Air-conditioning system regulation method for indoor environmental aerosol safety

Abstract

The present invention belongs to the field of air conditioning system control, and discloses an air conditioning system control method for indoor environmental aerosol safety, including the following steps: S1, establishing a pathogen-containing aerosol concentration control model for ventilation and air conditioning places; S2, a probability model for indoor personnel inhaling pathogen-containing aerosols; S3, proposing a safe duration of indoor environmental aerosols in air-conditioned public places; S4, proposing an air conditioning system antivirus control strategy based on the safe duration of indoor environmental aerosols. The method of the present invention not only adds a disinfection device to ensure the cleanliness of the air supply air during the one-time return air operation of the air conditioning system, but also more reasonably regulates the system air supply volume through the indoor environmental aerosol safe duration, so that the antivirus control effect of the system can be quantitatively analyzed, but also avoids the influence of the hysteresis and regional differences of the infection dose in the Wells-Riley model, introduces the influence of personnel protection and disinfection devices, and makes the antivirus control of the air conditioning system more in line with engineering practice.

Description

Technical Field

[0001] The present invention belongs to the field of air-conditioning system control, and particularly relates to a method for regulating and controlling an air-conditioning system for indoor environmental aerosol safety. Background Art

[0002] In recent years, the Hygienic Specification for the Operation and Management of Air-conditioning and Ventilation Systems in Office and Public Places (Standard No. WS 696-2020) stipulates that indoor air circulation needs to be strengthened in crowded public places. The all-air air-conditioning systems in public places in low-risk areas should operate with the maximum fresh air volume during operation, and the all-air air-conditioning systems in medium- and high-risk areas should close the return air, or the return air can be reduced under the premise of installing an effective disinfection device.

[0003] Increasing the fresh air volume and the supply air volume will inevitably lead to an increase in the power consumption of the air-conditioning system fan and the energy consumption of the chiller. However, the standard limits of the fresh air volume and the supply air volume have not been specified in the specification, which makes it more difficult to regulate and control the energy conservation of the air-conditioning system, and the safety of the indoor environment created by the system is still unknown. For this reason, many domestic and foreign researchers have proposed control strategies for air-conditioning systems by calculating the relationship between the risk of personnel infection and the supply air volume based on the Wells-Riley model (Riley E C, MURPHY G, RILEY R. Airborne spread of measles in a suburban elementary school[J]. American Journal of Epidemiology, 1978, 107(5): 421-432). However, the infection dose in the Wells-Riley model is inversely calculated based on the reported number of infected people in different regions, and its value has hysteresis and regional differences. Therefore, the above control strategies are not convenient for guiding the anti-virus regulation of air-conditioning systems in various regions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for regulating and controlling an air-conditioning system for indoor environmental aerosol safety, which is convenient for guiding the regulation of the supply air volume of a virus all-air air-conditioning system. By analyzing the transmission process of pathogen-containing aerosols in the air-conditioning room and the air-conditioning pipeline, an indoor pathogen-containing aerosol concentration control model is established; by analyzing the breathing process of personnel, a probability model of personnel inhaling pathogen-containing aerosols is established; by combining the above two models, the indoor environmental aerosol safety duration in the air-conditioning environment of public places is proposed to measure the safety of the indoor environment created by the air-conditioning system; finally, the aerosol safety duration is used as one of the control parameters of the air-conditioning system, and an air-conditioning system control strategy is proposed.

[0005] The technical solution of the present invention is as follows:

[0006] A method for regulating and controlling an air-conditioning system for indoor environmental aerosol safety, the steps are as follows:

[0007] S1. Establish a control model for the concentration of pathogen-containing aerosols in ventilation and air-conditioning premises

[0008] The main sources of pathogen-containing aerosol particles indoors are generated by the breathing of indoor patients and brought in by the air supply of the air conditioner. The main destinations are being absorbed by people, natural death, and leaving the indoor through the air exhaust of the air conditioner;

[0009] According to the situation of people wearing masks indoors in public places, introduce the personnel protection coefficient β, 0 ≤ β ≤ 1, which represents the proportion of pathogen-containing aerosol particles passing through the protection measures. When people do not wear masks, β = 1. Then the change in the number of pathogen-containing aerosol particles indoors is:

[0010]

