CN111623570A - Water chilling unit energy efficiency diagnosis method and system - Google Patents
Water chilling unit energy efficiency diagnosis method and system Download PDFInfo
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- CN111623570A CN111623570A CN202010516345.8A CN202010516345A CN111623570A CN 111623570 A CN111623570 A CN 111623570A CN 202010516345 A CN202010516345 A CN 202010516345A CN 111623570 A CN111623570 A CN 111623570A
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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
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Abstract
The invention discloses a method and a system for diagnosing the energy efficiency of a water chilling unit. Under the determined operation condition, the invention analyzes and diagnoses the thermodynamic process of each link of the cooling tower, the condenser, the evaporator, the compressor and the throttling by comparing the actual COP of the water chilling unit with the theoretical value thereof, can accurately find out the problem, greatly improves the scientificity of the energy efficiency diagnosis of the water chilling unit, can improve the energy efficiency of the water chilling unit without replacing the whole water chilling unit under partial conditions, and saves the energy-saving reconstruction cost.
Description
Technical Field
The invention relates to the technical field of heating and ventilation engineering, in particular to a method and a system for diagnosing energy efficiency of a water chilling unit.
Background
With the development of the national economic level, the energy consumption of buildings is continuously increased. The government department emphasizes economic development and strengthens the attention on energy conservation continuously, reduces the energy consumption of buildings in a feasible range and is an important direction for energy conservation. About one fourth of the building energy consumption is consumed by the refrigeration system. Therefore, the method has important significance for the energy efficiency diagnosis of the refrigerating unit.
The energy efficiency diagnosis problem of the water chilling unit is actually a problem of scientifically evaluating the allowable performance of the water chilling unit. Once scientific evaluation is carried out, various factors influencing the performance of the water chilling unit are analyzed and clarified, and a scientific energy efficiency diagnosis suggestion can be provided naturally. Currently, the performance index of energy efficiency ratio (COP) is generally adopted to evaluate the actual performance of the water chilling unit. The COP is the ratio of the refrigerating capacity to the power consumption, and the higher the value of the COP is, the better the economical efficiency of the running of the water chilling unit is, the more energy is saved, and the worse the COP is, the more energy is consumed.
The method commonly used at present is to fit the COP into a function of the load factor, namely, the COP of the water chilling unit is only related to the load factor and is not related to the operating conditions of the water chilling unit, such as the temperature of cold water, the temperature of cooling water and the like. In fact, the levels of the cold water temperature and the cooling water temperature directly determine the levels of the evaporation temperature and the condensation temperature, and the levels of the two temperatures influence the refrigeration efficiency. Meanwhile, although the COP can intuitively reflect the overall operation performance of the water chilling unit, the COP kills the specific influence of different factors, and cannot accurately describe the performance of the water chilling unit. Therefore, when the existing building is subjected to energy-saving transformation, the energy-saving transformation of the refrigerating system is usually to directly replace the whole refrigerating system when the energy efficiency is low or a water chilling unit is damaged, so that great resource waste is caused.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
The invention is provided in view of the above and/or unreasonable energy efficiency diagnosis of the existing energy-saving modified chiller unit.
Therefore, one technical problem to be solved by the present invention is to provide a method for diagnosing energy efficiency of a chiller, which can perform comprehensive diagnosis on each component and a cooling tower of the chiller, accurately find out the problem, select an optimal maintenance or replacement scheme, improve the energy efficiency ratio of the chiller, reduce the cost, and solve the problem of resource waste caused by directly replacing the whole refrigeration system in the energy-saving reconstruction of the existing refrigeration system.
In order to solve the technical problems, the invention provides the following technical scheme: a water chilling unit energy efficiency diagnosis method comprises the following steps of obtaining rated parameters, obtaining unit refrigerating capacity and input power according to a water chilling unit model, and obtaining evaporator temperature, supercooling degree, superheat degree, chilled water inlet temperature, outlet water temperature, cooling water inlet temperature and outlet water temperature under rated working conditions according to a use scene; calculating rated parameters, and calculating the energy efficiency ratio of the water chilling unit, the efficiency of a compressor, the heat transfer capacity of a condenser, the logarithmic mean temperature difference of the condenser, the product of the heat transfer coefficient of the condenser and the heat transfer area, the heat transfer capacity of an evaporator, the logarithmic mean difference of the evaporator, the product of the heat transfer coefficient of the evaporator and the heat transfer area, and the temperature difference between the outlet water of a cooling tower and an outdoor wet bulb under the rated working condition according to the obtained rated parameters; measuring actual operation data, including operation data of a cooling tower, a compressor, a condenser, an evaporator and a thermal expansion valve in the components of the water chiller; calculating actual operation parameters, calculating the heat transfer capacity of the condenser, the logarithmic average temperature difference measured by the condenser, the product of the heat transfer coefficient and the heat transfer area of the condenser, the heat transfer capacity of the evaporator, the logarithmic average difference of the evaporator, the product of the heat transfer coefficient and the heat transfer area of the evaporator under actual operation according to the measured actual operation data, and further calculating the energy efficiency ratio of the water chilling unit, the input power of the compressor and the measured efficiency of the compressor; and (3) energy efficiency diagnosis of the water chilling unit, respectively diagnosing the cooling tower, the compressor, the condenser, the evaporator and the thermal expansion valve, estimating annual power consumption and annual operation cost, calculating the investment recovery year limit, determining an energy efficiency ratio efficiency threshold value, and diagnosing the water chilling unit system.
