CN113281074B - Performance degradation diagnosis method for condenser and evaporator of water chilling unit - Google Patents

Performance degradation diagnosis method for condenser and evaporator of water chilling unit Download PDF

Info

Publication number
CN113281074B
CN113281074B CN202110535668.6A CN202110535668A CN113281074B CN 113281074 B CN113281074 B CN 113281074B CN 202110535668 A CN202110535668 A CN 202110535668A CN 113281074 B CN113281074 B CN 113281074B
Authority
CN
China
Prior art keywords
condenser
evaporator
heat transfer
water
pressure drop
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202110535668.6A
Other languages
Chinese (zh)
Other versions
CN113281074A (en
Inventor
石靖峰
王占伟
陈见兴
王林
谈莹莹
曹艺飞
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.)
Henan University of Science and Technology
Qingdao Hisense Hitachi Air Conditioning System Co Ltd
Original Assignee
Henan University of Science and Technology
Qingdao Hisense Hitachi Air Conditioning System 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 Henan University of Science and Technology, Qingdao Hisense Hitachi Air Conditioning System Co Ltd filed Critical Henan University of Science and Technology
Priority to CN202110535668.6A priority Critical patent/CN113281074B/en
Publication of CN113281074A publication Critical patent/CN113281074A/en
Application granted granted Critical
Publication of CN113281074B publication Critical patent/CN113281074B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • G01M99/008—Subject matter not provided for in other groups of this subclass by doing functionality tests
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D21/00—Measuring or testing not otherwise provided for
    • G01D21/02—Measuring two or more variables by means not covered by a single other subclass

Abstract

The invention provides a method for diagnosing performance degradation of a condenser and an evaporator of a water chilling unit, which comprises the following steps: s1: acquiring the operating values of a plurality of groups of characteristic parameters of a water chilling unit under normal working conditions; s2: establishing a reference value model of the comprehensive heat transfer coefficient of the condenser and the evaporator; s3: constructing a reference value model of the water side pressure drop of the condenser and the evaporator; s4: obtaining and comparing the actual value and the reference value of the comprehensive heat transfer coefficient of the condenser and the evaporator to obtain the conclusion whether the heat transfer performance of the condenser and the evaporator is deteriorated; s5: obtaining and comparing the actual values of the pressure drop of the water sides of the condenser and the evaporator with a reference value to obtain a conclusion whether the flow performance of the condenser and the evaporator is deteriorated; the purpose of avoiding the inefficient operation and the barrier operation of the condenser and the evaporator is achieved by effectively diagnosing the performance degradation of the condenser and the evaporator, so that the operation energy consumption of a water chilling unit is saved, the operation service lives of the condenser and the evaporator are prolonged, the method is simple, the calculation is convenient, and the difficulty of model construction is greatly reduced.

Description

Performance degradation diagnosis method for condenser and evaporator of water chilling unit
Technical Field
The invention relates to the field of water chilling units, in particular to a method for diagnosing performance degradation of a condenser and an evaporator of a water chilling unit.
Background
The water chilling unit is a main energy consumption device in an air conditioning system, and the condenser and the evaporator are the most main heat exchange components in the water chilling unit. When the heat transfer performance or the flow performance of the condenser and the evaporator is deteriorated, if the deterioration is discovered and eliminated in time, the reduction of the heat transfer performance will cause the reduction of the heat exchange efficiency, and the reduction of the flow performance will cause the increase of the power consumption of the water pump, both of which will reduce the working performance of the condenser and the evaporator, reduce the working life of the condenser and the evaporator, and cause the waste of energy. The method has the advantages that the condenser and the evaporator of the water chilling unit are monitored, whether the performance of the condenser and the evaporator is degraded or not is diagnosed, the performance degradation faults of the condenser and the evaporator are timely found and eliminated, and the method has important significance for reliable operation of the condenser and the evaporator in the water chilling unit.
In a water chilling unit, the operation reliability of a system is generally concerned, the operation stability of a heat exchanger is less concerned, the comprehensive heat transfer coefficient is an effective characteristic parameter indicating the heat transfer performance of a condenser and an evaporator, the water side pressure drop of the condenser and the evaporator is an effective characteristic parameter indicating the flow performance, the physical model of the condenser and the evaporator is difficult to construct accurately, and the internal structure parameters are difficult to obtain.
Disclosure of Invention
The present invention solves at least one of the technical problems of the related art to some extent. For this purpose,
according to an embodiment of the present disclosure, a method for diagnosing performance degradation of a condenser and an evaporator of a chiller is provided, which includes:
s1: acquiring the running values of a plurality of groups of characteristic parameters of a water chilling unit under normal working conditions;
s2: establishing a reference value model of the comprehensive heat transfer coefficient of the condenser and the evaporator;
s3: constructing a reference value model of the water side pressure drop of the condenser and the evaporator;
s4: obtaining and comparing the actual value and the reference value of the comprehensive heat transfer coefficient of the condenser and the evaporator to obtain the conclusion whether the heat transfer performance of the condenser and the evaporator is deteriorated;
s5: and obtaining and comparing the actual values of the water side pressure drops of the condenser and the evaporator with a reference value to obtain a conclusion whether the flow performances of the condenser and the evaporator are degraded or not.
The condenser and the evaporator are effectively monitored, the performance degradation of the condenser and the evaporator is effectively diagnosed, and the purposes of avoiding the inefficient operation and the barrier operation of the condenser and the evaporator are achieved, so that the operation energy consumption of a water chilling unit is saved, the operation service lives of the condenser and the evaporator are prolonged, meanwhile, the method for determining the comprehensive heat transfer coefficient and the water side pressure drop of the condenser and the evaporator is simple and convenient to calculate, and the difficulty of model construction is greatly reduced.
According to an embodiment of the present disclosure, the step S2 specifically includes:
s21: determining the heat absorption capacity of cooling water in the condenser, the logarithmic mean temperature difference of the condenser, the heat release capacity of frozen water in the evaporator and the logarithmic mean temperature difference of the evaporator according to the characteristic parameters obtained in the step S1;
s22: determining the comprehensive heat transfer coefficient KF of the condenser from the heat absorption amount of the cooling water in the condenser and the logarithmic mean temperature difference of the condenser determined in step S21 c Determining the comprehensive heat transfer coefficient KF of the evaporator from the heat release amount of the freezing water in the evaporator and the logarithmic mean temperature difference of the evaporator determined in the step S21 e ；
S23: constructing a comprehensive heat transfer coefficient reference value model of the condenser and a comprehensive heat transfer coefficient reference value model of the evaporator according to the comprehensive heat transfer coefficients of the condenser and the evaporator corresponding to the multiple groups of characteristic parameters, wherein the adopted formulas are as follows:
KF c ＝f(T k ,T e ,f r )
KF e ＝f(T k ,T e ,f r )
wherein, T k And T e Respectively representing the condensation temperature and the evaporation temperature, f r And a load rate representing the operation of the chiller.
