Method, use, device and cartridge for enlarging aerosol particles

Abstract

The invention relates to a method and to a device for enlarging particles of an aerosol, and to use of an operating medium for production of an oversaturated vapour. In a method of enlarging particles (1) of an aerosol (2), the particles (1) come into contact with an oversaturated vapour (3). The oversaturated vapour (3) is produced using a sulfoxide or a sulfone, for example dimethyl sulfoxide or dimethyl sulfone. These substances are nonflammable, not harmful to health and not hazardous to the environment, and are accordingly easy to handle. No odour nuisance or environmental damage occurs. The same numerical efficiencies for particles are achieved as with butanol, which is conventionally used as operating medium.

Description

[0001] Method, use, device and cartridge for magnifying aerosol particles

[0002] The invention relates to a method and a device for enlarging aerosol particles, a use of an operating medium for producing a supersaturated vapor and a cartridge.

[0003] Aerosol particles in the (lower) nanometer range cannot be easily detected optically. For optical detection of such particles, the particles must first be enlarged. In this process, the particles grow by approximately two orders of magnitude, for example, so that optical detection is subsequently possible. This can be the case in the 300 nm range, for example. The enlargement 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. A diffusive attachment of the vapor molecules to the particle occurs. The particles, enlarged or grown in this way, can then be detected using optical methods.

[0004] An aerosol is a mixture of solid and / or liquid particles in a gas. This gas is referred to as the carrier gas. The term "gas" as used in this application includes gas mixtures. The particles of an aerosol are also referred to as aerosol particles.

[0005] Technically, the particles are enlarged in a condensation particle counter (CPC), for example. The operating medium is brought to a constant temperature in liquid form. This takes place in a saturator through which a carrier gas flow flows. Depending on the temperature, a partial pressure of the operating medium, the saturation vapor pressure, is established in the carrier gas flow. The saturated carrier gas flow is fed into the condenser, which is cooler than the saturator. Due to the lower temperature, the partial pressure of the operating medium is now supersaturated. As soon as particles come into contact with this gas flow, they act as condensation nuclei and grow while adhering to the operating medium. An optical detector is used to detect the particles. For example, the gas flow can be irradiated with a focused light source, e.g., a laser.For example, radiation scattered by the particles can be detected. This allows individual particles and / or numbers or concentrations of particles to be detected.

[0006] Alcohols such as butanol, ethanol, or isopropanol are typically used as the operating fluid for producing the supersaturated vapor. However, alcohols are oxidizing and highly flammable, have a strong odor, and are harmful or toxic. Therefore, comprehensive safety precautions are required during handling and use. Furthermore, the maximum temperature of the saturator and thus the maximum achievable supersaturation are limited due to the low flash point and / or boiling point of these substances. This leads to a limitation of the lower detection limit, since the level of supersaturation determines the critical diameter of the particles that can still be activated.

[0007] Diethylene glycol (DEG) can also be used as a working fluid in special cases. It is capable of activating very small aerosol particles < 2 nm at a saturator temperature of 50-60°C. However, particles activated with diethylene glycol only grow to approximately 100 nm, necessitating additional activation in a downstream CPC. Furthermore, diethylene glycol is also harmful to health.

[0008] It is also possible to use fluorinated hydrocarbons such as perfluorotributylamine (PFTBA), which is available, for example, under the brand name Fluorinert. These are used in the low-pressure range below 300 hPa. However, PFTBA requires a high saturator temperature of 190°C, which limits its use to a few specialized applications. It is also harmful to health and highly polluting.

[0009] The above-mentioned features, effects and definitions may be combined individually or in a plurality with the claimed and described subject-matter.

[0010] 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 eliminated. This object is achieved by the method according to claim 1 and the use, the device, and the cartridge according to the independent claims. Advantageous embodiments are specified in the subclaims.

[0011] To solve this problem, a process is used to enlarge aerosol particles by bringing the particles into contact with a supersaturated vapor. A sulfoxide or a sulfone is used to produce the supersaturated vapor.

[0012] Many sulfoxides and sulfones are not classified with H-statements (hazard statements) or P-statements (precautionary statements) of the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). These substances are non-flammable, non-harmful to health, non-polluting to the environment, and therefore easy to handle. They do not cause unpleasant odors or environmental damage. Overall, this significantly reduces technical effort and simplifies particle enlargement. There are no restrictions regarding their use in sensitive areas. Accordingly, the process can also be used in passenger transportation, transport, aerospace, the automotive sector, medicine, clean rooms and laboratories, research, chemistry, biology, and the environmental sector.

