CN112377996A - Air conditioning system and control method thereof - Google Patents
Air conditioning system and control method thereof Download PDFInfo
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- CN112377996A CN112377996A CN202011290660.XA CN202011290660A CN112377996A CN 112377996 A CN112377996 A CN 112377996A CN 202011290660 A CN202011290660 A CN 202011290660A CN 112377996 A CN112377996 A CN 112377996A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
- F24F3/06—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the arrangements for the supply of heat-exchange fluid for the subsequent treatment of primary air in the room units
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
- F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
- F24F11/84—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/70—Control systems characterised by their outputs; Constructional details thereof
- F24F11/80—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
- F24F11/83—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
- F24F11/85—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using variable-flow pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F27/00—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus
- F28F27/003—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus specially adapted for cooling towers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F2140/00—Control inputs relating to system states
- F24F2140/20—Heat-exchange fluid temperature
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- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Other Air-Conditioning Systems (AREA)
- Air Conditioning Control Device (AREA)
Abstract
The present invention relates to an air conditioning system and a control method of the air conditioning system, the air conditioning system includes: the refrigerating unit comprises a water inlet for introducing cooling water and a water outlet for discharging the cooling water; the cooling towers are arranged in parallel and respectively comprise an inlet communicated with the water outlet of the refrigerating unit and an outlet communicated with the water inlet of the refrigerating unit; the water pumps are arranged in parallel and respectively comprise an outlet communicated with the water inlet of the refrigerating unit and an inlet communicated with the water outlet of the refrigerating unit so as to enable cooling water to circularly flow between the refrigerating unit and the cooling tower; the control valves are arranged in one-to-one correspondence with the cooling towers to control whether the corresponding cooling towers work or not; and a controller communicatively coupled to the plurality of control valves and configured to: and acquiring the total rated flow Q1 of the working cooling towers and the total flow Q2 of the plurality of water pumps, increasing the number of the working cooling towers when Q1 is less than Q2, and reducing the number of the working cooling towers when Q1 is more than 2 times Q2.
Description
Technical Field
The invention relates to the technical field of refrigeration, in particular to an air conditioning system and a control method of the air conditioning system.
Background
In a large central air conditioning system, a cooling tower is used as a terminal device, and heat in a refrigerator (load end) is discharged to the atmosphere through cooling water by means of a cooling water pump. For a long time, because the energy consumption ratio of the refrigerating machine to the air-conditioning box is large, the energy-saving technical research is mainly concentrated in the refrigerating machine and the air-conditioning box; and the cooling tower is used as a heat discharge end device, and the energy-saving control of the cooling tower is not taken into consideration. Generally, a refrigerator, a cooling water pump and a cooling tower are all installed on line by a plurality of devices, when the load is reduced, the number of running devices of the refrigerator, the cooling water pump and the cooling tower is reduced at the same time, for the cooling tower which is not in running, cooling water is not distributed, the cooling tower is in an idle state, and the energy efficiency of the devices is not fully exerted. In addition, in the conventional cooling water pump and cooling tower, motors of the conventional cooling water pump and cooling tower are operated at full power, the temperature of cooling water inlet and outlet water changes along with the load of the refrigerating machine and the temperature of an environmental wet bulb, and under the operation condition, the cooling tower can be in a state of large flow and low temperature difference and can also be in a state of insufficient flow and high temperature difference, so that the refrigerating machine can not be in a high-energy-efficiency operation state, the energy consumption of the cooling water pump and a fan of the cooling tower is wasted, and a large energy-saving space is provided; in the existing energy-saving control research, generally, the temperature difference between inlet water and outlet water of a fixed cooling tower is set, the frequency conversion adjustment is carried out on a fan of the cooling tower, the frequency conversion adjustment is not carried out according to the load condition of a refrigerator and the change of the temperature and the humidity of the environment, and the energy-saving space is limited.
Disclosure of Invention
The present invention aims to provide an air conditioning system and a control method of the air conditioning system that are advantageous for reducing energy consumption.
According to an aspect of an embodiment of the present invention, there is provided an air conditioning system including:
the refrigerating unit comprises a water inlet for introducing cooling water and a water outlet for discharging the cooling water;
the cooling towers are arranged in parallel and respectively comprise an inlet communicated with the water outlet of the refrigerating unit and an outlet communicated with the water inlet of the refrigerating unit;
the water pumps are arranged in parallel and respectively comprise an outlet communicated with the water inlet of the refrigerating unit and an inlet communicated with the water outlet of the refrigerating unit so as to enable cooling water to circularly flow between the refrigerating unit and the cooling tower;
the control valves are arranged in one-to-one correspondence with the cooling towers to control whether the corresponding cooling towers work or not; and
a controller communicatively coupled to the plurality of control valves and configured to: and acquiring the total rated flow Q1 of the working cooling towers and the total flow Q2 of the plurality of water pumps, increasing the number of the working cooling towers when Q1 is less than Q2, and reducing the number of the working cooling towers when Q1 is more than 2 times Q2.
