A regulating cooling system and control method for a chilled water air conditioning unit

Abstract

This invention belongs to the field of electrical equipment cooling technology, specifically providing a regulating cooling system and control method for a chilled water air conditioning unit. It includes an isolation electric valve installed on the chilled water return pipe of the chilled water air conditioning unit; an air cooler inlet pipe and an air cooler outlet pipe connected to the chilled water return pipe and respectively positioned upstream and downstream of the isolation electric valve; the air cooler inlet pipe and air cooler outlet pipe connected to the inlet and outlet ends of the air cooler, respectively; and inlet electric valves and outlet electric valves respectively installed on the air cooler inlet pipe and outlet pipe. This system, installed on the return water pipe of the chilled water air conditioning unit, utilizes natural cold source cooling technology. It can replace the operation of the air conditioning unit in winter, avoiding the problem of low cooling efficiency when the air conditioning unit operates at low temperatures, significantly shortening the air conditioning unit's operating time, extending its service life, and providing certain energy-saving benefits.

Description

Technical Field

[0001] This invention belongs to the field of electrical equipment cooling technology, specifically, it relates to a regulating cooling system and control method for a chilled water air conditioning unit. Background Technology

[0002] In locations with numerous and concentrated electrical equipment, such as power plants, power transmission and transformation stations, and large data centers, air conditioning systems are needed year-round to cool the equipment rooms due to the high heat generated by these devices. Some of these locations use chilled water air conditioning units, which operate ideally in cooling mode with an ambient dry-bulb temperature of 18-43℃. In these locations, chilled water air conditioning units are also necessary for cooling the equipment rooms during the low temperatures of winter. However, in most parts of my country, the ambient dry-bulb temperature in winter is below 10℃, far lower than the ideal operating conditions for chilled water air conditioning units. Prolonged operation in low-temperature environments causes significant damage to chilled water air conditioning units, severely impacting the lifespan of key components and hindering stable equipment operation. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a regulating cooling system and control method for a chilled water air conditioning unit. It is installed on the return water pipe of the chilled water air conditioning unit and uses natural cold source cooling technology. It can replace the operation of the air conditioning unit in winter, avoid the problem of low cooling efficiency of the air conditioning unit under low temperature conditions, and can significantly shorten the operation time of the air conditioning unit, extend its service life, and have certain energy-saving benefits.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a regulating cooling system for a chilled water air conditioning unit, including an isolation electric valve installed on the chilled water return pipe of the chilled water air conditioning unit, an air cooler inlet pipe and an air cooler outlet pipe connected to the chilled water return pipe and respectively installed upstream and downstream of the isolation electric valve, the air cooler inlet pipe and the air cooler outlet pipe being connected to the inlet end and outlet end of the air cooler respectively, and an inlet electric valve and an outlet electric valve being respectively installed on the air cooler inlet pipe and the air cooler outlet pipe.

[0005] In a preferred embodiment, an air thermometer is also included, which is installed outdoors in the external environment, and an outlet water thermometer is installed on the outlet water pipe of the air cooler.

[0006] In the preferred embodiment, a PLC control cabinet is included, and an air thermometer and an outlet water thermometer are electrically connected to the PLC control cabinet. The PLC control cabinet is used to control the on / off state of the isolation electric valve, the inlet electric valve, and the outlet electric valve, as well as the start / stop of the air cooler and the chilled water air conditioning unit.

[0007] In a preferred embodiment, the cooling fan of the air cooler is a single variable frequency fan or multiple variable frequency fans connected in parallel.

[0008] The present invention also provides a control method for regulating the cooling system of a chilled water air conditioning unit, including the following modes:

[0009] 1) Winter air cooler natural cooling mode: When the ambient temperature T is less than or equal to the air cooler outlet water temperature set value T1, the air cooler enters the winter air cooler natural cooling mode.

