Condensing heat recovery constant temperature and humidity air conditioning system and defrosting control method thereof

Abstract

The application discloses a condensation heat recovery constant temperature and humidity air conditioning system and a defrosting control method thereof. The system comprises a constant temperature and humidity unit; the constant temperature and humidity unit comprises a shell, a fresh air temperature probe, a first heat exchanger, a second heat exchanger, an outlet air temperature probe, a humidifier and a supply fan which are arranged in the shell in sequence along the air direction, and a compressor, a four-way valve, an outdoor heat exchanger and an outdoor fan which are arranged outside the shell; in the defrosting state, the four-way valve is reversed, one way of the output end of the compressor passes through a reheating electric ball valve, the second heat exchanger, an electronic expansion valve and the first heat exchanger and is then connected to the input end of the compressor through the four-way valve, and the other way of the output end of the compressor passes through the four-way valve, a condensation electric ball valve, the outdoor heat exchanger, the electronic expansion valve and the first heat exchanger and is then connected to the input end of the compressor through the four-way valve. The application maintains the indoor temperature during defrosting by replacing electric heating with condensation heat, thereby saving cost and reducing energy consumption.

Description

Technical Field

[0001] This invention relates to the field of air conditioning control technology, and in particular to a condensation heat recovery constant temperature and humidity air conditioning system and its defrosting control method. Background Technology

[0002] Constant temperature and humidity air conditioners are mostly used in applications where temperature and humidity accuracy requirements are particularly high, such as in the electronics industry, instrumentation, precision machinery, bioengineering, food and beverage, and pharmaceutical and health industries. The accuracy of temperature and humidity in these environments directly affects product quality and storage.

[0003] In heating mode, the outdoor heat exchanger of a constant temperature and humidity air conditioning system often frosts up, affecting the heating performance. Therefore, timely defrosting of the outdoor heat exchanger is necessary. Currently, the traditional defrosting control method involves reversing the four-way valve to allow the refrigerant to flow in reverse, and using electric heating to compensate and maintain indoor temperature and humidity during defrosting. However, this method has low control precision and is prone to large temperature and humidity fluctuations, which can cause irreversible damage to industries such as electronics, instrumentation, precision machinery, bioengineering, food and beverage, and pharmaceuticals. In addition, the use of electric heating results in high initial investment and high energy consumption for the unit. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a condensation heat recovery constant temperature and humidity air conditioning system and its defrosting control method, which solves the technical problems of high initial investment and high energy consumption in the traditional constant temperature and humidity air conditioning system that uses electric heating to compensate for defrosting during defrosting.

[0005] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution:

[0006] In a first aspect, the present invention provides a condensing heat recovery constant temperature and humidity air conditioning system, including a constant temperature and humidity unit; the constant temperature and humidity unit includes a housing, a fresh air temperature probe, a first heat exchanger, a second heat exchanger, an outlet air temperature probe, a humidifier, and a blower arranged sequentially along the airflow direction inside the housing, a compressor, a four-way valve, an outdoor heat exchanger, and an outdoor fan arranged outside the housing; in the defrost state, the four-way valve reverses, and one output of the compressor is connected to the input of the compressor via a reheat electric ball valve, a second heat exchanger, an electronic expansion valve, and a first heat exchanger, and then via the four-way valve; the other output of the compressor is connected to the input of the compressor via the four-way valve, a condensing electric ball valve, an outdoor heat exchanger, an electronic expansion valve, and a first heat exchanger, and then via the four-way valve.

[0007] In conjunction with the first aspect, preferably, in the heating state of the air conditioning system, one output of the compressor is connected to the input of the compressor via a reheat electric ball valve, a second heat exchanger, an outdoor heat exchanger, a condensing electric ball valve, and then via a four-way valve; the other output of the compressor is connected to the input of the compressor via a four-way valve, a first heat exchanger, an electronic expansion valve, an outdoor heat exchanger, a condensing electric ball valve, and then via a four-way valve.

[0008] In conjunction with the first aspect, preferably, it also includes a constant temperature and humidity chamber, wherein the constant temperature and humidity unit is connected to the constant temperature and humidity chamber via an air supply duct.

