CN107560207B - Screw type water chilling unit and control method thereof - Google Patents
Screw type water chilling unit and control method thereof Download PDFInfo
- Publication number
- CN107560207B CN107560207B CN201710698031.2A CN201710698031A CN107560207B CN 107560207 B CN107560207 B CN 107560207B CN 201710698031 A CN201710698031 A CN 201710698031A CN 107560207 B CN107560207 B CN 107560207B
- Authority
- CN
- China
- Prior art keywords
- coolant
- water
- compressor
- refrigerant
- outlet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Abstract
The invention discloses a screw type water chilling unit and a control method thereof. The screw water chilling unit comprises a refrigerant circulation system and a refrigerant water circulation system, wherein the refrigerant circulation system comprises a compressor (1) and an evaporator (2), the refrigerant water circulation system comprises a refrigerant water inlet pipe (3), a refrigerant water outlet pipe (4) and a bypass pipe (5), the refrigerant water inlet pipe (3) is connected to a refrigerant water inlet of the evaporator (2), the refrigerant water outlet pipe (4) is connected to a refrigerant water outlet of the evaporator (2), a first end of the bypass pipe (5) is connected to the refrigerant water inlet pipe (3), a second end of the bypass pipe is connected to the refrigerant water outlet pipe (4), and the bypass pipe (5) is in heat exchange connection with exhaust gas of the compressor (1) through a heat exchange device (6). According to the screw type water chilling unit, the energy adjusting range of the unit can be widened, the low-load requirement of a user on a compressor is met, and the long-term stable operation of the unit under low load is ensured.
Description
Technical Field
The invention relates to the technical field of air conditioners, in particular to a screw type water chilling unit and a control method thereof.
Background
The prior screw type water chilling unit for the ship is mainly based on a fixed frequency type, and the energy adjusting mode of the screw type water chilling unit adopts a compressor slide valve for adjustment along with the change of load demands, and the basic principle is that the working volume between teeth of a female rotor and a male rotor of the compressor is still communicated with an air suction port within a period of time before a contact line between teeth moves from the air suction end to the air discharge end, so that part of air flows back to the air suction port, namely the effective working length of a screw is reduced, the purpose of energy adjustment is achieved, and the energy adjusting range is 20-100%.
Along with the improvement of customer demand, the customer is wider and wider to the load demand scope, has reached even 5%, and the demand of lower load to the customer has not been reached by compressor self slide valve energy adjustment, can only realize energy adjustment through the frequent start and stop of compressor, and this kind of mode can not only shorten the life of compressor and reduce the compressor reliability, and user's temperature fluctuation is great moreover, influences user's travelling comfort.
In addition, because marine screw water chilling unit is in order to prevent to incline and swing and cause the liquid problem of taking of breathing in, adopts dry evaporator, consequently screw compressor is from taking built-in oil content, still will have a small amount of oil to run into the system along with the compressor exhaust, and the compressor is long-term to be operated under low load, and the velocity of flow that breathes in is low, and the compressor is by the oil return difficulty of breathing in, and the shell and tube heat transfer area can be taken up to the oil deposit in the system, influences the heat transfer effect, and compressor oil leakage can lead to wearing and tearing such as bearing, rotor, reduces compressor life-span.
Disclosure of Invention
The embodiment of the invention provides a screw water chilling unit and a control method thereof, which can widen the energy adjustment range of the unit, meet the low-load requirement of a user on a compressor and ensure the long-term stable operation of the unit under low load.
In order to achieve the above object, an embodiment of the present invention provides a screw water chiller, including a refrigerant circulation system and a refrigerant water circulation system, the refrigerant circulation system includes a compressor and an evaporator, the refrigerant water circulation system includes a refrigerant water inlet pipe, a refrigerant water outlet pipe and a bypass pipe, the refrigerant water inlet pipe is connected to a refrigerant water inlet of the evaporator, the refrigerant water outlet pipe is connected to a refrigerant water outlet of the evaporator, a first end of the bypass pipe is connected to the refrigerant water inlet pipe, a second end is connected to the refrigerant water outlet pipe, and the bypass pipe is connected to an exhaust gas of the compressor through heat exchange of a heat exchange device.
Preferably, the bypass pipe is provided with a flow rate regulating valve.
Preferably, the coolant water inlet pipe and/or the coolant water outlet pipe are/is provided with a three-way valve, and the second end of the bypass pipe is connected to the three-way valve and is used for flow regulation through the three-way valve.
Preferably, the three-way valve is an electric three-way valve.
Preferably, the evaporator is a dry evaporator; and/or the refrigerant cycle system further comprises a condenser, wherein the condenser is a flooded condenser.
Preferably, the heat exchange device is a plate heat exchanger.
Preferably, a refrigerant water pump is arranged on the refrigerant water inlet pipe; and/or the cool water inlet of the evaporator is provided with a cool water inlet temperature sensing bulb, and the cool water outlet of the evaporator is provided with a cool water outlet temperature sensing bulb.
Preferably, the bypass pipe is provided with a control valve for controlling the on-off of the bypass pipe.
According to another aspect of the present invention, there is provided a control method of a screw water chiller, including:
acquiring a return water temperature Tyi of the refrigerant water;
acquiring a chilled water outlet temperature set value To;
acquiring a water temperature difference set value delta T of coolant water inlet and outlet;
the flow rate of the refrigerant water reaching the refrigerant water inlet pipe from the refrigerant water outlet pipe through the bypass pipe is regulated according To the relation among the refrigerant water return temperature Tyi, the refrigerant water outlet temperature set value To and the refrigerant water inlet and outlet temperature difference set value DeltaT.
