WO2023047220A1

WO2023047220A1 - Air cleaning system

Info

Publication number: WO2023047220A1
Application number: PCT/IB2022/058331
Authority: WO
Inventors: Eros Matteo VENTURINI
Original assignee: Venturini Eros Matteo
Priority date: 2021-09-27
Filing date: 2022-09-05
Publication date: 2023-03-30
Also published as: IT202100024689A1

Abstract

The invention relates to an air cleaning system (1) for sanitizing contaminated air in a closed environment, comprising an upper inlet mouth (11), into which contaminated air from the environment flows, a lower outlet mouth (12), into which clean air flows towards the environment, and a fluid path (10) extending between said inlet mouth (11) and said outlet mouth (12). The air cleaning system (1) comprises, along the fluid path (10) : - a heating group (2), suitable for heating the incoming contaminated air; - a sterilization group (3), suitable for sterilizing heated contaminated air; - an ionization group (4), suitable for performing an ionization action on the heated and sterilized contaminated air, purifying it from viruses and bacteria, so as to generate clean air coming out of the outlet mouth (12). The invention also relates to an air cleaning method performed by an air cleaning system (1) according to the invention.

Description

"AIR CLEANING SYSTEM" DESCRIPTION

Field of application

[0001] The present invention relates to an air cleaning system for cleaning contaminated air, preferably in a closed environment, and to a method for cleaning air by means of said air cleaning system.

[0002] The present invention finds use in the field of healthcare and illness prevention, and more specifically in the purification of air in closed environments, such as homes, warehouses, offices, hospitals, schools, stores and the like.

[0003] In some situations, the air in a closed location is contaminated with pollution and dust. The factors responsible for this pollution are found in the most mundane of day-to-day activities, such as the use of certain types of detergents that are too aggressive, the presence of furniture treated with chemical substances, and simple accumulations of dirt or animal hair deposited on surfaces.

[0004] In addition, a wide range of viruses and bacteria circulate in such environments, putting the potentially vulnerable people who occupy them at risk. Recently, in particular, various scientific studies have shown that the new coronavirus COVID-19 remains in the air for up to 3 hours after aerosolization .

[0005] Therefore, it is essential to keep or make the air of an environment uncontaminated.

[0006] There are many known solutions that consider and try to overcome this kind of problem.

[0007] First, a simple solution is to air the rooms frequently .

[0008] Disadvantageously, this approach is only able to be applied effectively and consistently during the warmer months. In fact, in the colder months, opening windows results in excessive heat loss and thus a considerable increase in the consumption of heating systems. In addition, there is no control over the actual cleanliness of the air, and so this method is not safe.

[0009] Typically, specific technical solutions for air treatment, such as purifiers or sanitizers, are preferred. Such devices are known and classified according to the technology used.

[00010] Ozone air purifiers have become widespread. Such devices take advantage of the release of high amounts of ozone to eliminate microorganisms present in the air.

[00011] Disadvantageously, such devices are potentially harmful to health, releasing high amounts of ozone that often exceed the recommended limits. [00012] An alternative solution involves the use of ionizing purifiers. Such devices involve the use of ionizers inside them, which are able to break down microparticles in the air by positively and/or negatively charging them through an electrostatic process and then forcing them to aggregate.

[00013] Disadvantageously, such technology on its own is unable to completely eliminate odors, pollutants, and harmful particles.

[00014] Another well-known solution involves the use of air purifiers with a mechanical filter, such as a HEPA filter .

[00015] Disadvantageously, viruses that are captured by a mechanical filter without an electrostatic process remain alive in the filter, which poses the risk of spreading infections from the device itself. For this reason, such filters must be replaced frequently.

[00016] Disadvantageously, moreover, the cost of related replacement filters is considerable.

Solution of the invention

[00017] Therefore, there appears to be a significant need to provide an air cleaning system capable of overcoming the drawbacks typical of the prior art.

