Methods, uses, devices and cartridges for enlarging aerosol particles

Abstract

The present invention relates to a method and apparatus for enlarging particles of an aerosol, and to the use of an agent for generating supersaturated vapor. In the method for enlarging particles (1) of an aerosol (2), the particles (1) are contacted with supersaturated vapor (3). The supersaturated vapor (3) is generated using a sulfoxide or sulfone, such as dimethyl sulfoxide or dimethyl sulfone. These substances are non-flammable, non-hazardous to health, and non-hazardous to the environment, making them easy to handle. They do not cause odor pollution or damage to the climate. The same particle counting efficiency is achieved as with butanol, which is traditionally used as an agent.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for enlarging aerosol particles, the use of an operating agent to generate supersaturated vapor, and a cartridge. [Background technology]

[0002] Aerosol particles in the (low) nanometer range cannot be easily detected optically. To detect such particles optically, they must first be enlarged. In this process, the particles grow, for example, by about two orders of magnitude, so that optical detection becomes possible. This may be, for example, in the 300 nm range. Enlargement may be performed by condensation growth. This process is also known as activation. The particles act as condensation nuclei in an atmosphere of supersaturated vapor of the agent. Vapor molecules attach to the particles diffusively. Particles enlarged or grown in this way can be detected using optical methods.

[0003] An aerosol is a mixture of solid and / or liquid particles in a gas. The gas is called a carrier gas. For the purposes of this application, the term gas includes gas mixtures. The particles of an aerosol are also called aerosol particles.

[0004] Technically, particles are enlarged, for example, in a condensation particle counter (CPC). The agent is brought to a constant temperature in liquid form. This is done in a saturator through which a stream of carrier gas flows. Depending on the temperature, a saturated vapor pressure, which is the partial pressure of the agent, is established in the carrier gas stream. The saturated carrier gas stream is fed into a condenser, which is colder than the saturator. Due to the lower temperature, the partial pressure of the agent is now supersaturated. As soon as the particles come into contact with this gas stream, they act as condensation nuclei, grow, and accumulate the agent. Optical detectors are used to detect the particles. For example, the gas stream can be illuminated with a focused light source, for example a laser. For example, radiation scattered by the particles can be detected. In this way, individual particles and / or the number and / or concentration of particles can be detected.

[0005] Alcohols, such as butanol, ethanol, or isopropanol, are typically used as agents for generating supersaturated vapor. However, alcohols are flammable or highly flammable, have a strong odor, and are harmful or toxic. Therefore, comprehensive safety measures are required when handling and using them. Furthermore, these substances have low flash points and / or boiling points, which limit the maximum temperature of the saturator and therefore the maximum achievable supersaturation. This leads to a limit on the lower detection limit, as the supersaturation level determines the critical diameter of particles that can still be activated.

[0006] Diethylene glycol (DEG) can also be used as an agent in special cases. Diethylene glycol can activate very small aerosol particles less than 2 nm at saturator temperatures of 50-60°C. However, particles activated with diethylene glycol only grow to about 100 nm, requiring further activation in a downstream CPC. Furthermore, diethylene glycol is hazardous to health.

[0007] It is also possible to use fluorinated hydrocarbons such as perfluorotributylamine, PFTBA, available under the trademark 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 and also poses health and climate hazards.

[0008] The above features, advantages and definitions may be combined individually or in combination with the subject matter claimed and described. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to improve the particle size distribution of aerosols, in particular for the optical determination of aerosol properties. Preferably, the aforementioned disadvantages of the prior art are at least partially eliminated. The object is achieved by a method according to claim 1, as well as by a use, a device and a cartridge according to the further claims. Advantageous embodiments are set out in the dependent claims. [Means for solving the problem]

[0010] A method for enlarging particles of an aerosol, in which the particles are contacted with a supersaturated vapor, helps to solve the problem. A sulfoxide or sulfone is used to generate the supersaturated vapor.

[0011] Many sulfoxides and sulfones are not labeled with H phrases (hazard statements) or P phrases (precautionary statements) of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). The substances are easy to handle, as they are not flammable, harmful to health, or dangerous to the environment. There is no odor pollution or damage to the climate. Overall, this significantly reduces the required technical effort and simplifies particle removal. There are no restrictions on use in sensitive areas. The method can therefore also be used in passenger transport, transportation, aerospace, automotive sectors, medicine, clean rooms and laboratories, research, chemistry, biology and the environment.

