CN112484936B - Method and device for quantitatively monitoring airtight space air tightness - Google Patents
Method and device for quantitatively monitoring airtight space air tightness Download PDFInfo
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
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Abstract
The application discloses a method for quantitatively monitoring airtight space air tightness, which comprises the following steps: a) Measuring a time-dependent change PI (t) of the air pressure inside the closed space and/or a time-dependent change PD (t) of the air pressure difference outside and inside the closed space; b) And calculating the airtight quantitative value S of the airtight space according to the time change rate of the PI (t) and/or the PD (t), wherein S is in direct proportion to the time change rate of the PI (t), and S is in inverse proportion to the PD (t). The method can give quantitative values of the air tightness degree, and provides the possibility of carrying out historical comparison on the air tightness degree of the same object to be tested, the possibility of carrying out transverse comparison on the air tightness degree of the same object to be tested, and the possibility of carrying out transverse comparison even on the air tightness degree of non-same objects to be tested. This solution does not require a great deal of additional investment and is suitable for the overall process monitoring and assessment of the degree of tightness during use of the house or equipment.
Description
Technical Field
The application relates to the field of air tightness detection, in particular to a method and a device for quantitatively monitoring air tightness of a closed space.
Background
Some equipment with waterproof and dustproof requirements not only needs to detect the air tightness before leaving the factory, but also needs to monitor and evaluate the whole air tightness in the use process so as to discover the failure condition of the air tightness as soon as possible, take measures and ensure the use safety. In addition, the air tightness detection is also applied to the field of construction, and has certain air tightness, which is a basic requirement of energy conservation and environmental protection of houses; with the increasing promotion of the living standard of people, the air tightness detection of houses and the whole-course monitoring and evaluation of the air tightness in the use process are the necessary trend of technical development.
The existing technology for detecting the air tightness of the equipment can only generally give classification results, such as passing or failing detection, but cannot give a numerical value representing the air tightness degree. This makes it impossible to perform a historical comparison of the degree of air tightness on the same equipment, and also to perform a lateral comparison of the degree of air tightness on equipment of the same specification, and even more so to perform a lateral comparison of the degree of air tightness on equipment of different specifications.
In addition, a device called a blower door makes it possible to perform quantitative measurements of the tightness of a house. However, during detection, a special device is required to be installed on a door frame of a house, air is blown into the house or blown from the house to reach a certain positive pressure or negative pressure, then the air flow is measured, and finally the ventilation times are calculated according to the volume. This solution requires additional costs and affects the normal use of the house. Obviously, such devices are not suitable for the overall process monitoring and assessment of the degree of tightness during use of the house.
Disclosure of Invention
The invention provides a method and a device for quantitatively monitoring the air tightness of a closed space, which can solve the technical problems by measuring one or two pressure data and then calculating to obtain the air tightness quantitative value of the closed space.
In a first aspect, the present application discloses a method for quantitatively monitoring the air tightness of a closed space, comprising the steps of: a) Measuring a time-dependent change PI (t) of the air pressure inside the enclosed space and a time-dependent change PD (t) of the air pressure difference outside and inside the enclosed space; or measuring PI (t) and a change PO (t) of air pressure outside the closed space, wherein the change PO (t) is related to time, and PD (t) is obtained from PO (t) -PI (t); or measuring PO (t) and PD (t), and obtaining PI (t) from PO (t) -PD (t); b) And calculating the airtight quantitative value S of the airtight space according to the time change rate of the PI (t) and the PD (t), wherein S is in direct proportion to the time change rate of the PI (t), and S is in inverse proportion to the PD (t).
In order to determine the relationship between the airtight quantitative value S and PI (t) and PD (t), the present inventors studied the gas leakage mechanism of the airtight space. The closed space may be notionally a space surrounded by a rigid housing. In an ideal case, when the space is completely airtight, the housing is completely sealed without any gaps or holes, and the outside of the space is not in any gas exchange with the inside. In reality, the housing has more or less gaps and holes through which gas exchange takes place; when the air pressure difference exists between the outside and the inside of the space, the air pressure in the closed space can change along the direction of the pressure difference until the pressure difference is 0. The gaps and the holes can be equivalent to a pore, and it is easy to understand that the smaller the pore is, the slower the gas exchange is, and the higher the air tightness is; the larger the pores, the faster the gas exchange, and the lower the gas tightness; in addition, the same size of pores, which appear on a housing with a larger volume, have a higher air tightness than on a housing with a smaller volume, and the latter have a lower air tightness. In order to scientifically measure the degree of tightness, some industries may employ the number of air changes per hour caused by gas exchange entirely by the pores as a quantitative value for measuring the degree of tightness. The number of ventilation per hour can also be interpreted as the inverse of the time for one ventilation of the gas throughout the space.
