Heat-based technology for risk mitigation of pathogenic infection in heating, ventilation, and air conditioning systems

Abstract

A filtration device for use in an air duct system, the device including at least two side-by-side sealable enclosure units positioned generally perpendicular to airflow within an air duct; one or more filters in each of the at least two side-by-side sealable enclosure units; a heating element; and a set of isolation gate pairs for each of the at least two side-by-side sealable enclosure units. Each isolation gate of the pair is positioned on opposing sides of the enclosure unit. Pairs of the set of isolation gate pairs are open when the heating element is off in the corresponding enclosure unit, and conversely the pairs of the set of isolation gate pairs are closed when the heating element is on in the corresponding enclosure unit. The filtration device is configured to disinfecting an air supply by entrapping pathogens from the air on one or more filters.

Description

HEAT-BASED TECHNOLOGY FOR RISK MITIGATION OF PATHOGENIC INFECTION IN HEATING, VENTILATION, AND AIR CONDITIONING SYSTEMSRELATED APPLICATIONS

[0001] This application claims priority benefit of US Provisional Application Serial Number 63 / 541,338 filed 29 September 2023; the contents of which are hereby incorporated by reference.FIELD OF THE INVENTION

[0002] The present invention relates, in general, to heating, ventilation, and air conditioning (HVAC) systems and, in particular, to a system and method for air disinfection and mitigation of pathogenic agents in enclosed environments.BACKGROUND OF THE INVENTION

[0003] The recent SARS-CoV-2 (A.K.A. Covid-19) pandemic has placed a renewed emphasis on indoor air quality and mitigation of pathogenic agents by building environmental systems. Several sterilization methods, such as ultraviolet germicidal irradiation (UVGI), photocatalytic oxidation (PCO), and Plasma cluster ions, are commercially available to inactivate various infectious agents. The most well-known sterilization method in the indoor environmental control industry is the use of ultraviolet light (UV) for disinfection treatment. Ultraviolet light, at germicidal wavelengths, alters the genetic (DNA) material in cells so that viruses and other microorganisms can no longer reproduce. However, there are many difficulties and limitations related to the installation and maintenance of UV lights. UV light only works in a defined light path, and a UV light path can be blocked by objects and exposure to UV light may have adverse health effects on the skin (erythema) and eyes (photokeratitis). In addition, UV light application for air disinfection is a costly method with less-than-idealpathogen deactivation kinetics. Other existing methods of air disinfection also have similar limitations and are costly. The advantages and disadvantages of existing engineering techniques for lowering the pathogen concentration in HVAC systems are summarized in Table 1.

[0004] Table 1: Existing Disinfection Technologies

[0005] While there are existing disinfection techniques for HVAC systems, as is shown in Table 1, these existing disinfection systems and methods also have serious disadvantages with regard to reliability, effectiveness over time, costs, maintenance requirements, potential adverse health effects, and generation of harmful by-products that may be released to the environment.

[0006] Thus, there exists a need for improved systems and methods for air disinfection and mitigation of pathogenic agents in enclosed environments that provide increased reliability and effectiveness over time and lower costs and maintenance requirements while preventing potential adverse health effects and the generation of harmful by-products that may be released to the environment.SUMMARY OF THE INTENTION

[0007] The present invention provides a filtration device for use in an air duct system. The device includes at least two side-by-side sealable enclosure units positioned generally perpendicular to airflow within an air duct; one or more filters in each of the at least two side- by-side sealable enclosure units; a heating element; and a set of isolation gate pairs for each of the at least two side-by-side sealable enclosure units. Each isolation gate of the pair is positioned on opposing sides of the enclosure unit. Pairs of the set of isolation gate pairs are open when the heating element is off in the corresponding enclosure unit, and conversely the pairs of the set of isolation gate pairs are closed when the heating element is on in the corresponding enclosure unit.