[0012] Sulfoxides and sulfones have similar physicochemical properties to butanol, which has often been used for particle enlargement, particularly with regard to vapor pressure, diffusion properties, and operating temperature range. Therefore, this group of substances is suitable to function as a supersaturated vapor for particle entrapment. They are a substitute for the standard agent, 1-butanol, with significantly better properties. A further advantage consists in the fact that conventional devices, such as condensation particle counters or their components, can be used, unmodified or with only minor modifications, to carry out the method according to the invention.

[0013] In accordance with the present invention, a sulfoxide or sulfone is used to generate supersaturated vapor. This substance is also referred to below as the agent according to the present invention. Furthermore, other substances and / or mixtures of substances may be used to generate supersaturated vapor. In one configuration, the supersaturated vapor is generated from a sulfoxide or sulfone. The supersaturated vapor comprises or consists of a gaseous sulfoxide or sulfone.

[0014] Supersaturated steam contains more gas particles than would be the case in thermodynamic equilibrium. Supersaturated steam is therefore denser than steam in thermodynamic equilibrium between steam and condensate. The vapor pressure is higher than the saturated vapor pressure. When condensation nuclei are added, condensation can occur in the supersaturated steam, which can eventually bring about thermodynamic equilibrium.

[0015] The particles are contacted with the supersaturated vapor. Specifically, non-supersaturated vapor is generated and converted to supersaturated vapor by cooling. The non-supersaturated vapor can be saturated or non-saturated vapor. The particles or aerosol may already be present in the non-supersaturated vapor and may be cooled along with it. The cooling process can convert the non-supersaturated vapor containing the particles into supersaturated vapor containing the particles. Therefore, it is not necessary to introduce the particles into already supersaturated vapor.

[0016] Sulfoxides have an organically bound sulfur and have the general structure R 1 -S(=O)-R 2 is a class of chemical compounds having R 1 and R 2 is an organic residue. Sulfones have organically bonded sulfur and oxygen and have the general structural formula R 1 -S(=O)2-R 2 is a class of compounds having R 1 and R 2 is an organic residue.

[0017] The choice of organic residue, also known as the ligand, can affect the melting point and / or boiling point of each material, which in turn affects the vapor pressure. Therefore, it is easy to determine and use a material suitable for a particular requirement. Mixtures of sulfoxides, sulfones, or at least one sulfoxide and at least one sulfone can be used.

[0018] In one configuration, the method is carried out in a particle counter, preferably a CPC, especially an ultrafine aerosol condensation nuclei / particle counter.

[0019] In one embodiment, the supersaturated vapor is generated from dimethyl sulfoxide. In dimethyl sulfoxide (DMSO), each of the two organic residues is a methyl group. Laboratory tests and field studies have shown that particle enlargement using this substance produces particularly good results. The counting efficiency of optical particle counters is comparable to that of particle counters operated with conventional butanol. The same is true for activation sizes, especially the minimum (critical) activation size. DMSO is inexpensive and readily available, and its low vapor pressure results in only a small amount of agent consumption compared to, for example, butanol (approximately 10% of butanol consumption).

[0020] In one embodiment, the supersaturated vapor is generated from dimethyl sulfone, where each of the two organic residues is a methyl group. Due to the enlarged particles, this material provides particularly good results. The counting efficiency of optical particle counters is comparable to that of conventional butanol-based particle counters.

[0021] For both sulfones and sulfoxides, organic residues such as ethyl or cyclic (cyclo) compounds can be used. Symmetrical or unsymmetrical 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, particularly less than 10 nm, preferably less than 5 nm or less than 3 nm. The particles have this diameter before contact with the supersaturated vapor. In particular, the average diameter of a plurality of particles is intended. For example, this is d 50 Starting from this diameter, growth or thickening occurs.

[0023] It has been shown that even very small particles can be enlarged using the agents according to the invention, and in particular these particles can be optically detected after enlargement.

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

[0025] The agent according to the present invention has a higher flash point and a higher boiling point compared to previously used substances such as 1-butanol. Therefore, higher temperatures can be used according to the present invention. For example, butanol has a flash point of 35°C, so from a practical standpoint, higher temperatures are not possible with this agent.

[0026] Higher temperatures allow for higher supersaturation and therefore larger and faster growth. Finally, particularly low detection limits in terms of particle size (activatable particle size) can be achieved at temperatures typical of the saturator.

