CN112178873A - Adjusting and controlling method of water chilling unit and water chilling unit - Google Patents
Adjusting and controlling method of water chilling unit and water chilling unit Download PDFInfo
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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
- F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
- F24F11/46—Improving electric energy efficiency or saving
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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
- F24F11/50—Control or safety arrangements characterised by user interfaces or communication
- F24F11/61—Control or safety arrangements characterised by user interfaces or communication using timers
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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
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/64—Electronic processing using pre-stored data
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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
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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
- 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
- F24F11/87—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling absorption or discharge of heat in outdoor 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
- F24F11/87—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling absorption or discharge of heat in outdoor units
- F24F11/871—Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling absorption or discharge of heat in outdoor units by controlling outdoor fans
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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
Abstract
The invention discloses a regulation control method of a water chilling unit and the water chilling unit. The regulation control method comprises the following steps: judging whether the water chilling unit meets set natural cooling conditions or not; if so, closing the compressor, starting the liquid pump, and exchanging heat between the refrigerating solution cooled by the outdoor heat exchanger group and the chilled water at the user side; detecting the operation parameters of the water chilling unit; and judging the load change of the water chilling unit according to the operation parameters and adjusting the heat exchange amount of the outdoor heat exchanger group. The invention achieves the effects of quick response, reliability and energy saving according to the load change during natural cooling and refrigeration by adjusting the heat exchange amount of the outdoor heat exchanger group.
Description
Technical Field
The invention relates to the technical field of water chilling units, in particular to a regulation and control method of a water chilling unit and the water chilling unit.
Background
The data center generally needs year-round refrigeration, the refrigeration equipment used in the data center generally adopts a water chilling unit with a natural cooling function at present, and the natural cooling refrigeration is completely adopted when the temperature is lower than 0 ℃ in winter, wherein the natural cooling mode of the water chilling unit is a refrigeration mode that an ethylene glycol water pump is utilized, ethylene glycol water solution is used as a cooling medium to circulate outdoor cold energy into a heat exchanger, and the chilled water on the other side of the heat exchanger takes away the cold energy.
The water chilling unit with the natural cooling function has appeared in the prior art, and it can change the running mode of water chilling unit after ambient temperature reaches the natural cooling condition, switches to the natural cooling refrigeration from conventional compressor refrigeration, and the natural cooling refrigeration scheme is when the load changes, how the water chilling unit is quick accurate response load change to reach energy-conserving effect under safe and reliable's prerequisite and be the technological problem that the industry is urgent to wait to solve.
Disclosure of Invention
In order to overcome the defect that the existing natural cooling refrigeration scheme cannot quickly respond to load change, the invention provides the adjusting control method of the water chilling unit and the water chilling unit.
The invention adopts the technical scheme that a regulation control method of a water chilling unit is designed, and the water chilling unit comprises a compressor refrigeration loop and a natural cooling loop, wherein the compressor refrigeration loop is driven by a compressor to circulate refrigerant, and the natural cooling loop is driven by a liquid pump to circulate solution. The regulation control method comprises the following steps: judging whether the water chilling unit meets set natural cooling conditions or not; if so, closing the compressor, starting the liquid pump, and exchanging heat between the refrigerating solution cooled by the outdoor heat exchanger group and the chilled water at the user side; detecting the operation parameters of the water chilling unit; and judging the load change of the water chilling unit according to the operation parameters and adjusting the heat exchange amount of the outdoor heat exchanger group.
In one embodiment, the operating parameter is the actual leaving water temperature after chilled water heat exchange.
Preferably, the judging the load change of the water chilling unit and adjusting the heat exchange amount of the outdoor heat exchanger group according to the operation parameters comprises:
judging the section of the actual outlet water temperature and executing a corresponding control strategy;
if the actual outlet water temperature T3-target outlet water temperature is larger than a first set value Ta continuously detected for T1 seconds, executing a load-increasing control strategy, and increasing the heat exchange quantity of the outdoor heat exchanger group;
and/or if the actual outlet water temperature T3-the target outlet water temperature is less than or equal to a second set value Tb is detected for T1 seconds continuously, executing a load reduction control strategy, and reducing the heat exchange amount of the outdoor heat exchanger group;
and/or if the second set value Tb is less than the actual outlet water temperature T3 and the target outlet water temperature is less than or equal to the first set value Ta, executing a maintenance control strategy and keeping the current running state of the water chilling unit unchanged.
