Method and device for enlarging aerosol particles

Abstract

The invention relates to a method and a device for enlarging aerosol particles, to use of an operating medium for producing an oversaturated vapour, and to a cartridge. In a method of enlarging particles (1) of an aerosol (2), the particles (1) come into contact with an oversaturated vapour (3). In order to produce the oversaturated vapour (3), a carrier gas is heated and then brought into contact with an operating medium (35). In this way, the particles can be activated very quickly.

Description

[0001] Method and device for enlarging aerosol particles

[0002] Description

[0003] The invention relates to a method and a device for enlarging aerosol particles and a storage unit.

[0004] Aerosol particles in the (low) nanometer range cannot be easily detected optically. For optical detection, such particles must first be magnified. In this process, the particles grow by approximately two orders of magnitude, for example, so that optical detection is subsequently possible. This can occur in the 300 nm range, for example. Magnification can occur through condensation growth. This process is also known as activation. In this process, the particles act as condensation nuclei in an atmosphere of supersaturated vapor from a working medium. Typically, the vapor molecules diffuse onto the particles. The particles, enlarged or grown in this way, can then be detected using optical methods.

[0005] An aerosol is a mixture of solid and / or liquid particles in a gas or gas mixture. This gas can serve as a carrier gas. The term "gas" as used in this application refers to the gaseous state and includes pure gaseous substances and gas mixtures. The particles of an aerosol are also referred to as aerosol particles. Aerosol particles can be solid and / or liquid.

[0006] Technically, the particles are enlarged, for example, in a condensation particle counter (CPC), which can detect the total number of particles. The operating fluid is heated in liquid form. This takes place in a saturator through which a carrier gas flows. Depending on the temperature, a partial pressure of the operating fluid, e.g., the saturation vapor pressure, is established in the carrier gas stream. The saturated carrier gas stream is fed into a condenser, which is cooler than the saturator. Due to the lower temperature, the partial pressure of the operating fluid is now supersaturated. Alternatively, supersaturated vapor can be produced by mixing saturated vapor and cooler, especially vapor-free, air.

[0007] As soon as particles come into contact with the supersaturated vapor, they act as condensation nuclei and grow, accumulating the operating fluid. The particles can then be detected using an optical method. For example, the gas stream can be irradiated with a focused light source, such as a laser. For example, radiation scattered by the particles can be detected. This allows individual particles and / or the number or concentration of particles to be detected. The number of particles in a specific time interval can be determined electronically. A condensation particle counter can be configured to count particles down to a size of 5 nm or smaller.

[0008] Optical particle spectrometers are used to determine particle sizes and size distributions. These allow the size and number and / or size distribution (number concentration per size class) of the particles present to be determined starting from a specific particle size, for example, 125 nm, 150 nm, or 250 nm, typically down to a particle size of 4 pm. This allows an optical equivalent diameter to be determined, which is proportional to the intensity of the scattered light. The detector can typically measure the light scattered by the particle at a fixed angle and distance.

[0009] To produce the supersaturated vapor, a liquid is heated until it transforms into the gas phase. Alcohols such as butanol, ethanol, or isopropanol are typically used as the operating fluid. These are often oxidizing or highly flammable, have a strong odor, and / or are harmful or even toxic. Comprehensive safety precautions are therefore required during handling and use. In special cases, diethylene glycol (DEG) is also used as the operating fluid, although this requires additional activation in a downstream CPC. In special applications, it is also possible to use fluorinated hydrocarbons such as perfluorotributylamine (PFTBA). However, this is harmful to health and severely polluting the climate.

[0010] What the known methods have in common is that the respective operating medium is heated to produce supersaturated steam. This is technically complex and time-consuming, as heating the operating medium and generating the supersaturated steam requires a long preheating period before a measurement can be taken. Furthermore, particularly in portable devices and special applications such as clean rooms, aerospace, or passenger transport, handling is subject to restrictions or is only possible to a limited extent. The above-mentioned features, effects, and definitions can be combined individually or in multiples with the claimed and described subject matter.

[0011] The object of the invention is to improve the magnification of aerosol particles, particularly for the optical determination of aerosol properties. Preferably, the aforementioned disadvantages of the prior art are to be at least partially remedied.

[0012] This object is achieved by the method according to claim 1, as well as by the device and storage unit according to the independent claims. Advantageous embodiments are specified in the subclaims.

[0013] To solve this problem, a method for enlarging aerosol particles is used, in which the particles come into contact with a supersaturated vapor. In one embodiment, a carrier gas is heated to produce the supersaturated vapor. The heated carrier gas can then come into contact with an operating medium.

[0014] It has been found that heating the carrier gas is possible much faster than heating the operating fluid, as practiced in conventional processes. Furthermore, saturated vapor can be generated much more quickly. A state in which particle activation can occur can be quickly established, typically within seconds. A lengthy heating phase is eliminated. Furthermore, heating the carrier gas is technically simpler than heating the operating fluid.

[0015] The operating fluid typically enters the gas phase upon contact with the heated carrier gas. This means that the operating fluid, or a substance formed from the operating fluid, is in gaseous form. A supersaturated vapor can then be created, and the aerosol particles to be detected can serve as condensation nuclei upon contact with the supersaturated vapor, enabling them to be activated by the supersaturated vapor.

[0016] The supersaturated vapor can be produced by cooling non-supersaturated vapor and / or by mixing saturated vapor with cooler, particularly vapor-free, gas. Non-supersaturated vapor can be saturated or non-saturated vapor. The vapor-free gas can contain particles.

[0017] Supersaturated vapor contains more gas particles than would be the case in thermodynamic equilibrium. Supersaturated vapor therefore has a higher partial pressure than vapor in thermodynamic equilibrium between vapor and condensate. The vapor pressure is above the saturation vapor pressure. If condensation nuclei are added, condensation can occur in the supersaturated vapor, which can eventually lead to thermodynamic equilibrium.

[0018] The particles or aerosol can already be present in the non-supersaturated vapor and, if necessary, be cooled with it. Cooling can then convert the non-supersaturated vapor containing particles into supersaturated vapor containing particles. It is therefore not necessary for the particles to be introduced into the already supersaturated vapor.

[0019] The carrier gas is a gas or gas mixture that absorbs or carries the operating medium. In particular, a stream of the carrier gas is heated and / or brought into contact with the operating medium. A stream of the gas to be analyzed containing the particles can serve as the carrier gas. Alternatively or additionally, a particle-free gas can be used as the carrier gas. Such a gas can be produced from ambient air and / or purified using a particle filter. Particle-free gas and / or, in particular, saturated vapor can be mixed with the gas to be analyzed. A gas stream can be pumped and / or controlled by a mass flow controller (MFC).