[0009] In conjunction with the first aspect, preferably, the constant temperature and humidity chamber is equipped with an exhaust fan, the outlet of the exhaust fan is connected to an exhaust duct, and a temperature and humidity sensor is installed on the exhaust duct.

[0010] In conjunction with the first aspect, preferably, a condensing pressure sensor is installed on the pipeline between the output end of the compressor and the four-way valve; an evaporating pressure sensor is installed on the pipeline between the four-way valve and the input end of the compressor; and a compressor top temperature sensor and a compressor bottom temperature sensor are respectively installed at both ends of the compressor.

[0011] In conjunction with the first aspect, preferably, the adjustment range of the condensing electric ball valve and the reheat electric ball valve is both 0-3000p. In a second aspect, the present invention provides a defrosting control method applicable to any of the condensing heat recovery constant temperature and humidity air conditioning systems described in the first aspect, the method comprising:

[0012] When the air conditioning system reaches the defrosting condition as monitored, the compressor frequency is adjusted to H1, where H1 represents the preset first frequency;

[0013] After ensuring that the frequency of the compressor is stable at H1 within a preset first time interval, close the four-way valve to make the four-way valve switch, and at the same time adjust the opening of the condensing electric ball valve to a preset first opening and adjust the opening of the electronic expansion valve to a preset second opening.

[0014] After the preset second time interval, the compressor frequency is adjusted to H2, the outdoor fan is turned off, and the frequencies of both the supply fan and the exhaust fan are adjusted to H. Here, H2 represents the preset second frequency, and H represents the defrosting frequency.

[0015] When the defrosting conditions are met, adjust the compressor frequency to H1;

[0016] After ensuring that the frequency of the compressor is stable at H1 within the preset first time interval, open the four-way valve to make the four-way valve switch again, and at the same time adjust the opening of the condensing electric ball valve back to 3000p and the opening of the electronic expansion valve back to the normal operating opening.

[0017] After the preset second time interval, the frequencies of the compressor, blower, and exhaust fan are all adjusted back to their respective normal operating frequencies, and the outdoor fan is turned on at the same time.

[0018] In conjunction with the second aspect, preferably, the preset first opening is 1000p, and the preset second opening is 180p.

[0019] In conjunction with the second aspect, preferably, the determination step for the air conditioning system to reach the defrosting condition includes:

[0020] The compressor mechanism detects the fresh air temperature after a hot start-up.

[0021] If the fresh air temperature is ≤X, then monitor whether the compressor heating operation time T satisfies T≥Y; if T≥Y is satisfied, then periodically monitor the fresh air temperature, compressor frequency, and exhaust air temperature and humidity sensor temperature, and calculate the fresh air temperature change rate a1, compressor frequency change rate a2, and exhaust air temperature change rate a3 in the current cycle respectively. Calculate a based on a1 and a2: a=a1 / (a2*0.24); where X represents the preset temperature threshold and Y represents the preset first time threshold.

[0022] If a≤0.8 and a3≤-2, then directly enter defrost mode; otherwise, wait until the compressor hot running time T≥Q before entering defrost mode, where Q>Y, and Q represents the preset second time threshold.

[0023] If the fresh air temperature is greater than X, then the defrosting mode will be entered when the compressor's heating operation time is greater than or equal to Z, where Z > Y and Z represents the preset third time threshold.

[0024] In conjunction with the second aspect, preferably, X is 12℃; Y is 40min; Z is 120min; Q is 80min; and the monitoring cycle for the fresh air temperature, compressor frequency, and exhaust air temperature and humidity sensor temperature is 40 seconds / time.

[0025] In conjunction with the second aspect, preferably, the conditions for reaching the end of defrosting include:

[0026] The pressure detected by the condensing pressure sensor is greater than or equal to the preset condensing pressure threshold, or the compressor top temperature is greater than or equal to the preset temperature threshold, or the defrosting time is greater than or equal to the preset time threshold.

[0027] In conjunction with the second aspect, preferably, the value range of H1 is 30Hz to 50Hz; the value range of H2 is 70Hz to 90Hz; the value range of H is 20Hz to 50Hz; and both the first time interval and the second time interval are 5 seconds.