The comprehensive heat transfer coefficient is used as a characteristic parameter for indicating the heat transfer performance of the evaporator and the condenser, the heat transfer performance of the evaporator and the condenser can be effectively detected, and the reference value model of the comprehensive heat transfer coefficient is constructed to accurately obtain the reference value.
According to the embodiment of the disclosure, in the step S23, the mapping relationship between the comprehensive heat transfer coefficient and the condensation temperature, the evaporation temperature and the load factor is established by a least square method, the least square model is trained by the operation value of the characteristic parameter under the normal working condition obtained in the step S1, the regression coefficient in the model is obtained, and the model with the comprehensive heat transfer coefficient reference value is determined.
According to an embodiment of the present disclosure, the step S3 specifically includes:
s31: determining the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side according to the characteristic parameters obtained in the step S1;
s32: determining the wall temperature of the condenser and the wall temperature of the evaporator according to the characteristic parameters, the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side obtained in the step S1;
s33: determining the cooling water side pressure drop of the condenser and the cooling water side pressure drop of the evaporator according to the characteristic parameters, the condenser pipe wall temperature and the evaporator pipe wall temperature which are obtained in the step S1;
s34: according to the water side pressure drop of the condenser and the evaporator under the normal working condition, a condenser water side pressure drop reference value model and an evaporator water side pressure drop reference value model are constructed, and the adopted formulas are as follows:
ΔP c ＝f(T k ,T e ,f r )
ΔP e ＝f(T k ,T e ,f r )
wherein, T k And T e Respectively representing the condensation temperature and the evaporation temperature, f r And a load rate representing the operation of the chiller.
The water side pressure drop is used as a characteristic parameter for indicating the flowing performance of the evaporator and the condenser, the flowing performance of the evaporator and the condenser can be effectively detected, and the reference value model of the water side pressure drop can be constructed to accurately obtain the reference value.
According to the embodiment of the disclosure, in the step S34, a mapping relation between the water side pressure drop and the condensing temperature, the evaporating temperature and the load factor is established based on a least square method, the least square model is trained through the operation value of the characteristic parameter under the normal working condition obtained in the step S1, the regression coefficient in the model is obtained, and the water side pressure drop reference value model is determined.
According to an embodiment of the present disclosure, the step S4 specifically includes:
s41: when the water chilling unit runs, collecting the running values of the characteristic parameters collected in the step S1 in real time;
s42: inputting the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41 into a reference value model of the comprehensive heat transfer coefficient of the condenser and the evaporator to obtain a reference value of the comprehensive heat transfer coefficient of the condenser and the evaporator;
s43: calculating an actual value of the comprehensive heat transfer coefficient of the condenser and the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
s44: judging whether the reference value of the comprehensive heat transfer coefficient of the condenser obtained in the step S42 is obviously larger than the actual value obtained in the step S43 or not based on a significance detection method in statistics, if so, obtaining the conclusion that the heat exchange performance of the condenser is degraded, otherwise, obtaining the conclusion that the heat exchange performance of the condenser is not degraded; and judging whether the reference value of the comprehensive heat transfer coefficient of the evaporator obtained in the step S42 is obviously larger than the actual value obtained in the step S43, if so, obtaining the conclusion that the heat exchange performance of the evaporator is degraded, otherwise, obtaining the conclusion that the heat exchange performance of the evaporator is not degraded.
And the actual value of the comprehensive heat transfer coefficient and the reference value thereof are obtained, the calculation is convenient, and the actual value of the comprehensive heat transfer coefficient is compared with the reference value thereof to diagnose the degradation of the heat exchange performance of the condenser and the evaporator and form the conclusion whether the performance degradation occurs.
According to an embodiment of the present disclosure, the step S43 specifically includes:
s431: determining the heat absorption capacity of the cooling water in the condenser and the heat release capacity of the freezing water in the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
s432: determining the logarithmic mean temperature difference of the condenser and the logarithmic mean temperature difference of the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
s433: determining the integrated heat transfer coefficient KF of the condenser from the heat absorption amount of the cooling water determined in step S431 and the logarithmic mean temperature difference of the condenser determined in step S432 based on the conservation of energy c The integrated heat transfer coefficient value of the condenser is the integrated heat transfer coefficient actual value of the condenser, and the integrated heat transfer coefficient KF of the evaporator is determined by the heat release amount of the chilled water determined in step S431 and the logarithmic mean temperature difference of the evaporator determined in step S432 e And the comprehensive heat transfer coefficient value of the evaporator is the actual comprehensive heat transfer coefficient value of the evaporator.
According to an embodiment of the present disclosure, the step S5 specifically includes:
s51: when the water chilling unit runs, collecting the running values of the characteristic parameters collected in the step S1 in real time;
s52: inputting the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51 into a reference value model of the water side pressure drop of the condenser and the evaporator to obtain a reference value of the water side pressure drop of the condenser and the evaporator;
s53: calculating actual values of the water side pressure drops of the condenser and the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51;
s54: judging whether the reference value of the water side pressure drop of the condenser obtained in the step S52 is obviously larger than the actual value obtained in the step S53 or not based on a significance detection method in statistics, if so, obtaining the conclusion that the flow performance of the condenser is degraded, otherwise, obtaining the conclusion that the flow performance of the condenser is not degraded; and judging whether the reference value of the water side pressure drop of the evaporator obtained in the step S42 is obviously larger than the actual value obtained in the step S53, if so, obtaining the conclusion that the flow performance of the evaporator is degraded, otherwise, obtaining the conclusion that the flow performance of the evaporator is not degraded.
And the actual value of the pressure drop on the water side and the reference value thereof are obtained, the calculation is convenient, and the actual value of the pressure drop on the water side is compared with the reference value thereof, so that the flow performance degradation of the condenser and the evaporator is diagnosed, and the conclusion whether the performance degradation occurs is formed.
According to an embodiment of the present disclosure, in step S53, specifically:
s531: determining the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51;
s532: determining the wall temperature of the condenser and the wall temperature of the evaporator according to the real-time characteristic parameters of the condenser and the evaporator, the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side obtained in the step S51;
s533: and determining the cooling water side pressure drop of the condenser and the cooling water side pressure drop of the evaporator according to the real-time characteristic parameters of the condenser and the evaporator, the wall temperature of the condenser and the wall temperature of the evaporator, which are obtained in the step S51, wherein the cooling water side pressure drop value of the condenser is the actual cooling water side pressure drop value of the condenser, and the cooling water side pressure drop value of the evaporator is the actual cooling water side pressure drop value of the evaporator.