[0020] The carrier gas is heated and can then come into contact with an operating medium. This means that the heated carrier gas comes into contact with the operating medium. The heating and contact do not necessarily have to take place one after the other, but can take place simultaneously, for example in a continuous process. The heating and contact do not necessarily have to take place in different locations, but can take place at the same location or in the same unit. For example, a contact space can contain a heating area and a contact area that are arranged directly next to each other. In the heating area there is a heated object that transfers heat to the carrier gas, e.g. a wall, and the operating medium can be arranged upstream of this, possibly directly adjacent.

[0021] In one embodiment, the method is carried out in a particle counter, preferably in a CPC, in particular in an ultrafine aerosol condensation nucleus / particle counter. In one configuration, the particles have a diameter of less than 50 nm, in one embodiment less than 23 nm, in particular less than 10 nm, and preferably less than 5 nm or less than 3 nm. The particles have the stated diameter before they come into contact with the supersaturated vapor. In particular, this refers to the average diameter of a large number of particles. Growth or enlargement then takes place based on this diameter.

[0022] It has been shown that even very small particles can be magnified using the method according to the invention. In particular, these particles can be optically detected after magnification.

[0023] The operating medium can be one of the known operating media mentioned above or another liquid operating media. Alternatively or additionally, a solid can be used, as described below.

[0024] In one embodiment, a solid is used as the operating medium. The solid is suitable for transitioning into a gas phase, for example by sublimation or deposition due to chemical affinity. A supersaturated vapor can be produced, and the particles can be activated by the supersaturated vapor. The solid operating medium can be heated directly or indirectly. Direct heating can be achieved, for example, by light, for example infrared radiation, or by microwave radiation. Indirect heating can be achieved by heating an object that can transfer heat to the solid by conduction, for example a wall. The solid operating medium can be heated by means of a heated carrier gas in order to transition into the gas phase. A solid operating medium can be arranged in or on a storage unit. A storage unit can be heated directly.A solid operating medium is solid at room temperature or at the temperature prevailing in the environment of the device during the process. The operating medium typically remains solid until the components that transition into the gas phase. Typically, the operating medium present in the device does not become liquid. The entire operating medium or most of it therefore remains solid. However, it cannot be ruled out that, for example, a liquid or quasi-liquid layer may form on the surface.

[0025] In addition to sublimation, it is also possible for a solid operating medium to be decomposed by the heated carrier gas and / or by direct or indirect heating, or to undergo some other chemical reaction. Instead of condensation, activation can then occur through the deposition of solid and / or liquid substances that, for example, are the operating medium itself (recombination of the decomposed substance) or have originated from it. For example, ammonium chloride decomposes upon exposure to heat and recombines upon cooling, so that the particles are again activated with ammonium chloride. This behavior is also referred to as pseudo-sublimation.

[0026] In principle, a solid can be used that is capable of forming a gas upon increasing temperature, preferably without forming a liquid phase in the meantime. If the resulting gas is in a supersaturated state, it is typically capable of enlarging particles through deposition, preferably by direct deposition in the solid state from the gaseous state.

[0027] The use of a solid material significantly simplifies the measuring device and the process. There is no need to use and refill liquid operating fluid, which has previously been a significant expense, especially in clean rooms. No lines for the liquid operating fluid, no humidifier, and no associated heating devices are required. No oxidizing, highly flammable, strong-smelling, or harmful substances are required. Furthermore, solid operating fluids have significantly lower consumption than liquid operating fluids. Refilling is therefore required less frequently. Furthermore, a large storage container is no longer required.

[0028] Avoiding alcohols offers further advantages. Firstly, they are flammable, have a strong odor, and are sometimes toxic. Furthermore, alcohols' heating capacity is limited due to their flash point and / or boiling point, which also limits the maximum temperature of the saturator, thus the maximum supersaturation and the lower limit of particle detection. Using a fixed operating medium, smaller particles can be activated for detection.

[0029] In sublimation, the transition to the gas phase depends heavily on the temperature of the gas stream, which can be changed rapidly. In contrast, in evaporation, the transition to the gas phase depends more strongly on the temperature of the liquid to be evaporated, which can only be changed more slowly. Heating the gas stream and bringing the solid operating medium into contact with the heated gas stream is therefore particularly advantageous.

[0030] In one embodiment, the operating agent is selected from: a sulfone, e.g., dimethyl sulfone, a sulfoxide, camphor, iodine, naphthalene, a benzene compound, e.g., benzene acid, salicylic acid, ferrocene, anthracene, sulfur, dichlorobenzene, menthol, pyrene, benzenephenone, caffeine, arsenic, phthalic anhydride, a fullerene, and ammonium chloride.

[0031] In principle, any solid capable of sublimating or decomposing and recombinating as described above can be used. However, if high temperatures are required for this, this is associated with some disadvantages. Accordingly, the operating medium is preferably a substance with a low sublimation pressure, for example, a substance that at least partially sublimes under negative pressure or atmospheric pressure in the range of room temperature or, for example, at a temperature above 20°C and / or below 100°C, typically 80°C, in particular 60°C, and preferably 40°C. Rapid heating of the carrier gas allows for rapid sublimation and thus the generation of saturated or supersaturated vapor.

[0032] Ferrocene, caffeine, or salicylic acid can be used under reduced pressure. This is particularly suitable for low-pressure or vacuum applications, such as mass spectroscopy. Ferrocene sublimes under reduced pressure at approximately 100°C, although its melting point is 173°C. For sulfones, sublimation begins at approximately 25°C and increases significantly above 60°C.

[0033] Alternatively, sulfoxide, especially dimethyl sulfoxide (DMSO), can be used.

[0034] In one embodiment, a solid is used that is not a sulfone, in particular not a dimethyl sulfone. In one embodiment, a solid is used that is not a solid sulfone, in particular not a solid dimethyl sulfone. In one embodiment, the operating agent is not a sulfoxide, in particular not a dimethyl sulfoxide.

[0035] In one embodiment, the operating medium is arranged in a particularly replaceable storage unit. Replaceable means that a used or emptied storage unit can be removed from the device in order to replace it with a new or filled storage unit, for example, in the manner of a printer cartridge. This enables simple and quick refilling of the operating medium. The storage unit can be arranged upstream of the device and / or upstream of the particle counter. In one embodiment, a heating device for heating the carrier gas is arranged directly upstream of the contact point with the operating medium, for example, the storage unit. Typically, the storage unit is arranged downstream of a heating device for heating the carrier gas.