[0028] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0029] When the condensing heat recovery constant temperature and humidity air conditioning system provided by the present invention is running in defrost mode, the first heat exchanger is converted into an evaporator, the outdoor heat exchanger is converted into a condenser for defrosting, and the second heat exchanger is converted into a condenser. The first end of the second heat exchanger is directly connected to the compressor exhaust port. The temperature of the constant temperature and humidity room during defrosting is maintained by replacing the traditional electric heating method with condensing heat, which not only reduces costs but also has low energy consumption.

[0030] The defrosting control method provided by this invention calculates the fresh air temperature change rate a1, the compressor frequency change rate a2, and the return air temperature change rate a3 to determine whether to enter the defrosting condition, making the defrosting cycle more reasonable and effectively avoiding the occurrence of false defrosting.

[0031] This invention integrates defrosting time and indoor temperature and humidity fluctuations. During defrosting, the opening degree of the reheat electric ball valve is controlled at 3000p, and the opening degree of the condensing electric ball valve is controlled at 1000p, so that part of the condensing load is used for defrosting and part is used to maintain the indoor temperature. At the same time, the frequency of the supply fan and exhaust fan is reduced, which greatly reduces the fluctuation of indoor temperature and humidity without changing the indoor pressure difference. Attached Figure Description

[0032] Figure 1 This is a structural schematic diagram of a condensation heat recovery constant temperature and humidity air conditioning system provided in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the control logic for a defrosting control method of a condensing heat recovery constant temperature and humidity air conditioning system provided in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the process for determining whether an air conditioning system meets the conditions for entering defrosting, provided in an embodiment of the present invention.

[0035] In the diagram: 1. Housing; 1-1. Fresh air temperature probe; 1-2. First heat exchanger; 1-3. Second heat exchanger; 1-4. Outlet air temperature probe; 1-5. Humidifier; 1-6. Supply fan; 1-7. Electronic expansion valve; 1-8. Temperature and humidity sensor; 2. Compressor; 3. Condensing pressure sensor; 4. Condensing electric ball valve; 5. Reheat electric ball valve; 6. Outdoor heat exchanger; 7. Outdoor fan; 8. Evaporating pressure sensor; 9. Compressor bottom temperature; 10. Four-way valve; 11. Compressor top temperature sensor; 12. Supply air duct; 13. Exhaust air duct; 14. Constant temperature and humidity chamber; 15. Exhaust fan. Detailed Implementation

[0036] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments and specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations thereof. In the absence of conflict, the embodiments and technical features in the embodiments can be combined with each other.

[0037] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0038] Example 1:

[0039] like Figure 1 As shown in the figure, this embodiment introduces a condensing heat recovery constant temperature and humidity air conditioning system, including a constant temperature and humidity unit and a constant temperature and humidity chamber 14. The constant temperature and humidity unit is connected to the constant temperature and humidity chamber 14 through an air supply duct 12. An exhaust fan is installed on the constant temperature and humidity chamber, and the outlet of the exhaust fan is connected to an exhaust duct. A temperature and humidity sensor is installed on the exhaust duct. The constant temperature and humidity unit includes a housing 1, a fresh air temperature probe 1-1 arranged sequentially along the airflow direction inside the housing, a first heat exchanger 1-2, a second heat exchanger 1-3, an outlet air temperature probe 1-4, a humidifier 1-5, and a blower 1-6; and a compressor 2, a four-way valve 10, an outdoor heat exchanger 6, and an outdoor fan 7 arranged outside the housing 1. In defrost mode, the four-way valve 10 reverses, and one output of the compressor 2 is connected to the input of the compressor 2 via the reheat electric ball valve 5, the second heat exchanger 1-3, the electronic expansion valve 1-7, the first heat exchanger 1-2, and then via the four-way valve 10. The other output of the compressor 2 is connected to the input of the compressor 2 via the four-way valve 10, the condensing electric ball valve 4, the outdoor heat exchanger 6, the electronic expansion valve 1-7, the first heat exchanger 1-2, and then via the four-way valve 10.

[0040] Furthermore, in heating mode, the output of compressor 2 is connected to the input of compressor 2 via reheat electric ball valve 5, second heat exchanger 1-3, outdoor heat exchanger 6, condensing electric ball valve 4, and then via four-way valve 10. The output of compressor 2 is also connected to the input of compressor 2 via four-way valve 10, first heat exchanger 1-2, electronic expansion valve 1-7, outdoor heat exchanger 6, condensing electric ball valve 4, and then via four-way valve 10.

[0041] Optionally, a condensing pressure sensor 3 is installed on the pipeline between the output end of the compressor 2 and the four-way valve 10; an evaporating pressure sensor 9 is installed on the pipeline between the four-way valve 10 and the input end of the compressor 2; and a compressor top temperature sensor 11 and a compressor bottom temperature sensor 9 are respectively installed at both ends of the compressor 2.

[0042] Among them, the fresh air temperature probe 1-1, electronic expansion valve 1-7, temperature and humidity sensor 1-9, condensing pressure sensor 3, evaporating pressure sensor 8, compressor top temperature sensor 11, compressor bottom temperature sensor 9, condensing electric ball valve 4, reheat electric ball valve 5, and four-way valve 10 are all connected to the control system; the supply fan 1-6 and exhaust fan 1-8 are both variable frequency fans, which can adjust the supply and exhaust air volume at any time to meet the indoor pressure difference requirements; compressor 2 is a variable frequency compressor, and the output load of compressor 2 is mainly determined by the difference between the temperature detected by temperature and humidity sensor 1-8 and the target temperature, specifically a PID control method; humidifier 1-5 is an electric heating humidifier, and the output of humidifier 1-5 is mainly determined by the difference between the humidity detected by temperature and humidity sensor 1-8 and the target humidity, specifically also a PID control method.

[0043] Optionally, the adjustment range of the condensing electric ball valve 4 and the reheating electric ball valve 5 is 0-3000p. Further, during heating operation, both the reheating electric ball valve 5 and the condensing electric ball valve 4 are opened to 3000p. During defrosting operation, the four-way valve is de-energized and switched from ON to OFF, while the condensing electric ball valve 4 closes to 1000p, and the opening of the electronic expansion valve is adjusted to 180p to distribute the condensing load, with a portion used for defrosting and a portion used to maintain the indoor temperature.

[0044] Example 2:

[0045] Referring to Figure 2, based on Embodiment 1, the present invention provides a defrosting control method applicable to the above-described condensing heat recovery constant temperature and humidity air conditioning system, the method comprising:

[0046] When the air conditioning system reaches the defrosting condition as monitored, the frequency of compressor 2 is adjusted to H1;

[0047] After ensuring that the frequency of the compressor 2 is stable at H1 within the preset first time interval, the four-way valve 10 is closed to allow the four-way valve 10 to switch, and at the same time the opening of the condensing electric ball valve 4 is adjusted to 1000p and the opening of the electronic expansion valves 1-7 is adjusted to 180p, where H1 represents the preset first frequency.

[0048] After the preset second time interval, the frequency of compressor 2 is adjusted to H2, the outdoor fan 7 is turned off, and the frequencies of supply fans 1-6 and exhaust fans 15 are all adjusted to H. Here, H2 represents the preset second frequency, and H represents the defrosting frequency.

[0049] When the defrosting conditions are met, adjust the frequency of compressor 2 to H1;

[0050] After ensuring that the frequency of the compressor 2 is stable at H1 within the preset first time interval, open the four-way valve 10 to make the four-way valve 40 switch again, and at the same time adjust the opening of the condensing electric ball valve 4 back to 3000p and adjust the opening of the electronic expansion valves 1-7 back to the normal operating opening.

[0051] After the preset second time interval, the frequencies of compressor 2, blower 1-6 and exhaust fan 15 are all adjusted back to their respective normal operating frequencies, and outdoor fan 7 is turned on at the same time.

[0052] Optionally, the value range of H1 is 30Hz to 50Hz; the value range of H2 is 70Hz to 90Hz; the value range of H is 20Hz to 50Hz; and both the first time interval and the second time interval are 5 seconds.

[0053] It should be noted that the reheat electric ball valve 5 maintains an opening of 3000p whether in heating or defrosting operation.

[0054] Optionally, the conditions for reaching the end of defrosting include:

[0055] The pressure monitored by the condensing pressure sensor 3 is greater than or equal to a preset condensing pressure threshold, or the compressor top temperature is greater than or equal to a preset temperature threshold, or the defrosting time is greater than or equal to a preset time threshold; wherein, the condensing pressure threshold is preferably 3.0 MPa; the temperature threshold is preferably 95 °C; and the time threshold is preferably 10 min.