In some embodiments of the present invention, the,
the cooling tower comprises a heat-radiating filler for circulating cooling water and a cooling tower fan for blowing air to the heat-radiating filler,
the air conditioning system further comprises a first temperature detecting part for measuring the outlet water temperature T1 of the cooling tower,
the controller is connected with cooling tower fan, first temperature detection part and water pump all communication to be configured into: when the water outlet temperature T1 of the cooling tower is less than or equal to the lowest target temperature Td of the water outlet of the cooling tower,
if the operation frequency ft of the fan of the cooling tower is larger than the lowest operation frequency ft0 of the fan of the cooling tower, reducing the frequency of the fan of the cooling tower;
if the operation frequency ft of the cooling tower fan is equal to the lowest operation frequency ft0 of the cooling tower fan, the cooling tower fan is closed;
if the operation frequency ft of the cooling tower fan is 0, the operation frequency of the water pump is reduced.
In some embodiments, the air conditioning system further comprises a second temperature detecting component for detecting the inlet water temperature T2 of the cooling tower and a detecting component for detecting whether the heat dissipation capacity of the cooling tower meets the requirement, and the controller is communicatively connected with both the second temperature detecting component and the detecting component and configured to: when the outlet water temperature T1 of the cooling tower is more than the lowest target temperature Td of the outlet water of the cooling tower and the heat dissipation capacity of the cooling tower meets the requirement,
if the water inlet temperature T2 of the cooling tower is not less than the highest target water inlet temperature Tg of the cooling tower, increasing the operating frequency fb of the water pump;
if the water inlet temperature T2 of the cooling tower is less than the highest target temperature Tg of the water inlet of the cooling tower, and the operating frequency ft of a fan of the cooling tower is more than the lowest operating frequency ft0 of the fan of the cooling tower, reducing the operating frequency ft of the fan of the cooling tower;
and if the inlet water temperature T2 of the cooling tower is less than the highest target inlet water temperature Tg of the cooling tower, and the operating frequency ft of the fan of the cooling tower is equal to the lowest operating frequency ft0 of the fan of the cooling tower, closing the fan of the cooling tower.
In some embodiments, the controller is configured to maintain the operating frequency fb of the water pump below a predetermined frequency.
In some embodiments, the air conditioning system further comprises a second temperature detecting component for detecting the inlet water temperature T2 of the cooling tower and a detecting component for detecting whether the heat dissipation capacity of the cooling tower meets the requirement, and the controller is communicatively connected with both the second temperature detecting component and the detecting component and configured to: when the outlet water temperature T1 of the cooling tower is more than the lowest target temperature Td of the outlet water of the cooling tower and the heat dissipation capacity of the cooling tower can not meet the requirement,
if the operating frequency ft of the fan of the cooling tower is less than the preset frequency, increasing the operating frequency ft of the fan of the cooling tower;
if the operation frequency ft of the cooling tower fan is equal to a preset frequency, increasing the operation frequency fb of the water pump;
if the operating frequency fb of the water pump is equal to the predetermined frequency, the number of cooling towers that are operated is increased.
In some embodiments, the detection component includes an air wet bulb temperature detection component that detects an air wet bulb temperature T3, and the controller is communicatively coupled to the air wet bulb temperature detection component and configured to:
and if the temperature difference delta T of the outlet water of the cooling tower is less than or equal to the temperature difference target value delta T0 of the outlet water of the cooling tower, judging that the heat dissipation capacity of the cooling tower meets the requirement, wherein the delta T is T3-T1.
In some embodiments, the air conditioning system further comprises:
the first main pipeline is provided with an inlet communicated with a water outlet of the refrigerating unit;
the branch circuits are arranged in one-to-one correspondence with the cooling towers, each branch circuit is provided with a cooling tower and a control valve, and inlets of the branch circuits are communicated with an outlet of the first main pipeline; and
and the second main pipeline is provided with an inlet communicated with the outlets of the plurality of branches and an outlet communicated with the water inlet of the refrigerating unit.
In some embodiments, the air conditioning system further comprises:
the first temperature detection component is arranged in the second main pipeline and used for detecting the outlet water temperature of the cooling tower; and/or
And the second temperature detection part is arranged on the first main pipeline and used for detecting the water inlet temperature of the cooling tower.
According to another aspect of the present invention, there is also provided a control method of an air conditioning system, the control method including:
acquiring the total rated flow Q1 of the working cooling tower and the total flow Q2 of a plurality of water pumps;
if Q1 < Q2, the number of cooling towers in operation is increased, and if Q1 > 2 × Q2, the number of cooling towers in operation is decreased.