[0036] In particular, the storage unit and / or the device is designed such that a carrier gas and / or the aerosol containing the particles to be enlarged and / or a separate gas stream can be guided through the storage unit or around the storage unit. In this case, the carrier gas can come into contact with the operating medium.

[0037] A storage unit is particularly well-suited for accommodating a solid operating fluid. In the case of a solid operating fluid and a heated carrier gas stream, the operating fluid, particularly its uppermost layer, sublimates due to the heated carrier gas or otherwise transitions into the gas phase. Surfaces on or in the storage unit should be smooth, for example, polished. Edges on or in the storage unit should be rounded and, in particular, smooth. This prevents unplanned deposition of operating fluid.

[0038] A layer of the operating medium on or in the storage unit preferably has a thickness of less than 3 cm, in particular less than 1 cm, and in one embodiment less than 0.5 cm or less than 0.2 cm. The layer thickness is in particular greater than 1 μm.

[0039] In one embodiment, the storage unit is designed as a cartridge. A cartridge is a container in which a substance such as an operating medium can be held; the container can be completely closed. However, this is not absolutely necessary. In particular, the cartridge is replaceable. When the operating medium is used up, the operating medium can be easily refilled by exchanging the empty cartridge for a filled one. In particular, the cartridge is designed so that a carrier gas can be passed through the cartridge. In one embodiment, the cartridge and / or the operating medium arranged in the cartridge contains a through-opening through which a flow of the carrier gas can be passed. The through-opening then acts as a flow path for the carrier gas.

[0040] In principle, the cartridge can be shaped as desired. In one embodiment, the cartridge comprises a tubular section or is designed as such. The tubular section can be straight. A tubular outer wall of the cartridge can then contain the operating medium. In this case, the operating medium can serve as an inner wall for a gas stream flowing through it. The operating medium is located in particular as a layer inside the cartridge and / or inside the outer wall. A central through-opening can be formed along the longitudinal axis of the tube as a flow path for the aerosol. This embodiment is particularly simple and cost-effective to produce. Alternatively or additionally, the operating medium can be arranged on the outside of an installation in the cartridge. A gas stream can then flow around such installations in order to bring the operating medium into the gas phase.

[0041] In one embodiment, the cartridge is curved or spiral-shaped. For example, a tubular section of the cartridge is curved or spiral-shaped. This allows a longer path and potentially a larger surface area to be provided with a small cartridge volume.

[0042] In the simplest case, the cartridge only needs to allow contact between the carrier gas and the operating fluid. A perforated wall can also be present between the operating fluid and the flow-through interior of the cartridge. The cartridge can therefore be designed as a double-walled tube, with the operating fluid between the walls and the inner wall having passages.

[0043] If a solid operating medium is present, this can be brought into the gas phase by heating the cartridge. In one embodiment, the cartridge is heatable. For example, the cartridge comprises an outer wall, preferably made of a material with good heat conduction, such as a metal such as copper. The operating medium can be arranged inside the outer wall. The outer wall is designed in particular such that a heat source positioned outside the outer wall can heat the operating medium through the wall. In particular, the device comprises a heat source which is designed to heat the cartridge located in the device. The heat source is designed in particular such that it is arranged outside the outer wall of the cartridge and can heat the outer wall, such that the operating medium can be heated through the outer wall.Alternatively or additionally, the heat source can be part of the cartridge, wherein the heat source can be designed as described. Alternatively or additionally, the cartridge, in particular a wall of the cartridge itself, can be inductively heated. In one embodiment, the cartridge can be heated only in some sections, in particular with respect to the longitudinal extent of the cartridge or the tube, and / or can be heated differently in different sections. In this way, different temperatures can be achieved in different sections. Different sections of the cartridge or the tube can be composed of separate components and / or thermally insulated from one another. The heating device can be configured to achieve different temperatures in different sections of the cartridge. In this way, the solid operating medium can be sublimated or brought into the gas phase.

[0044] In one embodiment, the storage unit is designed as a single unit or as a plurality of units that can be inserted, in particular interchangeably, into a flow path of a device. The flow path can be a flow path for the aerosol and / or for a carrier gas.

[0045] For example, an installation can be designed as a rod, preferably made of metal, with a layer of the operating fluid on its outer wall. The wall can be made of a material with good thermal conductivity, such as copper. Such an installation can be inserted into a flow path of the device from the outside at a suitable interface and typically secured there. This allows for easy installation and removal.

[0046] Alternatively, the installation can comprise an element consisting entirely of the operating medium, for example, in the form of a rod. The installation then typically includes a mounting unit on which the element from the operating medium is arranged. The mounting unit can then be attached to or in an interface of the device in such a way that the element protrudes from the operating medium into the flow path and can be flowed around there.

[0047] An installation such as a rod can contain a heat source inside. This can be, for example, a resistance-based or inductive heating device, or even a heat exchanger through which a heating medium can be passed. Alternatively or additionally, the mounting unit can be heated. In this way, heating can be achieved easily to bring the operating medium into the gas phase.

[0048] In one embodiment, a second storage unit is arranged downstream of the operating medium. The second storage unit is designed to hold the operating medium. Typically, the second storage unit is unloaded, i.e., it contains no operating medium. The second storage unit is intended to be loaded with operating medium. It can then be used as a storage unit when the storage unit with the operating medium has been used up. For example, it can be exchanged for the storage unit. Operating medium in the gas phase can therefore accumulate in the second storage unit as a solid phase, e.g., resublimate, as it flows through the second storage unit. In particular, the second storage unit is cooled or can be cooled. The second storage unit can be cooled from the inside or outside, actively or passively. In this way, excess operating medium can be captured and reused.A cycle can be established in which the operating resource only needs to be replenished very rarely.

[0049] The second storage unit can be arranged at any location downstream of the point where the operating medium transitions into the gas phase, for example, where an air stream comes into contact with the operating medium, e.g., downstream of the storage unit containing the operating medium, in particular a solid one. The second storage unit can be constructed in the same way as the storage unit containing the operating medium, for example, as a cartridge or built-in. In this regard, reference is made to the descriptions of the storage unit. The wall of the second storage unit is, in particular, roughened. This ensures that the deposition is effective, especially initially.

[0050] In one embodiment, the storage unit is designed as a particularly heated insert, e.g., a rod, and / or the second storage unit is designed as a particularly cooled cartridge. In one embodiment, the storage unit is designed as a particularly heated cartridge and / or the second storage unit is designed as a particularly cooled insert, e.g., a rod. An insert can be cooled from the inside and / or via a fastening unit.