[0056] As an embodiment of the present invention, the step of determining whether the air conditioning system has reached the defrosting condition includes:

[0057] Step 1: After the compressor starts up, detect the fresh air temperature and determine whether the fresh air temperature is ≤X, where X represents the preset temperature threshold; if yes, proceed to step 2; otherwise, proceed to step 3.

[0058] Step 2: Monitor whether the hot running time of the compression mechanism is ≥Y, where Y represents the preset first time threshold. If yes, proceed to step 4; otherwise, proceed to step 1.

[0059] Step 3: Monitor whether the hot running time of the compression mechanism is ≥ Z, where Z>Y, and Z represents the preset third time threshold; if yes, proceed to step 7; if no, proceed to step 1.

[0060] Step 4: Periodically monitor the fresh air temperature, compressor frequency, and exhaust air temperature and humidity sensor temperature, and calculate the fresh air temperature change rate a1, compressor frequency change rate a2, and exhaust air temperature change rate a3 within the current cycle; calculate a based on a1 and a2: a = a1 / (a2*0.24);

[0061] Step 5: Determine if a≤0.8 and a3≤-2. If yes, proceed to step 7; otherwise, proceed to step 6.

[0062] Step 6: Determine whether the hot running time of the compression mechanism is ≥Q, where Q>Y, and Q represents the preset second time threshold; if yes, proceed to step 7; otherwise, proceed to step 4.

[0063] Step 7: Enter defrost mode.

[0064] Optionally, X is set to 12℃; Y to 40 min; Z to 120 min; and Q to 80 min. The monitoring cycle for fresh air temperature, compressor frequency, and exhaust air temperature and humidity sensor temperature is 40 seconds per cycle. See details below. Figure 3 The image shows one embodiment of the present invention for achieving the defrosting conditions.

[0065] In summary, the opening ratio of the condensing electric ball valve 4 in this embodiment of the invention is set to 3:1, which takes into account the defrosting time and indoor temperature and humidity fluctuations, and can allocate the optimal opening for the condensing load. By calculating the fresh air temperature change rate a1, the compressor frequency change rate a2, and the return air temperature change rate a3, the conditions for entering defrosting are determined, making the defrosting cycle more reasonable and avoiding false defrosting. In addition, the supply fan 1-6 and the exhaust fan 1-8 cooperate with each other to reduce the air volume and increase the supply air temperature during the defrosting process, ensuring that the pressure difference in the constant temperature and humidity room 14 remains stable. This invention solves the heat compensation required for defrosting by replacing traditional electric heating with condensing heat, which not only reduces costs but also has low energy consumption, making it suitable for widespread application.