And after the control strategy is executed each time, the set time is operated, the interval of the outlet water temperature is continuously judged, and the corresponding control strategy is executed until the heat exchange quantity of the outdoor heat exchanger group reaches a set upper limit value or a set lower limit value.
Preferably, the outdoor heat exchanger group comprises at least two outdoor heat exchangers arranged in parallel. Adjusting the amount of heat exchanged by the outdoor heat exchanger group includes adjusting the number of outdoor heat exchangers participating in the operation in the outdoor heat exchanger group.
Preferably, the outdoor heat exchangers in the outdoor heat exchanger group are provided with corresponding serial numbers according to the priority of opening, the opening sequence is from the outdoor heat exchanger with the smallest serial number to the outdoor heat exchanger with the largest serial number, and the closing sequence is from the outdoor heat exchanger with the largest serial number to the outdoor heat exchanger with the smallest serial number.
Preferably, the number of the outdoor heat exchangers participating in the work in each regulation of the outdoor heat exchanger group is increased by 1 or decreased by 1.
Preferably, the outdoor heat exchanger which is firstly started in the outdoor heat exchanger group is an adjusting heat exchanger, and the adjusting heat exchanger adopts a variable frequency fan. And adjusting the heat exchange quantity of the outdoor heat exchanger group further comprises adjusting the operating frequency of the variable frequency fan.
Preferably, the operation frequency of the variable frequency fan is adjusted each time, the set amplitude is only increased or reduced.
Preferably, when only the adjusting heat exchanger in the outdoor heat exchanger group participates in the work, the number of the outdoor heat exchangers participating in the work in the outdoor heat exchanger group is increased after the operating frequency of the variable frequency fan is increased to the set highest frequency.
Preferably, when only the adjusting heat exchanger in the outdoor heat exchanger group participates in the work, the liquid pump stops working after the operating frequency of the variable frequency fan is reduced to be closed, and the water chilling unit enters a standby state.
Preferably, the adjusting of the heat exchange amount of the outdoor heat exchanger group further comprises adjusting the flow rate of the refrigerant solution in the natural cooling loop.
In one embodiment, the liquid pump is a variable frequency liquid pump, and adjusting the flow rate of the refrigerant solution in the natural cooling loop includes adjusting the operating frequency of the variable frequency liquid pump.
The operation frequency of the variable frequency liquid pump is adjusted to (rated frequency divided by n) multiplied by n1, n is the total number of the outdoor heat exchangers in the outdoor heat exchanger group, and n1 is the number of the outdoor heat exchangers participating in the work in the outdoor heat exchanger group.
In another embodiment, the liquid pump is a fixed-frequency liquid pump, the liquid pump is connected with a bypass circuit, the bypass circuit and the natural cooling circuit are connected to the liquid pump in parallel, and a control valve with adjustable opening degree is arranged in the bypass circuit.
The invention also provides a water chilling unit which comprises a controller, wherein the controller adopts the adjusting control method to control the running state of the water chilling unit.
Compared with the prior art, the invention judges the load change of the water chilling unit by detecting the operation parameters of the water chilling unit, adjusts the heat exchange amount of the outdoor heat exchanger group according to the load change, quickly and accurately responds the load change requirement of a user side by adjusting the number of the outdoor heat exchangers participating in the work, the rotating speed of the liquid pump and the rotating speed of the variable frequency fan, has high adjustment precision, can adapt to the load change requirement in a wider range, and can operate the water chilling unit more energy-saving and more reliable.
Drawings
The invention is described in detail below with reference to examples and figures, in which:
FIG. 1 is a schematic diagram of the heat exchange flow direction of the water chilling unit of the present invention;
FIG. 2 is a schematic flow chart of an embodiment of the present invention.
Detailed Description
As shown in fig. 1, the regulation and control method provided by the present invention is suitable for a chiller with a natural cooling function, and the chiller has a specific structure as follows, and includes a controller 5, a compressor refrigeration loop, a natural cooling loop and a chilled water circulation loop, wherein the compressor refrigeration loop and the natural cooling loop are two mutually independent liquid circulation loops, and can respectively and independently provide cold energy for the chilled water circulation loop, and also can jointly provide cold energy for the chilled water circulation loop.