[0013] Sulfoxides and sulfones have similar physicochemical properties to butanol, which has previously been frequently used to enlarge particles, particularly with regard to vapor pressure, diffusion properties, and operating temperature range. Therefore, these groups of substances are well suited to use supersaturated vapor to enlarge particles. They represent an alternative to the standard operating fluid 1-butanol and exhibit significantly improved properties. A further advantage is that conventional devices such as condensation particle counters or components thereof can be used to carry out the process according to the invention with little or no modification.

[0014] According to the invention, a sulfoxide or a sulfone is used to produce the supersaturated vapor. This is also referred to below as the operating agent(s) according to the invention. Another substance and / or a mixture of substances can also be used to produce the supersaturated vapor. In one embodiment, the supersaturated vapor is produced from a sulfoxide or a sulfone. The supersaturated vapor contains or consists of gaseous sulfoxide or sulfone.

[0015] Supersaturated vapor contains more gas particles than would be the case in thermodynamic equilibrium. Supersaturated vapor therefore has a higher density 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.

[0016] The particles come into contact with supersaturated vapor. Specifically, a non-supersaturated vapor is produced and converted into a supersaturated vapor by cooling. A non-supersaturated vapor can be saturated or non-saturated vapor. The particles or aerosol can already be present in the non-supersaturated vapor and, if necessary, be cooled with it. Cooling then converts the particle-containing non-supersaturated vapor into particle-containing supersaturated vapor. It is therefore not necessary for the particles to be introduced into the already supersaturated vapor.

[0017] Sulfoxides are a class of chemical compounds with organically bound sulfur and the general structure R 1 -S(=O)-R 2 , where R 1 and R 2organic residues. Sulfones are a class of compounds with organically bound sulfur and oxygen with the general structural formula R 1 -S(=O)2-R 2 , where R 1 and R 2 organic residues.

[0018] By selecting the organic residues, also known as ligands, the melting and / or boiling point of the respective substance can be influenced in both cases. This influences the vapor pressure. Thus, a suitable substance for specific requirements can be easily identified and used. It is possible to use a mixture of several sulfoxides, several sulfones, or at least one sulfoxide with at least one sulfone.

[0019] 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 supersaturated vapor is produced from dimethyl sulfoxide. In dimethyl sulfoxide (DMSO), the two organic residues are both methyl groups. Laboratory experiments and field studies have shown that enlarging the particles with this substance produces particularly good results. The counting efficiency of optical particle counters is equivalent to that of conventional butanol-operated particle counters. The same applies to the activation size, in particular the minimum (critical) activation size. DMSO is inexpensive, readily available, and due to its low vapor pressure, only a fraction of the operating fluid is consumed compared to, for example, butanol (approximately 10% of the consumption of butanol).

[0020] In one embodiment, the supersaturated vapor is produced from dimethyl sulfone. In dimethyl sulfone, the two organic residues are both methyl groups. This substance produces particularly good particle magnification results. The counting efficiency of optical particle counters is comparable to that of conventional butanol-powered particle counters.

[0021] Both sulfones and sulfoxides allow the use of organic radicals such as ethyl or cyclo compounds. Symmetric or asymmetric sulfones or sulfoxides can be used.

[0022] In one embodiment, 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. For example, it is d50. Growth or enlargement then takes place starting from this diameter.

[0023] It has been shown that even very small particles can be magnified using the device according to the invention. In particular, these particles can be optically detected after magnification.

[0024] In one embodiment, the supersaturated steam is produced by cooling non-supersaturated steam. In one embodiment, the non-supersaturated steam is produced at a temperature above 30°C, preferably above 40°C, in particular above 60°C.

[0025] The operating fluids according to the invention have high flash points and boiling points compared to previously used substances such as 1-butanol. Therefore, a higher temperature can be used with the invention. Butanol, for example, has a flash point of 35°C, so higher temperatures are not practical with this operating fluid.

[0026] The higher temperatures enable greater supersaturation and thus larger and faster growth. Ultimately, this allows for a particularly low detection limit (of the activatable particle size) to be achieved. These temperatures are particularly prevalent in a saturator.

[0027] A maximum temperature for DMSO can be 150°C, as thermal decomposition occurs above this temperature. When using other substances, the maximum temperature can be higher; for dimethyl sulfone, for example, it can be above 230°C. By selecting suitable organic residues, the maximum temperature can be adjusted within a wide range.

