Feed-forward refrigerating system for controlling refrigerating capacities of different building units

Abstract

The invention provides a feed-forward refrigerating system for controlling refrigerating capacity of different building units, which comprises an evaporator, a condenser, a compressor, an expansion valve, a water segregator and a water collector, the condenser, the expansion valve, the evaporator and the compressor are sequentially connected to form a refrigerating cycle, water in the water collector enters the water segregator after the evaporator releases heat, and the water in the water collector enters the water segregator after the evaporator releases heat. The water distributor is provided with a plurality of water distribution pipes, the water distribution pipes are connected with heat exchangers of different building units, heat exchange is carried out between the water distribution pipes and air entering the heat exchangers in the heat exchangers to form low-temperature air, then the low-temperature air is conveyed to the building units for refrigeration, and water after heat exchange enters the water collector; the method is used for controlling the amount of water entering different building units. The refrigerating capacity of the refrigerating system is adjusted by adjusting the flow of refrigerating water, the flow of the refrigerating water is controlled by the control valve on the water distribution pipe, the percentage of the output predicted load in the total load of the air conditioning system is calculated according to the predicted load, the percentage of the opening degree of the valve is determined, and the opening degree of the valve is adjusted according to the percentage.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and in particular to a compression refrigeration air supply system. Background Art

[0002] Large buildings, especially public ones, are prone to high energy consumption and low energy efficiency. Especially during the cooling season, due to the uncertainty and volatility of a building's cooling load, refrigeration and air conditioning units often operate in a traditional fixed mode, resulting in significant energy waste.

[0003] The cooling capacity distribution of existing central air conditioners, that is, the cooling capacity in the cooling state, is generally adjusted by a thermostat installed at the end of the air conditioner. However, this adjustment method has the problem of low adjustment accuracy and easy waste of resources.

[0004] Prior art also provides cooling capacity allocation technology. For example, CN104566785A discloses a central air conditioner that uses a cloud server, a mobile communication terminal, an indoor temperature data collector, an outdoor temperature data collector, and a display with a display control receiving module to perform comprehensive adjustment and analysis based on user needs and the user's indoor and outdoor temperature and humidity, thereby maximizing air conditioning resource conservation while meeting user needs. CN114264045A discloses a control module for adjusting central air conditioner operating parameters to achieve optimal energy efficiency based on the results of data module processing and comparison; the monitoring module is used to monitor changes in central air conditioner energy efficiency and a standard model, and to issue an alarm message when the actual energy efficiency changes deviate from the standard model. CN101158495A provides a fully enclosed compressor refrigeration system capable of two-stage cooling capacity regulation. The system comprises a compressor, a condenser, an expansion valve, and an evaporator, which are connected by piping to form a sealed system. The system also includes a hot gas bypass circuit, which is composed of a solenoid valve and a throttling element connected in series. The inlet of the solenoid valve is connected to the high-pressure exhaust pipe of the compressor, and the outlet of the throttling element is connected to the pipeline between the expansion valve and the evaporator. A temperature sensor is provided at the refrigerant outlet of the evaporator. The control signal output terminal of the temperature sensor is connected to the control signal input terminal of the solenoid valve.

[0005] The above-mentioned prior art cooling capacity distribution technology has problems such as complex structure and inaccurate control. Therefore, there is an urgent need for a refrigeration system that can comprehensively adjust the cooling capacity so as to maximize energy saving while meeting user needs. Summary of the Invention

[0006] The object of the present invention is to provide a refrigeration system for comprehensively adjusting the refrigeration capacity so as to achieve energy saving effects to the maximum extent while meeting the needs of users.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A feedforward refrigeration system for controlling the cooling capacity of different building units includes an evaporator, a condenser, a compressor, an expansion valve, a water distributor and a water collector. The condenser, expansion valve, evaporator and compressor are connected in sequence to form a refrigeration cycle. The water in the water collector enters the water distributor after the evaporator releases heat. The water distributor is provided with multiple water distribution pipes. The water distribution pipes are connected to the heat exchangers of different building units. The water exchanges heat with the air entering the heat exchanger in the heat exchanger to form low-temperature air. The low-temperature air is then transported to the building unit for cooling. The water after heat exchange enters the water collector. Valves are provided on the water distribution pipes to control the amount of water entering different building units.

[0009] As an improvement, the valve is connected to the control system data, and the control system automatically controls the opening size of the valve according to the cooling capacity required by the building unit.