[0010] 2) Transitional season air cooler and chilled water air conditioning unit mixed cooling mode: When the ambient temperature T is higher than the air cooler outlet water temperature setpoint T1 and lower than the chilled water air conditioning unit return water temperature setpoint T2, the air cooler and chilled water air conditioning unit mixed cooling mode is entered during the transitional season.

[0011] 3) Summer chilled water air conditioning unit cooling mode: When the ambient temperature T is greater than or equal to the set value T2 of the return water temperature of the chilled water air conditioning unit, the chilled water air conditioning unit enters the summer chilled water air conditioning unit cooling mode.

[0012] In the preferred embodiment, when the air cooler is in natural cooling mode during winter, the inlet and outlet electric valves are open, the isolation electric valve is closed, the air cooler is put into operation, and the chilled water air conditioning unit is stopped. The valve control method and the air cooler control method are as follows:

[0013] 1) Valve control method

[0014] The inlet and outlet electric valves are open, and the isolation electric valve is closed.

[0015] 2) Control method for cooling fans of air coolers

[0016] All cooling fans of the air cooler are variable frequency fans. The operating frequency is adjusted according to the feedback data of the air cooler outlet temperature sensor to keep the air cooler outlet water temperature stable within the range of the air cooler outlet water temperature set value T1.

[0017] The air cooler's cooling fan has the following five automatic modes:

[0018] a. Full Start Mode: When the air cooler outlet water temperature is greater than the air cooler outlet water temperature setpoint T1+, the air cooler's cooling fans enter the full start mode, and all cooling fans are turned on and run at the maximum frequency.

[0019] b. Full Stop Mode: When the air cooler outlet water temperature is less than the air cooler outlet water temperature setpoint T1 - full start operation hysteresis, the air cooler cooling fans enter the full stop mode, and all cooling fans are turned off and on.

[0020] c. Acceleration mode: when the air cooler outlet water temperature setpoint T1 + frequency converter operation hysteresis < air cooler outlet water temperature < air cooler outlet water temperature setpoint T1 + full start operation hysteresis, the air cooler cooling fan enters acceleration mode and the cooling fan starts at the minimum frequency of the frequency converter fan.

[0021] The variable frequency fan accelerates the cooling fan by using the acceleration speed as the time unit and the frequency operation hysteresis as the unit until all cooling fans are running at full frequency.

[0022] d. Deceleration mode: when the air cooler outlet water temperature setpoint T1 - frequency converter action hysteresis > air cooler outlet water temperature > air cooler outlet water temperature setpoint T1 - full start action hysteresis, the air cooler cooling fan enters the deceleration mode. The cooling fan is decelerated in terms of deceleration action speed as the time and frequency action hysteresis as the unit, until all cooling fans are running at the minimum frequency.

[0023] e. Idle mode: when the air cooler outlet water temperature setpoint T1 - frequency converter hysteresis < air cooler outlet water temperature < air cooler outlet water temperature setpoint T1 + frequency converter hysteresis, the air cooler's cooling fan enters idle mode and runs in the state before entering this mode.

[0024] In the preferred embodiment, when the air cooler and the chilled water air conditioning unit are in mixed cooling mode during the transition season, the inlet electric valve and the outlet electric valve are opened, the isolation electric valve is closed, the air cooler is put into operation, and the chilled water air conditioning unit is put into operation.

[0025] In the preferred embodiment, when the chilled water air conditioning unit is in cooling mode during summer, the inlet and outlet electric valves are closed, the isolation electric valve is opened, the air cooler stops operating, and the chilled water air conditioning unit is put into operation.