As a preferable scheme of the energy efficiency diagnosis method for the water chilling unit, the method comprises the following steps: the measurement of the specific operation data of the cooling tower, the compressor, the condenser, the evaporator and the thermostatic expansion valve comprises the steps of measuring the temperature of cooling water entering the cooling tower, the temperature of the cooling water flowing out of the cooling tower and the temperature of outdoor air wet bulb; measuring the suction pressure of the compressor, the exhaust pressure of the compressor and the input power of the water chilling unit; measuring the temperature of cooling water entering the condenser, the temperature of cooling water exiting the condenser, and the flow of cooling water through the condenser; measuring the temperature of the chilled water entering the evaporator, the temperature of the chilled water exiting the evaporator and the flow rate of the chilled water; the temperature of a return air pipe between the evaporator and the compressor is measured.
As a preferable scheme of the energy efficiency diagnosis method for the water chilling unit, the method comprises the following steps: the calculation formula of the investment recovery age is
Wherein Y is the investment recovery time limit for replacing the water chilling unit, P is the initial investment of the water chilling unit,
determining the energy efficiency ratio efficiency threshold value:
wherein, ηCOPFor energy efficiency ratio efficiency, the ratio of the measured value of the COP of the water chilling unit to the theoretical value of the COP of the water chilling unit under the measuring environment is defined, namely
k is the ratio of the initial investment to the annual theoretical operating cost.
As a preferable scheme of the energy efficiency diagnosis method for the water chilling unit, the method comprises the following steps: the diagnostic standard of the cooling tower, the compressor, the condenser, the evaporator, the thermostatic expansion valve and the water chilling unit system is as follows:
if the cooling tower is changedThermal efficiency ηCooling towerIf less than 95%, overhauling and maintaining the cooling tower;
if the evaporator heat transfer efficiency ηQ evaporatorEfficiency η of < 85% or the product of evaporator heat transfer coefficient and heat transfer area(KF) evaporatorIf less than 85%, the evaporator is overhauled or replaced;
if the condenser heat transfer efficiency ηQ condenserEfficiency η of < 85% or the product of condenser heat transfer coefficient and heat transfer area(KF) condenserIf less than 85%, the evaporator is overhauled or replaced;
if the compressor efficiency is poor delta ηCompressor with a compressor housing having a plurality of compressor bladesMore than 20%, and repairing or replacing the compressor;
if the superheat degree is equal to the temperature of the air return pipe-evaporation temperature, and if the superheat degree of the thermostatic expansion valve is not between 5 and 8 ℃, proper adjustment is needed;
if ηCOP＜ηCOPAnd (5) replacing the water chilling unit according to the threshold value.
As a preferable scheme of the energy efficiency diagnosis method for the water chilling unit, the method comprises the following steps: the calculation formula of the heat exchange efficiency of the cooling tower is
Wherein tw1, tw2 and ts are the temperature of cooling water entering and leaving the cooling tower and the temperature of outdoor air wet bulb respectively, and the calculation formula of the heat transfer efficiency of the evaporator is
The product of the heat transfer coefficient and the heat transfer area of the evaporator has an efficiency calculation formula
The heat transfer efficiency of the condenser is calculated by the formula
The efficiency calculation formula of the product of the heat transfer coefficient and the heat transfer area of the condenser is
The compressor efficiency difference is expressed by a formula of delta ηCompressor with a compressor housing having a plurality of compressor blades＝ηTheory of compressor-ηCOP，ηTheory of compressorIs the theoretical efficiency of the compressor.
The invention provides a water chilling unit energy efficiency diagnosis system, which is used for solving the problems of more parameters, complex calculation and easy confusion and error in the diagnosis method.
In order to solve the technical problems, the invention provides the following technical scheme: a water chilling unit energy efficiency diagnosis system comprises a first calculation module, a second calculation module and a control module, wherein the first calculation module is used for calculating a water chilling unit energy efficiency ratio, compressor efficiency, condenser heat transfer capacity, a condenser logarithmic mean temperature difference, a product of a condenser heat transfer coefficient and a heat transfer area, evaporator heat transfer capacity, an evaporator logarithmic mean difference, a product of an evaporator heat transfer coefficient and a heat transfer area, and a cooling tower outlet water and outdoor wet bulb temperature difference; the second calculation module is logically connected with the first calculation module and is used for calculating annual power consumption, annual operating cost, investment recovery age, an energy efficiency ratio efficiency threshold, cooling tower heat exchange efficiency, evaporator heat transfer efficiency, the product efficiency of the evaporator heat transfer coefficient and the heat transfer area, condenser heat transfer efficiency, the product efficiency of the condenser heat transfer coefficient and the heat transfer area, compressor efficiency difference and superheat degree; the measuring module is logically connected with the first calculating module and used for measuring specific operation data of the cooling tower, the compressor, the condenser, the evaporator and the thermal expansion valve; and the diagnosis module is connected with the first calculation module and the second calculation module and is used for diagnosing the cooling tower, the compressor, the condenser, the evaporator, the thermostatic expansion valve and the water chilling unit system.
As a preferable scheme of the energy efficiency diagnosis system for the water chilling unit of the present invention, the following steps are performed: the measurement module transmits the measured data to the first calculation module, the first calculation module respectively calculates parameter values under rated working conditions and measured values under actual operation, and the first calculation module and the second calculation module transmit the calculated results to the diagnosis module for diagnosis to obtain diagnosis results.
As a preferable scheme of the energy efficiency diagnosis system for the water chilling unit of the present invention, the following steps are performed: the measuring module comprises a thermometer, a pressure gauge, a power meter and a flowmeter.
