Air conditioning system

Abstract

The utility model provides an air conditioning system, which comprises a fresh air conditioning processing unit, a fresh air conditioning processing unit, a fresh air conditioning processing unit, a fresh air conditioning processing unit, a fresh air conditioning processing unit, a fresh air conditioning processing unit and a fresh air conditioning processing unit, and the fresh air conditioning processing unit comprises a first box body, a first surface air cooler and a first air feeder, the under-floor air supply air conditioning unit comprises a second box body, a second surface air cooler and a second air supply machine, an air inlet, a primary air return opening, a secondary air return opening and an air supply opening are formed in the second box body, the air inlet is connected with the first box body through a fresh air pipeline, the primary air return opening is communicated into a room through a primary air return pipe, and the secondary air return opening is communicated into the room through a secondary air return pipe; the second surface air cooler and the second air feeder are located in the second box body and arranged between the primary air return opening and the air supply opening, and the secondary air return opening and the air inlet are located between the second surface air cooler and the second air feeder. The air conditioner is low in energy consumption, independent control over the temperature and the humidity can be achieved, the indoor temperature can not be too low under the condition that no extra energy is consumed, and the requirement for comfort of the air supply temperature is met.

Description

Technical Field

[0001] The utility model relates to the technical field of air conditioning, in particular to an air conditioning system. Background Art

[0002] In the field of construction, the energy consumption of air-conditioning systems accounts for a large proportion of the total energy consumption of the entire building. How to efficiently utilize high-grade energy and low-grade energy, realize the classified and graded use of energy, and reduce the energy consumption of air-conditioning systems is one of the important methods to reduce carbon emissions in buildings.

[0003] At present, most air-conditioning systems adopt the air flow organization of top air supply and upward return. The air supply temperature requirement is low. The air conditioner needs to bear the entire load from the low-level human activity area to the high-level non-human activity area in the indoor space. Therefore, the required air-conditioning load is large and the energy consumption is high.

[0004] At the same time, traditional air conditioning systems generally use a single air conditioning unit to cool and dehumidify the air, but this also makes it impossible to independently control the indoor temperature and humidity. When the temperature meets the design conditions, the humidity cannot meet the requirements, and when the humidity meets the design conditions, the temperature cannot meet the requirements. For occasions with high requirements for temperature and humidity, other means such as reheating can only be used to ensure that when the humidity reaches the requirement, the temperature can also meet the requirements and not be too low, but this increases unnecessary energy consumption.

[0005] Therefore, in order to overcome the shortcomings of the full air conditioning system, which has a heavy load due to the burden on the entire height of the indoor space, and the low supply air temperature that requires reheating and other measures to meet the comfort requirements of the supply air temperature, and the inability to control temperature and humidity independently, it is urgent to design an air conditioning system that can reduce the indoor air conditioning load and can independently control temperature and humidity, so as to achieve decoupling of temperature and humidity control and reduce its energy consumption. Utility Model Content

[0006] The purpose of the utility model is to provide an air-conditioning system with low overall energy consumption, which can realize independent control of temperature and humidity, and can also prevent the indoor temperature from being too low without consuming additional energy, thereby meeting the comfort requirements of the air supply temperature.

[0007] In order to achieve the above object, the utility model provides an air conditioning system, which includes:

[0008] A fresh air air conditioning processing unit, comprising a first box, a first surface cooler and a first air blower, wherein the first box is provided with a fresh air inlet and a fresh air outlet, the first surface cooler and the first air blower are both located in the first box and between the fresh air inlet and the fresh air outlet, the first surface cooler is close to the fresh air inlet, and the first air blower is close to the fresh air outlet;

[0009] An underfloor air supply air conditioning unit, comprising a second box, a second surface cooler and a second air supply fan, the second box is provided with an air inlet, a primary return air inlet, a secondary return air inlet and an air supply inlet, the air inlet is connected to the fresh air outlet through a fresh air duct, the primary return air inlet leads to the room through the primary return air duct, the secondary return air inlet leads to the room through the secondary return air duct, and the air supply inlet leads to the room through the air supply duct; the second surface cooler and the second air supply fan are located in the second box, and are sequentially arranged between the primary return air inlet and the air supply inlet, the secondary return air inlet and the air inlet are both located between the second surface cooler and the second air supply fan;

[0010] The outlet of the air supply duct is located below the floor, and the inlets of the primary air return duct and the secondary air return duct are respectively close to the indoor ceiling.