Preferably, before the step of adjusting the flow rate of the coolant flowing from the coolant outlet pipe To the coolant inlet pipe through the bypass pipe according To the relationship among the coolant return water temperature Tyi, the coolant outlet water temperature set value To, and the coolant inlet and outlet water temperature difference set value Δt, the method further comprises:
after the screw water chilling unit is electrified, before the compressor is started, the flow regulating valve for controlling the flow of the refrigerant water is reset, and then the flow regulating valve is opened to an initial opening degree.
Preferably, the step of opening the flow rate adjustment valve to an initial opening degree includes:
acquiring a coolant water inlet temperature Tin;
when Tin is more than or equal To To+a delta T, controlling the initial opening of the flow regulating valve To be 0%;
when Tin is less than to+a delta T, controlling the initial opening of the flow regulating valve To be b%;
where a is greater than or equal to the percentage of the unit's lowest operating load relative to the unit's capacity at full load.
Preferably, a is 30% and b is 20.
Preferably, the step of adjusting the flow rate of the coolant flowing from the coolant outlet pipe To the coolant inlet pipe through the bypass pipe according To the relationship among the coolant return water temperature Tyi, the coolant outlet water temperature set value To, and the coolant inlet and outlet water temperature difference set value Δt includes:
obtaining a coolant water outlet temperature Tout;
when Tyi-Tout is detected to be more than or equal to a delta T in the continuous T1 time, if the flow regulating valve is not fully closed, closing the opening of the flow regulating valve to be fully closed according to the step frequency of c% of closing every T2 time, and running the compressor according to capability deviation;
when D delta T is less than or equal To Tyi-Tout and less than a delta T is detected in the continuous T3 time, the target condensate water inlet temperature Ti=to+a delta T is obtained, the opening of the flow regulating valve is controlled To act according To the opening increment D, and the compressor operates according To the capacity deviation;
when Tyi-Tout < d delta T is detected in the continuous T4 time, closing the opening of the flow regulating valve to be fully closed according to the step frequency of closing e% in each T5 time, and controlling the compressor according to the standby condition;
wherein D is smaller than the percentage of the lowest running load of the unit relative to the capacity of the unit when the unit is fully loaded, and D is determined according to the target water inlet temperature Ti of condensed water and the water inlet temperature Tin of cooling water.
Preferably, t1 is 2min, t2 is 4s, c is 2.0, t3 is 1min, d is 10%, t4 is 2min, t5 is 4s, e is 2.0.
Preferably, before the step of adjusting the flow rate of the coolant flowing from the coolant outlet pipe To the coolant inlet pipe through the bypass pipe according To the relationship among the coolant return water temperature Tyi, the coolant outlet water temperature set value To, and the coolant inlet and outlet water temperature difference set value Δt, the method further comprises:
determining the capacity deviation B of the compressor according To the refrigerant water outlet temperature set value To and the refrigerant water outlet temperature Tout;
when B is more than or equal to the dead zone, the compressor is loaded and operated;
when the dead zone is less than B and less than the dead zone, the compressor keeps running;
and when B is less than or equal to the dead zone, the compressor is unloaded and operated.
Preferably, when the calculated absolute value of the opening increment of the flow rate adjustment valve is greater than 5%, 5% is used as the opening increment of the flow rate adjustment valve, and the flow rate adjustment valve is controlled to operate once every t6 time.
Preferably, the control method of the screw water chiller further comprises:
determining the actual capacity A of the compressor according to the position of a slide valve of the compressor;
detecting accumulated running time of the compressor under the condition that the actual capacity A is less than or equal to f and continuously running time of the compressor under the condition that the actual capacity A is more than f in a t6 time period of accumulated running of the compressor;
if the accumulated running time of the compressor is greater than t7 under the condition that the actual capacity A is less than or equal to f and the continuous running time of the compressor is less than t8 under the condition that the actual capacity A is more than f, controlling the compressor to perform oil return running t9, and re-timing after oil return is finished;
if the conditions are not met, the compressor does not perform oil return control, and the time is counted again after the running is accumulated for a time of t6, wherein f ranges from 70% to 80%.
Preferably, when the compressor performs oil return control, the target inflow temperature ti=the set value To of the inflow temperature of the coolant and the set value Δt of the inflow temperature difference of the coolant, the opening of the flow rate adjusting valve is controlled To act according To the opening increment D of the flow rate adjusting valve, and the compressor is controlled To operate according To the capacity deviation B, wherein D is determined according To the target inflow temperature Ti of the condensate water and the inflow temperature Tin of the coolant, and B is determined according To the set value To of the outflow temperature of the coolant and the outflow temperature Tout of the coolant.
Preferably, f is 75%, t6 is 12h, t7 is 6h, t8 is 1.5h, and t9 is 1.5h.
By applying the technical scheme of the invention, the screw water chilling unit comprises a refrigerant circulation system and a refrigerant water circulation system, the refrigerant circulation system comprises a compressor and an evaporator, the refrigerant water circulation system comprises a refrigerant water inlet pipe, a refrigerant water outlet pipe and a bypass pipe, the refrigerant water inlet pipe is connected to a refrigerant water inlet of the evaporator, the refrigerant water outlet pipe is connected to a refrigerant water outlet of the evaporator, a first end of the bypass pipe is connected to the refrigerant water inlet pipe, a second end of the bypass pipe is connected to the refrigerant water outlet pipe, and the bypass pipe is in heat exchange connection with exhaust gas of the compressor through a heat exchange device. According to the invention, the screw type water chilling unit is additionally provided with the heat exchange device, and the high-temperature exhaust of the screw compressor and the water way of the coolant bypass pipe are utilized for heat exchange, so that coolant at the coolant outlet enters the coolant inlet after heat exchange with the exhaust of the compressor through the bypass pipe, the coolant inlet temperature of the evaporator is regulated, the requirement of the unit on running under lower load is met, the energy regulation range of the unit is widened, the requirement of customers on lower load is met, and long-term stable running of the unit under low load is ensured.