The invention has the beneficial effects that: under the determined operation condition, the invention analyzes and diagnoses the thermodynamic process of each link of the cooling tower, the condenser, the evaporator, the compressor and the throttling by comparing the actual COP of the water chilling unit with the theoretical value thereof, can accurately find out the problem, greatly improves the scientificity of the energy efficiency diagnosis of the water chilling unit, can improve the energy efficiency of the water chilling unit without replacing the whole water chilling unit under partial conditions, and saves the energy-saving reconstruction cost.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced 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 based on these drawings without inventive exercise. Wherein:
FIG. 1 is a flow chart of a method for diagnosing energy efficiency of a chiller according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a refrigeration cycle of a chiller according to an embodiment of the present invention;
FIG. 3 is a pressure-enthalpy diagram of the refrigeration cycle corresponding to FIG. 2;
FIG. 4 is a graph of chiller input power versus load rate for an embodiment of the present invention;
FIG. 5 is a graph illustrating determination of an age threshold for return on investment in one embodiment provided by the present invention;
fig. 6 is a logic connection diagram of a water chiller unit energy efficiency diagnosis system according to an embodiment of the invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
The present invention will be described in detail with reference to the drawings, wherein the cross-sectional views illustrating the structure of the device are not enlarged partially in general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
Meanwhile, in the description of the present invention, it should be noted that the terms "upper, lower, inner and outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operate, and thus, cannot be construed as limiting the present invention. Furthermore, the terms first, second, or third are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted, connected and connected" in the present invention are to be understood broadly, unless otherwise explicitly specified or limited, for example: can be fixedly connected, detachably connected or integrally connected; they may be mechanically, electrically, or directly connected, or indirectly connected through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1
Referring to fig. 1 to 5, the present embodiment provides a method for diagnosing energy efficiency of a chiller, which comprehensively diagnoses a cooling tower, a compressor, a condenser, an evaporator, a thermostatic expansion valve, etc. of the chiller, and is convenient for comprehensive analysis and accurate problem finding. Comprises the following steps of (a) carrying out,
s1, acquiring rated parameters, acquiring unit refrigerating capacity and input power according to the type of the water chilling unit, and acquiring evaporator temperature, supercooling degree, superheat degree, chilled water inlet temperature, outlet water temperature, cooling water inlet temperature and outlet water temperature under rated working conditions according to a use scene; s2, calculating rated parameters, and calculating the energy efficiency ratio of the water chilling unit, the efficiency of the compressor, the heat transfer capacity of the condenser, the logarithmic mean temperature difference of the condenser, the product of the heat transfer coefficient of the condenser and the heat transfer area, the heat transfer capacity of the evaporator, the logarithmic mean difference of the evaporator, the product of the heat transfer coefficient of the evaporator and the heat transfer area, and the temperature difference between the outlet water of the cooling tower and the outdoor wet bulb according to the obtained rated parameters under rated working conditions; s3, measuring actual operation data, including operation data of a cooling tower, a compressor, a condenser, an evaporator and a thermostatic expansion valve in the water cooling unit component; s4, calculating actual operation parameters, calculating the heat transfer quantity of a condenser, the measured logarithmic mean temperature difference of the condenser, the product of the heat transfer coefficient of the condenser and the heat transfer area, the heat transfer quantity of an evaporator, the logarithmic mean difference of the evaporator, the product of the heat transfer coefficient of the evaporator and the heat transfer area under actual operation according to the measured actual operation data, and further calculating the energy efficiency ratio of a water chilling unit, the input power of a compressor and the measured efficiency of the compressor; s5 diagnosing the energy efficiency of the water chilling unit, respectively diagnosing the cooling tower, the compressor, the condenser, the evaporator and the thermal expansion valve, estimating annual power consumption and annual running cost, calculating the investment recovery year limit, determining the energy efficiency ratio efficiency threshold value and diagnosing the water chilling unit system.
It should be noted that the refrigeration unit system mainly includes four major components of a compressor, a condenser, an expansion valve and an evaporator, and the four major components correspond to four thermodynamic processes of compression, heat release, throttling and heat absorption of a vapor compression refrigeration cycle. The compressor is a power provider in the refrigeration system; the expansion valve is used as a throttling device to change the refrigerant from a high-pressure state to a low-pressure state, the evaporator and the condenser are two heat exchange devices of the refrigeration system and are responsible for heat exchange of the whole system, and the running condition of the evaporator directly influences the performance of the system. The four major components jointly form an organic whole of the refrigeration system, the operation conditions are mutually related, the problem of any one component can affect the operation of other components, the condition and the performance of the system, and the normal and efficient operation of the whole system can be ensured only if the components are matched with each other and are in a normal working state.
Referring to fig. 2, the vapor compression refrigeration mainly comprises a compressor, a condenser, a thermal expansion valve and an evaporator, and four major components. The change process of the refrigerant in the refrigeration system is as follows: the refrigerant in a dry saturated state is sucked into the compressor from the evaporator, is changed into superheated gaseous refrigerant through the adiabatic compression process, then enters the condenser through compression and discharge, is cooled and condensed at the constant temperature and the constant pressure in the condenser to release heat to become saturated liquid refrigerant, then is subjected to pressure reduction and temperature reduction through the adiabatic throttling process of the expansion valve to become refrigerant in a wet steam state, and then enters the evaporator to absorb heat and be gasified into dry saturated steam under the constant temperature and the constant pressure state, so that a cycle is formed. Referring to fig. 3, the most convenient to perform a vapor compression refrigeration cycle thermodynamic calculation is lgp-h (pressure-enthalpy diagram).