[0011] where, V room is the indoor air volume, i.e., the room volume, m 3 ; c(τ) is the average concentration of pathogen-containing aerosols in the air at various places indoors at time τ, particles / m 3 ; c(τ) is related not only to time but also to the spatial coordinates. Here, c(τ) refers to the average concentration of pathogen-containing aerosol particles at various places indoors at a certain moment; t is time, h; is the air volume sent into the room per unit time, m 3 / h; c s (τ) is the concentration of pathogen-containing aerosol particles in the supply air, particles / m 3 ; β is the personnel protection coefficient. Here, it is considered that all people indoors adopt the same hygiene protection measures; n(t) is the number of indoor infected people at time t; is the air volume exhaled by a person, which is equal to the inhaled air volume, m 3 / (h·person); c p (τ) is the concentration of pathogen-containing aerosol particles in the exhaled air of a patient, particles / m 3 ; is the air volume discharged from the room per unit time, m 3 / h; is the reduction in the number of pathogen-containing aerosol particles caused by natural death at time τ, particles / h; N(τ) is the total number of people indoors at time τ;

[0012] When the indoor air change rate reaches 5 times, the concentration of pathogen-containing aerosol particles reaches a steady state; since the virus half-life is 1.2 h, when the indoor air change rate exceeds 3 times, the reduction in the number of pathogen-containing aerosols due to natural death can be ignored; and the average inspiratory volume of a single person's average breathing is 0.5 L, then the exhaust air volume is much larger than the inspiratory volume of indoor people; when the air-conditioning system is equipped with a disinfection device, let the protection coefficient of the air-conditioning system be β f , 0 ≤ βf ≤1, indicating the ratio of pathogen-containing aerosols passing through the air conditioning system. Therefore, for the full air conditioning system with a fresh air ratio of α, the concentration of pathogen-containing aerosols in the indoor air, i.e., the steady-state concentration term submodel, is:

[0013]

[0014] S2. Probability model of indoor personnel inhaling aerosols containing pathogens

[0015] It is assumed that the aerosol particles containing pathogens are dispersed into the indoor air immediately after being exhaled by the patient and are randomly distributed, and the total number of aerosol particles and the number of aerosol particles containing pathogens remain unchanged; since the order of magnitude of the total number of aerosol particles in the indoor air and the total number of aerosol particles discharged by a person in one breathing process is much larger than the order of magnitude of the probability of a single aerosol particle being inhaled, the probability of a person inhaling aerosol particles containing pathogens follows a Poisson distribution:

[0016]

[0017] Where P(τ) is the probability of a person inhaling aerosol particles containing pathogens when staying indoors for a continuous period of τ; V1 is the volume of gas inhaled by the indoor person, m 3 ; τ is the continuous stay time of the personnel in the room, h; τ0 is the average time taken by the personnel to breathe once, h; c is the average concentration of pathogen-containing aerosols in the air at various places in the room at time τ, p / m 3 ;

[0018] S3. Propose the safe duration of aerosol in indoor air-conditioning environment in public places

[0019] Define an indoor environment where the probability of a person inhaling aerosol particles containing pathogens does not exceed 5% as a safe and healthy environment. The maximum continuous stay time of a person indoors should not exceed the indoor environment aerosol safety time τ safe ; Using the method of steps S1 and S2, the indoor environment aerosol safety duration is used as an evaluation index for measuring air safety in public places and should satisfy formula (4):

[0020]

[0021] When the air conditioning system provides different fresh air volumes and supply air volumes, the created indoor environment has different indoor environmental aerosol safety durations;

[0022] S4. Propose an anti-virus control strategy for air conditioning systems based on the safe duration of indoor environmental aerosols

[0023] The control parameters of the comfort all-air air conditioning system include the indoor temperature and humidity of the air-conditioned room, the indoor CO2 concentration, and the indoor positive pressure. During the virus prevention and control period, there is additionally the safe duration of the indoor environment aerosol in the air-conditioned room;

[0024] The specific control steps are as follows:

[0025] S41. Calculation method of the fresh air ratio in the air-conditioned room

[0026] Calculate the fresh air ratio of the room according to the deviation between the measured value and the set value of the indoor CO2 concentration;

[0027] S42. Control of the opening and closing of the disinfection device

[0028] When a virus appears locally, the maintenance and management personnel of the air conditioning system turn on the disinfection device in the air conditioning system until the local virus is eliminated and then turn it off. The value of β f is related to the filtration efficiency of the disinfection device; at other times, the disinfection device is always in the off state, and β f = 1;

[0029] S43. Calculation method of the air supply volume in the air-conditioned room