[0027] The maximum temperature for DMSO may be 150°C, since thermal decomposition occurs above this temperature. If other substances are used, the maximum temperature may be higher, for example, for dimethyl sulfone, it may be higher than 230°C. The maximum temperature can be set within a wide range by selecting a suitable organic residue. In one embodiment, non-supersaturated vapor is generated at temperatures above 80°C, in particular above 110°C. In this way, particularly low detection limits can be achieved, even down to nanoparticles of less than 5 nm or even less than 2 nm, especially without an additional activation step. This may be done particularly at a condenser temperature of 5°C to 10°C.

[0028] In one embodiment, the supersaturated steam is produced by cooling non-supersaturated steam to a temperature below 20° C., in particular below 10° C. In particular, the temperature is above 0° C. or above 5° C. This target temperature can be set using particularly simple technical means.

[0029] In one embodiment, supersaturated steam is generated by cooling non-supersaturated steam to a temperature above room temperature and / or 15°C, in particular below 20°C and / or 30°C, in particular 25°C. In many applications, this target temperature can be set without any technical means, or at least without cooling. Thus, cooling, for example by a Peltier element, can be omitted. If necessary, a heating device can be provided to increase the temperature if required. Heating is technically much less complex than cooling. With the agent according to the invention, a saturator temperature as low as in conventional devices is no longer necessary. A higher saturator temperature allows sufficient supersaturation to be achieved at a higher condenser temperature.

[0030] In one embodiment, a mixture of sulfoxide or sulfone and water is used to generate supersaturated vapor. In particular, the sulfoxide or sulfone used to generate supersaturated vapor is diluted with water. The use of water alone as an agent is not possible due to its diffusion properties. However, a mixture of the agent and water according to the present invention has been shown to result in effective particle enlargement. At the same time, various mixing ratios make it possible to adapt the melting point of each sulfoxide or sulfone to the respective operating conditions or requirements.

[0031] The melting point of DMSO can be lowered from 18°C ​​to, for example, 5°C to 15°C by adding a small amount of water. For example, temperatures between 5°C and 15°C are common in airplane cockpits where particle counters can be operated to investigate atmospheric aerosols. When diluted with water, particle counters can be operated under these conditions without additional technical effort, for example, down to -10°C when diluted with 10% water by volume. In this case, there is no need to worry about the agent solidifying or freezing in the reservoir or piping.

[0032] In particular, supersaturated steam is produced from sulfoxides or sulfones diluted with water. Typically, water is used as the diluent.

[0033] In one embodiment, the volume fraction of water in the mixture is less than 10%. It has been shown that water contents up to 10% of the total volume of the mixture do not significantly impair the counting efficiency of particle counters. In other words, reliable results can be obtained up to this water content. In one configuration, the water content is less than 5%. This achieves particularly accurate results. Water does not affect particle enlargement.

[0034] In one embodiment, the particles are enlarged under negative pressure. In particular, the negative pressure is between 150 hPa and 750 hPa. Typically, the generation of non-supersaturated vapor and / or optical determination is also performed under negative pressure. The pressures mentioned are absolute pressures.

[0035] In one embodiment, the expanded particles are optically detected. In one embodiment, the number of particles is determined. In one configuration, at least one property of the aerosol is optically determined after the particles of the aerosol are expanded. The optical determination may be, for example, the detection of the number of particles in a specific volume and / or a specific time interval. The optical determination may also be the optical detection of one or more particle properties. For example, the size of the particle and / or the average size of a plurality of particles may be determined. Size typically refers to the diameter. Preferably, the number concentration of the particles may be determined.

[0036] After the particles have been enlarged, a gas volume or gas stream containing the enlarged particles is typically present. In one configuration, the gas volume or gas stream is illuminated with light, particularly by a focused light source such as a laser. In one configuration, an optical detector is provided to detect the enlarged particles. In one configuration, the detector is configured to detect scattered radiation. In particular, evaluation electronics are provided to determine the number, concentration, or number concentration of the particles from the signal received from the detector. For example, the evaluation electronics are configured, for example, to count the number of particles in a specific time interval. In one configuration, the evaluation electronics have access to information regarding the volumetric flow rate or volume of the gas.