In some embodiments, the control method further comprises: obtaining the outlet water temperature T1 of the cooling tower, when the outlet water temperature T1 of the cooling tower is less than or equal to the lowest target temperature Td of the outlet water of the cooling tower,
if the operation frequency ft of the fan of the cooling tower is larger than the lowest operation frequency ft0 of the fan of the cooling tower, reducing the frequency of the fan of the cooling tower;
if the operation frequency ft of the cooling tower fan is equal to the lowest operation frequency ft0 of the cooling tower fan, the cooling tower fan is closed;
if the operation frequency ft of the cooling tower fan is 0, the operation frequency of the water pump is reduced.
In some embodiments, the control method further comprises obtaining the inlet water temperature T2 of the cooling tower and determining whether the heat dissipation capacity of the cooling tower meets the requirement, when the outlet water temperature T1 of the cooling tower is greater than the lowest target temperature Td of the outlet water of the cooling tower and the heat dissipation capacity of the cooling tower meets the requirement,
if the water inlet temperature T2 of the cooling tower is not less than the highest target water inlet temperature Tg of the cooling tower, increasing the operating frequency fb of the water pump;
if the water inlet temperature T2 of the cooling tower is less than the highest target temperature Tg of the water inlet of the cooling tower, and the operating frequency ft of a fan of the cooling tower is more than the lowest operating frequency ft0 of the fan of the cooling tower, reducing the operating frequency ft of the fan of the cooling tower;
and if the inlet water temperature T2 of the cooling tower is less than the highest target inlet water temperature Tg of the cooling tower, and the operating frequency ft of the fan of the cooling tower is equal to the lowest operating frequency ft0 of the fan of the cooling tower, closing the fan of the cooling tower.
In some embodiments, the operating frequency fb of the water pump is maintained below a predetermined frequency.
In some embodiments, the control method further comprises obtaining the inlet water temperature T2 of the cooling tower and determining whether the heat dissipation capacity of the cooling tower meets the requirement, when the outlet water temperature T1 of the cooling tower is greater than the lowest target temperature Td of the outlet water of the cooling tower and the heat dissipation capacity of the cooling tower can not meet the requirement,
if the operating frequency ft of the fan of the cooling tower is less than the preset frequency, increasing the operating frequency ft of the fan of the cooling tower;
if the operation frequency ft of the cooling tower fan is equal to a preset frequency, increasing the operation frequency fb of the water pump;
if the operating frequency fb of the water pump is equal to the predetermined frequency, the number of cooling towers that are operated is increased.
In some embodiments, determining whether the heat rejection capacity of the cooling tower meets the requirement includes:
detecting the wet bulb temperature T3 of the air;
calculating the temperature difference delta T of the outlet water approximation degree of the cooling tower, wherein the delta T is T3-T1; and
and if the outlet water approximation degree temperature difference delta T of the cooling tower is less than or equal to the outlet water approximation temperature difference target value delta T0 of the cooling tower, judging that the heat dissipation capacity of the cooling tower meets the requirement, and if the outlet water approximation degree temperature difference delta T of the cooling tower is greater than the outlet water approximation temperature difference target value delta T0 of the cooling tower, judging that the heat dissipation capacity of the cooling tower cannot meet the requirement.
By applying the technical scheme of the invention, the number of the working cooling towers is increased when Q1 is less than Q2, and the number of the working cooling towers is reduced when Q1 is greater than 2X Q2, so that the energy consumption of the air-conditioning system is reduced.
Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the related art, the drawings needed to be used in the description of the embodiments or the related art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 shows a schematic configuration diagram of an air conditioning system of an embodiment of the present invention; and
fig. 2 is a schematic view showing an operation state of a cooling tower of an air conditioning system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 shows a schematic structural diagram of an air conditioning system according to an embodiment of the present invention, and as shown in fig. 1, the air conditioning system according to the embodiment includes a refrigeration unit 1, a plurality of cooling towers 4, a plurality of water pumps 6, a plurality of control valves 3, and a controller.
The refrigeration unit 1 comprises a water inlet for introducing cooling water and a water outlet for discharging cooling water. The refrigeration unit 1 includes a plurality of refrigeration machines, which in some embodiments are connected in parallel.
The refrigerator includes a compressor, a condenser in communication with an exhaust port of the compressor, and an evaporator in communication with an outlet of the condenser. The outlet of the evaporator is connected with the air suction port of the compressor. The cooling water introduced from the water inlet of the refrigerating unit cools the condenser.
The plurality of cooling towers 4 are arranged in parallel and respectively comprise an inlet communicated with the water outlet of the refrigerating unit 1 and an outlet communicated with the water inlet of the refrigerating unit 1. The plurality of control valves 3 are provided in one-to-one correspondence with the plurality of cooling towers 4 to control whether the respective cooling towers 4 operate.
The plurality of water pumps 6 are arranged in parallel and respectively comprise an outlet communicated with the water inlet of the refrigerating unit 1 and an inlet communicated with the water outlet of the refrigerating unit 1, so that cooling water circularly flows between the refrigerating unit 1 and the cooling tower 4.