[0028] In one embodiment, the non-supersaturated vapor is produced at a temperature above 80°C, in particular above 110°C. In this way, a particularly low detection limit can be achieved, down to nanoparticles below 5 nm or below 2 nm, in particular without an additional activation stage. This can be achieved, in particular, at a condenser temperature of 5°C to 10°C.

[0029] In one embodiment, the supersaturated steam is produced by cooling non-supersaturated steam to a temperature below 20°C, in particular below 10°C. The temperature is in particular above 0°C or above 5°C. This target temperature can be set using particularly simple technical means.

[0030] In one embodiment, the supersaturated steam is produced by cooling non-supersaturated steam to room temperature and / or a temperature above 15°C, in particular 20°C and / or below 30°C, in particular 25°C. In many applications, this target temperature can be set entirely without technical means or at least without cooling. Cooling, for example by means of Peltier elements, can thus be dispensed with. If necessary, a heating device can be provided to increase the temperature as needed. Heating is technically much less complex than cooling. Due to the operating means according to the invention, a saturator temperature as low as in conventional devices is no longer necessary. Sufficient supersaturation can be achieved due to the higher saturator temperatures, even with higher condenser temperatures.

[0031] In one embodiment, a mixture of sulfoxide or sulfone with water is used to produce the supersaturated vapor. In particular, the sulfoxide or sulfone used to produce the supersaturated vapor is diluted with water. The use of water alone as a working medium is not possible due to its diffusion properties. However, it has been shown that a mixture of the working medium according to the invention with water leads to an effective enlargement of the particles. At the same time, different mixing ratios allow the melting point of the respective sulfoxide or sulfone to be adapted to the respective operating conditions or requirements.

[0032] The melting point of DMSO can be lowered from 18°C ​​to, for example, 5°C to 15°C by adding small amounts of water. For example, temperatures between 5°C and 15°C can prevail under the cockpit of an aircraft, where a particle counter can be operated to analyze atmospheric aerosols. When diluted with water, the particle counter can also be operated under these conditions without additional technical effort; for example, when diluted with 10% water by volume, it can be operated down to -10°C. There is then no risk of the operating fluid solidifying or freezing in storage containers or pipes.

[0033] In particular, the supersaturated vapor is produced from the sulfoxide or sulfone diluted with water. Typically, water is used as a diluent. In one embodiment, the volumetric proportion of water in the mixture is less than 10%. It has been shown that up to a water content of 10% in the total volume of the mixture, there is no significant impairment of the counting efficiency of a particle counter. In other words, reliable results are obtained up to this water content. In one embodiment, the water content is less than 5%. This allows for particularly accurate results. The water does not impair the particle size distribution.

[0034] In one embodiment, the particle enlargement occurs under negative pressure. In particular, the negative pressure is between 150 hPa and 750 hPa. Typically, the production of the non-supersaturated vapor and / or an optical determination also takes place under negative pressure. The pressure mentioned is an absolute pressure.

[0035] 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. 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. For example, a size of a particle and / or an average size of several particles can be determined. A size typically means a diameter. A number concentration of the particles can preferably be determined.

[0036] 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. In one embodiment, an optical detector is provided for detecting the enlarged particles. In one embodiment, the detector is configured to detect scattered radiation. In particular, evaluation electronics are provided for determining a number, concentration or number concentration of the particles from signals received from the detector. For example, the evaluation electronics are configured to count a number of particles, for example in a specific time interval. In one embodiment, the evaluation electronics has access to information about a volume flow or volume of the gas.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 room, and exhaust air of a substantially enclosed room. A clean room can be, for example, a clean room in the chemical industry, the pharmaceutical industry, chip production, a hospital, or a laboratory, for example an S0, S1, S2, S3, or S4 laboratory. The supply air of a clean room can be analyzed for monitoring purposes. The exhaust air of a clean room can be an air stream extracted separately for detection (room air monitoring) or an independently present exhaust air stream for ventilating the clean room. Exhaust air from the clean room can be analyzed for the purpose of monitoring the condition or contamination of the clean room. A production exhaust gas can originate, for example, from industry, medicine, medical technology, pharmacy, 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.

[0037] 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.