[0011] Optionally, a primary return air regulating valve is provided at the primary return air outlet, and a secondary return air regulating valve is provided at the secondary return air outlet.

[0012] Optionally, the air conditioning system includes a supply air temperature sensor and a controller, the supply air temperature sensor is arranged on the supply air duct, the supply air temperature sensor is communicatively connected to the controller, and the controller is respectively connected to the primary return air regulating valve and the secondary return air regulating valve.

[0013] Optionally, the first cooler is connected to a first supply and return water pipeline, and the first cooler is connected to the air-conditioning water system through the first supply and return water pipeline; the second cooler is connected to a second supply and return water pipeline, and the second cooler is connected to the air-conditioning water system through the second supply and return water pipeline.

[0014] Optionally, the number of the second supply and return water pipelines is two sets, one set of the second supply and return water pipelines is used to connect to the air-conditioning water system of the low-temperature cold source, and the other set of the second supply and return water pipelines is used to connect to the air-conditioning water system of the high-temperature cold source; the first supply and return water pipelines are used to connect to the air-conditioning water system of the low-temperature cold source; the water temperature of the air-conditioning water system of the high-temperature cold source is higher than the water temperature of the air-conditioning water system of the low-temperature cold source.

[0015] Optionally, the fresh air air conditioning processing unit includes a fresh air filter unit located in the first box, and the fresh air filter unit is located between the fresh air inlet and the first surface cooler; the underfloor air supply air conditioning unit includes a return air filter unit located in the second box, and the return air filter unit is located between the primary return air outlet and the second surface cooler.

[0016] Optionally, a fresh air regulating valve is provided at the air inlet of the second box.

[0017] Optionally, the air conditioning system includes a controller and a carbon dioxide sensor arranged indoors, the carbon dioxide sensor is communicatively connected to the controller, and the controller is connected to the fresh air regulating valve.

[0018] Optionally, the air-conditioning system includes a controller, a return air temperature sensor and a humidity sensor, the humidity sensor is arranged indoors, the return air temperature sensor is arranged on the primary return air duct and / or the secondary return air duct, the return air temperature sensor and the humidity sensor are respectively communicated with the controller, and the controller is respectively connected to the first surface cooler and the second surface cooler.

[0019] Optionally, the underfloor air-supply air conditioning unit includes a silencer unit located in the second box, and the silencer unit is arranged between the second air blower and the air outlet.

[0020] As configured above, the utility model adopts a combination of two air conditioning units, namely, a fresh air air conditioning processing unit and an underfloor air supply air conditioning unit, to adjust the indoor temperature and humidity, wherein the fresh air air conditioning processing unit is mainly responsible for adjusting the indoor humidity, and the underfloor air supply air conditioning unit is mainly responsible for adjusting the indoor temperature. The water flow of the first surface cooler of the fresh air air conditioning processing unit and the water flow of the second surface cooler of the underfloor air supply air conditioning unit can be independently controlled, that is, the heat exchange of the first surface cooler and the heat exchange of the second surface cooler can be independently controlled, thereby decoupling the temperature control and the humidity control, and realizing independent control of the temperature and humidity. The indoor air enters the underfloor air supply air conditioning unit through the primary return air duct and the secondary return air duct. The air entering from the primary return air duct needs to flow through the second surface cooler, while the air entering from the secondary return air duct does not need to flow through the second surface cooler. The air cooled by the second surface cooler is mixed with the air entering the second box from the secondary return air port and the air inlet, and then sent into the air supply duct by the second air supply fan. Since the air entering the second box from the secondary return air port is not cooled, the setting of the secondary return air duct can increase the final supply air temperature. It can be used in occasions where higher indoor temperature requirements are required to meet the comfort requirements of the supply air temperature without requiring additional energy consumption. The utility model realizes independent control of temperature and humidity, and can prevent the indoor temperature from being too low without consuming additional energy, thereby meeting the comfort requirement of supply air temperature. At the same time, the outlet of the supply air duct of the utility model is located below the floor, and the inlets of the primary return air duct and the secondary return air duct are close to the indoor top, that is, the supply air flow is organized as downward delivery and upward return. The air in the low-zone personnel activity area will not return to the low zone again after rising, but will form a heat plume with the convective heat source above the high zone (such as light source, etc.) and be discharged together, without constituting a cooling load, thereby greatly reducing the overall energy consumption of the air-conditioning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Those skilled in the art should understand that the drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0022] Figure 1 A schematic diagram of an air conditioning system according to an embodiment of the present utility model;

[0023] Figure 2 It is a schematic diagram of the connection between the first surface cooler of the air-conditioning system of one embodiment of the utility model and the air-conditioning water system of the low-temperature cooling source;

[0024] Figure 3 It is a schematic diagram of the connection between the second surface cooler of the air-conditioning system of one embodiment of the utility model and the air-conditioning water system of the low-temperature cooling source;

[0025] Figure 4 It is a schematic diagram of the connection between the second surface cooler of the air-conditioning system and the air-conditioning water system of the high-temperature cold source according to one embodiment of the utility model.

[0026] The reference numerals are as follows:

[0027] 1-Fresh air conditioning processing unit; 10-First box; 11-First air supply fan; 12-Fresh air outlet; 13-First surface cooler; 14-Fresh air filter unit; 15-Fresh air inlet; 2-Underfloor air supply air conditioning unit; 20-Second box; 201-Air inlet; 202-Primary return air outlet; 203-Secondary return air outlet; 204-Air supply outlet; 21-Second air supply fan; 22-Fresh air regulating valve; 23-Secondary return air regulating valve; 24-Second surface cooler; 25-Return air filter unit; 26-Primary return air regulating valve; 27-Silencer unit; 28-First regulating valve; 29-Second regulating valve; 3-Fresh air duct; 4-Primary return air duct; 5-Secondary return air duct; 6-Supply air duct. DETAILED DESCRIPTION

[0028] In this document, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", "front", "back", "top", "bottom", etc. are used to indicate directions or positional relationships based on the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction and operation. Therefore, they cannot be understood as limiting the present invention.

[0029] The following will describe the specific implementation of the utility model in more detail with reference to the schematic diagram. The advantages and features of the utility model will become clearer according to the following description. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model.

[0030] The preferred embodiments of the present utility model are given below in conjunction with the accompanying drawings and described in detail.

[0031] Figure 1 This is a schematic diagram of an air conditioning system according to an embodiment of the present invention. Figure 1 The embodiment of the utility model provides an air conditioning system, including a fresh air air conditioning processing unit 1, an underfloor air supply air conditioning unit 2 and a controller. The fresh air air conditioning processing unit 1 includes a first box 10, a first surface cooler 13 and a first air supply fan 11. The first box 10 is provided with a fresh air inlet 15 and a fresh air outlet 12. Outdoor fresh air enters the first box 10 through the fresh air inlet 15. The first surface cooler 13 and the first air supply fan 11 are both located in the first box 10 and between the fresh air inlet and the fresh air outlet. The first surface cooler 13 is close to the fresh air inlet, and the first air supply fan 11 is close to the fresh air outlet.

[0032] The underfloor air supply air conditioning unit 2 includes a second box 20, a second surface cooler 24 and a second air supply fan 21. The second box 20 is provided with an air inlet 201, a primary return air inlet 202, a secondary return air inlet 203 and an air supply port 204. In this embodiment, a primary return air regulating valve 26 is provided at the primary return air inlet 202 to adjust the opening and closing degree of the primary return air inlet 202, and a secondary return air regulating valve 23 is provided at the secondary return air inlet 203 to adjust the opening and closing degree of the secondary return air inlet 203. The air inlet 201 is connected to the fresh air outlet through the fresh air duct 3. In this embodiment, a fresh air regulating valve 22 is provided at the air inlet 201 of the second box 20. It can be understood that the greater the opening and closing degree of the fresh air regulating valve 22, the more fresh air enters the second box 20. Furthermore, the air-conditioning system includes a carbon dioxide sensor installed indoors, and the controller adjusts the opening degree of the fresh air regulating valve 22 according to the data fed back by the carbon dioxide sensor. When the carbon dioxide concentration detected by the carbon dioxide sensor is high, the opening degree of the fresh air regulating valve 22 is increased, and vice versa.

[0033] The primary return air port 202 leads to the room through the primary return air duct 4, the secondary return air port 203 leads to the room through the secondary return air duct 5, and the air supply port 204 leads to the room through the air supply duct 6; the second surface cooler 24 and the second air supply fan 21 are located in the second box 20, and are sequentially arranged between the primary return air port 202 and the air supply port 204, the secondary return air port 203 and the air inlet 201 are both located between the second surface cooler 24 and the second air supply fan 21, so that the air entering the second box 20 from the secondary return air port 203 does not need to flow through the second surface cooler 24;

[0034] The outlet of the air supply duct 6 is located below the floor. Specifically, in this embodiment, the outlet of the air supply duct 6 is located in the floor cavity. The inlets of the primary return duct 4 and the secondary return duct 5 are both close to the top of the room. Therefore, the air supply airflow in this embodiment is organized as downward delivery and upward return. The air in the low-level personnel activity area will not return to the low-level area after rising, but will form a heat plume with the convective heat source (such as a light source, etc.) above the high-level area and be discharged together, which does not constitute a cooling load, greatly reducing the overall energy consumption of the air conditioning system.

[0035] Furthermore, the air conditioning system includes a supply air temperature sensor and a controller. The supply air temperature sensor is arranged on the supply air pipe 6. The controller adjusts the opening and closing degrees of the primary return air regulating valve 26 and the secondary return air regulating valve 23 according to the data fed back by the supply air temperature sensor, thereby controlling the temperature of the air delivered to the room. For example, in order to meet the requirements of air supply comfort, the supply air temperature is usually controlled at about 18°C. When the temperature detected by the supply air temperature sensor is higher than 18°C, the controller controls the opening and closing degree of the secondary return air regulating valve 23 to decrease and the opening and closing degree of the primary return air regulating valve 26 to increase, so as to reduce the unrefrigerated air and increase the air flowing through the second surface cooler 24, thereby achieving the purpose of reducing the supply air temperature; when the temperature detected by the supply air temperature sensor is lower than 18°C, the controller controls the opening and closing degree of the secondary return air regulating valve 23 to increase and the opening and closing degree of the primary return air regulating valve 26 to decrease, so as to increase the unrefrigerated air and reduce the air flowing through the second surface cooler 24, thereby achieving the purpose of increasing the supply air temperature.

[0036] The first surface cooler 13 is connected to a first supply and return water pipeline, and the first surface cooler 13 is connected to the air-conditioning water system through the first supply and return water pipeline; the second surface cooler 24 is connected to a second supply and return water pipeline, and the second surface cooler 24 is connected to the air-conditioning water system through the second supply and return water pipeline. Specifically in the present embodiment, the number of the second supply and return water pipelines is two sets, one set of the second supply and return water pipelines is used to connect to the air-conditioning water system of the low-temperature cold source, and the other set of the second supply and return water pipelines is used to connect to the air-conditioning water system of the high-temperature cold source; the number of the first supply and return water pipelines can be one set, which is used to connect to the air-conditioning water system of the low-temperature cold source; it can be understood that the water temperature of the air-conditioning water system of the high-temperature cold source is higher than the water temperature of the air-conditioning water system of the low-temperature cold source. For example, the supply and return water temperature of the air-conditioning water system of the high-temperature cold source is usually 12 / 17°C, and the supply and return water temperature of the air-conditioning water system of the low-temperature cold source is usually 7 / 12°C. This embodiment has two working conditions, which can be referred to Figure 2 , Figure 3 and Figure 4 ,in, Figure 2 and Figure 3 In the first working condition, the first surface cooler 13 and the second surface cooler 24 are both connected to the air conditioning water system of the same low-temperature cooling source, the supply and return water temperatures are about 7 / 12°C, and the temperature difference between the supply and return water temperatures can be between 5°C and 8°C; Figure 2 and Figure 4 In the second working condition, the first cooler 13 is connected to the air conditioning water system of the low-temperature cooling source, and the supply and return water temperature is about 7 / 12°C. The second cooler 24 is connected to the air conditioning water system of the high-temperature cooling source, and the supply and return water temperature is about 12 / 17°C. The temperature can be adjusted within a certain range according to the indoor temperature. In practical applications, the operating energy consumption of using a high-temperature cooling source is about 10% less than that of using a low-temperature cooling source, which is more energy-saving. Furthermore, a first regulating valve 28 is provided on the water supply pipeline of the first cooler 13 for regulating the water flow and heat exchange amount entering the first cooler 13, and a second regulating valve 29 is provided on the water supply pipeline of the second cooler 24 for regulating the water flow and heat exchange amount entering the second cooler 24.

[0037] Generally speaking, the air conditioning system also includes a return air temperature sensor and a humidity sensor. The humidity sensor is arranged indoors to detect the indoor humidity. The controller adjusts the water flow of the first cooler 13 according to the data fed back by the humidity sensor. The implementation method is that the controller adjusts the opening and closing degree of the first regulating valve 28. It can be understood that the greater the opening and closing degree of the first regulating valve 28, the greater the water flow and heat exchange capacity of the first cooler 13. The return air temperature sensor is arranged on the primary return air duct 4 and / or the secondary return air duct 5, that is, the return air temperature sensor can be arranged on one of the primary return air duct 4 and the secondary return air duct 5, or the return air temperature sensor is arranged on both the primary return air duct 4 and the secondary return air duct 5. In some embodiments, the primary return air duct 4 and the secondary return air duct 5 extend from the second box 20 and then merge into a main return air duct. At this time, the return air temperature sensor can be arranged on the main return air duct. The controller adjusts the water flow of the second surface cooler 24 according to the data fed back by the return air temperature sensor. The implementation method is that the controller adjusts the opening and closing degree of the second regulating valve 29. It can be understood that the greater the opening and closing degree of the second regulating valve 29, the greater the water flow and heat exchange capacity of the second surface cooler 24.

[0038] As configured above, the utility model adopts a combination of two air conditioning units, namely, a fresh air air conditioning processing unit 1 and an underfloor air supply air conditioning unit 2, to adjust the indoor temperature and humidity, wherein the fresh air air conditioning processing unit 1 is mainly responsible for adjusting the indoor humidity, and the underfloor air supply air conditioning unit 2 is mainly responsible for adjusting the indoor temperature. The water flow of the first surface cooler 13 of the fresh air air conditioning processing unit 1 and the water flow of the second surface cooler 24 of the underfloor air supply air conditioning unit 2 can be independently controlled, that is, the heat exchange of the first surface cooler 13 and the heat exchange of the second surface cooler 24 can be independently controlled, thereby decoupling the temperature control and the humidity control, and realizing independent control of the temperature and the humidity. The indoor air enters the underfloor air supply air conditioning unit 2 through the primary return air duct 4 and the secondary return air duct 5. The air entering from the primary return air duct 4 needs to flow through the second surface cooler 24, while the air entering from the secondary return air duct 5 does not need to flow through the second surface cooler 24. The air cooled by the second surface cooler 24 is mixed with the air entering the second box 20 from the secondary return air port 203 and the air inlet 201, and then sent into the air supply duct 6 by the second air supply fan 21. Since the air entering the second box 20 from the secondary return air port 203 is not cooled, the setting of the secondary return air duct 5 can increase the final supply air temperature, which can be used in occasions with higher indoor temperature requirements to meet the comfort requirements of the supply air temperature without requiring additional energy consumption. The utility model realizes independent control of temperature and humidity and can prevent the indoor temperature from being too low without consuming additional energy, thereby meeting the comfort requirement of the supply air temperature. At the same time, the outlet of the supply air duct 6 of the utility model is located below the floor, and the inlets of the primary return air duct 4 and the secondary return air duct 5 are close to the indoor top, that is, the supply air flow is organized as downward delivery and upward return, which greatly reduces the overall energy consumption of the air-conditioning system.

[0039] Preferably, the fresh air air conditioning processing unit 1 includes a fresh air filter unit 14 located in the first box body 10, which is used to filter the air, and the fresh air filter unit 14 is located between the fresh air inlet and the first surface cooler 13; the underfloor air supply air conditioning unit 2 includes a return air filter unit 25 located in the second box body 20, which is used to filter the air, and the return air filter unit 25 is located between the primary return air outlet 202 and the second surface cooler 24.

[0040] Typically, the underfloor air supply air conditioning unit 2 further includes a muffler unit 27 located in the second box 20, and the muffler unit 27 is disposed between the second blower 21 and the air outlet 204, and is used to reduce the noise introduced into the room. In this embodiment, the outlet of the air supply pipe 6 is located in the floor cavity, and there is not enough space in the floor cavity to install the muffler unit, so the muffler unit 27 is disposed in the second box 20. In other embodiments, if there is enough installation space, the muffler unit may not be installed in the second box 20, for example, it may be installed under the floor.

[0041] The number of controllers in this embodiment can be one, and all control adjustments are integrated in this controller. The number of controllers can also be two, and control boxes can be respectively set in the first box body 10 and the second box body 20 to place the controllers. The controller in the control box in the first box body 10 is respectively connected to the humidity sensor and the first regulating valve 28 through control signal lines, and the controller in the control box in the second box body 20 is respectively connected to the supply air temperature sensor, the return air temperature sensor, the carbon dioxide sensor, the fresh air regulating valve 22, the primary return air regulating valve 26, the secondary return air regulating valve 23, and the second regulating valve 29 through control signal lines.

[0042] It should be noted that references to "one embodiment", "an embodiment", "a specific embodiment", "some embodiments", etc. in the specification only indicate that the described embodiment may include a particular feature, structure or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. In addition, when a particular feature, structure or characteristic is described in conjunction with an embodiment, whether or not explicitly described, it is within the knowledge of a person skilled in the relevant art to implement such feature, structure or characteristic in conjunction with other embodiments.

[0043] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0044] It should also be noted that, although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the above disclosed technical content can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

[0045] It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are merely used to distinguish between the various components, elements, steps, etc. in the specification, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0046] It should also be recognized that the terms described herein are only used to describe specific embodiments and are not used to limit the scope of the utility model. It must be noted that the singular forms "one" and "a kind" used herein and in the appended claims include plural references unless the context clearly indicates the opposite meaning. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps and secondary devices. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have a logical "or" definition, rather than a logical "exclusive or" definition, unless the context clearly indicates the opposite meaning. In addition, the implementation of the method and / or device in the embodiment of the utility model may include performing the selected task manually, automatically, or in combination.

Claims

1. An air conditioning system, characterized in that: include: A fresh air air conditioning processing unit, comprising a first box, a first surface cooler and a first air blower, wherein the first box is provided with a fresh air inlet and a fresh air outlet, the first surface cooler and the first air blower are both located in the first box and between the fresh air inlet and the fresh air outlet, the first surface cooler is close to the fresh air inlet, and the first air blower is close to the fresh air outlet; An underfloor air supply air conditioning unit, comprising a second box, a second surface cooler and a second air supply fan, the second box is provided with an air inlet, a primary return air inlet, a secondary return air inlet and an air supply inlet, the air inlet is connected to the fresh air outlet through a fresh air duct, the primary return air inlet leads to the room through the primary return air duct, the secondary return air inlet leads to the room through the secondary return air duct, and the air supply inlet leads to the room through the air supply duct; the second surface cooler and the second air supply fan are located in the second box, and are sequentially arranged between the primary return air inlet and the air supply inlet, the secondary return air inlet and the air inlet are both located between the second surface cooler and the second air supply fan; The outlet of the air supply duct is located below the floor, and the inlets of the primary air return duct and the secondary air return duct are respectively close to the indoor ceiling.

2. The air conditioning system according to claim 1, characterized in that: A primary return air regulating valve is provided at the primary return air outlet, and a secondary return air regulating valve is provided at the secondary return air outlet.

3. The air conditioning system according to claim 2, characterized in that: The air conditioning system includes an air supply temperature sensor and a controller. The air supply temperature sensor is arranged on the air supply pipe. The air supply temperature sensor is communicatively connected to the controller. The controller is respectively connected to the primary return air regulating valve and the secondary return air regulating valve.

4. The air conditioning system according to claim 1, characterized in that: The first cooler is connected to a first water supply and return pipeline, and is connected to an air conditioning water system through the first water supply and return pipeline; the second cooler is connected to a second water supply and return pipeline, and is connected to an air conditioning water system through the second water supply and return pipeline.

5. The air conditioning system according to claim 4, characterized in that: There are two sets of the second supply and return water pipelines, one set of the second supply and return water pipelines is used to connect to the air-conditioning water system of the low-temperature cold source, and the other set of the second supply and return water pipelines is used to connect to the air-conditioning water system of the high-temperature cold source; the first supply and return water pipelines are used to connect to the air-conditioning water system of the low-temperature cold source; the water temperature of the air-conditioning water system of the high-temperature cold source is higher than the water temperature of the air-conditioning water system of the low-temperature cold source.

6. The air conditioning system according to claim 1, characterized in that: The fresh air air conditioning processing unit includes a fresh air filter unit located in the first box, and the fresh air filter unit is located between the fresh air inlet and the first surface cooler; the underfloor air supply air conditioning unit includes a return air filter unit located in the second box, and the return air filter unit is located between the primary return air outlet and the second surface cooler.

7. The air conditioning system according to claim 1, characterized in that: A fresh air regulating valve is provided at the air inlet of the second box.

8. The air conditioning system according to claim 7, characterized in that: The air conditioning system includes a controller and a carbon dioxide sensor arranged indoors, the carbon dioxide sensor is communicatively connected to the controller, and the controller is connected to the fresh air regulating valve.

9. The air conditioning system according to claim 1, characterized in that: The air conditioning system includes a controller, a return air temperature sensor and a humidity sensor. The humidity sensor is arranged indoors, and the return air temperature sensor is arranged on the primary return air duct and / or the secondary return air duct. The return air temperature sensor and the humidity sensor are respectively connected to the controller for communication, and the controller is respectively connected to the first surface cooler and the second surface cooler.

10. The air conditioning system according to claim 1, characterized in that: The underfloor air-supply air conditioning unit includes a silencer unit located in the second box, and the silencer unit is arranged between the second air blower and the air outlet.

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