[0037] In one embodiment, the aerosol is selected from ambient air, combustion exhaust gases, production exhaust gases, clean room supply air, clean room exhaust air, substantially enclosed space supply air, and substantially enclosed space exhaust air. The clean room may be, for example, a clean room in the chemical industry, pharmaceutical industry, chip production, hospital, or laboratory, such as an S0, S1, S2, S3, or S4 laboratory. The clean room supply air may be analyzed for monitoring purposes. The clean room exhaust air may be a separately exhausted air stream for detection (room air monitoring) or an exhaust air stream for ventilating an independently existing clean room. The clean room exhaust air may be analyzed for monitoring the condition and / or contamination of the clean room. The production exhaust gas may originate, for example, from industrial, medical, medical technology, pharmaceutical, chemical, or military applications. In particular, the method or use can be used for determining dust and / or aerosol loads, process optimization, combustion residue analysis, quality monitoring, climate relevance studies, particle load studies, hazard avoidance, risk assessment, and / or production control. Ambient air refers in particular to air from a specific region of the Earth's atmosphere. In the case of combustion exhaust gases, this may be exhaust gas from a combustion engine, such as a diesel or gasoline engine. The method or use may be performed during engine development, combustion optimization, and / or technical monitoring of an engine or vehicle. The space may be the internal combustion engine of a car, aircraft, ship, or rail vehicle. In particular, particle numbers, such as particle number per volume, particle number per time, or particle number concentrations corresponding to particle number per time and power, or values ​​derived therefrom, can be used.

[0038] The substantially enclosed space may be a passenger compartment, for example the cabin of an airplane, where the quality of the supply and / or exhaust air may be measured to determine and / or adjust the quality of the cabin air.

[0039] In one embodiment, the aerosol comprises lipophilic and / or insoluble particles. The insoluble particles may comprise, for example, silicates and / or mineral dust. Lipophilic particles, like hydrophilic particles, may be enlarged by an agent according to the present invention. Lipophilic particles may be hydrophobic. In one configuration, the aerosol comprises hydrophilic particles. Hydrophilic particles may be lipophobic. In one configuration, the aerosol comprises lipophilic and hydrophilic particles. In one configuration, the aerosol comprises organic particles. Any combination is possible. In one configuration, substantially all of the particles of the aerosol are lipophilic and / or hydrophilic.

[0040] In one embodiment, the particles are enlarged at altitudes greater than 500 m above the Earth's surface and / or from an aircraft.

[0041] Preferably, the altitude is higher than 1,000 m, in one embodiment higher than 5,000 m and / or lower than 20,000 m above the ground, and in one embodiment lower than 15,000 m above the ground. Additionally or alternatively, the enlargement is carried out in or on an airplane. In particular, particles are also counted at the aforementioned altitudes. In this way, aerosols present at different heights in the atmosphere can be investigated. Due to current safety regulations, the use of butanol on passenger aircraft is no longer practically permitted. However, the agent according to the present invention still makes this possible.

[0042] A further aspect of the present invention is the use of a sulfoxide or sulfone to generate supersaturated vapor, which is brought into contact with particles of an aerosol in order to enlarge the particles. In particular, the number of enlarged particles is detected by a particle counter. All the features, advantages and effects of the method described at the beginning apply mutatis mutandis to the use, and vice versa.

[0043] A further aspect of the present invention is an apparatus, in particular a part of a condensation particle counter or a condensation particle counter. The apparatus comprises a condenser for enlarging particles of an aerosol with supersaturated vapor. A reservoir of sulfoxide or sulfone is provided for generating supersaturated vapor. In particular, the reservoir comprises sulfoxide or sulfone. In particular, the condensation particle counter further comprises a saturator for generating non-supersaturated vapor. All features, advantages, and effects of the method described at the beginning apply mutatis mutandis to the apparatus, and vice versa.

[0044] In particular, the apparatus or condensation particle counter does not include a cooling device for cooling the condenser. Because the higher saturator temperature of the agent according to the present invention allows for sufficient supersaturation even at slightly higher condenser temperatures, cooling, e.g., electrical cooling, can be omitted to simplify the apparatus. This is reinforced by the fact that at low temperatures, the effect of temperature differences on the partial pressure of the agent is smaller than at high temperatures. This means that cooling elements, fans, associated controls, and hot-side heat sinks are not required. Overall, therefore, the installation space of the apparatus can be significantly reduced.

[0045] In one configuration, the device is part of a condensation particle counter for analyzing combustion exhaust gases, in particular for technical monitoring of vehicles such as automobiles, aircraft, ships and / or rail vehicles. 50 The device may be a condensation particle counter according to the European Committee for Standardization CEN.

[0046] In the following, exemplary embodiments of the present invention are described in further detail with reference to the figures. The features of the exemplary embodiments may be used individually or in multiple combinations with the claimed subject matter, unless otherwise indicated. The scope of protection claimed is not limited to the exemplary embodiments.

