A method for preparing preactivated ice nuclei

Abstract

The invention discloses a method for preparing pre-activated ice nuclei, which comprises the following steps: step A, placing an aerosol sample in a condenser for cleaning oil stains; step B, setting the initial temperature in the condenser to below 0°C, gradually reducing the temperature of the condenser, activating the aerosol sample therein at each temperature level, and evacuating the condenser after each activation; step C, gradually increasing the temperature of the condenser to the initial temperature, activating the aerosol sample in the condenser again at each temperature level, and reducing the relative humidity after each activation to sublime ice crystals; step D, screening and preserving ice nucleus samples with an increased number of ice crystals after two rounds of activation, i.e., ice nuclei that have been effectively pre-activated, according to the concentration of ice crystals formed in the condenser at the same temperature in step B and step C; the invention further improves the effectiveness of making pre-activated ice crystals, and the prepared pre-activated ice nuclei can be used as catalysts for artificial weather modification.

Description

Technical Field

[0001] The invention belongs to the field of atmospheric science and technology, and particularly relates to a method for preparing pre-activated ice nuclei. Background Art

[0002] In mixed-phase clouds, precipitation is mainly caused by the growth and fall of ice crystals. However, the formation of ice crystals in clouds usually requires the presence of ice nuclei. The so-called ice nuclei refer to aerosol particles that can form ice crystals on their surface. The concentration of ice nuclei in nature is usually very small, so a large amount of liquid water in the cloud cannot be effectively converted into ice crystals to form precipitation. The principle of artificial rain and snow enhancement is to sow appropriate artificial ice nuclei in the cloud so that more ice crystals can be produced in the cloud. These ice crystal particles grow and fall through methods such as the Bergeron process, thereby increasing precipitation.

[0003] Preactivated ice nuclei refer to natural ice nuclei that have been activated once (i.e. ice crystals have formed on their surface). Even if they are placed in relatively dry air to allow the ice crystals on their surface to sublimate or melt, they can be activated again at a relatively higher temperature. Therefore, preactivated ice nuclei are a catalyst that can be used in artificial rain and snow enhancement, artificial hail prevention, and artificial improvement of air quality. At present, the commonly used artificial ice nuclei are silver iodide particles, but silver iodide is mainly effective when the temperature is below -10°C, and cannot effectively convert a large amount of liquid water in the cloud area above -10°C into ice crystals. Summary of the invention

[0004] The present invention provides a method for preparing preactivated ice nuclei, which can further improve the effectiveness of ice nucleus activation. The prepared preactivated ice nuclei can be used as catalysts for artificial rain and snow enhancement, artificial hail prevention, and artificial improvement of air quality, thereby providing technical support for improving artificial weather modification.

[0005] In order to solve the above problems, the present invention adopts the following technical solutions:

[0006] In one aspect, the present invention provides a method for preparing preactivated ice nuclei, the method comprising the following steps:

[0007] Step A, placing the aerosol sample into a condenser, and cleaning the aerosol sample from oil stains;

[0008] Step B, setting the temperature in the condenser to temperature T1, wherein the condenser temperature T1 is set to be below 0°C, setting the ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface to h1, wherein h1 is greater than 1, and filling the condenser with water vapor to form ice crystals on the aerosol sample; evacuating the condenser to make all the ice crystals sublime; gradually reducing the temperature of the condenser and repeating the above step B, when the temperature in the condenser is reduced to temperature T n When the retention temperature T n Ice crystals formed in the lower condenser;

[0009] Step C, the temperature in the condenser is increased from temperature T n Raised to temperature T n-1 ; Set the ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface as h2, where h2 is less than 1, connect the condenser to the water vapor source to allow all ice crystals in the condenser to sublime; set the ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface as h3, where h3 is greater than 1, fill the condenser with water vapor, and form ice crystals on the aerosol sample; gradually increase the temperature of the condenser to temperature T1 and repeat the above step C;

[0010] Step D, screening and preserving effectively pre-activated ice nuclei according to the concentration of ice crystals formed in the condenser at the same temperature in step B and step C.

[0011] Furthermore, the method for cleaning the aerosol sample from oil pollution includes:

[0012] The temperature in the condenser was set to -10°C, and water vapor with a relative humidity of 116% on the ice surface was prepared. The water vapor was input into the condenser to form ice crystals on the aerosol sample. The condenser was evacuated to allow all ice crystals to sublime, completing the cleaning of the ice core sample.

[0013] Further, according to the concentration of ice crystals formed in the condenser at the same temperature in step B and step C, the method for screening and preserving the effectively preactivated ice nuclei includes:

[0014] Compare the concentrations of ice crystals formed in the condenser at the same temperature in step B and step C; when the concentration of ice crystals formed in step C is greater than the concentration of ice crystals formed in step B, save the aerosol sample; when the concentration of ice crystals formed in step C is less than or equal to the concentration of ice crystals formed in step B, discard the aerosol sample.