Drawings
FIG. 1 is a schematic diagram of a screw chiller according to an embodiment of the present invention;
FIG. 2 is a control schematic diagram of a screw chiller according to an embodiment of the present invention;
fig. 3 is a control flow chart of the screw chiller according to an embodiment of the present invention.
Reference numerals illustrate: 1. a compressor; 2. an evaporator; 3. a coolant water inlet pipe; 4. a coolant water outlet pipe; 5. a bypass pipe; 6. a heat exchange device; 7. an electric three-way valve; 8. a condenser; 9. a refrigerant water pump; 10. a cooling water inflow temperature sensing bag; 11. a chilled water outlet temperature sensing bulb; 12. a control valve; 13. a chilled water backwater temperature sensing bag; 14. a throttle device; 15. and (5) drying the filter.
Detailed Description
The invention will now be described in further detail with reference to the drawings and specific examples, which are not intended to limit the invention thereto.
Referring to fig. 1 and 2 in combination, according to an embodiment of the present invention, a screw type water chiller includes a refrigerant circulation system including a compressor 1 and an evaporator 2, and a coolant circulation system including a coolant inlet pipe 3, a coolant outlet pipe 4, and a bypass pipe 5, the coolant inlet pipe 3 being connected to a coolant inlet of the evaporator 2, the coolant outlet pipe 4 being connected to a coolant outlet of the evaporator 2, a first end of the bypass pipe 5 being connected to the coolant inlet pipe 3, a second end being connected to the coolant outlet pipe 4, the bypass pipe 5 being heat-exchanged with an exhaust gas of the compressor 1 through a heat exchange device 6.
In the invention, the screw type water chilling unit is additionally provided with the heat exchange device 6, and the high-temperature exhaust of the screw compressor and the water way of the coolant bypass pipe are utilized for heat exchange, so that coolant at the coolant outlet enters the coolant inlet after heat exchange with the exhaust of the compressor through the bypass pipe 5, the coolant inlet temperature of the evaporator 2 is regulated, the requirement of the unit on running under lower load is met, the energy regulation range of the unit is widened, the requirement of customers on lower load is met, and the long-term stable running of the unit under low load is ensured.
Preferably, the evaporator 2 is a dry evaporator, thereby preventing the evaporator 2 from tilting and rocking to cause the compressor suction liquid carrying problem.
Preferably, the refrigerant cycle system further comprises a condenser 8, the condenser 8 being a flooded condenser.
The refrigerant circulation system further comprises a ball valve, and the ball valves are arranged at the outlet end of the condenser and the inlet end of the evaporator.
Between the condenser 8 and the evaporator 2 there is also provided a throttle device 14, for example a thermostatic expansion valve.
A dry filter 15 for dry-filtering the refrigerant is further provided between the condenser 8 and the throttle device 14.
In order to better match the coolant flow rate of the bypass pipe with the load of the unit, the flow rate of the coolant flowing to the coolant inlet pipe 3 through the bypass pipe is preferably adjustable.
In one embodiment, the bypass pipe 5 is provided with a flow regulating valve, and the opening of the flow regulating valve is regulated to flexibly regulate the coolant flow of the bypass pipe 5, so that the energy regulating range of the unit can be better widened.
In another embodiment, the coolant water inlet pipe 3 and/or the coolant water outlet pipe 4 are provided with a three-way valve, and the second end of the bypass pipe 5 is connected to the three-way valve and performs flow adjustment through the three-way valve. Under the condition, the flow of the coolant can be regulated at the connection position of the coolant outlet pipe 4 and the bypass pipe 5 or the connection position of the coolant inlet pipe 3 and the bypass pipe 5, so that the flow of the coolant can be better matched with the required running load of the unit, and the low-load running of the unit can be better realized on the basis of saving energy.
Preferably, the three-way valve is an electric three-way valve 7, the opening of the electric three-way valve 7 can be adjusted through electric power, the adjustment is more accurate, the control is more sensitive and reliable, and the automatic control can be realized.
Preferably, the heat exchange means 6 is a plate heat exchanger. The plate heat exchanger has simple structure and lower cost, can conveniently realize the heat exchange between the refrigerant water in the bypass pipe 5 and the exhaust gas of the compressor 1, and has higher heat exchange efficiency.
Preferably, the refrigerant water inlet pipe 3 is provided with a refrigerant water pump 9; and/or the chilled water inlet of the evaporator 2 is provided with a chilled water inlet temperature sensing bulb 10, and the chilled water outlet of the evaporator 2 is provided with a chilled water outlet temperature sensing bulb 11. The coolant pump 9 can provide power for the flow of coolant water, so that the coolant water can smoothly flow, and the utilization and recovery of the coolant water are realized.
The user backwater end of the chilled water circulation system is also provided with a chilled water backwater temperature sensing bulb 13 for detecting the backwater temperature of chilled water.