According to the embodiment of the disclosure, the characteristic parameters in step S1 include cooling water flow, cooling water inlet water temperature, cooling water outlet water temperature, condensation temperature of the condenser, chilled water flow, chilled water inlet water temperature, chilled water outlet water temperature, evaporation temperature of the evaporator, evaporation pressure, condensation pressure, and structural parameters of the evaporator and the condenser, where the structural parameters of the evaporator and the condenser include heat exchange area, fouling thermal resistance, pipe inner diameter, pipe outer diameter, pipe wall thickness, pipe thermal conductivity, pipe pass number, and pipe length.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flow chart of a chiller condenser and evaporator performance degradation diagnostic method according to an embodiment of the present disclosure.
Detailed Description
The invention is described in detail below by way of exemplary embodiments. It should be understood, however, that elements, structures, and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
The invention provides a method for diagnosing the performance degradation of a condenser and an evaporator of a water chilling unit, which comprises the following steps with reference to figure 1:
s1: acquiring the running values of a plurality of groups of characteristic parameters of a water chilling unit under normal working conditions;
specifically, when the water chilling unit operates under a normal working condition, multiple data acquisition is performed at a certain time interval to obtain the operating values of multiple groups of characteristic parameters, the time interval can be ts, the number of groups of characteristic parameters can be N, wherein t can be 10, and N can be 500.
The characteristic parameters mainly comprise: the system comprises a condenser, a cooling water inlet, a cooling water outlet, a condenser, a freezing water flow, a chilled water inlet, a chilled water outlet, an evaporator, an evaporation pressure, a condensation pressure and structural parameters of the evaporator and the condenser, wherein the structural parameters of the evaporator and the condenser comprise heat exchange area, dirt thermal resistance, pipe inner diameter, pipe outer diameter, pipe wall thickness, pipe heat conductivity coefficient, pipe pass number and pipe length. Where the fouling resistance can include an in-tube fouling resistance and an out-of-tube fouling resistance, it is of course also possible to measure the refrigerant outlet temperature of the condenser, the refrigerant inlet temperature of the condenser, the refrigerant outlet temperature of the evaporator, the refrigerant inlet temperature of the evaporator. The data can be obtained through an actual water chilling unit, or the data can be obtained by building a test bench and simulating the normal operation of the water chilling unit through the test bench.
S2: establishing a reference value model of the comprehensive heat transfer coefficient of the condenser and the evaporator;
the step S2 specifically includes the following steps:
s21: according to the characteristic parameters obtained in the step S1, determining the heat absorption capacity of the cooling water in the condenser, the logarithmic mean temperature difference of the condenser, the heat release capacity of the frozen water in the evaporator and the logarithmic mean temperature difference of the evaporator;
specifically, according to the characteristic parameters obtained in the step S1, the heat absorption capacity of the cooling water in the condenser is determined by the cooling water flow rate, the constant-pressure specific heat capacity of the cooling water at the qualitative temperature, the cooling water inlet water temperature and the cooling water outlet water temperature, the logarithmic mean temperature difference of the condenser is determined by the cooling water inlet water temperature, the cooling water outlet water temperature and the condensation temperature of the condenser, the heat release capacity of the chilled water in the evaporator is determined by the chilled water flow rate, the constant-pressure specific heat capacity of the chilled water at the qualitative temperature, the chilled water inlet water temperature and the chilled water outlet water temperature, and the logarithmic mean temperature difference of the evaporator is determined by the chilled water inlet water temperature, the chilled water outlet water temperature and the evaporation temperature of the evaporator;
specifically, the calculation formula is as follows:
Q c ＝m c c p (T co -T ci ) (1)
ΔT mc ＝((T k -T co )-(T k -T ci )/ln((T k -T co )/(T k -T ci )) (2)
wherein m is c The flow rate of cooling water is Kg/s, c pc The specific heat capacity of the cooling water at a constant pressure at a qualitative temperature is represented by KJ/(Kg. Multidot.K), T co And T ci Respectively cooling water outlet temperature and cooling water inlet temperature, wherein the unit is K and Q c Is the heat absorption capacity of cooling water in the condenser, and has the unit of KW and T k Is the condensing temperature of the condenser and has the unit of K, delta T mc Is the logarithmic mean temperature difference of the condenser, with the unit being K;
Q e ＝m l c pe (T eo -T ei ) (3)
ΔT me ＝((T ei -T e )-(T eo –T e )/ln((T ei -T e )/(T eo –T e )) (4)
wherein m is l The unit is the flow of the chilled water and is Kg/s; c. C pe The specific heat capacity at constant pressure of the frozen water at a qualitative temperature is represented by KJ/(Kg. K); t is eo And T ei Respectively providing chilled water outlet water temperature and cooling water inlet water temperature, wherein the unit is K; q e Is the heat release of the chilled water in the evaporator, in KW; t is e Is the evaporation temperature of the evaporator and has the unit of K, delta T me Is the logarithmic mean temperature difference of the evaporator in K.
The method comprises the steps of determining the qualitative temperature of a cooling water side through the average water temperature of a cooling water inlet and an average water temperature of a cooling water outlet, determining the specific heat capacity of the cooling water at the constant pressure under the qualitative temperature through the qualitative temperature of the cooling water side, determining the qualitative temperature of a freezing water side through the average water temperature of a freezing water inlet and the average water temperature of the freezing water outlet, and determining the specific heat capacity of the freezing water at the constant pressure under the qualitative temperature through the qualitative temperature of the freezing water side.
S22: determining the comprehensive heat transfer coefficient KF of the condenser from the heat absorption amount of the cooling water in the condenser and the logarithmic mean temperature difference of the condenser determined in step S21 based on the conservation of energy c Determining the comprehensive heat transfer coefficient KF of the evaporator from the heat release amount of the freezing water in the evaporator and the logarithmic mean temperature difference of the evaporator determined in the step S21 e ；
The specific formula is as follows:
KF c ＝10 3 Q c /ΔT mc (5)
KF e ＝10 3 Q e /ΔT me (6)
wherein, KF c Is the comprehensive heat transfer coefficient of the condenser, and the unit is W/K, KF e The comprehensive heat transfer coefficient of the evaporator is in W/K.
S23: constructing a comprehensive heat transfer coefficient reference value model of the condenser and a comprehensive heat transfer coefficient reference value model of the evaporator according to the comprehensive heat transfer coefficients of the condenser and the evaporator corresponding to the multiple groups of characteristic parameters,
specifically, the formula used is as follows:
KF c ＝f(T k ,T e ,f r ) (7)
KF e ＝f(T k ,T e ,f r ) (8)
wherein, T k And T e Respectively representing the condensation temperature of the condenser and the evaporation temperature of the evaporator, f r And the load rate of the running of the water chilling unit is represented.
Specifically, a mapping relation between the comprehensive heat transfer coefficient and the condensing temperature, the evaporating temperature and the load factor is established by a least square method, specifically, the least square model is trained through the running values of the characteristic parameters under 500 groups of normal working conditions, which are obtained in S1, so that the regression coefficient in the model is obtained, and the model of the comprehensive heat transfer coefficient reference value is determined.