[0030] Calculate the required fresh air volume of the room according to the method in step S41, determine the value of β f according to step S42. The personnel protection coefficient β is determined according to the wearing situation of masks by the people in the room. The number of indoor infected persons is the rounded value of the product of the total number of people in the room and the average initial infection rate of 2.2% in Chinese cities (Wang J, Huang J, Feng Z, et al. Occupant-density-detection based energy efficient ventilation system: Preventionofinfection transmission[J]. ENERGY AND BUILDINGS, 2021, 240.). When the product result is less than 1, it is considered that there is 1 infected person in the room; Therefore, combining the above parameters and the method in step S3, calculate the required air supply volume of each room and the total air supply volume of the air conditioning system according to the safe duration of the indoor environment aerosol;

[0031] S44. CO2 concentration control strategy for the air-conditioned room

[0032] Calculate the fresh air ratio of the air conditioning system according to the total fresh air volume calculated by the method in step S41 and the total air supply volume calculated by the method in step S43, and adjust the opening of the fresh air valve according to the fresh air ratio so that the indoor CO2 concentration reaches the set value requirement, and the deviation cannot exceed the allowable error range; adjust the opening of the return air valve so that the sum of its opening and the opening of the fresh air valve is 1;

[0033] S45. Indoor environmental aerosol safety duration control strategy

[0034] Adjust the air valves in the terminal variable air volume boxes according to the calculated air supply volumes of each room in the method of step S43 to make the air supply volume meet the set value requirements; adjust the frequency of the supply fan according to the static pressure of the reference point at the end of the main air duct, so that the static pressure of the reference point is maintained at its set value, and the deviation cannot exceed the allowable error range; the time order of the adjustment process of the variable air volume box is greater than that of the adjustment process of the supply fan frequency;

[0035] S46. Indoor positive pressure control strategy for air-conditioned rooms

[0036] To ensure that the air-conditioned room has a certain positive pressure, adjust the speed of the return fan through the feedforward control method according to the set value of the total air supply volume calculated in the method of step S43 and the rated total air volume of the air-conditioning unit;

[0037] S47. Indoor temperature and humidity control strategy for air-conditioned rooms

[0038] Adjust the opening degree of the water valve of the surface cooler of the air-conditioning unit according to the indoor temperature and humidity to change the supply air temperature, so that the indoor temperature and humidity reach the set value, and the deviation cannot exceed the allowable error range.

[0039] An air-conditioning system control method for indoor environmental aerosol safety proposed by the present invention has the beneficial effects that: compared with other air-conditioning systems using disinfection devices, the present invention introduces the purification efficiency of the disinfection device into the control of the air-conditioning system, making the disinfection device an integral part of the air-conditioning system control, rather than just playing the role of providing clean air; compared with the traditional variable air volume air-conditioning system, the present invention not only adds a disinfection device to ensure the cleanliness of the supply air, but also adds a control index for the indoor environmental aerosol safety duration, which can more reasonably control the air supply volume of the air-conditioning system, enabling the anti-virus control effect of the system to be quantitatively analyzed; compared with the Wells-Riley model, the present invention avoids the infection dose by establishing a probability model of the probability of personnel inhaling pathogen-containing aerosols, making the control of the air-conditioning system more effective in preventing viruses in real time, avoiding the influence of regional differences, and introducing the air-conditioning system protection coefficient and personnel protection coefficient, making the anti-virus control of the air-conditioning system more in line with engineering practice. Description of the drawings

[0040] Figure 1 It is a diagram of the transmission process of pathogen-containing aerosols in a constant air volume variable air volume air-conditioning system.

[0041] Figure 2 It is a diagram of the transmission process of pathogen-containing aerosols in an air-conditioned room.

[0042] Figure 3 It is a control loop diagram of the CO2 concentration in an air-conditioned room.

[0043] Figure 4 This is the safety time control loop diagram for the air-conditioned room.

[0044] Figure 5 This is the air supply static pressure control circuit diagram of the air conditioning system.

[0045] Figure 6 This is the indoor positive pressure control circuit diagram of the air-conditioned room.

[0046] Figure 7 This is the indoor temperature control circuit diagram of the air-conditioned room. DETAILED DESCRIPTION

[0047] The specific implementation of the present invention is described in detail below in conjunction with the content of the invention and the accompanying drawings.