In the implementation, a water chilling unit manufacturer provides the refrigerating capacity and the input power of the unit to obtain the rated COP of the water chilling unitRated valueRefrigeration capacity/input power. The general parameters of the rated working condition of the water chilling unit are as follows: the evaporator temperature is 4 ℃, the supercooling degree is 3 ℃, the superheat degree is 5 ℃, the chilled water inlet temperature is 12 ℃, the outlet water temperature is 7 ℃, the cooling water inlet temperature is 32 ℃, and the outlet water temperature is 37 ℃. Performing related thermodynamic calculation by a vapor compression refrigeration cycle dead pressure enthalpy diagram:
refrigerating capacity kJ/kg of unit mass refrigerant: q ═ h1-h5
Energy consumed kJ/kg: w ═ h2-h1
Refrigerant mass flow kg/s:
input power KW of the compressor: mW is P ═ mW
Theoretical COP of the unit:
total compressor efficiency of η COPRated value/COPTheory of nominal
The flow of cooling water in the condenser can be obtained from parameters provided by the manufacturer, then:
heat transfer capacity of the condenser: qCondenser＝mCooling watercCooling water(tw2-tw1)，
Wherein, tw1、tw2The temperature of cooling water entering and exiting the condenser and the constant pressure specific heat capacity c of the cooling waterCooling waterCorresponding to a temperature of
Logarithmic mean temperature difference of condenser:
product of condenser heat transfer coefficient and heat transfer area:
the flow of the chilled water in the evaporator can be obtained from parameters provided by a manufacturer, then:
heat transfer capacity of evaporator: qEvaporator with a heat exchanger＝mChilled watercChilled water(td1-td2)，
Wherein, td1、td2The temperature of the chilled water entering and exiting the evaporator and the constant pressure specific heat capacity c of the chilled waterChilled waterCorresponding to a temperature of
Logarithmic mean temperature difference of evaporator:
product of condenser heat transfer coefficient and heat transfer area:
the heat exchange efficiency of the cooling tower is as follows:
wherein, tw1、tw2、tsThe temperature of cooling water entering and leaving the cooling tower and the temperature of outdoor air wet bulb are respectively.
Temperature difference between outlet water of the cooling tower and outdoor wet bulb:
taking η out of the water chilling unit under the rated working conditionCooling tower95%, the temperature of the cooling water was reduced to 32 ℃ at 37 ℃. The difference between the outlet water of the cooling tower and the outdoor wet bulb temperature is 0.26 ℃ according to the formula.
Further, the measurement of specific operational data of the cooling tower, the compressor, the condenser, the evaporator and the thermostatic expansion valve comprises: measuring the temperature of cooling water entering the cooling tower, the temperature of the cooling water flowing out of the cooling tower and the temperature of an outdoor air wet bulb; measuring the suction pressure of a compressor, the exhaust pressure of the compressor and the input power of a water chilling unit; measuring the temperature of cooling water entering the condenser, the temperature of the cooling water flowing out of the condenser and the flow of the cooling water passing through the condenser; measuring the temperature of the chilled water entering the evaporator, the temperature of the chilled water exiting the evaporator and the flow rate of the chilled water; the temperature of the return air pipe between the evaporator and the compressor is measured and used for calibrating the thermostatic expansion valve.
In this embodiment, the method and formula for calculating the measured value of the relevant parameter refer to the following:
Qcondenser measurement＝mCooling water measurementcCooling water(tMeasurement of cooling water outflow-tMeasurement of cooling water inflow)
Condensation temperature:the discharge pressure of the compressor is used as the saturation pressure in the condenser, and the approximate condensing temperature t is obtained by looking up a tablek measurement
The heat transfer performance of the condenser is as follows:
Qevaporator measurement＝mChilled water measurementcChilled water(tChilled water intake measurement-tChilled water output measurement)
Evaporation temperature: the suction pressure of the compressor is used as the saturation pressure in the evaporator, and the approximate evaporation temperature t is obtained by looking up the tablee measurement
Compressor efficiency measurement:
wherein N isCompressor measuringIs composed ofMeasurement ofAnd inputting power by the unit.
COP measurement:
it should be noted that most of the chiller units can be unloaded for load operation, the energy-saving characteristic of the chiller units should be the reflection of the overall operation condition of the air conditioning unit rather than the full-load operation, and from the annual operation time of the chiller units, the 100% load operation time of the chiller units is not long, so that the chiller units must be comprehensively evaluated to analyze the partial load characteristic. In the case where the manufacturer does not provide a chiller part load performance curve, a typical chiller part load performance curve may be utilized, see FIG. 4. According to a curve of the input power of the water chilling unit changing along with the load rate, a relational formula of the input power of the water chilling unit and the load rate is obtained through fitting, and the fitting curve of the screw unit in the graph 4 is as follows:
N/Nrated value＝15.617-0.15568*(Q/QRated value)+0.01004*(Q/QRated value)2
Preferably, the chiller part load performance curve can also be obtained by operational measurements.
The difference between the outlet water of the cooling tower and the outdoor wet bulb temperature is not related to the outdoor wet bulb temperature, namely, the temperature t of any outdoor air wet bulbsIn the case of Δ tCooling tower0.26 ℃. Theoretical temperature t of cooling water leaving cooling towerw2 theory：
tw2 theory＝ts+ΔtCooling tower
Theoretical value of condensation temperature: t is tTheory of k＝tw2 theory+8
The difference between the condensation temperature and the cooling water inlet temperature is 8 ℃.
