Method for detecting boron and phosphorus impurities in photovoltaic polycrystalline silicon recovery hydrogen
By combining absorption in series with silver nitrate solution and mass spectrometry, the problem of accurate detection of boron and phosphorus impurities in hydrogen recovered from polycrystalline silicon for photovoltaic applications was solved, thus improving the quality of recovered hydrogen.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU ZHONGNENG POLYSILICON TECH DEV
- Filing Date
- 2026-04-03
- Publication Date
- 2026-05-12
AI Technical Summary
Current technology lacks a method to accurately detect the boron and phosphorus impurity content in hydrogen recovered from polycrystalline silicon used in photovoltaics.
A series of double-hole capped absorption bottles were used to absorb and recover boron and phosphorus impurities in hydrogen gas using silver nitrate solution. The boron and phosphorus impurities in the recovered hydrogen gas were then detected by inductively coupled plasma mass spectrometry and calculated.
It enables accurate detection of boron and phosphorus impurities in recovered hydrogen, ensuring the quality of recovered hydrogen and reducing production costs.
Smart Images
Figure CN122016993A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for detecting boron and phosphorus impurities in hydrogen recovered from polycrystalline silicon used in photovoltaics, belonging to the field of hydrogen detection technology in polycrystalline silicon recovery. Background Technology
[0002] The reduction tail gas of polysilicon for photovoltaic applications is mainly hydrogen, containing small amounts of impurities such as chlorosilanes, nitrogen, hydrogen chloride, and metallic and non-metallic elements. After impurity removal and drying, the recovered hydrogen can be reused for reduction, thereby reducing production costs. The quality of the recovered hydrogen is a crucial factor affecting the quality of polysilicon. Impurities such as boron and phosphorus mainly exist in the form of chlorides, diborane, and phosphine. Accurate detection of their content is of paramount importance for the recycling and reuse of hydrogen. Currently, there is a lack of methods for accurately detecting the boron and phosphorus content in the recovered hydrogen. Summary of the Invention
[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for detecting boron and phosphorus impurities in hydrogen recovered from photovoltaic polycrystalline silicon, which can accurately detect the boron and phosphorus content in the recovered hydrogen.
[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:
[0005] A method for detecting boron and phosphorus impurities in hydrogen recovered from polycrystalline silicon used in photovoltaics includes the following steps:
[0006] Step a: Clean the four double-hole capped absorption bottles with ultrapure water and then dry them with nitrogen. Use two of the absorption bottles as sample absorption bottles and the remaining two as blank absorption bottles. Finally, add silver nitrate solution to each absorption bottle.
[0007] Step b: Connect the two sample absorption bottles in series and install them on the sampler. Then, pass the recovered hydrogen gas through the silver nitrate solution so that the silver nitrate solution can absorb the boron and phosphorus impurities in the recovered hydrogen gas. At the same time, seal the two sample absorption bottles and do not connect them to the sampler.
[0008] Step c: After absorption is complete, weigh the two sample absorption bottles together with the solutions inside, then mix the solutions in the two sample absorption bottles together and use inductively coupled plasma mass spectrometry to detect the boron and phosphorus impurity elements in the sample absorption liquid.
[0009] Step d: The solutions in the two blank absorption bottles are mixed together and detected by inductively coupled plasma mass spectrometry to obtain the content of boron and phosphorus impurity elements in the blank solution;
[0010] Step e: Calculate the content of boron and phosphorus impurities in the recovered hydrogen gas based on the weight of the sample absorption bottle, the weight of the sample absorption bottle together with the internal solution, the boron and phosphorus impurity content in the sample absorption liquid, and the boron and phosphorus impurity content in the blank solution.
[0011] In step a, the concentration of the silver nitrate solution is 0.04~0.06 g / L.
[0012] In step a, the absorption bottle is made of PFA.
[0013] In step a, the volume of silver nitrate solution in each absorption bottle is the same, which is 40~60mL.
[0014] In step b, the inlet flow rate of the recovered hydrogen gas into the sample absorption bottle is 0.4~0.6 L / min, and the inlet time is 100~140 min.
