Series two-coupling supply system operation anti-freezing control method

Abstract

The present application relates to air conditioning technical field, in order to facilitate the freeze protection of series two supply system, provide series two supply system operation freeze control method, through the freeze protection control of series two supply system operation state water system, is divided into freeze protection control and freeze protection control, normal condition system can enter freeze protection control, protection exits after normal, ensure normal operation, abnormal condition system will enter freeze protection control, report water system freeze protection failure and cannot be restored, ensure that the system is abnormal and does not damage.In freeze protection control, different protection control methods are used according to the different system operation modes, and the control is more accurate and more energy-saving.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, specifically a method for antifreeze control of a series dual-supply system. Background Technology

[0002] Air conditioning addresses users' needs for ambient temperature, but due to factors such as the airflow from air conditioners and low floor temperatures in winter, its heating comfort is consistently inferior to that of underfloor heating. In recent years, combined cooling and heating systems have developed rapidly, integrating air conditioning cooling with underfloor heating to truly improve users' comfort experience.

[0003] Dual-source systems include three types: underfloor water / ground water, underfloor refrigerant / ground water, and underfloor refrigerant / ground refrigerant. Underfloor refrigerant / ground water systems are formed by adding a ground heating heat exchange module (including a ground-level heat exchange module with a water-refrigerant heat exchanger) or a water-refrigerant heat exchanger to a multi-split system. Because water or an aqueous solution is used as the refrigerant for underfloor heating, it is prone to freezing and expansion or clogging of water pipes in low-temperature environments, leading to system damage. Therefore, antifreeze protection is required.

[0004] Existing antifreeze protection primarily targets water freezing in the water-refrigerant heat exchanger caused by refrigerant leakage during cooling operation in parallel-connected dual-supply systems. Parallel-connected dual-supply systems treat the water-refrigerant heat exchanger as a special indoor unit connected in parallel. During cooling and defrosting, the refrigerant can bypass the heat exchanger by closing its inlet and outlet valves to prevent refrigerant flow; therefore, only valve leakage causing water freezing is considered. However, in series-connected dual-supply systems, the refrigerant flows through the indoor unit and the water-refrigerant heat exchanger in series, always passing through the heat exchanger. Therefore, the antifreeze control method for parallel-connected dual-supply systems is completely different from that for series-connected systems, and currently, the industry lacks antifreeze protection specifically for series-connected dual-supply systems. Summary of the Invention

[0005] To facilitate the anti-freezing protection of a series-connected dual-supply system, this application provides an anti-freezing control method for the operation of a series-connected dual-supply system.

[0006] The technical solution adopted by the present invention to solve the above problems is:

[0007] The anti-freezing control method for a series-connected dual-supply system includes:

[0008] Step 1: Obtain the circulating water temperature Tf_w, refrigerant temperature Tf_r, and outdoor ambient temperature Tor of the water-fluorine heat exchanger;

[0009] Step 2: If the circulating water temperature Tf_w ≤ preset value Tf_w_0 or the refrigerant temperature Tf_r ≤ preset value Tf_r_0, then perform antifreeze fault control;

[0010] If not, different antifreeze protection controls will be activated based on the different operating modes:

[0011] When the operating mode is the first operating mode, the first antifreeze control is activated;

[0012] When the operating mode is air conditioning heating mode, the second anti-freeze control is activated;

[0013] When the operating mode is radiant heating, the third antifreeze control is activated.

[0014] Furthermore, the anti-freeze fault control specifically involves: the heat exchanger unit's water pump being forced to run, while the compressor, indoor motor, and outdoor motor are stopped.

[0015] Furthermore, the first operating mode is: air conditioning dehumidification operation, air conditioning cooling operation, or ground radiant cooling operation.

[0016] Furthermore, the first antifreeze control specifically means that when the refrigerant temperature Tf_r ≤ preset value Tf_r_1, the water system enters antifreeze protection and the compressor no longer increases its frequency;

[0017] When the refrigerant temperature Tf_r ≤ preset value Tf_r_2, the compressor reduces its frequency; when the refrigerant temperature Tf_r ≥ preset value Tf_r_4, the compressor stops reducing its frequency; when the refrigerant temperature Tf_r ≤ preset value Tf_r_3, the compressor stops running.

[0018] When the refrigerant temperature Tf_r ≥ preset value Tf_r_5, the system exits anti-freeze protection;

[0019] Among them, Tf_r_3 < Tf_r_2 < Tf_r_1, Tf_r_2 < Tf_r_4, Tf_r_1 < Tf_r_5.

[0020] Furthermore, the second antifreeze control specifically involves: determining whether defrosting is required; if so, performing defrosting control; if not, starting the water pump when the outdoor ambient temperature Tor ≤ preset value Tor_0 and the water pump stop duration tpu_stop ≥ preset value tpu_stop_0, and stopping the water pump when the circulating water temperature Tf_w ≥ preset value Tf_w_1 and the duration tw_0.

[0021] Furthermore, the third antifreeze control specifically involves: determining whether defrosting is required; if so, performing defrosting control; otherwise, ending the process.

[0022] Furthermore, the defrosting control specifically involves: turning on the water pump, turning off the indoor fan, continuing to heat the outdoor unit, then detecting the circulating water temperature Tf_w. When Tf_w ≥ Tf_w_2 and lasts for tw_1 minutes, defrosting begins. After defrosting is completed, the unit switches to heating operation, turns off the water pump, and turns on the indoor fan.

[0023] Furthermore, the preset value Tf_w_0 is between 0 and 6℃, and the preset value Tf_r_0 is between -3 and 3℃.

[0024] Furthermore, the preset value Tor_0 is between -2 and 5℃, the preset value Tf_w_1 is between 5 and 20℃, the preset time tpu_stop_0 is between 10 and 120 minutes, and the preset time tw_0 is between 0 and 10 minutes.

[0025] Furthermore, the circulating water temperature Tf_w is the minimum value of the water pipe inlet temperature, water pipe outlet temperature, water pipe inlet temperature, and water pipe outlet temperature of the water-fluoride heat exchange module, or the average value of the water pipe inlet temperature and water pipe outlet temperature.

[0026] The refrigerant temperature Tf_r is the minimum or average of the inlet and outlet temperatures of the fluorine pipe in the water-fluorine heat exchange module.

[0027] The advantages of this invention compared to existing technologies are as follows: This invention divides the anti-freezing control of the water system in a series-connected dual-supply system into anti-freezing fault control and anti-freezing protection control. Under normal circumstances, the system can enter anti-freezing protection control, and returns to normal after protection exits, ensuring normal system operation. Under abnormal circumstances, the system will enter anti-freezing fault control, reporting an unrecoverable anti-freezing fault in the water system, ensuring that the system is not damaged in abnormal situations. Different protection control methods are adopted according to different system operating modes during anti-freezing protection control, resulting in more precise and energy-efficient control. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a series-connected dual-supply system.

[0029] Figure 2 Flowchart of the antifreeze control method for a series-connected dual-supply system;

[0030] Figure 3 This is the flowchart for the first antifreeze control.

[0031] Figure 4 This is the second antifreeze control flowchart;

[0032] Figure 5 This is the flowchart for the third antifreeze control.

[0033] Figure 6 This is a flowchart of the defrosting control process.

[0034] Figure reference numerals: 1-Outdoor unit, 2-Indoor unit, 3-Water-refrigerant heat exchanger unit, 4-Water pipe, 5-Manifold, 6-Underfloor heating coil, 7-Refrigerant pipe, 101-Outdoor ambient temperature sensor, 301-Water-gas heat exchanger, 302-Water pump, 311-Water pipe outlet sensor, 312-Water pipe inlet sensor, 321-Refrigerant pipe outlet sensor, 322-Refrigerant pipe inlet sensor, 401-Water pipe freezer-prone area sensor. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] like Figure 1 As shown, the series dual-supply system consists of an outdoor unit 1, an indoor unit 2, a water-fluorine heat exchanger unit 3, a manifold 5, and underfloor heating coils 6 connected in series via water pipes 4 and refrigerant pipes 7. The water-fluorine heat exchanger unit 3 is equipped with a water-fluorine heat exchanger 301, a water pump 302, a water pipe outlet sensor 311, a water pipe inlet sensor 312, a refrigerant pipe outlet sensor 321, and a refrigerant pipe inlet sensor 322. The outdoor unit 1 is equipped with an outdoor ambient temperature sensor 101, and a water pipe freezing point sensor 401 is installed at the freezing point of the water pipe.

[0037] like Figure 2 As shown, the anti-freezing control method for a series-connected dual-supply system includes:

[0038] Step 1: Obtain the circulating water temperature Tf_w, refrigerant temperature Tf_r, and outdoor ambient temperature Tor of the water-fluorine heat exchanger;

[0039] Step 2: If the circulating water temperature Tf_w ≤ preset value Tf_w_0 or the refrigerant temperature Tf_r ≤ preset value Tf_r_0, then antifreeze fault control will be implemented: the heat exchanger unit water pump will be forced to run, the compressor, indoor motor, and outdoor motor will stop running, and the system will display a water system antifreeze fault report; antifreeze fault control is used to control and protect the system in case of faults or abnormal conditions, such as the four-way valve not switching during heating mode operation, water system blockage preventing circulation, or insufficient flow, etc., and is effective in any operating mode; if the system cannot automatically recover under antifreeze fault control, it can also report an antifreeze fault; the preset value Tf_w_0 is between 0 and 6℃, such as 2℃, and Tf_r_0 is between -3 and 3℃, such as 0℃.

[0040] For example, if the air conditioner is operating in heating mode but the four-way valve fails to switch due to lack of power or jamming, the dual-supply system is actually operating in cooling mode. The refrigerant temperature in the water-refrigerant heat exchanger drops rapidly. When it falls below the preset value Tf_r_0, the dual-supply system activates the water pump, shuts down the compressor, indoor motor, and outdoor motor, and displays a water system anti-freeze fault report. The compressor shutdown cuts off the power for refrigerant temperature reduction, while the water pump operation utilizes underfloor heating water and stored indoor heat to heat the water-refrigerant heat exchanger. The anti-freeze fault report informs the user of the system malfunction, rendering it unusable and requiring repair. The system cannot automatically recover to prevent frequent system starts and potential damage.

[0041] If not, different antifreeze protection controls will be entered according to different operating modes. The antifreeze protection control is used for water system protection control during normal operation of the dual-supply system. No fault will be reported. After entering the protection mode, the system will automatically exit the protection mode and the system will resume the start-up state when the conditions are met.

[0042] Specifically: when the operating mode is the first operating mode, the first anti-freeze control is activated, such as... Figure 3 As shown: When the refrigerant temperature Tf_r ≤ preset value Tf_r_1, the water system enters anti-freeze protection, and the compressor no longer increases frequency;

[0043] When the refrigerant temperature Tf_r ≤ preset value Tf_r_2, the compressor reduces its frequency; when the refrigerant temperature Tf_r ≥ preset value Tf_r_4, the compressor stops reducing its frequency; when the refrigerant temperature Tf_r ≤ preset value Tf_r_3, the compressor stops running.

[0044] When the refrigerant temperature Tf_r ≥ preset value Tf_r_5, the system exits anti-freeze protection; where Tf_r_3 < Tf_r_2 < Tf_r_1, Tf_r_2 < Tf_r_4, and Tf_r_1 < Tf_r_5.

[0045] The first operating mode is: air conditioning dehumidification operation, air conditioning cooling operation, or ground radiant cooling operation.

[0046] When the operating mode is air conditioning heating mode, the second anti-freeze control is activated, such as... Figure 4 As shown: Determine whether defrosting is needed. If so, defrosting control is performed; otherwise, the water pump is started when the outdoor ambient temperature Tor ≤ preset value Tor_0 and the water pump stop duration tpu_stop ≥ preset value tpu_stop_0. The water pump is stopped when the circulating water temperature Tf_w ≥ preset value Tf_w_1 and the duration tw_0.

[0047] The preset values ​​are: Tor_0 between -2 and 5℃, Tf_w_1 between 5 and 20℃, tpu_stop_0 between 10 and 120 minutes, and tw_0 between 0 and 10 minutes. For example... Figure 4 As shown, when operating in air conditioning heating mode, the water system is not running. In low-temperature environments, exposed outdoor water pipes or underfloor heating pipes in unheated rooms may freeze (the indoor air conditioning unit may be installed in one room). The water system is heated by periodically starting the water pump to prevent freezing. To save energy, the preset value for the water pump stop duration can be set in segments based on the outdoor ambient temperature Tor or calculated using a fitting formula, thereby minimizing the water pump running time while ensuring no freezing.

[0048] When the operating mode is radiant heating, it enters the third anti-freeze control, such as... Figure 5 As shown, determine whether defrosting is needed. If so, defrosting control is initiated; otherwise, the process ends.

[0049] like Figure 6 As shown, the water-refrigerant heat exchanger is at a low temperature during defrosting. To prevent freezing, the water temperature is heated before defrosting, and the water pump operates during defrosting, thus achieving defrosting by utilizing the heat stored in the water system. In the ground radiant heating mode, theoretically, water temperature heating is not required before the defrosting process. However, to unify the defrosting control with air conditioning heating, a water temperature heating and detection process is added. If this process is separated from the defrosting control of the air conditioning heating mode, the pre-defrosting heating and circulating water temperature judgment process can be eliminated.

[0050] Specifically, the first operating mode is: air conditioning dehumidification operation, air conditioning cooling operation, or floor radiant cooling operation. The value of the same preset value in each operating mode can be set according to actual needs and can vary. The preset value Tf_r_3 is between -2 and 6℃, such as 1℃; Tf_r_2 is between 0 and 8℃, such as 4℃; Tf_r_1 is between 2 and 10℃, such as 7℃; Tf_r_4 is between 2 and 10℃, such as 6℃; and Tf_r_5 is between 4 and 15℃, such as 9℃. Figure 3 The anti-freeze protection control is divided into three levels: the first level is compressor frequency limit protection (frequency limiting protection), the second level is compressor frequency reduction protection, and the third level is compressor stop protection. Through the three-level protection, the Tf_r temperature is ensured not to be too low, and the compressor frequency can operate stably within a wide range, so as to achieve a balance between reliable protection and system capacity.

[0051] The circulating water temperature Tf_w is the minimum, average, or either of the inlet and outlet temperatures of the water pipe in the water-fluoride heat exchange module; the refrigerant temperature Tf_r is the minimum, average, or either of the inlet and outlet temperatures of the refrigerant pipe in the water-fluoride heat exchange module.

Claims

1. A method for preventing freezing in a series two-coupled heat supply system operation, characterized by, The method comprises the following steps: Step 1, obtaining the circulating water temperature Tf_w, the refrigerant temperature Tf_r and the outdoor environment temperature Tor of a water-fluorine heat exchanger; Step 2, if the circulating water temperature Tf_w is less than or equal to a preset value Tf_w_0 or the refrigerant temperature Tf_r is less than or equal to a preset value Tf_r_0, anti-freezing fault control is performed; If not, different anti-freezing protection controls are entered according to different operation modes: When the operation mode is a first operation mode, a first anti-freezing control is performed; the first anti-freezing control is specifically as follows: when the refrigerant temperature Tf_r is less than or equal to a preset value Tf_r_1, the water system enters anti-freezing protection, and the compressor no longer increases the frequency; When the refrigerant temperature Tf_r is less than or equal to a preset value Tf_r_2, the compressor decreases the frequency; when the refrigerant temperature Tf_r is greater than or equal to a preset value Tf_r_4, the compressor stops decreasing the frequency; when the refrigerant temperature Tf_r is less than or equal to a preset value Tf_r_3, the compressor stops running; When the refrigerant temperature Tf_r is greater than or equal to a preset value Tf_r_5, the system exits the anti-freezing protection; Wherein, Tf_r_3 < Tf_r_2 < Tf_r_1, Tf_r_2 < Tf_r_4, and Tf_r_1 < Tf_r_5; When the operation mode is an air conditioning heating mode, a second anti-freezing control is performed; the second anti-freezing control is specifically as follows: whether defrosting is judged, if yes, defrosting control is performed; if not, when the outdoor environment temperature Tor is less than or equal to a preset value Tor_0 and the water pump stop duration tpu_stop is greater than or equal to a preset value tpu_stop_0, the water pump is started to run; when the circulating water temperature Tf_w is greater than or equal to a preset value Tf_w_1 and the duration tw_0, the water pump is stopped to run; When the operation mode is a radiant heating mode, a third anti-freezing control is performed; the third anti-freezing control is specifically as follows: whether defrosting is judged, if yes, defrosting control is performed; if not, the process is ended.

2. The series type two-heat-supply-system operation anti-freezing control method according to claim 1, characterized by The anti-freezing fault control is specifically as follows: the heat exchanger unit water pump is forced to run, and the compressor, the indoor motor and the outdoor motor stop running.

3. The anti-freezing control method for the series two-supply system operation according to claim 1, characterized by, The first operation mode is air conditioning dehumidification operation, air conditioning refrigeration operation or ground radiant refrigeration operation.

4. The anti-freezing control method for the series two-supply system operation according to claim 1, characterized by, The defrosting control is specifically as follows: the water pump is started, the indoor fan is stopped, the outdoor unit continues to heat, and the circulating water temperature Tf_w is detected again; when Tf_w is greater than or equal to Tf_w_2 and the duration tw_1 is greater than or equal to 1 minute, defrosting is started; after defrosting is finished, heating operation is started again, the water pump is stopped, and the indoor fan is started.

5. The anti-freezing control method for the series type two-union supply system operation according to claim 4, characterized in that, The preset value Tf_w_0 is between 0 and 6 ℃, and the preset value Tf_r_0 is between -3 and 3 ℃.

6. The anti-freezing control method for the series type two-union supply system operation according to claim 4, characterized in that, The preset value Tor_0 is between -2 and 5 ℃, the preset value Tf_w_1 is between 5 and 20 ℃, the preset time tpu_stop_0 is between 10 and 120 min, and the preset time tw_0 is between 0 and 10 min.

7. The method according to any one of claims 1 to 6, wherein the method is a freeze prevention control method for a series two-supply system operation. The circulating water temperature Tf_w is the water pipe inlet temperature, the water pipe outlet temperature, the minimum value of the water pipe inlet temperature and the water pipe outlet temperature or the average value of the water pipe inlet temperature and the water pipe outlet temperature of the water-fluorine heat exchange module; The refrigerant temperature Tf_r is the fluorine pipe inlet temperature, the fluorine pipe outlet temperature, the minimum value of the fluorine pipe inlet temperature and the fluorine pipe outlet temperature or the average value of the fluorine pipe inlet temperature and the fluorine pipe outlet temperature of the water-fluorine heat exchange module.

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