In general, the evaporation temperature is not changed. The theoretical value t of the condensation temperatureTheory of kTaken into the fitted curve above yields:
COPtheory of the invention/COPRated value＝1-0.022(tTheory of k-40)
By
Push away
Logarithmic mean temperature difference:
theoretical heat transfer capacity of the condenser: qTheory of condenser＝(KF)Condenser ratingΔtTheory of mk
By
To obtain
Compression mechanism theoretical power of compressor: n is a radical ofTheory of compressor＝QTheory of condenser-QTheory of evaporator
Fitting to obtain N according to the partial load performance curve of the water chilling unitTheory of the invention/NRated valueCurve N as a function of load factorTheory of the invention/NRated value＝f(Q/QRated value)。
According to the latitude and temperature difference of different regions, the annual power consumption is estimated. In this embodiment, the climate is estimated according to the climate of the middle and lower reaches of the Yangtze river. The refrigerating operation time of the air conditioner all the year around is calculated according to 150 days, and 100% of the design day is operated for 20 days, 80% of the design day is operated for 70 days, and 60% of the design day is operated for 60 days. The theoretical power consumption for one day was calculated as follows:
in the formula: qiη is the load provided by the chiller at the ith moment of the design dayLoad(s)Is the load factor, 100% design day ηLoad(s)Design daily load η ═ 1, 80%, and 60%Load(s)0.8 and ηLoad(s)＝0.6。
Theoretical refrigeration power consumption throughout the year:
assuming any operating conditions, energy efficiency ratio efficiency ηCOPDefined as the ratio of the measured value of the COP of the water chiller to the theoretical value of the COP of the water chiller in the measuring environment, i.e.
Thus calculating the annual refrigeration power consumption:
if the measurement under multiple working conditions can be realized, η can be obtainedCOPAnd the relation with the working condition, the annual refrigeration power consumption obtained by properly correcting and calculating the formula is more accurate.
Thus, the theoretical annual operating cost
In the formula: piIs the electricity price at time i, yuan/kWH.
Calculating annual operating costs from measured parameters
Year of investment recovery
In the formula: y is the investment recovery age of the replacement of the chiller, PInitial investmentIs the initial investment of the water chilling unit.
The investment recovery years and η are obtained from the two modesCOPIn relation to (2)
Where k is the ratio of initial investment to annual theoretical operating costs.
By determining the threshold for the recovery years of investment, the corresponding η can be foundCOPThreshold, refer to FIG. 5 when ηCOPLess than ηCOPAnd in the threshold, the energy consumption is higher, the refrigeration efficiency is low, and the replacement of a water chilling unit can be considered to reduce the energy consumption.
Diagnostic standard specification for cooling tower, compressor, condenser, evaporator, thermostatic expansion valve and chiller system:
if the heat exchange efficiency of the cooling tower is ηCooling tower< 95%, indicating the exchange of the cooling towerThe thermal efficiency does not reach the design value, and the thermal efficiency needs to be overhauled and maintained;
if the evaporator heat transfer efficiency ηQ evaporatorEfficiency η of < 85% or the product of evaporator heat transfer coefficient and heat transfer area(KF) evaporatorIf the heat exchange performance is not improved, the evaporator is tried to be overhauled or even replaced;
if the condenser heat transfer efficiency ηQ condenserEfficiency η of < 85% or the product of condenser heat transfer coefficient and heat transfer area(KF) condenserIf the heat exchange performance is not improved yet, the condenser is tried to be overhauled or even replaced;
if the compressor efficiency is poor delta ηCompressor with a compressor housing having a plurality of compressor bladesIf the temperature is more than 20%, the compressor is checked and maintained through the suction temperature, the exhaust temperature and the using amount of lubricating oil, and if the requirement is not met, the compressor is replaced;
if the superheat degree is equal to the return air pipe temperature-evaporation temperature, and if the superheat degree of the thermal expansion valve is not between 5 and 8 ℃, the thermal expansion valve is properly adjusted to enable the superheat degree to be in accordance with the temperature range.
If ηCOP＜ηCOPNote here that η is the case when the evaporator, condenser, compressor, etc. are all in efficiency, i.e. a single overhaul is acceptableCOP＜ηCOPThe condition of the threshold value is still met, which indicates that the water chilling units are not matched seriously, and the whole water chilling unit must be replaced at the moment; when the evaporator, the condenser, the compressor and the like do not accord with the efficiency condition, namely, the single overhaul is unqualified, the whole water chilling unit is possibly in an aging state completely, and the whole water chilling unit is required to be replaced.
Example 2
Referring to fig. 6, for the water chiller energy efficiency diagnostic system provided in this embodiment, the water chiller energy efficiency diagnostic method according to the foregoing embodiment can be applied to the water chiller energy efficiency diagnostic system, and includes a first calculating module, a second calculating module, a measuring module, and a diagnostic module.
The first calculation module is used for calculating the energy efficiency ratio of the water chilling unit, the efficiency of the compressor, the heat transfer capacity of the condenser, the logarithmic mean temperature difference of the condenser, the product of the heat transfer coefficient and the heat transfer area of the condenser, the heat transfer capacity of the evaporator, the logarithmic mean difference of the evaporator, the product of the heat transfer coefficient and the heat transfer area of the evaporator, and the temperature difference between the outlet water of the cooling tower and the outdoor wet bulb. The second calculation module is logically connected with the first calculation module and used for calculating annual power consumption, annual operating cost, investment recovery age, an energy efficiency ratio efficiency threshold, cooling tower heat exchange efficiency, evaporator heat transfer efficiency, the product efficiency of the evaporator heat transfer coefficient and the heat transfer area, condenser heat transfer efficiency, the product efficiency of the condenser heat transfer coefficient and the heat transfer area, compressor efficiency difference and superheat degree. And the measuring module is logically connected with the first calculating module and is used for measuring specific operation data of the cooling tower, the compressor, the condenser, the evaporator and the thermal expansion valve. The diagnosis module is connected with the first calculation module and the second calculation module and is used for diagnosing the cooling tower, the compressor, the condenser, the evaporator, the thermostatic expansion valve and the water chilling unit system.