[0015] Furthermore, the temperature range of the condenser is -10°C to -20°C.

[0016] Furthermore, the temperature of the condenser is between T1 and T n The values ​​are -10℃, -14℃, -17℃ and -20℃ respectively.

[0017] Furthermore, the ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface is set to h1=108%.

[0018] Furthermore, the ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface is set to h2=60%.

[0019] Furthermore, the ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface is set to h3=104%.

[0020] Furthermore, the relative ice surface humidity in the condenser is calculated as follows:

[0021]

[0022]

[0023] In the formula, RH is the relative ice surface humidity in the condenser, e is the water vapor pressure of the water vapor source, is the saturated water vapor pressure on the condenser sample relative to the ice surface, and T is the temperature inside the condenser.

[0024] On the other hand, the present invention also provides an application system of the pre-activated ice nucleus preparation method, including a condenser and a refrigeration device for adjusting the temperature of the condenser; one end of the condenser is connected to the vacuum pump pipeline; the other end of the condenser is connected to the water vapor source pipeline; valves are provided on the pipelines between the condenser and the vacuum pump and between the condenser and the water vapor source.

[0025] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0026] The present invention first cleans the aerosol sample from oil stains, and then uses a temperature- and humidity-controllable condenser and a two-round cycle step-by-step cooling method to activate the ice nuclei. In the first round of cooling and activation, the temperature in the condenser is adjusted to gradually decrease from -10°C to -20°C, water vapor is input into the condenser, the ice nuclei are combined with the water vapor to form ice crystals, the condenser is evacuated, and the ice crystals sublime.

[0027] During the second round of cooling and activation, the temperature in the condenser is adjusted from -17°C to -10°C, water vapor is input into the condenser, and the ice crystal concentration obtained in the first round of cooling and activation is compared with the ice crystal concentration obtained in the second round of cooling and activation. If the number concentration of ice crystals generated in the second round of activation at the same temperature is greater than the number concentration of ice crystals in the first round of activation, the pre-activation effect of ice nuclei under the temperature and humidity conditions is verified, and pre-activated ice nuclei are obtained, which further improves the effectiveness of making pre-activated ice crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a simplified schematic diagram of an instrument provided by an embodiment of the present invention;

[0029] Figure 2 is a flow chart of a method for preparing preactivated ice nuclei provided in an embodiment of the present invention;

[0030] Figure 3 It is a schematic diagram of ice crystals obtained when the temperature of the first round of step-by-step cooling activation condenser is -10°C provided by an embodiment of the present invention;

[0031] Figure 4 It is a schematic diagram of ice crystals obtained when the temperature of the first round of step-by-step cooling activation condenser is -14°C provided by an embodiment of the present invention;

[0032] Figure 5 It is a schematic diagram of ice crystals obtained when the temperature of the first round of step-by-step cooling activation condenser is -17°C provided by an embodiment of the present invention;

[0033] Figure 6 It is a schematic diagram of ice crystals obtained when the temperature of the first round of step-by-step cooling activation condenser is -20°C provided by an embodiment of the present invention;

[0034] Figure 7 It is a schematic diagram of ice crystals obtained when the temperature of the second round of step-by-step cooling activation condenser provided by an embodiment of the present invention is -17°C;

[0035] Figure 8 It is a schematic diagram of ice crystals obtained when the temperature of the second round of step-by-step cooling activation condenser provided by an embodiment of the present invention is -14°C;

[0036] Fig. 9 It is a schematic diagram of ice crystals obtained when the temperature of the second round of step-by-step cooling activation condenser provided by an embodiment of the present invention is -10°C;

[0037] Fig.10 is a schematic diagram of ice crystal number concentration results obtained after two rounds of step-by-step cooling of ice crystals provided by an embodiment of the present invention; DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the protection scope of the present invention.

[0039] Example 1

[0040] like Figure 2 As shown, an embodiment of the present invention provides a method for preparing preactivated ice nuclei, and batches of preactivated ice nuclei are prepared. The method comprises the following steps:

[0041] Step A, firstly, the aerosol sample is placed in the condenser, and the condenser is tightly sealed to create a completely closed space to prevent the external environment from interfering with the cooling process, and the condenser is evacuated using a vacuum pump; in this near-vacuum environment, the memory effect of the ice nucleus is completely destroyed, so that the ice nucleus is not affected by the memory effect during the first activation process;

[0042] The temperature in the condenser is set to -10°C, water vapor with an initial relative humidity of 116% of the ice surface is prepared, and water vapor is input into the condenser; wherein the relative humidity in the condenser is calculated based on the water vapor pressure, and the saturated water vapor pressure relative to the water surface and the ice surface is obtained by the following formula:

[0043]

[0044]

[0045] In the formula, is the saturated vapor pressure on the water surface;

[0046] During the ice nucleus activation process, the relative ice surface humidity in the condenser can be obtained by the following formula:

[0047]

[0048] Where RH is the relative ice surface humidity in the condenser, e is the water vapor pressure of the water vapor source, is the saturated water vapor pressure on the condenser sample relative to the ice surface, and T is the temperature inside the condenser.