[0015] The boron and phosphorus impurity content in the sample absorption solution in step c and the boron and phosphorus impurity content in the blank solution in step d should be measured at least twice until the relative deviation between the two parallel measurements is no more than 15%, and the average value should be taken.
[0016] In step e, the formula for calculating the content of boron and phosphorus impurities in the recovered hydrogen is:
[0017] ;
[0018] Where M represents the content of boron or phosphorus impurities in the recovered hydrogen. This indicates the content of boron or phosphorus impurities in the absorbent. This indicates the content of boron or phosphorus impurities in the blank solution of the blank sample vial. This indicates the weight of the sample absorption bottle along with the solution inside. Indicates the weight of the sample absorption bottle. This indicates the volume of recovered hydrogen gas introduced under standard conditions. This indicates the density of hydrogen gas.
[0019] Under standard conditions, the volume of recovered hydrogen gas introduced is... The calculation formula is:
[0020] ;
[0021] in, This represents the atmospheric pressure value during absorption. Indicates standard temperature. Indicates the intake airflow. Indicates the intake time. Indicates standard pressure. This indicates the temperature at which absorption occurs.
[0022] The beneficial effects of this invention are as follows: This invention provides a method for detecting boron and phosphorus impurities in recovered hydrogen gas from photovoltaic polycrystalline silicon. Two sample absorption bottles are connected in series and installed on a sampler. Then, recovered hydrogen gas is introduced and passed through a silver nitrate solution. The silver nitrate solution absorbs the boron and phosphorus impurities in the recovered hydrogen gas. Silver nitrate can form stable complexes with boron and phosphorus elements in the recovered hydrogen gas. Furthermore, the absorption is complete due to the connection of two sample absorption bottles in series, thus achieving accurate detection of the boron and phosphorus content in the recovered hydrogen gas. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the absorption device in the method for detecting boron and phosphorus impurities in hydrogen recovered from photovoltaic polycrystalline silicon according to the present invention. Detailed Implementation
[0024] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.
[0025] Example 1
[0026] This invention discloses a method for detecting boron and phosphorus impurities in hydrogen recovered from photovoltaic polycrystalline silicon, comprising the following steps:
[0027] Step 1: Clean the four double-hole capped absorption bottles with ultrapure water and then dry them with nitrogen. The absorption bottles are made of PFA. In this invention, the double holes on the absorption bottles are normally sealed, but connected to the outside when an external pipeline is inserted. Two of the absorption bottles are weighed and designated as sample absorption bottles. The total weight was 303.8g (the sum of the two samples). The remaining two absorption bottles were used as blank absorption bottles, with a total weight of 307.1g. Finally, silver nitrate solution was added to each absorption bottle (including the two sample absorption bottles and the two blank absorption bottles). The volume of silver nitrate solution in each absorption bottle was the same, 50mL. The concentration of the silver nitrate solution was 0.05g / L, and the preparation method was as follows: Weigh 0.5g of silver nitrate standard reagent, dilute to 500mL with ultrapure water, then transfer 5mL of the above solution and dilute to 100mL with ultrapure water to prepare the absorption solution.
[0028] Step two: Connect the two sample absorption bottles in series and install them onto the sampler. Then, introduce recovered hydrogen gas, allowing it to pass through a silver nitrate solution, which absorbs boron and phosphorus impurities from the recovered hydrogen. The inlet flow rate of the recovered hydrogen gas into the sample absorption bottle is 0.5 L / min, and the inlet time is 120 min. Figure 1As shown, the entire absorption device includes sample sampling bottles A and B connected in series. A hydrogen recovery line is connected to sample sampling bottle A, and a float flowmeter is installed on the hydrogen recovery line. Sample sampling bottle B is connected to the absorption tail gas line. The recovered hydrogen passes sequentially through the hydrogen recovery line, sample sampling bottle A, sample sampling bottle B, and the absorption tail gas line. The inlet lines in sample sampling bottles A and B must be inserted 0.5 cm above the bottom of the absorption bottle, and the outlet lines must be inserted at the outlet at the top of the absorption bottle. The connections between the lines and the absorption bottles must be airtight. A blank absorption bottle is brought to the site but not connected to the sampler. After sampling, it is brought back to the laboratory for testing. Simultaneously, atmospheric pressure... For 100.7 kPa and temperature The temperature is 28℃.