[0026] This invention provides a regulating cooling system and control method for water-cooled air conditioning units, used to replace water-cooled air conditioning units for cooling operation in winter. When the ambient temperature is low in winter, an air cooler is used instead of the air conditioning unit by switching the operating mode, using the cold ambient air as a natural cold source to cool the electrical equipment room, thereby achieving energy saving. This avoids the problem of low cooling efficiency of air conditioning units under low-temperature operating conditions, significantly shortens the operating time of air conditioning units, extends their service life, and has certain energy-saving benefits. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0028] Figure 1 This is a schematic diagram of the structure of the present invention installed in the original chilled water air conditioning unit refrigeration system;

[0029] Figure 2 This is the control logic diagram for this side;

[0030] In the diagram: 1. Air cooler; 2. Cooling fan; 3. Inlet electric valve; 4. Outlet electric valve; 5. Isolation electric valve; 6. Air cooler inlet pipe; 7. Air cooler outlet pipe; 8. PLC control cabinet; 9. Air thermometer; 10. Outlet water thermometer; 11. Chiller unit; 12. Chilled water circulation pump; 13. Terminal equipment of chiller unit; 14. Chilled water supply pipe; 15. Chilled water return pipe. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0032] like Figure 1 As shown, the existing chilled water air conditioning unit refrigeration system includes a chilled water air conditioning unit 11. The chilled water air conditioning unit 11 is connected to the chilled water air conditioning unit terminal equipment 13 through a chilled water supply pipe 14, a chilled water circulation pump 12, and a chilled water return pipe 15. A chilled water return water thermometer is installed on the chilled water return water pipe 15 to facilitate the measurement of the return water temperature of the chilled water air conditioning unit.

[0033] Based on the existing chilled water air conditioning unit refrigeration system, a regulating cooling system for the chilled water air conditioning unit is added, see... Figure 1 The structural diagram within the dashed box includes an isolation electric valve 5 installed on the chilled water return pipe of the chilled water air conditioning unit, an air cooler inlet pipe 6 and an air cooler outlet pipe 7 connected to the chilled water return pipe 15 and respectively installed upstream and downstream of the isolation electric valve 5, an air cooler inlet pipe 6 and an air cooler outlet pipe 7 connected to the inlet and outlet ends of the air cooler 1 respectively, and an inlet electric valve 3 and an outlet electric valve 4 respectively installed on the air cooler inlet pipe 6 and the air cooler outlet pipe 7.

[0034] The air cooler 1 is equipped with a cooling fan 2 at the top. The cooling fan 2 of the air cooler 1 is composed of a single variable frequency fan or multiple variable frequency fans connected in parallel.

[0035] It also includes an air thermometer 9, which is set near the chilled water air conditioning unit 11 and is placed outdoors to monitor the ambient temperature. The air cooler outlet pipe 7 is equipped with an outlet water thermometer 10, which is used to measure the outlet water temperature after the air cooler 1 has been cooled.

[0036] The system includes a PLC control cabinet 8, an air thermometer 9, and an outlet water thermometer 10 which are electrically connected to the PLC control cabinet 8. The PLC control cabinet 8 is used to control the opening and closing of the isolation electric valve 5, the inlet electric valve 3, and the outlet electric valve 4, as well as the opening and closing of the air cooler 1 and the chilled water air conditioning unit 11.

[0037] Air thermometer 9 measures the ambient temperature T, where T is a variable.

[0038] The outlet water thermometer 10 measures the outlet water temperature of the air cooler. The set value of the outlet water temperature of the air cooler is T1, which is a fixed value.

[0039] The return water thermometer of the chilled water air conditioning unit measures the return water temperature of the chilled water air conditioning unit. The set value of the return water temperature of the chilled water air conditioning unit is T2, which is a fixed value.

[0040] In this embodiment, under normal operating conditions, T1 < T2.

[0041] A control method for regulating the cooling system of a chilled water air conditioning unit includes the following modes:

[0042] (1) Natural cooling mode of air cooler in winter

[0043] When the ambient temperature T is less than or equal to the air cooler outlet water temperature setpoint T1, the inlet electric valve 3 opens, the outlet electric valve 4 opens, the isolation electric valve 5 closes, the air cooler 1 starts to run, the cooling fan 2 starts to run in variable frequency mode, and the chilled water air conditioning unit 11 stops running.