The controller 5 regulates and controls the operation states of the respective components in the compressor refrigeration circuit, the natural cooling circuit, and the chilled water circulation circuit. The compressor refrigeration circuit is provided with a condenser 6, an evaporator 7 and a compressor 8, and a refrigerant is driven to circulate by the compressor 8 in the compressor refrigeration circuit. The natural cooling loop is provided with an outdoor heat exchanger group 3, an intermediate heat exchanger 1 and a liquid pump 2, the liquid pump 2 is connected between the outdoor heat exchanger group 3 and the intermediate heat exchanger 1, a refrigerating solution is driven to circulate by the liquid pump 2 in the natural cooling loop, and the refrigerating solution can be a conventional refrigerant or an aqueous solution added with an antifreezing solution. The chilled water circulation loop is provided with a chilled water pump, and chilled water on the user side is driven to circulate in the chilled water circulation loop through the chilled water pump.
The intermediate heat exchanger 1 and the evaporator 7 are both provided with two sets of heat exchange tubes, one set of heat exchange tubes of the intermediate heat exchanger 1 is connected in the natural cooling loop and used for circulating refrigerants, and the other set of heat exchange tubes is connected in the chilled water circulation loop and used for circulating chilled water. One set of heat exchange tubes of the evaporator 7 is connected in the compressor refrigeration loop for circulating the refrigeration solution, and the other set of heat exchange tubes is connected in the chilled water circulation loop for circulating the chilled water.
The unit connection diagram of the preferred embodiment is shown in fig. 1, pipe sections exchanging heat with the intermediate heat exchanger 1 and the evaporator 7 in the chilled water circulation loop are called as working sections, the intermediate heat exchanger 1 and the evaporator 7 are connected in series on the working sections, one end of each working section is a chilled water inlet, the other end of each working section is a chilled water outlet, the position of the intermediate heat exchanger 1 is close to the chilled water inlet, the position of the evaporator 7 is close to the chilled water outlet, and chilled water firstly passes through the intermediate heat exchanger 1 and then passes through the evaporator 7 in the flowing process.
When the compressor 8 is closed and the liquid pump 2 is opened, the refrigeration loop of the compressor 8 stops working, the refrigeration solution in the natural cooling loop enters the intermediate heat exchanger 1 to exchange heat with chilled water after being cooled and cooled by the cold energy of the environment absorbed by the outdoor heat exchanger group 3, the temperature of the refrigeration solution is reduced after the heat exchange of the chilled water and is supplied to a user side for use, the chilled water outlet of the chilled water circulation loop is provided with the temperature sensor 4 for detecting the actual outlet water temperature after the heat exchange of the chilled water, and the actual outlet water temperature T3 recorded in the following text refers to the actual outlet water temperature after the heat exchange of the chilled water. Of course, the temperature sensor 4 may be installed at a position between the evaporator 7 and the intermediate heat exchanger 1 in order to more accurately reflect the condition of the chilled water after heat exchange with the natural cooling circuit.
In a preferred embodiment, the outdoor heat exchanger group 3 is composed of at least two outdoor heat exchangers arranged in parallel, and each outdoor heat exchanger comprises a dry cooler and a fan group which is matched with the dry cooler for assembly. The outdoor heat exchangers in the outdoor heat exchanger group 3 are provided with corresponding serial numbers according to the priority of opening, the opening sequence is from the outdoor heat exchanger with the smallest serial number to the outdoor heat exchanger with the largest serial number, namely from the outdoor heat exchanger with the serial number of 1#, to the outdoor heat exchanger with the serial number of n #, and the closing sequence is from the outdoor heat exchanger with the largest serial number to the outdoor heat exchanger with the smallest serial number, namely from the outdoor heat exchanger with the serial number of n # to the outdoor heat exchanger with the serial number of 1 #. Except the outdoor heat exchanger with the serial number of 1#, other outdoor heat exchangers in the outdoor heat exchanger group 3 are all provided with corresponding electromagnetic valves and one-way valves, and the one-way valves are arranged at the liquid outlets of the outdoor heat exchangers to prevent refrigerating solution from reversely flowing back to the liquid outlets of the outdoor heat exchangers. The electromagnetic valve is arranged at the liquid inlet of the outdoor heat exchanger, the on-off state of the corresponding outdoor heat exchanger is independently controlled through the electromagnetic valve, the corresponding outdoor heat exchanger participates in work when the electromagnetic valve is opened, the corresponding outdoor heat exchanger stops working when the electromagnetic valve is closed, and the number of the outdoor heat exchangers participating in work in the outdoor heat exchanger group 3 can be flexibly adjusted through controlling the electromagnetic valve.
