An air conditioning system for underground space and control method thereof

Abstract

The present invention discloses an air-conditioning system for an underground space and a control method thereof, the control method specifically comprising a process: presetting a first temperature value T1, a second temperature value T2, a second temperature control accuracy T3, and a normal value C1 of a carbon dioxide concentration in a control device; a first temperature sensor, a first humidity sensor, a second temperature sensor, and a second humidity sensor respectively feed back detection results to the control device; the control device calculates and compares a fresh air enthalpy value and a return air enthalpy value, if the fresh air enthalpy value is greater than the return air enthalpy value, the air-conditioning system turns on a cooling and dehumidifying mode, otherwise, the air-conditioning system turns on a ventilation mode; when the air-conditioning system is in the ventilation mode, if the actual return air temperature value is less than T2, the air-conditioning system turns on a heating mode; the control method for the underground space air-conditioning system provided by the present invention can adjust the working states of the fresh air unit and the return air unit according to the comparison result of the outdoor enthalpy value and the indoor enthalpy value, thereby reducing the energy consumption of the air-conditioning system while ensuring the air quality.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning systems, and in particular to an air conditioning system for an underground space and a control method thereof. Background Art

[0002] The underground space is a confined space with a large amount of human activities. Therefore, there are problems of high air humidity and high indoor carbon dioxide concentration in the underground space.

[0003] Due to the special environment of the underground space, the working status of the air-conditioning system of the underground space needs to be adjusted in time in different seasons; when it is summer, the air-conditioning system needs to dehumidify and cool the underground space; when it is in the transition season, the air-conditioning system needs to keep the underground space ventilated; when it is winter, the air-conditioning system needs to keep the underground space ventilated and ensure that the temperature of the underground space is not too low.

[0004] In the current market, the air-conditioning system of underground space has a single function and cannot take into account both indoor air quality and energy consumption. In other words, it cannot ensure the indoor comfort and cleanliness of the underground space while taking into account energy saving.

[0005] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an air-conditioning system for an underground space and a control method thereof. The control device can adjust the working states of the fresh air unit and the return air unit according to the comparison results of the outdoor enthalpy value and the indoor enthalpy value, thereby reducing the energy consumption of the air-conditioning system while ensuring the air quality.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A control method for an underground space air conditioning system comprises the following steps:

[0009] S100, presetting a first temperature value T1, a second temperature value T2, a second temperature control accuracy T3, and a normal value C1 of carbon dioxide concentration in a control device;

[0010] S200, the first temperature sensor and the first humidity sensor arranged at the fresh air inlet feed back the detected actual fresh air temperature value T4 and the actual fresh air humidity value to the control device; the second temperature sensor and the second humidity sensor arranged at the return air inlet feed back the detected actual return air temperature value T5 and the actual return air humidity value to the control device;

[0011] S300, the control device calculates and compares the fresh air enthalpy value and the return air enthalpy value, if the fresh air enthalpy value is greater than the return air enthalpy value, then execute step S400, otherwise, execute step S500;

[0012] S400, the air conditioning system starts the cooling and dehumidification mode, the control device controls to increase the opening of the third regulating water valve arranged at the water inlet of the second cooling coil, if the opening of the third regulating water valve is the maximum and T5>T1; the control device controls to increase the opening of the first regulating water valve arranged at the water inlet of the first cooling coil; if the opening of the first regulating water valve is the maximum and T5>T1; the control device controls to increase the opening of the fresh air valve and the return air valve;

[0013] S500, the air conditioning system starts the ventilation mode, the control device controls the closing of the return air valve and the third regulating water valve, if T5>T1, the control device controls to increase the opening of the first regulating water valve arranged at the water inlet of the first surface cooling coil; if T5 is still greater than T1, the control device controls to increase the opening of the fresh air valve; if T5<T2, execute step S600;

[0014] S600, the air-conditioning system starts the heating mode, the control device controls the closing of the first regulating water valve and the second regulating water valve, and controls the opening of the return air valve, and increases the opening of the return air valve as the actual return air temperature decreases; if the return air valve opening is at the maximum and T5<T2, the control device controls the opening of the second regulating water valve arranged on the first heating coil, and increases the opening of the second regulating water valve as the actual return air temperature decreases; if the opening of the second regulating water valve is at the maximum and T5<T2, the control device controls the opening of the fourth regulating water valve arranged on the second heating coil, and increases the opening of the fourth regulating water valve as the actual return air temperature decreases.

