CN112146254A - Method for measuring refrigeration performance coefficient of water chilling unit and water chilling unit - Google Patents

Method for measuring refrigeration performance coefficient of water chilling unit and water chilling unit Download PDF

Info

Publication number
CN112146254A
CN112146254A CN202011028013.1A CN202011028013A CN112146254A CN 112146254 A CN112146254 A CN 112146254A CN 202011028013 A CN202011028013 A CN 202011028013A CN 112146254 A CN112146254 A CN 112146254A
Authority
CN
China
Prior art keywords
refrigerant
saturation
temperature
pressure
coefficient
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.)
Pending
Application number
CN202011028013.1A
Other languages
Chinese (zh)
Inventor
宋岩磊
宋禹霏
郝赫
褚玉刚
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xinao Shuneng Technology Co Ltd
Original Assignee
Xinao Shuneng Technology Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Xinao Shuneng Technology Co Ltd filed Critical Xinao Shuneng Technology Co Ltd
Priority to CN202011028013.1A priority Critical patent/CN112146254A/en
Publication of CN112146254A publication Critical patent/CN112146254A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • F24F11/89—Arrangement or mounting of control or safety devices
    • 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
    • F24F11/52—Indication arrangements, e.g. displays
    • 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
    • F25B30/00—Heat pumps
    • F25B30/02—Heat pumps of the compression type
    • 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
    • F25B41/00—Fluid-circulation arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M99/00—Subject matter not provided for in other groups of this subclass

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Thermal Sciences (AREA)
  • Human Computer Interaction (AREA)
  • General Physics & Mathematics (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

The invention relates to the technical field of air conditioners, and provides a method for measuring a refrigeration performance coefficient of a water chilling unit and the water chilling unit, wherein the measuring method comprises the following steps: according to the saturation temperature T of the refrigerating machine evaporator refrigerant of the unitsatSaturation pressure PsatCalculating the saturation air enthalpy value hv and the saturation liquid enthalpy value hl of the refrigerant, then calculating the enthalpy difference delta h of the refrigerant to hv-hl, and according to the collected condensation temperature t of the refrigerantcEvaporation temperature teCalculating compressor refrigerationAnd the agent flow F calculates the cooling capacity Q provided by the refrigerant according to the enthalpy difference delta h-hv-hl of the refrigerant and the flow F of the refrigerant in the compressor, and calculates the coefficient of performance COP of the refrigerator according to the collected refrigerator power W. The initial parameters are acquired by a sensor, and finally the performance coefficient is obtained through function operation, so that the technical problems that the performance coefficient COP calculated in the prior art can only be used for post statistical analysis, the energy efficiency of a unit cannot be monitored and predicted in real time, a cold calorimeter cannot be installed, and the cold system energy coefficient cannot be measured and calculated are solved.

