Air flow sterlization method and air sterlization device

Abstract

The air forcedly flows through the flow furnace (1), where it is heated to the inactivation temperature, preferably the temperature is at least 80°C, especially preferably at least 150°C, while it is less than 200°C. The retention period of the air in the flow furnace (1) is at least 3 to 5 seconds pursuant to the reached inactivation temperature. At the output from the flow furnace (1) the air enters the countercurrent heat exchanger (2) where the heat is transferred to the air inflowing to the flow furnace (1). The device includes the heat exchanger (2) where the inflow of the air to the flow furnace (1) and outflow of the air from the flow furnace (1) are connected to the exchanger (2). The inflow of the air to the flow furnace (1) is connected to the warm end of the input branch of the exchanger (2) and the outflow of the air from the flow furnace (1) is connected to the warm end of the output branch of the exchanger (2). In the flow furnace (1) there can be at least one grid (6) for one meter of the air's course in the flow furnace (1). The grid (5) can be placed across inside the channel; the openings in the grid (5) are designed for air flow.

Description

[0001] AIR FLOW STERILIZATION METHOD AND AIR STERILIZATION DEVICE

[0002] Field of

[0003] The invention concerns air flow sterilization, mainly large volume air flow sterilization, during which no germicidal emitters are used, and which is capable of long-term, continuous operation in space with people and / or animals. The invention also describes sterilization device with the flow furnace and the heat exchanger, in which the air entering the device is pre-heated by the heat gathered during the cooling of the air outflowing from the flow furnace.

[0004] Prior state of the art

[0005] In order to inactivate the pathogens, mainly viruses and bacteria in the air, a UV radiation with the suitable wavelength is commonly used, or high-temperature treatment, ozone treatment, mechanical filtration are used, or disinfectants or chemicals are used, or combination of said methods is used. The UV radiation is dangerous to human health and during the open UV radiation no people or animals can be present in the space. A partial solution is to lock the UV emitter in the separate room thorugh which the air flows from the room. The UV light generating lamps have relatively low hourly lifetime and it is also difficult to ensure that during the high air flow every air particle inside the device is radiated.

[0006] Publication US5441710A discloses sterilization by means of increased temperature where the air flows spirally in the cylindrical chamber with the elements to support the turbulent flow. The device’s volume performance is very limited and it is not usable in light of current demands.

[0007] The article “Thermal Disinfection of SARS-CoV-3 within an Airplane” by Austin Hehir from 2021 discloses the device placed on board of a plane, which includes ventilator and heating spiral. The volume performance of the device is small and the size of the device compared to is volume performance is relatively high, which is an obstacle to more general deployment.

[0008] Current knowledge during the investigation of contaminated aerosol led to WHO recommendations that the clean air exchange in the medical facilities is ensured at level of 160 l / s per patient, which leads to high volume demands put upon existing air conditioning. Sucking the air from the exterior is energetically costly, since apart from filtration one needs to ensure correct air temperature where the heating or cooling of the air to the room temperature level requires a lot of expended or taken energy. In case the pure air is to be obtained by mechanical filtration of the air sucked in the interior, a problem with the rapid clogging of filter inserts occurs, whereby there replacement or cleaning, respectively, is complicated by the fact that their contamination can be dangerous. It can be stated, in general, that the transfer of various airborne diseases is scientifically proven, but no methods or devices are available which could eliminate this way of spreading in required large volume.

[0009] Such method of air sterilization, as well as device for its realization, is therefore desired, which would allow to simply and reliable destroy or inactivate pathogens contained in the air in large volume, whereby there would be no undesired effects on the environment with people and animals present.

[0010] Essence of invention

[0011] The abovementioned deficiencies are significantly remedied by a method of air flow sterilization by means of increased temperature, during which the air flow is heated to at least 80°C and its temperature remains at this level for at least 3 seconds, according to this invention, whose essence lies in the fact that the air forcedly flows through the flow furnace where the air is heated to inactivation temperature, after the outflow from the flow furnace the air enters the countercurrent heat exchanger where it hands over the heat to the air which enters the flow furnace. The inactivation temperature will usually not surpass 200°C, preferably it will not surpass 190°C.

[0012] In the heat exchanger the air is pre-heated before entering the flow furnace, and this also cools the air outflowing from the flow furnace. The air outflowing from the flow furnace and subsequently entering the heat exchanger outflows from the device without active biological structures already. The term “sterilization” in this text generally denotes the process of eradication and / or inactivation and / or degradation of the pathogens in the air, mainly viruses and bacteria in the aerosol carrier.

[0013] The important feature of the proposed invention is the connection of the flow furnace with heat exchanger into a gas-proof system in such a way that the pre-heating of the air entering the flow furnace is ensured, whereby the heat with which the sterilized air outflows from the flow furnace is used for pre-heating. The heat exchanger decreases the energy demands of the device and, at the same time, the air is cooled after heating for inactivation temperature, thanks to which the outflowing air can enter the space with people.

[0014] The air purifiers known in the prior art which are used for air heating operate with relatively low flows in order to achieve at least minimal time of retaining the air in the desired temperature. It is not decisive if the air has relatively high temperature at the outlet, since the overall heat transmitted to the space is relatively small. The goal of this invention is to achieve high air flows so that quick exchange of air in a given space is achieved. In the arrangement pursuant to this invention it is thus necessary to achieve the smallest possible temperature increment at the device’s output as compared to the temperature at the input. Heat exchanger not only helps to achieve this goal, but the energy balance of the device also decreases. Compared to the prior art, for example, compared to publication WO 0128633 A1 , the temperatures beyond 200°C are not used. The lower temperatures during the sterilization of air are also known, but in such case the sterilization is not accompanied by the exchange of the heat in the countercurrent exchanger or in the independent countercurrent exchanger, respectively, where the amount of heat and the temperature fallout is in known methods of heat sterilization lower.

[0015] The term “flow furnace” in this text denotes any device which includes a channel for guiding the air, whereby the channel is equipped by elements for air heating. The air heating can be ensured in various ways, for example, by gas furnaces or, preferably, electrically, which allows for simple possibility of temperature regulation. The flow furnace can also be called a flow heater or heated channel, and so on.

[0016] Inactivation temperature is an air temperature during which the viruses, bacteria or other biological pathogens disintegrate, or they are damaged or otherwise deactivated. The air must remain in the flow furnace during inactivation temperature for some time which is necessary for achievement of the desired deactivation process. It holds that the higher the temperature, the shorter the time necessary to achieve the sterilization effects or to achieve sterilization effects at least at 95% level. The results of the research pursuant to table on figure 1 show that at higher temperatures the short retention period suffices, in order of seconds, which is significantly less than the period in the prior art, which is in order of minutes.

[0017] In the preferable arrangement air can be heated to at least 100°C, especially preferably to 150°C. At 150°C, the retention period can be 3 to 5 seconds. The retention period required at given inactivation temperature defines the speed of flow at the given length of the channel of the furnace flow. The relatively short retention periods allow to achieve high volume flows of sterilization. In order to achieve reliable the prescribed parameters of temperature and retention period, it is preferable if the method includes measuring the air flow and the measuring of the actual temperature at least in one point of the flow furnace and pursuant to the measured data the air flow is regulated and / or the power supply of air heating elements is controlled. At the same time, a curve defining the relationship between the inactivation temperature and the retention temperature for the particular dangerous pathogen which is to be eliminated from the air can be used. During the start of the device when the flow furnace is being heated, the control unit will set low air flow, which would ensure longer retention period. The ventilator speed can be set by frequency converter. The flow can be measured by the sensors, preferably outside the inactivation temperature zones, or the flow can be indirectly assessed on the basis of actual ventilator speed by using the features of ventilator at the given pressure loss. The course of the method is controlled by the control unit which has a respective software, assesses the data from sensors, and, inter alia, controls the speed of the movement of the air in the flow furnace. The control unit can be updated in such a way that the curve defining the relationship between inactivation temperature and the retention period pursuant to the pathogen in the actual pandemic state can be actualized. For example, when the features of the new virus variant are recognized, the actualized curve can be uploaded and the control unit sets the respective retention period and the inactivation temperature.

[0018] The heat exchanger is connected in such a way that the air entering the device is led to the cold end of the input branch of the exchanger. The air proceeds to the warm end of the input branch of the exchanger; the warm end of the input branch is connected to the input of the flow furnace. The output from the flow furnace is connected to the warm end of the output branch of the heat exchanger, from which it follows to the cold end of the output branch of the heat exchanger. The input and output branches of the heat exchanger are oriented in such a way that the air in the input branch flows against the direction of the air flow in the output branch, which ensures the desirable temperature gradient in individual zones of heat exchanger.

[0019] An important feature of the proposed invention is the gradual transfer of the heat from the output air to the matter of the input air in at least three subsequent and subsequently connected countercurrent exchangers or at least in three separate and heat separate members (parts) of the countercurrent exchanger.

[0020] The abovementioned deficiencies in the prior art can be significantly remedied by the device for the air sterilization by means of increased temperature itself, which includes a ventilator and a flow furnace arranged for heating the air at least to 80°C, where the ventilator is connected to the forced air flow in the flow furnace, according to this invention, whose essence lies in the fact that it has heat exchanger, where the input (inflow) of the air to the flow furnace and output (outflow) of the air from the flow furnace are connected to the heat exchanger in such a way that the input into the to the flow furnace is connected to the warm end of the input branch of the heat exchanger and the output of the air from the flow furnace is connected to the warm end of the output branch of the heat exchanger and between the input and output branch a heat-transfer element for the transfer of the heat between the two branches is present in the exchanger. In the preferable arrangement, the flow furnace is arranged for the heating of the air to at least 100°C and less than 200°C, especially preferably to 150°C.

[0021] The flow furnace’s channel’s length is x times the course which the air propelled by the ventilator travels during one second. The value “x” denotes the retention period. If the retention period is 5 seconds, the channel’s length is at least 5 times the course of the moving air per second. For example, if the flow speed is 1 m / s and the retention period is 5 seconds, the channel’s length is at least 5 meters.

[0022] The flow furnace is equipped by the elements for air heating. In the preferable arrangement the flow furnace has at least one electric heating element whose power supply is controlled by the control unit. The electric heating element can be a commercially available heating spiral which is used in electric furnaces or in kitchen ovens. The heating spiral can be placed directly inside the flow furnace’s channel, where it is in direct contact with the flowing air. An arrangement is also possible where the heating element is heated by the waste heat from the technological devices in the industrial operations or by the waste heat from the vehicle engines or by gas burners or by heat pumps, and so on.

[0023] The flow furnace’s channel is adjusted for air flow, whereby the temperature field in the channel should be as homogeneous as possible. After the stabilization of the operation regime, the temperature differences in the 80% of the channel’s volume should be minimal, less than ±5°C. A non-homogeneous temperature is expected for first 20% of the length, at the beginning of the channel; the subsequent 80% of the channel’s volume can reliably ensure inactivation temperature of the air during the retention period.

[0024] The channel must have low air flow resistance and minimal heat losses through the channel’s sheath. The flow cross-section in each point of the flow furnace’s channel reaches at least the value of referential cross-section. The referential cross-section corresponds to minimal flow cross-section of the whole device, which can be preferably defined by a crosssection of the entry opening of the device. Subsequently, all channels’ cross-sections in the device, that is, cross-sections in the flow furnace, in the heat exchanger and in the connecting pipes have a flow surface same or larger than referential cross-section S. The device can also be construed in such a way that subsequently in the direction of air flow the number of channels increases, which minimizes the air flow resistance and the pressure losses.

[0025] In order to achieve high efficacy it is necessary that each particle of air is reliably preheated to the inactivation temperature and it remains at inactivation temperature during the retention period. In order to achieve this goal the flow furnace can have at least one grid inside the channel with the flowing air. The grid is placed transversally in the channel so that the air is forced to flow through the openings in the grid. This increases the statistical probability that each particle of air meets the solid hot surface which transmits its heat to it. The grid can be placed perpendicularly onto the flow of the air, or with the slope of 60°. The grid covers at least 90% of the channel’s cross-section and usually it will cover whole flow cross-section of the channel. The openings in the grid are relatively large so that the grid does not substantially increase the flow resistance and it is not clogged with dust during pause, which would raise the need for its cleaning. Usually the openings in the grid will have total surface of at least 4 mm2. The summary cross-section of the openings in the grid will correspond at least to the referential cross-section S. The grid has an inactivation temperature and the material of the grid homogenizes the temperature field by its heat conductivity.

[0026] The grid can be formed by metal mesh, drawn metal, perforated sheet metal, and so on. It has been proven preferable during inventing if there is at least one grid per one meter of the channel’s course, preferably at least five grids. This increases the statistical probability that with any type of air flow each air particle will enter into contact with the heated surface of the grid. It is preferably from the technological point of view of the system of the grids is formed as a single piece from the strip of perforated material which is pleatedly folded into folds where each fold of the strip is a single grid. In this arrangement the pleated strip is simply attached inside the channel.

[0027] An arrangement is possible, too, where the air heating element has a form of a grid. In such case a resistance grid, for example, which generates the heat on all its surface, is used instead of common heating spiral. The edges of the heating grid are attached in the insulation frame and the overall surface of the openings in the heating grid is at least at the level of referential cross-section S.

[0028] The fan acts as a propelling unit and it can be included at the entry to the device or at the device’s output where it is not exposed to increased temperature, since at the output of the device the temperature of the outgoing air is increased compared to the input only by few Celsius degrees. In general, the fan can be placed in any point of the device. If the fan is placed at the input of the device, it works with the contaminated air which it pushes into the device. If the fan is at the output of the device, it sucks the already sterilized air. In order to achieve desired high flow capacity, it is preferable if the fan or the series of fans have the flow of at least 101 / s, 36 m3 / h, preferably at least 1001 / s, 360 m3 / h. The energy consumption for the forced air flow in the device according to this invention is less than 2 Wh / m3of the transferred air, which is much less than during the mechanical filtration through filtration inserts capable of capturing the biological pathogens. The noise of the fan or group of fans is less than 45 dB, so the device can be placed directly in the room where it purifies the air with people present.

[0029] The flow furnace, the heat exchanger and their connections must be hermetically tight so that all air entering the device travels without leaks onto the device’s output. Since the device does not need filtration elements for its operation, it has low pressure loss and the forced air flow is ensured by the fan with low energy consumption and low noise. The device can include multiple fans employed in parallel or in series.

[0030] The flow furnace and, preferably, the heat exchanger and their connections, too, are heat insulated from the environment in order to ensure low heat loss of the device. This intensifies the heat transition in the heat exchanger between the inflowing and outflowing air from the flow furnace. A commonly available construction heat isolation, preferably nonflammable mineral wool-based isolation, can be used. When using 50 mm of the thick isolation there are low overall heat losses. The heat losses can decrease in such a way that the air entering the device flows around the output branch of the heat exchanger. The heat losses on the surface of the device are usually less than 500 W / h pursuant to the quality of the used isolation. The minimization of the heat losses is desired in the summertime, mainly. In the transitory and winter time, the heat loss through the device’s surface can help to heat the space, too.

[0031] The use of at least three heat exchangers connected subsequently, or splitting of the heat exchanger to at least three thermally separate members, respectively, may appear as redundant at low temperature gradients, but it brings advantage in that there is no spreading and transmission of heat through the construction of the heat device itself alongside the direction of air flow or against the direction of air flow, respectively, even during the long-term operation. The number of subsequently ordered heat exchangers or the number of subsequently connected thermally separated members of the heat exchanger was preferably chosen in such a way that the temperature gradient in a single heat exchanger or in a single member is not more than 30°C, preferably not more than 20°C. For example, in inactivation temperature 150°C, and room air temperature being 20°C, there are 7 thermally separate members with mean difference ca. 18,5°C for the difference (150 - 20)°C. The thermal separation of the members means that the heat transfer takes place only by air flow, not by construction of the bodies of the members or by heat exchangers themselves. The main transfer, at the same time, happens through the heat transmitting element in the member or exchanger itself, respectively.

[0032] The heat exchanger in the preferable arrangement is composed from at least three members which are independent or mutually thermally separate, whereby the members are connected subsequently. Outwardly, the members can form a single whole. For the purposes of terminological clarity, the term “heat exchanger” in this text means at least one heat exchanger, but also a whole comprising multiple exchanger members and also the single system of multiple heat exchangers ordered subsequently.

[0033] The heat transmitting element which physically separates the air of the input and output branch and which, at the same time, ensure the transfer of the heat between these branches, is thermally separate (heat insulated) from the heat transmitting element of the neighboring member. The splitting of the heat exchanger into independent members or into members whose heat transmitting elements are mutually insulated ensures that even during the long-term operation there is no nivelization, no leveling out, of the temperatures in the heat exchanger zones due to the transfer of the heat alongside heat transmission element. It is preferable if the heat transmits through the heat transmission element in the maximum possible way, that is, basically perpendicularly onto the air flow direction. The heat transmission element is produced from material with high heat conductivity, preferably the conductivity is 100W / mK, especially preferable more than 150W / mK. In the preferable arrangement the heat transmission element is produced from aluminum (heat conductivity 180 to 226 W / mK), for example in form of extruded aluminum profile with ribs. In another arrangement the heat transmission element can be produced from shaped aluminum, for example from sheet metal extrusions with ribs or from foam aluminum, too, which has low heat capacity at high heat conductivity and also low external specific density, which decreases the overall weight of the device.

[0034] In order to achieve compact construction of the heat exchanger and thereby low outside surface, too, which would be necessary to heat isolate, it is preferably if individual elements of the heat exchanger are composed into a single whole where output of one member directly follows upon the input of the following member, whereby all heat transmission elements are separated by the board with low heat conductivity, that is, conductivity below 1W / mK. The board is gas-proof and it forms a partition between the members and it is preferable if the board’s material has low thermal expansivity (less than 2.10'6K'1). Preferably the board is from glass. Glass can be cleaned easily and it has low heat conductivity. It is preferable if the glass is treated by heat and resistant against formation of ruptures.

[0035] The exchanger is composed of at least three, preferably at least six mutually thermally isolated heat transmission elements organized serially in such a way that their temperature rises from the primary entry of the air, and the temperature is not nivelized, not leveled out, even during continuous operation. Thanks to this arrangement with mutual isolation one can achieve very low temperature difference at input and output; in last member the temperature difference can be less than 2°C compared to the outer air’s temperature in the room. At inactivation temperature 150°C, 12 members proved to be more than sufficient.

[0036] Heat exchanger can include bypass valve which releases the air from the flow furnace to the output of the device before the complete cooling in the last section of the heat exchanger. Such arrangement can fulfill the heating function in the winter or transitory time. In such case the air at the output from the flow furnace is cooled only to the heating temperature, for example 60°C or 40°C, and it is released to the heated space. In this method the output temperature can be set pursuant to heat performance of the flow furnace so that the available heat performance of the flow furnace is used primarily to cool the air after its sterilization. Such arrangement allows to use available electric performance to heat during the winter and transitory period, which can be combined with the renewable sources of electric energy, for example with photovoltaic panels or local wind power. In case of local surplus of the electric energy, this can be used for heating in such a way that the sterilized air is released from the device before its total cooling in the countercurrent exchanger.

[0037] In principle it will hold that the lowest possible difference of temperatures between the input and the output of the device is sought, which is achieved by as effective a heat exchange between the heated air running out of the flow furnace and the air flowing into the device. Thanks to this heat exchange the air flowing into the flow furnace is pre-heated and the flow furnace increases the temperature of the air from the temperature of the pre-heated air to the inactivation temperature. The demand for as low a difference between the temperatures at the input and output pursues a goal of not increasing the temperature of the room with the purified air during summertime. As the operation of the device according to the example in this text has shown, the overall heat increment of the device (proven by consumption of electric energy after the heat ratios are stabilized) is up to 1 kWh / h, which roughly corresponds to heat input of 6 people during a very light manual work. Such heat increment is negligible in spaces where this device is expected to be used, such as gyms, concert halls, public spaces, stations, airports, and so on.

[0038] The air outflowing from the output branch of the heat exchanger always has a temperature which is slightly higher than that of the air inflowing into the input branch of the heat exchanger, since the transfer of the heat takes place at different temperature potentials and it is not possible to achieve at the short time at least limit nivelization, limit leveling out, of the temperatures. The heat outflowing from the device will usually be 4°C to 10°C hotter, pursuant to the set inactivation temperature and the number of independent members of the exchanger. Such fact protects the cooling zones of the heat exchanger from condensation of water vapor, since nowhere in the whole process has the air in the device lower temperature than the air temperature at the input. This is important for ruling out the risk of waterlogging (inundation) of the device. It is not ruled out, at the same time, that by the end of the otput branch of the heat exchanger or by the end of the air outflow from the output branch of the heat exchanger the air would be, furthermore, cooled, for example by water cooler, by a Peltier cell or by removing heat into the latent heat of a suitable material. Such suitable material can be wax, whose melting temperature is set at the level of interior temperature. Wax can be penetrated into the block of aluminum foam and it can serve as heat accumulator from which the heat can be subsequently taken, for example, by means of use water flow.

[0039] In the preferable arrangement the heat exchanger includes at least six countercurrent members. In such case the temperature gradient for a single member can be expressed as (T in furnace - T in environment) / 6. Even during the long-term operation the members maintain different temperature of the heat transmission element where this temperature gradually rises from the cold end of input branch and cold end of the output branch towards the got end of the input and output branch. The individual members are arranged in such a way that the sucked cooler air flows on the opposite side of the member as the blown out hotter air, whereby there is heat transmission between them from the higher temperature to the lower. The heat transmission element’s surface is increased by ribs on both sides. On both sides, the air flows around the ribs. The surface of the heat transmission element should be at least double, preferably at least five times larger compared to the other surfaces of the member’s vent. It is preferable if all walls of the member’s vent, that is, walls outside the heat transmission element, are formed from the material with low heat conductivity, that is, heat conductivity less than 1 W / mK. At the same time, the material used for the vents’ walls should have low heat expansivity, less than 2.1 O'6K’1, so that the stress due to different temperature of the vent on the input and the output of the heat exchanger is minimized. Preferably, the wall of the vent is formed by glass board, where the glass board at the same time forms an isolation between the heat transmission elements of the neighboring members. Each vent of the member has free flow cross-section at the level of at least referential cross-section S.

[0040] It is an advantage of the invention that the high flow capacity of the device has minimal energy demands, whereby the thermal processing of the air is harmless to people and animals, too, it does not produce harmful substances, it does not produce waste during operation, and it does not even demand one-off consumables. The device can achieve air flows at the level of 1001 / s, 360 m3 / h, whereby it suffices to connect it to a single-phase electric socket. The energy demands and noise are low. The device pursuant to proposed invention does not require control by personnel; after it is turned on an thermally stabilized, it can operate autonomously and continually. The device is not dangerous to the environment, does not radiate harmful radiation, does not produce ozone, and does not keep filtration materials which could capture pathogens dangerous during maintenance. The operation of the device greatly decreases the maintenance demands, there are not filters in the device or components with limited durability, as it is the case in cases of purifiers using UV radiation or ozone.

[0041] An important advantage of the proposed invention is the compact construction of the device with regard to volume performance, which is capable to control the device even during continuous operation. The device with the approximate external volume of 2 m3is capable of sterilizing 200 m3 / h at inactivation temperature 150°C and retention period 5 seconds. This ration between the relatively low volume of the device and high volume performance is crucial for the broad applicability of the device. Compared to the devices known in the prior art, this ratio (100 m3 / h for 1 m3of the device’s volume) is orderly more favorable than the known devices - 10 to 50 times more favorable. Thanks to this the device pursuant to the proposed invention can be easily mounted in various spaces or in vehicles, airplanes, ships, trains, buses, or means of mass transport.

[0042] The sterilization method pursuant to the proposed invention is harmless to humans and domesticated animals and therefore it can be mounted in full operation mainly in space where there are many people and where there are large amounts of air which must be purified in short intervals. The sterilized air maintains its original humidity and composition and roughly the same temperature, too. The method and device are suitable for decontamination of the spaces with regard to human coronaviruses such as SARS-CoV-2, but the method and device have much larger uses, since it is possible to eradicate by high temperature basically all dangerous airborne microorganisms, such as further influenza viruses, reoccurring measles viruses, mumps, chicken pox, or groups of rhinoviruses causing various colds and flus. Meanwhile, the sterilization of the air is capable of destroying the airborne bacteria such as bacillus tuberculosis, mycoplasma pneumoniae, some strains of streptococci, or coxiella burnetii, which causes highly contagious Q fever.

[0043] Description of drawings

[0044] The invention is further disclosed by drawings 1 to 5. The depicted ratio of individual elements, the shapes and cross-sections of channels and vents, as well as depicted body of the device and the number of displayed members, are only examples and cannot be interpreted as limiting the scope of protection.

[0045] Figure 1 is a graph with results of the research which found the relationship between the inactivation temperature and the retention period sufficient for inactivation of SARS-CoV-2 virus.

[0046] Figure 2 is a schematic cross-section of the flow furnace with the heat exchanger. The arrows depict the direction of the air flow. The dotted line on the outer side of the flow furnace denotes heat isolation. The heat transmission element is depicted by full line into which the white dotted line is inserted, which schematically depicts the permeability for the heat conductance.

[0047] Figure 3 is a schematic cross-section of the heat exchanger with six members which are ordered into a single body, but which are mutually separated by isolation boards. The isolation boards are depicted by full line; the heat transmission element is depicted by full line into which the white dotted line is inserted, which schematically depicts the permeability for the heat conductance.

[0048] Figure 4 subsequently schematically depicts the connection of six members as connection of six independent heat exchangers one after another, and it does so in two versions: in straight connection or cross connection.

[0049] Figure 5 is cross-section of vent with heat transmission element with ribs.

[0050] Examples of realization

[0051] Example 1

[0052] In this example the device has outer body with the shape of the box which can be placed directly into the space in which there are people and / or animals or it can be placed in the room with air conditioning devices, where it is connected to the air distribution, whereby the air is sucked and subsequently blown out into the space with eventual permanent presence of the people and / or animals.

[0053] On the outer sheath of the box there is an input for the air, output for the air, control elements and control unit’s display. The device in this example is arranged in a box, similar to that used for electrical distribution purposes.

[0054] The body of the flow furnace 1. is formed by the box made of stainless steel sheet with vertical partitions. The partitions delimit, in this example, four chambers of the channel, where the partitions alternately adhere to upper or lower wall of the box, while on the opposite side they form a gap for transition of the air to the neighboring chamber of the channel. With this arrangement, the sufficient length of the air’s course can be produced in the box; in this example the course is ca. 5 m.

[0055] In each chamber there are elements 4 for heating of the air, in this example these are electric heating bodies, whose outer surface is designed for direct contact with the air. Air heating elements 4 are woven into the inside of the channel and from the outer side the electric power supply lines are connected to them. Air heating elements 4 are controlled by the control unit. In each chamber there is a system of grids 6 composed from the strip of drawn mesh metal. The strip is pleated into folds adhering to the channel’s walls. The strip is hung to the upper and lower heating element 4. At multiple places the flow furnace is equipped by temperature sensors connected to the control unit.

[0056] The heat exchanger 2 in this example comprises of twelve countercurrent members 7. For the purposes of clarity, only six members 7 are depicted in the drawings. Individual members 7 are arranged in such a way that the sucked cooler air flows on the member’s 7 side opposite to the blown out hotter air. The heat transmission element 5 from the extruded aluminum has ribs, whereby in both branches the air flows around the ribs. The other walls of the member’s 7 vent are delimited by glass board 8 with heat conductivity less than 1 W / mK. The glass board 8 separates the heat transmission elements 5 of the neighboring members 7.

[0057] The first fan 3 is placed on the device’s input, the second fan 3 is on the device’s output. Both fans 3 are controlled by frequency converter pursuant to instructions from control unit.

[0058] The air flows forcedly through the flow furnace 1_ where the air is heated to the inactivation temperature 150°C, and it remains at this temperature for ca. 5 seconds, and subsequently it flows out form the flow furnace 1_ and enters the countercurrent heat exchanger 2 where the heat is transferred to the air entering the flow furnace 1_.

[0059] The flow furnace 1_, the heat exchanger 2 and their connections are heat isolated from the outer environment by means of non-flammable isolation with thickness at least 50 mm.

[0060] The device pursuant to this example is supplied by power from a single-phase socket; it reaches the performance of 100 m3 / h, whereby after the temperature stabilization the power consumption is 1 kW. The air flowing out of the device has a temperature that is ca. 6°C to 8°C less than temperature of the inflowing air.

[0061] Example 2

[0062] Device is mounted in the mean of mass transport, where, at first, the waste heat from the combustion engine is used to heat the air close to 100°C, and subsequently the air is heated to 150°C by electric spiral. In order to decrease the weight, the heat transmission element 5 is made from aluminum foam.

[0063] Example 3

[0064] In this example the device is combined with heat pump in which there is a regime for the air sterilization and also for sterilization combined with heating of the space. At the same time, the heat pump is used for cooling the air at the output, down to the temperature of inflowing air.

[0065] Industrial applicability

[0066] Industrial applicability is obvious. According to this invention it is possible to industrially and repeatedly sterilize large amounts of air and thereby prevent aerosol contagion, for example in hospitals, schools, cinemas, theaters, gyms, congress halls, restaurants, but also in closed production sites with large movement of personnel, or in means of transport, airplanes, trains, buses, and so on.

[0067] List of symbols

[0068] 1 - flow furnace

[0069] 2 - heat exchanger

[0070] 3 - fan

[0071] 4 - heating element

[0072] 5 - heat transmission element

[0073] 6 - grid

[0074] 7 - member

[0075] 8 - board

Claims

PATE N T CLA I M S1. A method of a flow sterilization of an air by an increased temperature, where the air flow is heated to at least 80°C, where the air forcedly flows through a flow furnace (1) where the air is heated to an inactivation temperature, i s c h a r a c t e r i z e d b y t h e f a c t , that at an output from the flow furnace (1) the air enters a countercurrent heat exchanger (2) where a heat is transferred to the air which enters into the flow furnace (1), whereby the air flows through at least three independent, subsequently connected countercurrent exchangers (2) or the air flows through at least three thermally mutually separated members (7) of the countercurrent exchanger (2).

2. The method of the flow sterilization of the air pursuant to the claim 1 i s c h a r a c t e r i z e d b y t h e f a c t , that the air entering the device is led to a cold end of an input branch of the exchanger (2), the air flows from there to a warm end of the input branch of the exchanger (2), further the air flows into the flow furnace (1), in which it flows and remains at the inactivation temperature during a retention period, and subsequently the air outflows from the flow furnace (1) to the warm end of an output branch of the exchanger (2) and then follows to the cold end of the output branch of the exchanger (2), whereby the air in the input branch flows against the direction of the air flow in the output branch of the exchanger (2).

3. The method of the flow sterilization of the air pursuant to the claim 1 or 2 i s c h a r a c t e r i z e d b y t h e f a c t , that the air is in the flow furnace (1) heated at least to 100°C, preferably at least to 150°C, whereby especially preferably the temperature is less than 200°C.

4. The method of the flow sterilization of the air pursuant to any of the claims 1 to 3 i s c h a r a c t e r i z e d b y t h e f a c t , that the air remains in the flow furnace (1) at the inactivation temperature during the retention period, whereby the retention period in the flow furnace (1) is 3 to 5 seconds.

5. The method of the flow sterilization of the air pursuant to any of the claims 1 to 4 i s c h a r a c t e r i z e d b y t h e f a c t , that it includes a measurement of the air flow and the measurement of the temperature in at least one point of the flow furnace (1), and pursuant to measured data the air flow is regulated and / or a power supply of air heating elements (4) is controlled.

6. The method of the flow sterilization of the air pursuant to the claim 5 i s c h a r a c t e r i z e d b y t h e f a c t , that the air flow is regulated by changing a speed of a fan (3), preferably by means of a frequency converter.

7. The method of the flow sterilization of the air pursuant to the claim 5 or 6 i s c h a r a c t e r i z e d b y t h e f a c t , that the regulation of the inactivation temperature and the respective retention period is set pursuant to a curve defining a relationship between the inactivation temperature and the retention period pursuant to a respective pathogen.

8. The method of the flow sterilization of the air pursuant to any of the claims 1 to 7 i s c h a r a c t e r i z e d b y t h e f a c t , that the air entering the device firstly flows around an isolation sheath of the exchanger (2) or around the isolation sheath of the whole device.

9. The method of the flow sterilization of the air pursuant to any of the claims 1 to 8 i s c h a r a c t e r i z e d b y t h e f a c t , that the air flows in the device with a volume at least 10 l / s, preferably at least 100 l / s.

10. A device for a sterilization of an air by an increased temperature, which includes a fan (3) and a flow furnace (1) designed for a heating of the air to at least 80°C and less than 200°C, where the fan (3) is connected to a forced air flow in the flow furnace (1), i s c h a r a c t e r i z e d b y t h e f a c t , that it includes a heat exchanger (2), where an inflow of the air into the flow furnace (1) and an outflow of the air from the flow furnace (1) are connected to the exchanger (2) in such a way that the inflow of the air into the flow furnace (1) is connected to a warm end of an input branch of the exchanger (2) and the outflow of the air from the flow furnace (1) is connected to the warm end of an output branch of the exchanger (2), whereby between the input and the output branch there is a heat transmission element (5) for a transfer of a heat between the branches, and whereby the device includes at least three such subsequently connected exchangers (2) or the exchanger (2) includes at least three thermally mutually separate members (7).

11. The device for the sterilization of the air pursuant to the claim 10 i s c h a r a c t e r i z e d b y t h e f a c t , that the flow furnace (1) is equipped by air heating elements (4), preferably the elements (4) are electric heating elements which are inside the flow furnace’s (1) channel designed for a direct contact with the heated air.

12. The device for the sterilization of the air pursuant to the claim 10 or 11 i s c h a r a c t e r i z e d b y t h e f a c t , that flow cross-sections in the flow furnace (1), in the exchanger (2) and in connecting pipes have a flow surface same as or larger than referential cross-section S which corresponds to the minimal flow cross-section of the whole device and which can be preferably defined by the cross-section of an entry opening of the device.

13. The device for the sterilization of the air pursuant to any of the claims 10 to 12 i s c h a r a c t e r i z e d b y t h e f a c t , that there is at least one grid (6)placed across inside the channel of the flow furnace (1); openings in the grid (6) are designed for the air flow and individually their surface is at least 4 mm2and summary cross-section of the openings in the grid (6) corresponds at least to the referential crosssection S which corresponds to the minimal flow cross-section of the whole device and which can be preferably defined by the cross-section of the entry opening of the device.

14. The device for the sterilization of the air pursuant to the claim 13 i s c h a r a c t e r i z e d b y t h e f a c t , that the grid (6) is produced from a metal mesh or from a drawn metal or from a perforated metal sheet.

15. The device for the sterilization of the air pursuant to the claim 13 or 14 i s c h a r a c t e r i z e d b y t h e f a c t , that for each meter of the channel’s course there is mounted at least one grid (6), preferably there are 5 grids (6).

16. The device for the sterilization of the air pursuant to any of the claims 13 to 15 i s c h a r a c t e r i z e d b y t h e f a c t , that a system of the grids (6) is produced as a single piece from a strip of a perforated material which is pleatedly folded into folds, where each fold of the strip presents one grid (6) of the system.

17. The device for the sterilization of the air pursuant to any of the claims 13 to 16 i s c h a r a c t e r i z e d b y t h e f a c t , that the grid (6) is at the same time the air heating element (4).

18. The device for the sterilization of the air pursuant to any of the claims 10 to 17 i s c h a r a c t e r i z e d b y t h e f a c t , that the fan (3) is placed at the input and / or the output of the device.

19. The device for the sterilization of the air pursuant to any of the claims 10 to 18 i s c h a r a c t e r i z e d b y t h e f a c t , that the flow furnace (1) and preferably the exchanger (2), too, and its connections are heat isolated from a surrounding environment.

20. The device for the sterilization of the air pursuant to any of the claims 10 to 19 i s c h a r a c t e r i z e d b y t h e f a c t , that the exchanger (2) is construed from at least three members (7) which are independent, whereby the members (7) are connected subsequently, one after another.

21. The device for the sterilization of the air pursuant to any of the claims 10 to 20 i s c h a r a c t e r i z e d b y t h e f a c t , that the members (7) have mutually separate heat transmission elements (5), preferably the heat transmission elements (5) of the neighboring members (7) are separated by a board (8) with a heat conductivity less than 1 W / mK; preferably the board (8) is glass board (8).

22. The device for the sterilization of the air pursuant to the claim 20 or 21 i s c h a r a c t e r i z e d b y t h e f a c t , that the exchanger (2) is construed from at least six members (7), whereby a vent of each member (7) in a transversal cross-section is delimited by a surface of the heat transmission element (5) and the remaining delimitation of the vent is formed by the board (8) with the heat conductivity less than 1 W / mK, preferably by the glass board (8). The device for the sterilization of the air pursuant to any of the claims 10 to 22 i s c h a r a c t e r i z e d b y t h e f a c t , that it includes a control unit to which a flow sensor and / or at least one temperature sensor is connected; preferably it includes a control panel and a display element, too.

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