ease of cleaning and maintenance are also key factors in Turbulator choice.
- Since we make all types, we have nothing to loose in giving you the correct advice.