[0015] In the control method of the underground space air conditioning system, the step S400 further includes the steps of:

[0016] S410. The carbon dioxide concentration meter installed in the underground space feeds back the actual carbon dioxide concentration value C2 detected to the control device. If C2>C1, the control device controls to increase the opening of the fresh air valve and adjusts the opening of the return air valve according to the opening of the fresh air valve.

[0017] In the control method of the underground space air conditioning system, the step S500 further includes the steps of:

[0018] S510. The carbon dioxide concentration meter installed in the underground space feeds back the detected actual carbon dioxide concentration value C2 to the control device. If C2>C1, the control device controls to increase the opening of the fresh air valve.

[0019] In the control method of the underground space air conditioning system, the step S600 further includes the steps of:

[0020] S610. The carbon dioxide concentration meter installed in the underground space feeds back the actual carbon dioxide concentration value C2 detected to the control device. If C2>C1, the control device controls to increase the opening of the fresh air valve and adjusts the opening of the return air valve according to the opening of the fresh air valve.

[0021] The present invention also provides an air-conditioning system for an underground space, comprising a control device and a shell, and a fresh air unit, a return air unit and an air supply unit arranged in sequence along the air inlet and outlet direction of the shell, the fresh air unit comprising a fresh air inlet opened on the shell and a fresh air processing mechanism arranged in the shell and located at the rear side of the fresh air inlet, the return air unit comprising a return air inlet opened on the shell and a return air processing mechanism arranged in the shell and located at the rear side of the return air inlet; a fresh air valve, a first temperature sensor and a first humidity sensor are arranged at the fresh air inlet, and a return air valve, a second temperature sensor and a second humidity sensor are arranged at the return air inlet, and the fresh air valve, the return air valve, the first temperature sensor, the first humidity sensor, the second temperature sensor and the second humidity sensor are electrically connected to the control device respectively.

[0022] In the air conditioning system for the underground space, the air supply unit includes an air supply fan, a second filter and an air supply port which are arranged in sequence along the air inlet and outlet directions of the shell. The air supply fan is arranged in the shell, and the air supply port is opened at the top of the shell.

[0023] In the air-conditioning system of the underground space, the fresh air processing mechanism includes a first filter, a first surface cooling coil, a first heating coil and a water baffle arranged in sequence along the air inlet and outlet directions of the shell; a first regulating water valve is arranged at the water inlet of the first surface cooling coil, and a second regulating water valve is arranged at the water inlet of the first heating coil; the first regulating water valve and the second regulating water valve are electrically connected to the control device respectively.

[0024] In the air-conditioning system of the underground space, the return air processing mechanism includes a second surface cooling coil and a second heating coil arranged in sequence along the air inlet and outlet direction of the shell; a third regulating water valve is arranged at the water inlet of the second surface cooling coil, and a fourth regulating water valve is arranged at the water inlet of the second heating coil; the third regulating water valve and the fourth regulating water valve are electrically connected to the control device respectively.

[0025] The air-conditioning system for the underground space also includes a first inspection unit, a second inspection unit, a third inspection unit and a fourth inspection unit; the first inspection unit is arranged between the fresh air inlet and the fresh air processing mechanism, the second inspection unit is arranged between the return air inlet and the return air processing mechanism, the third inspection unit is arranged between the return air processing mechanism and the air supply fan, and the fourth inspection unit is arranged between the air supply fan and the second filter; the inspection unit includes an inspection door arranged on the shell and an inspection light arranged in the shell, and the inspection light is arranged at the top of the shell.

[0026] The air conditioning system for the underground space also includes a carbon dioxide concentration meter arranged in the underground space, and the carbon dioxide concentration meter is electrically connected to the control device.