S3: constructing a reference value model of the water side pressure drop of the condenser and the evaporator;
s31: determining the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side according to the characteristic parameters obtained in the step S1;
specifically, according to the characteristic parameters obtained in the step S1, the qualitative temperature of the cooling water side is determined through the average water temperatures of the cooling water inlet and the cooling water outlet, the density, the dynamic viscosity coefficient, the kinematic viscosity coefficient, the heat conductivity coefficient and the constant pressure specific heat capacity of the cooling water at the qualitative temperature are determined through the qualitative temperature of the cooling water side, the flow velocity in the condenser pipe is determined through the inner diameter of the condenser pipe and the flow rate of the cooling water, the reynolds number is determined through the flow velocity in the condenser pipe, the inner diameter of the condenser pipe and the kinematic viscosity coefficient of the cooling water, the prandtl number is determined through the dynamic viscosity coefficient of the cooling water, the constant pressure specific heat capacity of the cooling water and the heat conductivity coefficient of the cooling water, and the convection heat transfer coefficient of the cooling water side is determined through the prandtl number, the reynolds number, the inner diameter of the condenser pipe and the heat conductivity coefficient of the cooling water;
wherein, the concrete formula is as follows:
v c ＝4m c /πD ic 2 (9)
R ec ＝v c D ic /ν c (10)
P rc ＝μ cc c pc /λ c (11)
α lc D ic /λ c ＝0.023R ec 0.8 P rc a (12)
wherein m is c For cooling water flow, kg/s, D ic Is the inner diameter of the condenser tube and has the unit of m, v c Is the flow velocity in the condenser tube, and has the unit of m/s, v c Is the coefficient of kinematic viscosity of cooling water, and has the unit of m 2 /s，λ c The coefficient of thermal conductivity of the cooling water at a certain temperature is represented by W/(m x K), R ec Is the Reynolds number, P, of the water in the condenser tube rc The Prandtl number of water in the condenser tube is 0.4 in the case of cooling water, and 0.3, mu in the case of chilled water cc Is the dynamic viscosity coefficient of water in the condenser tube at a qualitative temperature, and has a unit of Pa s, c pc Is the constant pressure specific heat capacity of cooling water at a qualitative temperature, alpha lc The heat transfer coefficient of convection on the cooling water side is W/(m) 2 *K)。
Determining the qualitative temperature of a freezing water side through the average water temperature of a freezing water inlet and an average water temperature of a freezing water outlet, determining the density, the dynamic viscosity coefficient, the kinematic viscosity coefficient, the heat conductivity coefficient and the constant pressure specific heat capacity of the freezing water at the qualitative temperature through the qualitative temperature of the freezing water side, determining the flow velocity in an evaporator tube through the inner diameter of the evaporator tube and the flow of the freezing water, determining the Reynolds number through the flow velocity in the evaporator tube, the inner diameter of the evaporator tube and the kinematic viscosity coefficient of the freezing water, determining the Prandtl number through the dynamic viscosity coefficient of the freezing water, the constant pressure specific heat capacity of the freezing water and the heat conductivity coefficient of the freezing water, and determining the convection heat transfer coefficient of the freezing water side through the Prandtl number, the Reynolds number, the inner diameter of the evaporator tube and the heat conductivity coefficient of the freezing water;
wherein, the concrete formula is as follows:
v e ＝4m l /πD ie 2 (13)
R ee ＝v e D ie /ν e (14)
P re ＝μ ce c pe /λ e (15)
α le D ie /λ e ＝0.023R ee 0.8 P re a (16)
wherein m is l Is the flow rate of the chilled water, kg/s, D ie Is the inner diameter of the evaporator tube, and has the unit of m, v e Is the flow velocity in the evaporator tube, and has the unit of m/s, v e Is the kinematic viscosity coefficient of the frozen water and has the unit of m 2 /s，λ e The coefficient of thermal conductivity of the frozen water at a qualitative temperature is represented by W/(m × K), R ee Is the Reynolds number, P, of the water in the evaporator tubes re The Prandtl number of water in the evaporator tube is 0.4 in the case of cooling water, and 0.3, mu in the case of chilled water ce Is the dynamic viscosity coefficient of water in the evaporator tube at a qualitative temperature, and has a unit of Pa s, c pe Is the specific heat capacity at constant pressure of the frozen water at a qualitative temperature, alpha le The unit is W/(m) for the convection heat transfer coefficient of the chilled water side 2 *K)。
S32: determining the wall temperature of the condenser and the wall temperature of the evaporator according to the characteristic parameters, the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side obtained in the step S1;
specifically, according to the characteristic parameters obtained in the step S1, the wall temperature of the condenser is determined by the heat absorption capacity of the condenser, the heat exchange area of the condenser, the convection heat exchange coefficient of the chilled water side, the fouling thermal resistance of the condenser, the inner diameter of the condenser pipe, the outer diameter of the condenser pipe, the wall thickness of the condenser pipe, the heat conduction coefficient of the condenser pipe, the temperature of the cooling water inlet, and the temperature of the cooling water outlet, and the wall temperature of the evaporator is determined by the heat absorption capacity of the evaporator, the heat exchange area of the evaporator, the convection heat transfer coefficient of the chilled water side, the fouling thermal resistance of the evaporator, the inner diameter of the evaporator pipe, the outer diameter of the evaporator pipe, the wall thickness of the evaporator pipe, the heat conduction coefficient of the evaporator pipe, the temperature of the chilled water inlet, and the temperature of the chilled water outlet;
specifically, the formula is as follows:
q c ＝10 3 Q c /F c (17)
q c ＝ΔT ic /((1/α lc +R fc )D Oc /D ic +δ c D Oc /λ cc D mc +R fc ) (18)
ΔT ic ＝((T co -T wc )-(T wc -T ci ))/ln((T co -T wc )-(T wc -T ci )) (19)
wherein, F c Represents the heat exchange area of the condenser and has a unit of m 2 ，q c Denotes the heat flow density of the condenser in W/m 2 ，ΔT ic Represents the logarithmic mean temperature difference between the inlet and outlet temperature of the cooling water and the temperature of the outer wall of the pipe, and has the unit of K, alpha lc Represents the convective heat transfer coefficient on the cooling water side, W/(m) 2 ·K)，R fc Denotes fouling resistance of condenser, m 2 ·K/W，D oc Represents the outside diameter of the condenser tube in m, delta c Is the wall thickness of the condenser tube, and has a unit of m, lambda cc The heat conductivity coefficient of the condenser pipe is W/(m × K), D mc Represents the average of the condenser tube inner diameter and the condenser tube outer diameter in m, T wc Represents the wall temperature of the condenser, K.
q e ＝10 3 Q e /F e (20)
q e ＝ΔT ie /((1/α le +R fe )D Oe /D ie +δ e D Oe /λ ce D me +R fe ) (21)
ΔT ie ＝((T eo -T we )-(T we -T ei ))/ln((T eo -T we )-(T we -T ei )) (22)
Wherein, F e Denotes the heat exchange area of the evaporator in m 2 ，q e Denotes the heat flow density of the evaporator in W/m 2 ，ΔT ie Represents the logarithmic mean temperature difference between the inlet and outlet temperature of the chilled water and the temperature of the outer wall of the pipe, and the unit is K, alpha le Represents the convective heat transfer coefficient on the chilled water side, W/(m) 2 ·K)，R fe Denotes fouling resistance of evaporator, m 2 ·K/W，D oe Denotes the outer diameter of the evaporator tube in m, delta e Is the thickness of the tube wall of the evaporator, and has the unit of m, lambda ce The heat conductivity coefficient of the condenser pipe is W/(m x K), D me The average value of the inner diameter of the evaporator tube and the outer diameter of the evaporator tube is expressed in m, T we Represents the wall temperature of the evaporator, K.