In this embodiment, the first calculation module, the second calculation module and the diagnosis module may be three computers or a computer integrating functions of the three modules, a calculation formula provided in the water chiller unit energy efficiency diagnosis method is converted into a computer program, and by inputting relevant rated parameters and measurement data, results to be calculated or compared in the first calculation module, the second calculation module and the diagnosis module can be quickly obtained by the computer program, so that complexity and error caused by manual calculation are avoided.
The operation process of the water chilling unit energy efficiency diagnosis system is as follows: the measurement module transmits the measured data to the first calculation module, the first calculation module respectively calculates parameter values under rated working conditions and measured values under actual operation, and the first calculation module and the second calculation module transmit the calculated results to the diagnosis module for diagnosis to obtain diagnosis results. The measuring module comprises a thermometer, a pressure gauge, a power meter and a flowmeter.
It should be noted that various measuring instruments should be selected according to the usage scenario. The water temperature test generally selects a glass tube thermometer, and the installation position is usually placed in reserved sockets of various pipelines. The thermometers with proper measuring range and precision are selected to be uniformly installed before the system runs, and meanwhile, the measuring precision is guaranteed. The thermometer which is damaged or the precision of which can not meet the requirement is replaced in time. If the field condition does not allow replacement, such as system water leakage, other measuring instruments, such as an infrared thermometer, a self-recording thermometer, etc., should be used.
The pressure gauge can be selected from a spring tube pressure gauge, the water side evaporator, the condenser inlet and outlet and the water pump inlet and outlet of the common water chilling unit are respectively provided with a self-contained pressure gauge, and the measuring range and the precision are suitable according to local conditions. The flowmeter is an ultrasonic flowmeter, which is a novel instrument developed by utilizing the characteristic that the propagation speed of ultrasonic waves in a fluid can change along with the flow velocity of the measured fluid. When the ultrasonic flowmeter is used for measurement, two modes of reflection and diagonal can be provided. Generally, according to introduction of a product use specification, compared with other flowmeters, the ultrasonic flowmeter with the proper measurement mode is selected and used in different occasions, the ultrasonic flowmeter has more superiority in engineering test, only needs the contact of a probe and a pipe wall, cannot damage the existing pipeline, does not interfere a flow field, has wider application range, and can be used for flow measurement of various media with the pipe diameter of 20-5000 mm.
Energy efficiency diagnosis application of the water chilling unit:
jiangsu labor-saving commercial electricity price: 0.8601 yuan/kwh. An LSBLG420 type water-cooling screw type water chilling unit is adopted in a certain project of Jiangsu province, and relevant parameters are as follows: refrigerating capacity 419KW, refrigerating input power 93KW and evaporator water flow 72.1m3Water flow rate of condenser 88m3The rated working condition is that the inlet temperature of chilled water is 12 ℃, the outlet temperature is 7 ℃, the inlet temperature of cooling water is 32 ℃ and the outlet temperature is 37 ℃. The evaporator temperature is 4 ℃, the condensation temperature is 40 ℃, the re-cooling degree is 3 ℃ and the superheat degree is 5 ℃ under the rated working conditions.
Measurement data: the temperature of cooling water entering the cooling tower is 38 ℃, the temperature of cooling water exiting the cooling tower is 33 ℃, the temperature of outdoor air wet bulb is 32.74 ℃, the suction pressure of a compressor is 0.6MPa, the exhaust pressure of the compressor is 1.5MPa, the input power is 115.2kW, and the cooling water enters the cooling towerThe temperature of the cooling water entering the condenser is 33 ℃, the temperature of the cooling water exiting the condenser is 38 ℃, and the flow rate of the cooling water is 85m3The temperature of the chilled water entering the evaporator is 11.8 ℃, the temperature of the chilled water leaving the evaporator is 7 ℃, and the flow rate of the chilled water is 70m3The suction pressure of the compressor was 0.6MPa (saturation pressure in evaporator, table look-up gave the approximate evaporation temperature).
