CN110857826A - Dynamic superheat degree control method for air source cold and hot water unit - Google Patents
Dynamic superheat degree control method for air source cold and hot water unit Download PDFInfo
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- CN110857826A CN110857826A CN201810957476.2A CN201810957476A CN110857826A CN 110857826 A CN110857826 A CN 110857826A CN 201810957476 A CN201810957476 A CN 201810957476A CN 110857826 A CN110857826 A CN 110857826A
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- superheat degree
- target value
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
Abstract
The patent refers to the field of 'control of combustion engines'. The invention relates to the field of a superheat degree control method of an air source cold and hot water unit. The main technical problem who solves is: the air source cold and hot water unit has the problems of reduced unit operation efficiency, difficult oil return, even compressor burnout and the like due to the phenomena of unstable control of an electronic expansion valve, liquid compression of a compressor, overhigh exhaust temperature and the like under the working conditions of low refrigeration water temperature or heating in winter. The main methods for solving the problems are as follows: according to the mechanism that the exhaust superheat degree dynamically changes along with the suction superheat degree, the electronic expansion valve selects the exhaust superheat degree as a main control variable and the suction superheat degree as a secondary control variable in the control process, so that the dynamic control of the superheat degree is realized, the superheat degree control precision of an air source cold and hot water unit is effectively improved, the oil return effect of the unit is improved, and the unit efficiency is improved.
Description
Technical Field
The invention relates to the field of superheat degree control methods of air source cold and hot water units, in particular to a dynamic superheat degree control method of an air source cold and hot water unit.
Background
The air source cold and hot water unit works in a reverse clamping cycle, the throttling element is one of key elements in the cycle, and the cold and hot load adjustment and the adjustment accuracy of the air source cold and hot water unit are closely related to the opening adjustment and the adjustment accuracy of the throttling element. At present, an electronic expansion valve is mainly adopted for throttling in an air source cold and hot water unit which is currently applied to heating and refrigerating in the north, the traditional electronic expansion valve control is single air suction superheat degree control or electronic expansion valve opening degree control according to environmental temperature, namely, the air suction superheat degree of a compressor is monitored to be compared with a set target value, and if the monitored superheat degree is deviated from the set target value, the opening degree of the electronic expansion valve is adjusted through a proportional-integral-derivative (PID) adjusting algorithm and a control mechanism. When the refrigerating and heating working condition is low in water temperature or in winter, the suction superheat degree of the unit generally changes between 0 and 2 ℃, the change range is very small, and if the control method is controlled by the single suction superheat degree, the phenomena of unstable control of an expansion valve, liquid compression of a compressor, overhigh discharge temperature of the compressor and the like often occur, so that the problems of reduction of the operation efficiency of the unit, difficulty in oil return of the unit, even burnout of the compressor and the like are caused.
Therefore, the air source cold and hot water unit can not only use one fixed temperature point for controlling the superheat degree of the unit in a wide operation range, and the superheat degree of the unit can be changed according to specific operation conditions, and other parameters are introduced for combined control, so that the unit is always in the best operation state.
Disclosure of Invention
The invention aims to overcome the technical defects, and provides a dynamic superheat control method of an air source cold and hot water unit aiming at the problems of reduced unit operation efficiency, difficult unit oil return, even burning of a compressor and the like caused by the adoption of a single air suction superheat control method of the existing air source cold and hot water unit.
A dynamic superheat degree control method for an air source cold and hot water unit is characterized in that parameters, variables and algorithms related in an electronic expansion valve adjusting process comprise: the control system comprises an air suction superheat degree, an exhaust superheat degree, an air suction superheat degree target value, an exhaust superheat degree target value changing algorithm, a proportional integral derivative algorithm, a main control variable exhaust superheat degree and a secondary control variable air suction superheat degree. The target value of the suction superheat degree is based on the suction superheat degree when the heat exchange efficiency of the evaporator is optimal, the target value of the exhaust superheat degree is based on the exhaust superheat degree which ensures the safe operation of the compressor, and the suction superheat degree when the heat exchange efficiency of the evaporator is optimal and the optimal exhaust superheat degree when the compressor is safe to operate are determined through experiments. And the adjustment algorithms of the variable exhaust superheat target value algorithm and the proportional integral derivative algorithm are determined according to experiments.