The relation between the flow q entering the closed space through the pore and the pressure difference PD inside the closed space is obtained by a related formula of fluid mechanics:
q＝K*A*PD m ；
k: coefficients related to the shape and size of the aperture;
a: equivalent flow area of the aperture;
m: the index is determined by the shape of the pores, i.e. the relative size of the pore diameter and pore length. M is more than or equal to 0.5 and less than or equal to 1. For thin-walled small holes m=0.5, for elongated holes m=1, short holes are interposed between them; when the ratio of the channel length to the aperture of the aperture is less than or equal to 0.5, the aperture is called a thin-wall aperture; when the ratio of the channel length to the aperture of the small hole is greater than 4, it is called an elongated hole; when the ratio of the channel length to the pore diameter of the small pores is greater than 0.5 and equal to or less than 4, it is called a short pore.
The above formula can be simplified as formula 1:
q＝k1*PD(t) m ；
the equation is also derived from the Kelarong equation:
PI*V＝R*T*Q；
t: thermodynamic temperature;
r: a gas constant;
q: the amount of gas in the enclosed space;
PI: air pressure within the enclosed space;
assuming that the internal temperature and volume of the enclosed space are unchanged, the above formula can be simplified as:
Q＝k2*PI；
the two sides derive time to get equation 2:
assuming that the change in air pressure inside the closed space is entirely caused by air exchange through the pores, equation 3 is obtained from equations 1 and 2:
air flow at differential pressure PD calculates the time T taken for a full air ventilation pass:
the quantitative value S of the air tightness is defined as the ventilation times, which is the reciprocal of T, and the formula 4 is obtained:
；
namely:
k1＝k2*PD(t) 1-m *S；
the result is given by the following formula 3:
；
equation 5 is obtained:
the following facts can be derived from the above studies and formulas: the ventilation times of the enclosed space are only equal to the time of the air pressure in the enclosed space under the condition that the volume and the temperature of the enclosed space are unchanged and the air pressure change in the enclosed space is completely caused by the air exchange through the poresRate of changeAnd the ratio of the air pressure difference PD (t) between the outside and the inside of the enclosed space.
Taking the ventilation times of the closed space as the airtight quantitative value S representing the closed space means that the airtight quantitative value S can be calculated by only measuring the time-dependent changes PI (t) and PD (t) of two pressure values, wherein S is in direct proportion to the time change rate of PI (t), and S is in inverse proportion to PD (t). In practice, the function of PI (t) and PD (t) may be measured, and the air tightness quantitative value S may be calculated as well, for example, the change in resistance of the strain resistor due to the change in air pressure.
The beneficial effects of the technical scheme are quite obvious: quantitative values of the air tightness can be obtained, and the quantitative values of the air tightness are only related to the time-related changes PI (t) and PD (t) of two pressure values and are not related to other parameters of the closed space, so that the possibility is provided for transverse comparison of the air tightness degree of the closed space to be tested of the same type and different types. Through continuous monitoring of PI (t) and PD (t), historical changes of airtight quantitative values of the airtight space can be obtained, and the trend of gradual failure of the airtight caused by aging of the sealing device can be predicted and estimated.
In order to facilitate the operation of the microprocessor, S can be calculated in step b) from discrete sampled values of PI (t) and PD (t), and the algorithm can refer to a numerical differential calculation method.
The present application provides a formula in step b) that can calculate S from discrete sampled values of PI (t) and PD (t): wherein PI is 1 、PI 2 ...PI n Is an array obtained by sampling PI (t) for a plurality of times within a certain time period, PD 1 、PD 2 ...PD n Sampling PD (t) for several times in a certain time periodThe resulting array, Δt, is the sampling interval time, n is the total number of samples.