[0038] In one embodiment, the aerosol contains lipophilic and / or insoluble particles. Insoluble particles can include, for example, silicates and / or mineral dusts. Lipophilic particles can be enlarged just as well with the operating medium according to the invention 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.

[0039] In one embodiment, the particles are magnified at a height of more than 500 m above the earth's surface and / or from an aircraft.

[0040] 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 counting of particles also takes place at the specified altitude. In this way, aerosols present at different altitudes in the atmosphere can be examined. Due to current safety regulations, the use of butanol in passenger aircraft is practically no longer permitted. However, the operating means according to the invention still allow this.

[0041] A further aspect of the invention is the use of a sulfoxide or a sulfone to produce a supersaturated vapor. The supersaturated vapor comes into contact with the particles of an aerosol to enlarge them. In particular, a number of the enlarged particles is recorded using a particle counter. All features, advantages, and effects of the method described above apply accordingly to the use, and vice versa.

[0042] A further aspect of the invention is a device, in particular a part of a condensation particle counter or a condensation particle counter. This device comprises a condenser for enlarging particles of an aerosol using a supersaturated vapor. A reservoir for a sulfoxide or sulfone is provided to produce the supersaturated vapor. In particular, the reservoir contains the sulfoxide or sulfone. In particular, the condensation particle counter further comprises a saturator for producing a non-supersaturated vapor. All features, advantages, and effects of the method described above apply accordingly to the device, and vice versa.

[0043] In particular, the device or the condensation particle counter does not contain a cooling device for cooling the condenser. Since the higher saturator temperatures in the operating media according to the invention allow sufficient supersaturation to be achieved even with slightly higher condenser temperatures, cooling, for example, electrical cooling, can be omitted to simplify the device. This is reinforced by the fact that at low temperatures, the effects of temperature differences on the partial pressure of the operating media are small compared to high temperatures. Thus, no cooling elements, no fan, no associated control system, and no heat sinks for the warm side are required. Overall, the installation space of the device can be significantly reduced.

[0044] In one embodiment, the device is part of a condensation particle counter for analyzing combustion exhaust gases, in particular for the technical inspection of vehicles such as motor vehicles, aircraft, ships, and / or rail vehicles. In one embodiment, the device has a dso of 23 nm. The device can be a condensation particle counter according to the European Committee for Standardization (CEN).

[0045] 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.

[0046] They show:

[0047] Figure 1 : an experimental setup,

[0048] Figure 2: Counting efficiency curves,

[0049] Figure 3: a Kelvin-Köhler diagram,

[0050] Figure 4: Vapor pressure curves,

[0051] Figure 5: a schematic diagram of a condensation particle counter.

[0052] Figure 6: a schematic structure of another

[0053] Condensation particle counter, and Figure 7: a cartridge according to the invention.

[0054] 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, and then passed through a dryer 12 and a regulation of excess air 13, first into a size selection unit 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.

[0055] 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. A humidifier 24 is also provided to influence the air humidity in the mixing chamber 22. Above the humidifier 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.

[0056] Several measuring devices 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 condensation particle counter 20 with a conventional operating medium such as 1-butanol, and the condensation particle counter 21 with the operating medium according to the invention.

[0057] Soot particles are hydrophobic and lipophilic and insoluble in water. The particles generated with the nebulizer are particularly hydrophilic and lipophobic. By using both devices, different aerosols and, if necessary, mixtures can be analyzed. Figure 2 shows a diagram with curves for the counting efficiency of different operating media. In particular, the data shown were recorded using the device from Figure 1. The counting efficiency ECPC of the particle counter is plotted against the diameter d of the particles in nanometers. The diameter d is the mobility diameter measured using the DMA. The individual curves refer to a condensation particle counter B-CPC operated conventionally with butanol and an identical D-CPC operated with the operating media DMSO according to the invention. The counting efficiency was standardized in each case to the measured values ​​of the reference measuring instrument 19 (see Figure 1).With each of the CPCs, measurements were carried out under different negative pressures, namely 200 hPa, 500 hPa and 700 hPa.

[0058] It can be seen that there are no differences in the counting efficiency (ECPC) between the different operating media at any pressure level. It is also shown that the cutoff point, also referred to as the dso point, is 5.5 nm for both CPCs, regardless of the pressure used. Switching to the operating media according to the invention, illustrated here using DMSO as an example, therefore has no effect on the counting efficiency.

[0059] Figure 3 shows a Kelvin-Köhler diagram for the operating fluids DMSO 32, butanol 33, and water 34. The supersaturation ratio OR is plotted against the droplet diameter x of the respective operating fluid in pm. A NaCl particle with a diameter of 13 nm at 20°C was considered. The supersaturation ratio OR corresponds to the saturation quotient and is calculated as the quotient of the saturation vapor pressure over the curved surface of a particle and the saturation vapor pressure over a flat surface. The maximum of the curve defines the critical radius and the critical supersaturation. Once this point is exceeded, i.e., to the right of the respective maximum in the diagram, particles are activated and continue to grow continuously in a non-equilibrium state. Growth can thus occur over several orders of magnitude.

[0060] If the saturation quotient is greater than 1, supersaturation is present. For particles to grow, the saturation quotient must be above the respective curve; if it is below, the accumulated operating fluid evaporates. It turns out that when using DMSO 32, a supersaturation of 1.2% is required, while with butanol 33, only a supersaturation of 0.7% is required. It is also easily possible to achieve a supersaturation of 1.2% using commercially available CPC.

[0061] Figure 4 shows vapor pressure curves for the operating fluids DMSO 32, butanol 33, and water 34. The vapor pressure p in bar is plotted on a logarithmic axis against the temperature 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 other operating fluids according to the invention. Furthermore, since the curves for butanol 33 and DMSO 32 run parallel, the supersaturation is similar for the same temperature difference between the saturator and the condenser. For this reason, DMSO 32 behaves as an operating fluid similarly to butanol 33.

[0062] Figure 5 shows a device according to the invention and / or a condensation particle counter 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 saturator 27 for producing a non-supersaturated vapor 4. Located within the saturator is a humidifier 36, which is configured, for example, as a sponge or similar component with a large surface area. The humidifier can be arranged on one or more walls inside the saturator 27. A reservoir 30 containing an operating medium 35, namely a sulfoxide or sulfone, 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 point of the operating medium 35 used.

[0063] 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.

[0064] 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 comprises the evaluation electronics. Particle growth is shown schematically. While in the saturator 27, the size of the 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.

[0065] Figure 6 shows a device according to the invention and / or a condensation particle counter 31 for carrying out the method according to the invention. To avoid duplication, only differences from the device in Figure 5 are described. The device comprises a replaceable cartridge 40 containing a solid sulfone 43. The cartridge 40 can be mechanically connected to the rest of the device. The connection points for this purpose are schematically shown as gaps. The device can have a heating device 42 for directly or indirectly heating the cartridge 40 or the solid sulfone 43 contained therein. The cartridge 40 serves in particular as a saturator 27.

[0066] In one embodiment, the device contains one or more flow paths 41 for the aerosol 2. A flow path 41 of the device 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 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 49 for discharging the aerosol 2 from the cartridge 40 into the inflow interface 46 of the device.

[0067] The condenser 28 and / or the optics 29 can be designed similarly to Fig. 5. Here, too, the particle growth is shown schematically.

[0068] Figure 7 shows a cross-section through a cartridge 40 according to the invention. The cartridge 40 comprises a tube 50 with an outer wall 51. The wall 51 can be made of a metal. Solid sulfone 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 the same thickness or thicker. The layer thickness can vary in different sections of the tube 50, particularly with respect to the longitudinal extent of the tube 50. For example, a different layer thickness can be present in an inlet region of the tube than in an outlet region of the tube. The solid sulfone 43 has comparatively poor thermal conductivity, so that with a greater layer thickness, more energy is required for heating.Therefore, the layer thickness can be selected to achieve an optimum balance between energy efficiency and the service life of the cartridge 40, depending on the requirements. The layer thickness is also a measure of the fill level of the cartridge 40 with the solid sulfone or of the remaining capacity of the cartridge 40. The layer thickness and thus the capacity of the cartridge 40 can be indirectly determined via the heating or the energy required for this purpose. The circular cross-section shown in Figure 7 is advantageous because such a cartridge can be installed in and used with an existing particle counter without modification.

[0069] In one embodiment, a solid sulfone is used. This makes handling particularly easy.

[0070] In one embodiment, the device comprises a mixing device for producing a mixture of a sulfoxide and water. The mixing device can be designed such that predetermined amounts of sulfoxide and water are mixed in a flow to be fed directly to an evaporation device to produce the supersaturated vapor. The mixing can take place continuously, at least intermittently. The mixing device can be designed such that a mixing container is present into which predetermined amounts of sulfoxide and water are added. In this way, the mixture can be produced batchwise or in batches. The mixing device can be automatic and / or controlled by a controller. In this way, a suitable mixture can be produced automatically.