A dynamic superheat degree control method of an air source cold and hot water unit is characterized in that: and simultaneously monitoring the suction superheat degree (SSH) and the exhaust superheat Degree (DSH), wherein the exhaust superheat degree is used as a main control variable and the suction superheat degree is used as a secondary control variable in the control process, target values of the main exhaust superheat degree variable and the secondary suction superheat degree variable are dynamically adjusted according to the deviation of the target values from target set values, when the suction superheat degree of the air source cold and hot water unit is lower than a control set target value, the set target value of the exhaust superheat degree is properly adjusted to be higher until the suction superheat degree also reaches a set target value interval, otherwise, when the suction superheat degree of the air source cold and hot water unit is higher than the set target value, the exhaust superheat degree control target value is properly adjusted to be lower until the suction superheat degree also reaches the set target value interval.
The invention has the beneficial effects that: through the dynamic superheat degree control method of the air source cold and hot water unit, the air source cold and hot water unit is more stable and reliable under various operation working conditions, particularly low ambient temperature heating operation working conditions in winter, the exhaust superheat degree and the suction superheat degree of the unit can be stably controlled within a target range, and compared with a conventional single superheat degree control method, the energy efficiency ratio of the air source cold and hot water unit is improved by more than 10% under the same ambient temperature parameters.
Drawings
FIG. 1 is a schematic diagram of the principle of the dynamic superheat degree control method of the air source cold and hot water unit.
In the figure, SSH is the degree of superheat of suction gas, DSH is the degree of superheat of discharge gas, and PID is proportional integral derivative.
Detailed Description
An embodiment of the present invention will be described with reference to fig. 1.
As shown in fig. 1, a dynamic superheat degree control method for an air source cold and hot water unit, parameters, variables and algorithms involved in an electronic expansion valve adjusting process comprise: the control system comprises an air suction superheat degree, an exhaust superheat degree, an air suction superheat degree target value, an exhaust superheat degree target value changing algorithm, a proportional integral derivative algorithm, a main control variable exhaust superheat degree and a secondary control variable air suction superheat degree. The target value of the suction superheat degree is based on the suction superheat degree when the heat exchange efficiency of the evaporator is optimal, the target value of the exhaust superheat degree is based on the exhaust superheat degree which ensures the safe operation of the compressor, and the suction superheat degree when the heat exchange efficiency of the evaporator is optimal and the optimal exhaust superheat degree when the compressor is safe to operate are determined through experiments. And the adjusting algorithms of the variable exhaust superheat target value algorithm and the proportional integral derivative algorithm are determined according to experiments.
As shown in fig. 1, a method for controlling the dynamic superheat degree of an air source water chiller-heater unit has the following control principle or method: and simultaneously monitoring the air suction superheat degree and the exhaust superheat degree of a compressor of the air source cold and hot water unit, wherein the exhaust superheat degree is used as a main control variable in the control process, and the air suction superheat degree is used as a secondary control variable. The target values of the exhaust superheat degree main control variable and the suction superheat degree secondary control variable are dynamically adjusted according to the deviation of the target values from a target set value, when the suction superheat degree of an air source cold and hot water unit is 1-2 degrees lower than a control set target value, the set target value of the exhaust superheat degree is properly adjusted to be high, the specific quantity of the increased regulation is determined according to experiments, after the exhaust superheat degree is increased, the opening degree of the electronic expansion valve is reduced, the flow of refrigerant in a circulation loop of the air source cold and hot water unit is reduced, the suction superheat degree is gradually reduced, when the exhaust superheat degree is adjusted to the target value and the suction superheat degree does not reach a set target value interval, the set target value of the exhaust superheat degree is properly adjusted to be high again, the specific quantity of the increased regulation is determined according to experiments, and the adjustment of the exhaust superheat degree is stopped until the suction superheat degree reaches the set target, thereby enabling the air source chiller-heater unit to operate in an optimal state.
On the contrary, when the suction superheat degree of the air source cold and hot water unit is higher than the control range, the exhaust superheat degree control target value is properly adjusted to be lower, so that the opening degree of the electronic expansion valve is properly opened, the refrigerant flow in a circulation loop of the air source cold and hot water unit is increased, the suction superheat degree is gradually reduced, when the suction superheat degree is not within a set target value range when the exhaust superheat degree is adjusted to the target value, the set target value of the exhaust superheat degree is properly adjusted to be lower again, the specific amount of the adjustment is determined according to experiments, and the adjustment is stopped until the suction superheat degree is within the set target value range, so that the air source cold and hot water unit operates in the optimal state.
The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.