The plate heat exchanger is added between the compressor and the condenser to serve as a heat recovery device, the evaporator water is bypassed to the plate heat exchanger and the compressor to exchange heat with high-temperature exhaust gas, the mixture is fed into the evaporator by the refrigerant water pump after being mixed with user backwater through the electric three-way valve, the opening of the electric three-way valve is controlled through the PID algorithm to regulate the bypass water flow of the refrigerant water so as to control the water inlet temperature of the evaporator, the variable virtual user load requirement is increased additionally, the screw compressor always operates above a certain limited minimum capacity, the capacity that the screw compressor does not unload to lower load operation is solved while the low load requirement of a real user is ensured, and in addition, the heat of the compressor high-temperature exhaust gas is recovered by the plate heat exchanger without providing an additional heat source, so that the heat load of the condenser is reduced. The minimum capacity defined is the minimum capacity of the compressor for reliable and safe operation, and the minimum refrigerating capacity of the compressor is generally more than 30% because the screw compressor cools the motor by suction, the suction flow is small under low load, the heating of the motor is insufficient to cool, and the temperature of the motor is continuously increased, so that the minimum refrigerating capacity of the compressor is limited to be near the minimum value for ensuring the motor to safely operate.
Preferably, the bypass pipe 5 is provided with a control valve 12 for controlling the on-off of the bypass pipe 5. The control valve 12 is used for closing the bypass pipe 5 under the condition that the compressor can meet the low-load operation, so that the load adjustment is carried out through the compressor 1, and the control difficulty of the refrigerating unit is reduced.
The control system of the screw type water chilling unit comprises a main control processing unit, a coolant water return temperature sensing bulb, a coolant water inlet temperature sensing bulb, a coolant water outlet temperature sensing bulb and a slide valve position detection module, wherein the coolant water return temperature sensing bulb, the coolant water inlet temperature sensing bulb, the coolant water outlet temperature sensing bulb and the slide valve position detection module are all electrically connected to the main control processing unit, after the main control processing unit receives data of the units, the main control processing unit processes the data, then the feedback information of the electric three-way valve is combined to control the electric three-way valve, and meanwhile, the loading electromagnetic valve and the unloading electromagnetic valve of the compressor are controlled according to the data processing result, so that the loading or unloading operation of the compressor is realized.
Preferably, the screw water chilling unit is a marine screw water chilling unit.
Referring to fig. 3 in combination, according to an embodiment of the present invention, a control method of a screw water chiller includes: acquiring a return water temperature Tyi of the refrigerant water; acquiring a chilled water outlet temperature set value To; acquiring a water temperature difference set value delta T of coolant water inlet and outlet; the flow rate of the refrigerant water reaching the refrigerant water inlet pipe 3 from the refrigerant water outlet pipe 4 through the bypass pipe 5 is regulated according To the relation among the refrigerant water return temperature Tyi, the refrigerant water outlet temperature set value To and the refrigerant water inlet and outlet temperature difference set value DeltaT. By the control method, whether the required load of the compressor is in the lowest load range of the compressor can be determined by combining the chilled water return temperature, the chilled water outlet temperature set value and the chilled water inlet and outlet temperature difference set value, if the load is in the lowest load range of the compressor, the control is directly performed through the compressor, and if the load exceeds the lowest load range adjustable by the compressor, the lowest load of the unit needs to be adjusted by means of the bypass pipe 5, so that the stable operation of the lower unit load can be realized.
In addition, the hydraulic losses of the refrigerant water bypass pipeline and the user parallel pipeline are subjected to resistance balance calculation, and the flow of the refrigerant water bypass water is controlled within a certain range by changing the pipe diameter of the bypass pipeline and locally adding a valve.
Preferably, before the step of adjusting the flow rate of the refrigerant water reaching the refrigerant water inlet pipe 3 from the refrigerant water outlet pipe 4 through the bypass pipe 5 according To the relationship among the refrigerant water return temperature Tyi, the refrigerant water outlet temperature set value To and the refrigerant water inlet and outlet temperature difference set value Δt, the method further comprises:
after the screw water chilling unit is electrified, before the compressor 1 is started, the flow regulating valve for controlling the flow of the refrigerant water is reset, and then the flow regulating valve is opened to an initial opening degree. Taking an electric three-way valve as an example, the electric three-way valve controls input and output through a 4-20 mA current signal, wherein the opening degree of the electric three-way valve is 0% to indicate that the bypass water flow of the refrigerant water is 0, and the opening degree of the electric three-way valve is 100% to indicate that the bypass water flow of the refrigerant water reaches the maximum value. After the unit is electrified for the first time, the reset action of the electric three-way valve is finished before the compressor is started: first to 100%, then to 0%, then to the initial opening degree.
Preferably, the step of opening the flow rate adjustment valve to the initial opening degree includes:
acquiring a coolant water inlet temperature Tin; when Tin is more than or equal To To+a delta T, controlling the initial opening of the flow regulating valve To be 0%; when Tin is less than to+a delta T, controlling the initial opening of the flow regulating valve To be b%; where a is greater than or equal to the percentage of the unit's lowest operating load relative to the unit's capacity at full load.
Preferably, a is 30% and b is 20.
The set value DeltaT of the temperature difference of the coolant water inlet and outlet represents the temperature difference of the coolant water inlet and outlet when the unit is fully loaded, the value a is 30 percent, which represents that the current required load is 30 percent of the capacity of the unit when the unit is fully loaded, and the capacity of the compressor is adjusted by 30 percent of the full load of the unit, so that the unit is not required To be adjusted by a flow regulating valve, when Tin is more than or equal To To+aDeltaT, the running requirement of the unit can be met by the self-adjustment of the compressor, and at the moment, the bypass pipe 5 is not required To be communicated, and the initial opening of the flow regulating valve is 0 percent.
When Tin < to+a delta T, the lowest operation load of the unit exceeds the lowest load adjusting range of the compressor, so that the minimum load operation of the unit needs To be realized by means of the bypass pipe, and therefore, the initial opening degree of the flow regulating valve needs To be 20%, so that the refrigerant water in the bypass pipe can flow into the refrigerant water inlet pipe 3, and the unit is operated at the lowest load together with the compressor.