The above formula for calculating S from discrete sample values of PI (t) and PD (t) is derived as follows:
taking the limit value of the PI (t) time change rate:
；
obtained from equation 5:
；
s in a period of time is calculated by adopting discrete sampling values to obtain a formula 6:
the mechanism of air leakage may be different between positive and negative pressure in the enclosed space, leading to possible differences in S, and in step b), PI may be selected for a certain period of time in which PD (t) is all positive or all negative 1 、PI 2 ...PI n And PD 1 、PD 2 ...PD n And (S) calculating to obtain the quantitative value of the air tightness of the closed space under negative pressure or positive pressure. This step has the further advantage that: PI during the period when PD (t) is all positive or all negative 1 、PI 2 ...PI n Will be monotonic, thus PI 1 、PI 2 ...PI n The larger range can be accumulated, which is beneficial to improving the operation precision of the formula 6.
ACH and ACH50 are one of the indicators commonly used in some fields as a measure of air tightness, and the method further comprises the following steps: c) ACH, namely the ventilation times per hour, is calculated, and the calculation formula is as follows:wherein the time of the time rate of change of PI (t)The units are hours, and the units of PI (t) and PD (t) are the same; ACH is calculated from discrete sampled values of PI (t) and PD (t), and the formula is: />Δt is in hours, PI 1 、PI 2 ...PI n And PD 1 、PD 2 ...PD n Is the same in units of (a).
Further, the method also comprises the following steps: d) The ACH50, i.e. the number of ventilation per hour when the air pressure difference between the outside and the inside of the enclosed space is 50 pascals, is calculated as:wherein m is more than or equal to 0.5 and less than or equal to 1, P50 is a pressure conversion value when the pressure difference between the outside air and the inside air of the closed space is 50 Pa, and the units of P50, PI (t) and PD (t) are the same; the equation for calculating ACH50 from discrete sample values of PI (t) and PD (t) is: /> Wherein, the unit of Deltat is hour, P50 and PI 1 、PI 2 ...PI n And PD 1 、PD 2 ...PD n Is the same in units of (a).
The formula for calculating ACH50 is derived as follows:
obtained from equation 4:
k1＝k2*P50 1-m *ACH50；
the result is given by the following formula 3:
；
equation 7 is obtained:
；
taking a limit value:
；
obtained from equation 7:
；
the ACH50 for a period of time is calculated using discrete sample values, yielding equation 8:
in some practical applications, the physical meaning of the above quantitative value of air tightness is not emphasized, in other words, in these applications, the number of ventilation times is not required, but only one quantitative value of air tightness which can be compared is required. For this reason, the application also discloses a method for quantitatively monitoring the airtight of the airtight space, which comprises the following steps: a) Measuring a time-dependent change PI (t) of the air pressure inside the closed space; b) And calculating the airtight quantitative value S of the airtight space according to the time change rate of the PI (t), wherein the S is in direct proportion to the time change rate of the PI (t).
The beneficial effects of this technical scheme are: in the same measurement time period, the external air pressure of the closed space has the same change, for example, a plurality of houses in the same area in one day have the same air pressure change, and the air tightness degree can be measured by comparing the air tightness quantitative values S of a plurality of closed spaces only by measuring the change PI (t) of the internal pressure value and the time correlation.
To facilitate the operation of the microprocessor, in step b) S is calculated from the discrete sample values of PI (t).
The present application providesA formula for calculating S using discrete sample values of PI (t) is shown:wherein PI is 1 、PI 2 ...PI n The array is obtained by sampling PI (t) for a plurality of times in a certain time period, delta t is sampling interval time, and n is total sampling times.
Further, in step b), PI (t) is selected to have a start point value and an end point value of PI (t) of minimum value and maximum value or a certain period of time of maximum value and minimum value, respectively 1 、PI 2 ...PI n S is calculated. The step can accumulate larger range, which is beneficial to improving the operation precision of the calculation formula.
Similarly, in some applications, a quantitative value of the tightness can also be obtained by measuring the pressure difference between the outside and the inside of the closed space. For this reason, the application also discloses a method for quantitatively monitoring the airtight of the airtight space, which comprises the following steps: a) Measuring a time-dependent change PD (t) in the air pressure difference between the outside and the inside of the closed space; b) From PD (t), a quantitative value S of the airtight space is calculated, S being inversely proportional to PD (t).
The beneficial effects of this technical scheme are: in the same measurement time period, the external air pressure of the closed space has the same change, and only the pressure difference PD (t) between the outside and the inside is measured, so that the air tightness degree can be measured by comparing the air tightness quantitative values S of a plurality of closed spaces.