The regulation control method of the invention combines the hardware structure of the water chilling unit to carry out control regulation, and specifically comprises the following steps:
judging whether the water chilling unit meets set natural cooling conditions or not;
if so, the compressor is closed, the liquid pump 2 is started, and the refrigerating solution cooled by the outdoor heat exchanger group 3 exchanges heat with the chilled water;
detecting the operation parameters of the water chilling unit;
and judging the load change of the water chilling unit according to the operation parameters and adjusting the heat exchange amount of the outdoor heat exchanger group 3.
It should be noted that the natural cooling condition is set such that the difference between the actual ambient temperature and the target outlet water temperature of the chilled water detected continuously for a certain period of time is greater than or equal to a set difference, the value of the certain period of time may be 2 minutes or 3 minutes, and the range of the set difference may be 8 to 10 degrees. The natural cooling condition may be set by only detecting the external ambient temperature, or may be set as another condition according to the actual situation, which is not limited by the present invention.
Further, it should be understood that after the water chiller is determined to satisfy the set natural cooling condition, if the water chiller is in the standby state, the outdoor heat exchanger group 3 is turned on, and the liquid pump 2 is turned on. After the water chilling unit is judged to meet the set natural cooling condition, if the water chilling unit is in the compressor refrigeration state, the compressor 8 is closed, the water chilling unit enters the standby state, the outdoor heat exchanger group 3 is started, the liquid pump 2 is started, and the refrigeration mode is switched stably to protect the stable operation of the water chilling unit.
In a preferred embodiment, the operation parameter is an actual outlet water temperature after heat exchange of chilled water, the actual outlet water temperature can be compared with a target outlet water temperature, the target outlet water temperature is a set outlet water temperature input by a user on a display, if the actual outlet water temperature is much higher than the target outlet water temperature, the refrigerating capacity of the unit is insufficient, and the outlet water temperature can be reduced to the target outlet water temperature set by the user by increasing the refrigerating capacity after load is increased. In a common state, the regulation and control of the water chilling unit takes the fact that the actual outlet water temperature of chilled water reaches the target outlet water temperature as a unique index, the target outlet water temperature is unchanged no matter how the unit lifts or lowers the load, only when the load changes, the inlet water temperature fluctuates, the outlet water temperature is further influenced, and then the unit carries out lifting load regulation on the actual outlet water temperature after fluctuation, so that the actual outlet water temperature is kept stable. The load here refers to a cooling load.
Specifically, the step of judging the load change of the water chilling unit according to the actual outlet water temperature T3 and adjusting the heat exchange amount of the outdoor heat exchanger group includes:
judging the section of the actual outlet water temperature and executing a corresponding control strategy;
there are three control strategies, which are: when the actual outlet water temperature T3-the target outlet water temperature is larger than the first set value Ta is detected for T1 seconds continuously, a load-increasing control strategy is executed, and the heat exchange amount of the outdoor heat exchanger group 3 is increased; if the actual outlet water temperature T3-the target outlet water temperature is less than or equal to a second set value Tb is detected for T1 seconds continuously, a load reduction control strategy is executed, and the heat exchange amount of the outdoor heat exchanger group 3 is reduced; and if the second set value Tb is less than the actual water outlet temperature T3 and the target water outlet temperature is less than or equal to the first set value Ta, executing a maintenance control strategy and keeping the current running state of the water chilling unit unchanged.
And after the control strategy is executed each time, the set time is operated, the section where the actual outlet water temperature T3 is located is continuously judged, and the corresponding control strategy is executed until the heat exchange quantity of the outdoor heat exchanger group 3 reaches the set upper limit value or the set lower limit value.
It should be noted that the first set value Ta is higher than the second set value Tb, and in a preferred embodiment, Ta >0 and Tb = -Ta, and one or more of the above three control strategies may be arbitrarily selected and combined.