Preferably, the step of adjusting the flow rate of the coolant flowing from the coolant outlet pipe 4 To the coolant inlet pipe 3 through the bypass pipe 5 according To the relationship among the coolant return water temperature Tyi, the coolant outlet water temperature set value To, and the coolant inlet and outlet water temperature difference set value Δt includes:
obtaining a coolant water outlet temperature Tout; when Tyi-Tout is detected to be more than or equal to a delta T in the continuous T1 time, if the flow regulating valve is not fully closed, closing the opening of the flow regulating valve to be fully closed according to the step frequency of c% of closing every T2 time, and running the compressor 1 according to capability deviation; when D delta T is less than or equal To Tyi-Tout and less than a delta T is detected in the continuous T3 time, the target condensate water inlet temperature Ti=to+a delta T is obtained, the opening of the flow regulating valve is controlled To act according To the opening increment D, and the compressor 1 operates according To the capacity deviation; when Tyi-Tout < d delta T is detected in the continuous T4 time, the opening of the flow regulating valve is closed to be fully closed according to the step frequency of closing e% in every T5 time, and the compressor 1 is controlled according to the standby condition; and D is smaller than the percentage of the lowest running load of the unit relative to the capacity of the unit when the unit is fully loaded, and is determined by proportional and integral calculation according to the target water inlet temperature Ti of condensed water and the water inlet temperature Tin of the refrigerant water.
Preferably, t1 is 2min, t2 is 4s, c is 2.0, t3 is 1min, d is 10%, t4 is 2min, t5 is 4s, e is 2.0.
The load demand below 10% has reached the capacity limit for the unit, even if the load is adjusted by means of the flow control valve, it is meaningless, and the fluctuation of the water temperature of 10% has little effect on the user, so that the unit is not turned on any more, and therefore is put into standby at this time.
Preferably, before the step of adjusting the flow rate of the refrigerant water reaching the refrigerant water inlet pipe 3 from the refrigerant water outlet pipe 4 through the bypass pipe 5 according To the relationship among the refrigerant water return temperature Tyi, the refrigerant water outlet temperature set value To and the refrigerant water inlet and outlet temperature difference set value Δt, the method further comprises:
determining the capacity deviation B of the compressor 1 according To the refrigerant water outlet temperature set value To and the refrigerant water outlet temperature Tout; when B is more than or equal to the dead zone, the compressor 1 is loaded and operated, namely, the electromagnetic valve is loaded to obtain electricity; when the dead zone is smaller than B and smaller than the dead zone, the compressor 1 keeps running, namely the loading and unloading electromagnetic valves are all powered off; and when B is less than or equal to the-dead zone, the compressor 1 is unloaded and operated, namely the unloading electromagnetic valve is powered. The capacity deviation B is a deviation value of actual capacity and target capacity of the compressor, is a percentage, and is used for controlling the compressor to perform capacity adjustment operation according to the capacity deviation, and the calculation method is to perform proportional and integral calculation according to the water temperature deviation. The dead zone refers to an action range of the compressor for energy adjustment, which is a percentage of the capacity of the compressor, and the energy adjustment of the compressor is based on the capacity deviation and the dead zone.
The opening increment calculation of the flow valve is not performed from the start of the compressor to the operation according to the capacity deviation B, and the corresponding control is performed according to the temperature of each position of the refrigerant water after the operation according to the capacity deviation. The start-up process of the compressor is an unstable process for the system, and if the flow regulating valve is operated again, the system can be caused to fluctuate more, the compressor is stable after being operated according to the capacity deviation, and the flow regulating valve can be regulated relatively stably at the time.
Preferably, when the calculated absolute value of the opening increment of the flow rate adjustment valve is greater than 5%, 5% is taken as the opening increment of the flow rate adjustment valve, and the flow rate adjustment valve is controlled to operate once every t10 time. Because the opening increment of the flow regulating valve is calculated according to the water temperature deviation, the action step is too large, and the water temperature can possibly run over to fluctuate, so that 5% is taken as a boundary point of the opening increment, and the stable regulation of the flow regulating valve is ensured. the time setting of t10 ensures that the flow regulating valve operates stably.
The marine screw type water chilling unit adopts the dry evaporator, and the screw compressor has built-in oil content, but a small amount of refrigerating oil still enters the system along with the exhaust of the compressor, and particularly, the unit runs under low load for a long time, the circulation flow of the refrigerant is small, the flow rate of the return air pipe of the compressor is low, and the refrigerating oil is difficult to be brought back to the compressor, so that the refrigerating oil is brought back to the compressor by utilizing the high flow rate return air after the compressor runs under full load in the scheme, and the low-load requirement of a user is met.
Specifically, in this embodiment, the control method of the screw water chiller further includes:
determining the actual capacity a of the compressor 1 from the position of the slide valve of the compressor 1; detecting the accumulated running time of the compressor 1 under the condition that the actual capacity A is less than or equal to f and the continuous running time of the compressor 1 under the condition that the actual capacity A is more than or equal to f in the t6 time period of the accumulated running of the compressor 1; if the accumulated running time of the compressor 1 is greater than t7 under the condition that the actual capacity A is less than or equal to f, and the continuous running time of the compressor 1 is less than t8 under the condition that the actual capacity A is more than f, controlling the compressor 1 to perform oil return running t9, and re-timing after oil return is finished; if the above conditions are not satisfied, the compressor 1 does not perform oil return control, and the time is counted again after the accumulated operation is full of t6, wherein f is 70% to 80%. Converting the position of the slide valve into an analog signal, and feeding the analog signal back to a control system, and judging the actual capacity A of the compressor according to the value of the analog signal; the actual capacity a of the compressor is the capacity of the compressor at the current slide valve position.