To facilitate the operation of the microprocessor, in step b) S is calculated from the discrete sample values of PI (t).
The formula for calculating S from the discrete sample values of PD (t) from formula 6 is:wherein PD 1 、PD 2 ...PD n The PD (t) is sampled for a plurality of times in a certain time period to obtain an array, wherein Deltat is sampling interval time, and n is total sampling times.
Further, in step b), PD (t) is selected to be all positivePD for a certain period of time where the value or all are negative 1 、PD 1 ...PD n S is calculated.
In some implementations, the airtight status may be classified. For this purpose, the application also discloses a method for quantitatively monitoring the airtight of the closed space, which comprises the following steps besides the steps of the method: e) S is smaller than a threshold value, the air tightness is indicated to be effective or the air tightness is too high; or S is greater than a threshold, indicating a failure or too low tightness.
In some implementations, quantitative values of the air tightness of a plurality of closed spaces can be compared. For this purpose, the application also discloses a method for quantitatively monitoring the airtight of the closed space, which comprises the following steps besides the steps of the method: f) Comparing the quantitative values S of the air tightness of the plurality of closed spaces, which are measured in the same time period and calculated by the same step b), wherein the S is smaller and the air tightness is higher.
In some applications, natural changes in atmospheric pressure may be utilized for hermeticity monitoring. Even in the same place, the atmospheric pressure is subjected to a more remarkable but slow change period all the year round or all the day round, and the airtight quantitative value of the closed space can be measured by utilizing the change period of the atmospheric pressure. For this purpose, the application also discloses a method for quantitatively monitoring the airtight of the closed space, which comprises the following steps besides the steps of the method: g) The measurement is made over a period of time long enough for a significant imbalance in air pressure to occur between the outside and inside of the enclosed space.
In some implementations, the air pressure inside or outside the enclosed space can be changed using existing means. For this purpose, the application also discloses a method for quantitatively monitoring the airtight of the closed space, which comprises the following steps besides the steps of the method: h) The action is exerted so that the air pressure outside and inside the enclosed space is significantly unbalanced, and the mode of the action comprises one of the following steps: inflating, pumping, heating and cooling. In a system already provided with a fan, it is possible to have a significant imbalance in the air pressure outside and inside the enclosed space. It should be noted, however, that in order to calculate the quantitative value of the air tightness correctly, the measurement of the pressure value should be carried out during the period of time chosen for which the fan is turned off, since one of the assumed conditions deduced by the calculation formula of S is that the variation of the air pressure inside the closed space is entirely caused by the porosity of the casing. Of course, if the air flow of the fan is known, it is also possible to make measurements during operation of the fan and to remove the effect of the air flow of the fan when calculating S.
Finally, the application also discloses a device for quantitatively monitoring the airtight property of the airtight space, which comprises: a processor and a memory; the memory is used for storing program instructions; the processor executes the program instructions in the memory to implement a method for quantitatively monitoring the airtight of the enclosed space.
Further, the method further comprises the following steps: one or more pressure sensors; a pressure sensor for measuring the air pressure in the closed space and the air pressure difference between the outside and the inside of the closed space; or measuring the air pressure inside the enclosed space and the air pressure outside the enclosed space; or measuring the air pressure outside the closed space and the air pressure difference between the outside and the inside of the closed space; or measuring the air pressure inside the enclosed space; or measuring the air pressure difference between the outside and the inside of the closed space.
The beneficial effects of the technical scheme that this application provided are as follows: the method and the device for quantitatively monitoring the airtight space can give quantitative values of the airtight degree, and provide the possibility of carrying out historical comparison on the airtight degree of the same object to be tested, the possibility of carrying out transverse comparison on the airtight degree of the same object to be tested, and the possibility of carrying out transverse comparison even on the airtight degree of non-same objects to be tested. This solution does not require a great deal of additional investment and is suitable for the overall process monitoring and assessment of the degree of tightness during use of the house or equipment.
Drawings
Fig. 1 shows the relationship between the air pressure inside the closed space, the air pressure outside the closed space, and the air pressure difference between the outside and inside the closed space with time.
FIG. 2 shows a comparison of the time dependence of the air pressure inside and the air pressure difference between the outside and inside under the same external air pressure in two airtight spaces having different air tightness.
Fig. 3 is a device for quantitatively monitoring the airtight of an airtight space by measuring the air pressure inside the airtight space and the air pressure difference between the outside and the inside of the airtight space.