[0071] In an alternative or additional embodiment, the storage container is designed to hold a mixture of a sulfoxide and water.

[0072] If the supersaturated vapor is produced from the sulfoxide or sulfone diluted with water, the water can serve as an antifreeze.

[0073] In one embodiment, the volumetric proportion of water in the mixture is less than 60%, for example, approximately 46%. In one embodiment, the proportion of water in the mixture is less than 40 mol%, for example, approximately 30 mol%. Pure dimethyl sulfoxide (DMSO) has a melting point of 18°C. A mixture of, for example, dimethyl sulfoxide with water containing 30 mol% DMSO, corresponding to approximately 43 vol%, can lower the melting point to approximately -140°C. In this way, the invention can also be used at very low temperatures. This is advantageous, for example, for measurements in or on an aircraft or in the Antarctic. This opens up further areas of application.

[0074] In one embodiment, the reservoir is designed as a cartridge containing, for example, a solid sulfone. The sulfone can be, for example, dimethyl sulfone. The cartridge is particularly replaceable. This means that a used or empty cartridge can be removed from the device and replaced with a new or filled cartridge. The cartridge can be permanently installed or be present as a separate, mechanically detachable module. In the latter case, the cartridge can be arranged upstream of the device and / or upstream of the particle counter.

[0075] The cartridge can thus be replaceable like a printer cartridge. In particular, the cartridge and / or the device is designed so that the aerosol containing the particles to be enlarged can be guided through the cartridge. In one embodiment, the cartridge and / or the sulfone arranged in the cartridge contains a through-opening through which a flow of the aerosol can be directed. The through-opening then acts as a flow path for the aerosol. The aerosol can come into contact with the sublimated sulfone.

[0076] In one embodiment, the cartridge is heatable. In particular, the cartridge comprises an outer wall, preferably made of a material with good heat conduction, such as a metal such as copper. The sulfone can be arranged inside the outer wall. The outer wall is in particular designed such that a heat source positioned outside the outer wall can heat the sulfone through the wall. In particular, the device comprises a heat source that is designed to heat the cartridge located in the device. The heat source is in particular designed such that it is arranged outside the outer wall of the cartridge and can heat the outer wall, such that the sulfone can be heated through the outer wall. Alternatively or additionally, the cartridge can have a heat source, which can be designed as described.In one embodiment, the cartridge can be heated differently in different sections, particularly with respect to the longitudinal extent of the cartridge or tube. For example, different temperatures can be achieved in different sections. Different sections of the cartridge or 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.

[0077] For example, heating to a temperature of at least 35°C, in particular at least 40°C, preferably at least 50°C, particularly preferably at least 60°C, and / or at most 150°C, in particular at most 130°C, preferably at most 90°C, particularly preferably at most 70°C is provided. In other words, the cartridge and / or the device is configured such that such heating is possible.

[0078] It has been shown that a solid sulfone partially sublimes at a temperature of, for example, at least 35°C or 40°C and is suitable for enlarging aerosol particles through condensation. This type of solid sulfone has been shown to be easy to handle and very economical. No storage bottle, tubing, or porous material is required for evaporation. This type of solid sulfone can be used in existing condensation particle counters. Furthermore, the solid sulfone can also be used within the temperature range of existing condensation particle counters. The use of the solid sulfone in direct contact with the aerosol is particularly advantageous and simple. A cartridge containing the solid sulfone can be easily replaced and achieves reproducible results.

[0079] 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 sulfone. The sulfone is located in particular as a layer inside the cartridge and / or on the inside of the outer wall. The layer 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. 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.

[0080] 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 for a longer path to be provided with a small cartridge volume.

[0081] A further aspect of the invention is a cartridge with a solid sulfone 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 sulfone can be, for example, dimethyl sulfone. In particular, the cartridge is designed such that the aerosol with the particles to be enlarged can be passed through the cartridge. All features, properties, and advantages of the above-mentioned method and the above-mentioned device also apply to the cartridge, and vice versa. A cartridge can be filled with molten or liquid sulfone and / or with powdered sulfone.

[0082] A further aspect of the invention is the use of a cartridge containing a solid sulfone for enlarging particles of an aerosol and / or in a device for enlarging particles of an aerosol. The above-mentioned embodiments, features, advantages, and effects of the method, use, and device also apply to the cartridge, and vice versa.