[0049] The condenser is evacuated to complete the cleaning of the aerosol sample. This step is to remove the oil stains that may be attached to the sample sheet to prevent the oil stains from affecting the preparation results and interfering with the reading of ice crystals;

[0050] Step B, such as Figures 3 to 6 As shown in FIG. 1 , the first round of step-by-step cooling and activation process of the ice nucleus includes: setting the temperature in the condenser to -10°C, preparing water vapor with a relative humidity of 108% on the ice surface at this temperature; inputting water vapor into the condenser, combining the water vapor with the ice nucleus to form ice crystals, and observing the formation of ice crystals in the condenser, as shown in FIG. Figure 3 As shown, ice crystals have been generated in the condenser, data is recorded, water vapor is stopped from being transported, and the condenser is returned to a closed state; a vacuum pump is used to evacuate the condenser, at which time all ice crystals sublimate and the memory effect of the ice nucleus is destroyed;

[0051] The temperature in the condenser is set to -14°C, and water vapor with a relative humidity of 108% on the ice surface is prepared at this temperature; water vapor is input into the condenser, the formation of ice crystals in the condenser is observed, data is recorded, and the condenser is sealed; the condenser is evacuated to a vacuum, at which time all the ice crystals sublimate, and the memory effect of the ice nucleus is destroyed again.

[0052] The temperature of the condenser is adjusted to -17°C, and water vapor with a relative ice surface humidity of 108% is prepared at this temperature; water vapor is input into the condenser, and the formation of ice crystals in the condenser is observed, and the condenser is evacuated to a vacuum, at which time all the ice crystals sublime, and the memory effect of the ice nucleus is destroyed again.

[0053] The condenser temperature is adjusted to -20°C, and water vapor with a relative humidity of 108% on the ice surface is prepared at this temperature; the water vapor is input into the condenser, and the formation of ice crystals in the condenser is observed, thereby completing the first round of step-by-step cooling and activation process; Figures 3 to 5 As shown, the amount of ice crystals in the condenser in step B continues to increase.

[0054] Step C, such as Figures 7 to 9 As shown, the second round of step-by-step cooling and activation process for the ice nucleus includes: adjusting the temperature of the condenser to -17°C, setting the ratio of the water vapor pressure in the water vapor source and the saturated water vapor pressure in the condenser relative to the ice surface to 60%, connecting the water vapor source and the condenser, and because there are ice crystals in the condenser and the water vapor retained in step B, the water vapor pressure in the condenser is greater than the set water vapor pressure, and the water vapor in the condenser will diffuse out, so that the water vapor concentration in the condenser is reduced, and the ice crystals in the condenser sublime; after the ice crystals are completely sublimated, re-preparing water vapor with a relative humidity of 104% of the ice surface in the condenser at this temperature, the temperature in the condenser is -17°C, and the water vapor is input into the condenser, and the water vapor combines with the ice nuclei to form ice crystals, and the formation of ice crystals in the condenser is observed.

[0055] The temperature in the condenser is adjusted to -14°C, the water vapor pressure in the water vapor source is set to 60% of the saturated water vapor pressure in the condenser relative to the ice surface, and the water vapor source and the condenser are connected; since there are ice crystals and water vapor retained in the previous step in the condenser, the water vapor pressure in the condenser is greater than the set water vapor pressure, and the water vapor in the condenser will diffuse out, so that the water vapor concentration in the condenser is reduced, and the ice crystals sublime; after the ice crystals are completely sublimated, water vapor with a relative humidity of 104% of the ice surface in the condenser at this temperature is re-prepared, and the water vapor is input into the condenser, and the water vapor combines with ice nuclei to form ice crystals, and the formation of ice crystals in the condenser is observed and recorded;

[0056] The temperature of the condenser is adjusted to -10°C, the water vapor pressure in the water vapor source is set to 60% of the saturated water vapor pressure in the condenser relative to the ice surface, and the water vapor source and the condenser are connected; so that the water vapor pressure in the condenser is greater than the set water vapor pressure, the water vapor in the condenser will diffuse out, so that the water vapor concentration in the condenser is reduced, and the ice crystals sublime. After the ice crystals are completely sublimated, water vapor with a relative humidity of 104% of the ice surface is re-prepared, and the water vapor is selected in the condenser, and the water vapor combines with the ice nucleus to form ice crystals; the formation of ice crystals in the condenser is observed.

