UV Sciences new UVS family of UV light-based water purification chambers represent a dramatic improvement in the energy efficiency of UV water treatment chambers. The patented design features incorporated into the UVS series of highly reflective treatment chambers use fundamental science to provide superior performance. Under a wide range of UV transmittances, these chambers deliver the desired UV dose to the product more efficiently and uniformly than any other chamber available today.

This efficiency increase is so large that it often invites skepticism as to whether it is possible to truly achieve such an increase. However, the UVS performance improvement over conventional stainless steel-chambered reactors and even those using some type of reflector to improve the efficiency is based on one of the most basic principles in physics - conservation of energy.

In order to deliver the most energy to a target from a fixed source of energy, one must eliminate energy losses to the highest extent possible. In a situation in which the target occupies a relatively small amount of the volume near the source of the energy, that energy must be contained in a volume within the vicinity of the target to ensure that the target has adequate opportunity to absorb the energy. If the energy is not contained, it will have much less opportunity to be absorbed by the target. With a small target and poor containment, most of the energy will be lost before it can interact with the target. Good performance requires that the reflector must enclose the volume as completely as possible. In a practical chamber, there will be openings in the enclosure (water inlets and outlets are one example), but the size of these should be minimized to achieve the best performance.

A small target also requires the designer to minimize any other absorbers within the volume, so that the energy is mostly deposited in the target rather than the other absorbers. This includes the reflector - it must absorb as little energy as possible to create a very efficient system. From a practical standpoint, this means that the reflector employed must have as high a reflectivity as possible, and that anything inside the chamber must be designed to absorb as little of the energy as possible.

When these design concepts are strictly followed, the performance improvement can be truly remarkable, as shown in Figure 1. The important thing to note with this graph is that the reflector must have both a high reflectivity and a high chamber coverage percentage. Both are necessary to achieve a high enough increase in performance to make the added complexity of such a chamber worthwhile from a cost perspective.

Figure 1 shows that a >10X improvement over conventional chambers can be realized even in practical systems. This is a large enough improvement to make implementation of such a chamber practical at almost any flow rate. Other companies manufacture treatment chambers employing reflectors, but these reflectors usually have a peak reflectance of approximately 90% and effective chamber coverage of about 80%. These parameters are not sufficient to create a significant performance advantage over conventional systems. Also, as can be seen from Figure 1, improving only one of these parameters will not substantially increase the performance of the chamber. This combination of the high reflectance and high chamber coverage forms the basis for our patent (US 7,511,281 and subsequent applications) covering this type of treatment chamber.

Figure 1. Intensity inside a treatment chamber as compared to that of conventional chambers and other chambers with reflectors. The relative intensity is plotted as a function of reflectance of the reflector for different percentages of chamber coverage.

Figure 1. illustrates the conditions in which the water or other medium in the chamber does not absorb a significant amount of UV. The UVS series of treatment chambers has additional design features which allow it to have a clear advantage over conventional treatment chambers at relatively low UV transmittances (low UVT). There is still an advantage to having a highly reflective chamber wall, even for low UVT liquids.

Figure 2 shows two chambers which are identical except for the fact that one has a highly reflective chamber wall and the other does not.

Figure 2. Intensity in an absorbing medium is higher and more uniform with a highly reflective wall than with an absorbing wall.

The overall intensity in the chamber is the sum of the incident light plus any reflected light off the walls. In Figure 2, the graphs assume that the light source is at the left hand side of the axis, and that the chamber wall is at a distance d away from the source. Only one reflection at the wall is shown in this case, but multiple reflections are possible. A wall with poor reflection as shown on the left in Figure 2, causes the intensity inside the chamber to vary significantly as a function of distance from the source. If the wall is very reflective, the overall intensity is higher and there is less of a drop in intensity from the source to the wall. This results in a higher and more uniform dose within the chamber. Even in liquids with lower UVT, a highly reflective chamber will improve both the dose rate and the dose uniformity that the product encounters. This concept is also covered in a pending patent application.

UVSI has greatly improved the performance of UV water treatment processes. For information on how UV light can help you with your water treatment processes please contact us.