Preferably, when the compressor 1 performs oil return control, the target inflow water temperature ti=the set inflow water temperature to+the set inflow water temperature To/outflow water temperature difference Δt, the opening of the flow rate adjusting valve is controlled To act according To the opening increment D of the flow rate adjusting valve, and the compressor 1 is controlled To operate according To the capacity deviation B, wherein D is determined according To the target inflow water temperature Ti of the condensed water and the inflow water temperature Tin of the condensed water, and B is determined according To the set inflow water temperature To of the refrigerant and the outflow water temperature Tout of the refrigerant.
Preferably, f is 75%, t6 is 12h, t7 is 6h, t8 is 1.5h, and t9 is 1.5h.
Of course, the above is a preferred embodiment of the present invention. It should be noted that it will be apparent to those skilled in the art that several modifications and adaptations can be made without departing from the general principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.
Claims (17)
1. The control method of the screw type water chilling unit comprises a refrigerant circulation system and a refrigerant water circulation system, wherein the refrigerant circulation system comprises a compressor (1) and an evaporator (2), the refrigerant water circulation system comprises a refrigerant water inlet pipe (3), a refrigerant water outlet pipe (4) and a bypass pipe (5), the refrigerant water inlet pipe (3) is connected to a refrigerant water inlet of the evaporator (2), the refrigerant water outlet pipe (4) is connected to a refrigerant water outlet of the evaporator (2), a first end of the bypass pipe (5) is connected to the refrigerant water inlet pipe (3), a second end of the bypass pipe is connected to the refrigerant water outlet pipe (4), and the bypass pipe (5) is in heat exchange connection with exhaust gas of the compressor (1) through a heat exchange device (6);
the control method of the screw water chilling unit comprises the following steps:
acquiring a return water temperature Tyi of the refrigerant water;
acquiring a chilled water outlet temperature set value To;
acquiring a water temperature difference set value delta T of coolant water inlet and outlet;
according To the relation among the return water temperature Tyi of the coolant, the set value To of the outlet water temperature of the coolant and the set value delta T of the inlet and outlet water temperature difference of the coolant, the flow rate of the coolant reaching the inlet pipe (3) of the coolant from the coolant outlet pipe (4) through the bypass pipe (5) is regulated;
the step of adjusting the coolant flow from the coolant outlet pipe (4) To the coolant inlet pipe (3) through the bypass pipe (5) according To the relation among the coolant return water temperature Tyi, the coolant outlet water temperature set value To and the coolant inlet and outlet water temperature difference set value DeltaT comprises the following steps:
obtaining a coolant water outlet temperature Tout;
when Tyi-Tout is detected to be more than or equal to a delta T in the continuous T1 time, if the flow regulating valve is not fully closed, closing the opening of the flow regulating valve to be fully closed according to the step frequency of c% of closing every T2 time, and operating the compressor (1) according to the capacity deviation;
when D delta T is detected To be less than or equal To Tyi-Tout and less than a delta T in a continuous T3 time, the target inflow temperature Ti=to+a delta T of the chilled water is detected, the opening of the flow regulating valve is controlled To act according To the opening increment D, and the compressor (1) is operated according To the capacity deviation;
when Tyi-Tout < d delta T is detected in the continuous T4 time, the opening of the flow regulating valve is closed to be fully closed according to the step frequency of closing e% in every T5 time, and the compressor (1) is controlled according to the standby condition;
wherein D is smaller than the percentage of the lowest running load of the unit relative to the capacity of the unit when the unit is fully loaded, and D is determined according to the target water inlet temperature Ti of the coolant and the water inlet temperature Tin of the coolant.
2. The control method of a screw chiller according to claim 1, characterized in that a flow regulating valve is provided on the bypass pipe (5) of the screw chiller.
3. The control method of a screw water chiller according to claim 1, characterized in that a three-way valve is arranged on the chilled water inlet pipe (3) and/or the chilled water outlet pipe (4) of the screw water chiller, and the second end of the bypass pipe (5) is connected to the three-way valve and is used for flow regulation through the three-way valve.
4. A control method of a screw chiller according to claim 3 characterised in that the three-way valve of the screw chiller is an electric three-way valve (7).
5. The control method of a screw chiller according to claim 1, characterized in that the evaporator (2) of the screw chiller is a dry evaporator; and/or, the refrigerant cycle system further comprises a condenser (8), wherein the condenser (8) is a flooded condenser.
6. The control method of a screw chiller according to any of claims 1 to 5 wherein the heat exchange device (6) of the screw chiller is a plate heat exchanger.
7. The control method of a screw chiller according to any of claims 1 to 5, characterized in that a chilled water pump (9) is provided on the chilled water inlet pipe (3) of the screw chiller; and/or a chilled water inlet temperature sensing bulb (10) is arranged at the chilled water inlet of the evaporator (2), and a chilled water outlet temperature sensing bulb (11) is arranged at the chilled water outlet of the evaporator (2).
8. The control method of a screw water chiller according to any of claims 1 to 5, characterized in that a control valve (12) for controlling the on-off of the bypass pipe (5) is provided on the bypass pipe (5) of the screw water chiller.
9. The control method of a screw water chiller according To claim 1, wherein the step of adjusting the flow rate of the coolant water from the coolant outlet pipe (4) To the coolant inlet pipe (3) through the bypass pipe (5) according To the relationship among the coolant return water temperature Tyi, the coolant outlet water temperature set value To, and the coolant inlet and outlet water temperature difference set value Δt further comprises:
after the screw water chilling unit is electrified, before the compressor (1) is started, the flow regulating valve for controlling the flow of the refrigerant water is reset, and then the flow regulating valve is opened to an initial opening degree.