[0008] The present invention additionally provides a method of disinfecting an air supply that includes drawing air into an HVAC system including an inventive filtration device; entrapping pathogens from the air on one or more filters in line with the airflow to create acontaminated filter; isolating the contaminated filter from the airflow and heating the contaminated filter outside of the airflow to deactivate the pathogens.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0010] FIG. 1A is a schematic perspective view of two side-by-side units for air disinfection and mitigation of pathogenic agents, each unit having a filter, a heating element, and a sealed enclosure in accordance with embodiments of the invention;

[0011] FIG. IB is a top view of the two side-by-side units of FIG. 1A;

[0012] FIG. 1C is a timing diagram of sequential entrapment and disinfection using combined filtration and heat in accordance with embodiments of the invention;

[0013] FIG. 2 is an overall system view of the filtration units installed in a heating, ventilation, and air conditioning (HVAC) system in accordance with embodiments of the invention;

[0014] FIGS. 3A-3C are schematic diagrams of enclosure configurations with a single heating element in accordance with embodiments of the invention;

[0015] FIGS. 4A-4C are schematic diagrams of enclosure configurations with multiple heating elements in accordance with embodiments of the invention;

[0016] FIGS. 5A-5C are schematic diagrams of enclosure configurations with multiple fixed heating elements in accordance with embodiments of the invention;

[0017] FIG. 6 is a perspective view of an embodiment of the filtration system inside an air duct in accordance with embodiments of the invention;

[0018] FIG. 7 is an exploded view of an embodiment of the filtration system, showing the major components in accordance with embodiments of the invention;

[0019] FIG. 8 is a perspective view of an embodiment of the filtration system with outer covers removed in accordance with embodiments of the invention;

[0020] FIG. 9 is a photograph of an actual filtration system in accordance with embodiments of the invention;

[0021] FIG. 10 is a front view of an embodiment of a heating element designed for use with embodiments of the invention; and

[0022] FIG. 11 is perspective view of another embodiment in which heating elements are provide outside the enclosure with a series of fans to circulate heated air within the enclosure.DESCRIPTION OF THE INVENTION

[0023] The present invention has utility as an improved system and method for air disinfection and mitigation of pathogenic agents in enclosed environments that provides increased reliability and effectiveness over time and lowers costs and maintenance requirements while preventing potential adverse health effects and the generation of harmful by-products that may be released to the environment. In the context of the present invention, enclosed environments, illustratively, include buildings, transportation vehicles, and spaceships.

[0024] Embodiments of the present invention provide solutions that overcome limitations in the existing indoor air treatment and environmental technologies and provide a cost-effective and easily implementable HVAC solution that provides clean indoor air for various types of enclosed environments.

[0025] Embodiments of the invention disinfect the air by application of heat to the fdter. While thermal inactivation of microorganisms by heat has been widely used for the inactivationof infectious agents in “non-aerosol” applications, currently, there are no technologies available that use heat to inactivate pathogens in HVAC systems. In the past, in indoor air treatment applications, heat has not been used due to high energy requirements. Furthermore, heat has not been used in the HVAC context to avoid excess thermal loading in the HVAC system. Adding heat for air disinfection, then cooling it down to the desired temperature in an openpass HVAC system, has proven to be costly.

[0026] Embodiments of the invention overcome this deficiency by utilizing heat effectively to disinfect a filter and destroy the entrapped microorganisms, as most of the microorganisms are inactivated when exposed to sustained heat at a temperature of 60±10°C for a predefined period of time in an insulated enclosure. Embodiments of the inventive design provide an integrated filtering unit that relies on minimal heat addition and operational cost while allowing continuous ventilation with clean air. As the inactivation of microorganisms in embodiments of the invention occurs in an insulated enclosure containing the filter, the process is cost- effective, safe, and environment-friendly for purifying air contaminated with bioaerosol particles in HVAC systems.