[0029] Step 3: After absorption is complete, weigh both sample absorption bottles together with their internal solutions, recording the weight as 342.3g. Then, mix the solutions from both sample absorption bottles together and analyze the boron and phosphorus impurity content in the sample absorption solution using inductively coupled plasma mass spectrometry. The boron and phosphorus impurity content in the sample absorption solution should be measured at least twice, until the relative deviation between the two parallel measurements is no greater than 15%, and the average value should be taken.
[0030] Step four: Weigh the two blank absorption bottles together with their internal solutions, recording the weight as 406.8g. Mix the solutions from the two blank absorption bottles and analyze the boron and phosphorus impurity content in the blank solution using inductively coupled plasma mass spectrometry. The boron and phosphorus impurity content in the blank solution is measured at least twice, until the relative deviation between the two parallel measurements is no greater than 15%, and the average value is taken. This invention, by treating the absorbent in the sample absorption bottle and the absorbent in the blank absorption bottle under the same conditions for the same duration, effectively eliminates the influence of boron (B) and phosphorus (P) impurities released from the absorption bottle and absorbed by the absorbent, thus making the calculation results of the boron and phosphorus impurity content in the final recovered hydrogen more accurate.
[0031] Step 5: Calculate the boron and phosphorus impurity content in the recovered hydrogen gas based on the weight of the sample absorption bottle, the weight of the sample absorption bottle together with the internal solution, the boron and phosphorus impurity content in the sample absorption solution, and the boron and phosphorus impurity content in the blank solution.
[0032] The formula for calculating the content of boron and phosphorus impurities in recovered hydrogen is as follows:
[0033] ;
[0034] Where M represents the content of boron or phosphorus impurities in the recovered hydrogen, in ng / g. This indicates the content of boron or phosphorus impurities in the sample absorption solution, in ng / g. This indicates the content of boron or phosphorus impurities in the blank solution, in ng / g. This indicates the weight of the sample absorption bottle along with the internal solution, in grams. This indicates the weight of the sample absorption bottle, in grams. This indicates the volume of recovered hydrogen gas introduced under standard conditions, in liters (L). This indicates the density of hydrogen gas, which is 0.0899 g / L.
[0035] Under standard conditions, the volume of recovered hydrogen gas introduced is... The calculation formula is:
[0036] ;
[0037] in, This represents the atmospheric pressure during absorption, in kPa. This indicates the standard temperature, which is 273.1 K. Indicates intake airflow, unit: L / min. Indicates intake time, unit: min. This represents the standard pressure, which is 101.3 kPa. This indicates the temperature at which absorption occurs, in °C.
[0038] The calculation results of this embodiment are shown in Table 1. The content of boron impurity element in the recovered hydrogen is 0.71 ng / g, and the content of phosphorus impurity element in the recovered hydrogen is 0.95 ng / g.
[0039] Table 1. Content of boron and phosphorus impurities in the recovered hydrogen in Example 1
[0040]
[0041] Example 2
[0042] This invention discloses a method for detecting boron and phosphorus impurities in hydrogen recovered from photovoltaic polycrystalline silicon, comprising the following steps:
[0043] Step 1: Clean four double-hole capped absorption bottles with ultrapure water and then dry them with nitrogen. The absorption bottles are made of PFA. In this invention, the double holes on the absorption bottles are normally sealed, but connected to the outside when an external pipeline is inserted. Weigh two of the absorption bottles to be used as sample absorption bottles. The remaining two, without weighing, are used as blank absorption bottles. Finally, add silver nitrate solution to each absorption bottle (including two sample absorption bottles and two blank absorption bottles). The volume of silver nitrate solution in each absorption bottle is the same, 40 mL. The concentration of the silver nitrate solution is 0.06 g / L. The preparation method is as follows: Weigh 0.6 g of silver nitrate standard reagent, dilute to 500 mL with ultrapure water, then transfer 5 mL of the above solution and dilute to 100 mL with ultrapure water to prepare the absorption solution.