10. The control method of a screw chiller according to claim 9 wherein the step of opening the flow regulator valve to an initial opening degree comprises:
acquiring a coolant water inlet temperature Tin;
when Tin is more than or equal To To+a delta T, controlling the initial opening of the flow regulating valve To be 0%;
when Tin is less than to+a delta T, controlling the initial opening of the flow regulating valve To be b%;
where a is greater than or equal to the percentage of the unit's lowest operating load relative to the unit's capacity at full load.
11. The control method of a screw chiller according to claim 10 wherein a is 30% and b is 20.
12. The control method of a screw chiller according to claim 1 wherein t1 is 2min, t2 is 4s, c is 2.0, t3 is 1min, d is 10%, t4 is 2min, t5 is 4s, and e is 2.0.
13. The control method of a screw water chiller according To claim 1, wherein the step of adjusting the flow rate of the coolant water from the coolant outlet pipe (4) To the coolant inlet pipe (3) through the bypass pipe (5) according To the relationship among the coolant return water temperature Tyi, the coolant outlet water temperature set value To, and the coolant inlet and outlet water temperature difference set value Δt further comprises:
determining the capacity deviation B of the compressor (1) according To the refrigerant water outlet temperature set value To and the refrigerant water outlet temperature Tout;
when B is more than or equal to the dead zone, the compressor (1) is loaded and operated;
when the dead zone is less than B and less than the dead zone, the compressor (1) keeps running;
and when B is less than or equal to the dead zone, the compressor (1) is unloaded and operated.
14. The control method of a screw chiller according to claim 13 wherein when the calculated absolute value of the opening increment of the flow rate control valve is greater than 5%, the opening increment of the flow rate control valve is set to 5% and the flow rate control valve is controlled to operate once every t10 times.
15. The control method of a screw chiller according to claim 1, further comprising:
determining an actual capacity A of the compressor (1) based on the position of the slide valve of the compressor (1);
detecting the accumulated running time of the compressor (1) in a t6 time period of the accumulated running of the compressor (1) under the condition that the actual capacity A is less than or equal to f, and continuously running the compressor (1) under the condition that the actual capacity A is more than f;
if the accumulated running time of the compressor (1) is greater than t7 under the condition that the actual capacity A is less than or equal to f, and the continuous running time of the compressor (1) is less than t8 under the condition that the actual capacity A is more than f, controlling the compressor (1) to perform oil return running for t9 time, and re-timing after oil return is finished;
if the conditions are not met, the compressor (1) does not perform oil return control, and the time is counted again after the accumulated running is full of t6, wherein f ranges from 70% to 80%.
16. The control method of a screw chiller according To claim 15 wherein, when the compressor (1) performs oil return control, the target inlet water temperature Ti of the coolant is=the outlet water temperature set value To of the coolant+the inlet and outlet water temperature difference set value Δt of the coolant, the opening of the flow rate regulating valve is controlled To act according To the opening increment D of the flow rate regulating valve, and the compressor (1) is controlled To operate according To the capacity deviation B, wherein D is determined according To the target inlet water temperature Ti of the coolant and the inlet water temperature Tin of the coolant, and B is determined according To the outlet water temperature set value To of the coolant and the outlet water temperature Tout of the coolant.
17. The method of claim 15, wherein f is 75%, t6 is 12h, t7 is 6h, t8 is 1.5h, and t9 is 1.5h.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710698031.2A CN107560207B (en) | 2017-08-15 | 2017-08-15 | Screw type water chilling unit and control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710698031.2A CN107560207B (en) | 2017-08-15 | 2017-08-15 | Screw type water chilling unit and control method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107560207A CN107560207A (en) | 2018-01-09 |
| CN107560207B true CN107560207B (en) | 2023-09-12 |
Family
ID=60975513
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710698031.2A Active CN107560207B (en) | 2017-08-15 | 2017-08-15 | Screw type water chilling unit and control method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107560207B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108662798A (en) * | 2018-06-21 | 2018-10-16 | 珠海格力电器股份有限公司 | A kind of handpiece Water Chilling Units and its control method, device |
| CN109631376B (en) * | 2018-11-27 | 2022-01-28 | 珠海格力电器股份有限公司 | Screw type water chilling unit and control method and system thereof |
| CN109915951A (en) * | 2019-02-25 | 2019-06-21 | 珠海格力电器股份有限公司 | Unit and control method are adjusted with 0 ~ 100% output load regulating power center air |
| CN109916111A (en) * | 2019-04-01 | 2019-06-21 | 珠海格力电器股份有限公司 | Chilled water is mixed to the air-conditioner set and its control method for reducing temperature with cooling water |
| CN110243097B (en) * | 2019-06-19 | 2023-08-18 | 珠海格力电器股份有限公司 | Machine tool cooling unit and control method thereof |
| CN112856724B (en) * | 2021-01-07 | 2022-07-12 | 丁一 | Control method, device and system of water chilling unit |