Figure 4 shows a device for quantitatively monitoring the tightness of a closed space by measuring the air pressure inside the closed space.
Fig. 5 quantitatively monitors the airtight of the airtight space by measuring the air pressure difference between the outside and inside of the airtight space.
Detailed Description
Fig. 1 depicts the relationship between the air pressure PI inside the sealed space, the air pressure difference PD between the outside and the inside, and the air pressure PO outside the sealed space with time, with the horizontal axis being the time axis and the vertical axis being the pressure. When PO rises, PD rises to be a positive value, and gas exchange occurs in the pores of the shell of the closed space, so that PI rises along with PO, but with a certain hysteresis; the PO starts to fall back after rising to the maximum value, and the PI will continue to rise until PI and PO meet at t1, at which point the pressure difference PD is 0, because the pressure difference PD still exists.
Fig. 2 depicts the air pressure inside two closed spaces having different degrees of air tightness PI1 and PI2, respectively, under the same outside air pressure PO, and the difference between the outside air pressure and the inside air pressure inside the two closed spaces PD1 and PD2, respectively. PI2 rises faster than PI1 and intersects PO earlier at t0, while PD2 rises less in magnitude than PD1 and drops back to 0 earlier at t 0. Obviously, the airtight spaces represented by PI1 and PD1 have higher airtightness than the airtight spaces represented by PI2 and PD2.
In the first embodiment, as shown in fig. 3, the air tightness of the closed space is quantitatively monitored by measuring the air pressure inside the closed space and the air pressure difference between the outside and the inside of the closed space.
The device 10 for quantitatively monitoring the airtight property of the closed space is placed inside the living room 1. The device 10 for quantitatively monitoring the airtight property of the closed space comprises a microcontroller 5, a memory 6, a first pressure sensor 7, a second pressure sensor 8 and an indication module 9. The microcontroller 5 is connected to a first pressure sensor 7, a second pressure sensor 8, an indication module 9 and a memory 6. The memory 6 stores program instructions for the acquisition of pressure measurements and for the calculation of the quantitative value S of the tightness.
The first pressure sensor 7 is a high-precision pressure-isolating pressure sensor, and the model is BMP380; the vent hole 71 of the first pressure sensor 7 is communicated with the interior of the living room 1, and senses the air pressure in the living room 1; the second pressure sensor 8 is also a high-precision pressure-isolating pressure sensor, and the model is BMP380; the vent hole 81 of the second pressure sensor 8 is communicated with the outside of the living room 1, and senses the air pressure outside the living room 1; the microcontroller 5 respectively collects data from the first pressure sensor 7 and the second pressure sensor 8 once every 10 seconds to obtain an array PI 1 、PI 2 ...PI n Sum array PO 1 、PO 2 ...PO n Obtaining an array PD through calculation 1 、PD 2 ...PD n N is 4320, i.e. 12 hours of sampled data.
Microcontroller 5 according to PI 1 、PI 2 ...PI n And PD 1 、PD 2 ...PD n The formula for calculating the air tightness quantitative value S is as follows: Δt was 0.0027778 hours.
Each time the microcontroller 5 collects data, i.e. adds one data at the tail of the original array and removes one data at the head of the array, then the array is used for calculating S, so that S can be calculated every 10 seconds.
PD within 12 hours can also be selected 1 、PD 2 ...PD n And (3) calculating the numerical value S in the time period with all positive values or all negative values to obtain the quantitative value of the air tightness of the living room 1 under the negative pressure or the positive pressure.
ACH, i.e. the number of ventilation per hour, can also be calculated as:Δt is in hours, PI 1 、PI 2 ...PI n And PD 1 、PD 2 ...PD n Is the same in units of (a).
The ACH50, i.e. the number of ventilation per hour when the air pressure difference between the outside and the inside of the enclosed space is 50 pascals, can also be calculated by the formula:Δt was 0.0027778 hours, P50, PI 1 、PI 2 ...PI n And PD 1 、PD 2 ...PD n Is the same in units of (a).
The indication module 9 is provided with an LCD display on which the quantitative value S of the tightness is displayed. When S is larger than the threshold value, the air tightness of the LCD display screen is too low; when S is smaller than the threshold value, the LCD display screen displays that the air tightness is too high.