Claims (4)
1. A control principle of a dynamic superheat degree control method of an air source cold and hot water unit is as follows: and simultaneously monitoring the suction superheat degree (SSH) and the exhaust superheat Degree (DSH), wherein the exhaust superheat degree is used as a main control variable and the suction superheat degree is used as a secondary control variable in the control process, target values of the main exhaust superheat degree variable and the secondary suction superheat degree variable are dynamically adjusted according to the deviation of the target values from target set values, when the suction superheat degree of the air source cold and hot water unit is lower than a control set target value, the set target value of the exhaust superheat degree is properly adjusted to be higher until the suction superheat degree also reaches a set target value interval, otherwise, when the suction superheat degree of the air source cold and hot water unit is higher than the set target value, the exhaust superheat degree control target value is properly adjusted to be lower until the suction superheat degree also reaches the set target value interval.
2. The dynamic superheat control method for the air source chiller/heater unit as claimed in claim 1, wherein the parameters, variables and algorithms involved in the adjustment process of the electronic expansion valve include: the control system comprises an air suction superheat degree, an exhaust superheat degree, an air suction superheat degree target value, an exhaust superheat degree target value changing algorithm, a proportional integral derivative algorithm, a main control variable exhaust superheat degree and a secondary control variable air suction superheat degree.
3. The dynamic superheat degree control method of the air source cold and hot water unit according to claim 1, characterized in that: the target value of the suction superheat degree is based on the suction superheat degree when the heat exchange efficiency of the evaporator is optimal, the target value of the exhaust superheat degree is based on the exhaust superheat degree which ensures the safe operation of the compressor, and the suction superheat degree when the heat exchange efficiency of the evaporator is optimal and the optimal exhaust superheat degree when the compressor is safe to operate are determined through experiments.
4. And the adjustment algorithms of the variable exhaust superheat target value algorithm and the proportional integral derivative algorithm are determined according to experiments.
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| CN201810957476.2A CN110857826A (en) | 2018-08-22 | 2018-08-22 | Dynamic superheat degree control method for air source cold and hot water unit |
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| CN201810957476.2A CN110857826A (en) | 2018-08-22 | 2018-08-22 | Dynamic superheat degree control method for air source cold and hot water unit |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111623569A (en) * | 2020-06-02 | 2020-09-04 | 江苏拓米洛环境试验设备有限公司 | Temperature control device and method of temperature control equipment |
| CN111780370A (en) * | 2020-07-03 | 2020-10-16 | 海信（山东）空调有限公司 | Air conditioner and control method of electronic expansion valve |
| CN113587499A (en) * | 2020-04-14 | 2021-11-02 | 青岛海尔空调器有限总公司 | Refrigerating machine oil circulation amount control method of air conditioning system |
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| CN104634033A (en) * | 2015-01-28 | 2015-05-20 | 中国科学院青岛生物能源与过程研究所 | Electronic expansion valve control system and method |
| CN105157292A (en) * | 2015-07-06 | 2015-12-16 | 重庆美的通用制冷设备有限公司 | Control method and device for electronic expansion valves of air cooling screw unit |
| EP3190357A1 (en) * | 2016-01-08 | 2017-07-12 | Fujitsu General Limited | Air conditioner |
| CN107621102A (en) * | 2017-09-14 | 2018-01-23 | 南京天加环境科技有限公司 | A kind of method based on double degrees of superheat control electric expansion valve |
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2018
- 2018-08-22 CN CN201810957476.2A patent/CN110857826A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104634033A (en) * | 2015-01-28 | 2015-05-20 | 中国科学院青岛生物能源与过程研究所 | Electronic expansion valve control system and method |
| CN105157292A (en) * | 2015-07-06 | 2015-12-16 | 重庆美的通用制冷设备有限公司 | Control method and device for electronic expansion valves of air cooling screw unit |
| EP3190357A1 (en) * | 2016-01-08 | 2017-07-12 | Fujitsu General Limited | Air conditioner |
| CN107621102A (en) * | 2017-09-14 | 2018-01-23 | 南京天加环境科技有限公司 | A kind of method based on double degrees of superheat control electric expansion valve |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113587499A (en) * | 2020-04-14 | 2021-11-02 | 青岛海尔空调器有限总公司 | Refrigerating machine oil circulation amount control method of air conditioning system |
| CN113587499B (en) * | 2020-04-14 | 2022-10-28 | 青岛海尔空调器有限总公司 | Refrigerating machine oil circulation amount control method of air conditioning system |
| CN111623569A (en) * | 2020-06-02 | 2020-09-04 | 江苏拓米洛环境试验设备有限公司 | Temperature control device and method of temperature control equipment |
| CN111780370A (en) * | 2020-07-03 | 2020-10-16 | 海信（山东）空调有限公司 | Air conditioner and control method of electronic expansion valve |
| CN111780370B (en) * | 2020-07-03 | 2021-08-03 | 海信（山东）空调有限公司 | Air conditioner and control method of electronic expansion valve |
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Application publication date: 20200303 |