[0010] As an improvement, when the cooling capacity required by the building unit increases, the opening of the automatic control valve increases; when the cooling capacity required by the building unit decreases, the opening of the automatic control valve decreases; when the cooling capacity required by the building unit increases, the opening of the automatic control valve increases.

[0011] As an improvement, the return air duct and the fresh air duct are arranged vertically, and a mixing component is provided in the return air duct, and the mixing component is provided upstream of the connection position of the fresh air duct and the return air duct; the mixing component is a blade structure, and the blade structure includes multiple blades, and the extension direction of the gap between adjacent blades is parallel to the direction of the central axis of the fresh air duct; a fresh air mixing device is provided in the fresh air duct, and the fresh air mixing device is a blade structure, which is provided upstream of the connection position of the fresh air duct, and the blade structure is provided with multiple blades, and the extension direction of the flow channel between adjacent blades is parallel to the direction of the central axis of the return air duct.

[0012] As an improvement, the return air flow channels formed by adjacent blades of the mixing component have different spacings. As the distance from the fresh air duct increases, the return air flow channels formed by adjacent blades become smaller and smaller.

[0013] As an improvement, the size of the return air duct spacing can be set by adjusting the size of the blades.

[0014] As an improvement, the farther the same blade is from the fresh air duct, the wider the blade becomes, and the spacing between adjacent blades is reduced by increasing the width.

[0015] As an improvement, the cooling capacity required by the building unit is determined based on a historical cooling load correction model.

[0016] As an improvement, the load model of the historical cooling load calculation model has three main branches: building load branch, heat source load branch and fresh air load branch.

[0017] A method for controlling a refrigeration system comprises the following steps:

[0018] The first step is to collect historical data;

[0019] The second step is to establish a historical cooling load calculation model;

[0020] The third step is to build a training model.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The refrigeration system adjusts the cooling capacity by adjusting the flow of chilled water. The control valve on the water distribution pipe controls the flow of chilled water. The predicted load is calculated based on the percentage of the output predicted load to the total load of the air-conditioning system, and the valve opening percentage is determined to adjust the valve opening accordingly.

[0023] 2. The present invention uses a method based on historical cooling load data to predict cooling capacity. The historical data contains information on cooling loads under different previous operating conditions, such as the impact of different seasons, weather conditions, indoor human activity density and other factors on cooling demand. By integrating these data, the patterns and rules of load changes can be identified, avoiding the problem of traditional prediction methods that rely too much on meteorological variables and time variables. This makes data acquisition more convenient and quick, while weakening the need for physical models and improving the universality and accuracy of load prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the refrigeration system of the present invention.

[0025] Figure 2 It is a schematic diagram of the return air and fresh air mixing structure of the present invention.

[0026] Figure 3 It is a schematic diagram of the principle of the refrigeration capacity prediction module of the refrigeration system of the present invention. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] In this article, unless otherwise specified, “ / ” represents division, and “×” and “*” represent multiplication.

[0029] Figure 1A feedforward refrigeration system for controlling the cooling capacity of different building units is presented. The system includes an evaporator 1, a condenser 2, a compressor 3, an expansion valve 4, a water distributor 5, and a manifold 6. These evaporator 1, condenser 2, compressor 3, and expansion valve 4 are connected in sequence to form a refrigeration cycle. Water from the manifold 6 enters the evaporator 3, exchanges heat with the refrigerant in the evaporator 1, and then releases heat before entering the water distributor 5. The water distributor 5 is equipped with multiple water distribution pipes 7, which connect to heat exchangers 8 in different building units 9. Water from the water distributor 5 flows through the water distribution pipes 7 into the heat exchanger 8, where it exchanges heat with air entering the heat exchanger 8, generating low-temperature air. This low-temperature air is then transported to the building unit 9 for cooling. After heat exchange in the heat exchanger 8, the water enters the manifold, thus forming a water circulation system. Valves are provided on the water distribution pipes 7 to control the amount of water entering different building units 9.

[0030] The present invention controls the refrigeration capacity of different units by arranging valves on the water distribution pipes. The refrigeration capacity is controlled by controlling the amount of cold source water through a single control valve, and the control structure is simple and reliable.

[0031] As an improvement, the valve is connected to a control system, which automatically controls the valve opening according to the cooling capacity required by the building unit. The control system intelligently controls the valve opening, thereby achieving intelligent control.