Specifically, the fouling thermal resistance of the condenser refers to the sum of the fouling thermal resistance in the condenser tube and the fouling thermal resistance outside the condenser tube, and the fouling thermal resistance of the evaporator refers to the sum of the fouling thermal resistance in the evaporator tube and the fouling thermal resistance outside the evaporator tube.
S33: determining the cooling water side pressure drop of the condenser and the cooling water side pressure drop of the evaporator according to the characteristic parameters, the condenser tube wall temperature and the evaporator tube wall temperature obtained in the step S1;
specifically, according to the characteristic parameters obtained in the step S1, the mass flow rate in the cooling water pipe is determined through the pipe inner diameter of the condenser and the cooling water flow; determining the pressure drop of the condenser tube side through the mass flow rate in the cooling water tube, the fluid density of the cooling water at the qualitative temperature in the tube, the length of the condenser tube, the number of the condenser tube side, the inner diameter of the condenser tube, the friction coefficient in the condenser tube and the wall temperature correction coefficient of the condenser tube side; determining the return bending pressure drop of the condenser according to the mass flow rate in the cooling water pipe, the cooling water density at the qualitative temperature in the pipe, the pipe length of the condenser and the pipe pass number of the condenser; determining the mass flow rate in the cooling water inlet and outlet pipe nozzles through the cooling water flow and the diameter of the inlet and outlet pipe nozzles of the condenser pipe pass; determining the pressure drop of the inlet and outlet nozzles of the condenser according to the mass flow rate of the cooling water in the inlet and outlet nozzles and the cooling water density at the qualitative temperature in the pipe; determining the pressure drop of the cooling water side of the condenser through the condenser tube side pressure drop, the condenser return bend pressure drop, the condenser inlet and outlet nozzle pressure drop and the condenser tube side pressure drop correction coefficient;
specifically, the calculation process is as follows:
G ic ＝4m c /πD ic 2 (23)
ΔP ic ＝(G ic 2 /2ρ wc )(L c N tpc /D ic )(f ic /φ ic ) (24)
ΔP rc ＝(G ic 2 /2ρ wc )4L c N tpc (25)
G Nc ＝4m c /πD nc 2 (26)
ΔP Nc ＝1.5G Nc 2 /2ρ wc (27)
ΔP c ＝(ΔP ic +ΔP rc )F ic +ΔP Nc (28)
wherein, G ic The mass flow rate in the cooling water pipe is expressed in kg/(m) 2 ·s)，ρ wc Denotes the density of cooling water in kg/m at a qualitative temperature 3 ，L c Represents the condenser tube length in m, N tpc Denotes the number of condenser passes, f ic Represents the friction coefficient in the condenser tube, is related to the type of the tube, and has no dimension phi ic Represents the correction coefficient of the wall temperature of the tube side of the condenser, phi ic ＝(μ cc /μ ic ) 0.14 Dimensionless,. DELTA.P ic Represents the pressure drop of the condenser tube side, pa, mu cc Represents the dynamic viscosity coefficient, pa s, mu, of the cooling water at a certain temperature in the tube ic Represents the dynamic viscosity coefficient, pa · s, Δ P, of the cooling water at the tube wall temperature rc Shows the return pressure drop, pa, D, of the condenser nc The diameters m and G of the inlet and outlet nozzles of the condenser tube pass are shown Nc Represents the mass flow rate, Δ P, of cooling water in the inlet and outlet nozzles Nc Showing pressure drop of inlet and outlet, pa, Δ P c Denotes the condenser pressure drop, pa, F ic The condenser tube side pressure drop correction factor is shown.
Determining the mass flow rate in the chilled water pipe through the inner diameter of the pipe of the evaporator and the flow of the chilled water; determining the pressure drop of the evaporator tube pass through the mass flow rate in the freezing water tube, the freezing water density at the qualitative temperature in the tube, the length of the evaporator tube, the number of the evaporator tube passes, the inner diameter of the evaporator tube, the friction coefficient in the evaporator tube and the wall temperature correction coefficient of the evaporator tube pass; determining the back bending pressure drop of the evaporator according to the mass flow rate in the chilled water pipe, the cooling water density at the qualitative temperature in the pipe, the length of the evaporator pipe and the number of evaporator pipe passes; determining the mass flow rate of the chilled water in the inlet and outlet pipe nozzles through the chilled water flow and the diameter of the inlet and outlet pipe nozzles of the tube pass of the evaporator; determining the pressure drop of the inlet and outlet nozzles of the evaporator through the mass flow rate of the chilled water in the inlet and outlet nozzles and the chilled water density at the qualitative temperature in the pipe; determining the cooling water side pressure drop of the evaporator through the evaporator tube side pressure drop, the evaporator return pressure drop, the evaporator inlet and outlet nozzle pressure drop and the evaporator tube side pressure drop correction coefficient;
specifically, the calculation process is as follows:
G ie ＝4m l /πD ie 2 (29)
ΔP ie ＝(G ie 2 /2ρ we )(L e N tpe /D ie )(f ie /φ ie ) (30)
ΔP re ＝(G ie 2 /2ρ we )4L e N tpe (31)
G Ne ＝4m l /πD ne 2 (32)
ΔP Ne ＝1.5G Ne 2 /2ρ we (33)
ΔP e ＝(ΔP ie +ΔP re )F ie +ΔP Ne (34)
wherein, G ie The unit is kg/(m) and represents the mass flow rate in the freezing water pipe 2 ·s)，ρ we The density of the frozen water at a qualitative temperature is shown in kg/m 3 ，L e Denotes the evaporator tube length in m, N tpe Denotes the number of evaporator passes, f ie Expressing the friction coefficient in the evaporator tube, and is related to the type of the tube, dimensionless, phi ie Represents the correction coefficient of the tube side wall temperature of the evaporator, phi ie ＝(μ ce /μ ie ) 0.14 Dimensionless,. DELTA.P ie Shows the tube side pressure drop of the evaporator, pa, mu ce Represents the dynamic viscosity coefficient of the chilled water at a certain temperature in the pipe, pa · s, mu ie Expressing the dynamic viscosity coefficient, pa s, Δ P, of the chilled water at the tube wall temperature re Expressing the return pressure drop, pa, D, of the evaporator ne The diameters m and G of the inlet and outlet nozzles of the tube pass of the evaporator are shown Ne Indicating chilled waterMass flow rate, Δ P, in the inlet and outlet nozzles Ne Showing pressure drop of inlet and outlet, pa, Δ P e Indicating the evaporator pressure drop, pa, F ic The evaporator tube side pressure drop correction factor is shown.