Description

Method for measuring refrigeration performance coefficient of water chilling unit and water chilling unit
Technical Field
The invention relates to the technical field of air conditioners, in particular to a method for measuring a refrigeration performance coefficient of a water chilling unit and the water chilling unit.
Background
With the continuous development of economy, the social demand for green buildings is stronger, and the energy-saving requirement for the water chilling unit is higher and higher. The existing energy efficiency evaluation method for the water chilling unit is generally that a third-party detection mechanism measures a plurality of state points during the operation of the water chilling unit in a pumping mode, and the refrigerating capacity and the power value are obtained through later-stage calculation according to measured data, so that the coefficient of performance (COP) of the water chilling unit is obtained to evaluate the operation energy efficiency of the water chilling unit. The performance coefficient COP obtained by the method can only be used for post statistical analysis, and cannot monitor and predict the energy efficiency of the water chilling unit in real time, so that the energy-saving requirement of the water chilling unit is difficult to realize.
Secondly, the performance coefficient of the existing water chilling unit is measured by measuring chilled water to measure cold quantity Q, then the power consumption W of a compressor motor is measured, and then the performance coefficient COP of the water chilling unit is calculated to be Q/W. According to the measuring method, the cold quantity of the chilled water needs to be measured by using a cold calorimeter, in many projects, the cold calorimeter cannot be installed due to the limitation of pipelines, and the cold system energy coefficient cannot be measured and calculated.
Disclosure of Invention
The invention aims to provide a method for measuring a refrigeration performance coefficient of a water chilling unit and the water chilling unit, and aims to solve the technical problems that in the prior art, the calculated performance coefficient COP can only be used for post statistical analysis, the energy efficiency of the unit cannot be monitored and predicted in real time, a cold calorimeter cannot be installed, and the cold system performance coefficient cannot be measured and calculated.
In order to achieve the purpose, the invention adopts the technical scheme that:
on one hand, the invention provides a method for measuring the refrigeration performance coefficient of a water chilling unit, which is characterized by comprising the following steps:
step S1, according to the refrigerant saturation temperature T of the cold machine evaporator of the unitsatSaturation pressure PsatCalculating a refrigerant saturation air enthalpy value hv and a saturation liquid enthalpy value hl by using a correlation polynomial, wherein the correlation polynomial is as follows:
Figure BDA0002702710850000021
in the formula:
h is the enthalpy value of the refrigerant, a, b, c, d, e, f, g, H, i, j are correlation coefficients, when the saturation air enthalpy value hv and the saturation liquid enthalpy value hl of the refrigerant are calculated, the correlation coefficients are different, and the saturation air enthalpy value hv and the saturation liquid enthalpy value hl of the refrigerant have different enthalpy values according to different refrigerants, wherein the prior art has relevant table specifications and is not repeated;
the saturation temperature is a temperature ts at which the liquid and the vapor are in a dynamic equilibrium state, i.e., a saturated state. In the saturated state, the temperatures of the liquid and vapor are equal. When the saturation temperature is constant, the saturation pressure is also constant; conversely, the saturation temperature is constant when the saturation pressure is constant. The pressure increases and a new dynamic equilibrium state is formed at the new temperature. A certain saturation temperature of the substance must correspond to a certain saturation pressure. The optimum saturation temperature is not a fixed value and varies with ambient conditions.
Saturation pressure means that if a closed container is not filled with liquid, part of the liquid molecules will enter the headspace, called "evaporation". As the number of vapor molecules in the space increases, the vapor pressure generated by the vapor molecules increases, and at a certain time, the number of vapor molecules in the space does not increase any more, and at this time, the number of molecules leaving the liquid and the number of molecules returning from the space reach a dynamic equilibrium, also called a "saturated state". The pressure generated by the vapor at this time is called "saturation pressure". Both saturation temperature and saturation pressure are terms in gas-liquid equilibrium. For the same substance, the saturation pressure is dependent on temperature. The higher the temperature, the more energetic the molecule has, the easier it is to disengage from the liquid and vaporize, and the higher the corresponding saturation pressure. The certain temperature corresponds to a certain saturation pressure, and the two are not independent. Therefore, in the saturated state, the temperature corresponding to the saturation pressure is also called "saturation temperature". The relationship between saturation temperature and saturation pressure for various substances can generally be found in handbooks.
Enthalpy, an important state variable in thermodynamics that characterizes the energy of a matter system, is generally denoted by the symbol H. For a mass of a substance, the enthalpy is defined as H ═ U + pV, where U is the internal energy of the substance, p is the pressure, and V is the volume. The enthalpy per mass of substance is called the specific enthalpy and is expressed as h ═ u + pv. The refrigerant saturation air enthalpy value hv and the saturation liquid enthalpy value hl are enthalpy values of the refrigerant in a saturated gas state or a saturated liquid state respectively.
Step S2, calculating a refrigerant enthalpy difference Δ h ═ hv-hl using the refrigerant saturation air enthalpy value hv and the saturation liquid enthalpy value hl calculated by the formula (1) of the formula step S1, respectively; as can be seen from the above, the enthalpy difference of the refrigerant reflects the difference in enthalpy between saturated gas and saturated liquid states of the refrigerant, i.e., the difference in energy of heat exchange between the refrigerants.
The air conditioner can convert heat, and the refrigerant is the blood of the air conditioner by converting the gaseous state and the liquid state of the refrigerant, and the refrigerant is generally Freon and derivatives thereof.
The substance changes from a liquid state to a gas state to absorb heat, and similarly, the substance changes from a gas state to a liquid state to emit heat. In plateau, water is boiled at a temperature of less than 100 ℃ due to low air pressure, and the pressure of the pressure cooker can be increased, so that the boiling point of the water is increased. The air conditioner utilizes the two principles: the compressor delivers high pressure liquid refrigerant to the evaporator (indoor unit), which expands through the expansion valve and then drops its pressure from liquid to gas to absorb indoor heat. Then the low-pressure gaseous refrigerant is sent back to the compressor to be compressed into high-pressure gaseous refrigerant, and the high-pressure gaseous refrigerant is changed into liquid refrigerant from gaseous refrigerant through the condenser (outdoor unit) to release heat. The high pressure liquid refrigerant is then sent to the evaporator, which constitutes a refrigeration cycle. In this refrigeration cycle, the difference of enthalpy values of the refrigerant in a saturated gas and saturated liquid state, namely the energy difference of refrigeration.
Step S3, according to the collected refrigerant condensation temperature tcEvaporation temperature teAnd calculating the refrigerant flow of the compressor by combining the correlation coefficient, wherein the specific calculation formula is as follows:
Figure BDA0002702710850000031
wherein F is the refrigerant flow of the compressor, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are correlation coefficients, and t is the coefficient of mass flow of the compressoreTo the evaporation temperature, tcIs the condensation temperature;
the condensing temperature refers to the saturation temperature at which the refrigerant vapor in the condenser condenses under a certain pressure. The condensation temperature is not equal to the temperature of the cooling medium, and a heat transfer temperature difference also exists between the condensation temperature and the cooling medium.
The evaporation temperature is the temperature at which the refrigerant boils in the evaporator and corresponds to the corresponding evaporation pressure. The evaporation temperature increases and the evaporation pressure also increases.
The evaporation temperature and the condensation temperature are only surface changes and are directly caused by different changes of the flow rate of the refrigerant of the compressor, so that the evaporation temperature and the condensation temperature have a functional relation with the flow rate of the refrigerant.
It should be noted that, the refrigerant flow rate of the compressor is calculated, and the specific calculation formula is as follows:
Figure BDA0002702710850000041
wherein F is the refrigerant flow rate of the compressor, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are correlation coefficients, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are different according to different correlation coefficients of the refrigerant:
and step S4, calculating the cooling capacity Q provided by the refrigerant as the enthalpy difference delta h-hv-hl and the flow F of the compressor refrigerant, and calculating the coefficient of performance COP of the refrigerator as Q/W according to the collected refrigerator power W.
The air conditioner has an important index, namely the refrigerating capacity, which is the size of the air conditioner, and the air conditioner has the size difference just like the size of a screen of a television, and the only important size index is the refrigerating capacity except the possible size difference of the appearance.
The refrigerating capacity refers to the sum of heat removed from a closed space, a room or an area in unit time when the air conditioner performs refrigerating operation, and the legal measurement unit W (watt) reflects the capacity of the air conditioner capable of bringing refrigerating capacity in unit time. The enthalpy difference delta h-hv-hl of the refrigerant reflects the difference between the saturated vapor enthalpy value hv and the saturated liquid enthalpy value hl during enthalpy heat exchange of the refrigerant, namely the cooling capacity provided by unit flow during heat exchange. Multiplied by the temperature t according to the condensation temperaturecEvaporation temperature teThe calculated compressor refrigerant flow F is the total cooling capacity Q.