As shown in fig. 2, taking only the load-increasing control strategy in the adjustment control method as an example, the determining the load change of the water chilling unit according to the outlet water temperature and adjusting the heat exchange amount of the outdoor heat exchanger group 3 includes:
judging whether the actual water outlet temperature T3-target water outlet temperature is larger than a first set value Ta is detected for continuous T1 seconds;
if so, judging that the load of the water chilling unit rises, executing a load-rising control strategy, and increasing the heat exchange quantity of the outdoor heat exchanger group 3;
if not, keeping the current running state of the water chilling unit unchanged;
after the operation for a set time;
and repeating the step of judging whether the actual outlet water temperature T3-the target outlet water temperature is larger than the first set value Ta is detected for continuous T1 seconds or not until the heat exchange amount of the outdoor heat exchanger group 3 reaches the set upper limit value.
The regulation control method is mainly used for meeting the load, preventing the indoor temperature from rising and ensuring that the refrigerating capacity of the water chilling unit fully meets the load requirement.
Taking only the load reduction control strategy in the regulation control method as an example, judging the load change of the water chilling unit according to the outlet water temperature and regulating the heat exchange amount of the outdoor heat exchanger group 3 comprises the following steps:
judging whether the actual water outlet temperature T3-the target water outlet temperature is less than or equal to a second set value Tb is detected continuously for T1 seconds;
if so, judging that the load of the water chilling unit is reduced, executing a load reduction control strategy, and reducing the heat exchange quantity of the outdoor heat exchanger group 3;
if not, keeping the current running state of the water chilling unit unchanged;
after the operation for a set time;
and repeating the step of judging whether the actual outlet water temperature T3-the target outlet water temperature is less than or equal to a second set value Tb continuously for T1 seconds until the heat exchange amount of the outdoor heat exchanger group 3 reaches a set lower limit value.
The regulation control method mainly saves energy of the water chilling unit, and properly reduces the heat exchange quantity of the outdoor heat exchanger group 3 on the basis of meeting the load change, so that the water chilling unit can operate in an energy-saving mode.
Further, adjusting the heat exchange amount of the outdoor heat exchanger group 3 includes adjusting the number of outdoor heat exchangers participating in the work in the outdoor heat exchanger group 3, and the larger the number of outdoor heat exchangers participating in the work is, the larger the heat exchange amount is. When the liquid pump 2 is started initially, only the outdoor heat exchanger 1# with the minimum number in order in the outdoor heat exchanger group 3 participates in work, and in the subsequent judgment control process, the number of the outdoor heat exchangers participating in the work in the outdoor heat exchanger group 3 is adjusted by only increasing 1 or reducing 1, so that the heat exchange quantity adjusting precision of the outdoor heat exchanger group 3 is higher, and the heat exchange quantity is adjusted more accurately.
Furthermore, the outdoor heat exchanger which is firstly started in the outdoor heat exchanger group 3 is an adjusting heat exchanger, namely the outdoor heat exchanger 1# with the smallest sequence number is the adjusting heat exchanger, the adjusting heat exchanger adopts a variable frequency fan, and when the liquid pump 2 is initially started, the operating frequency of the variable frequency fan is the set highest frequency. Adjusting the heat exchange amount of the outdoor heat exchanger group 3 further comprises adjusting the operating frequency of the variable frequency fan, wherein the higher the operating frequency of the variable frequency fan is, the higher the heat exchange amount of the outdoor heat exchanger group 3 is.
All outdoor heat exchangers can adopt variable frequency fans, the control precision of the outlet water temperature is higher, but the difficulty of control logic is increased, and the reliability of a control method is reduced. In order to simplify the control logic, only the adjusting heat exchangers in the outdoor heat exchanger group 3 adopt variable frequency fans, the other outdoor heat exchangers all adopt fixed frequency fans, and the operating frequency of the variable frequency fans is only executed when only the adjusting heat exchangers in the outdoor heat exchanger group 3 participate in the work, namely when two or more outdoor heat exchangers participate in the work, only the number of the outdoor heat exchangers participating in the work in the outdoor heat exchanger group 3 is adjusted.
When only the adjusting heat exchanger in the outdoor heat exchanger group 3 participates in the work, if the actual outlet water temperature T3 is lower than the second set value Tb, the operating frequency of the variable frequency fan is reduced, after the set time of the operation, the section where the outlet water temperature is located is continuously judged and the corresponding control strategy is executed until the operating frequency of the variable frequency fan is reduced to be closed, the liquid pump 2 stops working, and the water chilling unit enters a standby state. And if the actual outlet water temperature T3 is higher than the first set value Ta, increasing the operating frequency of the variable frequency fan, operating for a set time, continuously judging the interval where the actual outlet water temperature T3 is located, executing a corresponding control strategy, and increasing the number of outdoor heat exchangers participating in work in the outdoor heat exchanger group 3 after the operating frequency of the variable frequency fan is increased to a set maximum frequency.