[00018] This requirement is met by an air cleaning system according to the appended independent claim 1 and by the air cleaning method according to independent claim 19 . The claims dependent thereon describe preferred or advantageous embodiments of the invention, comprising further advantageous features .

Description of the drawings

[ 00019 ] The features and advantages of the air cleaning system will become apparent from the description below of a number of preferred embodiments , given by way of nonlimiting example , with reference to the attached figures , in which : figure 1 shows a schematic view of the air cleaning system according to an embodiment of the invention; figure 2 shows a schematic view of the air cleaning system according to a further embodiment of the invention; figure 3 shows a schematic view of an air cleaning system according to yet a further embodiment of the invention; figure 4 shows a schematic view of an air cleaning system according to yet a further embodiment of the invention; figure 5 shows a sectional view of an air cleaning system according to the present invention, according to a preferred embodiment .

Detailed description [00020] With reference to the above figures, an air cleaning system for cleaning contaminated air in a closed environment has been collectively denoted by reference number 1.

[00021] The term "cleaning" should be understood here to mean the whole of three processes that are carried out on contaminated air consecutively: heating, sterilization, and ionization.

[00022] In accordance with the invention, for example with reference to the attached figure 1, the air cleaning system 1 comprises an upper inlet mouth 11, a lower outlet mouth 12, and a fluid path 10 extending between said inlet mouth 11 and said outlet mouth 12.

[00023] Contaminated air from the environment flows into the inlet mouth 11, and clean air flows into said outlet mouth 12 towards the environment.

[00024] The term "clean air" means air, previously contaminated, that has been heated, sterilized, and ionized. In other words, clean air means air in which viruses, dust, bacteria, pollutants and the like have been eliminated and broken down.

[00025] The air cleaning system 1 according to the invention comprises, along said fluid path 10: a heating group 2, fluidly connected to said inlet mouth 11 suitable for heating the incoming contaminated air from said inlet mouth 11; a sterilization group 3, fluidly connected to said heating group 2 for receiving heated contaminated air, suitable for sterilizing said heated contaminated air; an ionization group 4, fluidly connected to said sterilization group 3 for receiving heated and sterilized contaminated air, wherein the ionization group 4 performs an ionization action on the heated and sterilized contaminated air purifying it from viruses and bacteria, so as to generate clean air coming out of the outlet mouth 12.

[00026] Clean air is understood to mean contaminated air that has undergone the synergistic combination of heating, sterilization and ionization treatments, performed successively in the heating group 2, in the sterilization group 3, and in the ionization group 4, respectively .

[00027] In accordance with an embodiment of the invention, the heating group 2 comprises a fan 21 suitable for pushing the contaminated air along said fluid path 10. [00028] In accordance with an embodiment of the invention, the heating group 2 comprises a heating plate 22 suitable for heating the contaminated air.

[00029] According to one embodiment, the sterilization group 3 comprises a sterilization device 31. Such a sterilization device 31 comprises a UVC emitter 30 which irradiates the heated contaminated air so as to sterilize it .

[00030] According to a further embodiment, with reference to the example in figure 3, the sterilization group 3 also comprises an auxiliary sterilization device 31' arranged parallel to the sterilization device 31. This auxiliary sterilization device 31' comprises an auxiliary UVC emitter 30' which irradiates the heated contaminated air so as to sterilize it.

[00031] According to yet a further embodiment of the invention, for example with reference to the attached figure 4, the sterilization group 3 comprises a plurality of auxiliary sterilization devices 31' arranged parallel to the sterilization device 31.

[00032] Advantageously, the presence of a plurality of auxiliary sterilization devices 31' allows a larger volume of heated contaminated air to be sterilized simultaneously . [00033] Preferably, the sterilization device 31 is delimited by reflective side walls, for example made of polished stainless steel, which are such as to amplify the sterilization effect by irradiation.

[00034] Preferably, the auxiliary sterilization device 31' is delimited by reflective side walls, for example made of polished stainless steel, which are such as to amplify the sterilization effect by irradiation.

[00035] Preferably, the ionization group 4 comprises an ionizer 40 which generates a negative ionization on the air .

[00036] In other words, the ionizer 40 generates air rich in negative ions. Negative ions bind to particles suspended in the air (dust, odors, smoke, pollen, as well as viruses and bacteria) and charge them electrostatically. In this way, virus and bacteria particles tend to bind to the surfaces they encounter instead of remaining suspended in the air.

[00037] According to a preferred embodiment, it is the heated and sterilized contaminated air that is the subject of the negative ionization action.

[00038] Advantageously, therefore, as a result of the ionization in the ionization group 4, virus and bacteria particles in the heated and sterilized contaminated air are broken down and separated therefrom. [00039] In other words, clean air is generated through ionization .

[00040] Preferably, the air cleaning system 1 is configured in such a way that the air travels over an obligatory path along said fluid path 10, said obligatory path being such as to allow optimal space occupancy in said heating group 2, sterilization group 3, and ionization group 4.

[00041] In a preferred embodiment, with reference to an example shown in figure 5, the air cleaning system 1 is a tubular duct having a side shell and comprising said heating group 2, said sterilization group 3, and said ionization group 4.

[00042] Preferably, the heating plate 22 is arranged coaxially to said tubular duct.

[00043] Even more preferably, in the heating group 2, the side shell of the tubular duct is lined with a predetermined thickness of an insulating material 23 so as to thermally insulate said heating group.

[00044] Preferably, the tubular duct is a stainless steel pipe having a cross section with a constant diameter of 100 mm.

[00045] According to one embodiment, the air cleaning system 1 comprises an outlet sleeve 41 on which the outlet mouth 12 is formed, said outlet sleeve 41 being stably engaged, for example welded, with the tubular duct .

[ 00046 ] Preferably, the air cleaning system 1 comprises a PVC pipe 42 fixed internally to said outlet s leeve 41 . [ 00047 ] Preferably, the ioni zer 40 is mounted on said PVC pipe 42 .

[ 00048 ] According to an embodiment of the invention, the air cleaning system 1 comprises a compressor 7 positioned upstream of the air inlet mouth 11 , suitable for aspirating contaminated air from the environment at an initial pressure Pl and introducing it into the heating group 2 through the air inlet mouth 11 at a desired pressure P2 which is higher than said initial pressure Pl .

[ 00049 ] Preferably, the air cleaning system comprises pressure detection means which detect the pressure within the heating group .

[ 00050 ] Preferably, the compressor 7 is operable upon the detection, by the pressure detection means , of a pressure less than said desired pressure P2 , and is blockable upon the detection, by the pressure detection means , of a pressure greater than or equal to said desired pressure P2 . [00051] According to a preferred embodiment, the air cleaning system 1 comprises flow control means suitable for adjusting the air flow along the fluid path 10.

[00052] Preferably, for example with reference to the attached figure 2, such flow control means comprise:

- a first valve group 6 between the heating group 2 and the sterilization group 3;

- a second valve group 6' between the sterilization group 3 and the ionization group 4;

- an electronic control group 5 operatively connected to said first valve group 6 and second valve group 6' .

[00053] The electronic control group 5 is configured for controlling the first valve group 6 so as to adjust the passage of heated contaminated air from the heating group 2 to the sterilization group 3, and configured for controlling the second valve group 6' so as to adjust the passage of heated and sterilized contaminated air from the sterilization group 3 to the ionization group 4.

[00054] According to an embodiment of the invention, the heating group 2 comprises temperature detection means suitable for identifying the temperature T of the heated contaminated air therein.

[00055] Preferably, the first valve group 6 comprises a first valve 61. [00056] In accordance with a preferred embodiment, the electronic control group 5 keeps the first valve 61 closed upon the detection, by the temperature detection means, of a temperature T which is lower than a threshold temperature Ts, so as to block the passage of heated contaminated air from the heating group 2 to the sterilization group 3.

[00057] In accordance with a preferred embodiment, the electronic control group 5 opens the first valve 61 upon the detection, by the temperature detection means, of a temperature T which is higher than the threshold temperature Ts, so as to allow the passage of heated contaminated air from the heating group 2 to the sterilization group 3 through said first valve 61.

[00058] Preferably, the threshold temperature Ts is between 30°C and 50°C.

[00059] Even more preferably, the threshold temperature Ts is 40°C.

[00060] According to an embodiment of the invention, the air cleaning system 1 comprises a first fluid stretch 100 extending between the first valve 61 and the sterilization group 3.

[00061] Preferably, the first valve 61 is a pressure switch solenoid valve suitable for allowing air flow by pressure difference. [ 00062 ] Preferably, the first valve group 6 further comprises a main inlet valve 63 positioned between said first fluid stretch 100 and the sterili zation device 31 , and an auxiliary inlet valve 64 positioned between said first fluid stretch 100 and the auxiliary sterili zation device 31 ' .

[ 00063 ] According to a preferred embodiment , the electronic control group 5 is configured for controlling the main inlet valve 63 so as to allow the passage of heated contaminated air from the first fluid stretch 100 to the sterili zation device 31 and is configured for controlling the auxiliary inlet valve 64 so as to allow the passage of heated contaminated air from the first fluid stretch 100 to the auxiliary sterili zation device 31 ' , so that said sterili zation device 31 and said auxiliary sterili zation device 31 ' simultaneously operate on a relevant amount of heated contaminated air, so as to generate a relevant amount of sterili zed, heated, contaminated air to be received by the ioni zation group 4 .

[ 00064 ] Preferably, the main inlet valve 63 and the auxiliary inlet valve 64 are pressure switch solenoid valves suitable for al lowing air flow by pressure di f ference . [00065] According to an embodiment, the air cleaning system 1 comprises a timer suitable for detecting the actual irradiation time t-eff wherein the UVC emitter 30 and/or the auxiliary UVC emitter 30' irradiates the heated contaminated air inside the sterilization device 31 and/or the auxiliary sterilization device 31', respectively, and suitable for comparing said actual irradiation time with a predetermined optimal UVC exposure time t-opt.

[00066] Preferably, said optimal UVC exposure time t- opt is between 15 seconds and 25 seconds.

[00067] Even more preferably, said optimal UVC exposure time t-opt is 20 seconds.

[00068] In an embodiment, the second valve group 6' comprises a second valve 62 positioned between the sterilization device 31 and the ionization group 4.

[00069] Preferably, the second valve 62 is a pressure switch solenoid valve suitable for allowing air flow by pressure difference.

[00070] Preferably, the second valve group 6' further comprises a second auxiliary valve 62' positioned between the auxiliary sterilization device 31' and the ionization group 4. [00071] Preferably, the second auxiliary valve 62 is a pressure switch solenoid valve suitable for allowing air flow by pressure difference.

[00072] According to an advantageous variant, the electronic control group 5 keeps the second valve 62 and/or the second auxiliary valve 62' closed, respectively, upon the detection, by the timer, of an actual irradiation time t-eff which is lower than the optimal exposure time t-opt, in the sterilization device 31 and/or in the auxiliary sterilization device 31', respectively, so as to block the passage of sterilized, heated, contaminated air from the sterilization group 3 to the ionization group 4.

[00073] According to an advantageous variant, the electronic control group 5 opens the second valve 62 and/or the second auxiliary valve 62', respectively, upon the detection, by the timer, of an actual irradiation time t-eff, which is greater than or equal to the optimal exposure time t-opt, in the sterilization device 31 and/or in the auxiliary sterilization device 31', respectively, so as to allow the passage of sterilized and heated contaminated air from the sterilization group

3 to the ionization group 4. [00074] Preferably, the electronic control group 5 opens the second valve 62 and/or the second auxiliary valve 62' for a period between 1 and 5 seconds.

[00075] Even more preferably, the electronic control group 5 opens the second valve 62 and/or the second auxiliary valve 62' for a period of 3 seconds.

[00076] The present invention also relates to an air cleaning method, comprising the steps of: a) providing an air cleaning system 1 according to the invention; b) receiving, in the heating group 2, incoming contaminated air through the inlet mouth 11; c) heating said contaminated air in said heating group 2; d) allowing the flow of heated contaminated air into the sterilization group 3; e) sterilizing said heated contaminated air in said sterilization group; f) allowing the flow of sterilized and heated contaminated air into the ionization group 4; g) subjecting to ionization said sterilized and heated contaminated air in said ionization group 4; h) allowing the flow of clean air from the ionization group 4 into the environment through the outlet mouth 12. [00077] Innovatively, the air cleaning system that is the object of the present invention fully fulfills the intended objective by overcoming the typical problems of the prior art.

[00078] Innovatively, in fact, the present invention combines different air treatment technologies, achieving effective and efficient results.

[00079] Advantageously, the synergistic combination of heating, sterilization, and ionization treatments makes it possible to achieve an effective air cleaning treatment .

[00080] Advantageously, moreover, the air cleaning system performs continuous and constant air disinfection, operating in environments safely inhabited by occupants.

[00081] Advantageously, in fact, the air cleaning system avoids the release of ozone and/or other substances detrimental to health.

[00082] Advantageously, the air cleaning system allows the virus in the contaminated air to be weakened prior to sterilization, thus increasing the effectiveness of the cleaning action.

[00083] Advantageously, the air cleaning system is small in size. In other words, the air cleaning system is able to be miniaturized and is portable.

[00084] Advantageously, in the miniaturized form, the air cleaning system is mountable in a confined environment, such as inside a car. [ 00085 ] Advantageously, the presence of an auxiliary sterili zation device makes it possible to double the sterili zable air flow rate for the same irradiation time . [ 00086 ] Advantageously, the presence of a plurality of auxiliary sterili zation devices makes it possible to considerably increase the flow rate of sterili zable air for the same irradiation time .

[ 00087 ] Advantageously, the air cleaning system ensures perfect shielding of UVC rays .

[ 00088 ] Advantageously, the flow control means make it possible to control the passage of air along the fluid path .

[ 00089 ] Advantageously, the first valve group allows the passage of heated contaminated air from the heating group to the sterili zation group only once the air has reached an optimal heating temperature for virus weakening .

[ 00090 ] Advantageously, the second valve group allows the passage of heated and sterili zed contaminated air from the sterili zation group to the ioni zation group only once the time required for complete irradiation has elapsed .

[ 00091 ] Advantageously, the configuration of the air cleaning system that forces air to flow from the top down allows contaminated air to be aspirated at a height close to the respiratory tracts of the occupants of the environment in which the air cleaning system has been placed .

[00092] Advantageously, the configuration of the air cleaning system that forces air to flow from the top down causes vortices to form in the heating group as a result of the temperature difference, which allows better and more even heat distribution over the entire volume of air to be heated.

[00093] Advantageously, the air cleaning system is usable also in a horizontal position, that is to say with the inlet and outlet mouths lying substantially in a plane parallel to the floor plane of the environment in which the system has been placed. For example, the system may be mounted to the walls of a building, parallel to the ceiling.

[00094] Advantageously, the stainless steel sterilization device amplifies the effect of sterilization by irradiation.

[00095] Advantageously, the stainless steel sterilization device resists the action of UV rays, avoiding degradation over time.

[00096] A person skilled in the art may, in order to meet specific needs, make several changes to the embodiments of this invention or substitutions of elements with other functionally equivalent ones .