Rated parameter calculation results: rated COP of water chilling unitRated value＝4.51，h1＝411kJ/kg，h2＝438kJ/kg，h4＝h5＝246kJ/kg，COPTheory of nominalTotal compressor efficiency η ═ 6.11Compressor with a compressor housing having a plurality of compressor blades0.738; heat transfer capacity Q of condenserCondenser512KW, 40 deg.C of condensation temperature, logarithmic mean temperature difference delta t of condensermk5.1 deg.C, the product of the heat transfer coefficient and the heat transfer area of the condenser (KF)Condenser rating100.4 kW/deg.c; heat transfer capacity of evaporator QEvaporator with a heat exchanger419KW, mean logarithmic evaporator temperature difference Δ tmd5.1 deg.C, the product of evaporator heat transfer coefficient and heat transfer area (KF)Evaporator rating＝82.16kW/℃。
η (measured value under non-rated working condition) heat exchange efficiency of cooling towerCooling tower0.951, cooling water inlet temperature tw2 theoryTheoretical value of condensation temperature t 33 ℃Theory of k41 ℃ (the difference between the condensation temperature and the cooling water inlet temperature is 8 ℃), and the cooling water outlet temperature tw1 theory38.05 deg.C, logarithmic mean temperature difference theory value delta tTheory of mkTheoretical value (KF) of the product of heat transfer coefficient and heat transfer area of condenser at 5.06 deg.CTheory of condenser100.4 kW/deg.c; looking up the table to obtain the measured value t of the condensing temperaturek measurementTheoretical value Q of heat transfer capacity of condenser at 41.1 DEG CCondenser measurement508 KW; logarithmic mean temperature difference measurement of condenser Δ tmk measurementCondenser heat transfer measurement Q at 5.22 ℃Condenser measurementMeasured as the product of the heat transfer coefficient and the heat transfer area of the condenser (KF) 495.8KWCondenser measurement＝95kW/℃。
Theoretical value Q of heat transfer capacity of evaporatorEvaporator measurement＝414.1KW，,ΔtTheory of e5.1 deg.C, evaporator transferTheoretical value of heat coefficient multiplied by heat transfer area (KF)Theory of evaporator81.2 kW/deg.c; looking up the table to obtain the measured value t of the evaporation temperaturee measurement4.4 ℃, evaporator heat transfer performance measurement: Δ te measurement4.59 deg.C, measured evaporator heat transfer QEvaporator measurementMeasured value (KF) of the product of evaporator heat transfer coefficient and heat transfer area (366.2 KW)Evaporator measurement＝979.78kW/℃。
Theoretical power N of compressorTheory of compressor93.9KW, input power measurement NCompressor measurement115.2 KW; the water chilling unit system: COPTheory of the invention/COPRated value＝0.978；COPTheory of the invention＝4.41；ηCompressor with a compressor housing having a plurality of compressor blades0.738; COP measurement: COPMeasuring＝3.18，ηCOP＝0.721。
Specific annual power consumption and operating cost calculations are shown in table 1:
table 1: energy consumption and running cost calculating table
And (3) diagnosis results:
ηcooling tower95.1 percent or more than 95 percent, and the heat exchange efficiency of the cooling tower reaches a design value;
ηq condenser＝97.6％>85％,η(KF) condenser＝94.6％>85 percent, which indicates that the heat exchange performance of the condenser is not low, and the condenser is not required to be overhauled temporarily;
ηq evaporator＝88.4％>85％，η(KF) evaporator＝98.3％>85 percent, which indicates that the heat exchange performance of the evaporator is not low and the evaporator does not need to be overhauled;
Δηcompressor with a compressor housing having a plurality of compressor blades1.7%, which indicates that the efficiency attenuation of the compressor is not serious;
ηCOP<ηCOPthe threshold value, the actual investment recovery year Y is 4.9 years, which indicates the water chilling unit COP attenuates more, and the unit can be replaced. The investment recovery period for replacing the unit is less than 5 years.
The COP attenuation of the whole water chilling unit is not caused by the attenuation of the operation function of a certain component, but is the result of the combined attenuation. In this case, it is recommended to replace the chiller to indicate that the operating conditions of the various components have not matched.
It is important to note that the construction and arrangement of the present application as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in this application. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of this invention. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present inventions. Therefore, the present invention is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims.
Moreover, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not be described (i.e., those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the invention).
It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (8)
1. A water chilling unit energy efficiency diagnosis method is characterized in that: comprises the following steps of (a) carrying out,
obtaining rated parameters, obtaining the refrigerating capacity and input power of the water chilling unit according to the type of the water chilling unit, and obtaining the temperature of an evaporator, the supercooling degree, the superheat degree, the inlet water temperature of chilled water, the outlet water temperature, the inlet water temperature of cooling water and the outlet water temperature under rated working conditions according to a use scene;
calculating rated parameters, and calculating the energy efficiency ratio of the water chilling unit, the efficiency of a compressor, the heat transfer capacity of a condenser, the logarithmic mean temperature difference of the condenser, the product of the heat transfer coefficient of the condenser and the heat transfer area, the heat transfer capacity of an evaporator, the logarithmic mean difference of the evaporator, the product of the heat transfer coefficient of the evaporator and the heat transfer area, and the temperature difference between the outlet water of a cooling tower and an outdoor wet bulb under the rated working condition according to the obtained rated parameters;
measuring actual operation data, including operation data of a cooling tower, a compressor, a condenser, an evaporator and a thermal expansion valve in the components of the water chiller;
calculating actual operation parameters, calculating the heat transfer capacity of the condenser, the logarithmic average temperature difference measured by the condenser, the product of the heat transfer coefficient and the heat transfer area of the condenser, the heat transfer capacity of the evaporator, the logarithmic average difference of the evaporator, the product of the heat transfer coefficient and the heat transfer area of the evaporator under actual operation according to the measured actual operation data, and further calculating the energy efficiency ratio of the water chilling unit, the input power of the compressor and the measured efficiency of the compressor;
and (3) energy efficiency diagnosis of the water chilling unit, respectively diagnosing the cooling tower, the compressor, the condenser, the evaporator and the thermal expansion valve, estimating annual power consumption and annual operation cost, calculating the investment recovery year limit, determining an energy efficiency ratio efficiency threshold value, and diagnosing the water chilling unit system.
2. The chiller unit energy efficiency diagnostic method according to claim 1, characterized in that: the measurement of specific operational data of the cooling tower, the compressor, the condenser, the evaporator and the thermostatic expansion valve comprises,
measuring the temperature of cooling water entering the cooling tower, the temperature of cooling water exiting the cooling tower and the outdoor air wet bulb temperature;
measuring the suction pressure of the compressor, the exhaust pressure of the compressor and the input power of the water chilling unit;
measuring the temperature of cooling water entering the condenser, the temperature of cooling water exiting the condenser, and the flow of cooling water through the condenser;
measuring the temperature of the chilled water entering the evaporator, the temperature of the chilled water exiting the evaporator and the flow rate of the chilled water;
the temperature of a return air pipe between the evaporator and the compressor is measured.