It should be noted that the operating frequency of the variable frequency fan is adjusted each time, the set amplitude is only increased or decreased, the set amplitude may be 5%, the specific value may be designed according to the actual situation, and the smaller the set amplitude is, the higher the adjustment accuracy of the outlet water temperature is.
Still further, adjusting the heat exchange amount of the outdoor heat exchanger group 3 further includes adjusting the refrigerant solution flow rate in the natural cooling loop, mainly to ensure that the branch flow rate flowing through each outdoor heat exchanger is kept unchanged basically when the number of the outdoor heat exchangers participating in the operation is changed, but the flow rate is certainly slightly fluctuated.
In a preferred embodiment, the liquid pump 2 is a variable frequency liquid pump, and adjusting the heat exchange amount of the outdoor heat exchanger group 3 further includes adjusting the operating frequency of the variable frequency liquid pump. The operation frequency of the variable frequency liquid pump is adjusted to (rated frequency divided by n) xn 1, n is the total number of outdoor heat exchangers in the outdoor heat exchanger group 3, n1 is the number of outdoor heat exchangers participating in work in the outdoor heat exchanger group 3, and the operation frequency of the liquid pump 2 and the number of outdoor heat exchangers participating in work in the outdoor heat exchanger group 3 are synchronously adjusted.
In an alternative embodiment, the liquid pump 2 is a constant-frequency liquid pump, the constant-frequency liquid pump is connected with a bypass circuit, the bypass circuit and the natural cooling circuit are connected to the constant-frequency liquid pump in parallel, a control valve with adjustable opening degree is arranged in the bypass circuit, the larger the opening degree of the control valve is, the smaller the flow rate of the refrigerant solution in the refrigeration circuit of the compressor is, and conversely, the smaller the opening degree of the control valve is, the larger the flow rate of the refrigerant solution in the refrigeration circuit of the compressor is. Compared with the preferred embodiment, the alternative embodiment has the advantages that a frequency converter or a built-in frequency conversion module of the liquid pump can be omitted, the cost is saved, and the defects that the flow control precision of the main loop is poor and the liquid pump cannot realize low-frequency energy-saving operation are overcome.
According to the regulation control method, when the water chilling unit carries out natural cooling refrigeration, the set upper limit value of the heat exchange quantity of the outdoor heat exchanger group 3 is that the frequency conversion fan is increased to the set highest frequency, all the outdoor heat exchangers participate in work, the frequency conversion liquid pump is started to the rated frequency, the set lower limit value of the heat exchange quantity of the outdoor heat exchanger group 3 is that the water chilling unit enters a standby state, and the lowest load regulation range of the invention can reach the aim that
The adjustment accuracy is high and the applicable load demand range is wide.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (16)
1. The regulation control method of the water chilling unit comprises the following steps: the system comprises a compressor refrigeration loop and a natural cooling loop, wherein the compressor refrigeration loop is driven by a compressor to circulate refrigerant, the natural cooling loop is driven by a liquid pump to circulate refrigerating solution, and the natural cooling loop is provided with an outdoor heat exchanger group; the method is characterized by comprising the following steps:
judging whether the water chilling unit meets set natural cooling conditions or not;
if so, closing the compressor, starting the liquid pump, and exchanging heat between the refrigerating solution cooled by the outdoor heat exchanger group and the refrigerating water at the user side;
detecting the operation parameters of the water chilling unit;
and judging the load change of the water chilling unit according to the operation parameters and adjusting the heat exchange amount of the outdoor heat exchanger group.
2. The regulation control method of claim 1 wherein the operating parameter is an actual leaving water temperature after heat exchange of the chilled water.
3. The regulation control method according to claim 2, wherein judging the load change of the water chilling unit and regulating the heat exchange amount of the outdoor heat exchanger group according to the operation parameter comprises:
judging the interval of the actual outlet water temperature and executing a corresponding control strategy;
if the actual outlet water temperature T3-target outlet water temperature is larger than a first set value Ta continuously detected for T1 seconds, executing a load-increasing control strategy, and increasing the heat exchange quantity of the outdoor heat exchanger group;
and/or if the actual outlet water temperature T3-the target outlet water temperature is less than or equal to a second set value Tb is detected for T1 seconds continuously, executing a load reduction control strategy, and reducing the heat exchange amount of the outdoor heat exchanger group;
and/or if the second set value Tb is less than the actual outlet water temperature T3 and the target outlet water temperature is less than or equal to the first set value Ta, executing a maintenance control strategy and keeping the current running state of the water chilling unit unchanged.