| CN113483385B (en) * | 2021-07-02 | 2022-10-04 | 青岛海信日立空调系统有限公司 | Air source heat pump unit |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4802338A (en) * | 1986-04-25 | 1989-02-07 | Advantage Engineering Incorporated | Precision-controlled water chiller |
| JPH03225148A (en) * | 1990-01-31 | 1991-10-04 | Nippondenso Co Ltd | Air conditioner |
| JP2001263837A (en) * | 2000-03-23 | 2001-09-26 | Daikin Ind Ltd | Refrigerating circuit |
| CN1888614A (en) * | 2006-07-13 | 2007-01-03 | 上海交通大学 | Energy-saving central air conditioner |
| CN102193567A (en) * | 2010-03-10 | 2011-09-21 | 同方人工环境有限公司 | Method for controlling stepless adjustment of water-source screw unit |
| CN102616364A (en) * | 2011-01-29 | 2012-08-01 | 珠海格力电器股份有限公司 | Marine seawater source heat pump air-conditioning system |
| CN103206814A (en) * | 2013-04-12 | 2013-07-17 | 南京佳力图空调机电有限公司 | Supercooling device for magnetic suspension refrigerating system with natural cold source |
| WO2016058280A1 (en) * | 2014-10-16 | 2016-04-21 | 中国扬子集团滁州扬子空调器有限公司 | Combined cascade refrigeration air-conditioning system and control method therefor |
| CN106246550A (en) * | 2016-09-08 | 2016-12-21 | 珠海格力电器股份有限公司 | Control device, control method and the compressor of a kind of guiding valve |
| CN106440546A (en) * | 2016-09-05 | 2017-02-22 | 珠海格力电器股份有限公司 | Chilled water way system, adjusting method of system, water chilling unit and air conditioner |
| CN206291546U (en) * | 2016-12-26 | 2017-06-30 | 珠海华隆科技有限公司 | The water-cooling device of temperature control is carried out using magnetic valve bypass waterway |
| CN207196987U (en) * | 2017-08-15 | 2018-04-06 | 珠海格力电器股份有限公司 | Screw-type water chiller |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5375945B2 (en) * | 2011-12-28 | 2013-12-25 | ダイキン工業株式会社 | Air conditioning system that adjusts temperature and humidity |
-
2017
- 2017-08-15 CN CN201710698031.2A patent/CN107560207B/en active Active
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4802338A (en) * | 1986-04-25 | 1989-02-07 | Advantage Engineering Incorporated | Precision-controlled water chiller |
| JPH03225148A (en) * | 1990-01-31 | 1991-10-04 | Nippondenso Co Ltd | Air conditioner |
| JP2001263837A (en) * | 2000-03-23 | 2001-09-26 | Daikin Ind Ltd | Refrigerating circuit |
| CN1888614A (en) * | 2006-07-13 | 2007-01-03 | 上海交通大学 | Energy-saving central air conditioner |
| CN102193567A (en) * | 2010-03-10 | 2011-09-21 | 同方人工环境有限公司 | Method for controlling stepless adjustment of water-source screw unit |
| CN102616364A (en) * | 2011-01-29 | 2012-08-01 | 珠海格力电器股份有限公司 | Marine seawater source heat pump air-conditioning system |
| CN103206814A (en) * | 2013-04-12 | 2013-07-17 | 南京佳力图空调机电有限公司 | Supercooling device for magnetic suspension refrigerating system with natural cold source |
| WO2016058280A1 (en) * | 2014-10-16 | 2016-04-21 | 中国扬子集团滁州扬子空调器有限公司 | Combined cascade refrigeration air-conditioning system and control method therefor |
| CN106440546A (en) * | 2016-09-05 | 2017-02-22 | 珠海格力电器股份有限公司 | Chilled water way system, adjusting method of system, water chilling unit and air conditioner |
| CN106246550A (en) * | 2016-09-08 | 2016-12-21 | 珠海格力电器股份有限公司 | Control device, control method and the compressor of a kind of guiding valve |
| CN206291546U (en) * | 2016-12-26 | 2017-06-30 | 珠海华隆科技有限公司 | The water-cooling device of temperature control is carried out using magnetic valve bypass waterway |
| CN207196987U (en) * | 2017-08-15 | 2018-04-06 | 珠海格力电器股份有限公司 | Screw-type water chiller |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107560207A (en) | 2018-01-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107560207B (en) | Screw type water chilling unit and control method thereof | |
| CN109282545B (en) | Air-supplying and enthalpy-increasing control method of low-temperature direct-current variable-frequency heat pump system | |
| CN108139107B (en) | Air conditioner and operation method thereof | |
| AU2012266219B2 (en) | A multi-evaporator refrigeration circuit | |
| US8701424B2 (en) | Turbo chiller, heat source system, and method for controlling the same | |
| US10139125B2 (en) | Air-conditioning apparatus | |
| JP2527643B2 (en) | A method of controlling the amount of water change in a water heat source air conditioning system | |
| CN109341122B (en) | Refrigerating system and control method | |
| CN103344064B (en) | Instant waste heat recycling heating unit and water outflow thermostatic control method thereof | |
| CN107906640A (en) | A kind of integrated chilling air conditioning system and its control method for data center | |
| US11624538B2 (en) | Refrigeration device provided with a secondary by-pass branch and method of use thereof | |
| CN103292435A (en) | Air-conditioner control system and control method | |
| CN112325494A (en) | Refrigerant circulation system and control method thereof | |
| JP4287113B2 (en) | Refrigerator control method and refrigeration apparatus | |
| CN106931546B (en) | Heat pump enthalpy-spraying system, control method thereof and air conditioner | |
| CN218781453U (en) | Cooling system and air conditioning unit | |
| US6749016B2 (en) | Brine temperature control apparatus using a three-way proportional valve | |
| CN207196987U (en) | Screw-type water chiller | |
| CN113645809B (en) | Cooling device, air conditioning system, and control method for cooling device | |
| CN115060015A (en) | Cooling system and control method | |
| JPS6256427B2 (en) | ||
| CN103335408B (en) | Used heat utilization system water outlet constant-temperature control method and control device thereof | |
| CN109764568A (en) | Water cooler and control method | |
| CN217979374U (en) | Enhanced vapor injection control system of electronic expansion valve | |
| CN103398503B (en) | Comprehensive waste heat utilization system and outlet-water thermostatic control method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |