The invention relates to an air disinfection device using ozone for viruses, fungi and bacteria provided with an ozone recombination unit, comprising a housing, a fan arranged in the housing for forcing air to pass through the housing, an ozone generator included in the housing and arranged in a separate box which is positioned across the path of the airflow, and the ozone generator is electrically driven by a supply unit connecting a high voltage to said ozone generator to excite corona discharge.

The removal of bacteria and viruses from air is a long known task and there are different ways for solving this task. One of the most efficient ways include the use of ozone which has a high sterilizing potential, but if sufficient amount of ozone is used for this purpose, the room to be sterilized in this way should be emptied and after the sterilization a thorough ventilation is required in the room and no one can enter for more than at least 30 minutes.

Such a device is published in EP 1 973 578 Bl wherein it is described when the device is used, the room is evacuated of personnel. In the device in addition to ozone UV light is used, and one can read there that "the UV light and ozone work alone and synergistically to destroy pathogens. Particularly, the ozone is able to reach non-reflected surfaces because of its gaseous nature."

The different types of air sterilizers are summarized in the description of the prior art portion of the publication US 2012/014 1322A1 mentioning a common problem of UV irradiation-based sterilizers according to which "none of the above-identified apparatuses appear to be configured to effectively monitor and maintain the UV source of the apparatus at substantially maximum output levels." This statement indicates that the UV sources must operate under maximum output level.

The limited lifetime of components of UV photocatalytic air purifier/sterilizer systems is mentioned as a problem is included in US 8 557188 B2. It lists limited-lifetime components (such as the UV light, UV light electronics, and catalytic portion) and suggests the packaging of such components together to form a single, hand held, unitized package, designed for easy insertion and removal into an air purifier. This is an escape solution of the problem because what is really needed is the use of a system in which the components have long lifetime and no replacement is required.

Finally, reference is made to the publication WO 97/034682 Al in which ozone is used for sterilization but for attaining the required effect, a long meandering airflow path was provided so that the air to be sterilized is exposed to ozone for a longer time. In the publication UV irradiation was used in addition to the exposure of the airflow to ozone. Because ozone cannot be left to escape from the apparatus when used in a room, the publication uses a catalytic converter in which charcoal or molybdenum disulfide catalysts recombine ozone to O ₂ . The drawback of such a system lies in that catalytic converters will soon get saturated during excess use, and require frequent replacement which is expensive and inconvenient, and when they are close to saturation ozone can enter the airspace of the room which is dangerous to the health of the persons in that space.

Especially in the recent period when the worldwide presence of COVID 19 virus causes high problems to the mankind the efficient and reliable removal of viruses, bacteria and germs from closed air spaces where people stay, mainly in hospital rooms, airplanes, cinemas, theaters, offices and normal living rooms is an acute task. The air disinfection should be solved with maximum efficiency, with high reliability of the operation that does not require frequent maintenance and replacement of any component, that prevents the entering of ozone or unwanted irradiation into the protected airspace and finally which operates with small energy consumption.

The main objective of the invention is to provide a device that can satisfy all of the listed requirements. Within this objective a second objective lies in providing an ozone recombination device that does not require any filter material that should be replaced time to time or any chemical entity for neutralizing ozone.

The solution of the main objective is based on a number of recognitions which can be summarized as follows. Previously the two known disinfection methods, namely UV-C irradiation and using ozone were used with the purpose of providing maximum power of UV-C light and maximum concentration of ozone instead of providing maximum sterilization efficiency. It has been realized that the simultaneous exposure of a pulsated UV-C light with a frequency higher than about 10 KHz and a pulsated generation of corona discharges in an ozone generator to an airflow can provide a maximum sterilization effect with minimum energy consumption. A further discovery lies in that the recombination of ozone can be provided by using a pulsated high electric field across the passage of airflow, wherein the frequency of the pulses is higher than about 10 KHz and the field strength is slightly under the threshold where corona discharge takes place. Such an ozone recombination device does no use any catalyst or material that would need replacement, has minimum energy consumption and is capable of removing ozone from the air stream, thus the ozone-based sterilization can be used in closed spaces with the presence of people.

For solving the above objectives and utilizing these recognitions an air disinfection device has been provided using ozone for killing bacteria and viruses together with an ozone recombination unit that is structured as defined in the attached claims.

According to the invention an ozone recombination unit has also been provided to be placed across the flow of ozone containing air for neutralizing ozone included in the air flow and the unit is built as defined in the attached independent claim 14.

The invention has perfectly solved the tasks set, and the simultaneous pulsated supply of UV light and ozone has an increased effect on bacteria and viruses present in the box and either kill them or make them unable to multiply.

The invention will now be described in connection with preferred embodiments thereof in which reference will be made to the accompanying drawings. In the drawing:

Fig. 1 shows he simplified schematic block diagram of a preferred embodiment of the device;

Fig. 2 shows a schematic sectional elevation view of the device;

Fig. 2a shows an enlarged front view of the mirror box;

Fig. 2b shows an enlarged detail of the recombination unit;

Fig. 2c shows a detail of the additional ozone filter;

Fig. 2d shows a detail of an additional UV filter;

Fig. 3 shows the simplified view of a second embodiment of the device;

Fig. 4 shows the sketch of the reaction chamber in perspective view;

Fig. 5 is a simplified cross section of the reaction chamber 130;

Fig. 6 shows the top view of the discs 131, 132 limiting the reaction chamber;

Fig. 7 is a sketch illustrating an embodiment of the heater 160; and

Fig. 8 shows the open end part of the cylinder and of the device. Reference is made now to figure 1 that shows the functional block diagram of the subject virus and bacteria killing device, that comprises a metal, preferably steel housing 10 in which all functional units are arranged and which also provides an electromagnetic shield around the functional units to prevent the environment from spurious electromagnetic noise. The housing 10 has a front plate 11 and a rear plate 12, and both are provided with a plurality of holes for providing passage for air to flow in and out from the housing 10.

Directly behind the front plate 11 a fan 20 is arranged which is the type that is driven by pulse width modulated (PWM) pulses, and its speed can be controlled by the frequency and on/off ratio of the pulses within a wide range. The mean frequency is around 25 kHz and the pulse voltage is 12 V. A separate first controlled PWM supply unit 21 is coupled to the fan 20 by which the airflow rate can be adjusted. The air is forced to flow between the front and rear walls 11, 12 of the housing 10 which is referred to as length direction or direction Z as shown in Fig. 2. The air flows substantially in a laminar stream. A special mirror box 30 is arranged in front of the fan 20 in which two separate functional units are arranged in an integrated way, namely an elongated UV lamp 40 extending centrally along the length of the mirror box 30 and six ozone generators 50a, 50b, 50c, 50d, 50e and 50f which are formed by respective tubes and they are arranged in equal angular spacing around the UV lamp 40 (see Fig 2a). In the exemplary embodiment the six ozone generators have the same design and also extend in the direction Z trough the mirror box 30.

The UV lamp 40 is a germicidal lamp of the UV-C type that emits UV light in and around the 254 nm range of wavelengths, and it is supplied also with PWM pulses of a second supply unit 41, wherein the frequency and the duty cycle of the pulses can be adjusted. The frequency is around 16 KHz and the peak voltage is around 100 V. It should be noted that the terminals of the heating filaments of the UV-C lamp are shorted, whereby the lamp functions in cold cathode mode. This kind of operation extend the life time of the UV_C lamp 40 in a significant extent, from a nominal expected life time of 100 hours to about 50.000 to 60.000 hours. The high frequency excitation allows the cold mode, and the energy consumption is also reduced to a significant extent. In a preferred embodiment the diameter of the UV-C lamp is 16 mm. The mirror box 30 has a front plate 31 and a similarly designed rear plate 32 that fit in the square interior thereof as shown in Fig. 2a. In the exemplary embodiment a central circular piece 33 is provided as inner part of the front plate 31 (and a similar one provided in the rear plate 32) that has a central opening which fits to the outer diameter of the UV lamp 40 and holds the same. The UV lamp 40 extends centrally along the longitudinal axis of the mirror box 30 and the respective ends extend out from the front and rear plates

31, 32, whereby there is place for the connection of its electrical contacts. A preferred diameter of the UV lamp 40 is 20 mm.

Both the front and rear plates 31, 32 of the mirror box 30 have respective ringshaped openings 34 around the central circular piece 33 which has radial size equal with the diameter of tubes of the ozone generators 52a, 52b, 52c, 52d, 52e and 52f which are positioned and held in even angular distribution in the ring-shaped opening 34. The body of the respective ozone generators is formed by the tubes with a diameter of 22mm and fixed at their both ends to the front and rear plates 31, 32 at their outer portions. The tubes of the ozone generators 52a to 52f are made preferably of special quartz glass transparent for UV-C light, and the mechanical connection can be provided by any known ways, wherein a preferred way is the use of an appropriate adhesive. The diameter of the tubes is preferably around 20mm. The ring-like opening 34 allows air driven by the fan 20 into the interior of the mirror box 30 in such a way that air flows between the tubes of the ozone generators 52a to 52f and through the inner passages within the respective tubes 52a to 52f and leave the interior over the similar ring like opening in the rear plate

32.

Around the outer surface of each tube that forms the respective ozone generators 52a to 52 f a helically arranged outer spiral winding is provided, and in a similar way in the interior surface of each tube a helically wound inner spiral winding is made. The outer and inner windings have the same pitch and arranged so to cover each other, i.e. between them only the wall thickness of the quartz tube defines the distance. In a preferred embodiment this distance is around 1.5 mm. There are several ways of arranging the windings which should resist the presence of ozone and the intensive UV-C light, and the best choice for the material of these windings can be a wire made of non- corrodible steel or a steel alloy. If the inner winding is wound to have a diameter slightly greater than the inner hole of the quartz tube, then by the squeezing of this winding it can be inserted in the tube and then the resilience of the winding will try to expand and press it to the inner wall which stabilizes the position. There are several ways of placing the outer winding on the outside of the tube that can be a similar press-connection but the use of an adhesive can also be a solution. The ends of the respective inner and outer windings constitute the lead out terminals of the respective ozone generators 50a to 50f, and they are connected in parallel and coupled to a further supply unit 51.

It has been explained that the six ozone generators 50a to 50f surround the centrally extending UV-C lamp 40 and this arrangement fills the whole interior of the mirror box 30. The inner surfaces of the plates or covers constituting the mirror box 40 are preferably covered by a light reflecting layer and act as mirrors, whereby the UV-C light radiation emitted by the lamp 40 will have numerous reflections and the light rays will illuminate the whole interior of the mirror box 30. The quartz glass surfaces of the six tubes 52a to 52f also reflect the incident light therefore the UV-C light will reach all parts of the interior of the mirror box 30.

The third PWM supply unit 51 generates high voltage pulses with an adjustable frequency around 40 KHz and the peak voltage is around 40 KV. The parameters of this pulsated voltage are chosen in such a way that a corona discharge is formed between the outer and inner windings of each ozone generator 50a to 50f, whereby the generated ozone will fill the interior of the mirror box 30.

Behind the mirror box 20 an ozone recombination unit 60 is arranged which has the task of forcing the O ₃ molecules present in the inflowing air to get recombined so that normal ozone-free air should leave the unit 60 and the housing 10. This ozone recombination unit 60 is supplied by a fourth PWM power supply 61 which generates pulses around 16 KHz and the pulse voltage is also around 40 kV.

The four different PWM supply units 21, 41, 51 and 61 are fed from a central power supply and control unit 70 which is a step down type converter that generates converted DSC output voltage of around 11V from a DC input supply of around 12V. The task of this power supply and control unit 70 is to prevent the passage of unwanted spurious signals outside the device and has an efficient spurious signal rejection property in a wide frequency range. A standard mains filter 71 provides further screening of unwanted signals. Behind the ozone recombination unit 60 optional filters 62 can be arranged that further enhance the recombination of ozone and can also prevent the passage of unwanted UV light out of the housing 10.

Fig. 2 shows substantially the same arrangement as in Fig. 1 however now the electronic units were not shown and the size of the different units in the drawing correspond more to the actual size of these units as positioned in the housing 10. In fact, Fig 2 is an elevation sectional view of the device. The fan 20 generates a forced airflow in the longitudinal direction Z in the interior of the housing 10, because both the front and rear plates 11, 12 are perforated and a plurality of openings allow the passage of air therethrough. The speed of the fan 20 can be adjusted between about 300 rpm and 1500 rpm (revolutions per minute) and the most frequently used range is between about 800 and 1200 rpm, whereby the flow rate varies between about 20 - 25 m ³ /h. The inflowing air might contain bacteria and viruses which should be killed or made inactive within the mirror box 30, and the air leaving the mirror box 30 is free of any living or active bacteria or virus.

The ozone recombination unit 60 comprises two nets formed of vertical and horizontal wires wound and arranged in different spaced planes. Fig. 2 has a distorted illustration in the sense that two separate windings i.e. outer winding 63 and inner winding 64 are wound on respective rectangular spaced frames 65, 66. There is a space between each adjacent wire in the windings so that air can flow through the windings. The plane of the windings is normal to the flow direction Z, and also normal to each other.

In Fig. 2b there is an enlarged detail of the ozone recombining unit 60, parts of the two spaced frames 65, 66 can be seen, which are made of a planar non-conductive material with rectangular shapes and have a large open interior. The spacing is around 3mm. The inner winding 64 is wound around the two frames in a horizontal direction and the cross section of the respective wires in Fig. 2b looks like little circles. At the outer part of the frames 65, 65 respective distance members are provided, and the outer winding 63 is wound in vertical direction around the outer part of the distance members, and in Fig. 2b a wire 67 of a part of a vertical loop (or turn) of the outer winding 63 is illustrated (in a distorted view). In this way in the airflow direction Z the air flows first through the front plane defined by the outer wires (that extend in vertical direction) of the outer winding 63, then crosses the horizontal front wires of the inner winding 64, wherein the spacing here is around 2.5 to 3mm, then proceeds through the spacing between the two frames 65, 66 which is around 3mm, and flows through the rear horizontal wires of the inner winding 64 and finally flows through the rear vertical wires of the outer winding 63 and proceeds towards the rear plate 12.

In this way the air proceeds twice between the air gaps formed between the outer and inner windings 63, 64 and it is exposed to the effect of the electromagnetic fields established between the two windings 63, 64 by the pulses of the fourth supply unit 61.

The electric field has opposite direction between the first two winding planes and the third and fourth winding planes at each moment. Because the wires of the oppositely located wires are extending normal to each other, the field strength will have a different shape compared to the field which prevailed in the ozone generators, wherein the wires with opposite polarity are extending parallel to each other. In contrast thereto the wires in the windings of the recombination unit 60 extend normal to each other and they are closest to each other at the virtual crossing points only. When the amplitude of the pulses switched between the two windings 63, 64 is below the value at which corona discharge take place, this specific filed will cause ozone molecules to recombine to oxygen.

Behind the ozone recombining unit 60 two different kinds of optional filters 62a and 62b can be arranged. The first comprises a pair of spaced metal plates 68, 69 extending normal to the airflow direction, and each of them has a high number of circular openings shown in the enlarged picture of Fig. 2c where the openings of the first plate 68 are drawn by full line and the ones in the second plate 69 are drawn by dotted lines. These openings have a diameter of around 3 to 4 mm and the openings in the two plates 68, 69 are offset relative to each other when seen from the flow direction Z, so that air cannot flow through the pair of the plates 68, 69 because their path will be broken and they have to have sudden changes in their flow direction by abutting to at least one of the two plates 68 or 69. This sudden change of flow direction further facilitates recombination of the rest of any ozone particle in the airflow past the recombination unit 60.

A further optional unit shown in Fig. 2 is a screening unit 62b for the UV light that has elongated rounded openings shown in the enlarged picture of Fig. 2d, and the role of this screening unit 62bis to prevent passage of UV light out of the housing 10. The light will not be able to pass through these openings past the previous units. The operation of the device according to the invention is as follows. The contaminated air that might contain bacteria and viruses enter the device through the holes of the front plate 11, and the fan 20 drives air in axial direction Z. The contaminated air enters the interior space of the mirror box 30. There when the germicidal UV C lamp 40 is driven by the supply unit 41 by the pulses of around 100 Volt and having a frequency around 16 KHz will light on and issues pulsating light rays in the UV-C range. These light pulses are lethal to bacteria and viruses. As known short-wave ultraviolet light disrupts DNA base pairing, causing formation of pyrimidine dimers, and leads to the inactivation of bacteria, viruses, and protozoa. The light will reach all parts of the interior of the mirror box 30 and the light-reflecting inner surface increases the intensity of the light in all parts of the interior. Because of the use of high frequency pulses the effects of the light on the viruses will be more intensive and a smaller light intensity will have the same destroying effect as what can be reached by a continuous light of much higher intensity.