S34: constructing a condenser water side pressure drop reference value model and an evaporator water side pressure drop reference value model according to the water side pressure drops of the condenser and the evaporator under normal working conditions,
specifically, the formula used is as follows:
ΔP c ＝f(T k ,T e ,f r ) (35)
ΔP e ＝f(T k ,T e ,f r ) (36)
wherein, T k And T e Respectively representing the condensation temperature of the condenser and the evaporation temperature of the evaporator, f r And a load rate representing the operation of the chiller.
Specifically, a mapping relation among the comprehensive heat transfer coefficient, the condensing temperature, the evaporating temperature and the load factor is established through a least square method, the least square model is trained through the running values of the characteristic parameters under 500 groups of normal working conditions, which are obtained through S1, the regression coefficient in the model is obtained, and the water side pressure drop reference value model is determined.
S4: obtaining and comparing the actual value and the reference value of the comprehensive heat transfer coefficient of the condenser and the evaporator to obtain the conclusion whether the heat transfer performance of the condenser and the evaporator is deteriorated;
specifically, the method comprises the following steps: step S4 specifically includes the following steps:
s41: when the water chilling unit runs, collecting the running values of the characteristic parameters collected in the step S1 in real time;
specifically, the characteristic parameters may be collected in multiple groups, which may be 10 groups.
S42: inputting the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41 into a reference value model of the comprehensive heat transfer coefficient of the condenser and the evaporator to obtain a reference value of the comprehensive heat transfer coefficient of the condenser and the evaporator;
s43: calculating an actual value of the comprehensive heat transfer coefficient of the condenser and the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
s431: determining the heat absorption capacity of the cooling water in the condenser and the heat release capacity of the freezing water in the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
specifically, according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41, the heat absorption capacity of the cooling water in the condenser is determined through the flow rate of the cooling water, the constant-pressure specific heat capacity of the cooling water at the qualitative temperature, the inlet water temperature of the cooling water and the outlet water temperature of the cooling water, and is specifically calculated through a formula (1); determining the heat release amount of the chilled water in the evaporator through the chilled water flow, the constant-pressure specific heat capacity of the chilled water at the qualitative temperature, the chilled water inlet water temperature and the chilled water outlet water temperature, and specifically calculating through a formula (3);
s432: determining the logarithmic mean temperature difference of the condenser and the logarithmic mean temperature difference of the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
specifically, according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41, the logarithmic mean temperature difference of the condenser is determined through the cooling water inlet water temperature, the cooling water outlet water temperature and the condensing temperature of the condenser, and is specifically calculated through a formula (2); determining the logarithmic mean temperature difference of the evaporator through the chilled water inlet water temperature, the chilled water outlet water temperature and the evaporation temperature of the evaporator, and specifically calculating through a formula (4);
s433: determining the integrated heat transfer coefficient KF of the condenser from the heat absorption amount of the cooling water determined in step S431 and the logarithmic mean temperature difference of the condenser determined in step S432 based on the conservation of energy c The integrated heat transfer coefficient value of the condenser is the integrated heat transfer coefficient actual value of the condenser, and the integrated heat transfer coefficient KF of the evaporator is determined by the heat release amount of the chilled water determined in step S431 and the logarithmic mean temperature difference of the evaporator determined in step S432 e The comprehensive heat transfer coefficient value of the evaporator is the actual value of the comprehensive heat transfer coefficient of the evaporator and is calculated by a formula (5) and a formula (6);
s44: judging whether the reference value of the comprehensive heat transfer coefficient of the condenser obtained in the step S42 is obviously larger than the actual value obtained in the step S43 or not based on a significance detection method in statistics, if so, obtaining the conclusion that the heat exchange performance of the condenser is degraded, otherwise, obtaining the conclusion that the heat exchange performance of the condenser is not degraded; and judging whether the reference value of the comprehensive heat transfer coefficient of the evaporator obtained in the step S42 is obviously larger than the actual value obtained in the step S43, if so, obtaining the conclusion that the heat exchange performance of the evaporator is degraded, otherwise, obtaining the conclusion that the heat exchange performance of the evaporator is not degraded.
Specifically, the fact that the reference value of the comprehensive heat transfer coefficient of the condenser is significantly larger than the actual value of the comprehensive heat transfer coefficient of the condenser means that a difference value 3 σ can be determined according to multiple judgments based on a statistical significance detection method 1 When the comprehensive heat transfer coefficient reference value of the condenser is +3 sigma 1 >When the comprehensive heat transfer coefficient actual value of the condenser is obtained, the comprehensive heat transfer coefficient reference value of the condenser is considered to be obviously larger than the comprehensive heat transfer coefficient actual value of the condenser; the reference value of the comprehensive heat transfer coefficient of the evaporator is obviously larger than the actual value of the comprehensive heat transfer coefficient of the evaporator, namely, based on the significance detection method in statistics, a difference value 3 sigma can be determined according to multiple judgments 2 When the integrated heat transfer coefficient of the evaporator is a reference value of +3 sigma 2 >And when the comprehensive heat transfer coefficient actual value of the evaporator is obtained, the comprehensive heat transfer coefficient reference value of the evaporator is considered to be obviously larger than the comprehensive heat transfer coefficient actual value of the evaporator.
S5: and obtaining and comparing the actual values of the water side pressure drops of the condenser and the evaporator with a reference value to obtain a conclusion whether the flow performances of the condenser and the evaporator are degraded or not.
Specifically, the method comprises the following steps: the step S5 specifically includes the following steps:
s51: when the water chilling unit operates, acquiring the operation value of the characteristic parameter acquired in the step S1 in real time;
specifically, the characteristic parameters may be collected in multiple groups, which may be 10 groups.