The air conditioning system further comprises a first main line 7, a plurality of branches and a second main line 8. The first main pipeline 7 is provided with an inlet communicated with a water outlet of the refrigerating unit 1; a plurality of branches and cooling tower 4 one-to-one set up, all are provided with cooling tower 4 and control valve 3 in every branch, and the import of a plurality of branches all communicates with the export of first main line 7.
The air conditioning system further includes a first temperature detecting part 5 and a second temperature detecting part 2. The first temperature detection component 5 is arranged in the second main pipeline 8 and used for detecting the outlet water temperature of the cooling tower. The second temperature detection component 2 is arranged on the first main pipeline 7 and is used for detecting the water inlet temperature of the cooling tower 4.
The cooling tower 4 includes a heat-radiating packing for circulating cooling water and a cooling tower blower for blowing air toward the heat-radiating packing. The motor of the cooling tower fan is a variable frequency motor. The air conditioning system also includes a cooling tower fan frequency converter for controlling the rotational speed of the cooling tower fan.
The motor of the water pump 6 is also a variable frequency motor. The air conditioning system further comprises a water pump frequency converter for controlling the rotational speed of the water pump 6.
The air conditioning system further includes an air wet bulb temperature detecting part that detects the air wet bulb temperature T3. The air wet bulb temperature detection component is installed near the cooling tower.
The air conditioning system also includes a controller communicatively coupled to the air wet bulb temperature sensing component to obtain an air wet bulb temperature T3. The controller is connected with the first temperature detection part 5 in a communication mode to acquire the outlet water temperature T1 of the cooling tower. The controller is connected with the second temperature detection part 2 in a communication mode to obtain the water inlet temperature T2 of the cooling tower. The controller is in communication connection with the cooling tower fan frequency converter to control the rotating speed of the cooling tower fan. The controller is in communication connection with the water pump frequency converter to control the rotation speed of the water pump 6. The controller is connected with the control valve 3 in a communication mode so as to control whether the cooling tower 4 corresponding to the control valve 3 works or not.
The first temperature detection component 5 is a cooling tower outlet water temperature sensor. The second temperature detection component 2 is a cooling tower inlet water temperature sensor. The air wet bulb temperature detection component is an air wet bulb temperature sensor.
In some embodiments, the controller comprises a Programmable Logic Controller (PLC).
And the cooling water pump frequency converter is arranged in the cooling water pump control loop. The cooling tower fan frequency converter is arranged in a cooling tower fan control loop. The second temperature detection part 2 is installed in a water inlet pipeline of the cooling tower. The first temperature detection part 5 is arranged in the water outlet pipeline of the cooling tower. The air wet bulb temperature sensor is arranged near the cooling tower and used for measuring the air wet bulb temperature. The control valve 3 is arranged in the water inlet pipeline of each cooling tower.
The cooling tower water inlet main pipe is arranged in a cooling tower water inlet loop, is connected with a cooling water outlet pipeline of the refrigerator in parallel, and distributes water inlet pipelines to each cooling tower. The cooling water pump is arranged in the water inlet and outlet loop of the cooling tower and provides circulating cooling water for the refrigerating machine and the cooling tower; the PLC writes a logic control program, receives feedback signals of the cooling water pump frequency converter, the cooling tower fan frequency converter, the water inlet temperature sensor, the water outlet temperature sensor, the air wet bulb temperature sensor and the electric regulating valve, and sends control signals to the cooling water pump frequency converter, the cooling tower fan frequency converter and the electric regulating valve; the number of cooling towers and the number of cooling water pumps do not need to satisfy a one-to-one correspondence relationship.
The control method of the air conditioner control system comprises the following steps:
step 1: initializing operation parameters:
setting a target value delta T0 of the temperature difference of the cooling tower outlet water (the temperature difference delta T of the cooling tower outlet water is the difference between the cooling tower outlet water temperature and the environmental wet bulb temperature),
a minimum target cooling tower outlet water temperature Td is defined and set,
the highest target temperature Tg of the water inlet of the cooling tower is defined and set,
defining the outlet water temperature T1 of the cooling tower,
defining the cooling tower inlet water temperature T2,
the air wet bulb temperature T3 is defined,
defining the fan operation frequency ft of the cooling tower, setting the lowest fan operation frequency ft0 of the cooling tower,
the cooling water pump operation frequency fb is defined, the cooling water pump minimum operation frequency fb0 is set,
a frequency change step size af is defined and set,
defining a total rated circulation flow rate Q1 of cooling tower operation, defining the number n of cooling tower operation units, setting the number n of the cooling tower initial operation units as n0,
defining the total rated flow Q2 of the cooling water pump in operation;
When Q2 is more than Q1 and less than or equal to 2X Q2, n is equal to n0, namely the number of the working cooling towers 4 is unchanged;
when Q1 is greater than 2 × Q2, n is n-1, i.e., one working cooling tower 4 is decreased;
when Q1 is less than Q2, n is n +1, namely, an operating cooling tower is added;
and 4, step 4: a cooling tower water inlet temperature sensor, a cooling tower water outlet temperature sensor and an air wet bulb temperature sensor are respectively used for measuring a cooling tower water inlet temperature T2, a cooling tower water outlet temperature T1 and an air wet bulb temperature T3;
and 5: calculating the temperature difference delta T of the outlet water approximation degree of the cooling tower as T3-T1;
step 6: when T1 is less than or equal to Td:
6.1: when the cooling tower fan ft is larger than ft0, ft is ft-delta f and ft is larger than or equal to ft0, namely the rotating speed of the cooling tower fan is reduced, and the rotating speed of the cooling tower fan is kept above the lowest operating frequency ft0 of the cooling tower fan;
6.2: when the cooling tower fan ft is ft0, ft is 0, that is, the rotating speed of the cooling tower fan is reduced to 0;
6.3: when the cooling tower fan ft is equal to 0, fb is equal to fb-delta f, and fb is more than or equal to fb0, namely, the rotating speed of the water pump is reduced, and the rotating speed of the water pump 6 is kept at the lowest operating frequency fb0 of the water pump;
6.4: and after the execution is finished, continuing for a time step, and returning to the step 4.