[0047] The diagram shows: [Brief explanation of the drawings]

[0048] [Figure 1]FIG. 1 shows the experimental setup. [Figure 2] FIG. 10 is a diagram showing a counting efficiency curve. [Figure 3] Kelvin-Kohler diagram. [Figure 4] FIG. 2 is a diagram showing a vapor pressure curve. [Figure 5] FIG. 1 shows a schematic setup of a condensation particle counter. [Figure 6] FIG. 10 is a diagram showing the schematic structure of another condensation particle counter. [Figure 7] 1 shows a cartridge according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0049] Figure 1 shows a test setup for investigating a condensation particle counter 21 with generated aerosol 2 for testing purposes to evaluate different agents. Aerosol 2 containing particles 1 is generated in an aerosol source 10, e.g., a nebulizer, and is first fed to a size fractionator 14 via drying 12 and adjusting for excess air 13. Preferably, a differential mobility analyzer (DMA) is used, which only allows particles of a specific size to pass, thus generating a monodisperse aerosol.

[0050] Furthermore, soot particles produced by the soot generator 11 may be directed to a size fractionator 14. The aerosol is fed via an opening 18 and a line into a mixing chamber 22, which is part of a low pressure region 23. This line is connected to a flow control 15 via a particle filter 16 and a mass flow controller 17. There is also a humidifier 24, which influences the humidity in the mixing chamber 22. A device for diluting and / or pressure controlling the atmosphere in the mixing chamber 22 is located above the humidifier 24. Both devices are connected to the mixing chamber 22 by the mass flow controller 17 and the particle filter 16, respectively. There is also a temperature control for the mixing chamber 22.

[0051] Several measurement devices are connected to the mixing chamber 22 via outlet lines: a reference measuring instrument 19 for determining the number concentration, e.g., a Faraday cup electrometer, a condensation particle counter 20 using a conventional agent such as 1-butanol, and a condensation particle counter 21 using an agent according to the invention.

[0052] Soot particles are hydrophobic and lipophilic and insoluble in water. Particles produced by nebulizers are particularly hydrophilic and lipophobic. By using both devices, different aerosols, and possibly mixtures, can be investigated.

[0053] Figure 2 shows a diagram containing curves of counting efficiency for different agents. Specifically, the data shown was recorded using the device shown in Figure 1. The counting efficiency E of the particle counter CPC is plotted against the particle diameter d in nanometers. Diameter d is the mobility diameter measured using DMA. The individual curves refer to a condensation particle counter B-CPC operated conventionally with butanol and an identical D-CPC operated with the agent DMSO according to the invention. The counting efficiency was normalized to the measurement of a reference measuring instrument 19 (see FIG. 1). Measurements were carried out with each of the CPCs under different negative pressures: 200 hPa, 500 hPa, and 700 hPa.

[0054] At each pressure level, the counting efficiency E CPC It can be seen that there is no difference in d 50 The cut-off point, also known as the counting point, is shown to be 5.5 nm for both CPCs, regardless of the pressure used. Therefore, changes to the agent according to the invention shown here using DMSO as an example do not affect counting efficiency.

[0055] Figure 3 shows the Kelvin-Kohler diagrams for the agents DMSO, butanol, and water, plotting the supersaturation ratio, OR, versus the droplet diameter, x, of each agent in μm. NaCl particles with a diameter of 13 nm at 20 °C were considered. The supersaturation ratio, OR, corresponds to the saturation quotient and is calculated as the quotient of the saturated vapor pressure on the curved surface of the particle and the saturated vapor pressure on the flat surface. The maximum values ​​of the curves define the critical radius and critical supersaturation. As soon as this point is exceeded, i.e., to the right of each maximum in the diagram, the particle is activated and continues to grow stably in a non-equilibrium state. In this way, growth over several orders of magnitude can occur.

[0056] When the saturation quotient is greater than 1, supersaturation exists. The saturation quotient must be above the respective curve for particles to grow; below it, the deposited agent will evaporate. It can be seen that when using DMSO32, 1.2% supersaturation is required, while with butanol33, only 0.7% supersaturation is required. It is also possible to produce 1.2% supersaturation without any problems using commercially available CPC.

[0057] FIG. 4 shows the vapor pressure curves for the agents DMSO 32, butanol 33, and water 34. The vapor pressure p in bar is plotted on a logarithmic axis over temperature in °C. Because the vapor pressure of DMSO 32 is an order of magnitude lower than that of butanol 33, the loss of agent, and therefore consumption, is significantly reduced for DMSO 32. This reduction can be confirmed experimentally. It is similar for other agents according to the present invention. Furthermore, because the curves for butanol 33 and DMSO 32 run in parallel, the supersaturation is similar for the same temperature difference between the saturator and the condenser. Therefore, DMSO 32 behaves similarly to butanol 33 as an agent.

[0058] 5 shows a condensation particle counter 31 for carrying out the device and / or method according to the invention. An inlet 25 for supplying an aerosol 2 containing particles 1 is followed by a saturator 27 for generating non-supersaturated vapor 4. A humidifier 36 is located within the saturator, which is designed, for example, as a sponge or a similar component with a large surface area. The humidifier may be arranged on one or more walls within the saturator 27. To generate non-supersaturated vapor 4, a reservoir 30 containing an agent 35, i.e., a sulfoxide or sulfone, is connected to the humidifier 36. For this purpose, the agent 35 is evaporated in the humidifier 36 at a first temperature, which is typically below the boiling temperature of the agent 35 used.

[0059] The gas stream is then cooled to produce supersaturated vapor 3. This is done in a condenser 28 to enlarge the particles 1 of the aerosol 2. The supersaturated vapor 3 comes into contact with the particles 1 of the aerosol 2, which then grow.

[0060] An optical element 29 is arranged between the condenser 28 and the outlet and is used to detect particles, which can be counted using evaluation electronics connected to the optical element 28. In particular, the device includes evaluation electronics.

[0061] Particle growth is shown diagrammatically: in the saturator 27, particles 1 grow in size only slowly to the equilibrium radius, whereas in the condenser 28, particles grow rapidly over several orders of magnitude with increasing residence time in a non-equilibrium (activated) state, resulting in the formation of enlarged particles 5 with increased diameter.

[0062] Figure 6 shows an apparatus according to the invention and / or a condensation particle counter 31 for carrying out a method according to the invention. To avoid repetition, only the differences from the apparatus of Figure 5 will be described. The apparatus comprises a replaceable cartridge 40 containing solid sulfone 43. The cartridge 40 may be mechanically connected to other parts of the apparatus. Connection points for this purpose are shown diagrammatically as gaps. The apparatus may also have a heating device 42 for directly or indirectly heating the cartridge 40 and / or the solid sulfone 43 contained therein. The cartridge 40 functions in particular as a saturator 27.

[0063] In one configuration, the device includes one or more flow paths 41 for the aerosol 2. The flow paths 41 of the device can include an outlet interface 45 for transferring the aerosol 2 to the cartridge 40 and / or an inlet interface 46 for transferring the aerosol 2 from the cartridge 40. In one configuration, the cartridge 40 includes an inlet port 48 for introducing the aerosol 2 received from the outlet interface 45 into the cartridge 40. In one configuration, the cartridge 40 includes an outlet port 49 for expelling the aerosol 2 from the cartridge 40 to the inlet interface 46 of the device.

[0064] The condenser 28 and / or the optical elements 29 may be designed similarly to Figure 5. Particle growth is also shown here schematically.

[0065] FIG. 7 shows a cross section of a cartridge 40 according to the present invention. The cartridge 40 includes a tube 50 having an outer wall 51. The wall 51 may be made of metal. The solid sulfone 43 is disposed inside the outer wall, for example, as a continuous and / or circumferential layer having an essentially constant thickness. As shown, the layer thickness may be smaller than the wall thickness, or may be the same or thicker. The layer thickness may vary in different parts of the tube 50, particularly along the longitudinal extension of the tube 50. Thus, a different layer thickness may exist in the inlet region of the tube than in the outlet region of the tube. Because the solid sulfone 43 has a relatively low thermal conductivity, a thicker layer requires more energy for heating. Therefore, the layer thickness may be selected to achieve an optimum between energy efficiency and the lifespan of the cartridge 40, depending on the requirements. The layer thickness is also a measure of the fill level of the cartridge 40 with solid sulfone and / or the remaining capacity of the cartridge 40. The layer thickness, and therefore the capacity of the cartridge 40, can be determined indirectly via the heating and / or the energy required for this. The circular cross section shown in Figure 7 is advantageous because such a cartridge can be attached to and used with existing particle counters without modification.

[0066] In one embodiment, solid sulfones are used, which make them particularly easy to handle.