S52: inputting the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51 into a reference value model of the water side pressure drop of the condenser and the evaporator to obtain a reference value of the water side pressure drop of the condenser and the evaporator;
s53: calculating actual values of the water side pressure drops of the condenser and the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51;
s531: determining the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51;
specifically, according to the real-time characteristic parameters of the condenser and the evaporator obtained in step S51, the qualitative temperature of the cooling water side is determined through the average water temperatures of the inlet and the outlet of the cooling water, the density, the kinetic viscosity coefficient, the kinematic viscosity coefficient, the heat conductivity coefficient and the specific heat capacity at the constant pressure of the cooling water at the qualitative temperature are determined through the qualitative temperature of the cooling water side, the flow velocity in the condenser pipe is determined through the inner diameter of the condenser pipe and the flow rate of the cooling water, the reynolds number is determined through the flow velocity in the condenser pipe, the inner diameter of the condenser pipe and the kinematic viscosity coefficient of the cooling water, the prandtl number is determined through the kinetic viscosity coefficient, the specific heat capacity at the constant pressure of the cooling water and the heat conductivity coefficient of the cooling water, the convective heat transfer coefficient at the cooling water side is determined through the prandtl number, the reynolds number, the inner diameter of the condenser pipe and the heat conductivity coefficient of the cooling water, and specifically calculated through formula (9) -formula (12);
determining the qualitative temperature of the side of the chilled water according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51 and the average water temperature of the inlet and the outlet of the chilled water, determining the density, the dynamic viscosity coefficient, the kinematic viscosity coefficient, the heat conductivity coefficient and the specific heat capacity at the qualitative temperature of the side of the chilled water, determining the flow rate in the evaporator tube according to the inner diameter and the flow rate of the chilled water, determining the Reynolds number according to the flow rate in the evaporator tube, the inner diameter of the evaporator tube and the kinematic viscosity coefficient of the chilled water, determining the Prandtl number according to the dynamic viscosity coefficient, the specific heat capacity at the constant pressure of the chilled water and the heat conductivity coefficient of the chilled water, determining the convective heat transfer coefficient of the side of the chilled water according to the Prandtl number, the Reynolds number, the inner diameter of the evaporator tube and the heat conductivity coefficient of the chilled water, and specifically calculating by the formula (13) -formula (16);
s532: determining the wall temperature of the condenser and the wall temperature of the evaporator according to the real-time characteristic parameters of the condenser and the evaporator, the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side obtained in the step S51;
specifically, according to the real-time characteristic parameters of the condenser and the evaporator obtained in step S51, the wall temperature of the condenser is determined according to the heat absorption capacity of the condenser, the heat exchange area of the condenser, the convection heat exchange coefficient of the chilled water side, the fouling thermal resistance of the condenser, the inner diameter of the condenser tube, the outer diameter of the condenser tube, the wall thickness of the condenser tube, the heat conductivity coefficient of the condenser tube, the inlet temperature of the cooling water and the outlet temperature of the cooling water, and the wall temperature of the evaporator is determined according to the heat absorption capacity of the evaporator, the heat exchange area of the evaporator, the convection heat transfer coefficient of the chilled water side, the fouling thermal resistance of the evaporator, the inner diameter of the evaporator tube, the outer diameter of the evaporator tube, the wall thickness of the evaporator tube, the heat conductivity coefficient of the evaporator tube, the inlet temperature of the chilled water and the outlet temperature of the chilled water, and is specifically calculated according to formula (17) -formula (22);
s533: determining the cooling water side pressure drop of the condenser and the cooling water side pressure drop of the evaporator according to the real-time characteristic parameters of the condenser and the evaporator, the wall temperature of the condenser and the wall temperature of the evaporator obtained in the step S51, wherein the cooling water side pressure drop value of the condenser is the actual cooling water side pressure drop value of the condenser, the cooling water side pressure drop value of the evaporator is the actual cooling water side pressure drop value of the evaporator,
specifically, according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51, the mass flow rate in the cooling water pipe is determined through the pipe inner diameter of the condenser and the cooling water flow; determining the pressure drop of the condenser tube side through the mass flow rate in the cooling water tube, the fluid density of the cooling water at the qualitative temperature in the tube, the length of the condenser tube, the number of the condenser tube side, the inner diameter of the condenser tube, the friction coefficient in the condenser tube and the wall temperature correction coefficient of the condenser tube side; determining the return bending pressure drop of the condenser according to the mass flow rate in the cooling water pipe, the cooling water density at the qualitative temperature in the pipe, the pipe length of the condenser and the pipe pass number of the condenser; determining the mass flow rate in the cooling water inlet/outlet pipe nozzle through the cooling water flow and the diameter of the inlet/outlet pipe nozzle of the condenser pipe pass; determining the pressure drop of the inlet and outlet nozzles of the condenser according to the mass flow rate of the cooling water in the inlet and outlet nozzles and the cooling water density at the qualitative temperature in the pipe; determining the cooling water side pressure drop of the condenser through the condenser tube side pressure drop, the condenser return bend pressure drop, the condenser inlet and outlet nozzle pressure drop and the condenser tube side pressure drop correction coefficient, wherein the cooling water side pressure drop value of the condenser is the actual cooling water side pressure drop value of the condenser, and is specifically calculated through a formula (23) -a formula (28);
determining the mass flow rate in the chilled water pipe through the inner diameter of the pipe of the evaporator and the flow of the chilled water; determining the pressure drop of the evaporator tube pass through the mass flow rate in the freezing water tube, the freezing water density at the qualitative temperature in the tube, the length of the evaporator tube, the number of the evaporator tube passes, the inner diameter of the evaporator tube, the friction coefficient in the evaporator tube and the wall temperature correction coefficient of the evaporator tube pass; determining the back bending pressure drop of the evaporator according to the mass flow rate in the chilled water pipe, the cooling water density at the qualitative temperature in the pipe, the length of the evaporator pipe and the number of evaporator pipe passes; determining the mass flow rate of the chilled water in the inlet and outlet pipe nozzles through the chilled water flow and the diameter of the inlet and outlet pipe nozzles of the tube pass of the evaporator; determining the pressure drop of the inlet and outlet nozzles of the evaporator through the mass flow rate of the chilled water in the inlet and outlet nozzles and the chilled water density at the qualitative temperature in the pipe; determining the cooling water side pressure drop of the evaporator through the evaporator tube side pressure drop, the evaporator return pressure drop, the evaporator inlet and outlet mouth pressure drop and the evaporator tube side pressure drop correction coefficient, wherein the cooling water side pressure drop value of the evaporator is the actual cooling water side pressure drop value of the evaporator and is specifically calculated through a formula (29) -a formula (34);
s54: judging whether the reference value of the water side pressure drop of the condenser obtained in the step S52 is obviously larger than the actual value obtained in the step S53 or not based on a significance detection method in statistics, if so, obtaining the conclusion that the flow performance of the condenser is degraded, otherwise, obtaining the conclusion that the flow performance of the condenser is not degraded; and judging whether the reference value of the water side pressure drop of the evaporator obtained in the step S42 is obviously larger than the actual value obtained in the step S53, if so, obtaining the conclusion that the flow performance of the evaporator is degraded, otherwise, obtaining the conclusion that the flow performance of the evaporator is not degraded.