[0044] (2) Mixed cooling of air coolers and chilled water air conditioning units during the transitional season

[0045] When the ambient temperature T is higher than the air cooler outlet water temperature setpoint T1 and lower than the chilled water air conditioning unit return water temperature setpoint T2, the inlet electric valve 3 opens, the outlet electric valve 4 opens, the isolation electric valve 5 closes, the air cooler 1 is put into operation, the cooling fan 2 is put into full-frequency operation, and the chilled water air conditioning unit 11 is put into operation.

[0046] (3) Summer cooling of water-cooled air conditioning units

[0047] When the ambient temperature T is greater than or equal to the set value T2 of the return water temperature of the chilled water air conditioning unit, the inlet electric valve 3 is closed, the outlet electric valve 4 is closed, the isolation electric valve 5 is opened, the air cooler 1 stops running, the cooling fan 2 stops running, and the chilled water air conditioning unit 11 is put into operation.

[0048] The air cooler outlet water temperature setpoint T1 refers to the critical temperature value at which the air cooler can provide sufficient cooling capacity to the central air conditioning system when the ambient temperature T=T1 and the air cooler is operating at full frequency.

[0049] The return water temperature setpoint T2 of the chilled water air conditioning unit refers to the starting condition of the compressor when the chilled water air conditioning unit is running normally in cooling mode. When the return water temperature of the chilled water air conditioning unit is greater than the setpoint T2, the compressor of the unit starts and starts to operate in cooling mode.

[0050] In this embodiment, under normal operating conditions, T1 < T2.

[0051] This invention can achieve a fully automatic composite operation mode of "natural cooling of air cooler in winter + mixed cooling of air cooler and air-cooled unit in transitional season + cooling of air-cooled unit in summer" according to the temperature change of the operating environment of the chilled water air conditioning unit. It can also automatically adjust the operating frequency of air cooler according to the system operating conditions to achieve energy saving.

[0052] like Figure 2 As shown in the figure, this embodiment provides a detailed description of a control method for regulating the cooling system of a chilled water air conditioning unit:

[0053] (1) Natural cooling mode of air cooler in winter (when T≤T1)

[0054] ① Valve control methods

[0055] The inlet electric valve 3 is opened, the outlet electric valve 4 is opened, and the isolation electric valve 5 is closed.

[0056] ② Control method for air cooler cooling fan

[0057] All cooling fans of the air cooler are variable frequency fans. The operating frequency is automatically adjusted according to the feedback data of the air cooler outlet temperature sensor to keep the air cooler outlet water temperature stable within the range of the air cooler outlet water temperature set value T1.

[0058] The point of data collection and control is the outlet water temperature of the air cooler.

[0059] Set the setting value:

[0060] a. The air cooler outlet water temperature setpoint T1 (R / W) is determined based on the specific application case;

[0061] b. Variable frequency drive hysteresis (R / W), recommended setting is 1℃;

[0062] c. Increase motion speed (R / W), recommended setting: 3Hz / S;

[0063] d. Deceleration speed (R / W), recommended setting: 5Hz / S;

[0064] e. Frequency hysteresis (R / W), recommended setting: 1Hz;

[0065] f. Full start hysteresis (R / W), recommended setting: 2℃;

[0066] g. Minimum frequency (R / W) of variable frequency fan, recommended setting: 10Hz;

[0067] Note: Full start hysteresis > Variable frequency drive hysteresis.

[0068] The cooling fan has the following five automatic modes:

[0069] a. Full Start Mode;

[0070] b. Full Stop Mode;

[0071] c. Acceleration Mode;

[0072] d. Deceleration mode;

[0073] e. Idle mode.

[0074] Automatic mode switching logic for cooling fans:

[0075] a. Full start mode: Air cooler outlet water temperature > air cooler outlet water temperature setpoint T1 + full start for hysteresis;

[0076] b. Full Stop Mode: Air cooler outlet water temperature < air cooler outlet water temperature setpoint T1 - Full Start Hysteresis;

[0077] c. Acceleration mode: Air cooler outlet water temperature setpoint T1 + frequency converter hysteresis < air cooler outlet water temperature < air cooler outlet water temperature setpoint T1 + full start hysteresis;

[0078] d. Deceleration mode: Air cooler outlet water temperature setpoint T1 - frequency converter hysteresis > air cooler outlet water temperature > air cooler outlet water temperature setpoint T1 - full start hysteresis;

[0079] e. Idle mode: Air cooler outlet water temperature setpoint T1 - frequency converter hysteresis < air cooler outlet water temperature < air cooler outlet water temperature setpoint T1 + frequency converter hysteresis.