[0027] Beneficial effects:

[0028] The present invention provides an air-conditioning system for an underground space and a control method thereof. A control device compares a calculated indoor enthalpy value with an outdoor enthalpy value. According to the comparison result, the air-conditioning system selects to start a cooling and dehumidification mode, a ventilation mode or a heating mode respectively. In different modes, the control device controls and adjusts the working states of a fresh air unit and a return air unit respectively to ensure the environmental comfort of the underground space. The working states of the fresh air unit and the return air unit are adjusted according to different conditions and different requirements to reduce the energy consumption of the air-conditioning system when it is working, thereby achieving an energy-saving effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A control flow chart of the air conditioning system control method provided by the present invention;

[0030] Figure 2 A control flow chart of the cooling and dehumidification mode provided by the present invention;

[0031] Figure 3 A control flow chart of the ventilation mode and the heating mode provided by the present invention;

[0032] Figure 4 A schematic structural diagram of the air conditioning system for an underground space provided by the present invention.

[0033] Explanation of main component symbols: 11-fresh air inlet, 12-fresh air treatment mechanism, 121-first filter, 122-first surface cooling coil, 123-first heating coil, 124-water baffle, 21-return air inlet, 22-return air treatment mechanism, 221-second surface cooling coil, 222-second heating coil, 31-air supply fan, 32-air supply outlet, 33-second filter, 4-first maintenance unit, 5-second maintenance unit, 6-third maintenance unit, 7-fourth maintenance unit.

[0034] Figure 4The arrow direction indicates the wind flow direction. DETAILED DESCRIPTION

[0035] The present invention provides an air conditioning system for an underground space and a control method thereof. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0036] In the description of the present invention, it should be understood that the terms "top", "rear", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; in addition, unless otherwise clearly specified and limited, the terms "installation", "connection", etc. should be understood in a broad sense, and those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific circumstances.

[0037] See also Figures 1 to 3 The present invention provides a control method for an underground space air conditioning system, comprising the following steps:

[0038] S100, presetting a first temperature value T1, a second temperature value T2, a second temperature control accuracy T3, and a normal value C1 of carbon dioxide concentration in the control device; in this embodiment, the first temperature value T1 is a suitable ambient temperature of the underground space in summer; the second temperature value T2 is a suitable ambient temperature of the underground space in winter, and the second temperature value T2 may be, but not limited to, 15°C; the second temperature control accuracy T3 may be, but not limited to, 3°C, and the normal value of carbon dioxide concentration is set according to the average population density of the underground space;

[0039] S200, the first temperature sensor and the first humidity sensor arranged at the fresh air inlet 11 feed back the detected actual fresh air temperature value T4 and the actual fresh air humidity value to the control device; the second temperature sensor and the second humidity sensor arranged at the return air inlet 21 feed back the detected actual return air temperature value T5 and the actual return air humidity value to the control device;

[0040] S300, the control device calculates and compares the fresh air enthalpy value and the return air enthalpy value, if the fresh air enthalpy value is greater than the return air enthalpy value, then execute step S400, otherwise, execute step S500;

[0041] S400, the air conditioning system starts the cooling and dehumidification mode, the control device controls to increase the opening of the third regulating water valve arranged at the water inlet of the second surface cooling coil 221, if the opening of the third regulating water valve is the maximum and T5>T1; the control device controls to increase the opening of the first regulating water valve arranged at the water inlet of the first surface cooling coil 122; if the opening of the first regulating water valve is the maximum and T5>T1; the control device controls to increase the opening of the fresh air valve and the return air valve;

[0042] S500, the air conditioning system starts the ventilation mode, the control device controls the closing of the return air valve and the third regulating water valve, if T5>T1, the control device controls to increase the opening of the first regulating water valve arranged at the water inlet of the first surface cooling coil 122; if T5 is still greater than T1, the control device controls to increase the opening of the fresh air valve; if T5<T2, execute step S600;

[0043] S600, the air-conditioning system starts the heating mode, the control device controls the closing of the first regulating water valve and the second regulating water valve, and controls the opening of the return air valve, and increases the opening of the return air valve as the actual return air temperature decreases; if the return air valve opening is at its maximum and T5<T2, the control device controls the opening of the second regulating water valve arranged on the first heating coil 123, and increases the opening of the second regulating water valve as the actual return air temperature decreases; if the opening of the second regulating water valve is at its maximum and T5<T2, the control device controls the opening of the fourth regulating water valve arranged on the second heating coil 222, and increases the opening of the fourth regulating water valve as the actual return air temperature decreases; through adjustment, the actual return air temperature is maintained within the range of T2+T3.