[0048] See attached Figure 1 The present invention provides an air conditioning system control method for indoor environment aerosol safety, which is applicable to a full air variable air volume air conditioning system and comprises the following steps:

[0049] S1. Control model of pathogen-containing aerosol concentration in ventilation and air-conditioning places: refer to the attached Figure 2 The main sources of indoor pathogen-containing aerosols are generated by the breathing of indoor patients, and a small amount is brought in by air conditioning. The main destinations are absorption by people, natural death, and leaving the room with air conditioning exhaust. In addition, since people in public places often wear masks, the personnel protection factor β (0≤β≤1) is introduced to represent the proportion of pathogen-containing aerosol particles passing through protective measures. When people do not wear masks, β = 1, then the change in the number of indoor pathogen-containing aerosol particles is:

[0050]

[0051] Among them, V room is the indoor air volume, i.e. the room volume, m 3 ; c(τ) is the average concentration of pathogen-containing aerosols in the air at various locations in the room at time τ, per m 3 The concentration c is not only related to time, but also to the spatial coordinates. Here, the concentration term refers to the average concentration of pathogen-containing aerosol particles in various places in the room at a certain moment; τ is the time, h; is the air volume delivered to the room per unit time, m 3 / h;c s (τ) is the concentration of pathogen aerosol in the supply air, pieces / m 3 β is the personnel protection factor, where it is assumed that all people in the room adopt the same hygiene protection measures; n(τ) is the number of infected people in the room at time τ; is the amount of air a person exhales, which is equal to the amount of air inhaled, m 3 / (h·person);c pis the concentration of pathogens in the exhaled air of a patient, number / m 3 ; is the air volume discharged from the room per unit time, m 3 / h; is the decrease in the number of aerosols containing pathogens caused by natural death at time τ, number / h; N(τ) is the total number of people in the room at time τ.

[0052] When the indoor air change rate reaches 5 times, the concentration of aerosols containing pathogens reaches a steady state. Since the virus half-life is 1.2 h, when the indoor air change rate reaches 3 times, the decrease in the number of aerosols containing pathogens due to natural death can be ignored; and the average inspiratory volume of a single person's one-time breathing is about 0.5 L, so the exhaust air volume is much larger than the inspiratory volume of indoor personnel. When a disinfection device is installed in the air-conditioning system, let the protection coefficient β of the air-conditioning system f (0 ≤ β f ≤ 1) represents the ratio of aerosols containing pathogens passing through the air-conditioning system. Therefore, for the indoor air concentration of aerosols containing pathogens in a all-air air-conditioning system with a fresh air ratio of α, that is, the steady-state concentration term sub-model is:

[0053]

[0054] S2. Probability model of indoor personnel inhaling aerosols containing pathogens: Assume that the aerosols containing pathogens are immediately dispersed into the indoor air and randomly distributed after being exhaled by the patient, and the total number of aerosol particles and the number of aerosol particles containing pathogens always remain unchanged. Since the order of magnitude of the total number of aerosols in the indoor air and the total number of aerosols exhaled during a person's one-time breathing process is much larger than the order of magnitude of the inhalation probability of a single aerosol particle, the probability of personnel inhaling aerosols containing pathogens follows a Poisson distribution:

[0055]

[0056] where P(τ) is the probability that a person inhales aerosols containing pathogens during continuous stay in the room for τ; V1 is the volume of gas inhaled by indoor personnel, m 3 / h;; τ is the continuous stay time of personnel in the room, h; τ0 is the time taken for a person's average one-time breathing, h; c is the average concentration of aerosols containing pathogens in the indoor air at time τ, number / m 3 .

[0057] S3. Safe duration of aerosols in the indoor environment of public place air conditioners: Define the indoor environment where the probability of personnel inhaling aerosols containing pathogens does not exceed 5% as a safe and healthy environment. Then the longest continuous stay time of personnel in the room should not exceed the safe duration τ of indoor environment aerosols safeBy adopting the methods of steps S1 and S2, the safe duration of indoor environmental aerosol, as an evaluation index for measuring the air safety in public places, should satisfy the following calculation formula:

[0058]

[0059] When the air conditioning system provides different fresh air volumes and supply air volumes, the created indoor environment has different safe durations of indoor environmental aerosol.

[0060] S4. Anti-virus control strategy for the air conditioning system based on the safe duration of indoor environmental aerosol: The control parameters of the comfort all-air air conditioning system include the indoor temperature and humidity, indoor CO2 concentration, and indoor positive pressure in the air-conditioned room. During the virus prevention and control period, there is also an additional safe duration of indoor environmental aerosol in the air-conditioned room.