[0027] Embodiments of the present invention provide an innovative technology to entrap and thereafter destroy pathogens suspended in the air in ventilated buildings and other enclosed environments with air handling. Several infectious pathogens, such as SARS-CoV-2 and influenza viruses, may travel in an HVAC system while encapsulated in minute droplets. All HVAC filters entrap and accumulate microorganisms to the extent that depends on the filter efficiency and filter replacement frequency. Accumulation of microbes in the filter can turn the filter into a breeding ground for fungi and bacteria, making the filter a biologically hazardous object. In addition, filter disposal may become hazardous unless a safe disposal protocol is followed to minimize the risks. Furthermore, any change or disturbance in the airflow may dislodge entrapped microorganisms back into the environment. Embodiments of the presentinvention avoid many of these issues with a compact and economical device that entraps microorganisms in the HVAC fdters and then inactivates the microorganisms with a resort to heating.

[0028] As used herein, a “filter” is defined as a woven or non-woven material formed from cellulosic, fiberglass, sintered ceramics, metal mesh, or a combination thereof and having sufficient porosity to allow force air flow through, entrapping a wide range of particles including dust, pet dander, and microbes.

[0029] In embodiments of the present invention, two or more side-by-side disinfection units are integrated with heating elements and air filters. Each side-by-side disinfection unit disinfects its own self-contained filter in a closed system and in sequential operation between the side-by-side disinfection units, relying on minimal heating and low operational cost while allowing continuous ventilation with clean air. Embodiments of the present invention can benefit a variety of ventilated structures. These structures illustratively include residential buildings, commercial buildings, hospitals, clinics, clean rooms, surgical suites, and care facilities, as well as transportation vehicles that illustratively include passenger vehicles, rail cars, ships, and aircraft. Embodiments of the present invention eliminate the microbes effectively, can easily be installed in existing and new HVAC systems, and are more efficient and economical than existing technologies that rely on UV light and other technologies for pathogen deactivation.

[0030] The present invention will now be described with reference to the following embodiments. As is apparent by these descriptions, this invention can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. For example, features illustrated with respect to one embodiment can be incorporated into other embodiments, and featuresillustrated with respect to a particular embodiment may be deleted from the embodiment. In addition, numerous variations and additions to the embodiments suggested herein will be apparent to those skilled in the art in light of the instant disclosure, which does not depart from the instant invention. Hence, the following specification is intended to illustrate some particular embodiments of the invention and not to exhaustively specify all permutations, combinations, and variations thereof.

[0031] It is to be understood that in instances where a range of values is provided, the range is intended to encompass not only the endpoint values of the range but also intermediate values of the range as explicitly being included within the range and varying by the last significant figure of the range. By way of example, a recited range of from 1 to 4 is intended to include 1- 2, 1-3, 2-4, 3-4, and 1-4.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting to the invention.

[0033] Unless indicated otherwise, explicitly or by context, the following terms are used herein as set forth below.

[0034] As used in the description of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well unless the context clearly indicates otherwise.

[0035] Also, as used herein, “and / or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (“or”).

[0036] Referring now to the figures, FIGS. 1A and IB show the inventive filtration device 10 positioned in an air duct 12 (shown in ghost), including at least two side-by-side sealed enclosure units 14A and 14B, each of the two side-by-side units having a fdter (16A, 16B), a heating element (18A, 18B), and a set of isolation gates (20A, 20B). As shown in FIG. IB, when the heating element 18A is off, the isolation gates 20A are open in order to allow airflow to enter fdter 16A to entrap particulate in the fdter 16A of enclosure unit 14A. Conversely, when one unit (unit 14B as shown) is inactivating the pathogens in fdter 16B, the isolation gates 20B are closed to contain the heat generated by the tumed-on heating element 18B to sterilize the fdter 16B. Therefore, the two side-by-side units (14A, 14B) alternate between entrapping particulate and inactivating pathogens. Initiady, both side-by-side units’ (14A, 14B) isolation gates (20A, 20B) are opened to start the fdtering function, and at least heating elements (18A, 18B) are turned off. FIG. 1C is a timing diagram which illustrates after a defined period of time time, one of the units (14A, 14B) is isolated by closing its gates and turning on its heating element to disinfect the unit, while the other unit has the gates open in order to entrap particulate. As shown in FIG. 1C, the two units (14A, 14B) alternate disinfection and entrapment and eliminate the codected microbes in the fdters (16A, 16B) sequentially. It is further noted that the amount of heat required to disinfect the fdter media is minimized, as the heating is performed in an insulated enclosure with the gates closed to retain and concentrate the applied heat for the particular unit. It is appreciated that a larger number of fdters and units than the two depicted would be well-suited for larger HVAC units in which larger volumes of air are processed.