[0044] The present invention provides a control method for an underground space air-conditioning system. In a cooling and dehumidification mode, a ventilation mode and a heating mode, a control device controls and adjusts the working states of a fresh air unit and a return air unit, and the adjustment methods of the fresh air unit and the return air unit are changed according to different conditions, thereby reducing the energy consumption of the air-conditioning system while ensuring the comfort of the underground space environment.

[0045] For further information, see Figure 2 , the step S400 further comprises the steps of:

[0046] S410. The carbon dioxide concentration meter installed in the underground space will feed back the actual carbon dioxide concentration value C2 detected to the control device. If C2>C1, the control device will control the opening of the fresh air valve to increase, and adjust the opening of the return air valve according to the opening of the fresh air valve. When the opening of the fresh air valve increases, the return air intake volume can be appropriately reduced.

[0047] For further information, see Figure 3 , the step S500 further comprises the steps of:

[0048] S510. The carbon dioxide concentration meter installed in the underground space feeds back the actual carbon dioxide concentration value C2 detected to the control device. If C2>C1, since the return air valve is in a closed state at this time, the control device controls to increase the opening of the fresh air valve.

[0049] For further information, see Figure 3 , the step S600 further comprises the steps of:

[0050] S610. The carbon dioxide concentration meter installed in the underground space will feed back the actual carbon dioxide concentration value C2 detected to the control device. If C2>C1, the control device will control the opening of the fresh air valve to increase, and adjust the opening of the return air valve according to the opening of the fresh air valve. When the opening of the fresh air valve increases, the return air intake volume can be appropriately reduced.

[0051] The air-conditioning system conducts real-time detection of the carbon dioxide concentration in the underground space in the cooling and dehumidification mode, ventilation mode and heating mode, and adjusts the fresh air intake according to the actual carbon dioxide concentration detection value to ensure that the carbon dioxide concentration in the underground space is not too high, thereby improving the environmental comfort of the underground space.

[0052] For further information, see Figure 4 The present invention also provides an air conditioning system for an underground space, comprising a control device and a shell, and a fresh air unit, a return air unit and an air supply unit arranged in sequence along the air inlet and outlet direction of the shell, the fresh air unit comprising a fresh air inlet 11 opened on the shell and a fresh air processing mechanism 12 arranged in the shell and located at the rear side of the fresh air inlet 11, the return air unit comprising a return air inlet 21 opened on the shell and a return air processing mechanism 22 arranged in the shell and located at the rear side of the return air inlet 21; a fresh air valve, a first temperature sensor and a first humidity sensor are arranged at the fresh air inlet 11, a return air valve, a second temperature sensor and a second humidity sensor are arranged at the return air inlet 21, and the fresh air valve, the return air valve, the first temperature sensor, the first humidity sensor, the second temperature sensor and the second humidity sensor are electrically connected to the control device respectively.

[0053] In this embodiment, the control device may be, but is not limited to, a PLC control system. The return air inlet 21 is opened at the top of the shell, and the fresh air inlet 11 is opened at the air inlet side of the shell.

[0054] Furthermore, the air supply unit includes an air supply fan 31, a second filter 33 and an air supply port 32 which are arranged in sequence along the air inlet and outlet directions of the shell, the air supply fan 31 is arranged in the shell, and the air supply port 32 is opened at the top of the shell; the treated fresh air and return air are delivered to the underground space through the air supply fan 31 and the air supply port 32; the second filter 33 is used to filter the treated mixed fresh return air to improve the cleanliness of the air delivered to the underground space; in this embodiment, the second filter 33 can be but is not limited to a bag filter.

[0055] Furthermore, the fresh air treatment mechanism 12 includes a first filter 121, a first cooling coil 122, a first heating coil 123 and a water baffle 124, which are arranged in sequence along the air inlet and outlet directions of the shell; a first regulating water valve for adjusting the water inlet amount of the first cooling coil 122 is arranged at the water inlet of the first cooling coil 122, and a second regulating water valve for adjusting the water inlet amount of the first heating coil 123 is arranged at the water inlet of the first heating coil 123; the first regulating water valve and the second regulating water valve are electrically connected to the control device respectively, and the control device can control and adjust the opening of the first regulating water valve and the second regulating water valve.

[0056] Providing the first filter 121 can improve the cleanliness of the fresh air and indirectly improve the cleanliness of the air entering the underground space. In the present embodiment, the first filter 121 can be but is not limited to a flat filter; and the water baffle 124 can effectively block the water vapor in the fresh air and reduce the water vapor content of the fresh air, thereby reducing the humidity of the air entering the underground space and avoiding an increase in the workload of the air conditioning system due to the high humidity of the air in the underground space.

[0057] Furthermore, the return air processing mechanism 22 includes a second cooling coil 221 and a second heating coil 222 arranged in sequence along the air inlet and outlet direction of the shell; a third regulating water valve for adjusting the water inlet amount of the second cooling coil 221 is arranged at the water inlet of the second cooling coil 221, and a fourth regulating water valve for adjusting the water inlet amount of the second heating coil 222 is arranged at the water inlet of the second heating coil 222; the third regulating water valve and the fourth regulating water valve are electrically connected to the control device respectively, and the control device can control and adjust the opening of the third regulating water valve and the fourth regulating water valve.

[0058] Furthermore, the air-conditioning system of the underground space also includes a first inspection unit 4, a second inspection unit 5, a third inspection unit 6 and a fourth inspection unit 7; the first inspection unit 4 is arranged between the fresh air inlet 11 and the fresh air processing mechanism 12, the second inspection unit 5 is arranged between the return air inlet 21 and the return air processing mechanism 22, the third inspection unit 6 is arranged between the return air processing mechanism 22 and the air supply fan 31, and the fourth inspection unit 7 is arranged between the air supply fan 31 and the second filter 33; the inspection unit includes an inspection door arranged on the shell and an inspection light arranged in the shell, and the inspection light is arranged at the top of the shell.

[0059] A first maintenance unit 4, a second maintenance unit 5, a third maintenance unit 6 and a fourth maintenance unit 7 are provided, so that when an error occurs inside the air-conditioning system, it is convenient for the operation and maintenance personnel to enter the air-conditioning system for maintenance, and it is also convenient for the operation and maintenance personnel to perform daily maintenance work on the air-conditioning system; the maintenance unit includes a maintenance light, which can provide light for the operation and maintenance personnel, thereby improving the convenience of the operation and maintenance personnel when performing maintenance work; in this embodiment, the maintenance door is hinged to the shell by hinges, and the maintenance light is bolted to the shell, and the maintenance light can be but is not limited to a voice-controlled light.

[0060] Furthermore, the air-conditioning system of the underground space also includes a carbon dioxide concentration meter arranged in the underground space, and the carbon dioxide concentration meter is electrically connected to the control device; the carbon dioxide concentration meter feeds back the detected actual carbon dioxide concentration C2 of the underground space to the control device, and the control device compares C2 and C1, and adjusts the opening of the fresh air valve and the return air valve to change the air intake volume of the fresh air and the return air.

[0061] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the present invention.

Claims

1. A control method for an underground space air conditioning system, characterized in that: The air conditioning system of the underground space includes a control device and a shell, and a fresh air unit, a return air unit and an air supply unit arranged in sequence along the air inlet and outlet direction of the shell, the fresh air unit includes a fresh air inlet opened on the shell and a fresh air processing mechanism arranged in the shell and located at the rear side of the fresh air inlet, the return air unit includes a return air inlet opened on the shell and a return air processing mechanism arranged in the shell and located at the rear side of the return air inlet; a fresh air valve, a first temperature sensor and a first humidity sensor are arranged at the fresh air inlet, and a return air valve, a second temperature sensor and a second humidity sensor are arranged at the return air inlet, and the fresh air valve, the return air valve, the first temperature sensor, the first humidity sensor, the second temperature sensor and the second humidity sensor are respectively connected to the control device The fresh air treatment mechanism comprises a first filter, a first cooling coil, a first heating coil and a water baffle arranged in sequence along the air inlet and outlet direction of the shell; a first regulating water valve is arranged at the water inlet of the first cooling coil, and a second regulating water valve is arranged at the water inlet of the first heating coil; the first regulating water valve and the second regulating water valve are electrically connected to the control device respectively; the return air treatment mechanism comprises a second cooling coil and a second heating coil arranged in sequence along the air inlet and outlet direction of the shell; a third regulating water valve is arranged at the water inlet of the second cooling coil, and a fourth regulating water valve is arranged at the water inlet of the second heating coil; the third regulating water valve and the fourth regulating water valve are electrically connected to the control device respectively; the control method comprises the following steps: S100, presetting a first temperature value T1, a second temperature value T2, a second temperature control accuracy T3, and a normal value C1 of carbon dioxide concentration in a control device; S200, the first temperature sensor and the first humidity sensor arranged at the fresh air inlet feed back the detected actual fresh air temperature value T4 and the actual fresh air humidity value to the control device; the second temperature sensor and the second humidity sensor arranged at the return air inlet feed back the detected actual return air temperature value T5 and the actual return air humidity value to the control device; S300, the control device calculates and compares the fresh air enthalpy value and the return air enthalpy value, if the fresh air enthalpy value is greater than the return air enthalpy value, then execute step S400, otherwise, execute step S500; S400, the air conditioning system starts the cooling and dehumidification mode, the control device controls to increase the opening of the third regulating water valve arranged at the water inlet of the second cooling coil, if the opening of the third regulating water valve is the maximum and T5>T1; the control device controls to increase the opening of the first regulating water valve arranged at the water inlet of the first cooling coil; if the opening of the first regulating water valve is the maximum and T5>T1; the control device controls to increase the opening of the fresh air valve and the return air valve; S500, the air conditioning system starts the ventilation mode, the control device controls the closing of the return air valve and the third regulating water valve, if T5>T1, the control device controls to increase the opening of the first regulating water valve arranged at the water inlet of the first surface cooling coil; if T5 is still greater than T1, the control device controls to increase the opening of the fresh air valve; if T5<T2, execute step S600; S600, the air-conditioning system starts the heating mode, the control device controls the closing of the first regulating water valve and the second regulating water valve, and controls the opening of the return air valve, and increases the opening of the return air valve as the actual return air temperature decreases; if the return air valve opening is at the maximum and T5<T2, the control device controls the opening of the second regulating water valve arranged on the first heating coil, and increases the opening of the second regulating water valve as the actual return air temperature decreases; if the opening of the second regulating water valve is at the maximum and T5<T2, the control device controls the opening of the fourth regulating water valve arranged on the second heating coil, and increases the opening of the fourth regulating water valve as the actual return air temperature decreases.

2. The control method of an underground space air conditioning system according to claim 1, characterized in that: The air conditioning system of the underground space further includes a carbon dioxide concentration meter disposed in the underground space, and the carbon dioxide concentration meter is electrically connected to the control device; the step S400 further includes the steps of: S410. The carbon dioxide concentration meter installed in the underground space feeds back the actual carbon dioxide concentration value C2 detected to the control device. If C2>C1, the control device controls to increase the opening of the fresh air valve and adjusts the opening of the return air valve according to the opening of the fresh air valve.

3. The control method of an underground space air conditioning system according to claim 1, characterized in that: The step S500 further includes the steps of: S510. The carbon dioxide concentration meter installed in the underground space feeds back the detected actual carbon dioxide concentration value C2 to the control device. If C2>C1, the control device controls to increase the opening of the fresh air valve.

4. The control method of an underground space air conditioning system according to claim 1, characterized in that: The step S600 further includes the steps of: S610. The carbon dioxide concentration meter installed in the underground space feeds back the actual carbon dioxide concentration value C2 detected to the control device. If C2>C1, the control device controls to increase the opening of the fresh air valve and adjusts the opening of the return air valve according to the opening of the fresh air valve.

5. An air conditioning system for an underground space, characterized in that: The air conditioning system of the underground space adopts the control method of the air conditioning system of the underground space as described in any one of claims 1-4 to realize operation control.

6. An underground space air conditioning system according to claim 5, characterized in that: The air supply unit comprises an air supply fan, a second filter and an air supply port which are sequentially arranged along the air inlet and outlet directions of the shell. The air supply fan is arranged in the shell, and the air supply port is opened at the top of the shell.

7. An underground space air conditioning system according to claim 6, characterized in that: It also includes a first inspection unit, a second inspection unit, a third inspection unit and a fourth inspection unit; the first inspection unit is arranged between the fresh air inlet and the fresh air processing mechanism, the second inspection unit is arranged between the return air inlet and the return air processing mechanism, the third inspection unit is arranged between the return air processing mechanism and the air supply fan, and the fourth inspection unit is arranged between the air supply fan and the second filter; the inspection unit includes an inspection door arranged on the shell and an inspection light arranged in the shell, and the inspection light is arranged at the top of the shell.

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