[0057] Step D, based on the concentration of ice crystals formed in the condenser at the same temperature in step B and step C, the method for screening and preserving ice nuclei that have been effectively preactivated comprises:

[0058] Compare the concentrations of ice crystals formed in the condenser at the same temperature in step B and step C; when the concentration of ice crystals formed in step C is greater than the concentration of ice crystals formed in step B, save the aerosol sample; when the concentration of ice crystals formed in step C is less than or equal to the concentration of ice crystals formed in step B, discard the aerosol sample.

[0059] like Fig.10 As shown, the number concentration of ice crystals generated by the ice nuclei in the second round of activation is greater than the number concentration of ice crystals in the first round of activation, which verifies the pre-activation effect of the ice nuclei under the temperature and humidity conditions, and at the same time obtains pre-activated ice nuclei. This method can be applied to prepare pre-activated ice nuclei and spread them into clouds as catalysts to enhance the generation of ice crystals at a temperature of -10°C in the clouds. The prepared pre-activated ice nuclei can be used as catalysts for artificial rain and snow enhancement, artificial hail prevention, and artificial improvement of air quality, thereby providing technical support for improving artificial weather modification.

[0060] Example 2

[0061] like Figure 1 As shown, this embodiment also provides an application system for the pre-activated ice nucleus preparation method, and the system is applied to the pre-activated ice nucleus preparation method described in Example 1, and the application system includes a condenser and a refrigeration device for adjusting the temperature of the condenser; one end of the condenser is connected to the vacuum pump pipeline; the other end of the condenser is connected to the water vapor source pipeline; valves are provided on the pipelines between the condenser and the vacuum pump and between the condenser and the water vapor source.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing preactivated ice nuclei, characterized in that: The method comprises the following steps: Step A, placing the aerosol sample into a condenser, and cleaning the aerosol sample from oil stains; Step B, set the temperature in the condenser to , the condenser temperature Set the temperature to below 0℃, set the ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface to h1, where h1 is greater than 1, and fill the condenser with water vapor to form ice crystals on the aerosol sample; evacuate the condenser to make all the ice crystals sublime; gradually reduce the temperature of the condenser and repeat the above step B. When the temperature in the condenser drops to Keep the temperature Ice crystals formed in the lower condenser; Step C, the temperature in the condenser is Raise to temperature ; Set the ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface to h2, where h2 is less than 1, connect the condenser to the water vapor source to allow all ice crystals in the condenser to sublime; set the ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface to h3, where h3 is greater than 1, fill the condenser with water vapor, and form ice crystals on the aerosol sample; gradually increase the temperature of the condenser to temperature Repeat step C above; Step D, based on the concentration of ice crystals formed in the condenser at the same temperature in step B and step C, the method for screening and preserving ice nuclei that have been effectively preactivated comprises: Compare the concentration of ice crystals formed in the condenser at the same temperature in step B and step C; When the concentration of ice crystals formed in step C is greater than the concentration of ice crystals formed in step B, the aerosol sample is saved; when the concentration of ice crystals formed in step C is less than or equal to the concentration of ice crystals formed in step B, the aerosol sample is discarded.

2. A method for preparing preactivated ice nuclei according to claim 1, characterized in that: Methods for cleaning aerosol samples from oil contamination include: The temperature in the condenser was set to -10°C, and water vapor with a relative humidity of 116% on the ice surface was prepared. The water vapor was input into the condenser to form ice crystals on the aerosol sample. The condenser was evacuated to allow all ice crystals to sublime, completing the cleaning of the ice core sample.

3. The method for preparing preactivated ice nuclei according to claim 1, characterized in that: The temperature range of the condenser is -10°C to -20°C.

4. A method for preparing preactivated ice nuclei according to claim 3, characterized in that: The temperature of the condenser To temperature The values ​​are -10℃, -14℃, -17℃ and -20℃ respectively.

5. The method for preparing preactivated ice nuclei according to claim 1, characterized in that: The ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface is set to h1=108%.

6. The method for preparing preactivated ice nuclei according to claim 1, characterized in that: The ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface is set to h2=60%.

7. The method for preparing preactivated ice nuclei according to claim 1, characterized in that: The ratio of the water vapor pressure in the water vapor source to the saturated water vapor pressure in the condenser relative to the ice surface is set to h3=104%.

8. A method for preparing preactivated ice nuclei according to any one of claims 5 to 7, characterized in that: The relative ice surface humidity calculation formula in the condenser is: ； ； In the formula, is the relative ice surface humidity in the condenser, is the water vapor pressure of the water vapor source, is the saturated water vapor pressure on the condenser sample relative to the ice surface, and T is the temperature inside the condenser.

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