[0037] According to the World Health Organization (WHO), heat at 56 °C kills the SARS coronavirus at around 10,000 units in 15 min [World Health Organization (web page), First Data on Stability and Resistance of SARS Coronavirus Compiled by Members of WHOLaboratory Network, Technical guidance, Laboratory], Similarly, according to Wang et al., thenucleo-capsid protein of SARS-CoV is completely denatured in 10 min at 55°C [Wang Y., Wu X., Wang Y., Li B., Zhou H., Yuan G., Fu Y., Luo Y., Low Stability of Nucleo-Capsid Protein in SARS Virus, Biochem., 2004; 43:11103-11108], Some of the most transmittable viruses, such as influenzas and the common cold, as well as other pathogens such as vegetative bacteria, chickenpox, measles, mumps, pertussis, tuberculosis, and diphtheria may also be transmitted through the ventilation system [Tang J.W., Li Y., Eames L, Chan P.K., Ridgway G.L., Factors Involved in the Aerosol Transmission of Infection and Control of Ventilation in Healthcare Premises, J. Hosp. Infect., 2006; 64(2): 100-14] and can be inactivated by heat. Therefore, the duration of time that heating elements are turned on is determined based on the targeted pathogens that require deactivation, and the temperature is raised to the corresponding required levels and maintained for a specified period to ensure adequate disinfection.

[0038] Temperature setting control is based on sensor signals from points adjacent to the heating element to control the maximum operating temperature of the filter and at the location expected to be the coldest point in the enclosure to ensure its temperature is raised above the required minimum temperature for disinfection. An automatic or programmable temperature controller / thermostat may be used to control the temperature and duration of entrapment and disinfection periods of each unit based on the measured temperature as a process variable and that of the desired / set value of temperature within the disinfection unit.

[0039] Embodiments of the inventive filtration device design and placement may vary depending on the size and design of the HVAC system in which the filtration device is implemented. As shown in FIG. 2, a single filtration device 10, or a plurality of such devices 10, may be installed at the end of the return air duct before the ventilation unit before or after the outdoor air intake. Even though installing the disinfection unit after the outdoor air intake is safer as the filter can entrap pathogens from the outdoor air intake, in some embodiments, this reduces the filter life cycle and requires quicker filter replacement due to pollution withinthe outdoor air. For larger buildings and open spaces, several filtration devices may be installed at proper positions in the system or for each individual room / open space. The central ventilation system can then safely supply air to all individual rooms by mixing the outdoor and recirculated air.

[0040] In specific embodiments of the inventive filtration device 10, the outer layer of the enclosure (14A, 14B), as well as the isolation gates (20A, 20B), may be made of materials with low thermal conductivity, high fluidity during mouldings, high heat tolerance, dimensional stability, and high stiffness. Examples of such materials illustratively include high-temperature thermosetting and thermoplastic materials to provide long-term service temperature appropriate for this application, such as Bakelite (polyoxybenzylmethyleneglycolanhydride) PEEK (polyaryletherketone), Polyimide (PI), and liquid crystal polymer. Bakelite with a thermal conductivity of 0.2 W / (m K), a heat capacity of 0.92 kJ / (kg K) and a maximum working temperature of 120 °C, which is produced in many commercial grades to meet diverse mechanical, electrical and thermal requirements is a good candidate for this application. It should be noted that a combination of materials, including metals, ceramics and plastics in solid and hollow forms, may be used to provide enough mechanical strength and thermal requirements for the enclosure body and doors.

[0041] Different configurations of the filtration device 10 may be implemented. In an embodiment, a single heating element and a single air filter are available per disinfection unit. As shown in FIG. 3A the heating element may be attached to one of the gates (at the entry or exit side of the disinfection unit) and moved. The gates are hinged to the enclosure and rotated together for opening or closing the enclosure. With the configuration of FIG. 3 A it is necessary that there is sufficient space in the duct to allow for complete opening of the gates. In addition, this may require a large rotating torque / energy and generally causes considerable disturbance to airflow when opening or closing the gates, which may cause some trapped particles to bereleased randomly and unpredictably from the fdter surfaces. In FIG. 3B the heating element is attached to the gate, and the gate is retracted to allow airflow for entrapment in the fdter. The configuration of FIG. 3B requires more space at two sides of the air duct to allow retraction of the gates and the attached heating elements. If there is enough room in the air duct for retraction, this configuration causes the least disturbance to airflow and requires less moving / sliding power to move the gates. In FIG. 3C, and as also shown in FIGS. 1A and IB, the heating element is fixed inside the unit, and multiple gates are opened or closed by rotating along one or several hinges. The use of multiple gates minimizes air disturbance and provides a compact filtration device, making it suitable for installation in a limited space.

[0042] In an embodiment, multiple heating elements and / or multiple air filters could be enclosed in a filtration device. Filter media is the means to entrap microorganisms or particles contaminated with microorganisms. Reduction in the amount of such particles depends on the pore size of the filter, the amount of the particles, their size, and the charge of the particles. In installations such as a healthcare facility that require the maintenance of a safe and high air quality environment, a high-efficiency particulate air (HEP A) filter or several filters as a filter bank within each filtration unit may be used. High-efficiency filters are capable of particulate matter removal in the range of coronavirus.

[0043] Several considerations come into play when selecting air filters for the filtration device. In addition to space availability, filtration performance requirements and air-moving (cfm) requirements, here also, the resistance of the filter to heat transfer is also an important parameter to be considered. Increasing the air filtration efficiencies typically results in higher pressure drops. Currently, there are air filtration products such as pleated air filters that are manufactured with high efficiencies and little or negligible increase in pressure drop. Such filters allow more filter surface area, thus reducing airflow resistance. In general, thin filters are expected to present the least heat transfer resistance. For this application, the highest MERVnumber and lowest resistance to heat transfer air filter should be considered, providing the airflow pressure drop is not increased beyond the point of system design capabilities of the HVAC system.

[0044] In order to advance heat transfer within multiple fdters, multiple heating elements are provided depending on enclosure configurations as follows. In FIG. 4A heating elements are attached to both gates at the entry and exit side, and the heating elements are moved. In FIG. 4B heating Elements are attached to the gates at the entry and exit side and are retracted. In FIG. 4C with multiple filter / filter banks, an additional heating element is provided to improve heat transfer. In an embodiment, several heating elements are fixed inside the unit at different locations with respect to the filters, and the gates are opened or closed by rotating along one or several hinges, as shown in FIGS. 5A-5C.