In addition, when the six ozone generators 50a to 50f around the UV lamp 40 receive high frequency excitation, the pulsating electric field established under the effect of the above 40 kV voltage difference between opposite points of the outer and internal windings will generate corona discharge. Such discharges energize nitrogen oxide molecules, whereby nitrogen-monoxide and O ₃ (ozone) are generated accompanied by the appearance of a special blue light. Ozone is an aggressive gas that destroys the DNS of the living cells present. Such cells have been previously at least weakened or killed under the effect of the UV-C light. With destroyed DNS the virus and bacteria cells will be unable to multiply and function.

The simultaneous presence of ozone and UV-C light has a synergistic effect in the sense that much less ozone and a smaller intensity of UV light will be needed for attaining the same destroying effect as otherwise it would be necessary if only UV-C light or only ozone was used. The use of pulses further strengthens this effect.

By the time the air flows through the interior of the mirror box, all bacteria and viruses present will become inactivated or totally killed, therefore the air flowing out of the mirror box 30 will be clean of viruses and other contaminating germs.

The appearance of blue light as a side effect of the generation of ozone provides assistance in adjusting the voltage, frequency and pulse duty cycle. On the mirror box 30 one can provide a small inspection hole for sensing such a blue light, or a light sensor can be arranged in the box, and the parameters of the PWM supply unit 41 can be adjusted by watching the appearance of the blue light and adjusting these parameters to the level when such light appears and stays through a longer period.

Although the amount of ozone required for triggering the virus killing effects is not too high, safety rules prevent the leading of even small volume of ozone in rooms where persons can be present. The ozone recombination unit 60 shown in Fig. 8 has the task to facilitate the recombination of ozone to normal two atom oxygen gas before leaving the device.

The direction of the momentary electric field in the direction Z is always opposite in the first gap between the adjacent first planes of the outer and inner windings 63, 64 and in the next gap between the adjacent second planes of the inner and outer windings 64, 63. As the gas molecules move in the direction Z, they are exposed to such a pulsating and changing electric field that causes an intensive movement of the molecules that facilitates the recombination of the instable ozone again to two atom normal O ₂ molecules. This recombination effect depends on the voltage, frequency and duty cycle of the pulses coupled to the two windings 63, 64. Because the human smell is very sensitive to ozone, even the smallest concentration in the air leaving the device can be sensed. Therefore the parameters of the pulsated signal i.e. frequency, duty cycle and voltage can be finely adjusted so that in spite of substantial presence of ozone in the mirror box 30 ozone smell cannot be sensed in the out flowing air. As mentioned earlier, the best recombination data were obtained at a pulse voltage of 40 KV, and a frequency of around 16 kHz, and a duty cycle of around 70%.

The ozone recombination unit 60 can be realized in several different ways as shown in the preferred embodiment, because the recombination takes place under the effect of a pulsated voltage signal that generates sufficiently high field strength within the unit. The filter 62afurther increases the efficiency of the recombination process, while the UV filter 62b prevents UV Light from leaving the device.

While the ozone recombination unit 60 performs an excellent function by recombining ozone generated in the mirror box 30, the recombination of ozone can be utilized in a number of different ways. In summary, it can be said that the embodiment shown provides safe and efficient air disinfection with minimum amount of energy, as the synergistic effect of the simultaneous use of the UV C lamp 41 and the ozone generators around it require much less energy as if they were used as self standing air disinfection units.