In the first embodiment of the present application, the measurement time period is set to 12 hours, and in this longer time period, the atmospheric pressure will change significantly enough, so that the quantitative value S of the air tightness of the living room can be calculated.
In practical application, for a system with a fan, if the fan is skillfully utilized, the measuring time can be shortened, and the measuring efficiency can be improved. The fan can be started to inflate the inside of the room, the air pressure in the room is changed in a short time, data acquisition is carried out in a period of time after the fan is stopped, and the air tightness quantitative value S of the room can be calculated in a short time.
In the second embodiment, as shown in fig. 4, the air tightness of the closed space is quantitatively monitored by measuring the air pressure in the closed space.
The device 20 for quantitatively monitoring the airtight property of the closed space is placed inside the waterproof apparatus 2. The device 20 for quantitatively monitoring the tightness of the enclosed space comprises a microcontroller 5, a memory 6, a first pressure sensor 7 and an indication module 9. The microcontroller 5 is connected to the pressure sensor 7, the indicating module 9 and the memory 6. The memory 6 stores program instructions for the acquisition of pressure measurements and for the calculation of the quantitative value S of the tightness.
The pressure sensor 7 is a high-precision pressure-isolating pressure sensor, and the model is BMP380; the vent hole 71 of the pressure sensor 7 is communicated with the inside of the waterproof equipment 2, and senses the air pressure inside the waterproof equipment 2; the microcontroller 5 collects data from the pressure sensor 7 once every 10 seconds to obtain an array PI 1 、PI 2 ...PI n N is 4320, i.e. 12 hours of sampled data.
Microcontroller 5 according to PI 1 、PI 2 ...PI n The formula for calculating the air tightness quantitative value S is as follows:Δt was 0.0027778 hours.
Each time the microcontroller 5 collects data, i.e. adds one data at the tail of the original array and removes one data at the head of the array, then the array is used for calculating S, so that S can be calculated every 10 seconds.
Minimum and maximum values or maximum and minimum values within 12 hours can be selected as PI 1 And PI (proportional integral) n S is calculated.
The indication module 9 is provided with an LED alarm lamp, and when S is larger than a threshold value, the LED alarm lamp displays flashing to indicate that the air tightness is invalid or is too low.
In the second embodiment of the present invention, the calculated air tightness quantitative value S may be uploaded to the server for comparison by the equipment placed under the same area and under the atmospheric pressure, and the air tightness of S is relatively low.
In the third embodiment, as shown in fig. 5, the air tightness of the closed space is quantitatively monitored by measuring the air pressure difference between the outside and the inside of the closed space.
The device 30 for quantitatively monitoring the airtight property of the closed space is placed inside the dust-proof equipment 3. The device 30 for quantitatively monitoring the airtight property of the closed space comprises a microcontroller 5, a memory 6, a pressure sensor 7 and an indication module 9. The microcontroller 5 is connected to the pressure sensor 7, the indicating module 9 and the memory 6. The memory 6 stores program instructions for the acquisition of pressure measurements and for the calculation of the quantitative value S of the tightness.
The pressure sensor 7 is a differential pressure type pressure sensor; one vent hole 71 of the pressure sensor 7 is communicated with the inside of the dust-proof device 3, and senses the air pressure inside the dust-proof device 3; the other vent hole 72 of the pressure sensor 7 is communicated with the outside of the dustproof device 3, and senses the air pressure inside the dustproof device 3; the microcontroller 5 collects data from the pressure sensor 7 once every 10 seconds to obtain an array PD 1 、PD 2 ...PD n N is 4320, i.e. 12 hours of sampled data.
The microcontroller 5 is according to PD 1 、PD 2 ...PD n The formula for calculating the air tightness quantitative value S is as follows:Δt was 0.0027778 hours.
Each time the microcontroller 5 collects data, i.e. adds one data at the tail of the original array and removes one data at the head of the array, then the array is used for calculating S, so that S can be calculated every 10 seconds.
The data calculation S may be selected for a period of time that is either all positive or all negative within 12 hours.
The indication module 9 is provided with an LED alarm lamp, and when S is larger than a threshold value, the LED alarm lamp displays flashing to indicate that the air tightness is invalid or is too low.
In the third technical scheme of the present embodiment, the calculated air tightness quantitative value S can be uploaded to the server for comparison by the equipment placed under the atmospheric pressure in the same area, and the air tightness of the smaller S is higher.