[0051] In one embodiment, the enlarged particles are optically detected. In one embodiment, a number of particles is determined. In one embodiment, after the particles of the aerosol have been enlarged, at least one property of the aerosol is optically determined. A condensation particle counter can be used to determine the number, or the determination can be carried out in the manner of a condensation particle counter, e.g., with an optical detection unit of a condensation particle counter. The number of particles can be determined, for example, using scattered light. The quality of the growth or activation can be determined using the intensity of the scattered light. The optical determination can, for example, be a detection of a number of particles, for example in a specific volume and / or a specific time interval. The optical determination can also be an optical detection of a property of one or more particles.In this way, the size of a particle and / or the average size of several particles can be determined. A size typically refers to a diameter. Preferably, a number concentration of the particles can be determined. A number concentration, an absolute number, a number per time and / or per volume, and / or a mass concentration can be determined.

[0052] After the particles have been enlarged, a gas volume or gas stream with enlarged particles is typically present. In one embodiment, the gas volume or gas stream is irradiated with light, in particular by means of a focused light source such as a laser. A device for enlarging particles can comprise such a light source. A laser can have a wavelength of 405 nm or 655 nm. In one embodiment, an optical detector is present for detecting the enlarged particles. In one embodiment, the detector is configured to detect scattered radiation. For example, a light trap can be present, in particular opposite the light source. A photodetector can be present, for example a photomultiplier PMT. This can be arranged offset by 90° to the plane between the light source and the light trap and / or in the center of the light scattering point.In particular, evaluation electronics are provided to determine the number, concentration, size information based on the intensity of the scattered light, or number concentration of the particles from the signals received from the detector. For example, the evaluation electronics are configured to count the number of particles, for example, in a specific time interval. In one embodiment, the evaluation electronics has access to information on a volume flow or volume of the gas.

[0053] In particular, the process is continuous. A carrier gas stream is brought into contact with the operating fluid.

[0054] In one embodiment, a stream of supersaturated vapor is mixed with a stream containing the particles. The stream containing the particles, in particular, contains no operating fluid. The supersaturated vapor, in particular, contains no particles. In this way, the maximum supersaturation for particle activation can be controlled or adjusted, and / or the radius of the smallest activatable particles can be influenced. For example, a particle size distribution of particles smaller than 120 nm can be determined in this way. The mixing ratio can be selected and / or modified according to requirements.

[0055] If the proportion of supersaturated steam is low, there is less operating fluid available to attach to particles. Accordingly, only larger particles are activated to a size that allows them to be detected. With a higher proportion of supersaturated steam, the detection threshold drops, so that even smaller particles are activated for detection. If the proportion of supersaturated steam is sufficiently high, all particles are activated accordingly. In this way, different thresholds can be set specifically. This allows more information about the particles to be obtained. For example, by subtracting the difference, the proportion of particularly small particles and / or the size distribution of the initial particle population can be determined.

[0056] In one embodiment, the particles are magnified and the enlarged particles are optically detected in a first phase. In a second phase, particles of the aerosol are optically detected without magnification. The first and second phases follow one another in any order.

[0057] Typically, the first phase involves determining the number and / or concentration of particles. Preferably, the second phase involves determining the particle size distribution. The order of the phases is irrelevant. The functions of a condensation particle counter and a particle spectrometer are thus possible in different modes of a single process or device. This provides additional functionality. A corresponding device can be referred to as a particle spectrometer / counter.

[0058] In the second phase, downstream of the magnification, detection takes place, for example, in a particle spectrometer. To determine the particle size, no activation of the particles is required, so no operating fluid is required. Continuous operation is possible. Thus, the total concentration or total number concentration, as well as reliable information on the particle size, can be determined in a very short time.

[0059] It is possible to carry out the two phases directly one after the other. Preferably, the time between the end of one phase and the beginning of the other is less than 90 seconds, in particular less than 60 seconds, preferably less than 40 seconds or less than 30 seconds. In one embodiment, the time between the two phases is less than 20 seconds, in particular less than 10 seconds. In other words, the concentration and particle size distribution are measured sequentially and in rapid succession. Activation occurs only when required to determine the total number of particles, some of which are very small.

[0060] Switching between phases can be achieved by selectively heating the carrier gas, thereby enabling or disabling particle activation. In the simplest case, switching between phases can be achieved by switching a heating device on or off. Such rapid switching between a phase in which particles are activated and a phase in which particles are not is only possible through the use of a carrier gas. It has been shown that after a very short time - as mentioned above - the current measurement is no longer influenced by the previous phase. This advantage is particularly significant, as the time required for switching is particularly short, when a fixed operating medium is used.

[0061] Tests have shown that a solid operating agent does not affect the aerosol in the second phase. Therefore, the particle size distribution can be measured without interference, even if a solid operating agent is present in the aerosol or carrier gas.

[0062] In one embodiment, in a first phase the carrier gas is heated to a first temperature and in a second phase the carrier gas is heated to a second temperature different from the first temperature.

[0063] In one embodiment, in a first phase, a supersaturated vapor having a first temperature is generated, and in a second phase, a supersaturated vapor having a second temperature different from the first temperature is generated.

[0064] The two phases follow one another in any desired chronological order. These configurations make it possible to generate different vapor pressures. This also makes it possible to specifically achieve different limit values ​​or cutoffs. Depending on the temperature, particles of a certain size are just (sufficiently) activated to be captured or detected, while smaller particles can no longer be captured. The different phases lead to different supersaturations of the vapor and thus to different limiting particle sizes of particles that can just be detected. The production of supersaturated vapor at a specific temperature can be achieved, for example, by heating or cooling the saturated or supersaturated vapor. Saturated vapor can be cooled to produce supersaturated vapor.If a solid is used as the operating medium, cooling to room temperature is usually sufficient.

[0065] Saturated or supersaturated vapor can be cooled actively. This involves active cooling. In particular, an object in contact with the saturated vapor, such as a wall, is cooled directly or indirectly. Alternatively or additionally, cooling can be passive. Cooling occurs through the influence of the ambient temperature. For example, the vapor can be passed through a sufficiently long pipe so that the temperature of the vapor in the pipe drops sufficiently. Alternatively or additionally, the temperature can be kept constant.

[0066] In one embodiment, a wall in contact with the carrier gas is heated to heat the carrier gas. The wall can be the wall of a tube or vessel containing the carrier gas and / or through which the carrier gas flows. Heating can occur, for example, inductively and / or resistance-based. Direct heating of the wall can occur, for example, inductively. This allows particularly rapid heating or switching between heating and non-heating. Indirect heating can occur, in which a heating element is heated, which heats the wall. The wall can be a wall of a heat exchanger or heating element for heating the carrier gas. For example, lines with a hot medium and / or heating elements can be present in a space provided for the carrier gas.