And 7: when T1 > Td:
7.1: when Δ T ≦ Δ T0:
7.1.1: when T2 is greater than or equal to Tg: fb equals fb + Δ f and fb is less than or equal to 50, that is, the rotation speed of the water pump 6 is increased and maintained below the predetermined rotation speed;
7.1.2: when T2 is less than Tg and ft is more than ft0, ft is ft-delta f and ft is more than or equal to ft0, namely the rotating speed of the fan of the cooling tower is reduced and is kept above the lowest operating frequency ft0 of the fan of the cooling tower;
7.1.3: when T2 < Tg and ft ═ ft 0: ft is 0, namely the rotating speed of a fan of the cooling tower is reduced to 0;
7.1.4: and after the execution is finished, continuing for a time step, and returning to the step 4.
7.2: when Δ T > Δ T0:
7.2.1: when ft < 50: ft is ft + delta f and ft is less than or equal to 50, namely the rotating speed of the fan of the cooling tower is increased, and the rotating speed of the fan of the cooling tower is controlled below a preset rotating speed;
7.2.2: when ft is 50: fb equals fb + Δ f and fb is less than or equal to 50, that is, the rotation speed of the water pump 6 is increased, and the rotation speed of the water pump 6 is controlled to be lower than or equal to a predetermined rotation speed; (ii) a
7.2.3: when fb is 50 and Q1 ≦ 3 × Q2: n is n +1, namely a working cooling tower 4 is added;
7.2.4: and after the execution is finished, continuing for a time step, and returning to the step 4.
The air conditioning system of the embodiment has the following technical effects:
1. the cooling tower system is used as a subsystem of the refrigeration system, the load of the refrigeration system can be judged according to the water inlet and outlet temperature of the cooling tower, and the most appropriate cooling water flow and temperature are provided for the refrigeration system according to the environment wet bulb temperature;
2. the cooling towers are taken as a whole, the cooling towers are not in one-to-one correspondence with the cooling water pumps, when the cooling water pumps are not all put into operation, the cooling water of one cooling water pump can be distributed in two or three cooling towers, the cooling water with the same water quantity can dissipate heat in the filler with a larger area, the cooling water can be more fully dissipated, and the outlet water of the cooling towers approaches to the temperature difference to be the minimum;
3. the target value of the temperature difference of the cooling tower effluent, the minimum target temperature of the cooling tower effluent and the maximum target temperature of the cooling tower effluent are taken as control bases, and the number of the cooling tower water distribution units, the cooling water pump frequency and the cooling tower fan frequency can be adjusted by a control system along with the changes of the load of a refrigeration system and the environmental wet bulb temperature, so that the minimum energy consumption of a cooling tower subsystem is realized under the condition of meeting the requirement of the optimal cooling water required by the refrigeration system.
Specifically, 5 cooling water pumps (rated flow rate 500m3/h) and 5 cooling towers (rated cooling flow rate 600m3/h) are taken as examples to form a cooling tower energy-saving control system;
the cooling water pump frequency converter is arranged in the cooling water pump control loop;
the cooling tower fan frequency converter is arranged in a cooling tower fan control loop;
the inlet water temperature sensor is arranged in an inlet water pipeline of the cooling tower;
the water outlet temperature sensor is arranged in a water outlet pipeline of the cooling tower;
the air wet bulb temperature sensor is arranged near the cooling tower and used for measuring the air wet bulb temperature;
the electric regulating valves are arranged in the water inlet pipelines of the cooling towers;
the cooling tower water inlet main pipe is arranged in a cooling tower water inlet loop, is connected with a cooling water outlet pipeline of the refrigerator in parallel, and distributes a water inlet pipeline to each cooling tower;
the cooling water pump is arranged in a water inlet and outlet loop of the cooling tower and provides circulating cooling water for the refrigerating machine and the cooling tower;
and the PLC writes a logic control program, receives feedback signals of the cooling water pump frequency converter, the cooling tower fan frequency converter, the water inlet temperature sensor, the water outlet temperature sensor, the air wet bulb temperature sensor and the electric regulating valve, and sends control signals to the cooling water pump frequency converter, the cooling tower fan frequency converter and the electric regulating valve.