[0066] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0067] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0068] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0069] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A defrosting control method suitable for a condensing heat recovery constant temperature and humidity air conditioning system, characterized in that, The condensation heat recovery constant temperature and humidity air conditioning system includes a constant temperature and humidity unit; the constant temperature and humidity unit includes a shell, a fresh air temperature probe, a first heat exchanger, a second heat exchanger, an outlet air temperature probe, a humidifier, a blower, a compressor, a four-way valve, an outdoor heat exchanger, and an outdoor fan arranged in sequence along the wind direction inside the shell. In defrost mode, the four-way valve reverses, and one output of the compressor is connected to the input of the compressor via the reheat electric ball valve, the second heat exchanger, the electronic expansion valve, the first heat exchanger, and then via the four-way valve. The other output of the compressor is connected to the input of the compressor via the four-way valve, the condensing electric ball valve, the outdoor heat exchanger, the electronic expansion valve, the first heat exchanger, and then via the four-way valve. The defrosting control method includes: When the air conditioning system reaches the defrosting condition as monitored, the compressor frequency is adjusted to H1, where H1 represents the preset first frequency; After ensuring that the frequency of the compressor is stable at H1 within a preset first time interval, close the four-way valve to make the four-way valve switch, and at the same time adjust the opening of the condensing electric ball valve to a preset first opening and adjust the opening of the electronic expansion valve to a preset second opening. After the preset second time interval, the compressor frequency is adjusted to H2, the outdoor fan is turned off, and the frequencies of both the supply fan and the exhaust fan are adjusted to H. Here, H2 represents the preset second frequency, and H represents the defrosting frequency. When the defrosting conditions are met, adjust the compressor frequency to H1; After ensuring that the frequency of the compressor is stable at H1 within the preset first time interval, open the four-way valve to make the four-way valve switch again, and at the same time adjust the opening of the condensing electric ball valve back to 3000p and the opening of the electronic expansion valve back to the normal operating opening. After the preset second time interval, the frequencies of the compressor, blower and exhaust fan are all adjusted back to their respective normal operating frequencies, and the outdoor fan is turned on at the same time. The steps for determining whether the air conditioning system meets the conditions for defrosting include: The compressor mechanism detects the fresh air temperature after a hot start-up. If the fresh air temperature is ≤X, then monitor whether the compressor heating operation time T satisfies T≥Y; if T≥Y is satisfied, then periodically monitor the fresh air temperature, compressor frequency, and exhaust air temperature and humidity sensor temperature, and calculate the fresh air temperature change rate a1, compressor frequency change rate a2, and exhaust air temperature change rate a3 in the current cycle respectively. Calculate a based on a1 and a2: a = a1 / (a2*0.24); where X represents the preset temperature threshold and Y represents the preset first time threshold. If a≤0.8 and a3≤-2, then directly enter defrost mode; otherwise, wait until the compressor hot running time T≥Q before entering defrost mode, where Q>Y, and Q represents the preset second time threshold. If the fresh air temperature is greater than X, the defrost mode will be entered when the compressor's hot running time is greater than or equal to Z, where Z > Y and Z represents the preset third time threshold.

2. The defrosting control method for a condensing heat recovery constant temperature and humidity air conditioning system according to claim 1, characterized in that, In heating mode, the output of the air conditioning system is connected to the input of the compressor via a reheat electric ball valve, a second heat exchanger, an outdoor heat exchanger, a condensing electric ball valve, and a four-way valve. The output of the compressor is also connected to the input of the compressor via a four-way valve, a first heat exchanger, an electronic expansion valve, an outdoor heat exchanger, a condensing electric ball valve, and a four-way valve.

3. The defrosting control method for a condensing heat recovery constant temperature and humidity air conditioning system according to claim 1, characterized in that, It also includes a constant temperature and humidity chamber, and the constant temperature and humidity unit is connected to the constant temperature and humidity chamber through an air supply duct.

4. The condensation heat recovery constant temperature and humidity air conditioning system according to claim 3, characterized in that, The constant temperature and humidity chamber is equipped with an exhaust fan, the outlet of which is connected to an exhaust duct, and a temperature and humidity sensor is installed on the exhaust duct.

5. The defrosting control method for a condensing heat recovery constant temperature and humidity air conditioning system according to claim 1, characterized in that, A condensing pressure sensor is installed on the pipeline between the output end of the compressor and the four-way valve; an evaporating pressure sensor is installed on the pipeline between the four-way valve and the input end of the compressor; and a compressor top temperature sensor and a compressor bottom temperature sensor are respectively installed at both ends of the compressor.

6. The defrosting control method for a condensing heat recovery constant temperature and humidity air conditioning system according to claim 1, characterized in that, X is set to 12℃; Y is set to 40min; Z is set to 120min; Q is set to 80min; the monitoring cycle for the fresh air temperature, compressor frequency, and exhaust air temperature and humidity sensor is 40 seconds / time.

7. The defrosting control method for a condensing heat recovery constant temperature and humidity air conditioning system according to claim 1, characterized in that, The conditions for completing the defrosting process include: The pressure detected by the condensing pressure sensor is greater than or equal to the preset condensing pressure threshold, or the compressor top temperature is greater than or equal to the preset temperature threshold, or the defrosting time is greater than or equal to the preset time threshold.

8. The defrosting control method for a condensing heat recovery constant temperature and humidity air conditioning system according to claim 1, characterized in that, The value range of H1 is 30 Hz to 50 Hz; the value range of H2 is 70 Hz to 90 Hz; the value range of H is 20 Hz to 50 Hz; the first time interval and the second time interval are both 5 seconds.

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