4. The regulation and control method according to claim 3, wherein after the control strategy is executed each time, the set time is operated, the section where the actual outlet water temperature is located is continuously judged, and the corresponding control strategy is executed until the heat exchange amount of the outdoor heat exchanger group reaches a set upper limit value or a set lower limit value.
5. The regulation control method of any one of claims 1 to 4, wherein the outdoor heat exchanger group comprises at least two outdoor heat exchangers arranged in parallel; and the step of adjusting the heat exchange quantity of the outdoor heat exchanger group comprises adjusting the number of the outdoor heat exchangers participating in the work in the outdoor heat exchanger group.
6. The regulation and control method according to claim 5, wherein the outdoor heat exchangers in the outdoor heat exchanger group are provided with corresponding serial numbers according to the priority of opening, the opening sequence is from the outdoor heat exchanger with the smallest serial number to the outdoor heat exchanger with the largest serial number, and the closing sequence is from the outdoor heat exchanger with the largest serial number to the outdoor heat exchanger with the smallest serial number.
7. The regulation control method according to claim 5, wherein the number of the outdoor heat exchangers participating in the operation in the outdoor heat exchanger group is regulated each time, and is increased by 1 or decreased by 1.
8. The regulation and control method according to claim 5, wherein the outdoor heat exchanger which is firstly started in the outdoor heat exchanger group is a regulation heat exchanger which adopts a variable frequency fan;
and the step of adjusting the heat exchange quantity of the outdoor heat exchanger group further comprises adjusting the operating frequency of the variable frequency fan.
9. The regulation control method of claim 8, wherein the operating frequency of the variable frequency fan is adjusted each time only by increasing a set magnitude or decreasing a set magnitude.
10. The adjusting and controlling method according to claim 8, wherein when only the adjusting heat exchanger in the outdoor heat exchanger group is in operation, the number of the outdoor heat exchangers in the outdoor heat exchanger group in operation is increased after the operating frequency of the variable frequency fan is increased to a set maximum frequency.
11. The regulation control method according to claim 8, wherein when only the regulation heat exchanger in the outdoor heat exchanger group is in operation, the operation frequency of the variable frequency fan is reduced to be off, the liquid pump stops operating, and the water chilling unit enters a standby state.
12. The regulation control method of claim 5, wherein the regulating the heat exchange capacity of the group of outdoor heat exchangers further comprises regulating the flow of refrigerant solution in the free cooling circuit.
13. The regulation control method according to claim 12, wherein the liquid pump is a variable frequency liquid pump;
and the step of adjusting the flow of the refrigerating solution in the natural cooling loop comprises adjusting the operating frequency of the variable frequency liquid pump.
14. The regulation control method of claim 13, wherein the operating frequency of the variable frequency liquid pump is adjusted to (rated frequency ÷ n) × n1, n being the total number of outdoor heat exchangers in the outdoor heat exchanger group, and n1 being the number of outdoor heat exchangers in the outdoor heat exchanger group that are engaged in operation.
15. The regulation control method according to claim 12, wherein the liquid pump is a fixed-frequency liquid pump, a bypass circuit is connected to the liquid pump, the bypass circuit and the natural cooling circuit are connected in parallel, and a control valve with an adjustable opening degree is arranged in the bypass circuit.
16. Water chilling unit comprising a controller, characterized in that said controller controls the operating conditions of said water chilling unit using the regulation control method of any one of claims 1 to 15.
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| CN202011062459.6A CN112178873A (en) | 2020-09-30 | 2020-09-30 | Adjusting and controlling method of water chilling unit and water chilling unit |
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| CN202011062459.6A CN112178873A (en) | 2020-09-30 | 2020-09-30 | Adjusting and controlling method of water chilling unit and water chilling unit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113739463A (en) * | 2021-08-19 | 2021-12-03 | 珠海格力电器股份有限公司 | Control method and device for refrigerating unit and refrigerating equipment |
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