The control method can be as follows:
step 1: initializing operation parameters:
setting the temperature difference target value delta T0 of the cooling tower outlet water to be 3 ℃,
setting the lowest target temperature Td of the outlet water of the cooling tower to be 24 ℃,
setting the highest target temperature Tg of water inlet of the cooling tower to 39 ℃,
defining the fan operation frequency ft of the cooling tower, setting the lowest fan operation frequency ft0 to be 25hz,
the cooling water pump operation frequency fb is defined, the cooling water pump minimum operation frequency fb0 is set to 30hz,
setting a frequency change step length delta f as 5 hz;
defining a total rated circulation flow rate Q1 of cooling tower operation, defining the number n of cooling tower operation units, setting the number n of cooling tower initial operation units to be n0 to be 2,
defining the total rated flow Q2 of the cooling water pump in operation;
when Q2 < Q1 ≦ 2 × Q2: n-n 0;
when the total rated circulation flow Q1 of the cooling tower in operation is more than 2 and the total rated flow Q2 of the cooling water pump in operation: the cooling tower exits from 1 operation;
when the total rated circulation flow Q1 of the cooling tower in operation is less than the total rated flow Q2 of the cooling water pump in operation: 1 cooling tower is added for operation;
otherwise, the number of the cooling towers is unchanged;
and 4, step 4: a cooling tower water inlet temperature sensor, a cooling tower water outlet temperature sensor and an air wet bulb temperature sensor are respectively used for measuring a cooling tower water inlet temperature T2, a cooling tower water outlet temperature T1 and an air wet bulb temperature T3;
and 5: calculating the temperature difference delta T of the outlet water approximation degree of the cooling tower as T3-T1;
step 6: when T1 is less than or equal to 24: the cooling tower runs in the first zone of fig. 2, the temperature of the cooling water is low,
6.1: if the cooling tower fan is in an operating state, reducing the operating frequency of the fan by one step length, wherein the frequency is more than or equal to 25 hz;
6.2: if the frequency of the cooling tower fan is reduced to 25hz, stopping the cooling tower fan;
6.3: if the fan of the cooling tower is stopped, reducing the frequency of the cooling water pump by one step length, wherein the frequency is required to be more than or equal to 30 hz;
6.4: and after the execution is finished, continuing for a time step, and returning to the step 4.
And 7: when T1 > 24: the cooling water temperature does not fall to the minimum target temperature,
7.1: when the delta T is less than or equal to 3, namely the temperature difference of the outlet water of the cooling tower is small, the cooling water is fully radiated by the cooling tower, and the temperature of the outlet water of the cooling tower can not be further reduced:
7.1.1: if T2 is more than or equal to 39 ℃: the cooling tower operates in the second area of fig. 2, when the inlet water temperature of the cooling tower is higher, the frequency of the cooling water pump is increased by one step, but the frequency is not more than 50 hz;
7.1.2: if T2 < 39 ℃: the cooling tower operates in the third area of fig. 2, when the fan frequency is greater than 25hz, the fan operating frequency is reduced by one step length, but the frequency is not less than 25 hz; if T2 < 39 ℃: when the frequency of the fan is equal to 25hz, stopping the fan from running;
7.1.3: and after the execution is finished, continuing for a time step, and returning to the step 4.
7.2: when Δ T > 3: the cooling tower operates in the fourth area of fig. 2, the cooling water is insufficiently radiated by the cooling tower:
7.2.1: if ft < 50: increasing the fan frequency of the cooling tower by one step, wherein the frequency is not more than 50 hz;
7.2.2: if ft is 50: the cooling water pump frequency is increased by one step but not more than 50 hz.
7.2.3: if fb is 50 and Q1 is less than or equal to 3Q 2: one cooling tower is additionally provided for operation;
7.2.4: and after the execution is finished, continuing for a time step, and returning to the step 4.
Through the control and regulation, the energy-saving control system for the cooling tower can fully exert the heat dissipation capacity of the heat dissipation filler of the existing cooling tower, takes the load of a refrigeration system as the control requirement, and timely and effectively regulates the number of water distribution units, the frequency of a cooling water pump and the frequency of a fan of the cooling tower according to the temperature change of an environmental wet bulb, thereby effectively saving energy consumption.