[0061] Combined with the example of the reading room in the library of Dalian University of Technology, the specific control steps are as follows:

[0062] S41. Calculation method for the fresh air ratio in the air-conditioned room

[0063] According to the deviation between the measured value of the indoor CO2 concentration collected by the sensor in real time and the system set value, calculate the fresh air ratio α of the room room , and the calculation method is:

[0064]

[0065] S42. Opening and closing control of the disinfection device

[0066] When a virus appears locally, the maintenance and management personnel of the air conditioning system turn on the disinfection device in the air conditioning system until the local virus is eliminated and then turn it off. The value of β f is related to the filtration efficiency of the disinfection device; at other times, the disinfection device is always in the off state, and β f = 1;

[0067] For the reading room in the example, the disinfection device adopts a low-resistance electrostatic UVC air purification and disinfection device, which is installed between the primary filter section and the surface cooler section of the air handling unit. When the disinfection device is turned on, β f = 0.2;

[0068] S43. Calculation method for the supply air volume in the air-conditioned room

[0069] Calculate the fresh air ratio of each room according to the method in step S41, and determine β according to step S42 fThe value of the personnel protection factor β is determined according to the mask-wearing situation of the personnel in the room. The number of indoor infected persons is the rounded value of the product of the maximum number of people that the room can accommodate and the average initial infection rate of 2.2% in Chinese cities. When the product result is less than 1, it is considered that there is 1 indoor infected person. Therefore, combining the above parameters and the method in step S3, the required air supply volume for each room and the total air supply volume of the air conditioning system can be calculated based on the safe duration of indoor environmental aerosol.

[0070] For the reading room in the example, since the indoor personnel hardly wear masks, β = 1. There are 104 seats in total in the room, and it is considered that the maximum number of people that the room can accommodate is 104. Therefore, the number of indoor infected persons is 104 × 2.2% = 2 people. Therefore, the calculation method of the room air supply volume is as follows:

[0071]

[0072] S44. CO2 concentration control strategy for air-conditioned rooms

[0073] Refer to Appendix Figure 3 , adjust the opening degree of the fresh air valve according to the fresh air ratio calculated in step S41 to make the indoor CO2 concentration reach the set value requirement, and the deviation cannot exceed the allowable error range; adjust the opening degree of the return air valve so that the sum of its opening degree and the opening degree of the fresh air valve is 1;

[0074] For the reading room in the example, when adopting the control strategy of this patent, the highest indoor CO2 concentration is 479.5 ppm, the lowest is 422.5 ppm, and the average is 458.3 ppm, and the indoor air quality is good.

[0075] S45. Control strategy for the safe duration of indoor environmental aerosol

[0076] According to the air supply volume of each room calculated by the method in step S43, refer to Appendix Figure 4 , adjust the valve in the terminal variable air volume box so that the air supply volume reaches the set value requirement. At the same time, refer to Appendix Figure 5 , adjust the frequency of the supply fan according to the static pressure of the reference point at about 1 / 3 of the end of the main air duct, so that the static pressure of the reference point is maintained near its set value, and the deviation cannot exceed the allowable error range. The time order of the adjustment process of the variable air volume box is greater than that of the adjustment process of the supply fan frequency;

[0077] For the reading room in the example, the safe duration of indoor environmental aerosol is taken as 2.2 h, and the control effect of indoor PM2.5 concentration with similar particle size is used to replace the control effect of pathogen-containing aerosol concentration. When adopting the control strategy of this patent, the highest indoor PM2.5 is 30.7 ppm, the lowest is 9.3 ppm, and the average is 15.6 ppm, and the indoor air quality is excellent; the average filtration efficiency of the air conditioning unit for PM2.5 is 84.2%.

[0078] S46. Indoor positive pressure control strategy for air-conditioned rooms

[0079] To ensure a certain positive pressure in the air-conditioned room, refer to the appendix Figure 6 , and adjust the return air fan speed through the feedforward control method based on the total supply air volume set value calculated by the method in step S43 and the rated total air volume of the air-conditioning unit;

[0080] S47. Indoor temperature and humidity control strategy for air-conditioned rooms

[0081] Refer to the appendix Figure 7 , and adjust the opening degree of the chilled water valve of the air-conditioning unit according to the indoor temperature and humidity to change the supply air temperature, so that the indoor temperature and humidity reach the set values, and the deviation cannot exceed the allowable error range;

[0082] For the reading room in the example, when the control strategy of this patent is adopted, the highest indoor temperature is 24.2 °C, the highest relative humidity is 24.65%, the lowest indoor temperature is 21.4 °C, the lowest relative humidity is 22.1%, the average indoor temperature is 22.8 °C, and the average relative humidity is 23.4%. The indoor environmental thermal comfort is good.

