The story behind the technology.
The new Vaportec helically corrugated heat transfer tubing system lies at the heart of every Vaportec tubular heat exchanger.
This new technology is the result of 15 years development in heat exchanger manufacturing and these heat exchangers are available in a variety of materials such as copper, stainless steel and Titanium.

International patents in over 20 countries.
Enhanced heat transfer tubes, otherwise known as enhanced surface tubes characterized by changes in shape to effect improvements in heat transfer performance compared with orthodox heat exchanger tubes of circular cross section.
In this regard, enhanced heat transfer tubes are to be distinguished from extended surface tubes, in which heat transfer performance is improved by increasing the effective surface area available for the heat transfer duty.
This can be achieved by superimposing fins on the inside or outside surfaces, and by the use of additional sections inserted inside the tubes or grooves.

Tubes of both types have been known for many years. The heat transfer aspects of enhanced tube technology now appear to be sufficiently well understood for most practical requirements.
The main problem with regard to manufacture of such tubing is to devise satisfactory methods for making technically acceptable tubes at commercially acceptable prices.

These production problems have now been resolved with the patented Spirex tube manufacturing process.

Vaportec Ltd has developed extensive knowledge over the early six years during the research and development period, concentrating on the manufacture of Spirex tube and the design, build and installation of various working uses of heat transfer equipment.
This has provided substantial ‘in place’ ( before and after) data which provides the basis of our design and application criteria.
The inherent advantages of Spirex tube began with the formation of the spirals. The method increases the surface area over a shorter lineal length, and combined with the induced turbulence, culminates in an enormous increase in overall heat transfer coefficient.

Improvements over plain tubing include substantial increase in collapsing strength, reduction in size of heat exchangers and increased heat transfer coefficients.

FUNDAMENTAL TEMPERATURE TRANSFER CONSIDERATIONS.

In the case of single phase fluid in turbulent flow parallel to a plane surface from which it is rejecting heat, the rate at which heat flows is where the film or surface heattransfer coefficient (which is a function of both physical properties of the fluid and the geometry of the system) indicates how efficiently the surface transfers heat.
However high the mainstream velocity may be, the fluid very close to the solid surface moves slowly, and it is the ease or difficulty with which heat flows across this boundary layer that determines the value of individual heat transfer coefficient between fluid and the surface.

A velocity gradient exists across the boundary layer of the latter being in laminar flow.
Movement of fluid particles perpendicular to the surface in the laminar sublayer is negligible and the heat transfer here is essentially by conduction.
There is also a buffer layer in which, at different times and places, flow may be laminar or turbulent, with and average velocity and turbulence level lower than those in the main stream.

Heat flows relatively easily across the buffer layer aided by he movement of fluid particles into and out of the mainstream but this layer does contribute to the total heat
transfer resistance.

If the simplifying assumption could be made that there is a completely laminar boundary of thickness with heat flow by conduction only, followed by a sudden transition to the fully turbulent conditions of the mainstream then the heat transfer coefficient between fluid and surface will increase.

The spiraling effect of Spirex increases the turbulence significantly, producing through its unique shape the geometrical shear phenomenon credited with producing the vast improvements documented independently by the University of Auckland and others.

Spirex Tube Form

SPIREX perforated tube:

The dynamic properties encouraged by the helical form of SPIREX perforated tube offer new and effective alternatives in:

• Emission control
• Noise suppression
• Dryers and airators
• Mixing and separating