Air treatment unit and a method for controlling such air treatment unit

Abstract

The disclosure relates to an air treatment unit (1) for providing treated air in a defined space (S), the air treatment unit (1) comprising; a desiccant rotor (100); a process air circuit (11) arranged to conduct process air (110) through a process section (111) of the desiccant rotor (100); and a regeneration air circuit (12) arranged to conduct regeneration air (120) through a regeneration section (121) of the desiccant rotor (100); wherein the air treatment unit (1) further comprises a controllable irradiation arrangement (13) comprising at least one integrated UV-C emitter (130) arranged to, when active, emit UV-C light (2) to reduce the amount of viable microorganisms in the process air (110). The disclosure further relates to a method for controlling such an air treatment unit (1).

Description

[0001] AIR TREATMENT UNIT AND A METHOD FOR CONTROLLING SUCH AIR TREATMENT UNIT

[0002] TECHNICAL FIELD

[0003] The present invention relates to an air treatment unit and a method for controlling such air treatment unit. Specifically, the present invention relates to an air treatment unit and a method for controlling such air treatment unit as defined by the appended claims.

[0004] BACKGROUND ART

[0005] Air treatment units or systems of various kinds are commonly used for providing treated air into a defined space to improve indoor air quality. Within the technical field of air treatment, different types of air treatment units are used that comprises a sorption media for adsorbing or absorbing gases. Such air treatment unit may for example comprise a desiccant rotor where the sorption media, also referred to as rotor media, is configured for absorbing moisture. The rotor rotates slowly between a process and a regeneration airstream and typically comprises a process section and a regeneration section. The process air flows through the channels of the rotor media and the rotor media either adsorbs or absorbs moisture. When the rotor rotates, the rotor media is heated by the hot regeneration air, and the rotor media releases its moisture into the regeneration air. Following regeneration, the rotor rotates back into the process airstream, where the process repeats itself.

[0006] Such traditional air treatment units often face limitations in effectively removing a wide range of contaminants present in the process air. Common air treatment systems may address particulate matter to some extent but struggle with eliminating pollutants such as volatile organic compounds (VOCs), allergens, microbes and mycobacteria. Recent pandemics has shown the importance of removing such matter from indoor air. In order to solve the problem of airborne pollutants and microorganisms there exist several different solutions which sometimes are combined with an air treatment unit. Examples of such solutions include High Efficiency Particulate Air Filters (HEPA), nano-filters such as Polyacrylonitrile (PAN) filters, ultrathin silk nanofibril membranes (SNF) or composite membranes using soy proteins.

[0007] However, these filters / membranes effectiveness against microbes might be limited.

[0008] There is thus a need to develop an improved air treatment unit which reduces the amount of viable microorganisms in the treated air.

[0009] SUMMARY OF THE INVENTION

[0010] It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above- mentioned problem.

[0011] An object of the present invention is thus to achieve an air treatment unit and a method for controlling such an air treatment unit, which reduces the amount of viable microorganisms in the treated air.

[0012] Another object of the present invention is to achieve an air treatment unit and a method for controlling such an air treatment unit, which is particularly suited for applications in medical, industrial and manufacturing environments.

[0013] Hence, according to a first aspect there is provided an air treatment unit for providing treated air in a defined space, the air treatment unit comprising; a desiccant rotor, a process air circuit arranged to conduct process air through a process section of the desiccant rotor, and a regeneration air circuit arranged to conduct regeneration air through a regeneration section of the desiccant rotor; wherein the air treatment unit further comprises a controllable irradiation arrangement comprising at least one integrated UV-C emitter arranged to, when active, emit UV-C light to reduce the amount of viable microorganisms in the process air.

[0014] The air treatment unit is configured to provide treated air to a defined space. The desiccant rotor will adsorb moisture in the process air and will also adsorb microorganisms to some extent, specifically larger microorganisms. However, smaller microorganisms or particles, which are easier to inhale and more easily will reach humans respiratory organs, may still be present in the process air. By using a controllable irradiation arrangement with an integrated UV-C emitter, the process air entering the air treatment unit will be exposed to UV-C light in a controlled manner and the smaller microorganisms can be inactivated. UV-C light is known for its ability to kill bacteria and virus and adding that to a conventional air treatment unit with a desiccant rotor will provide an additional layer of air treatment. The irradiation arrangement specifically targets and reduces viable microorganisms in the process air being provided to the defined space, promoting a healthier and safer environment. UV-C light can kill various pathogens, such as virus particles like COVID-19, and are consequently beneficial in environments like hospitals, industrial- and manufacturing facilities among others. In a small and controlled amount, the UV-C light is highly effective for sterilization, disinfection and sanitation of air. By implementing a UV-C emitting arrangement in for example a dehumidifier, it is possible to control the climate control prospect while regulating and controlling the amount of viable microorganisms in the process air. Integrating the UV-C emitters directly into the air treatment unit creates an irradiation chamber for the process air and simplifies the overall design and operation. The integration ensures that UV-C light is efficiently applied on the process air, maximizing its effectiveness in reducing the number of viable microorganisms. Compared to known solutions where filters or other separate equipment are added in series with the air treatment unit for providing additional air treatment steps, the integration of the UV-C emitters in the present invention saves both space, time and cost. By combining desiccant rotor technology with UV-C irradiation, the air treatment unit offers a comprehensive solution for managing both humidity levels and microbial contamination in the treated air.

[0015] In addition to UV-C light exposure, several other factors can affect the infectivity of airborne microorganisms. Such factors include relative humidity, temperature, aerosolization medium and the chemical composition of the air. Specifically, depending on the type of microorganism, the relative humidity and temperature may affect the infectivity of the microorganisms as well as the capability of inactivating the microorganisms by means of UV-C light. Thus, different parameters may impact the efficiency or functionality of the irradiation arrangement and the inactivation rate of the UV-C emitter. The process air is outdoor air entering the air treatment unit. For some microorganisms, the inactivation rate will decrease as the temperature of the process air increases. For any temperature, the inactivation rate of some microorganisms will be lower at very high relative humidity. However, some viruses are more likely to spread in cold and dry climates and the irradiation arrangement may therefore be controlled differently. Different microorganisms also require different exposure of UV-C light in order to be killed or inactivated. The total exposure of UV-C light may depend on the number of UV-C emitters, the power or intensity of the active UV-C emitter(s) and the time of exposure. Depending on the targeted biomolecule, the desiccant rotor, the process air flow and the irradiation arrangement can be controlled to achieve conditions that increases the inactivation rate of the irradiation arrangement. Thus, by combining the desiccant rotor and the irradiation arrangement comprising at least one UV-C emitter, optimal conditions for inactivation of target microorganisms can be achieved.

[0016] The air treatment unit may comprise an outer housing, enclosing the desiccant rotor, process air circuit, regeneration air circuit and irradiation arrangement. It is thus clear that the air treatment unit is a single unit, which may be connected to other air treatment units, such as for example a condenser unit or similar. Having an irradiation arrangement integrated in such air treatment unit will reduce the risk of harming humans in the vicinity of the air treatment unit since the light from the UV-C emitter will be limited to the inside of the air treatment unit. Thus, the outer housing of the air treatment unit will reduce the risk of harming humans with the UV- C light.

[0017] The irradiation arrangement being controllable means that the irradiation arrangement is arranged in communication with a control unit, which controls the irradiation arrangement. The control unit may be configured to control the activation of at least one UV-C emitter. The irradiation arrangement being controllable increases flexibility and allows the air treatment unit to only use UV-C light when needed or desired. Thus, the UV-C emitter does not have to be active whenever the air treatment unit is active.

[0018] At least one UV-C emitter may be a UV-C emitting lamp or bulb. Ultraviolet (UV) light is a form of electromagnetic radiation with wavelengths shorter than that of visible light, but longer than X-rays. UV light is divided into three intervals: UV-A (320-400 nm), UV-B (280-320nm) and UV- C (200-280 nm). UV-C light is thus a short-wave UV light with germicidal characteristics. UV-C light is an ionizing radiation at shorter wavelengths, which is completely absorbed by the ozone layer and atmosphere. UV-C light damages DNA and sterilizes surfaces with which it comes into contact. For humans, exposure of the skin to UV light should be avoided, as well as exposure to the eyes.

[0019] It is to be understood that the irradiation arrangement may be configured to kill or inactivate a specific target pathogen or target microorganism in the process air. It is known that bacteria, viruses, fungal spores and environmental organisms vary in susceptibility to UV-C light. Thus, if it is desired to inactivate or kill a particular target pathogen in the process air, the irradiation arrangement may comprise a specific UV-C emitter with an adapted effect or intensity for killing said target pathogen and / or the irradiation arrangement may be controlled based on the target pathogen.

[0020] In some examples, at least a part of the air treatment unit comprises a protective coating configured to protect the air treatment unit from the UV-C light emitted by the at least one UV- C emitter. There might be parts of the air treatment unit that comprises plastic material, and UV-C light could potentially have a damaging effect on such materials. It would therefore be beneficial if the UV-C sensitive parts of the air treatment unit are covered with a protective coating. As an example, the inside of the outer housing of the air treatment unit may comprise protective coating.

[0021] In some examples, the air treatment unit further comprises a reflective element arranged in association with the at least one UV-C emitter. The reflective element suitably comprises a reflective material to reflect the emitted UV-C light. This will significantly increase the reflectivity inside the air treatment unit and increase the radiant power of the UV-C light applied on the process air. The reflective element may be a separate element, such as a metal plate or similar, or it may be a coating on a part of the air treatment unit.

[0022] The protective coating and the reflective element may be integrated with each other. Thus, the protective coating may also be reflective. The reflective element may thus be a protective coating that is added on various surfaces of the air treatment unit. Such protective and reflective coating may be applied on the inside of the outer housing of the air treatment unit.

[0023] In some examples, the at least one UV-C emitter is a FAR-UVC emitter. The shorter wavelengths in the UVC range are the so-called "Far-UVC" spectrum. This is between 200-230 nm. Far-UVC light is equally or more damaging to pathogens as compared to UVC light at 254 nm but with far less hazard to humans. Far-UVC has a much shorter penetration depth than longer wavelength UVC radiation. It is absorbed by the peptide bond in amino acid and is blocked by the stratum corneum layer of the skin and it is also blocked by the cornea of the eye. Therefore, Far-UVC is less harmful for humans and is therefore suitable for integration in an air treatment unit.

[0024] The irradiation arrangement may comprise multiple UV-C emitters. The irradiation arrangement may comprise at least one UV-C emitter arranged upstream of the desiccant rotor. This way, the process air (outdoor air) entering the air treatment unit will immediately be exposed to UV- C light and microorganisms will be killed or inactivated before entering the desiccant rotor. This is advantageous in that less viable microorganisms will be absorbed in the rotor media of the desiccant rotor and the risk for pathogen growth in the desiccant rotor is reduced. This will also reduce the risk for unwanted odors. Thus, arranging at least one UV-C emitter upstream of the desiccant rotor may increase the lifetime of the desiccant rotor and disinfect the process air. Furthermore, as previously discussed, some microorganisms may be easier to inactivate at higher relative humidity and it may therefore be advantageous to arrange at least one UV-C emitter upstream of the desiccant rotor.

[0025] The irradiation arrangement may additionally or alternatively comprise at least one UV-C emitter arranged downstream of the desiccant rotor. This way, the process air will be exposed to UV-C light after having passed through the desiccant rotor and before being provided into the defined space. This may be advantageous since the humidity of the process air at that stage is reduced and the efficiency of the inactivation by means of the UV-C light may be increased for those microorganisms that are easier to inactivate at lower relative humidity. The inactivation rate may be increased downstream of the desiccant rotor also because less microorganisms in the process air downstream of the desiccant rotor will comprise the protective layer of water coating that is the case in bioaerosols. The particles in the dehumidified process air will also be smaller in size, which may facilitate inactivation by means of the UV-C emitter. It is to be understood that the irradiation arrangement may comprise UV-C emitters both upstream and downstream of the desiccant rotor. Since the internal space of the air treatment unit is limited, the process air will not have a very long time of exposure, and it could therefore be beneficial to arrange UV-C emitters both upstream and downstream of the desiccant rotor, to increase the process air's exposure of the UV-C light. The position of the UV-C emitters can vary depending on the space inside the air treatment unit, the position of UV-C sensitive parts inside the air treatment unit etc.

[0026] The air treatment unit may further comprise a control unit configured to control the irradiation arrangement. The control unit may be an electrical control unit arranged in communication with the irradiation arrangement and the UV-C emitter(s). The control unit may be arranged inside the outer housing of the air treatment unit or externally of the outer housing. In other examples, the control unit is not part of the air treatment unit, but the irradiation arrangement is arranged in communication with an external control unit. The control unit is typically configured to control the irradiation arrangement so that a required or desired level of microorganisms is inactivated, and thus so that the process air provided to the defined space comprises a desired or acceptable number of viable microorganisms. The control unit may also be configured to control the desiccant rotor, the flow of process air entering the air treatment unit etc.

[0027] The control unit may be configured to control the irradiation arrangement by means of controlling at least one of: which UV-C emitter is active, the time an UV-C emitter is active, the number of UV-C emitters that are active at the same time and the power or intensity of the active UV-C emitter(s). This way, the total amount of emitted UV-C light is controlled and the number of viable microorganisms in the process air can be regulated. In the event that the irradiation arrangement comprises a plurality of UV-C emitters, perhaps only one or a few of those should be used at the same time in order to achieve a desired treatment of the process air. For example, if the irradiation arrangement comprises one UV-C emitter upstream of the desiccant rotor and one UV-C emitter downstream of the desiccant rotor, the control unit may control the irradiation arrangement such that only the UV-C emitter upstream of the desiccant rotor is active. The more UV-C emitters that are active at the same time, the more efficient is the sterilization of the process air. Furthermore, the power of the active UV-C emitters will also affect the inactivation rate and higher power will increase the inactivation rate. Thus, the inactivation of viable microorganisms in the process air will depend on the total amount of UV- C light that the process air is exposed to, which in turn will depend on the number of active UV- C emitters, the power of each UV-C emitter and the total time of exposure. The control unit may thus be configured to control the irradiation arrangement by means of controlling the process air's total exposure of UV-C light.

[0028] The control unit may be configured to control the irradiation arrangement based on at least one control parameter, the at least one control parameter comprising humidity of the process air upstream and / or downstream of the desiccant rotor, temperature of the process air upstream of the desiccant rotor, temperature of the process air downstream of the desiccant rotor, flow of process air through the desiccant rotor, the time of the day, the current season, the pathogen level of the process air and / or the rotational speed of the desiccant rotor. In order to achieve an acceptable or desired amount of viable microorganisms in the process air, the irradiation arrangement may have to be controlled in different ways depending on various parameters. Overall, the humidity and the temperature of the process air will affect the inactivation rate provided by the UV-C emitter. Therefore, for example, the humidity and / or temperature of the process air upstream or downstream of the desiccant rotor may determine how to control the irradiation arrangement. As an example, if the temperature of the process air upstream or downstream of the desiccant rotor is below a predetermined threshold value, the control unit may be configured to control the irradiation arrangement so that more UV-C emitters are active, so that the power of the active UV-C emitters is increased and / or so that the UV-C emitters are active a longer time. The flow of process air through the desiccant rotor, and thus the volume and speed of process air, may also affect how to control the irradiation arrangement. A higher volume of process air and / or higher speed of the process air will impact the time it is exposed to the UV-C light. Thus, a higher volume of process air and / or higher speed of the process air will require a greater intensity or power of the active UV-C emitters and / or more active UV-C emitters. The rotational speed of the desiccant rotor may depend on the flow of process air and / or the humidity and / or temperature of the process air. Thus, the irradiation arrangement may be controlled based on the rotational speed of the desiccant rotor. A higher rotational speed of the desiccant rotor may result in the irradiation arrangement being controlled to increase the process air exposure to UV-C light. Similarly, the time of the day and the current season may affect both temperature and humidity of the incoming process air and can be used as control parameters for the irradiation arrangement. For example, the humidity of the outdoor air is normally higher early in the morning. Also, the temperature of the outdoor air is higher during the summer than during winter. Thus, during summer, the irradiation arrangement may be controlled to increase the process air exposure to UV-C light.

[0029] The control unit may further be configured to control the dehumidification of the process air, such as to achieve optimal conditions for the irradiation arrangement. If a specific viable microorganism should be inactivated and inactivation by means of UV-C light is more efficient at a certain relative humidity, the desiccant rotor and / or the flow of process air could be controlled to achieve such relative humidity downstream of the desiccant rotor. Thus, combining control of dehumidification and UV-C light exposure could greatly improve the quality of the process air leaving the air treatment unit.

[0030] Another control parameter may be the current pathogen level of the process air. Pathogens may also be referred to as germs or organisms that can produce diseases. By measuring the number of germs in the process air, the irradiation arrangement can be controlled to emit UV- C light only when required and thereby ensure a healthy environment in the defined space. Also, the current health state in the world may be used as a control parameter for the irradiation arrangement. During a current pandemic, like COVID-19, the irradiation arrangement may be controlled to increase the emitted UV-C light in order to minimize the risk for spreading harmful diseases.

[0031] The air treatment unit may comprise various sensors arranged to measure for example temperature and / or humidity of the process air, the pathogen level of the process air, the rotational speed of the desiccant rotor and / or the flow of process air through the desiccant rotor. The control unit is suitably arranged in communication with such sensors. The control unit may thus be configured to receive data from various sensors in the air treatment unit and based on said data control the irradiation arrangement. The control unit may comprise a database with predetermined threshold values for humidity, temperature etc. The control unit may compare the measured values from the sensors with predetermined threshold values and based on said comparison control the irradiation arrangement to increase or decrease the provided UV-C light. The desiccant rotor may be controlled based on similar or equal parameters as the irradiation arrangement. Thus, the irradiation arrangement may be controlled based on data from already existing sensors in the air treatment unit. Controlling the irradiation arrangement based on the same control parameters as the other components of the air treatment unit will facilitate the control and increase efficiency, and the number of sensors can be reduced. Thus, unlike conventional air treatment units, the present invention integrates at least one UV-C emitter and intelligent control algorithms to provide a highly effective approach in a compact unit for air treatment. It is a strategic and compact incorporation of one or several UV-C emitters, known for its proven ability to eliminate microbial contaminants such as bacteria, viruses, and fungi. This technology enhances the overall performance of the air treatment unit and ensures a more thorough decrease of harmful microorganisms in the treated process air. Complementing the UV-C technology with intelligent sensors will allow continuous monitoring of process air parameters and real-time adjustments by means of the control unit. This ensures optimal energy efficiency while maintaining superior air treatment performance. The energyefficient configuration of the air treatment unit not only minimizes operational costs but also aligns with environmental sustainability goals.

[0032] According to a second aspect of the present disclosure, there is provided a method for controlling an air treatment unit according to the first aspect, wherein the method comprises the step of controlling the irradiation arrangement to reduce the number of viable microorganisms in the process air. As described above, the control of the irradiation arrangement is performed by a control unit, for example the control unit of the air treatment unit. The method is thus performed by a control unit. It is to be understood that all features and advantages mentioned with regard to the first aspect of the present disclosure, are also applicable on the second aspect of the present disclosure.

[0033] The step of controlling the irradiation arrangement may comprise at least one of controlling which UV-C emitter is active, the time an UV-C emitter is active, the number of UV-C emitters that are active at the same time and / or the power of the active UV-C emitter.

[0034] The step of controlling the irradiation arrangement may be performed based on at least one control parameter, the at least one control parameter the method comprising humidity of the process air upstream and / or downstream of the desiccant rotor, temperature of the process air upstream of the desiccant rotor, temperature of the process air downstream of the desiccant rotor, flow of process air through the desiccant rotor, the time of the day, the current season, the pathogen level of the process air and / or the rotational speed of the desiccant rotor.

[0035] According to an aspect of the present disclosure, a computer program for an air treatment unit is also provided. The air treatment unit may be configured as disclosed herein. The control unit configured to control the irradiation arrangement of the air treatment comprises at least one processor, the computer program comprising computer-readable instructions which, when executed by the at least one processor, causes the control unit to carry out the steps of the method as disclosed herein.

[0036] Furthermore, according to an aspect of the present disclosure there is provided a computer program product comprising at least one computer-readable medium, such as a non-transitory memory, storing the above-mentioned computer program.

[0037] The present disclosure will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the disclosure by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the disclosure.

[0038] Hence, it is to be understood that the herein disclosed disclosure is not limited to the particular component parts of the device described or steps of the methods described since such device and method may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings do not exclude other elements or steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above objects, as well as additional objects, features and advantages of the present disclosure will be more fully appreciated by reference to the following illustrative and nonlimiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.

[0040] Figure 1A schematically illustrates an air treatment unit according to an example of the present disclosure;

[0041] Figure IB schematically illustrates a control unit according to an example of the present disclosure;

[0042] Figure 2 schematically illustrates an air treatment unit according to an example of the present disclosure;

[0043] Figure 3 schematically illustrates an air treatment unit according to an example of the present disclosure;

[0044] Figure 4A-B schematically illustrate an air treatment unit according to examples of the present disclosure; and

[0045] Figure 5 schematically illustrates a method for controlling an air treatment unit according to an example of the present disclosure.

[0046] DETAILED DESCRIPTION

[0047] Figure 1A schematically illustrates an air treatment unit 1 for providing treated air in a defined space S according to an example of the present disclosure. The air treatment unit 1 comprises a desiccant rotor 100; a process air circuit 11 arranged to conduct process air 110 through a process section 111 of the desiccant rotor 100; and a regeneration air circuit 12 arranged to conduct regeneration air 120 through a regeneration section 121 of the desiccant rotor 100. As shown in the figure, the process air 110 is outdoor air OA entering the air treatment unit 1. The process air 110 is conducted through the process section 111 of the desiccant rotor 100 and is discharged in the defined space S. The regeneration air 120 may come from the defined space S and is conducted through the regeneration section 121 of the desiccant rotor 100 before being discharged outdoors. The desiccant rotor 100 is configured to rotate about a rotational axis with a variable rotational speed.

[0048] The air treatment unit 1 further comprises a controllable irradiation arrangement 13 comprising at least one integrated UV-C emitter 130 arranged to, when active, emit UV-C light to reduce the amount of viable microorganisms in the process air 110. The at least one UV-C emitter 130 is thus arranged in association with the process air 110. This way, the process air 110 will be exposed to UV-C light, which will kill or inactivate certain microorganisms in the process air 110. The process air 110 will thereby comprise a reduced amount of viable microorganisms.

[0049] The irradiation arrangement 13 is controlled by a control unit 16. The control unit 16 may form part of the air treatment unit 1 or it may be an external control unit. The control unit 16 may be configured to control which UV-C emitter 130 is active, the time (how long) an UV-C emitter 130 is active, the number of UV-C emitters 130 that are active at the same time and / or the power of the active UV-C emitter(s) 130. This way, the control unit 16 is configured to control how much UV-C light the process air 110 is exposed to.

[0050] The control unit 16 may further be configured to control the irradiation arrangement 13 based on at least one control parameter, the at least one control parameter comprising humidity of the process air 110 upstream of the desiccant rotor 100, temperature of the process air 110 upstream of the desiccant rotor 100, temperature of the process air 110 downstream of the desiccant rotor 100, flow of process air 110 through the desiccant rotor 100, the time of the day, the current season, the pathogen level of the process air 110 and / or the rotational speed of the desiccant rotor 100. The control unit 16 may be configured to control the irradiation arrangement 13 based on the same parameters as the desiccant rotor 100 is controlled.

[0051] Figure IB illustrates an exemplary embodiment of a control unit 16 of an air treatment system 1 according to the present disclosure. The control unit 16 may form part of an air treatment system 1 as disclosed in Figure 1A. The control unit 16 comprises at least one processor 601 and a storage medium 602. The control unit 16 may be configured to perform the method as described in Figure 5 upon execution of a computer program by the at least one processor 601. The computer program(s) comprise computer-readable instructions that may be stored in the storage medium 602, such as a non-transitory hardware memory device of the control unit 16.

[0052] Figure 2 schematically illustrates an air treatment unit 1 for providing treated air in a defined space S according to an example of the present disclosure. The air treatment unit 1 may be configured as disclosed in Figure 1A. In this example, the irradiation arrangement 13 comprises two UV-C emitters 130, one arranged upstream of the desiccant rotor 100 and one downstream of the desiccant rotor 100.

[0053] Figure 3 schematically illustrates an air treatment unit 1 for providing treated air in a defined space S according to an example of the present disclosure. The air treatment unit 1 may be configured as disclosed in Figure 1A. In this example, the air treatment unit 1 comprises a fan 17 arranged upstream of the desiccant rotor 100. The irradiation arrangement 13 comprises at least three UV-C emitters 130, one arranged upstream of the fan 17, one arranged between the fan 17 and the desiccant rotor 100 and one downstream of the desiccant rotor 100.

[0054] Figure 4A-B schematically illustrate an air treatment unit 1 according to two examples of the present disclosure. The air treatment unit 1 may be configured as disclosed in Figure 1A, 2, or 3. Figure 4A shows the air treatment unit 1 comprising an outer housing 2 surrounding and enclosing the desiccant rotor 100, the process air circuit 11, the regeneration air circuit 12 and the irradiation arrangement 13. The air treatment unit 1 also comprises a protective coating 140 on at least a part of the air treatment unit 1 to protect the air treatment unit l from the emitted UV-C light. Furthermore, the air treatment unit 1 comprises a reflective element 15 arranged to reflect the emitted UV-C light and thereby increase the exposure of UV-C light. In the example shown in Figure 4B, the protective coating 140 and the reflective element 15 are integrated and the air treatment unit 1 thus comprises a protective and reflective coating on the inside of the air treatment unit 1.

[0055] Figure 5 schematically illustrates a method for controlling an air treatment unit 1 according to an example of the present disclosure. The air treatment unit 1 may be configured as in any of the preceding figures. The method comprises the step of controlling s201 the irradiation arrangement 13 to reduce the amount of viable microorganisms in the process air 110. The method is suitably performed by the control unit 16. The step of controlling s201 the irradiation arrangement 13 may comprise controlling which UV- C emitter 130 is active, the time an UV-C emitter 130 is active, the number of UV-C emitters 130 that are active at the same time and / or the power of the active UV-C emitter(s) 130.

[0056] The step of controlling s201 the irradiation arrangement 13 may be performed based on at least one control parameter comprising humidity of the process air 110 upstream of the desiccant rotor 100, temperature of the process air 110 upstream of the desiccant rotor 100, temperature of the process air 110 downstream of the desiccant rotor 100, flow of process air 110 through the desiccant rotor 100, the time of the day, the current season, the pathogen level of the process air 110 and / or the rotational speed of the desiccant rotor 100. The control parameters may be determined by means of sensors measuring said parameters and sending the measured values to the control unit 16. The control unit 16 may compare said measured values with predetermined threshold values and based on the comparison determine if the process air 110 should be exposed to more or less UV-C light and control the irradiation arrangement 13 accordingly.

[0057] The step of controlling s201 the irradiation arrangement 13 may thus comprise determining the humidity of the process air 110 upstream of the desiccant rotor 100, the temperature of the process air 110 upstream of the desiccant rotor 100, the temperature of the process air 110 downstream of the desiccant rotor 100, the flow of process air 110 through the desiccant rotor 100, the time of the day, the current season, the pathogen level of the process air 110 and / or the rotational speed of the desiccant rotor 100 and based on that control which UV-C emitter 130 is active, the time each UV-C emitter 130 is active, the number of UV-C emitters 130 that are active at the same time and / or the power of the active UV-C emitter(s) 130.

Claims

CLAIMS1. An air treatment unit (1) for providing treated air in a defined space (S), the air treatment unit (1) comprising;- a desiccant rotor (100);- a process air circuit (11) arranged to conduct process air (110) through a process section (111) of the desiccant rotor (100);- a regeneration air circuit (12) arranged to conduct regeneration air (120) through a regeneration section (121) of the desiccant rotor (100); wherein the air treatment unit (1) further comprises:- a controllable irradiation arrangement (13) comprising at least one integrated UV- C emitter (130) arranged to, when active, emit UV-C light to reduce the amount of viable microorganisms in the process air (110).

2. The air treatment unit (1) according to claim 1, wherein at least a part of the air treatment unit (1) comprises a protective coating (140) configured to protect the air treatment unit (1) from the UV-C light (2) emitted by the at least one UV-C emitter (130).

3. The air treatment unit (1) according to claim 1 or 2, wherein the air treatment unit (1) further comprises;- a reflective element (15) arranged in association with the at least one UV-C emitter (130).

4. The air treatment unit (1) according to claim 2 and 3, wherein the protective coating (140) and the reflective element (15) are integrated with each other.

5. The air treatment unit (1) according to any one of the preceding claims, wherein the irradiation arrangement (13) comprises at least one UV- C emitter (130) arranged upstream of the desiccant rotor (100).

6. The air treatment unit (1) according to any one of the preceding claims, wherein the irradiation arrangement (13) comprises at least one UV-C emitter (130) arranged downstream of the desiccant rotor (100).

7. The air treatment unit (1) according to any one of the preceding claims, wherein the at least one UV-C emitter (130) is a FAR-UVC emitter (133).

8. The air treatment unit (1) according to any one of the preceding claims, further comprising;- a control unit (16) configured to control the irradiation arrangement (13).

9. The air treatment unit (1) according to claim 8, wherein the control unit (16) is configured to control the irradiation arrangement (13) by means of controlling at least one of: which UV-C emitter (130) is active, the time an UV-C emitter is active, the number of UV-C emitters (130) that are active at the same time and the power of the active UV-C emitter(s) (130).

10. The air treatment unit (1) according to claim 8 or 9, wherein the control unit (16) is configured to control the irradiation arrangement (13) based on at least one control parameter, the at least one control parameter comprising humidity of the process air (110) upstream and / or downstream of the desiccant rotor (100), temperature of the process air (110) upstream of the desiccant rotor (100), temperature of the process air (110) downstream of the desiccant rotor (100), flow of process air (110) through the desiccant rotor (100), the time of the day, the current season, the pathogen level of the process air (110) and / or the rotational speed of the desiccant rotor (100).

11. A method for controlling an air treatment unit (1) according to any one of claims 1-10, wherein the method comprises the step of:- controlling (s201) the irradiation arrangement (13) to reduce the amount of viable microorganisms in the process air (110).

12. The method according to claim 11, wherein the step of controlling (s201) the irradiation arrangement (13) comprises at least one of: controlling which UV-C emitter (130) is active, the time an UV-C emitter is active, the number of UV-C emitters (130) that are active at the same time and / or the power of the active UV-C emitter(s) (130).

13. The method according to claim 11 or 12, wherein the step of controlling (s201) the irradiation arrangement (13) is performed based on at least one control parameter, the at least one control parameter comprising humidity of the process air (110) upstream and / or downstream of the desiccant rotor (100), temperature of the process air (110) upstream of the desiccant rotor (100), temperature of the process air (110) downstream of the desiccant rotor (100), flow of process air (110) through the desiccant rotor (100), the time of the day, the current season, the pathogen level of the process air (110) and / or the rotational speed of the desiccant rotor (100).

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