[0044] Step two: Connect the two sample absorption bottles in series and install them onto the sampler. Then, introduce recovered hydrogen gas, allowing it to pass through a silver nitrate solution, which absorbs boron and phosphorus impurities from the recovered hydrogen. The inlet flow rate of the recovered hydrogen gas into the sample absorption bottle is 0.6 L / min, and the inlet time is 100 min. Figure 1 As shown, the entire absorption device includes sample sampling bottles A and B connected in series. A hydrogen recovery line is connected to sample sampling bottle A, and a float flow meter is installed on the hydrogen recovery line. Sample sampling bottle B is connected to the absorption tail gas line. The recovered hydrogen passes sequentially through the hydrogen recovery line, sample sampling bottle A, sample sampling bottle B, and the absorption tail gas line. The inlet lines in sample sampling bottles A and B must be inserted 0.5 cm above the bottom of the absorption bottle, and the outlet lines must be inserted at the outlet at the top of the absorption bottle. The connections between the lines and the absorption bottles must be airtight. A blank absorption bottle should be brought to the site without connecting it to the sampler. After sampling, it should be brought back to the laboratory for testing.
[0045] Step 3: After absorption is complete, weigh both sample absorption bottles together with their internal solutions. Then, mix the solutions from both bottles together and use inductively coupled plasma mass spectrometry (ICP-MS) to determine the boron and phosphorus impurity content in the sample absorption solution. The boron and phosphorus impurity content in the sample absorption solution should be measured at least twice, until the relative deviation between the two parallel measurements is no greater than 15%, and the average value should be taken.
[0046] Step four: Mix the solutions from the two blank absorption bottles together and analyze them using inductively coupled plasma mass spectrometry to obtain the boron and phosphorus impurity element content in the blank solution. The boron and phosphorus impurity element content in the blank solution should be measured at least twice, until the relative deviation between the two parallel measurements is no greater than 15%, and the average value is taken.
[0047] Step 5: Calculate the boron and phosphorus impurity content in the recovered hydrogen gas based on the weight of the sample absorption bottle, the weight of the sample absorption bottle together with the internal solution, the boron and phosphorus impurity content in the sample absorption solution, and the boron and phosphorus impurity content in the blank solution.
[0048] The formula for calculating the content of boron and phosphorus impurities in recovered hydrogen is as follows:
[0049] ;
[0050] Where M represents the content of boron or phosphorus impurities in the recovered hydrogen, in ng / g. This indicates the content of boron or phosphorus impurities in the sample absorption solution, in ng / g. This indicates the content of boron or phosphorus impurities in the blank solution, in ng / g. This indicates the weight of the sample absorption bottle along with the internal solution, in grams. This indicates the weight of the sample absorption bottle, in grams. This indicates the volume of recovered hydrogen gas introduced under standard conditions, in liters (L). This indicates the density of hydrogen gas, which is 0.0899 g / L.
[0051] Under standard conditions, the volume of recovered hydrogen gas introduced is... The calculation formula is:
[0052] ;
[0053] in, This represents the atmospheric pressure during absorption, in kPa. This indicates the standard temperature, which is 273.1 K. Indicates intake airflow, unit: L / min. Indicates intake time, unit: min. This represents the standard pressure, which is 101.3 kPa. This indicates the temperature at which absorption occurs, in °C.
[0054] Example 3
[0055] This invention discloses a method for detecting boron and phosphorus impurities in hydrogen recovered from photovoltaic polycrystalline silicon, comprising the following steps:
[0056] Step 1: Clean four double-hole capped absorption bottles with ultrapure water and then dry them with nitrogen. The absorption bottles are made of PFA. In this invention, the double holes on the absorption bottles are normally sealed, but connected to the outside when an external pipeline is inserted. Weigh two of the absorption bottles to be used as sample absorption bottles. The remaining two, without weighing, are used as blank absorption bottles. Finally, add silver nitrate solution to each absorption bottle (including two sample absorption bottles and two blank absorption bottles). The volume of silver nitrate solution in each absorption bottle is the same, 60 mL. The concentration of the silver nitrate solution is 0.04 g / L. The preparation method is as follows: Weigh 0.4 g of silver nitrate standard reagent, dilute to 500 mL with ultrapure water, then transfer 5 mL of the above solution and dilute to 100 mL with ultrapure water to prepare the absorption solution.
[0057] Step two: Connect the two sample absorption bottles in series and install them onto the sampler. Then, introduce recovered hydrogen gas, allowing it to pass through a silver nitrate solution, which absorbs boron and phosphorus impurities from the recovered hydrogen. The inlet flow rate of the recovered hydrogen gas into the sample absorption bottle is 0.4 L / min, and the inlet time is 140 min. Figure 1As shown, the entire absorption device includes sample sampling bottles A and B connected in series. A hydrogen recovery line is connected to sample sampling bottle A, and a float flow meter is installed on the hydrogen recovery line. Sample sampling bottle B is connected to the absorption tail gas line. The recovered hydrogen passes sequentially through the hydrogen recovery line, sample sampling bottle A, sample sampling bottle B, and the absorption tail gas line. The inlet lines in sample sampling bottles A and B must be inserted 0.5 cm above the bottom of the absorption bottle, and the outlet lines must be inserted at the outlet at the top of the absorption bottle. The connections between the lines and the absorption bottles must be airtight. A blank absorption bottle should be brought to the site without connecting it to the sampler. After sampling, it should be brought back to the laboratory for testing.
[0058] Step 3: After absorption is complete, weigh both sample absorption bottles together with their internal solutions, recording the weight as 342.3g. Then, mix the solutions from both sample absorption bottles together and analyze the boron and phosphorus impurity content in the sample absorption solution using inductively coupled plasma mass spectrometry. The boron and phosphorus impurity content in the sample absorption solution should be measured at least twice, until the relative deviation between the two parallel measurements is no greater than 15%, and the average value should be taken.
[0059] Step four: Mix the solutions from the two blank absorption bottles together and analyze them using inductively coupled plasma mass spectrometry to obtain the boron and phosphorus impurity element content in the blank solution. The boron and phosphorus impurity element content in the blank solution should be measured at least twice, until the relative deviation between the two parallel measurements is no greater than 15%, and the average value is taken.
[0060] Step 5: Calculate the boron and phosphorus impurity content in the recovered hydrogen gas based on the weight of the sample absorption bottle, the weight of the sample absorption bottle together with the internal solution, the boron and phosphorus impurity content in the sample absorption solution, and the boron and phosphorus impurity content in the blank solution.
[0061] The formula for calculating the content of boron and phosphorus impurities in recovered hydrogen is as follows:
[0062] ;
[0063] Where M represents the content of boron or phosphorus impurities in the recovered hydrogen, in ng / g. This indicates the content of boron or phosphorus impurities in the sample absorption solution, in ng / g. This indicates the content of boron or phosphorus impurities in the blank solution, in ng / g. This indicates the weight of the sample absorption bottle along with the internal solution, in grams. This indicates the weight of the sample absorption bottle, in grams. This indicates the volume of recovered hydrogen gas introduced under standard conditions, in liters (L). This indicates the density of hydrogen gas, which is 0.0899 g / L.
[0064] Under standard conditions, the volume of recovered hydrogen gas introduced is... The calculation formula is:
[0065] ;
[0066] in, This represents the atmospheric pressure during absorption, in kPa. This indicates the standard temperature, which is 273.1 K. Indicates intake airflow, unit: L / min. Indicates intake time, unit: min. This represents the standard pressure, which is 101.3 kPa. This indicates the temperature at which absorption occurs, in °C.
[0067] Comparative Example
[0068] This embodiment is the same as Embodiment 1, except that the silver nitrate solution in this embodiment is replaced with ultrapure water, and the weight of the sample absorption bottle in step one is... The weight is 305.5g. In step two, the atmospheric pressure is recorded. For 101.2 kPa and temperature The temperature was 27℃. In step three, the two sample absorption bottles, along with their internal solutions, were weighed together and recorded as 345.8g. The calculation results of this comparative example are shown in Table 2. The content of boron impurity element in the recovered hydrogen was 0.08 ng / g, and the content of phosphorus impurity element in the recovered hydrogen was 0.16 ng / g.
[0069] Table 2. Content of boron and phosphorus impurities in recovered hydrogen in the comparative examples.
[0070]
[0071] Comparing Example 1 with the comparative example, it can be seen that the impurity content in the recovered hydrogen calculated by the detection method of the present invention is much higher than that of the detection method in the comparative example. This proves that the present invention uses silver nitrate solution to absorb boron and phosphorus impurities in the recovered hydrogen. Silver nitrate forms stable complexes with boron and phosphorus elements in the recovered hydrogen. The method of the present invention can accurately detect the boron and phosphorus content in the recovered hydrogen.
[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for detecting boron and phosphorus impurities in hydrogen recovered from photovoltaic polycrystalline silicon, characterized in that: Includes the following steps: Step a: Clean the four double-hole capped absorption bottles with ultrapure water and then dry them with nitrogen. Use two of the absorption bottles as sample absorption bottles and the remaining two as blank absorption bottles. Finally, add silver nitrate solution to each absorption bottle. Step b: Connect the two sample absorption bottles in series and install them on the sampler. Then, pass the recovered hydrogen gas through the silver nitrate solution so that the silver nitrate solution can absorb the boron and phosphorus impurities in the recovered hydrogen gas. At the same time, seal the two sample absorption bottles and do not connect them to the sampler. Step c: After absorption is complete, weigh the two sample absorption bottles together with the solutions inside, then mix the solutions in the two sample absorption bottles together and use inductively coupled plasma mass spectrometry to detect the boron and phosphorus impurity elements in the sample absorption liquid. Step d: Mix the solutions from the two blank absorption bottles together and use inductively coupled plasma mass spectrometry to detect the boron and phosphorus impurity elements in the blank solution; Step e: Calculate the content of boron and phosphorus impurities in the recovered hydrogen gas based on the weight of the sample absorption bottle, the weight of the sample absorption bottle together with the internal solution, the boron and phosphorus impurity content in the sample absorption liquid, and the boron and phosphorus impurity content in the blank solution.
2. The method for detecting boron and phosphorus impurities in hydrogen recovery from photovoltaic polycrystalline silicon according to claim 1, characterized in that: In step a, the concentration of the silver nitrate solution is 0.04~0.06 g / L.
3. The method for detecting boron and phosphorus impurities in hydrogen recovery from photovoltaic polycrystalline silicon according to claim 1, characterized in that: In step a, the absorption bottle is made of PFA.
4. The method for detecting boron and phosphorus impurities in hydrogen recovery from photovoltaic polycrystalline silicon according to claim 1, characterized in that: In step a, the volume of silver nitrate solution in each absorption bottle is the same, which is 40~60mL.
5. The method for detecting boron and phosphorus impurities in hydrogen recovery from photovoltaic polycrystalline silicon according to claim 1, characterized in that: In step b, the inlet flow rate of the recovered hydrogen gas into the sample absorption bottle is 0.4~0.6 L / min, and the inlet time is 100~140 min.
6. The method for detecting boron and phosphorus impurities in hydrogen recovered from photovoltaic polycrystalline silicon according to claim 1, characterized in that: The boron and phosphorus impurity content in the sample absorption solution in step c and the boron and phosphorus impurity content in the blank solution in step d should be measured at least twice until the relative deviation between the two parallel measurements is no more than 15%, and the average value should be taken.
7. The method for detecting boron and phosphorus impurities in hydrogen recovery from photovoltaic polycrystalline silicon according to claim 1, characterized in that: In step e, the formula for calculating the content of boron and phosphorus impurities in the recovered hydrogen is: ； Where M represents the content of boron or phosphorus impurities in the recovered hydrogen. This indicates the content of boron or phosphorus impurities in the absorbent. This indicates the content of boron or phosphorus impurities in the blank solution of the blank sample vial. This indicates the weight of the sample absorption bottle along with the solution inside. Indicates the weight of the sample absorption bottle. This indicates the volume of recovered hydrogen gas introduced under standard conditions. This indicates the density of hydrogen gas.
8. The method for detecting boron and phosphorus impurities in hydrogen recovery from photovoltaic polycrystalline silicon according to claim 7, characterized in that: Under standard conditions, the volume of recovered hydrogen gas introduced is... The calculation formula is: ； in, This represents the atmospheric pressure value during absorption. Indicates standard temperature. Indicates the intake airflow. Indicates the intake time. Indicates standard pressure. This indicates the temperature at which absorption occurs.