[0080] Automatic control logic for cooling fan mode:

[0081] a. Full Start Mode

[0082] All variable frequency fans are turned on and running at maximum frequency.

[0083] b. Full Stop Mode

[0084] All variable frequency fans were switched off and on.

[0085] c. Acceleration Mode

[0086] The fan starts at the minimum frequency required for a variable frequency fan.

[0087] The variable frequency fan accelerates by using the speed of acceleration as the time unit and the frequency operation hysteresis as the unit, until all fans are running at full frequency.

[0088] d. Deceleration mode

[0089] The variable frequency fan reduces its speed by using the deceleration action speed as the time and the frequency action hysteresis as the unit, until all fans are running at their minimum frequency.

[0090] e. Idle mode

[0091] The fan operates in the state it was in before entering this mode.

[0092] (2) Mixed cooling mode of air cooler and chilled water air conditioning unit during the transition season (when T1 < T < T2)

[0093] ① Valve control methods

[0094] The inlet electric valve 3 is opened, the outlet electric valve 4 is opened, and the isolation electric valve 5 is closed.

[0095] ② Control methods for air coolers and chilled water air conditioning units

[0096] All cooling fans of the air cooler operate at full frequency, and the chilled water air conditioning unit operates automatically according to the original central air conditioning system's cooling mode. At this time, the chilled water air conditioning unit automatically operates by controlling the return water temperature to stabilize within the range of the chilled water air conditioning unit's return water temperature setpoint T2.

[0097] (3) Cooling mode of chilled water air conditioning unit in summer (when T≥T2)

[0098] ① Valve control methods

[0099] The inlet electric valve 3 is closed, the outlet electric valve 4 is closed, and the isolation electric valve 5 is open.

[0100] ② Control methods for air coolers and chilled water air conditioning units

[0101] When the air cooler 1 stops operating, the chilled water air conditioning unit 11 automatically operates according to the original central air conditioning system's cooling mode. At this time, the chilled water air conditioning unit automatically operates by controlling the return water temperature to stabilize within the range of the chilled water air conditioning unit's return water temperature setpoint T2.

[0102] This control method is implemented through PLC programming control. The electrical control equipment of the entire control system includes, but is not limited to: PLC programmable controller, frequency converter, low-voltage components, HMI, air thermometer, water thermometer, etc. The control logic of this method is attached. Figure 2 .