The performance coefficient is output heating quantity divided by heating input power, the higher the performance coefficient value is, the stronger the air conditioner heating is, the smaller the power consumption is, and the efficiency of the air conditioner converting electric energy into cold and hot energy is reflected.
In summary, the method for measuring the refrigeration coefficient of performance of the water chilling unit does not adopt the method of measuring the refrigeration capacity Q of chilled water, measuring the power consumption W of the motor of the compressor and calculating the coefficient of performance COP (coefficient of performance) of the unit to be Q/W in the prior art. But according to the refrigerant saturation temperature T acquired by the sensorsatSaturation pressure PsatCalculating the enthalpy value of the refrigerant, calculating the enthalpy difference of the refrigerant according to the enthalpy value of the refrigerant, and then calculating the condensation temperature t of the refrigerant according to the collected condensation temperature t of the refrigerantcEvaporation temperature teAnd finally, calculating the cold quantity Q provided by the refrigerant according to the enthalpy difference of the refrigerant and the flow F of the refrigerant, and further calculating the coefficient of performance COP (coefficient of performance) of the refrigerator to be Q/W. Therefore, the initial parameters are acquired by a sensor and finally obtained by function operation, the real-time refrigeration performance coefficient of the water chilling unit can be calculated, a cold calorimeter is not required to be installed, and the problems that the COP (coefficient of performance) calculation in the prior art can only be used for post statistical analysis and cannot be used for monitoring and predicting the energy efficiency of the unit in real timeAnd the cold calorimeter can not be installed, and the cold system energy coefficient can not be measured and calculated.
In one embodiment, the refrigerant saturation temperature TsatSaturation pressure PsatCondensation temperature tcEvaporation temperature teCollected through a communication interface which receives the saturation temperature T collected by a temperature sensor and a pressure sensor arranged in the refrigerant of the unitsatCondensation temperature tcEvaporation temperature teSaturation pressure Psat。
The communication interface CAN be an RS232 interface, an RS485 interface, a CAN bus interface, a USB interface, a network port and the like, different communication interfaces CAN be adopted according to different conditions, and the simple introduction of the different communication interfaces is as follows:
(1) the RS232 interface, which defines 25 lines, contains two signal channels, a first channel (called the main channel) and a second channel (called the sub channel). Full duplex communication can be achieved using the RS-232 bus, with the primary channel typically being used and the secondary channel being used less often. In general application, full-duplex communication can be realized by using 3 to 9 signal lines, and a simple full-duplex communication process can be realized by using three signal lines (a receiving line, a transmitting line and a signal ground). RS232 has the following disadvantages:
1. the signal level value of the interface is high, reaches dozens of V, easily damages the chip of the interface circuit, is not compatible with TTL level, and therefore a conversion circuit is required to be added when the interface circuit is connected with a single chip circuit.
2. The signal line used by the interface forms a common ground mode communication with other devices, and the common ground mode transmission is easy to generate interference and has weak interference resistance.
3. The transmission distance and speed are limited, and only tens of meters can be communicated at most; only two points can communicate with each other, and multi-machine networking communication cannot be realized.
(2) Aiming at the defects above the RS232 interface, new interface standards such as RS485 appear, and the RS485 has the following characteristics:
1. a logic "1" is represented by a voltage difference between the two wires of + (2-6) V; a logic "0" is represented by a voltage difference between the two wires of- (2-6) V. The interface signal level is lower than RS232, the chip of the circuit is not easy to damage, and the level is compatible with the TTL level and can be conveniently connected with the TTL circuit.
2. The RS485 communication speed is high, and the highest data transmission rate is more than 10 Mbps; the internal physical structure adopts the combination of a balance driver and a check receiver, so that the anti-interference capability is greatly increased.
3. The transmission distance can reach about 1200 meters farthest, but the transmission speed and the transmission distance are in inverse proportion, the maximum communication distance can be reached only at the transmission speed of less than 100KB/s, and relays can be used if the transmission is needed to be carried out for a longer distance.
4. The multi-machine communication can be realized by networking on a bus, a plurality of transceivers are allowed to be hung on the bus, and drivers of different devices such as 32, 64, 128, 256 and the like can be hung on the bus from the conventional RS485 chip.
(3) The CAN bus mainly uses a low-speed fault-tolerant CAN (controller area network), namely ISO11898-3 standard, in the industrial control field, and a high-speed CAN with 500Kbps is commonly used in the automobile field. The CAN system is divided into a high speed CAN system and a low speed CAN system, the high speed CAN system adopts a hard wire as a power type, and the speed is as follows: 500kbps, control ECU, ABS, etc.; low speed CAN is comfort, speed: 125Kbps, mainly controls instruments, prevents burglary and the like. The application examples are as follows:
5 existing 16T/H XXXX gas boilers in a hospital provide 5kg/cm2 steam for facilities such as laundry rooms, preparation rooms, supply rooms, domestic water, central heating and the like, consume 1200 ten thousand m3 of natural gas and 20 ten thousand tons of tap water all the year round. The hospital adopts a relay type mode for heat supply, performs regional management on a heat supply network and is divided into four heat supply areas. The air consumption of winter heating is very large, and accordingly a distributed boiler steam heat supply network intelligent monitoring system based on a CAN field bus is designed. The field application shows that: the building automation system has the characteristics of strong anti-interference capability, easy field configuration, high networking degree, friendly human-computer interface and the like.
The USB interface and the internet interface are common communication interfaces, and the principle thereof will not be described herein.
The method for measuring the refrigeration performance coefficient of the water chilling unit mainly adopts the pressure sensor and the temperature sensor to acquire the pressure and temperature parameters of the water chilling unit in real time, and adopts different communication interfaces to transmit acquired data to the controller according to different interfaces of the sensors. If the number of the data acquisition contacts is large, the data acquisition contacts are switched and acquired through intermediate equipment, such as a data acquisition card, a concentrator and a router, and finally transmitted to a controller for processing, so that the enthalpy difference and the flow rate of the refrigerant are respectively calculated, and further, the cold quantity Q (delta h) F provided by the refrigerant and the coefficient of performance COP (coefficient of performance) Q/W of the refrigerator are calculated.
In one embodiment, the chiller evaporator refrigerant saturation temperature T of the unitsatCan also be based on the pressure P before the expansion valveTEVAnd calculating the pressure drop delta P of the expansion valve, specifically: calculating the pressure P behind the expansion valvein＝PTEVΔ P, using the post-expansion-valve pressure PinCalculating the saturation temperature T after throttling according to the correlation polynomial of the saturation temperature and the saturation pressuresatThe saturation temperature and saturation pressure associated polynomial is:
Tsat＝l×Pin 5+m×Pin 4+n×Pin 3+x×Pin 2+y×Pin+z (3)
wherein a, b, c, d, e and f are correlation coefficients.
The situation is that the saturated temperature and the saturated pressure of the liquid supply of the evaporator can not be directly acquired through a communication interface, and the pressure P before the expansion valve is acquired through a pressure sensor or a pressure transmitterTEVPressure drop delta P of the expansion valve, and acquired data are transmitted to the controller to calculate the pressure P behind the expansion valvein＝PTEVΔ P, then using the post-expansion-valve pressure PinCalculating the saturation temperature T after throttling according to the correlation polynomial of the saturation temperature and the saturation pressuresat. In the above-mentioned saturation temperature and saturation pressure correlation polynomial, a, b, c, d, e, f are correlation coefficients, which are different according to the refrigerant, for example, the correlation coefficient corresponding to the R134a refrigerant is:
a:1.62844593187421E-03；b:-5.59153132388297E-02；c:0.772232450488314；d:-5.65890258298171；e:27.7768684197473；f:-48.3942211592152。
the correlation coefficient is generated based on refrigerant physical property data issued by the national institute of thermal and technical research (national standards and technology), and the following criteria for selecting the correlation coefficient are the same.
In one embodiment, the cold machine power W is acquired by scanning a one-dimensional code or a two-dimensional code of the cold water machine set, or is manually input. The cold machine power W of the cold water machine set corresponds to the model of the machine set, and the cold machine power W can be extracted through the controller or the value of the cold machine power W can be input manually by scanning relevant information of the machine set.
On the other hand, the invention also provides a water chilling unit, which comprises a controller, a communication interface and a heat pump system, wherein the controller is connected with the heat pump system through the communication interface, the heat pump system comprises an evaporator, a condenser, an expansion valve and a compressor, and the controller can execute the method for measuring the refrigeration performance coefficient of the water chilling unit. Wherein, the controller is a micro CPU such as a singlechip and an ARM processor.
In one embodiment, the system further comprises a temperature sensor and a pressure sensor, wherein the temperature sensor is used for acquiring the saturation temperature T of the refrigerantsatCondensation temperature tcEvaporation temperature te(ii) a The pressure sensor collects the saturation pressure P of the refrigerantsatAnd the expansion valve front pressure PTEVAnd an expansion valve pressure drop Δ P.
In one embodiment, the device further comprises a display device for displaying the calculation result and/or the detection data; further comprises a storage unit for storing the calculation result and/or the detection data
In one embodiment, the display device comprises a touch screen.
In one embodiment, the controller is any one of a single chip microcomputer, an ARM processor and a PLC.
In one embodiment, the communication interface includes, but is not limited to, an RS232 interface, an RS485 interface, a CAN bus interface, a USB interface, and a network interface.
The pressure sensor and the temperature sensor are arranged at the specific positions of the evaporator, the condenser and the expansion valve without specific limitation, the sensors are generally in contact connection with the evaporator, the condenser and the expansion valve, parameters such as pressure, temperature and the like of a refrigerant are collected and then transmitted to a controller (a micro CPU such as a single chip microcomputer and an ARM processor) through a data line, and the controller can finally calculate the performance coefficient only according to a preset algorithm corresponding to the method for measuring the refrigeration performance coefficient of the water chilling unit. The display device is used for displaying the detection data such as temperature, pressure and the like collected in real time and the calculation results such as flow, cold quantity, performance coefficients and the like, and the storage unit is a memory and is used for storing the calculation results and the detection data.
The method for measuring the refrigeration performance coefficient of the water chilling unit and the water chilling unit have the advantages that at least:
the invention is not a method for measuring the refrigerating capacity Q of the chilled water, measuring the power consumption W of the motor of the compressor and calculating the coefficient of performance COP (coefficient of performance) of the unit to be Q/W in the prior art. But according to the refrigerant saturation temperature T acquired by the sensorsatSaturation pressure PsatCalculating the enthalpy value of the refrigerant, calculating the enthalpy difference of the refrigerant according to the enthalpy value of the refrigerant, and then calculating the condensation temperature t of the refrigerant according to the collected condensation temperature t of the refrigerantcEvaporation temperature teAnd finally, calculating the cold quantity Q provided by the refrigerant according to the enthalpy difference of the refrigerant and the flow F of the refrigerant, and further calculating the coefficient of performance COP (coefficient of performance) of the refrigerator to be Q/W. Therefore, the initial parameters are acquired by a sensor and finally obtained by function operation, the real-time refrigeration performance coefficient of the water chilling unit can be calculated, and a cold calorimeter is not required to be installed, so that the technical problems that in the prior art, the calculated performance coefficient COP can only be used for post statistical analysis, the energy efficiency of the unit cannot be monitored and predicted in real time, the cold calorimeter cannot be installed, and the cold system performance coefficient cannot be measured and calculated are solved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed for the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a flowchart of a method for measuring a refrigeration coefficient of performance of a chiller according to an embodiment of the present invention;
fig. 2 is a schematic block diagram of a water chiller according to an embodiment of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly or indirectly secured to the other element. When an element is referred to as being "connected to" another element, it can be directly or indirectly connected to the other element. The terms "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positions based on the orientations or positions shown in the drawings, and are for convenience of description only and not to be construed as limiting the technical solution. The terms "first", "second" and "first" are used merely for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features. The meaning of "plurality" is two or more unless specifically limited otherwise.
Example 1
Referring to fig. 1, the present embodiment provides a method for measuring a refrigeration performance coefficient of a chiller, including the following steps:
step S1, according to the refrigerant saturation temperature T of the cold machine evaporator of the unitsatSaturation pressure PsatCalculating the saturation air enthalpy value hv and the saturation liquid enthalpy value hl of the refrigerant by using a correlation polynomial, wherein the correlation polynomial is as follows:
Figure BDA0002702710850000091
in the formula:
h is the enthalpy value of the refrigerant, a, b, c, d, e, f, g, H, i and j are correlation coefficients, and when the saturated vapor enthalpy value hv and the saturated liquid enthalpy value hl of the refrigerant are calculated, the correlation coefficients are different.
For the R134a refrigerant, the correlation coefficients of the saturation enthalpy value hv are respectively as follows: a-485.891397077446, b-0.389212302176763, c-420.719120740499, d-8.01935341014245E-03, E-474.224392702626, f-3.25180713876596, g-6.12622104323146E-05, h-27.2341664707717, i-8.60534926735803, and j-8.62204705819907E-02.
The correlation coefficients of the saturated liquid enthalpy value hl are respectively as follows: 141.916629008589, b 1.97122562246359, c 170.886378855162, d 3.43817355550419E-03, E4.26587410336271, f 4.22078524872035, g 3.07434565857469E-05, h 5.4935587960138, i 0.281513719073855, and j 3.61346932218521E-02.
The correlation coefficient is generated based on refrigerant property data issued by the National Institute of thermal Properties of the National Institute of Technology (National Standards and Technology), and the following criteria for selecting the correlation coefficient are the same.
The saturation temperature is a temperature ts at which the liquid and the vapor are in a dynamic equilibrium state, i.e., a saturated state. In the saturated state, the temperatures of the liquid and vapor are equal. When the saturation temperature is constant, the saturation pressure is also constant; conversely, the saturation temperature is constant when the saturation pressure is constant. The pressure increases and a new dynamic equilibrium state is formed at the new temperature. A certain saturation temperature of the substance must correspond to a certain saturation pressure. The optimum saturation temperature is not a fixed value and varies with ambient conditions.
Saturation pressure means that if a closed container is not filled with liquid, part of the liquid molecules will enter the headspace, called "evaporation". As the number of vapor molecules in the space increases, the vapor pressure generated by the vapor molecules increases, and at a certain time, the number of vapor molecules in the space does not increase any more, and at this time, the number of molecules leaving the liquid and the number of molecules returning from the space reach a dynamic equilibrium, also called a "saturated state". The pressure generated by the vapor at this time is called "saturation pressure". Both saturation temperature and saturation pressure are terms in gas-liquid equilibrium. For the same substance, the saturation pressure is dependent on temperature. The higher the temperature, the more energetic the molecule has, the easier it is to disengage from the liquid and vaporize, and the higher the corresponding saturation pressure. The certain temperature corresponds to a certain saturation pressure, and the two are not independent. Therefore, in the saturated state, the temperature corresponding to the saturation pressure is also called "saturation temperature". The relationship between saturation temperature and saturation pressure for various substances can generally be found in handbooks.
Enthalpy, an important state variable in thermodynamics that characterizes the energy of a matter system, is generally denoted by the symbol H. For a mass of a substance, the enthalpy is defined as H ═ U + pV, where U is the internal energy of the substance, p is the pressure, and V is the volume. The enthalpy per mass of substance is called the specific enthalpy and is expressed as h ═ u + pv. The refrigerant saturation air enthalpy value hv and the saturation liquid enthalpy value hl are enthalpy values of the refrigerant in a saturated gas state or a saturated liquid state respectively.
Step S2, calculating a refrigerant enthalpy difference Δ h ═ hv-hl using the refrigerant saturation air enthalpy value hv and the saturation liquid enthalpy value hl calculated by the formula (1) of the formula step S1, respectively; as can be seen from the above, the enthalpy difference of the refrigerant reflects the difference in enthalpy between saturated gas and saturated liquid states of the refrigerant, i.e., the difference in energy of heat exchange between the refrigerants.
The air conditioner can convert heat, and the refrigerant is the blood of the air conditioner by converting the gaseous state and the liquid state of the refrigerant, and the refrigerant is generally Freon and derivatives thereof.
The substance changes from a liquid state to a gas state to absorb heat, and similarly, the substance changes from a gas state to a liquid state to emit heat. In plateau, water is boiled at a temperature of less than 100 ℃ due to low air pressure, and the pressure of the pressure cooker can be increased, so that the boiling point of the water is increased. The air conditioner utilizes the two principles: the compressor delivers high pressure liquid refrigerant to the evaporator (indoor unit), which expands through the expansion valve and then drops its pressure from liquid to gas to absorb indoor heat. Then the low-pressure gaseous refrigerant is sent back to the compressor to be compressed into high-pressure gaseous refrigerant, and the high-pressure gaseous refrigerant is changed into liquid refrigerant from gaseous refrigerant through the condenser (outdoor unit) to release heat. The high pressure liquid refrigerant is then sent to the evaporator, which constitutes a refrigeration cycle. In this refrigeration cycle, the difference of enthalpy values of the refrigerant in a saturated gas and saturated liquid state, namely the energy difference of refrigeration.
Step S3, according to the collected refrigerant condensation temperature tcEvaporation temperature teAnd calculating the refrigerant flow of the compressor by combining the correlation coefficient, wherein the specific calculation formula is as follows:
Figure BDA0002702710850000111
wherein F is the refrigerant flow of the compressor, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are correlation coefficients, and t is the coefficient of mass flow of the compressoreTo the evaporation temperature, tcIs the condensation temperature;
the condensing temperature refers to the saturation temperature at which the refrigerant vapor in the condenser condenses under a certain pressure. The condensation temperature is not equal to the temperature of the cooling medium, and a heat transfer temperature difference also exists between the condensation temperature and the cooling medium.
The evaporation temperature is the temperature at which the refrigerant boils in the evaporator and corresponds to the corresponding evaporation pressure. The evaporation temperature increases and the evaporation pressure also increases.
The evaporation temperature and the condensation temperature are only surface changes and are directly caused by different changes of the flow rate of the refrigerant of the compressor, so that the evaporation temperature and the condensation temperature have a functional relation with the flow rate of the refrigerant.
It should be noted that, the refrigerant flow rate of the compressor is calculated, and the specific calculation formula is as follows:
Figure BDA0002702710850000121
in the formula, F is the refrigerant flow of the compressor, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are correlation coefficients, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are different according to different correlation coefficients of the refrigerant, and if the correlation coefficient of a certain type of compressor is: c1 ═ 9878.3, C2 ═ 356.2737, C3 ═ 41.6874, C4 ═ 5.60881, C5 ═ 0.72688, C6 ═ 1.33187, C7 ═ 0.056274, C8 ═ 0.21394, C9 ═ 0.007295, C10 ═ 0.018549:
and step S4, calculating the cooling capacity Q provided by the refrigerant according to the enthalpy difference delta h-hv-hl of the refrigerant and the flow F of the refrigerant in the compressor, and calculating the coefficient of performance COP of the refrigerator according to the collected power W of the refrigerator. The cold machine power W is acquired by scanning a one-dimensional code and a two-dimensional code of the cold water machine set, or is manually input. The cold machine power W of the cold water machine set corresponds to the model of the machine set, and the cold machine power W can be extracted through the controller or the value of the cold machine power W can be input manually by scanning relevant information of the machine set.
The air conditioner has an important index, namely the refrigerating capacity, which is the size of the air conditioner, and the air conditioner has the size difference just like the size of a screen of a television, and the only important size index is the refrigerating capacity except the possible size difference of the appearance.
The refrigerating capacity refers to the sum of heat removed from a closed space, a room or an area in unit time when the air conditioner performs refrigerating operation, and the legal measurement unit W (watt) reflects the capacity of the air conditioner capable of bringing refrigerating capacity in unit time. The enthalpy difference delta h-hv-hl of the refrigerant reflects the difference between the saturated vapor enthalpy value hv and the saturated liquid enthalpy value hl during enthalpy heat exchange of the refrigerant, namely the cooling capacity provided by unit flow during heat exchange. Multiplied by the temperature t according to the condensation temperaturecEvaporation temperature teThe calculated compressor refrigerant flow F is the total cooling capacity Q.
The performance coefficient is output heating quantity divided by heating input power, the higher the performance coefficient value is, the stronger the air conditioner heating is, the smaller the power consumption is, and the efficiency of the air conditioner converting electric energy into cold and hot energy is reflected.
The working principle of the method for measuring the refrigeration performance coefficient of the water chilling unit provided by the embodiment is as follows:
in the method for measuring the refrigeration coefficient of performance of the water chilling unit in the embodiment, a method for measuring the refrigeration capacity Q of chilled water, measuring the power consumption W of a compressor motor and calculating the coefficient of performance COP Q/W in the prior art is not adopted. But according to the refrigerant saturation temperature T acquired by the sensorsatSaturation pressure PsatCalculating the enthalpy value of the refrigerant, calculating the enthalpy difference of the refrigerant according to the enthalpy value of the refrigerant, and then calculating the condensation temperature t of the refrigerant according to the collected condensation temperature t of the refrigerantcEvaporation temperature teAnd finally, calculating the cold quantity Q provided by the refrigerant according to the enthalpy difference of the refrigerant and the flow F of the refrigerant, and further calculating the coefficient of performance COP (coefficient of performance) of the refrigerator to be Q/W. Therefore, the initial parameters are acquired by a sensor and finally obtained by function operation, the real-time refrigeration performance coefficient of the water chilling unit can be calculated, and a cold calorimeter is not required to be installed, so that the technical problems that in the prior art, the calculated performance coefficient COP can only be used for post statistical analysis, the energy efficiency of the unit cannot be monitored and predicted in real time, the cold calorimeter cannot be installed, and the cold system performance coefficient cannot be measured and calculated are solved.
In the present embodiment, the refrigerant saturation temperature TsatSaturation pressure PsatCondensation temperature tcEvaporation temperature teCollected through a communication interface, the communication interface receives the saturation temperature T collected by a temperature sensor and a pressure sensor arranged in the refrigerant of the unitsatCondensation temperature tcEvaporation temperature teSaturation pressure Psat. The communication interface CAN be an RS232 interface, an RS485 interface, a CAN bus interface, a USB interface, a network port and the like, different communication interfaces CAN be adopted according to different conditions, and the simple introduction of the different communication interfaces is as follows:
(1) the RS232 interface, which defines 25 lines, contains two signal channels, a first channel (called the main channel) and a second channel (called the sub channel). Full duplex communication can be achieved using the RS-232 bus, with the primary channel typically being used and the secondary channel being used less often. In general application, full-duplex communication can be realized by using 3 to 9 signal lines, and a simple full-duplex communication process can be realized by using three signal lines (a receiving line, a transmitting line and a signal ground). RS232 has the following disadvantages:
1. the signal level value of the interface is high, reaches dozens of V, easily damages the chip of the interface circuit, is not compatible with TTL level, and therefore a conversion circuit is required to be added when the interface circuit is connected with a single chip circuit.
2. The signal line used by the interface forms a common ground mode communication with other devices, and the common ground mode transmission is easy to generate interference and has weak interference resistance.
3. The transmission distance and speed are limited, and only tens of meters can be communicated at most; only two points can communicate with each other, and multi-machine networking communication cannot be realized.
(2) Aiming at the defects above the RS232 interface, new interface standards such as RS485 appear, and the RS485 has the following characteristics:
1. a logic "1" is represented by a voltage difference between the two wires of + (2-6) V; a logic "0" is represented by a voltage difference between the two wires of- (2-6) V. The interface signal level is lower than RS232, the chip of the circuit is not easy to damage, and the level is compatible with the TTL level and can be conveniently connected with the TTL circuit.
2. The RS485 communication speed is high, and the highest data transmission rate is more than 10 Mbps; the internal physical structure adopts the combination of a balance driver and a check receiver, so that the anti-interference capability is greatly increased.
3. The transmission distance can reach about 1200 meters farthest, but the transmission speed and the transmission distance are in inverse proportion, the maximum communication distance can be reached only at the transmission speed of less than 100KB/s, and relays can be used if the transmission is needed to be carried out for a longer distance.
4. The multi-machine communication can be realized by networking on a bus, a plurality of transceivers are allowed to be hung on the bus, and drivers of different devices such as 32, 64, 128, 256 and the like can be hung on the bus from the conventional RS485 chip.
(3) The CAN bus mainly uses a low-speed fault-tolerant CAN (controller area network), namely ISO11898-3 standard, in the industrial control field, and a high-speed CAN with 500Kbps is commonly used in the automobile field. The CAN system is divided into a high speed CAN system and a low speed CAN system, the high speed CAN system adopts a hard wire as a power type, and the speed is as follows: 500kbps, control ECU, ABS, etc.; low speed CAN is comfort, speed: 125Kbps, mainly controls instruments, prevents burglary and the like. The application examples are as follows:
5 existing 16T/H XXXX gas boilers in a hospital provide 5kg/cm2 steam for facilities such as laundry rooms, preparation rooms, supply rooms, domestic water, central heating and the like, consume 1200 ten thousand m3 of natural gas and 20 ten thousand tons of tap water all the year round. The hospital adopts a relay type mode for heat supply, performs regional management on a heat supply network and is divided into four heat supply areas. The air consumption of winter heating is very large, and accordingly a distributed boiler steam heat supply network intelligent monitoring system based on a CAN field bus is designed. The field application shows that: the building automation system has the characteristics of strong anti-interference capability, easy field configuration, high networking degree, friendly human-computer interface and the like.
The USB interface and the internet interface are common communication interfaces, and the principle thereof will not be described herein.
The method for measuring the refrigeration performance coefficient of the water chilling unit mainly adopts the pressure sensor, the temperature sensor and the communication interface to acquire the pressure and temperature parameters of the water chilling unit in real time, and adopts different communication interfaces to transmit acquired data to the controller according to different interfaces of the sensor. If the number of the data acquisition contacts is large, the data acquisition contacts are switched and acquired through intermediate equipment, such as a data acquisition card, a concentrator and a router, and finally transmitted to a controller for processing, so that the enthalpy difference and the flow rate of the refrigerant are respectively calculated, and further, the cold quantity Q (delta h) F provided by the refrigerant and the coefficient of performance COP (coefficient of performance) Q/W of the refrigerator are calculated.
Example 2
Referring to fig. 1, the present embodiment provides a method for measuring a refrigeration performance coefficient of a chiller, including the following steps:
step S1, according to the refrigerant saturation temperature T of the cold machine evaporator of the unitsatSaturation pressure PsatCalculating the saturation air enthalpy value hv and the saturation liquid enthalpy value hl of the refrigerant by using a correlation polynomial, wherein the correlation polynomial is as follows:
Figure BDA0002702710850000151
in the formula:
h is the enthalpy value of the refrigerant, a, b, c, d, e, f, g, H, i, j are correlation coefficients, when the saturated air enthalpy value hv and the saturated liquid enthalpy value hl of the refrigerant are calculated, the correlation coefficients are different, a group of correlation coefficient parameters is given in embodiment 1, and details are not repeated;
step S2, calculating a refrigerant enthalpy difference Δ h ═ hv-hl using the refrigerant saturation air enthalpy value hv and the saturation liquid enthalpy value hl calculated by the formula (1) of the formula step S1, respectively; as can be seen from the above, the enthalpy difference of the refrigerant reflects the difference in enthalpy between saturated gas and saturated liquid states of the refrigerant, i.e., the difference in energy of heat exchange between the refrigerants.
Step S3, according to the collected refrigerant condensation temperature tcEvaporation temperature teAnd calculating the refrigerant flow of the compressor by combining the correlation coefficient, wherein the specific calculation formula is as follows:
Figure BDA0002702710850000152
wherein F is the refrigerant flow of the compressor, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are correlation coefficients, and t is the coefficient of mass flow of the compressoreTo the evaporation temperature, tcIs the condensation temperature;
it should be noted that, the refrigerant flow rate of the compressor is calculated, and the specific calculation formula is as follows:
Figure BDA0002702710850000161
wherein F is the refrigerant flow rate of the compressor, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are correlation coefficients, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are different according to different correlation coefficients of the refrigerant, a set of correlation coefficient parameters is provided in embodiment 1, and details are not repeated here:
and step S4, calculating the cooling capacity Q provided by the refrigerant according to the enthalpy difference delta h-hv-hl of the refrigerant and the flow F of the refrigerant in the compressor, and calculating the coefficient of performance COP of the refrigerator according to the collected power W of the refrigerator. The cold machine power W is acquired by scanning a one-dimensional code and a two-dimensional code of the cold water machine set, or is manually input. The cold machine power W of the cold water machine set corresponds to the model of the machine set, and the cold machine power W can be extracted through the controller or the value of the cold machine power W can be input manually by scanning relevant information of the machine set.
In this embodiment, the saturation temperature T of the refrigerant in the evaporator of the chiller of the unitsatAccording to the pressure P before the expansion valveTEVThe pressure drop delta P of the expansion valve is calculated (the pressure before the expansion valve is measured by a pressure sensor arranged in front of the expansion valve, and the pressure drop of the expansion valve is measured by a differential pressure sensor in front of and behind the expansion valve), specifically: calculating the pressure P behind the expansion valvein＝PTEVΔ P, using the post-expansion-valve pressure PinCalculating the saturation temperature T after throttling according to the correlation polynomial of the saturation temperature and the saturation pressuresatThe saturation temperature and saturation pressure associated polynomial is:
Tsat＝l×Pin 5+m×Pin 4+n×Pin 3+x×Pin 2+y×Pin+z (3)
wherein a, b, c, d, e and f are correlation coefficients.
The present embodiment is adapted to enable the saturation pressure P to be obtained in advancesatThe water chilling unit can not directly acquire the liquid supply saturation temperature of the evaporator through the communication interface, and the pressure P before the expansion valve is acquired through the pressure sensor or the pressure transmitterTEVPressure drop delta P of the expansion valve, and acquired data are transmitted to the controller to calculate the pressure P behind the expansion valvein＝PTEVΔ P, then using the post-expansion-valve pressure PinCalculating the saturation temperature T after throttling according to the correlation polynomial of the saturation temperature and the saturation pressuresat. In the above-mentioned saturation temperature and saturation pressure correlation polynomial, a, b, c, d, e, f are correlation coefficients, which are different according to the refrigerant, for example, the correlation coefficient corresponding to the R134a refrigerant is:
a:1.62844593187421E-03；b:-5.59153132388297E-02；c:0.772232450488314；d:-5.65890258298171；e:27.7768684197473；f:-48.3942211592152。
in addition, the condensation temperature t of the refrigerantcEvaporation temperature teCollected by a temperature sensor.
The working principle of the method for measuring the refrigeration performance coefficient of the water chilling unit provided by the embodiment is as follows:
in the method for measuring the refrigeration coefficient of performance of the water chilling unit in the embodiment, a method for measuring the refrigeration capacity Q of chilled water, measuring the power consumption W of a compressor motor and calculating the coefficient of performance COP Q/W in the prior art is not adopted. But according to the refrigerant saturation temperature T acquired by the sensorsatSaturation pressure PsatCalculating the enthalpy value of the refrigerant, calculating the enthalpy difference of the refrigerant according to the enthalpy value of the refrigerant, and then calculating the condensation temperature t of the refrigerant according to the collected condensation temperature t of the refrigerantcEvaporation temperature teAnd finally, calculating the cold quantity Q provided by the refrigerant according to the enthalpy difference of the refrigerant and the flow F of the refrigerant, and further calculating the coefficient of performance COP (coefficient of performance) of the refrigerator to be Q/W. Therefore, the initial parameters are acquired by a sensor and finally obtained by function operation, the real-time refrigeration performance coefficient of the water chilling unit can be calculated, and a cold calorimeter is not required to be installed, so that the technical problems that in the prior art, the calculated performance coefficient COP can only be used for post statistical analysis, the energy efficiency of the unit cannot be monitored and predicted in real time, the cold calorimeter cannot be installed, and the cold system performance coefficient cannot be measured and calculated are solved.
Meanwhile, the method is used for acquiring the pressure P before the expansion valve through a pressure sensor or a pressure transmitter aiming at the condition that the liquid supply saturation temperature and saturation pressure of the evaporator cannot be directly acquired through a communication interfaceTEVPressure drop delta P of the expansion valve, and acquired data are transmitted to the controller to calculate the pressure P behind the expansion valvein＝PTEVΔ P, then using the post-expansion-valve pressure PinFinally calculating the saturation temperature T after throttling according to the correlation polynomial of the saturation temperature and the saturation pressuresatThe method of (1).
Example 3
As shown in fig. 2, the present invention further provides a water chilling unit, which includes a controller, a communication interface, and a heat pump system, wherein the controller is connected to the heat pump system through the communication interface, the heat pump system includes an evaporator, a condenser, an expansion valve, and a compressor, and the controller can execute the method for measuring the refrigeration coefficient of performance of the water chilling unit. The controller is any one of micro CPUs such as a singlechip, an ARM processor, a PLC and the like. The communication interface is RS232 interface, RS485 interface, CAN bus interface, USB interface, network interface, etc.
Wherein, the device also comprises a temperature sensor and a pressure sensor, wherein the temperature sensor is used for collecting the saturation temperature T of the refrigerantsatCondensation temperature tcEvaporation temperature te(ii) a The pressure sensor collects the saturation pressure P of the refrigerantsatAnd the expansion valve front pressure PTEVAnd an expansion valve pressure drop Δ P.
The device also comprises a display device used for displaying the calculation result and/or the detection data; further comprises a storage unit for storing the calculation result and/or the detection data
Wherein the display device comprises a touch screen.
The working principle of the water chilling unit provided by the embodiment is as follows:
the pressure sensor and the temperature sensor are arranged at specific positions on the evaporator, the condenser and the expansion valve without specific limitation, the sensors are generally in contact connection with the evaporator, the condenser and the expansion valve, parameters such as pressure, temperature and the like of a refrigerant are collected and then transmitted to a controller (a micro CPU such as a single chip microcomputer, an ARM processor, a PLC and the like) through a data line, and the controller can finally calculate the performance coefficient only according to a preset algorithm corresponding to the method for measuring the refrigeration performance coefficient of the water chilling unit. The display device is used for displaying the detection data such as temperature, pressure and the like collected in real time and the calculation results such as flow, cold quantity, performance coefficients and the like, and the storage unit is a memory and is used for storing the calculation results and the detection data.
The water chilling unit that this embodiment provided lies in at least:
the initial parameters of the water chilling unit provided by the embodiment are acquired in real time through the pressure sensor (or the pressure transmitter) and the temperature sensor (or the temperature transmitter), and are finally calculated through the built-in algorithm program of the controller, so that the real-time refrigeration performance coefficient of the water chilling unit can be calculated, and a cold calorimeter does not need to be installed. In addition, the display device can display calculation results and detection data, is good in visualization and convenient to monitor.
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 (10)

1. A method for measuring the refrigeration performance coefficient of a water chilling unit is characterized by comprising the following steps:
step S1, according to the refrigerant saturation temperature T of the cold machine evaporator of the unitsatSaturation pressure PsatCalculating a refrigerant saturation air enthalpy value hv and a saturation liquid enthalpy value hl by using a correlation polynomial, wherein the correlation polynomial is as follows:
Figure FDA0002702710840000011
in the formula:
h is the enthalpy value of the refrigerant, a, b, c, d, e, f, g, H, i and j are correlation coefficients, and when the saturated air enthalpy value hv and the saturated liquid enthalpy value hl of the refrigerant are calculated, the correlation coefficients are different;
step S2, calculating a refrigerant enthalpy difference Δ h ═ hv-hl using the refrigerant saturation air enthalpy value hv and the saturation liquid enthalpy value hl calculated by the formula (1) of the formula step S1, respectively;
step S3, according to the collected refrigerant condensation temperature tcEvaporation temperature teAnd calculating the refrigerant flow of the compressor by combining the correlation coefficient, wherein the specific calculation formula is as follows:
Figure FDA0002702710840000012
wherein F is the refrigerant flow of the compressor, C1, C2, C3, C4, C5, C6, C7, C8, C9 and C10 are correlation coefficients, and t is the coefficient of mass flow of the compressoreTo the evaporation temperature, tcIs the condensation temperature;
and step S4, calculating the cooling capacity Q provided by the refrigerant as the enthalpy difference delta h-hv-hl and the flow F of the compressor refrigerant, and calculating the coefficient of performance COP of the refrigerator as Q/W according to the collected refrigerator power W.
2. The chiller refrigeration performance coefficient measuring method of claim 1, wherein said refrigerant saturation temperature TsatSaturation pressure PsatCondensation temperature tcEvaporation temperature teCollected through a communication interface which receives the saturation temperature T collected by a temperature sensor and a pressure sensor arranged in the refrigerant of the unitsatCondensation temperature tcEvaporation temperature teSaturation pressure Psat。
3. The method of claim 1 wherein the chiller evaporator refrigerant saturation temperature T of the chiller is measuredsatAccording to the pressure P before the expansion valveTEVAnd calculating the pressure drop delta P of the expansion valve to obtain: calculating the pressure P behind the expansion valvein＝PTEVΔ P, using the post-expansion-valve pressure PinCalculating the saturation temperature T after throttling according to the correlation polynomial of the saturation temperature and the saturation pressuresatThe saturation temperature and saturation pressure associated polynomial is:
Tsat＝l×Pin 5+m×Pin 4+n×Pin 3+x×Pin 2+y×Pin+z (3)
wherein l, m, n, x, y and z are correlation coefficients.
4. The method for measuring the refrigeration coefficient of performance of a chiller according to claim 1, wherein the chiller power W is collected by scanning a one-dimensional code, a two-dimensional code or manually inputted.
5. A chiller, comprising a controller, a communication interface, and a heat pump system, wherein the controller is connected to the heat pump system through the communication interface, wherein the heat pump system comprises an evaporator, a condenser, an expansion valve, and a compressor, and wherein the controller is capable of executing the chiller refrigeration performance coefficient measuring method according to any one of claims 1 to 3.
6. The chiller according to claim 5 further comprising a temperature sensor for sensing refrigerant saturation temperature T, a pressure sensorsatCondensation temperature tcEvaporation temperature te(ii) a The pressure sensor collects the saturation pressure P of the refrigerantsatAnd the expansion valve front pressure PTEVAnd an expansion valve pressure drop Δ P.
7. The chiller according to claim 5 or 6 further comprising display means for displaying the calculation and/or the sensed data; the device also comprises a storage unit used for storing the calculation result and/or the detection data.
8. The chiller according to claim 7 wherein said display device comprises a touch screen.
9. The chiller according to claim 5 wherein the controller is any one of a single chip, an ARM processor, and a PLC.
10. The chiller according to claim 5 wherein said communication interface includes but is not limited to an RS232 interface, an RS485 interface, a CAN bus interface, a USB interface, a network port.
CN202011028013.1A 2020-09-26 2020-09-26 Method for measuring refrigeration performance coefficient of water chilling unit and water chilling unit Pending CN112146254A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202011028013.1A CN112146254A (en) 2020-09-26 2020-09-26 Method for measuring refrigeration performance coefficient of water chilling unit and water chilling unit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202011028013.1A CN112146254A (en) 2020-09-26 2020-09-26 Method for measuring refrigeration performance coefficient of water chilling unit and water chilling unit

Publications (1)

Publication Number Publication Date
CN112146254A true CN112146254A (en) 2020-12-29

Family

ID=73897484

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202011028013.1A Pending CN112146254A (en) 2020-09-26 2020-09-26 Method for measuring refrigeration performance coefficient of water chilling unit and water chilling unit

Country Status (1)

Country Link
CN (1) CN112146254A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113758017A (en) * 2021-09-03 2021-12-07 广东纽恩泰新能源科技发展有限公司 Initial opening degree calculation method, device, equipment and medium for electronic expansion valve
CN113760003A (en) * 2021-09-07 2021-12-07 苏州海宇新辰医疗科技有限公司 Temperature control method, device and storage medium
CN114383875A (en) * 2021-12-16 2022-04-22 深圳市前海能源科技发展有限公司 Dual-working-condition water chilling unit performance testing method and system and storage medium
CN114992788A (en) * 2021-03-02 2022-09-02 广东美的暖通设备有限公司 Temperature calculation method and device before and after throttling, electronic equipment and storage medium

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080245083A1 (en) * 2006-08-15 2008-10-09 American Power Conversion Corporation Method and apparatus for cooling
JP2011149568A (en) * 2010-01-19 2011-08-04 Panasonic Corp Heat pump device
CN103154639A (en) * 2010-10-12 2013-06-12 三菱电机株式会社 Air-conditioning apparatus
CN106839340A (en) * 2017-03-16 2017-06-13 广东美的制冷设备有限公司 A kind of air conditioner refrigerating measuring method, device and air-conditioner
CN109654652A (en) * 2018-11-17 2019-04-19 华中科技大学 A kind of air conditioner cooling/heating amount prediction technique based on data mining technology

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080245083A1 (en) * 2006-08-15 2008-10-09 American Power Conversion Corporation Method and apparatus for cooling
JP2011149568A (en) * 2010-01-19 2011-08-04 Panasonic Corp Heat pump device
CN103154639A (en) * 2010-10-12 2013-06-12 三菱电机株式会社 Air-conditioning apparatus
CN106839340A (en) * 2017-03-16 2017-06-13 广东美的制冷设备有限公司 A kind of air conditioner refrigerating measuring method, device and air-conditioner
CN109654652A (en) * 2018-11-17 2019-04-19 华中科技大学 A kind of air conditioner cooling/heating amount prediction technique based on data mining technology

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
刘晖 肖红: "对水蒸气饱和温度发算公式的考察", 《内蒙古石油化工》 *
刘晖: "制冷剂饱和温度的反算公式", 《流体机械》 *
王运朋: "《实用汽车空调技术》", 27 February 1995, 广东科技出版社 *
骆如碧: "氦焓值与压力和温度的函数关系", 《低温与特气》 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114992788A (en) * 2021-03-02 2022-09-02 广东美的暖通设备有限公司 Temperature calculation method and device before and after throttling, electronic equipment and storage medium
CN113758017A (en) * 2021-09-03 2021-12-07 广东纽恩泰新能源科技发展有限公司 Initial opening degree calculation method, device, equipment and medium for electronic expansion valve
CN113760003A (en) * 2021-09-07 2021-12-07 苏州海宇新辰医疗科技有限公司 Temperature control method, device and storage medium
CN113760003B (en) * 2021-09-07 2022-03-29 苏州海宇新辰医疗科技有限公司 Temperature control method, device and storage medium
CN114383875A (en) * 2021-12-16 2022-04-22 深圳市前海能源科技发展有限公司 Dual-working-condition water chilling unit performance testing method and system and storage medium
CN114383875B (en) * 2021-12-16 2024-02-09 深圳市前海能源科技发展有限公司 Dual-working-condition water chiller performance test method, system and storage medium

Similar Documents

Publication Publication Date Title
CN112146254A (en) Method for measuring refrigeration performance coefficient of water chilling unit and water chilling unit
CN104807113B (en) A kind of air conditioner outdoor machine defrosting decision method
CN112050299B (en) Air conditioner
CN102353403B (en) Methods for measuring chilled water flow and cooling medium flow of central air-conditioning host machine
CN105066273A (en) Heat exchanger suitable for capacitor and reactor chamber
CN107388514A (en) Air conditioner and its efficiency computational methods
CN102269661B (en) Testing system for performance of air-cooled compression condensing unit
CN109000949A (en) Water cooler appraisal procedure and power-economizing method based on water cooler thermodynamical model
CN113175735B (en) Method for calculating capacity energy efficiency of air conditioner, computer storage medium and air conditioner
CN102520010B (en) Condenser dirt detection method for vapor compression cycle cold water unit
CN113175738A (en) Method for calculating capacity energy efficiency of air conditioner, computer storage medium and air conditioner
CN202649190U (en) Refrigerating fluid cycle performance testing device
Padilla Exergy analysis of the performance of a variable refrigerant flow (VRF) air conditioning system
CN204943994U (en) The kind of refrigeration cycle oil content of refrigeration plant and the measurement mechanism of efficiency
CN103776651B (en) Teat pump boiler streamline test macro and method
CN109764490A (en) Air conditioner coolant supply state detection method, device and air-conditioning and storage medium
CN105135541A (en) Heat exchange method suitable for capacitor and electric reactor chambers
CN205119578U (en) A detecting system for detecting heat transfer ability of regenerator
CN209415822U (en) A kind of on-line checking density steam double-effect type suction-type lithium bromide low-temperature cold water unit
CN209415823U (en) A kind of on-line checking density flue gas type suction-type lithium bromide low-temperature cold water unit
CN210320722U (en) Refrigeration heat pump device of R410a refrigerant
TW201307774A (en) System and method for monitoring refrigeration device
Fernando et al. Performance of a single-family heat pump at different working conditions using small quantity of propane as refrigerant
CN105299969B (en) A kind of detecting system for being used to detect the exchange capability of heat of regenerator
CN209230970U (en) Share the weather simulation laboratory of cold source

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
RJ01 Rejection of invention patent application after publication
RJ01 Rejection of invention patent application after publication

Application publication date: 20201229