Low-temperature refrigeration air conditioning system

Abstract

The utility model provides a low temperature refrigeration air-conditioning system, which comprises an air-conditioning outdoor unit and an air-conditioning indoor unit, and the air-conditioning outdoor unit comprises a medium voltage switch arranged on the low voltage side of the air-conditioning outdoor unit and used for detecting the pressure of the low voltage side; the condensation temperature sensor is arranged on the high-pressure side of the air conditioner outdoor unit and used for detecting the condensation temperature of the high-pressure side; the condensation temperature sensor is arranged on the outdoor unit heat exchanger, and the outdoor unit heat exchanger is further connected with the compressor and the liquid storage tank in sequence. The air conditioner indoor unit comprises an indoor unit heat exchanger; the indoor unit heat exchanger is connected with the outdoor unit heat exchanger and the liquid storage tank; the outdoor unit heat exchanger and the indoor unit heat exchanger are provided with an outer fan and an inner fan respectively. A medium-voltage switch on the high-voltage side is omitted and transferred to the low-voltage side, the exhaust temperature and the condensation temperature serve as feed-forward signals, fan gears are corrected and controlled in advance, and the purposes that the system is prevented from being damaged, and meanwhile it is guaranteed that the temperature and humidity needed by a scene are maintained within a certain range are achieved.

Description

Technical Field

[0001] The utility model relates to an air conditioning system, in particular to a low-temperature refrigeration air conditioning system, belonging to the technical field of refrigeration equipment. Background Art

[0002] With the development of the times and the development of agricultural food technology, refrigeration technology is not only used in high-temperature environments, but also plays a vital role in low-temperature environments. For example, the picking, storage, and transportation of vegetables and fruits require strict temperature control to maintain the freshness and shelf life of food. In agricultural production environments such as greenhouses and agricultural greenhouses, refrigeration technology can be used to adjust temperature and humidity to create a suitable growth environment. This requires the refrigeration system to have stable refrigeration and dehumidification capabilities in both summer and winter. When the refrigeration system is refrigerating in winter, due to the low inlet air temperature of the condenser, excessive air volume can easily cause low system pressure and insufficient suction and exhaust superheat, resulting in risks such as compressor liquid hammer damage or indoor unit heat exchanger icing. The industry usually uses a medium-pressure switch on the high-pressure side of the system to control the speed of the condensing side fan to ensure the superheat of the system. However, this control method still cannot accurately identify changes in the pressure on the low-pressure side, resulting in the performance of the evaporator fluctuating, unstable dehumidification capacity, and inability to stably maintain the scene needs. In addition, only focusing on the high-pressure side and ignoring the low-pressure side pressure will cause the system pressure ratio to be too large for a moment, causing compressor wear. Utility Model Content

[0003] In view of this, the utility model provides a low-temperature refrigeration air-conditioning system, which cancels the medium-pressure switch on the high-pressure side and transfers it to the low-pressure side, uses the exhaust temperature and condensing temperature as feedforward signals, and performs correction control on the fan gear in advance, so as to achieve the purpose of maintaining the required temperature and humidity of the scene within a certain range while avoiding damage to the system.

[0004] The technical solution of the embodiment of the utility model is implemented as follows: a low-temperature refrigeration air-conditioning system, comprising an air-conditioning outdoor unit and an air-conditioning indoor unit, the air-conditioning outdoor unit comprising: a medium-pressure switch arranged on the low-pressure side of the air-conditioning outdoor unit, used to detect the pressure on the low-pressure side; a condensing temperature sensor arranged on the high-pressure side of the air-conditioning outdoor unit, used to detect the condensing temperature on the high-pressure side; and the condensing temperature sensor is arranged on the outdoor unit heat exchanger, and the outdoor unit heat exchanger is also connected to the compressor and the liquid storage tank in sequence; the air-conditioning indoor unit comprises: an indoor unit heat exchanger; the indoor unit heat exchanger is connected to the outdoor unit heat exchanger and the liquid storage tank;

[0005] The external heat exchanger and the internal heat exchanger are respectively provided with an external fan and an internal fan.

[0006] Further preferably: the air conditioner outdoor unit further includes:

[0007] A high-pressure switch and an exhaust temperature sensor are arranged between the compressor and the external heat exchanger;

[0008] The exhaust temperature sensor is used to detect the exhaust temperature;

[0009] The high-pressure switch is located on a side close to the external heat exchanger;

[0010] The exhaust gas temperature sensor is located on a side close to the compressor.

[0011] Further preferably, the medium-pressure switch is arranged between the liquid storage tank and the indoor heat exchanger, and an air pipe stop valve is also arranged between the medium-pressure switch and the indoor heat exchanger.

[0012] Further preferably: the external unit heat exchanger is connected to a liquid pipe stop valve; the internal unit heat exchanger is connected to a throttle valve; and the liquid pipe stop valve is connected to the throttle valve.

[0013] Further preferably, the medium pressure switch is disconnected when the pressure is P1, and is reset when the pressure is P2, wherein P2 is greater than P1.

[0014] Further preferably, the exhaust temperature sensor and the condensing temperature sensor provide the exhaust temperature and the condensing temperature as feedforward signals to the air conditioner master control for adjusting the fan gear position and limiting the compressor power.

[0015] The embodiment of the utility model has the following advantages due to the adoption of the above technical solution:

[0016] The utility model divides the system state into multiple intervals by combining the evaporation pressure on the low-pressure side and the condensation temperature on the high-pressure side for collection, so that the main control can quickly and accurately judge the system state and make the system operation more stable; the medium-pressure switch is used to collect the low-pressure side pressure, which is lower in cost than using a pressure sensor; the utility model uses a low-pressure side pressure switch to control the start and stop of the compressor and the fan, which can effectively prevent the evaporator from freezing and the system pressure ratio from being too large.

[0017] The above summary is for the purpose of description only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the utility model will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a structural diagram of a preferred embodiment of the utility model.

[0020] Figure numerals: 1. compressor; 2. exhaust temperature sensor; 3. high-pressure switch; 4. external fan; 5. external unit heat exchanger; 6. condensing temperature sensor; 7. liquid pipe stop valve; 8. throttle valve; 9. internal fan; 10. internal unit heat exchanger; 11. gas pipe stop valve; 12. medium-pressure switch; 13. liquid storage tank; 100. air conditioner external unit; 200. air conditioner internal unit. DETAILED DESCRIPTION

[0021] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0022] The embodiments of the present utility model are described in detail below with reference to the accompanying drawings.

[0023] like Figure 1 As shown, a preferred embodiment, a low-temperature refrigeration air-conditioning system, includes an air-conditioning outdoor unit 100 and an air-conditioning indoor unit 200, the air-conditioning outdoor unit 100 includes: a medium-pressure switch 12 arranged on the low-pressure side of the air-conditioning outdoor unit 100, used to detect the pressure on the low-pressure side; a condensing temperature sensor 6 arranged on the high-pressure side of the air-conditioning outdoor unit 100, used to detect the condensing temperature on the high-pressure side; and the condensing temperature sensor 6 is arranged on the outdoor unit heat exchanger 5, and the outdoor unit heat exchanger 5 is also connected to the compressor 1 and the liquid storage tank 13 in sequence; the air-conditioning indoor unit 200 includes: an indoor unit heat exchanger 10; the indoor unit heat exchanger 10 is connected to the outdoor unit heat exchanger 5 and the liquid storage tank 13;

[0024] The external heat exchanger 5 and the internal heat exchanger 10 are provided with an external fan 4 and an internal fan 9 respectively.

[0025] In this embodiment, specifically: the air conditioner outdoor unit 100 further includes:

[0026] A high-pressure switch 3 and an exhaust temperature sensor 2 are arranged between the compressor 1 and the external heat exchanger 5;

[0027] The exhaust temperature sensor 2 is used to detect the exhaust temperature;

[0028] The high-voltage switch 3 is located on a side close to the external heat exchanger 5;

[0029] The exhaust temperature sensor 2 is located on a side close to the compressor 1 .

[0030] In this embodiment, specifically: the medium-pressure switch 12 is disposed between the liquid storage tank 13 and the indoor heat exchanger 10 , and an air pipe stop valve 11 is also disposed between the medium-pressure switch 12 and the indoor heat exchanger 10 .

[0031] In this embodiment, specifically: the external heat exchanger 5 is connected to the liquid pipe stop valve 7 ; the internal heat exchanger 10 is connected to the throttle valve 8 ; and the liquid pipe stop valve 7 is connected to the throttle valve 8 .

[0032] In this embodiment, specifically: the medium pressure switch 12 is disconnected when the pressure is P1, and is reset when the pressure is P2, wherein P2 is greater than P1.

[0033] In this embodiment, specifically: the exhaust temperature sensor 2 and the condensing temperature sensor 6 provide the exhaust temperature and the condensing temperature as feedforward signals to the air conditioner master control, which are used to adjust the fan gear position and limit the power of the compressor 1.

[0034] The working principle of the utility model embodiment, where the numerical values ​​are for illustration:

[0035] The medium-pressure switch 12 on the high-pressure side is removed and transferred to the low-pressure side. The disconnection pressure is P1 and the reset pressure is P2, where P2 is greater than P1. The pressure is divided into two intervals by P1. When the low pressure is greater than P1, the medium-pressure switch 12 is connected, and the main control determines that the evaporation side is in the high-pressure area. When the low pressure is less than or equal to P1, the medium-pressure switch 12 is disconnected, and the main control determines that the evaporation side is in the low-pressure area.

[0036] Set exhaust temperature sensor 2 and condensing temperature sensor 6, and use exhaust temperature and condensing temperature as feedforward signals

[0037] ① When the main control determines that the evaporation is in the high-pressure zone, the condensation temperature is divided into three intervals of A and B, where A>B. When the condensation temperature is greater than A, the main control determines that the condensation side is in the high-temperature zone, and the external fan 4 is increased by one gear every 25 seconds. When the condensation temperature is greater than B and less than A, the main control determines that the condensation side is in the constant temperature zone, and the system maintains the current state without change. When the condensation temperature is less than B, the main control determines that the condensation side is in the low-temperature zone, and the external fan 4 is reduced by one gear every 25 seconds, the lowest gear.

[0038] ② When the main control determines that the evaporation is in the low-pressure zone, the condensation temperature is divided into three intervals of C and D, where C>D. When the condensation temperature is greater than C, the main control determines that the condensation side is in the high-temperature zone, and the external fan 4 is increased by one gear every 25 seconds. When the condensation temperature is greater than D and less than C, the main control determines that the condensation side is in the constant temperature zone, and the system maintains the current state without change. When the condensation temperature is less than D, the main control determines that the condensation side is in the low-temperature zone, and the external fan 4 is reduced by one gear every 25 seconds, with the lowest gear being zero.

[0039] ③When the exhaust temperature is greater than E, the exhaust temperature is too high protection, and the compressor 1 is stopped. When it is less than F, it will resume

[0040] ④When the condensing temperature is greater than G, the condensing temperature is too high protection, and the compressor is stopped. When it is less than H, it will resume

[0041] ⑤ When the main control determines that the evaporation is in the low pressure area, and the exhaust temperature minus the condensing temperature is less than 5℃ for 10 minutes, the freeze protection is triggered, the compressor is stopped for 1 minute, and it is restored after 10 minutes.

[0042] Among them, P1=3℃ corresponds to the refrigerant saturation pressure, P2=5℃ corresponds to the refrigerant saturation pressure, condensation temperature A is equal to 32℃, condensation temperature B is equal to 27℃, condensation temperature C is equal to 45℃, condensation temperature D is equal to 33℃, condensation temperature G is equal to 65℃, condensation temperature H is equal to 48℃, exhaust temperature E is equal to 110℃, and exhaust temperature F is equal to 85℃.

[0043] Further understanding: In the air-conditioning system, the main control determines the initial speed according to the ambient temperature. The initial speed is maintained for 2 minutes or the condensing temperature is ≥45℃, and then it starts to adjust and increase to 3 gears; then it is controlled according to the condensing temperature and low-pressure switch.

[0044] like Figure 1 As shown, the medium-pressure switch 12 is located before the liquid storage tank 13 to detect the pressure value on the low-pressure side; the condensing temperature sensor 6 is on the external unit heat exchanger 5 to detect the condensing temperature on the high-pressure side; according to these two conditions, the system state can be divided into a high-pressure and high-temperature zone, a high-pressure constant temperature zone, a high-pressure and low-temperature zone, a low-pressure and high-temperature zone, a low-pressure constant temperature zone, and a low-pressure and low-temperature zone; the main control adopts corresponding adjustment methods according to the different state intervals of the system. In addition, the high-pressure switch 3, the exhaust temperature sensor 2, and the condensing temperature sensor 6 also have their own protection values ​​to prevent the system from operating outside the safe range, thereby ensuring that the system can operate stably while also completing the closed loop of protection.

[0045] The key point of the utility model is to use the medium-pressure switch 12 on the low-pressure side to timely sense the pressure changes on the evaporation side, and combine with the condensing temperature sensor 6 on the high-pressure side to divide the system state into intervals, so that the main control can quickly and accurately judge the system state, and thus make effective adjustments, so as to achieve the purpose of maintaining the temperature and humidity required by the scene within a certain range while avoiding damage to the system.

[0046] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A low-temperature refrigeration air conditioning system, comprising an air conditioning outdoor unit (100) and an air conditioning indoor unit (200), characterized in that: The air conditioner outdoor unit (100) comprises: a medium pressure switch (12) arranged on the low pressure side of the air conditioner outdoor unit (100) for detecting the pressure on the low pressure side; a condensation temperature sensor (6) arranged on the high pressure side of the air conditioner outdoor unit (100) for detecting the condensation temperature on the high pressure side; and the condensation temperature sensor (6) is arranged on the outdoor unit heat exchanger (5), and the outdoor unit heat exchanger (5) is also connected to the compressor (1) and the liquid storage tank (13) in sequence; the air conditioner indoor unit (200) comprises: an indoor unit heat exchanger (10); the indoor unit heat exchanger (10) is connected to the outdoor unit heat exchanger (5) and the liquid storage tank (13); The external heat exchanger (5) and the internal heat exchanger (10) are respectively provided with an external fan (4) and an internal fan (9).

2. The low temperature refrigeration air conditioning system according to claim 1, characterized in that: The air conditioner outdoor unit (100) further comprises: a high-pressure switch (3) and an exhaust temperature sensor (2) arranged between the compressor (1) and the outdoor unit heat exchanger (5); the exhaust temperature sensor (2) is used to detect the exhaust temperature; the high-pressure switch (3) is located on a side close to the outdoor unit heat exchanger (5); and the exhaust temperature sensor (2) is located on a side close to the compressor (1).

3. The low temperature refrigeration air conditioning system according to claim 1, characterized in that: The medium-pressure switch (12) is arranged between the liquid storage tank (13) and the indoor heat exchanger (10), and a gas pipe stop valve (11) is also arranged between the medium-pressure switch (12) and the indoor heat exchanger (10).

4. The low temperature refrigeration air conditioning system according to claim 1, characterized in that: The external heat exchanger (5) is connected to a liquid pipe stop valve (7); the internal heat exchanger (10) is connected to a throttle valve (8); and the liquid pipe stop valve (7) is connected to the throttle valve (8).

5. The low temperature refrigeration air conditioning system according to claim 1, characterized in that: The medium pressure switch (12) is disconnected when the pressure is P1, and is reset when the pressure is P2, wherein P2 is greater than P1.

6. The low temperature refrigeration air conditioning system according to claim 2, characterized in that: The exhaust temperature sensor (2) and the condensing temperature sensor (6) provide the exhaust temperature and the condensing temperature as feedforward signals to the air conditioner main control, which are used to adjust the fan gear position and limit the power of the compressor (1).

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