Reference is made now to Figures 3 to 8 in which a further preferred embodiment of the air disinfection device 100 is shown. Fig. 3 shows the general layout of the device 100 which has a wide, flat disc-like base 110 that has a number of feet 111 at the bottom made of cylindrical or cup-like body made preferably of rubber that keeps a distance of around 15 mm from the support plane 101. A fan 112 is arranged in the base 110 which has a similar design as the fan 20 in the previous embodiment but has a higher airflow rate up to over 200 m ³ /hour, and it is also driven by pulse width modulated PWM pulses of variable frequency. The fan 112 has a vertical airflow direction and the central portion of the base 110 is open to allow air to flow upward under the driving effect of the fan 112. The bottom of the device is closed by a perforated plate 113 that allows air passage therethrough. The height of the base is around 40 mm. An upright cylinder 120 is attached from above to the central open part of the base 110, which has the task of holding the virus killing and ozone recombination parts of the device 100 and the air driven by the fan 112 flows through the cylinder 120. The cylinder has a preferred diameter of 100 mm. The base 110 and the cylinder 120 constitute together the housing of this second embodiment.

In the wide body of the base 110 outside the open central zone the power supply units and control elements of the device are arranged, and in this way they do not take away space and volume from the parts arranged in the cylinder 120. Most of the electronic control blocks (mainly the power supply units) of the device 100 are the same or similar to those shown in the previous embodiment, however, a few further blocks allow additional functions as will be explained later.

The major part of the interior of the cylinder 120 is constituted by a reaction chamber 130 which has the similar function as of the mirror box 30 in the previous embodiment. A simplified perspective view of the chamber 130 is separately illustrated in Fig. 4. The bottom and the top of the reaction chamber 130 are made by a pair of identical and spaced discs 131, 132 that hold four UV-C lamps 140, 141, 142 and 143 and five ozone generators 150, 151, 152, 153 and 154. The spacing is provided by four distance rods (not shown in the drawing) made of copper which also serve as connection wires for the units above the reaction chamber 130. The UV-C lamps can be similar to the lamp 40 in the first embodiment, the difference lies in that their length is greater, namely 140 mm in the preferred embodiment and they are arranged with respective vertical axes and when viewed from above their axes fall in the corners of an imaginary square, and their diameter is again 16 mm. The ozone generators 150 ... 154 have the same design as the ozone generators 50a to 50f in the first embodiment with an increased length of 140 mm, and diameter of 22 mm, and similar to the UV lamps 140 to 143 their respective axes are also vertical. The axes of four of the five ozone generators 150, 151, 152 and 153 are arranged also in the corners of a second imaginary square which is turned by 45°relative to the square where the axes of the four UV-C lamps are located, thereby these axes fall in a circle concentric with the cylinder 120 and arranged in the apex points of an octagon as shown in Fig. 5 which is a schematic cross sectional view of the reaction chamber 130.

Because the inner cylindrical surface of the cylinder 120 is polished to reflect light as a concave mirror (at least in the zone of the reaction chamber 130), and the UV-C lamps 140 to 143 emit UV-C light rays in the 254 nm length of wavelength mostly in radial direction (i.e. normal to their axes), a rather complex multifocal reflection pattern is formed in the interior of the reaction camber 130. This and the use of four UV-C lamps substantially increase the intensity of UV-C light within the chamber compared to the first embodiment, and the efficiency of inactivating all microorganisms that enter the reaction chamber will thereby increase. The ozone generators 150...155 generate ozone along their entire lengths (140 mm) and in the interior of the reaction chamber 130 the simultaneous effects of ozone and UV-C light have a synergy concerning the efficiency of the disinfection. This combined effect is so intensive that even a short travel time of an average air molecule through the reaction chamber of shorter than about 100 ms will be sufficient to inactivate all microorganisms carried by the airflow.

As mentioned in the previous embodiment this killing effect has an optimum that can be adjusted by the pulse parameters of the ozone generators and the UV-C lamps, as well as the flow rate of air. The previously mentioned optimum ranges are applicable in case of this embodiment. However, here one can calculate with a higher airflow volume up to 200 m ³ /hour or above. Fig. 6 shows the top view of the discs 131, 132 made of glass fiber reinforced polyester plates, in which the respective end regions of the UV-C lamps 140...143 and of the ozone generators 150...154 are fixed. A plurality of discrete openings 133 are formed in both discs 131, 132 which occupy part of the area between the central UV-C lamp 155 and the previously described arrangement of further UV-C lamps and ozone generators around it and function as air inflow and outflow passages in and out of the reaction chamber 130. Compared to the surface of the discs 131, 132 the full area of the openings 133 is much smaller, and this design slows down the airflow to ensure optimum travel time for the particles present in the inflowing air, and simultaneously increases the pressure inside the chamber, whereby the operation parameters of the ozone generators will also change and wider pulses will be needed compared to the previous embodiment.