[0045] In embodiments of the filtration device, different mechanisms may be used for opening and closing the gates. It should be noted that the appropriate mechanism should provide reliable and durable performance, smooth operation from opening to closing, as well as a good seal when the gates are closed. An example of the operating mechanism for multiple gates is shown in FIGS 6 and 7. In the embodiment shown with multiple gates 20, the opening and closing mechanism is a set of electric linear actuators 22 that actuate a corresponding set of sliders and connecting rods 24 that support and move gates 20. This provides the opening and closing of all the gates at both sides of each of the side-by-side enclosures by a single actuator. Linear actuator 22A controls sliders and connecting rods 24A that support and move gates 20A for enclosure 14A, while linear actuator 22B controls sliders and connecting rods 24B that support and move gates 20B for enclosure 14B so as to ensure a proper seal of the gates (20A, 20B) when the corresponding heating element (18A, 18B) is on for energy saving. Electrical connection 26 provides power to the linear actuators (22A, 22B) and heating elements (18A, 18B). FIG. 7 shows an exploded view of enclosure 14 with a frame 28 with aslot 30 for a filter 16 and a fitting to support and hold the heating element 18 as well as the linear actuator 22 and sliders and connecting rods 24. FIG. 8 is a perspective view of an embodiment 10’ of the filtration device. FIG. 9 is a photo of an actual filtration system 10”.

[0046] FIG. 10 is a front view of an embodiment of a heating element 18’. The heating element converts electrical energy into thermal energy to heat the enclosure 14. In addition to the general requirement of a good heating element, the heating conductor 32 should have sufficient mechanical strength and be made of anti-corrosive materials while providing rapid heating and uniform temperature distribution along its length and within the filter media. Furthermore, the heating conductor 32 should be as thin as possible to save space and cause less resistance to airflow. As shown in FIG. 10, the heating conductor 32 may be welded to metal mesh 34 with high thermal conductivity and corrosion resistance for more effective and uniform heat transfer to the filter media. Such configuration provides support and sufficient surface contact with the installed filter to improve heat transfer to filter media. The optimum configuration of the heating element configuration provides the least resistance to airflow and uniform heat transfer to filter media.Other Embodiments

[0047] While the method of heating the filter as disclosed herein is the use of an electrical heating element, it is appreciated that heating is not limited to electrical heating but may also include any heating source such as hot air injection, infrared lights, and hot water coil may be used to heat the enclosure content to the prescribed temperature and time to inactivate microorganisms. Further, while the heating components depicted in FIG. 10 are distinct from the filter, they have the potential to be incorporated within the filter's fabric. Furthermore, while the prototypes depicted in FIGS. 9 and 10 show the heating elements inside the enclosure to heat up the filter by natural convection, heating elements could alternatively be implemented outside the enclosure, accompanied by a series of fans to circulate heated air within theenclosure (FIG. 11). In this configuration, air is entered from a slot at the bottom of each unit and exits from the top sides and two ducts at each side connect the top sides of the units to the heat chambers at the bottom. Such configurations that use forced convection heat transfer may provide a more uniform temperature distribution within the units and consequently the filters. The heated air circulation configuration is not limited to what is depicted in FIG. 11, and other configurations are possible.

[0048] In addition to side-by-side arrangement, the disinfection units may be arranged in different orders. Each unit containing the gates, the heating element and the filter, may be located inside or outside the ductwork. The gates, the heating element or the filter, may be moved inward or outward of the enclosure to make entrapment or disinfection processes possible.

[0049] While electrical linear actuators are shown, it is appreciated that any mechanism, such as electromechanical, pneumatic, or hydraulic systems, may provide opening and closing of the disinfection unit.

[0050] Patent documents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These documents and publications are incorporated herein by reference to the same extent as if each individual document or publication was specifically and individually incorporated herein by reference.

[0051] The foregoing description is illustrative of particular embodiments of the invention but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.

Claims

CLAIMS1. A filtration device for use in an air duct system, the device comprises: at least two side-by-side sealable enclosure units positioned generally perpendicular to airflow within an air duct; one or more filters in each of the at least two side-by-side sealable enclosure units; a heating element; and a set of isolation gate pairs for each of the at least two side-by-side sealable enclosure units, where each isolation gate of the pair is positioned on opposing sides of the enclosure unit, where pairs of the set of isolation gate pairs are open when the heating element is off in the corresponding enclosure unit, and conversely the pairs of the set of isolation gate pairs are closed when the heating element is on in the corresponding enclosure unit.

2. The device of claim 1, wherein an outer layer of at least two side-by-side sealable enclosure units as well as the sets of isolation gates are made of materials with low thermal conductivity, low heat capacity, high fluidity during mouldings, high heat tolerance, dimensional stability, and high stiffness.

3. The device of claim 2 wherein said materials contains one or more of Bakelite (polyoxybenzylmethyleneglycolanhydride), PEEK (polyaryletherketone), Polyimide (PI), and liquid crystal polymer.

4. The device of claim 1 wherein each of the at least two side-by-side sealable enclosure units is configured with a single heating element and a single air filter.

5. The device of claim 4 wherein the single heating element of each of the at least two side-by-side sealable enclosure units is attached to one gate of the set of isolation gate pairs and wherein the one gate is an entry gate for the airflow or an exit gate for the airflow.

6. The device of claim 5 wherein the isolation gate pairs are hinged to each of the at least two side-by-side sealable enclosure units, and the isolation gate pairs are rotated together for opening or closing each of the enclosures.

7. The device of claim 5 wherein the isolation gate pairs are retractable and move parallel with respect to each of the at least two side-by-side sealable enclosure units.

8. The device of claim 4 wherein the single heating element is fixed inside each of the at least two side-by-side sealable enclosure units, and each gate of the set of isolation gate pairs is made up of multiple gates, where the multiple gates are opened or closed by rotation along one or several hinges.

9. The device of claim 1 wherein each of the at least two side-by-side sealable enclosure units is configured with at least two heating elements and a plurality of air filters.

10. The device of claim 9 wherein at least two heating elements are separately attached to one gate of the set of isolation gate pairs and wherein the one gate is an entry gate for the airflow or an exit gate for the airflow.

11. The device of claim 10 wherein the isolation gate pairs are hinged to each of the two side-by-side sealable enclosure units, and the isolation gate pairs are rotated together for opening or closing each of the enclosures.

12. The device of claim 10 wherein the isolation gate pairs are retractable and move parallel with respect to each of the two side-by-side sealable enclosure units.

13. The device of any one of claims 1 to 12 wherein the set of isolation gate pairs is actuated with one or more linear actuators.

14. The device of any one of claims 1 to 12 wherein each gate of the set of isolation gate pairs is made up of multiple gates, where the multiple gates are connected to sets of sliders and connecting rods that are actuated with one or more linear actuators.

15. The device of any one of claims 1 to 12 wherein the heating element comprises a heating conductor welded to a mesh.

16. The device of any one of claims 1 to 12 wherein the one or more filters are of any kind air filters including high-efficiency particulate air (HEP A) filters.

17. The device of any one of claims 1 to 12 wherein temperature setting control of the heating elements is based on sensor signals from points adjacent to the heating element to control the maximum operating temperature of the filter and at a location expected to be the coldest point in the sealable enclosure unit to ensure a temperature inside the sealable enclosureunit is raised above the required minimum temperature for disinfection of the fdter based on targeted pathogens entrapped in the filter.

18. The device of any one of claims 1 to 12 further comprises an automatic or programmable temperature controller / thermostat that is used to control a temperature and a duration of entrapment and disinfection periods for each of the sealable enclosure units based on a measured temperature as a process variable and that of a desired / set value of temperature within the sealable enclosure unit.

19. A method of disinfecting an air supply comprising: drawing air into an HVAC system of claim 1; entrapping pathogens from the air on one or more fdters in line with the airflow to create a contaminated fdter; isolating the contaminated filter from the airflow and heating the contaminated filter outside of the airflow to deactivate the pathogens.

20. The method of claim 19 wherein a second filter of the one or more filters is retained in the airflow during the isolating and the heating.

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