[0067] In one embodiment, the apparatus includes a mixing device for producing a mixture of sulfoxide and water. The mixing device may be such that predetermined amounts of sulfoxide and water are mixed in a stream that is fed directly to an evaporation device for producing supersaturated vapor. The mixing may be continuous for at least a period of time. The mixing device may be such that there is a mixing vessel to which predetermined amounts of sulfoxide and water are added. In this manner, the mixture may be produced in batches. The mixing device may be automatic and / or controlled by a controller. In this manner, a suitable mixture can be produced in an automated manner.

[0068] In an alternative or complementary embodiment, the reservoir is configured to receive a mixture of sulfoxide and water.

[0069] When supersaturated vapor is generated from sulfoxides or sulfones diluted with water, the water can act as an antifreeze.

[0070] In one embodiment, the volume fraction of water in the mixture is less than 60%, for example, about 46%. In one embodiment, the volume fraction of water in the mixture is less than 40 mol%, for example, about 30 mol%. The melting point of pure dimethyl sulfoxide (DMSO) is 18°C. For example, a mixture of dimethyl sulfoxide and water containing 30 mol% DMSO, which corresponds to about 43% by volume, can reduce the melting point to about -140°C. In this way, the present invention can be used at very low temperatures. This is advantageous, for example, for measurements on or in an airplane or in Antarctica. This opens up further fields of application.

[0071] In one embodiment, the reservoir is designed as a cartridge containing, for example, a solid sulfone. The sulfone may be, for example, dimethyl sulfone. The cartridges are particularly interchangeable. This means that a used or empty cartridge can be removed from the device to be replaced with a new or filled cartridge. The cartridge may be permanently installed or may exist as a separate, mechanically removable module. In the latter case, the cartridge may be located upstream of the device and / or upstream of the particle counter.

[0072] Thus, the cartridge may be replaceable, similar to a printer cartridge. In particular, the cartridge and / or device is designed so that an aerosol containing particles to be enlarged can be directed through the cartridge. In one configuration, the cartridge and / or the sulfone disposed within the cartridge includes a through opening through which the aerosol flow can be directed. The through opening serves as a flow path for the aerosol, thereby bringing the aerosol into contact with the sublimated sulfone.

[0073] In one configuration, the cartridge may be heated. In particular, the cartridge includes an outer wall, preferably made of a material with good thermal conductivity, such as metal, e.g., copper. The sulfone may be disposed inside the outer wall. The outer wall is particularly designed so that a heat source positioned outside the outer wall can heat the sulfone through the wall. In particular, the device includes a heat source configured to heat the cartridge located within the device. In particular, the heat source is positioned outside the outer wall of the cartridge and is configured so that the heat source can heat the outer wall so that the sulfone can be heated through the outer wall. Alternatively or additionally, the cartridge may include a heat source, which may be designed as described.

[0074] In one configuration, the cartridge may be heated differently in different portions, particularly relative to the longitudinal extension of the cartridge or tube. For example, different temperatures may be achieved in different portions. The different portions of the cartridge or tube may be made of separate components and / or may be thermally insulated from one another. The heating device may be configured to achieve different temperatures in different portions of the cartridge.

[0075] 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 up to 150° C., in particular up to 130° C., preferably up to 90° C., particularly preferably up to 70° C. In other words, the cartridge and / or device is configured to allow such heating.

[0076] Solid sulfones have been shown to partially sublimate at temperatures of, for example, at least 35°C or 40°C, thereby coarsening aerosol particles through condensation. Such solid sulfones have been shown to be easy to handle and very economical. No storage bottles, hoses, or porous materials are required for vaporization. Such solid sulfones can be used in existing condensation particle counters. Furthermore, solid sulfones can be used within the temperature range of existing condensation particle counters. Using solid sulfones in direct contact with the aerosol is particularly advantageous and simple. Cartridges containing the solid sulfones may be easily replaceable, achieving reproducible results.

[0077] In principle, the cartridge may have any shape. In one configuration, the cartridge includes or is designed to include a tubular section. The tubular section may be straight. In that case, the tubular outer wall of the cartridge may include sulfone. The sulfone is located, in particular, as an inner layer of the cartridge and / or on the inner side of the outer wall. The layer preferably has a thickness of less than 3 cm, in particular less than 1 cm, and in one configuration less than 0.5 cm or less than 0.2 cm. The layer thickness is in particular greater than 1 μm. A central passage opening can be formed along the longitudinal axis of the tube as a flow path for the aerosol. This configuration is particularly simple and inexpensive to manufacture.