3. The water chiller unit energy efficiency diagnosis method according to claim 1 or 2, characterized in that: the calculation formula of the investment recovery age is
Wherein Y is the investment recovery time limit for replacing the water chilling unit, P is the initial investment of the water chilling unit,
determining the energy efficiency ratio efficiency threshold value:
wherein, ηCOPFor energy efficiency ratio efficiency, the ratio of the measured value of the COP of the water chilling unit to the theoretical value of the COP of the water chilling unit under the measuring environment is defined, namely
k is the ratio of the initial investment to the annual theoretical operating cost.
4. The chiller unit energy efficiency diagnostic method according to claim 3, characterized in that: the diagnostic standard of the cooling tower, the compressor, the condenser, the evaporator, the thermostatic expansion valve and the water chilling unit system is as follows:
if the heat exchange efficiency of the cooling tower is ηCooling towerIf less than 95%, overhauling and maintaining the cooling tower;
if the evaporator heat transfer efficiency ηQ evaporatorEfficiency η of < 85% or the product of evaporator heat transfer coefficient and heat transfer area(KF) evaporatorIf less than 85%, the evaporator is overhauled or replaced;
if the condenser heat transfer efficiency ηQ condenserEfficiency η of < 85% or the product of condenser heat transfer coefficient and heat transfer area(KF) condenserIf less than 85%, the evaporator is overhauled or replaced;
if the compressor efficiency is poor delta ηCompressor with a compressor housing having a plurality of compressor bladesMore than 20%, and repairing or replacing the compressor;
if the superheat degree is equal to the temperature of the air return pipe-evaporation temperature, and if the superheat degree of the thermostatic expansion valve is not between 5 and 8 ℃, proper adjustment is needed;
if ηCOP＜ηCOPAnd (5) replacing the water chilling unit according to the threshold value.
5. The chiller unit energy efficiency diagnostic method according to claim 4, characterized in that: the calculation formula of the heat exchange efficiency of the cooling tower is
Wherein, tw1、tw2、tsThe temperature of cooling water entering and exiting the cooling tower and the temperature of outdoor air wet bulb are respectively set;
the compressor efficiency difference is expressed by a formula of delta ηCompressor with a compressor housing having a plurality of compressor blades＝ηTheory of compressor-ηCOP，ηTheory of compressorIs the theoretical efficiency of the compressor.
6. A water chilling unit energy efficiency diagnostic system is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
the first calculation module is used for calculating the energy efficiency ratio of the water chilling unit, the efficiency of the compressor, the heat transfer capacity of the condenser, the logarithmic mean temperature difference of the condenser, the product of the heat transfer coefficient and the heat transfer area of the condenser, the heat transfer capacity of the evaporator, the logarithmic mean difference of the evaporator, the product of the heat transfer coefficient and the heat transfer area of the evaporator and the temperature difference between the outlet water of the cooling tower and the outdoor wet bulb;
the second calculation module is logically connected with the first calculation module and is used for calculating annual power consumption, annual operating cost, investment recovery age, an energy efficiency ratio efficiency threshold, cooling tower heat exchange efficiency, evaporator heat transfer efficiency, the product efficiency of the evaporator heat transfer coefficient and the heat transfer area, condenser heat transfer efficiency, the product efficiency of the condenser heat transfer coefficient and the heat transfer area, compressor efficiency difference and superheat degree;
the measuring module is logically connected with the first calculating module and used for measuring specific operation data of the cooling tower, the compressor, the condenser, the evaporator and the thermal expansion valve;
and the diagnosis module is connected with the first calculation module and the second calculation module and is used for diagnosing the cooling tower, the compressor, the condenser, the evaporator, the thermostatic expansion valve and the water chilling unit system.
7. The chiller unit energy efficiency diagnostic system of claim 6, wherein: the measurement module transmits the measured data to the first calculation module, the first calculation module respectively calculates parameter values under rated working conditions and measured values under actual operation, and the first calculation module and the second calculation module transmit the calculated results to the diagnosis module for diagnosis to obtain diagnosis results.
8. The chiller unit energy efficiency diagnostic system according to claim 6 or 7, characterized in that: the measuring module comprises a thermometer, a pressure gauge, a power meter and a flowmeter.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113281074A (en) * | 2021-05-17 | 2021-08-20 | 青岛海信日立空调系统有限公司 | Performance degradation diagnosis method for condenser and evaporator of water chilling unit |
| CN113739363A (en) * | 2021-09-23 | 2021-12-03 | 广东电网有限责任公司 | Method, device and equipment for determining electric quantity for air conditioner and storage medium |
| CN114396731A (en) * | 2021-12-30 | 2022-04-26 | 青岛海信日立空调系统有限公司 | Refrigerating unit |
| WO2024012545A1 (en) * | 2022-07-13 | 2024-01-18 | 青岛海信日立空调系统有限公司 | Air conditioning system and method for determining energy efficiency ratio thereof |
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2020
- 2020-06-09 CN CN202010516345.8A patent/CN111623570A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113281074A (en) * | 2021-05-17 | 2021-08-20 | 青岛海信日立空调系统有限公司 | Performance degradation diagnosis method for condenser and evaporator of water chilling unit |
| CN113281074B (en) * | 2021-05-17 | 2023-01-13 | 青岛海信日立空调系统有限公司 | Performance degradation diagnosis method for condenser and evaporator of water chilling unit |
| CN113739363A (en) * | 2021-09-23 | 2021-12-03 | 广东电网有限责任公司 | Method, device and equipment for determining electric quantity for air conditioner and storage medium |
| CN114396731A (en) * | 2021-12-30 | 2022-04-26 | 青岛海信日立空调系统有限公司 | Refrigerating unit |
| WO2024012545A1 (en) * | 2022-07-13 | 2024-01-18 | 青岛海信日立空调系统有限公司 | Air conditioning system and method for determining energy efficiency ratio thereof |
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