[0103] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control method for regulating the cooling system of a chilled water air conditioning unit, characterized in that, The regulating cooling system for the chilled water air conditioning unit includes an isolation electric valve installed on the chilled water return pipe of the chilled water air conditioning unit, an air cooler inlet pipe and an air cooler outlet pipe connected to the chilled water return pipe and respectively installed upstream and downstream of the isolation electric valve, an air cooler inlet pipe and an air cooler outlet pipe respectively connected to the inlet end and outlet end of the air cooler, and an inlet electric valve and an outlet electric valve respectively installed on the air cooler inlet pipe and the air cooler outlet pipe; Includes the following modes: Winter air cooler natural cooling mode: When the ambient temperature T is less than or equal to the air cooler outlet water temperature set value T1, the air cooler enters the winter air cooler natural cooling mode. When the air cooler is in natural cooling mode during winter, the inlet and outlet electric valves are open, the isolation electric valve is closed, the air cooler is put into operation, and the chilled water air conditioning unit stops operating. The valve control method and air cooler control method are as follows: 1) Valve control method The inlet and outlet electric valves are open, and the isolation electric valve is closed. 2) Control method for cooling fans of air coolers All cooling fans of the air cooler are variable frequency fans. The operating frequency is adjusted according to the feedback data of the air cooler outlet temperature sensor to keep the air cooler outlet water temperature stable within the range of the air cooler outlet water temperature set value T1. The air cooler's cooling fan has the following five automatic modes: a. Full Start Mode: When the air cooler outlet water temperature is greater than the air cooler outlet water temperature setpoint T1+, the air cooler's cooling fans enter the full start mode, and all cooling fans are turned on and run at the maximum frequency. b. Full Stop Mode: When the air cooler outlet water temperature is less than the air cooler outlet water temperature setpoint T1 - full start operation hysteresis, the air cooler cooling fans enter the full stop mode, and all cooling fans are turned off and on. c. Acceleration mode: when the air cooler outlet water temperature setpoint T1 + frequency converter operation hysteresis < air cooler outlet water temperature < air cooler outlet water temperature setpoint T1 + full start operation hysteresis, the air cooler cooling fan enters acceleration mode and the cooling fan starts at the minimum frequency of the frequency converter fan. The variable frequency fan accelerates the cooling fan by using the acceleration speed as the time unit and the frequency operation hysteresis as the unit until all cooling fans are running at full frequency. d. Deceleration mode: when the air cooler outlet water temperature setpoint T1 - frequency converter action hysteresis > air cooler outlet water temperature > air cooler outlet water temperature setpoint T1 - full start action hysteresis, the air cooler cooling fan enters the deceleration mode. The cooling fan is decelerated in terms of deceleration action speed as the time and frequency action hysteresis as the unit, until all cooling fans are running at the minimum frequency. e. Idle mode: when the air cooler outlet water temperature setpoint T1 - frequency converter hysteresis < air cooler outlet water temperature < air cooler outlet water temperature setpoint T1 + frequency converter hysteresis, the air cooler's cooling fan enters idle mode and runs in the state before entering this mode. Transitional season air cooler and chilled water air conditioning unit mixed cooling mode: When the ambient temperature T is higher than the air cooler outlet water temperature setpoint T1 and lower than the chilled water air conditioning unit return water temperature setpoint T2, the air cooler and chilled water air conditioning unit mixed cooling mode is entered during the transitional season. Summer chilled water air conditioning unit cooling mode: When the ambient temperature T is greater than or equal to the set value T2 of the chilled water air conditioning unit return water temperature, the chilled water air conditioning unit enters the summer chilled water air conditioning unit cooling mode.

2. The control method for the regulating cooling system of a chilled water air conditioning unit according to claim 1, characterized in that, It also includes an air thermometer, which is installed outdoors in the external environment, and an outlet water thermometer is installed on the outlet water pipe of the air cooler.

3. The control method for regulating the cooling system of a chilled water air conditioning unit according to claim 2, characterized in that, It includes a PLC control cabinet, an air thermometer and an outlet water thermometer electrically connected to the PLC control cabinet. The PLC control cabinet is used to control the on / off state of the isolation electric valve, the inlet electric valve, and the outlet electric valve, as well as the start and stop of the air cooler and the chilled water air conditioning unit.

4. The control method for the regulating cooling system of a chilled water air conditioning unit according to claim 1, characterized in that, The cooling fan of the air cooler is composed of a single variable frequency fan or multiple variable frequency fans connected in parallel.

5. The control method for the regulating cooling system of a chilled water air conditioning unit according to claim 1, characterized in that, When the air cooler and chilled water air conditioning unit are in mixed cooling mode during the transition season, the inlet and outlet electric valves are opened, the isolation electric valve is closed, the air cooler is put into operation, and the chilled water air conditioning unit is put into operation.

6. The control method for a regulating cooling system of a chilled water air conditioning unit according to claim 1, characterized in that, When the chilled water air conditioning unit is in cooling mode during the summer, the inlet and outlet electric valves are closed, the isolation electric valve is opened, the air cooler stops running, and the chilled water air conditioning unit is put into operation.

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