The present invention is not limited to the above exemplary embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (14)
1. An air conditioning system, comprising:
a refrigerating unit (1) comprising a water inlet for introducing cooling water and a water outlet for discharging cooling water;
the cooling towers (4) are arranged in parallel and respectively comprise an inlet communicated with the water outlet of the refrigerating unit (1) and an outlet communicated with the water inlet of the refrigerating unit (1);
the water pumps (6) are arranged in parallel and respectively comprise an outlet communicated with a water inlet of the refrigerating unit (1) and an inlet communicated with a water outlet of the refrigerating unit (1) so as to enable cooling water to circularly flow between the refrigerating unit (1) and the cooling tower (4);
the control valves (3) are arranged in one-to-one correspondence with the cooling towers (4) to control whether the corresponding cooling towers (4) work or not; and
a controller communicatively connected to a plurality of the control valves (3) and configured to: and acquiring the total rated flow Q1 of the working cooling tower (4) and the total flow Q2 of the plurality of water pumps (6), increasing the number of the working cooling towers (4) when Q1 is less than Q2, and reducing the number of the working cooling towers (4) when Q1 is more than 2X Q2.
2. The air conditioning system of claim 1,
the cooling tower (4) comprises a heat-radiating filler for circulating cooling water and a cooling tower fan for blowing air to the heat-radiating filler,
the air conditioning system also comprises a first temperature detection component (5) for measuring the outlet water temperature T1 of the cooling tower (4),
the controller is in communication connection with the cooling tower fan, the first temperature detection component (5) and the water pump (6) to be configured to: when the water outlet temperature T1 of the cooling tower (4) is not more than the lowest target temperature Td of the water outlet of the cooling tower,
if the operation frequency ft of the fan of the cooling tower is larger than the lowest operation frequency ft0 of the fan of the cooling tower, reducing the frequency of the fan of the cooling tower;
if the operation frequency ft of the cooling tower fan is equal to the lowest operation frequency ft0 of the cooling tower fan, closing the cooling tower fan;
and if the operation frequency ft of the cooling tower fan is equal to 0, the operation frequency of the water pump (6) is reduced.
3. Air conditioning system according to claim 2, further comprising second temperature detection means (2) for detecting the incoming water temperature T2 of the cooling tower (4) and detection means for detecting whether the heat dissipation capacity of the cooling tower (4) meets the requirement, the controller being communicatively connected to both the second temperature detection means (2) and the detection means and being configured to: when the outlet water temperature T1 of the cooling tower (4) is more than the lowest target outlet water temperature Td of the cooling tower and the heat dissipation capacity of the cooling tower (4) meets the requirement,
if the water inlet temperature T2 of the cooling tower (4) is not less than the highest target water inlet temperature Tg of the cooling tower, increasing the operating frequency fb of the water pump;
if the water inlet temperature T2 of the cooling tower (4) is less than the highest target temperature Tg of the water inlet of the cooling tower, and the operating frequency ft of the fan of the cooling tower is more than the lowest operating frequency ft0 of the fan of the cooling tower, reducing the operating frequency ft of the fan of the cooling tower;
and if the water inlet temperature T2 of the cooling tower (4) is less than the highest target temperature Tg of the water inlet of the cooling tower, and the operating frequency ft of the fan of the cooling tower is equal to the lowest operating frequency ft0 of the fan of the cooling tower, closing the fan of the cooling tower.
4. The air conditioning system of claim 3, wherein the controller is configured to maintain the operating frequency fb of the water pump below a predetermined frequency.
5. Air conditioning system according to claim 2, further comprising second temperature detection means (2) for detecting the incoming water temperature T2 of the cooling tower (4) and detection means for detecting whether the heat dissipation capacity of the cooling tower (4) meets the requirement, the controller being communicatively connected to both the second temperature detection means (2) and the detection means and being configured to: when the outlet water temperature T1 of the cooling tower (4) is more than the lowest target outlet water temperature Td of the cooling tower and the heat dissipation capacity of the cooling tower (4) can not meet the requirement,
if the operating frequency ft of the fan of the cooling tower is less than the preset frequency, increasing the operating frequency ft of the fan of the cooling tower;
if the operation frequency ft of the cooling tower fan is equal to a preset frequency, increasing the operation frequency fb of the water pump;
and if the operating frequency fb of the water pump (6) is equal to a predetermined frequency, increasing the number of the operating cooling towers (4).
6. The air conditioning system of any of claims 3-5, wherein the detection component comprises an air wet bulb temperature detection component that detects an air wet bulb temperature T3, the controller communicatively coupled to the air wet bulb temperature detection component and configured to:
and if the temperature difference delta T of the outlet water of the cooling tower is less than or equal to the temperature difference target value delta T0 of the outlet water of the cooling tower, judging that the heat dissipation capacity of the cooling tower (4) meets the requirement, wherein the delta T is T3-T1.
7. The air conditioning system of claim 1, further comprising:
a first main line (7) having an inlet communicating with a water outlet of the refrigeration unit (1);
the branches are arranged in one-to-one correspondence with the cooling tower (4), each branch is provided with the cooling tower (4) and the control valve (3), and inlets of the branches are communicated with an outlet of the first main pipeline (7); and
a second main line (8) having an inlet communicating with the outlets of the plurality of branches and an outlet communicating with the water inlet of the refrigeration unit (1).