[0083] The traditional variable air volume air-conditioning system control method is: turn off the disinfection device; adjust the opening degree of the fresh air valve according to the indoor CO2 concentration; adjust the air valve in the terminal variable air volume box according to the indoor temperature to make the indoor temperature reach the set value, and at the same time adjust the supply air fan speed according to the static pressure at the reference point; adjust the return air fan speed according to the total supply air volume and the rated total air volume of the air-conditioning unit; when the opening degree of the air valve in the variable air volume box is adjusted to the maximum and still cannot meet the requirements of indoor temperature and humidity, adjust the opening degree of the chilled water valve of the air-conditioning unit to adjust the indoor temperature and humidity by changing the supply air temperature.

[0084] For the control method proposed by the present invention, when there is no virus, the air-conditioning system adopts the above traditional variable air volume system control method. When a virus occurs, the air-conditioning system turns on the disinfection device, and the control basis of the air valve in the variable air volume box changes from the indoor temperature to the aerosol safety duration, and the indoor temperature and humidity are only adjusted by changing the supply air temperature, and the control methods of other equipment remain unchanged. The control sequence of all equipment is carried out in the above steps in turn.

Claims

1. An air-conditioning system control method for indoor environmental aerosol safety, characterized in that, The steps are as follows: S1. Establish a control model for pathogen-containing aerosol concentration in ventilation and air-conditioning places: The main sources of indoor aerosol particles containing pathogens are the respiration of indoor patients and the air brought in by air conditioning. The main destinations are absorption by people, natural death, and leaving the room with air conditioning exhaust. According to the wearing of masks by people in public places, the personnel protection factor β is introduced, 0≤β≤1, which indicates the proportion of aerosol particles containing pathogens passing through the protective measures. When people do not wear masks, β=1, then the change of the number of aerosol particles containing pathogens in the room is: Among them, V room is the indoor air volume, i.e., the room volume, m 3 ; c(τ) is the average concentration of pathogen-containing aerosols in the indoor air at time τ, number / m 3 ; c(τ) is related not only to time but also to spatial coordinates. Here, c(τ) refers to the average concentration of pathogen-containing aerosol particles at various locations in the room at a certain moment; τ is time, h; is the air volume supplied to the room per unit time, m 3 / h; c s (τ) is the concentration of pathogen-containing aerosol particles in the supply air, number / m 3 ; β is the personnel protection coefficient. Here, it is assumed that all indoor personnel adopt the same hygienic protection measures; n(τ) is the number of indoor infected persons at time τ; is the exhaled air volume of a person, which is equal to the inhaled air volume, m 3 / (h·person); c p (τ) is the concentration of pathogen-containing aerosol particles in the exhaled air of a patient, number / m 3 ; is the air volume discharged from the room per unit time, m 3 / h; is the reduction in the number of pathogen-containing aerosol particles caused by natural death at time τ, number / h; N(τ) is the total number of people in the room at time τ; When the indoor air change rate reaches 5 times, the concentration of pathogen-containing aerosol particles reaches a steady state; since the half-life of the virus is 1.2 h, when the indoor air change rate exceeds 3 times, the reduction in the number of pathogen-containing aerosols due to natural death can be ignored; and the average inspiratory volume of a single person's one-time breathing is 0.5 L, so the exhaust air volume is much larger than the inspiratory volume of indoor personnel; when a disinfection device is installed in the air conditioning system, let the protection coefficient of the air conditioning system be β f , 0 ≤ β f ≤ 1, which represents the ratio of pathogen-containing aerosol passing through the air conditioning system. Therefore, for the concentration of pathogen-containing aerosol in the indoor air of an all-air air conditioning system with a fresh air ratio of α, the steady-state concentration term sub-model is: S2. Probability model of indoor personnel inhaling aerosols containing pathogens: It is assumed that the aerosol particles containing pathogens are dispersed into the indoor air immediately after being exhaled by the patient and are randomly distributed, and the total number of aerosol particles and the number of aerosol particles containing pathogens remain unchanged; since the order of magnitude of the total number of aerosol particles in the indoor air and the total number of aerosol particles discharged by a person in one breathing process is much larger than the order of magnitude of the probability of a single aerosol particle being inhaled, the probability of a person inhaling aerosol particles containing pathogens follows a Poisson