Let us refer again to Fig. 3 showing the general structure of the device 100. Above the reaction chamber 130 a heater 160 is provided which has the task of increasing the temperature of the air stream flowing out from the reaction chamber 130. The reason of heating the air lies in that the higher temperature facilitates recombination of ozone to oxygen. There are several ways how flowing air can be heated, and good examples for this are the widely used hairdryers using different shapes of heating filaments or spirals. A preferred embodiment for a heater 160 usable in this device is shown in Fig. 7 and it comprises a number of resistors 161 designed for dissipating 5W of power each, in this case with a resistance of 33 Ohm and these resistors 161 are arranged spaced from each other along a circle co-axial with the cylinder 120. The cylindrical bodies of the resistors 161 extend parallel to the vertical central axis and together they constitute an imaginary heating cylinder placed around the flow path of the air stream leaving the reaction chamber 120. The control of the device ensures that first the heater 160 is energized and when the operational temperature has been reach, the fan 112 is set to operation and only the stabilization of the flow pattern will the ozone generators and UV-C lamps energized.

In the cylinder 120 above the heater 160 an ozone recombination unit 170 is arranged, which has the design as shown in the previous embodiment, however, the shape of the unit fits to the interior of the cylinder 120. This unit performs its function in a perfect way. Reference is made now to Fig. 8 that shows the upper end part 121 of the device 100 above the ozone recombination unit 170. A perforated circular closing plate 180 is arranged at the upper end of the cylindrical section of the cylinder 120 that allows the disinfected airflow to leave the device in vertical direction. In a preferred embodiment the upper end part 121 of the cylinder 120 is an oblique cut having an elliptical shape, and this has no real functional role but has been chosen from design aspects only. In any way close to the top of the end part 121, and an ozone sensor 181 is arranged which senses the presence of ozone in the out flowing air, and it is connected to the power supply and control unit 70 (Fig. 1) to shut off the generation of ozone in air cleaning mode.

In the interior of the end part 121 an optional scent emitting rod 182 is arranged which add a pre-selected type of scent to the out flowing air and generates a pleasant atmosphere is the room where the device is installed.

The second embodiment of the device has the property of sucking air from every direction, and if it is placed on the middle of a conference table or in m id position of people participating in a meeting, it sucks air from a radius of over 6 m and the disinfected air leaves the device in vertical direction. Participants of the meeting will therefore not be able to infect their neighbours and this is an optimum layout for in person meetings.

Both embodiments of the device can be controlled in such a way that the ozone decontamination portions are inactivated and then air containing high amount of ozone will leave the device, and this mode can be used in the night or when no one is present in the room where the device is functioned. With appropriate programming it can be adjusted that after a period of such disinfection with ozone, the ozone recombination units 60 or 170 are activated and the ozone generation is stopped, and this recombination mode of operation can remove ozone from the room and after a predetermined period people can be allowed.

In any way the most preferred use of the device Is when both ozone generation and recombination are functioning and disinfection takes place when persons are present.

The device according to the invention has several preferred properties on the top of perfect disinfection which include reduces energy consumption, long lifetime, the operation without any chemicals or filters that require maintenance and periodic replacement. While the suggested arrangements of the device represent preferred embodiments different arrangements with other sizes and number of parts can also perform good disinfection effects. The same concerns the use of mirroring internal surfaces, without such design the operation can be also good, perhaps only the energy consumption would be higher.

The adjustment of the operation requires calibration, because the airflow rate, the excitation of the UV-C lamp, the amount of ozone generated and the adjustment of the ozone recombination unit should be coordinated, and this coordination should be based on proper calibration. It can be preferred if in larger spaces instead of using a single device with higher airflow rate, the use of a plurality of smaller devices distributed in the area can be more preferred.

The invention cannot be limited therefore to the preferred embodiments shown.