[0032] As an improvement, when the cooling capacity required by a building unit increases, the automatic control valve opening increases; when the cooling capacity required by a building unit decreases, the automatic control valve opening decreases; and when the cooling capacity required by a building unit increases, the automatic control valve opening increases. This intelligent control achieves accurate regulation of cooling capacity.

[0033] As an improvement, the air entering the heat exchanger consists of 50-80% return air and 20-50% fresh air. The return air and fresh air are mixed before entering the heat exchanger. Because the return air is cooler than the outdoor fresh air, by returning the return air from the building units to the heat exchanger, the cooling capacity of the return air can be fully utilized, saving energy.

[0034] Figure 2 The schematic diagram of the structure of the mixing duct for return air and fresh air is shown. Figure 2 As shown, the return air duct 10 is arranged perpendicular to the fresh air duct 11, and a mixing component 12 is provided in the return air duct 10, and the mixing component 12 is provided upstream of the connection position between the fresh air duct and the return air duct; the mixing component 12 is a blade structure, and the blade structure includes a plurality of blades, and the extension direction of the gap between adjacent blades is arranged parallel to the central axis direction of the fresh air duct.

[0035] A fresh air mixing device 13 is provided within the fresh air duct 11. This device is a vane structure, located upstream of the connection point of the fresh air duct 11. The vane structure comprises multiple vanes, with the flow paths between adjacent vanes extending parallel to the central axis of the return air duct. This arrangement ensures that the gaps between the return air duct and the fresh air duct distribution components are parallel to each other, minimizing impact and noise during fluid mixing.

[0036] As an improvement, the return air layer where the flow channel of the return air equalizing component is located is staggered with the fresh air layer where the flow channel of the fresh air distribution component is located. By staggering the flow channels of the two, during mixing, the fresh air layer flowing out of the fresh air flow channel can enter the space between the two return air layers of the staggered adjacent return air flow channel layers. At the same time, the return air flowing out of the return air flow channel layer can enter the space between the adjacent fresh air layers. This makes the return air layer and the fresh air layer staggered and spaced apart, making the distribution more uniform, and also reducing noise and impact.

[0037] The return air flow channels formed by adjacent blades of the mixing component 12 have different spacings. As the distance from the fresh air duct increases, the return air flow channels formed by adjacent blades become smaller and smaller.

[0038] Near the fresh air outlet, the fresh air flow is the largest, and the mixing of fresh air and return air is the best at this time, which leads to uneven mixing overall. As the distance from the outlet increases, the fresh air decreases and the mixing becomes worse, resulting in poor overall mixing effect. The present invention improves the blade spacing so that the return air flow decreases along the direction in which the fresh air enters the return air duct, and the mixing is balanced throughout the entire area, thereby improving overall mixing uniformity.

[0039] As an improvement, the size of the return air duct spacing can be set by adjusting the size of the blades. For example, the farther the same blade is from the fresh air duct, the wider the blade is, and the spacing between adjacent blades is reduced by increasing the width.

[0040] Based on the existing air conditioner, the present invention creatively proposes a mixed adjustment system for fresh air and return air, which includes two upstream and downstream split adjustment devices to achieve dual control and dual flow equalization, so that the return air and fresh air ratio effect is obvious and has high economic benefits.

[0041] Preferably, as the distance from the fresh air duct increases, the return air duct formed by adjacent blades becomes smaller and smaller. By changing the spacing amplitude, the balancing effect can be better improved and the overall mixing can be more uniform.

[0042] Preferably, Figure 2As shown, the return air duct is equipped with a return air flow equalizer 14, located downstream of the connection between the fresh air duct and the return air duct. The flow equalizer 14 has a multi-blade structure. As an improvement, the flow channel spacing between adjacent blades increases as they are farther from the fresh air duct. This arrangement allows the mixed air to flow as far away from the fresh air duct as possible, thereby improving the previously concentrated mixed air near the fresh air duct and ensuring that the mixed air is evenly distributed throughout the return air duct.

[0043] As an improvement, the farther away from the fresh air duct, the greater the distance between the fuel flow channels of the adjacent blades of the return air flow equalization device 14 is, the larger the range is. The above arrangement can further evenly distribute the mixed air throughout the return air duct.

[0044] As an improvement, the flow passage of the flow equalizing device 14 and the flow passage of the mixing component 12 are arranged perpendicular to each other. Since the two sets of regulating devices are perpendicular to each other, the flow can be diffused in all four directions, horizontally and vertically, and the degree of uniformity is higher.

[0045] The present invention includes two upstream and downstream devices to achieve dual control and dual flow balancing, resulting in a significant effect on the equalization of the return and fresh air ratios. The subsequent equalization device also ensures uniform distribution throughout the pipeline. The combination of these two devices can achieve flow control, uniform distribution ratios, and uniform fuel distribution throughout the pipeline.

[0046] Preferably, multiple mixing devices 14 are provided, and the gaps between adjacent blades in the mixing device become smaller and smaller along the flow direction of the fluid in the return air duct. By varying the amplitude, on the one hand, the flow distribution can be further uniformed while maintaining low flow resistance.

[0047] The present application also discloses a refrigeration system for regulating cooling capacity based on cooling load prediction of a historical cooling load correction model.

[0048] Existing cooling load prediction methods still have some shortcomings. When calculating a building's cooling load, they primarily consider fresh air cooling load, occupancy cooling load, building envelope cooling load, and internal heat source cooling load. These cooling loads are primarily influenced by building envelope physical parameters, outdoor temperature and humidity, and indoor heat sources. When calculating a building's real-time cooling load, since building physical parameters do not change over time, we can only consider changes in outdoor temperature and humidity and indoor heat sources. For office buildings, the primary indoor heat source—occupancy—exhibits a certain regularity: the number of occupants, their length of stay, and their activity types all cycle on a weekly basis. Furthermore, outdoor temperature and humidity also exhibit a certain regularity, cycling continuously on an annual basis. Given the cyclical nature of these important factors, historical cooling loads are highly valuable for predicting cooling loads.

[0049] One of the objectives of the present invention is to provide a building cooling load prediction method based on a historical cooling load correction model.

[0050] The first step is to collect historical data. Air conditioning periods are defined and relevant information collected during these periods, including historical personnel and weather data, as well as building characteristics. The personnel module primarily collects data on historical personnel numbers and activity types. The building module primarily collects data on building structure, interior and exterior wall areas, material properties, building location, and door and window leakage. The meteorological module primarily collects data on outdoor temperature and humidity, solar radiation, and wind direction.

[0051] The second step is to establish a historical cooling load calculation model. The load model has three main branches: building load branch, heat source load branch, and fresh air load branch.

[0052] The main calculation formulas for the building cooling load branch are

[0053] Q=KF·(t wq -t n )k a k ρ

[0054] Where: Q is the hourly cooling load of the exterior wall or roof, W;

[0055] F——area of ​​exterior wall or roof, m 2 ;

[0056] K——heat transfer coefficient of exterior wall or roof, W / (m 2 ℃)

[0057] t wq ——Hourly cooling load calculation temperature of the exterior wall or roof, °C;

[0058] t n ——Calculated indoor temperature, °C;

[0059] k a ——Correction value of heat release coefficient of external surface;

[0060] k ρ ——Correction for the absorption coefficient.

[0061] Extract the interior and exterior wall areas from the building characteristics module, determine the exterior wall or roof heat transfer coefficient based on the building's physical parameters, and combine the outdoor temperature data from the meteorological conditions module as the hourly cooling load calculation temperature for the exterior wall or roof. The indoor calculation temperature is a constant, and the historical value of this part of the cooling load can be accurately output.

[0062]

[0063] Where: ——Hourly cooling load of unsteady-state heat transfer of exterior windows, W

[0064] K——heat transfer coefficient of exterior window, W / (m 2 K);

[0065] F——heat transfer area of ​​external window, m 2 ;

[0066] t wlc ——Hourly cooling load calculation temperature of external windows, °C;

[0067] t n ——Design temperature of air-conditioned area in summer, ℃.

[0068] C a ——effective area coefficient;

[0069] C s - shading coefficient of window glass;

[0070] C i - shading coefficient of sun shading facilities inside windows;

[0071] C LQ — cooling load coefficient of window glass;

[0072] D jmax ——The maximum value of solar heat gain factor at each latitude in summer, W / m 2 .

[0073] The exterior window area is determined by extracting data from the building characteristics module and combining it with the building physical parameters from the data modalities in the building characteristics module to determine the exterior window heat transfer coefficient. Finally, the outdoor temperature data from the meteorological conditions module is used as the temperature for calculating the exterior window hourly cooling load. The air-conditioning zone design temperature is set as a constant value to calculate the exterior window hourly cooling load. The exterior window hourly cooling load is summed with the exterior wall cooling load to output the building's partial cooling load.

[0074] The main calculation formulas for the heat source load branch are:

[0075] Q r =Q S ·C CLrt +Q q

[0076] Q s =n·Φ·Q rt

[0077] Q q =n·Φ·q

[0078] Q r ——Cooling load caused by human body heat dissipation, W;

[0079] Q S ·C CLrt ——Sensible cooling load, W;

[0080] C CLrt ——Cooling load coefficient of sensible heat dissipation of human body;

[0081] Q q ——latent cooling load, W;

[0082] Φ——clustering coefficient, taken as 0.93;

[0083] Q rt ——Human body heat dissipation, W;

[0084] n——number of people in the air-conditioned room;

[0085] q——latent heat emitted by each person, W.

[0086] The sensible heat dissipation cooling load coefficient and cluster coefficient in the variable input parameters are determined according to national standards, while the number of people in the air-conditioned room and the latent heat dissipation per person are determined by the personnel history module. The number of people and the type of personnel activities are determined by querying the air-conditioning design specifications to determine the latent heat dissipation of people with different activity types. The total personnel load is finally calculated through the heat source load branch.

[0087] The main calculation formulas for the fresh air load branch are:

[0088]

[0089] ρ w ——Calculate the density of outdoor air conditioner at dry bulb temperature in summer;

[0090] L——fresh air volume, m 3 / h;

[0091] t w ——Calculated dry bulb temperature of outdoor air conditioning, °C;

[0092] t n ——Calculated indoor temperature, °C;

[0093] The fresh air density and outdoor air dry-bulb temperature are obtained from meteorological modes. In order to achieve a higher standard of indoor air quality, the fresh air volume is generally taken as 20-50% of the total air supply volume, preferably more than 40%. The indoor calculation temperature is selected according to the national standard requirements, and the fresh air load is finally obtained.

[0094] Add all branch loads to determine the total building load, and create a database of cooling loads and corresponding hours. To ensure the reliability of the load forecast, the database should include at least five years of historical data. Since the annual change pattern is roughly the same, historical data should be coded and entered in annual units.

[0095] The third step is to establish a training model. First, the cooling load time variable history information and hours of the feature extraction network are input into the neural network system as samples. The predicted load output value a is calculated according to the following formula

[0096]

[0097] Among them, x i is the input variable, the input variable is the historical real-time cooling load, w0 is the bias term, w i is the weight assigned to each input variable, and the weight w is randomly initialized i and bias b i The output variable is the predicted future cooling load. 5 hidden neurons are set and the number of iterations is 60,000. The sample data is input into the network. After calculation, it is input to the hidden layer. Function f is a nonlinear activation function applied on the sum of products. It is used to introduce nonlinearity in the sum of the input and their corresponding weight values. Stronger nonlinear capabilities can be achieved by using multiple hidden layers. Set f to sigmoid function. After activation, the final output prediction value is obtained by weight distribution and bias addition. The mean square error (MSE) between the output value and the sample value is calculated. y i1 is the predicted load obtained after calculation, and y1 is the cooling load in the sample. The predicted load and sample load are substituted into the above formula to calculate the error. Multiple errors are added together, and the minimum error is found according to the negative gradient direction through continuous iteration to determine the final weight and bias of the model. The prediction model is repeatedly iteratively trained through the training set data to finally obtain the optimal model structure and parameter combination, thereby obtaining the final cooling load prediction result.

[0098] The refrigeration system includes a cooling water cycle and a chilled water cycle. The chilled water cycle and the cooling water cycle together form a water cycle. Two screw chillers are installed in the water cycle, one for use and one for backup, and two chilled water pumps, two cooling water pumps and two cooling towers are installed accordingly. After being cooled by the cooling water in the chiller, the chilled water enters the manifold, enters the combined air conditioning unit to exchange heat with the air, and after being heated, it is pressurized by the chilled water pump and returned to the chiller, completing the chilled water cycle. After the cooling water obtains the heat of the chilled water in the chiller, it enters the cooling tower, is cooled, and is pressurized by the cooling water pump and then enters the chiller, completing the cooling water cycle. The air cycle selects a full air system. The chilled water is transported to the corresponding floor of the building through the water system and then enters the air conditioning unit on this floor for heat exchange. After being collected and mixed, it is exchanged with chilled water for cooling. The air supply state point is determined using a single return air dew point air supply method. After reaching the air supply state, it is transported to the relevant rooms through the air supply pipe and diffuser.

[0099] This refrigeration system adjusts cooling capacity by regulating the chilled water outlet flow rate, which is controlled via a valve on a water distribution pipe. The valve is controlled in consecutive time intervals of equal length. Based on the predicted load, the percentage of the output predicted load to the total load of the air conditioning system is calculated and used to adjust the valve opening. A more advanced approach is to determine the valve opening percentage over a number of time intervals, each corresponding to the predicted output load. The adjustment threshold is between 60% and 100%, meaning the chilled water flow control valve opening is between a minimum of 60% and a maximum of 100%. Exemplarily, the preset first range can be 60-80%, and the preset first adjustment threshold is 80% of the maximum opening of the regulating valve. If the predicted load rate is lower than 60%, the regulating valve is adjusted within the preset first range; when the predicted load rate is greater than 60%, the regulating valve should be adjusted between the second preset threshold values, and the second preset threshold value range is 80-100%; the chilled water outlet temperature is directly controlled by the chiller, and the chiller should include a temperature sensor and an electronic valve. The chilled water outlet temperature is controlled in continuous time intervals of the same length. The load percentage is determined by the predicted load, and the most suitable outlet temperature is matched. The electronic valve is opened after the temperature monitored by the temperature sensor meets the adjustment requirements.

[0100] Although the present invention has been disclosed above with reference to preferred embodiments, the present invention is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope defined by the claims.

Claims

1. A feedforward refrigeration system for controlling the cooling capacity of different building units, comprising an evaporator, a condenser, a compressor, an expansion valve, a water distributor and a water collector. The condenser, expansion valve, evaporator and compressor are connected in sequence to form a refrigeration cycle. Water in the water collector enters the water distributor after releasing heat in the evaporator. The water distributor is provided with multiple water distribution pipes, which are connected to heat exchangers of different building units. The water exchanges heat with the air entering the heat exchanger in the heat exchanger to form low-temperature air. The low-temperature air is then transported to the building units for cooling. The water after heat exchange enters the water collector. Valves are provided on the water distribution pipes to control the amount of water entering different building units.

2. The refrigeration system according to claim 1, wherein: The valve is connected to the control system data, and the control system automatically controls the opening size of the valve according to the cooling capacity required by the building unit.

3. The refrigeration system according to claim 2, wherein: When the cooling capacity required by the building unit increases, the opening of the automatic control valve increases; when the cooling capacity required by the building unit decreases, the opening of the automatic control valve decreases; when the cooling capacity required by the building unit increases, the opening of the automatic control valve increases.

4. The refrigeration system according to claim 1, wherein: The return air duct and the fresh air duct are arranged vertically, and a mixing component is provided in the return air duct, and the mixing component is provided upstream of the connection position of the fresh air duct and the return air duct; the mixing component is a blade structure, and the blade structure includes multiple blades, and the extension direction of the gap between adjacent blades is parallel to the central axis direction of the fresh air duct; a fresh air mixing device is provided in the fresh air duct, and the fresh air mixing device is a blade structure, which is provided upstream of the connection position of the fresh air duct, and the blade structure is provided with multiple blades, and the extension direction of the flow channel between adjacent blades is parallel to the central axis direction of the return air duct.

5. The refrigeration system according to claim 4, wherein: The return air flow channels formed by adjacent blades of the mixing component have different spacings. As the distance from the fresh air duct increases, the return air flow channels formed by adjacent blades become smaller and smaller.

6. The refrigeration system according to claim 5, wherein: The size of the return air duct spacing can be set by adjusting the size of the blades.

7. The refrigeration system according to claim 6, wherein: The farther the same blade is from the fresh air duct, the wider the blade becomes, and the distance between adjacent blades is reduced by increasing the width.

8. The refrigeration system according to claim 2, wherein: The cooling capacity required by the building units is determined based on a historical cooling load correction model.

9. The refrigeration system according to claim 8, wherein: The load model of the historical cooling load calculation model has three main branches: building load branch, heat source load branch and fresh air load branch.

10. A method for controlling a refrigeration system according to any one of claims 1 to 9, comprising the following steps: The first step is to collect historical data; The second step is to establish a historical cooling load calculation model; The third step is to build a training model.

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