[ 00097 ] These variants are also contained within the scope of protection as defined by the following claims . List of reference numbers :

1 air cleaning system

10 fluid path

100 first fluid stretch

11 inlet mouth

12 outlet mouth

2 heating group

21 fan

22 heating plate

3 sterili zation group

30 UVC emitter

31 sterili zation device

31 ' auxiliary sterili zation device

4 ioni zation group

40 ioni zer

5 electronic control group

6 first valve group

6 ' second valve group

61 first valve

62 second valve

63 main inlet valve

64 auxiliary inlet valve 7 compressor

T temperature

Ts threshold temperature t-ef f ef fective irradiation time t-opt optimal UVC exposure time

Claims

1. An air cleaning system (1) for sanitizing contaminated air in a closed environment, comprising an upper inlet mouth (11) , a lower outlet mouth (12) , and a fluid path (10) extending between said inlet mouth (11) and said outlet mouth (12) , wherein contaminated air from the environment flows into said inlet mouth (11) , and into said outlet mouth (12) , clean air flows towards the environment; said air cleaning system (1) comprising, along said fluid path (10) :

- a heating group (2) , fluidly connected to said inlet mouth (11) suitable for heating the incoming contaminated air from said inlet mouth (11) ;

- a sterilization group (3) , fluidly connected to said heating group (2) for receiving heated contaminated air, suitable for sterilizing heated contaminated air; an ionization group (4) , fluidly connected to said sterilization group (3) for receiving heated and sterilized contaminated air, wherein the ionization group (4) performs an ionization action on the heated and sterilized contaminated air purifying it from viruses and bacteria, so as to generate clean air coming out of the outlet mouth (12) .

2. Air cleaning system (1) according to claim 1, wherein said heating group (2) comprises a fan (21) suitable for pushing the contaminated air along said fluid path (10) .

3. Air cleaning system (1) according to any one of the preceding claims, wherein said heating group (2) comprises a heating plate (22) suitable for heating the contaminated air.

4. Air cleaning system (1) according to any one of the preceding claims, wherein the sterilization group (3) comprises a sterilization device (31) , comprising a UVC emitter (30) which irradiates said heated contaminated air so as to sterilize it.

5. Air cleaning system (1) according to claim 4, wherein the sterilization group (3) comprises an auxiliary sterilization device (31' ) arranged parallel to the sterilization device (31) , said auxiliary sterilization device (31' ) comprising an auxiliary UVC emitter (30' ) which irradiates said heated contaminated air so as to sterilize it.

6. Air cleaning system (1) according to claim 4 or 5, wherein the sterilization device (31) and/or the auxiliary sterilization device (31' ) are delimited by reflective side walls, for example made of polished stainless steel, which are such as to amplify the sterilization effect by irradiation.

7. Air cleaning system (1) according to any one of the preceding claims, wherein the ionization group (4) comprises an ionizer (40) which generates a negative ionization on the air.

8. Air cleaning system (1) according to any one of the preceding claims, comprising a compressor (7) positioned upstream of the air inlet mouth (11) , suitable for aspirating contaminated air from the space at an initial pressure (Pl) and introduce it into the heating group (2) through the air inlet mouth (11) at a desired pressure (P2) which is higher than said initial pressure (Pl) .

9. Air cleaning system (1) according to any one of the preceding claims, comprising flow control means suitable for adjusting the air flow along the fluid path (10) .

10. Air cleaning system (1) according to claim 9, wherein said flow control means comprise:

- a first valve group (6) between the heating group (2) and the sterilization group (3) ;

- a second valve group (6' ) between the sterilization group (3) and the ionization group (4) ;

- an electronic control group (5) operatively connected to said first valve group (6) and second valve group (6' ) , configured to control the first valve group (6) so as to adjust the passage of heated contaminated air from the heating group (2) to the sterilization group (3) , and configured to control the second valve group (6' ) so as to adjust the passage of heated and sterilized contaminated air from the sterilization group (3) to the ionization group (4) .

11. Ai r cleaning system (1) according to any one of the preceding claims, wherein the heating group (2) comprises temperature detection means suitable for identifying the temperature (T) of the heated contaminated air therein.

12. Air cleaning system (1) according to claims 10 and 11, wherein the first valve group (6) comprises a first valve (61) , and wherein said electronic control group (5) keeps the first valve (61) closed upon the detection, by the temperature detection means, of a temperature (T) which is lower than a threshold temperature (Ts) , so as to block the passage of heated contaminated air from the heating group (2) to the sterilization group (3) , and wherein said electronic control group (5) opens the first valve (61) upon the detection, by the temperature detection means, of a temperature (T) which is higher than the threshold temperature (Ts) , so as to allow the passage of heated contaminated air from the heating group

(2) to the sterilization group (3) through said first valve ( 61 ) .

13. Ai r cleaning system (1) according to claims 5 and 12, comprising a first fluid stretch (100) extending between the first valve (61) and the sterilization group (3) ; wherein the first valve group (6) further comprises a main inlet valve (63) positioned between said first fluid stretch (100) and the sterilization device (31) and an auxiliary inlet valve (64) positioned between said first fluid stretch (100) and the auxiliary sterilization device ( 31 ' ) ; and wherein the electronic control group (5) is configured to control the main inlet valve (63) so as to allow the passage of heated contaminated air from the first fluid stretch (100) to the sterilization device (31) and is configured to control the auxiliary inlet valve (64) so as to allow the passage of heated contaminated air from the first fluid stretch (100) to the auxiliary sterilization device (31' ) , so that said sterilization device (31) and said auxiliary sterilization device (31' ) simultaneously operate on a respective amount of heated contaminated air, so as to generate a respective amount of sterilized, heated, contaminated air to be received by the ionization group (4) .

14. Ai r cleaning system (1) according to claim 4 or 5, comprising a timer suitable for detecting the actual irradiation time (t-eff ) , wherein the UVC emitter (30) and/or the auxiliary UVC emitter (30' ) irradiates the heated contaminated air inside the sterilization device 27

(31) and/or the auxiliary sterilization device (31' ) , respectively, and suitable for comparing said actual irradiation time with a predetermined optimal UVC exposure time (t-opt) .

15. Ai r cleaning system (1) according to claims 4 and 10, wherein the second valve group (6' ) comprises a second valve (62) positioned between the sterilization device (31) and the ionization group (4) .

16. Air cleaning system (1) according to claim 15, wherein the second valve group (6' ) further comprises a second auxiliary valve (62' ) positioned between the auxiliary sterilization device (31' ) and the ionization group ( 4 ) .

17. Ai r cleaning system (1) according to claim 15 or 16, wherein the electronic control group (5) keeps the second valve (62) and/or the second auxiliary valve (62' ) closed, respectively, upon the detection, by the timer, of an actual irradiation time (t-eff) which is lower than the optimal exposure time (t-opt) , in the sterilization device (31) and/or in the auxiliary sterilization device (31' ) , respectively, so as to block the passage of sterilized, heated, contaminated air from the sterilization group (3) to the ionization group (4) ; and wherein said electronic control group (5) opens the second valve and/or the second auxiliary valve (62' ) , respectively, upon the detection, by the timer, of an actual irradiation time (t-eff ) , which is greater than or equal to the optimal exposure time (t-opt) , in the sterilization device (31) and/or in the auxiliary sterilization device (31' ) , respectively, so as to allow the passage of sterilized and heated contaminated air from the sterilization group (3) to the ionization group (4) .

18. An air cleaning method comprising the steps of: a) providing an air cleaning system (1) according to any one of the preceding claims; b) receiving, in the heating group (2) , incoming contaminated air through the inlet mouth (11) ; c) heating said contaminated air in said heating group (2) ; d) allowing the flow of heated contaminated air into the sterilization group (3) ; e) sterilizing said heated contaminated air in said sterilization group; f) allowing the flow of sterilized, heated, contaminated air into the ionization group (4) ; g) subjecting to ionization said sterilized and heated contaminated air in said ionization group (4) ; h) allowing the flow of clean air from the ionization group (4) into the environment through the outlet mouth (12) .