distribution: Where P(τ) is the probability of a person inhaling aerosol particles containing pathogens when staying indoors for a continuous period of τ; V1 is the volume of gas inhaled by the indoor person, m 3 ; τ is the continuous stay time of the personnel in the room, h; τ0 is the average time taken by the personnel to breathe once, h; c is the average concentration of pathogen-containing aerosols in the air at various places in the room at time τ, p / m 3 ; S3. Propose the safe duration of indoor aerosol in air-conditioning environment in public places: Define an indoor environment where the probability of a person inhaling pathogen-containing aerosol particles does not exceed 5% as a safe and healthy environment. Then, the maximum continuous stay time of a person indoors should not exceed the aerosol safety duration τ of the indoor environment. safe ; Using the methods of steps S1 and S2, as a measure of the air safety evaluation index in public places, the aerosol safety duration of this indoor environment should satisfy Equation (4): When the air conditioning system provides different fresh air volumes and supply air volumes, the created indoor environment has different indoor environmental aerosol safety durations; S4. Propose an anti-virus control strategy for air conditioning systems based on the safe duration of indoor environmental aerosols: The control parameters of the comfort full air conditioning system include indoor temperature and humidity of the air-conditioned room, indoor CO2 concentration, indoor positive pressure, and during the virus prevention and control period, there is also an additional indoor environmental aerosol safety time of the air-conditioned room; The specific control steps are as follows: S41. Calculation method of fresh air volume in air-conditioned rooms: According to the deviation between the measured value of indoor CO2 concentration and the set value, the fresh air ratio of the room is calculated; S42, disinfection device opening and closing control: When a virus appears locally, the disinfection device in the air-conditioning system is turned on by the air-conditioning system maintenance and management personnel until the local virus is eliminated and then turned off. The value of β f is related to the filtration efficiency of the disinfection device; at other times, the disinfection device is always in the off state, and β f = 1; S43. Calculation method of air supply volume in air-conditioned rooms: Calculate the fresh air ratio α of each room according to the method of step S41, and determine the β f value. The personnel protection factor β is determined according to the mask wearing situation of the personnel in the room. The number of indoor infected persons is the rounded value of the product of the total number of people in the room and the average initial infection rate of 2.2% in Chinese cities. When the product result is less than 1, it is considered that there is 1 indoor infected person; Therefore, combining the above parameters and the method of step S3, calculate the required air supply volume of each room and the total air supply volume of the air conditioning system according to the safe duration of indoor environmental aerosol. S44, CO2 concentration control strategy for air-conditioned rooms: According to the total fresh air volume calculated by the method of step S41 and the total supply air volume calculated by the method of step S43, the fresh air ratio of the air conditioning system is calculated, and the opening of the fresh air valve is adjusted according to the fresh air ratio so that the indoor CO2 concentration reaches the set value requirement, and the deviation cannot exceed the allowable error range; the opening of the return air valve is adjusted so that the sum of the opening of the return air valve and the opening of the fresh air valve is 1; S45. Indoor environment aerosol safety duration control strategy: According to the air supply volume of each room calculated by the method of step S43, the air valve in the terminal variable air volume box is adjusted to make the air supply volume reach the set value requirement; the frequency of the air supply fan is adjusted according to the static pressure of the reference point at the end 1 / 3 of the main air duct, so that the static pressure of the reference point is maintained at its set value, and the deviation cannot exceed the allowable error range; the time magnitude of the variable air volume box adjustment process is greater than the time magnitude of the air supply fan frequency adjustment process; S46, Indoor positive pressure control strategy for air-conditioned rooms: To ensure that the air-conditioned room has a certain positive pressure, the return air fan speed is adjusted by a feedforward control method according to the total air supply volume set value calculated by the method in step S43 and the rated total air volume of the air-conditioning unit; S47, Indoor temperature and humidity control strategy of air-conditioned rooms: Adjust the opening degree of the chilled water valve of the air handling unit according to the indoor temperature and humidity to change the supply air temperature, so that the indoor temperature and humidity reach the set values, and the deviation shall not exceed the allowable error range.

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