8. The air conditioning system of claim 7, further comprising:
the first temperature detection component (5) is arranged in the second main pipeline (8) and is used for detecting the outlet water temperature of the cooling tower; and/or
And the second temperature detection part (2) is arranged on the first main pipeline (7) and is used for detecting the water inlet temperature of the cooling tower (4).
9. A control method of an air conditioning system according to any one of claims 1 to 8, characterized by comprising:
obtaining the total rated flow Q1 of the working cooling tower (4) and the total flow Q2 of a plurality of water pumps (6);
if Q1 < Q2, the number of active cooling towers (4) is increased, and if Q1 > 2 × Q2, the number of active cooling towers (4) is decreased.
10. The control method according to claim 9, characterized by further comprising: obtaining the outlet water temperature T1 of the cooling tower (4), when the outlet water temperature T1 of the cooling tower (4) is not more than the lowest target temperature Td of the outlet water of the cooling tower,
if the operation frequency ft of the fan of the cooling tower is larger than the lowest operation frequency ft0 of the fan of the cooling tower, reducing the frequency of the fan of the cooling tower;
if the operation frequency ft of the cooling tower fan is equal to the lowest operation frequency ft0 of the cooling tower fan, closing the cooling tower fan;
and if the operation frequency ft of the cooling tower fan is equal to 0, the operation frequency of the water pump (6) is reduced.
11. The control method according to claim 9, further comprising obtaining the inlet water temperature T2 of the cooling tower (4) and determining whether the heat dissipation capacity of the cooling tower (4) meets the requirement, when the outlet water temperature T1 of the cooling tower (4) is greater than the lowest target cooling tower outlet water temperature Td and the heat dissipation capacity of the cooling tower (4) meets the requirement,
if the water inlet temperature T2 of the cooling tower (4) is not less than the highest target water inlet temperature Tg of the cooling tower, increasing the operating frequency fb of the water pump;
if the water inlet temperature T2 of the cooling tower (4) is less than the highest target temperature Tg of the water inlet of the cooling tower, and the operating frequency ft of the fan of the cooling tower is more than the lowest operating frequency ft0 of the fan of the cooling tower, reducing the operating frequency ft of the fan of the cooling tower;
and if the water inlet temperature T2 of the cooling tower (4) is less than the highest target temperature Tg of the water inlet of the cooling tower, and the operating frequency ft of the fan of the cooling tower is equal to the lowest operating frequency ft0 of the fan of the cooling tower, closing the fan of the cooling tower.
12. The control method according to claim 11, characterized in that the operating frequency fb of the water pump is maintained below a predetermined frequency.
13. The control method according to claim 9, further comprising obtaining the inlet water temperature T2 of the cooling tower (4) and determining whether the heat dissipation capacity of the cooling tower (4) meets the requirement, when the outlet water temperature T1 of the cooling tower (4) is greater than the lowest target cooling tower outlet water temperature Td and the heat dissipation capacity of the cooling tower (4) cannot meet the requirement,
if the operating frequency ft of the fan of the cooling tower is less than the preset frequency, increasing the operating frequency ft of the fan of the cooling tower;
if the operation frequency ft of the cooling tower fan is equal to a preset frequency, increasing the operation frequency fb of the water pump;
and if the operating frequency fb of the water pump (6) is equal to a predetermined frequency, increasing the number of the operating cooling towers (4).
14. The control method according to claim 9, wherein the interrupting of the heat dissipation capacity of the cooling tower (4) to meet the requirement comprises:
detecting the wet bulb temperature T3 of the air;
calculating the temperature difference delta T of the outlet water approximation degree of the cooling tower, wherein the delta T is T3-T1; and
and if the cooling tower outlet water approach temperature difference delta T is less than or equal to the cooling tower outlet water approach temperature difference target value delta T0 delta T0, judging that the heat dissipation capacity of the cooling tower (4) meets the requirement, and if the cooling tower outlet water approach temperature difference delta T is greater than the cooling tower outlet water approach temperature difference target value delta T0, judging that the heat dissipation capacity of the cooling tower (4) cannot meet the requirement.
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| CN115235286A (en) * | 2022-07-25 | 2022-10-25 | 贵州汇通华城股份有限公司 | Heat exchange frequency adjusting method and system |
| CN116412605A (en) * | 2023-03-17 | 2023-07-11 | 通威微电子有限公司 | Cooling system and cooling method |
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| CN115235286B (en) * | 2022-07-25 | 2023-04-04 | 贵州汇通华城股份有限公司 | Heat exchange frequency adjusting method and system |
| CN116412605A (en) * | 2023-03-17 | 2023-07-11 | 通威微电子有限公司 | Cooling system and cooling method |
| CN116412605B (en) * | 2023-03-17 | 2024-01-05 | 通威微电子有限公司 | Cooling system and cooling method |
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