[0078] In one configuration, the cartridge is curved or spiraled, for example, the tubular portion of the cartridge is bent or spiraled, thus providing a longer path with a smaller cartridge volume.

[0079] A further aspect of the present invention is a cartridge containing solid sulfone for use in an apparatus for enlarging particles of an aerosol and / or for enlarging particles of an aerosol. The apparatus may be an apparatus according to the present invention. The sulfone may be, for example, dimethyl sulfone. In particular, the cartridge is designed so that the aerosol containing the particles to be enlarged can pass through the cartridge. All features, properties and advantages of the methods and apparatus described above also apply to the cartridge, and vice versa. The cartridge can be filled with molten and / or liquid sulfone and / or powdered sulfone.

[0080] A further aspect of the present invention is the use of a cartridge comprising 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. [Explanation of symbols]

[0081] 1 particle 2. Aerosols 3. Supersaturated steam 4 Non-supersaturated steam 5. Enlarged particles 10 Aerosol Sources 11 Soot Generator 12 Drying 13 Excess air 14 Size sorter 15 Flow Control 16 Particle Filter 17 Mass flow controller 18 Opening 19 Reference measuring equipment 20 Condensation Particle Counter 21 Condensation particle counter 22 Mixing chamber 23 Low pressure area 24 Humidifier 25 Entrance 26 Exit 27 Saturator 28 Condenser 29 Optical Elements 30 reservoir 31 Condensation Particle Counter 32 DMSO 33 Butanol 34 water 35 Agents 36 Humidifier OR supersaturation ratio d mobility diameter E CPC Counting efficiency (particle counter) p vapor pressure x diameter 40 cartridges 41 Flow path 42 Heating Devices 43 Solid sulfone 45 Outflow Interface 46 Inflow Interface 48 Inlet Port 49 Exit Port 50 tubes 51 Wall

Claims

1. A method for enlarging particles (1) of an aerosol (2), comprising: The particles (1) come into contact with the supersaturated vapor (3), The method wherein a sulfoxide or sulfone is used to generate supersaturated vapor (3).

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

3. 3. The method according to claim 1 or 2, characterized in that the particles (1) have a diameter of less than 50 nm, preferably less than 10 nm.

4. Supersaturated steam (3) is produced by cooling non-supersaturated steam (4), 4. The method according to claim 1, wherein the non-supersaturated steam (4) is generated at a temperature above 30°C, preferably above 60°C, in particular the non-supersaturated steam (3) is generated at a temperature above 80°C, in particular above 110°C.

5. 5. The method according to claim 1, wherein the supersaturated steam (3) is generated by cooling the non-supersaturated steam (3) to a temperature higher than 10°C and / or lower than 30°C.

6. 6. The method according to claim 1, wherein a mixture of sulfoxide or sulfone with water is used to generate the supersaturated vapor (3).

7. 7. The method according to claim 1, wherein the enlargement of the particles (1) is carried out under negative pressure, said negative pressure being in particular between 150 hPa and 750 hPa.

8. 8. The method according to claim 1, wherein the enlarged particles (1) are optically detected and the number of particles (1) is determined.

9. 9. The method according to any one of claims 1 to 8, characterized in that the aerosol (2) comprises lipophilic and / or insoluble particles (1).

10. 10. The method according to any one of claims 1 to 9, characterized in that the enlargement of the particles (1) is carried out at an altitude higher than 500 m above the earth's surface.

11. Use of a sulfoxide or sulfone to generate supersaturated vapor (3), A use in which supersaturated vapor (3) is brought into contact with particles (1) of an aerosol (2) to enlarge the particles (1).

12. A device for enlarging particles (1) of an aerosol (2), comprising: a condenser (28) for enlarging the particles (1) of the aerosol (2) with supersaturated steam (3); The apparatus is provided with a reservoir (30) of sulfoxide or sulfone to generate supersaturated vapor (3).

13. 13. The apparatus according to claim 12, characterized in that it comprises a mixing device for producing a mixture of sulfoxide and water.

14. the reservoir (30) is designed as a cartridge (40), in particular as a replaceable cartridge (40) containing a solid sulfone, 14. Device according to claim 12 or 13, characterized in that the cartridge (40) is designed in particular so that the aerosol (2) containing the particles (1) to be enlarged can be led through the cartridge (40).

15. A cartridge (40) containing a solid sulfone for enlarging particles (1) of an aerosol (2), A cartridge (40) which is particularly designed so that an aerosol (2) containing particles (1) to be enlarged can be guided through the cartridge (40).

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