[0083] List of reference symbols:

[0084] Particle 1

[0085] Aerosol 2

[0086] Supersaturated vapor 3

[0087] Non-supersaturated steam 4

[0088] Enlarged particle 5

[0089] Aerosol source 10

[0090] Soot generator 11

[0091] Drying 12

[0092] Excess air 13

[0093] Size selection 14

[0094] Flow control 15

[0095] Particle filter 16 Mass flow controller 17

[0096] Opening 18

[0097] Reference measuring instrument 19

[0098] Condensation particle counter 20

[0099] Condensation particle counter 21

[0100] Mixing chamber 22

[0101] Low pressure area 23

[0102] Humidifier 24

[0103] Entrance 25

[0104] Outlet 26

[0105] Saturator 27

[0106] Condenser 28

[0107] Optics 29

[0108] Storage container 30

[0109] Condensation particle counter 31

[0110] DMSO 32

[0111] Butanol 33

[0112] Water 34

[0113] Operating resources 35

[0114] Humidifier 36

[0115] Supersaturation ratio OR

[0116] Mobility diameter d

[0117] Counting efficiency (d particle counter) ECPC

[0118] Vapor pressure p

[0119] Diameter x

[0120] Cartridge 40

[0121] Flow path 41

[0122] Heating device 42

[0123] Solid Sulfone 43

[0124] Outlet interface 45

[0125] Inflow interface 46

[0126] Entrance opening 48

[0127] Exit opening 49

[0128] Pipe 50

[0129] Wall 51

Claims

Claims 1. A method for enlarging particles (1) of an aerosol (2), in which the particles (1) come into contact with a supersaturated vapor (3), a sulfoxide or a sulfone being used to produce the supersaturated vapor (3).

2. Process according to claim 1, characterized in that the supersaturated vapor (3) is produced from dimethyl sulfoxide or from dimethyl sulfone.

3. Method according to one of the preceding claims, characterized in that the particles (1) have a diameter of less than 50 nm, preferably less than 10 nm.

4. Method according to one of the preceding claims, characterized in that the supersaturated steam (3) is produced by cooling non-supersaturated steam (4), wherein the non-supersaturated steam (4) is produced at a temperature above 30°C, preferably above 60°C, in particular wherein the non-supersaturated steam (3) is produced at a temperature above 80°C, in particular above 110°C.

5. Method according to one of the preceding claims, characterized in that the supersaturated steam (3) is produced by cooling non-supersaturated steam (3) to a temperature above 10°C and / or below 30°C.

6. Method according to one of the preceding claims, characterized in that a mixture of the sulfoxide or sulfone with water is used to produce the supersaturated steam (3).

7. Method according to one of the preceding claims, characterized in that the enlargement of the particles (1) takes place under negative pressure, wherein the negative pressure is in particular between 150 hPa and 750 hPa.

8. Method according to one of the preceding claims, characterized in that the enlarged particles (1) are optically detected and a number of particles (1) is determined.

9. Method according to one of the preceding claims, characterized in that the aerosol (2) contains lipophilic and / or insoluble particles (1).

10. Method according to one of the preceding claims, characterized in that the enlargement of the particles (1) takes place at a height of more than 500 m above the earth's surface.

11. Use of a sulfoxide or a sulfone for producing a supersaturated vapor (3), wherein the supersaturated vapor (3) comes into contact with the particles (1) in order to enlarge particles (1) of an aerosol (2).

12. Device for enlarging particles (1) of an aerosol (2), comprising a condenser (28) for enlarging particles (1) of an aerosol (2) by means of a supersaturated vapor (3), wherein a reservoir (30) for a sulfoxide or sulfone is present in order to produce the supersaturated vapor (3).

13. Device according to the preceding claim, characterized in that the device comprises a mixing device for producing a mixture of a sulfoxide and water.

14. Device according to one of the two preceding claims, characterized in that the storage container (30) is designed as a particularly replaceable cartridge (40) which contains a solid sulfone, wherein the cartridge (40) is designed in particular such that the aerosol (2) with the particles (1) to be enlarged can be guided through the cartridge (40).

15. Cartridge (40) with a solid sulfone for enlarging particles (1) of an aerosol (2), wherein the cartridge (40) is designed in particular such that the aerosol (2) with the particles (1) to be enlarged can be guided through the cartridge (40).

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