Claims (12)
1. A method for quantitatively monitoring the air tightness of a closed space, comprising the following steps:
a) Measuring a time-dependent change PI (t) of the air pressure inside the enclosed space and a time-dependent change PD (t) of the air pressure difference outside and inside the enclosed space; or measuring PI (t) and a time-dependent change PO (t) of air pressure outside the closed space, and obtaining PD (t) from PO (t) -PI (t); or measuring PO (t) and PD (t), and obtaining PI (t) from PO (t) -PD (t);
b) And calculating the airtight quantitative value S of the airtight space according to the time change rate of PI (t) and PD (t), wherein S is in direct proportion to the time change rate of PI (t), and S is in inverse proportion to PD (t).
2. Method according to claim 1, characterized in that in step b) S is calculated from discrete sampled values of PI (t) and PD (t).
3. The method according to claim 2, characterized in that in step b) the formula for calculating S from the discrete sampled values of PI (t) and PD (t) is:
，
wherein PI is 1 、PI 2 ...PI n Is an array obtained by sampling PI (t) for a plurality of times within a certain time period, PD 1 、PD 2 ...PD n Is an array obtained by sampling PD (t) for a plurality of times, delta t is sampling interval time, and n is total sampling times.
4. A method according to claim 3, characterized in that in step b) PI is selected for a certain period of time in which PD (t) is all positive or all negative 1 、PI 2 ...PI n And PD 1 、PD 2 ...PD n And S, calculating to obtain the quantitative value of the air tightness of the closed space under negative pressure or positive pressure.
5. The method of claim 1, further comprising the step of:
c) ACH, namely the ventilation times per hour, is calculated, and the calculation formula is as follows:
，
wherein, the time unit is hour, and the units of PI (t) and PD (t) are the same;
the equation for calculating ACH from discrete sample values of PI (t) and PD (t) is:
，
wherein Δt is in hours, PI 1 、PI 2 ...PI n And PD 1 、PD 2 ...PD n Is the same in units of (a).
6. The method of claim 1, further comprising the step of:
d) The ACH50, namely the number of ventilation times per hour when the air pressure difference between the outside and the inside of the closed space is 50 pascals, is calculated by the following formula:
，
wherein m is more than or equal to 0.5 and less than or equal to 1, P50 is a pressure conversion value when the air pressure difference between the outside and the inside of the closed space is 50 Pa, and units of P50, PI (t) and PD (t) are the same;
the equation for calculating ACH50 from discrete sample values of PI (t) and PD (t) is:
，
wherein, the unit of Deltat is hour, P50 and PI 1 、PI 2 ...PI n And PD 1 、PD 2 ...PD n Is the same in units of (a).
7. A method of quantitatively monitoring the tightness of a closed space comprising the method of any of claims 1 to 6 and the steps of:
e) S is smaller than a threshold value, the air tightness is indicated to be effective or the air tightness is too high; or S is greater than a threshold, indicating a failure or too low tightness.
8. A method of quantitatively monitoring the tightness of a closed space comprising the method of any of claims 1 to 6 and the steps of:
f) Comparing the quantitative values S of the air tightness of the plurality of closed spaces, which are measured in the same time period and calculated by the same step b), wherein the S is smaller and the air tightness is higher.
9. A method of quantitatively monitoring the tightness of a closed space comprising the method of any of claims 1 to 6 and the steps of:
g) The measurement is made for a period of time long enough so that there is a significant imbalance in air pressure between the outside and the inside of the enclosure.
10. A method of quantitatively monitoring the tightness of a closed space comprising the method of any of claims 1 to 6 and the steps of:
h) The action is exerted so that the air pressure outside and inside the closed space is significantly unbalanced, and the mode of the action comprises one of the following steps: inflating, pumping, heating and cooling.
11. A device for quantitatively monitoring the tightness of a closed space, comprising: a processor and a memory;
the memory is used for storing program instructions; the processor executes program instructions in the memory to implement the method of any one of claims 1 to 10.
12. The apparatus as recited in claim 11, further comprising: one or more pressure sensors;
the pressure sensor may be configured to detect a pressure in the fluid,
measuring the air pressure inside the closed space and the air pressure difference between the outside and the inside of the closed space;
or measuring the air pressure inside the enclosed space and the air pressure outside the enclosed space;
or measuring the air pressure outside the closed space and the air pressure difference between the outside and the inside of the closed space.
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