[0067] In one embodiment, the carrier gas is heated to a temperature between 30°C and 100°C. In one embodiment, the carrier gas is heated to a temperature of at least 20°C, in particular at least 30°C, preferably at least 35°C and / or at most 150°C, in particular at most 100°C, preferably at most 90°C, typically at most 80°C, for example at most 60°C, preferably at most 50°C and in one embodiment at most 40°C. The carrier gas is typically heated to at most just below the melting temperature of the solid operating medium. In one embodiment, the aerosol is selected from ambient air, combustion exhaust gas, production exhaust gas, supply air of a clean room, exhaust air of a clean room, supply air of a substantially enclosed space and exhaust air of a substantially enclosed space.A cleanroom can, for example, be a cleanroom in the chemical industry, the pharmaceutical industry, chip production, a hospital, or a laboratory, such as an S0, S1, S2, S3, or S4 laboratory. The supply air of a cleanroom can be analyzed for monitoring purposes. The exhaust air of a cleanroom can be a separate air stream extracted for detection (room air monitoring) or an independently present exhaust air stream for ventilating the cleanroom. Exhaust air from the cleanroom can be analyzed for the purpose of monitoring the condition or contamination of the cleanroom. Production exhaust gas can, for example, originate from industry, medicine, medical technology, pharmaceuticals, chemistry, or a military application.In particular, the method or use can be used to determine dust and / or aerosol exposure, optimize a process, analyze combustion residues, monitor quality, investigate climate relevance, investigate particle pollution, avoid a hazard, assess a risk, and / or control production. Ambient air means, in particular, air from a specific region of the Earth's atmosphere. In the case of combustion exhaust gas, this can be the exhaust gas from an internal combustion engine such as a diesel or gasoline engine. This can occur during engine development, combustion optimization, and / or the technical monitoring of engines or vehicles. It can be an internal combustion engine of a motor vehicle, aircraft, ship, or rail vehicle.In particular, the particle number or a value derived from it such as the particle number concentration, which corresponds to the particle number per volume, the particle number per time or the particle number per time and power can be used.

[0068] A substantially enclosed space can be a passenger compartment, e.g., an aircraft cabin. Here, the quality of supply and / or exhaust air can be measured to determine and / or adjust the cabin air quality.

[0069] In one embodiment, the aerosol contains lipophilic and / or insoluble particles. Insoluble particles can include, for example, silicates and / or mineral dusts. According to the invention, lipophilic particles can be enlarged just as well as hydrophilic particles. The lipophilic particles can be hydrophobic. In one embodiment, the aerosol contains hydrophilic particles. The hydrophilic particles can be lipophobic. In one embodiment, the aerosol contains lipophilic and hydrophilic particles. In one embodiment, the aerosol contains organic particles. Any combinations are possible. In one embodiment, essentially all of the particles of the aerosol are lipophilic and / or hydrophilic.

[0070] In one embodiment, the particles are magnified at an altitude of more than 500 m above the earth's surface and / or from an aircraft. The altitude is preferably more than 1,000 m, in one embodiment more than 5,000 m above the earth's surface, and / or less than 20,000 m, in one embodiment less than 15,000 m above the earth's surface. Additionally or alternatively, the magnification takes place in or on an aircraft. In particular, the particles are also counted at the aforementioned altitude. In this way, aerosols present at different altitudes in the atmosphere can be examined. Since applications in a high vacuum are also possible, the particles can also be magnified at greater altitudes. For this reason, no altitude limitation is necessary.

[0071] In one embodiment, the particles are detected in a mass spectrometer. For example, the particles are selected or sorted depending on their charge in an electric field and / or based on their inertia. In this way, for example, particles that are positively or negatively charged can be selectively magnified. This can be done in a low-pressure or vacuum environment, as described elsewhere.

[0072] In one embodiment, the contact between the particles and the supersaturated vapor and / or the contact between the carrier gas and the operating fluid occurs at a negative pressure. For example, the pressure is below 200 hPa, in particular below 60 hPa, and preferably below 5 hPa. This can occur, for example, at high altitudes and / or enable the use of certain operating fluids.

[0073] A further aspect of the invention is the use of a heated gas or carrier gas to produce a supersaturated vapor. The heated gas or carrier gas comes into contact with a working medium. In this way, a supersaturated vapor is preferably produced. The supersaturated vapor comes into contact with the particles in order to enlarge the particles of an aerosol. All features, embodiments, and advantages of the method described above can also apply to the use, and vice versa. A further aspect of the invention is the use of a solid working medium to produce a supersaturated vapor. Typically, the supersaturated vapor comes into contact with the particles in order to enlarge the particles of an aerosol. All features, embodiments, and advantages of the method described above can also apply to this use, and vice versa.

[0074] A further aspect of the invention is a device for enlarging particles of an aerosol. The device comprises a heating device for heating a carrier gas to produce a supersaturated vapor and a condenser for enlarging particles of an aerosol using the supersaturated vapor. All features, configurations, and advantages of the method and use described above can also apply to the device, and vice versa.

[0075] In one embodiment, the device comprises a storage unit, particularly a replaceable one, containing a fixed operating medium. In particular, the storage unit is designed as a cartridge through which the aerosol containing the particles to be enlarged and / or a carrier gas can be passed. Alternatively, the storage unit can be designed as a built-in unit.

[0076] In one embodiment, the device comprises a further heating device for adjusting the temperature of a partial flow, a carrier gas, the saturated vapor, and / or the supersaturated vapor. Several further heating devices may be present. In particular, each heating device can be operated independently of the other heating device(s).

[0077] In one embodiment, the device comprises a control device which is configured to selectively switch heating of the carrier gas on and off or to selectively set a temperature of the carrier gas or of the supersaturated vapor to a specific value. The activation of the particles can be selectively switched on or off. In this way, a number or number concentration as well as information on the grain size of the particles can be obtained in a short time and optionally immediately one after the other. Alternatively or additionally, the temperature can be set so that a specific cutoff can be specifically set. The control device is in particular connected to one or more heating devices in such a way that it can automatically set a temperature of the respective heating device. In particular, the temperature of the respective heating device can be regulated to a specific value.In particular, the particles grow to a particle size of at least 500 nm, preferably 1 pm.

[0078] A further aspect of the invention is a device for enlarging aerosol particles. The device comprises a fixed operating medium for producing a supersaturated vapor and a condenser for enlarging aerosol particles using the supersaturated vapor. All features, configurations, and advantages of the method and use described above can also apply to the device, and vice versa.

[0079] A further aspect of the invention is a storage unit with a solid operating medium for enlarging particles of an aerosol and / or for use in a device for enlarging particles of an aerosol. The device can be a device according to the invention. The storage unit can be, for example, a cartridge or an installation. All features, properties, and advantages of the above-mentioned method and of the above-mentioned device also apply to the cartridge and vice versa. A storage unit can be filled with molten or liquid operating medium and / or with powdered operating medium or, as described above, by deposition from the gas phase.

[0080] Below, exemplary embodiments of the invention are explained in more detail with reference to the figures. Features of the exemplary embodiments can be combined individually or in multiples with the claimed subject matter, unless otherwise stated. The claimed scope of protection is not limited to the exemplary embodiments.

[0081] They show:

[0082] Figure 1 : an experimental setup,

[0083] Figure 2: Vapor pressure curves,

[0084] Figure 3: a schematic structure of a condensation particle counter,

[0085] Figure 4: a schematic structure of another

[0086] Condensation particle counter,

[0087] Figure 5: a schematic structure of another

[0088] Condensation particle counter,

[0089] Figure 6: a cross-section of a cartridge according to the invention, Figure 7: a view of a cartridge according to the invention,

[0090] Figure 8: a device for enlarging particles,

[0091] Figure 9: another device for enlarging particles,

[0092] Figure 10: another device for enlarging particles,

[0093] Figure 11 : Measurement results of a first test phase,

[0094] Figure 12: Measurement results of a second test phase,

[0095] Figure 13: Measurement results when switching a device; and

[0096] Figure 14: a schematic structure of another

[0097] Condensation particle counter.

[0098] Figure 1 shows a test setup for investigating a condensation particle counter 21 with an aerosol 2 produced for experimental purposes for the evaluation of different operating materials. The aerosol 2, which contains the particles 1, is produced in an aerosol source 10, e.g., a Nebulizer TSI:3076, and then passed through a dryer 12 and a regulation of excess air 13, first into a size selection 14. Preferably, a differential mobility analyzer (DMA) is used, which only allows particles of a specific size to pass through, thus generating a monodisperse aerosol.

[0099] In addition, soot particles produced by a soot generator 11 can also be fed to the size selection stage 14. The aerosol is fed into the mixing chamber 22, which is part of a low-pressure region 23, via an opening 18 and a line. The line is connected to a flow controller 15 via a particle filter 16 and a mass flow controller 17. Furthermore, a humidity controller 24 is provided to influence the humidity in the mixing chamber 22. Above the humidity controller 24 is a device for diluting and / or pressure controlling the atmosphere in the mixing chamber 22. Both devices are each connected to the mixing chamber 22 via a mass flow controller 17 and a particle filter 16. A temperature controller for the mixing chamber 22 is also provided.

[0100] Several measuring instruments are connected to the mixing chamber 22 via an outlet line: a reference measuring instrument 19 for determining the number concentration, for example, a Faraday Cup Electrometer; a conventional condensation particle counter 20 with an operating medium such as 1-butanol, for example, Grimm 5.411 or TSI 3772CEN; and the condensation particle counter 21 with the device according to the invention. The desired pressure in the low-pressure region 23 is achieved with a pump shown on the right.

[0101] Soot particles are hydrophobic and lipophilic and insoluble in water. The particles generated with the nebulizer are particularly hydrophilic and lipophobic. Using both devices, different aerosols and, if necessary, mixtures can be examined.

[0102] Figure 2 shows vapor pressure curves for the operating fluids dimethyl sulfoxide (DMSO 32), butanol 33, water 34, and dimethyl sulfone (DMS 52). The vapor pressure p in bar is plotted on a logarithmic axis against the temperature T in °C. Since the vapor pressure of DMSO 32 is an order of magnitude lower than that of butanol 33, the loss of operating fluid and thus the consumption is significantly reduced in the case of DMSO 32. This reduction has been confirmed experimentally. The same applies to the operating fluid dimethyl sulfone 52, which can be used as a solid. Furthermore, since the curves for butanol 33 and DMSO 32 run parallel, the supersaturation is similar at the same temperature difference between the saturator and the condenser. For this reason, DMSO 32 behaves similarly as an operating fluid to butanol 33.

[0103] Figure 3 shows a device 31 according to the invention and / or a device 31 for carrying out the method according to the invention. Following an inlet 25 for supplying the aerosol 2 containing the particles 1, there is a heating device 42 for heating the carrier gas. The heating device 42 is designed as a heated tubular element 59. The wall of the tube is heated from the outside. This is followed by a saturator 27 for producing a non-supersaturated vapor 4 using the heated carrier gas. Located in the saturator is a humidifier 36, which is designed, for example, as a sponge or similar component with a large surface area. The humidifier 36 can be arranged on one or more walls inside the saturator 27 and / or spaced from walls in the interior of the saturator 27. A storage container 30 containing a typically liquid operating medium 35 is connected to the humidifier 36 to produce the non-supersaturated vapor 4.For this purpose, the operating medium 35 evaporates at the humidifier 36 at a first temperature, which is typically below the boiling temperature of the operating medium 35 used.

[0104] The gas stream is then cooled to produce the supersaturated vapor 3. This occurs in a condenser 28 to enlarge particles 1 of the aerosol 2. The supersaturated vapor 3 comes into contact with the particles 1 of the aerosol 2, which subsequently grow. An optical system 29 is arranged between the condenser 28 and the outlet and serves to detect the particles. The particles can be counted via evaluation electronics connected to the optical system 28. In particular, the device 31 comprises the evaluation electronics. The device 31 can be designed as a condensation particle counter.

[0105] Particle growth is shown schematically. While in the saturator 27, the size of particles 1 only increases slowly up to the equilibrium radius, with increasing residence time in the condenser 28, the particles grow rapidly over several orders of magnitude in non-equilibrium (activated), so that enlarged particles 5 with an increased diameter are formed.

[0106] Figure 4 shows another embodiment of a device 31. To avoid duplication, only differences from the device in Figure 3 are described. The device 31 comprises a replaceable storage unit in the form of a cartridge 40 containing a solid 43 as the operating medium, for example, a solid sulfone. The cartridge 40 can be mechanically connected to the rest of the device 31. The connection points for this purpose are schematically shown as gaps. The cartridge 40 serves in particular as a saturator 27 or as a part thereof.

[0107] In one embodiment, the device 31 contains one or more flow paths 41 for the aerosol 2. A flow path 41 of the device 31 can have an outflow interface 45 for transferring the aerosol 2 into the cartridge 40 and / or an inflow interface 46 for transferring the aerosol 2 from the cartridge 40. In one embodiment, the cartridge 40 contains an inlet opening

[0108] 48 for introducing the aerosol 2 obtained from the outflow interface 45 into the cartridge 40. In one embodiment, the cartridge 40 contains an outlet opening

[0109] 49 for dispensing the aerosol 2 from the cartridge 40 into the inflow interface 46 of the device 31.

[0110] The condenser 28 and / or the optics 29 can be designed as shown in Fig. 3. Here, too, the particle growth is shown schematically.

[0111] In contrast to Figure 4, the solid operating medium can also be arranged in a permanently installed part of the device 31, for example a correspondingly designed pipeline, i.e. without a replaceable cartridge 40. Figure 5 shows a further embodiment of a device 31 which is constructed similarly to Figure 4. Here too, only differences are discussed to avoid duplication. The device 31 comprises a heating device 42 for directly or indirectly heating the cartridge 40 or the solid 43 located therein. Furthermore, as shown in Figure 4, a heating device for heating the carrier gas can be provided. This is not necessary, however. It is therefore also possible to heat a solid 43 directly or indirectly without heating the carrier gas, for example by heating the cartridge. Here too, a permanently installed part of the device 31 can be equipped with the operating medium instead of the cartridge.

[0112] Figure 6 shows a cross-section through a storage unit according to the invention in the form of a cartridge 40. The cartridge 40 comprises a tube 50 with an outer wall 51. The wall 51 can be made of a metal. A solid 43 is arranged on the inside of the outer wall. This is designed, for example, as a continuous and / or circumferential layer with a substantially constant thickness. The layer thickness can, as shown, be less than the thickness of the wall or can be the same thickness or thicker. The layer thickness is a measure of the fill level of the cartridge 40 with the solid operating medium or of the remaining capacity of the cartridge 40. The circular cross-section shown in Figure 7 is advantageous because such a cartridge can be installed in an existing particle counter and used with it without modifications. In principle, however, any other shapes are also possible. In particular, internal parts of the storage unit orthe cartridge and / or the storage unit, the downstream surfaces of the flow path are rounded, smooth and / or polished to ensure that there are no sharp edges where unplanned resublimation could occur.

[0113] Figure 7 shows a schematic longitudinal section through a cartridge 40. A heated tubular element 59 serves to supply the particularly heated carrier gas into the interior of the cartridge 40. The tubular element can be extended into the interior of the cartridge 40, as shown. The generated vapor can be guided to the optical particle counter 55 through another tubular element.

[0114] The cartridge 40 can have rounded edges and / or corners. This prevents unwanted deposits, for example due to resublimation. The cartridge 40 can comprise flow elements 58 that have a gradient to avoid turbulence. For example, as shown, in the region of the edges of the cartridge, in particular circumferentially, there can be an obliquely arranged flow element 58 that is arranged at an angle of 0° to the vertical. The vertical is perpendicular to the main flow direction through the cartridge 40. The angle is typically more than 3°, in particular more than 5° and / or less than 60°, in particular less than 30°, for example than 10°, preferably approximately 7°.

[0115] In particular, a heated tubular element for heating the carrier gas has a smaller diameter than the cartridge. A small diameter of the heated tubular element enables particularly rapid switching between a phase with and without particle activation.

[0116] Figure 8 shows an embodiment of a device according to the invention. A distributor is provided which divides an inflow of gas to be analyzed containing the aerosol into two partial streams. In the first partial stream, a heating device 42 is provided, with which the carrier gas, which also contains particles to be enlarged, can be heated. The operating medium 35 is then brought into the gas phase. A fixed operating medium 35, for example in a storage unit, can be contacted. An optional second heating device 42 can be provided. This can, for example, keep the flowing gas at a preset temperature between the ambient temperature and the temperature of the first heating device 42 in order to enable a certain supersaturation. If this is changed, a different limiting particle size can be set, which can then be activated.

[0117] A pump 53 is provided in the second partial stream to pump the gas. A particle filter 54 is located downstream of the second partial stream. This allows a particle-free stream to be generated. The two partial streams can be recombined via a subsequent mixer, particularly in the desired ratios. The combined stream can then be directed to an optical particle counter 55. A critical nozzle or a mass flow controller can be provided downstream to maintain a constant flow. This embodiment allows dilution of the particle stream under investigation.

[0118] Figure 9 shows a further embodiment of a device according to the invention. The gas stream to be analyzed is also divided. The first partial stream can correspond to the first partial stream from Figure 8. Typically, no change in the gas occurs in the second partial stream. Both partial streams lead to a common three-way valve 56. This allows switching between the first and second partial streams. Thus, measurements can be performed sequentially in different phases, during which – when using the first partial stream – the particles are activated and typically the total number or number concentration of the particles is determined, and – when using the second partial stream – a particle size distribution can be analyzed without particle activation. The measurement then takes place in the optical particle counter 55.Subsequently, a critical nozzle or a mass flow controller can also be present here to set a constant flow.

[0119] Figure 10 shows a further embodiment of a device according to the invention. Here, too, the gas stream to be analyzed is divided. A pump 53, a particle filter 54, a heater 42, and the contact point with the operating medium 35 are arranged in the first partial stream. Typically, no change in the gas occurs in the second partial stream. After the two partial streams are subsequently recombined, the measurement is performed in the optical particle counter 55. A critical nozzle or a mass flow controller can also be present here to set a constant flow. This embodiment allows mixing of activated and non-activated gas.

[0120] In Figures 8 to 10, the operating medium 35 can be arranged in a storage unit, such as a cartridge or a built-in unit. A cooling device can be provided downstream of the storage unit to recover the solid operating medium from the gas phase.

[0121] Figure 11 shows results from a condensation particle counter (CPC) and a variety of particle sizes from a portable optical particle spectrometer (POPS). The logarithmic axis shows the particle number NP for the CPC (CPC P / ml), the sum of all particle sizes of the POPS (POPS P / ml), and the individual particle size ranges of the POPS, which are given in nm. The measurement was performed in the second phase of a method according to the invention, in which particles were optically detected without magnification. The measurement was taken at a time t = 368 s after the start of the experiment.

[0122] It turns out that the sum of the CPC is more than an order of magnitude larger than the sum of the POPS. The POPS measures down to a particle size limit of approximately 125 nm, while the CPC measures down to a particle size of 5 nm or smaller. The difference is therefore due to particles smaller than 125 nm that are still detected by the CPC. It also shows that the particle size distribution is roughly constant between 130 nm and approximately 240 nm and decreases towards larger particles.

[0123] Figure 12 shows a similar diagram at a time t = 426 s after the start of the experiment, i.e. about 58 s after the diagram in Fig. 11. In the meantime, the system was switched so that here the measurement was taken in the first phase in which the particles are activated.

[0124] First, it is noticeable that no particles below 745 nm were detected, and all individual particle sizes lie between 745 nm and 2770 nm. It is also noticeable that the sums of the CPC and POPS are almost equal. Thus, all aerosol particles that can be measured by the CPC but not by the POPS could be enlarged by activation to such an extent that they were now also detected by the POPS.

[0125] Figure 13 shows a switch from the second phase to the first phase. It shows the number concentration NC of particles in 1 / cm 3 in logarithmic representation over time t in seconds. Similar to Figures 11 and 12, the results of a CPC and a POPS are shown. The CPC detects almost constant, but slightly decreasing, values ​​between 4000 / cm 3 and 3000 cm 3 The POPS initially continuously detects values ​​between 800 / cm 3 and 900 / cm 3Starting at a time t of 384 seconds, the detected values ​​increase sharply within 3 to 4 seconds and then essentially match the CPC values. It can be seen that switching is possible in just a few seconds according to the invention.

[0126] Figure 14 is based on Figure 5. Only the differences are discussed, and reference is made to the above description. In contrast to Figure 5, the storage unit in the embodiment shown here is designed as an installation 44 that contains the solid 43 or is at least partially made of it. The installation can be heated internally. Alternatively or additionally, the heating device 42 can heat the installation indirectly and / or heat the carrier gas directly or indirectly. Alternatively or additionally to the heating device shown here, the inflowing carrier gas can also be heated, as in Figures 3 and 4. List of reference symbols:

[0127] Particle 1 Aerosol 2 Supersaturated vapor 3

[0128] Non-supersaturated vapor 4 Enlarged particle 5 Aerosol source 10 Soot generator 11 Drying 12 Excess air 13 Size selection 14 Flow control 15 Particle filter 16 Mass flow controller 17

[0129] Opening 18 Reference measuring instrument 19 Condensation particle counter 20 Condensation particle counter 21 Mixing chamber 22 Low pressure area 23 Humidity control 24 Inlet 25 Outlet 26 Saturator 27 Condenser 28 Optics 29 Reservoir 30 Device 31 DMSO 32 Butanol 33 Water 34 Operating fluid 35 Humidifier 36 Particle count NP

[0130] Number concentration NC Temperature T Time t Vapor pressure P Cartridge 40 Flow path 41 Heating device 42 Solid 43 Installation 44 Outlet interface 45

[0131] Inflow interface 46 Inlet opening 48 Outlet opening 49

[0132] Pipe 50

[0133] Wall 51

[0134] Dimethylsulfone 52 Pump 53

[0135] Particle filter 54

[0136] Optical Particle Counter 55

[0137] Three-way valve 56

[0138] Flow element 58 Heated pipe element 59

[0139] Condensation particle counter CPC

[0140] Portable optical particle spectrometer POPS

Claims

Claims 1. Method for enlarging particles (1) of an aerosol (2), in which the particles (1) come into contact with a supersaturated vapor (3), wherein to produce the supersaturated vapor (3) a carrier gas is heated and then comes into contact with an operating medium (35).

2. Method according to the preceding claim, characterized in that a solid (43) is used as the operating medium (35).

3. Method according to one of the preceding claims, characterized in that the operating agent (35) is selected from a sulfone, e.g. dimethyl sulfone, camphor, iodine, naphthalene, a benzene compound, e.g. benzene acid, salicylic acid, ferrocene, anthracene, sulfur, dichlorobenzene, menthol, pyrene, benzenephenone, caffeine, arsenic, phthalic anhydride, a fullerene, and ammonium chloride.

4. Method according to one of the preceding claims, characterized in that the operating means (35) is arranged in an exchangeable storage unit.

5. Method according to one of the preceding claims, characterized in that a stream of the supersaturated vapor (3) is mixed with a stream containing the particles (1).

6. Method according to one of the preceding claims, characterized in that the enlarged particles (1) are optically detected in order to determine a number of particles (1).

7. Method according to claim 6, characterized in that in a first phase the enlargement of the particles (1) and the optical detection of the enlarged particles (1) takes place and in a second phase particles (1) of the aerosol are optically detected without magnification, wherein the first phase and the second phase follow one another in any desired order.

8. A method according to claim 6, characterized in that in a first phase the carrier gas is heated to a first temperature and in a second phase the carrier gas is heated to a second temperature different from the first temperature, or that in a first phase a supersaturated steam (3) is produced at a first temperature and in a second phase a supersaturated steam (3) is produced at a second temperature different from the first temperature.

9. Method according to one of the preceding claims, characterized in that a wall contacting the carrier gas is heated to heat the carrier gas.

10. Method according to one of the preceding claims, characterized in that the carrier gas is heated to a temperature between 30°C and 100°C.

11. Method according to one of the preceding claims, characterized in that the contact between the particles (1) and the supersaturated vapor (3) and / or the contact between the carrier gas and the operating medium (35) takes place at a pressure below 200 hPa, in particular below 60 hPa.

12. Device (31) for enlarging particles (1) of an aerosol (2), comprising a heating device (42) for heating a carrier gas to produce a supersaturated vapor (3) and a condenser (28) for enlarging particles (1) of an aerosol (2) by means of the supersaturated vapor (3).

13. Device (31) according to the preceding claim, characterized in that the device (31) comprises an exchangeable storage unit containing a fixed operating means (35), wherein the storage unit is designed in particular as - cartridge (40) through which the aerosol (2) with the particles (1) to be enlarged and / or a carrier gas can be passed, or as - Installation for insertion into a flow path.

14. Device (31) according to one of the preceding claims, characterized in that the device (31) comprises an unloaded second storage unit, wherein the second storage unit is arranged downstream of the point at which the operating medium (35) changes into the gas phase.

15. Device (31) according to one of the two preceding claims, characterized in that the device comprises a control device which is designed to selectively switch heating of the carrier gas on and off or to selectively set a temperature of the carrier gas or the supersaturated vapor (3) to a specific value.

16. Storage unit with a fixed operating means (35) for enlarging particles (1) of an aerosol (2), wherein the storage unit is designed in particular as - Cartridge (40) through which the aerosol (2) with the particles (1) to be enlarged and / or a carrier gas can be passed, or as an installation for insertion into a flow path.

Images