Specifically, the reference value of the pressure drop on the water side of the condenser is significantly larger than the actual value of the pressure drop on the water side of the condenser, which means that the reference value is based on the statisticsThe method can determine a difference 3 sigma according to multiple judgments 3 When the water side pressure drop reference value of the condenser is +3 sigma 3 >When the water side pressure drop actual value of the condenser is obtained, the water side pressure drop reference value of the condenser is considered to be obviously larger than the water side pressure drop actual value of the condenser; the reference value of the pressure drop on the water side of the evaporator is obviously larger than the actual value of the pressure drop on the water side of the evaporator, namely, based on a significance detection method in statistics, a difference value 3 sigma can be determined according to multiple judgments 4 When the water side pressure drop reference value of the evaporator is +3 sigma 4 >And when the water side pressure drop actual value of the evaporator is larger than the reference value, the water side pressure drop reference value of the evaporator is considered to be obviously larger than the water side pressure drop actual value of the evaporator.
The method for diagnosing the performance degradation of the compressor of the water chilling unit is specifically described by taking a 125-ton (about 440 kW) centrifugal water chilling unit as an object, wherein the water chilling unit comprises the compressor, a condenser, an evaporator and an electronic expansion valve, the compressor is a centrifugal compressor, the evaporator and the condenser are both shell-and-tube heat exchangers, water flows in a tube, a refrigerant flows out of the tube, and the refrigerant can be R134a.
S1: obtaining the operating values of a plurality of groups of characteristic parameters of a water chilling unit under normal working conditions, wherein the characteristic parameters mainly comprise: the heat exchanger comprises an evaporation pressure, a condensation pressure, a refrigerant outlet temperature of a condenser, a refrigerant inlet temperature of the condenser, a cooling water inlet water temperature, a cooling water outlet water temperature, a cooling water flow rate, a refrigerant outlet temperature of an evaporator, a refrigerant inlet temperature of an evaporator, a chilled water inlet water temperature, a chilled water outlet water temperature, a chilled water flow rate and structural parameters of the evaporator and the condenser, wherein the structural parameters of the evaporator and the condenser comprise a pipe inner diameter, a pipe outer diameter, a pipe inner dirt thermal resistance, a pipe outer dirt thermal resistance, a heat exchange area, a pipe wall thickness, a pipe heat conductivity coefficient, a pipe pass number and a pipe length. Specifically, 500 sets of characteristic parameters were collected at 10s intervals.
S2: establishing a reference value model of the comprehensive heat transfer coefficient of the condenser and the evaporator;
s21: according to the characteristic parameters obtained in the step S1, determining the heat absorption capacity of the cooling water in the condenser corresponding to 500 groups of characteristic parameters through the flow rate of the cooling water, the constant-pressure specific heat capacity of the cooling water at the qualitative temperature, the inlet water temperature of the cooling water and the outlet water temperature of the cooling water, and specifically calculating through a formula (1); determining logarithmic mean temperature difference of the condenser corresponding to 500 groups of characteristic parameters according to the water temperature of the cooling water inlet, the water temperature of the cooling water outlet and the condensation temperature of the condenser, and specifically calculating by a formula (2); determining the heat release of the chilled water in the evaporator corresponding to 500 groups of characteristic parameters through the chilled water flow, the constant-pressure specific heat capacity of the chilled water at the qualitative temperature, the chilled water inlet water temperature and the chilled water outlet water temperature, and specifically calculating through a formula (3); determining logarithmic mean temperature difference of the evaporators corresponding to 500 groups of characteristic parameters through chilled water inlet water temperature, chilled water outlet water temperature and evaporation temperature of the evaporators, and specifically calculating through a formula (4);
s22: based on energy conservation, determining the comprehensive heat transfer coefficient KF of the condenser corresponding to the 500 groups of characteristic parameters through the heat absorption quantity of the cooling water in the condenser determined in the step S21 and the logarithmic mean temperature difference of the condenser c Specifically, calculated by formula (5); determining the comprehensive heat transfer coefficient KF of the evaporator corresponding to 500 groups of characteristic parameters according to the heat release quantity of the frozen water in the evaporator and the logarithmic mean temperature difference of the evaporator determined in the step S21 e Specifically, the calculation is carried out by formula (6);
s23: after the characteristic parameters of the water chilling unit under the normal working condition are obtained, a comprehensive heat transfer coefficient reference value model of the condenser is constructed according to the comprehensive heat transfer coefficients of the condenser corresponding to the multiple groups of characteristic parameters and a formula (7), a comprehensive heat transfer coefficient reference value model of the evaporator is constructed according to the comprehensive heat transfer coefficients of the evaporator corresponding to the multiple groups of characteristic parameters and a formula (8), and partial results are presented in table 1;
in the embodiment, a mapping relation between the comprehensive heat transfer coefficient and the condensing temperature, the evaporating temperature and the load factor is established by a least square method, specifically, a least square model is trained through the running values of 500 groups of characteristic parameters under normal working conditions, which are obtained in S1, so as to obtain a regression coefficient in the model, and determine a comprehensive heat transfer coefficient reference value model;
s3: constructing a reference value model of the water side pressure drop of the condenser and the evaporator;
s31: determining a qualitative temperature of a cooling water side through average water temperatures of a cooling water inlet and a cooling water outlet according to the characteristic parameters obtained in the step S1, determining the density, the dynamic viscosity coefficient, the kinematic viscosity coefficient, the heat conductivity coefficient and the specific heat capacity of the cooling water at the qualitative temperature through the qualitative temperature of the cooling water side, determining the flow rate in the condenser pipe through the inner diameter of the condenser pipe and the flow rate of the cooling water, determining the Reynolds number through the flow rate in the condenser pipe, the inner diameter of the condenser pipe and the kinematic viscosity coefficient of the cooling water, determining the Prandtl number through the dynamic viscosity coefficient of the cooling water, the specific heat capacity of the cooling water at the constant pressure and the heat conductivity coefficient of the cooling water, determining the convection heat exchange coefficient of the cooling water side corresponding to 500 sets of characteristic parameters through the Prandol number, the Reynolds number, the inner diameter of the condenser pipe and the heat conductivity coefficient of the cooling water, and specifically calculating through a formula (9) -a formula (12);
determining the qualitative temperature of a freezing water side through the average water temperature of a freezing water inlet and an average water temperature of a freezing water outlet, determining the density, the dynamic viscosity coefficient, the kinematic viscosity coefficient, the heat conductivity coefficient and the constant pressure specific heat capacity of the freezing water at the qualitative temperature through the qualitative temperature of the freezing water side, determining the flow rate in an evaporator tube through the inner diameter of the evaporator tube and the flow rate of the freezing water, determining the Reynolds number through the flow rate in the evaporator tube, the inner diameter of the evaporator tube and the kinematic viscosity coefficient of the freezing water, determining the Prandtl number through the dynamic viscosity coefficient of the freezing water, the constant pressure specific heat capacity of the freezing water and the heat conductivity coefficient of the freezing water, determining the convection heat transfer coefficient of the freezing water side corresponding to 500 sets of characteristic parameters through the Prandtl number, the Reynolds number, the inner diameter of the evaporator tube and the heat conductivity coefficient of the freezing water, and specifically calculating through a formula (13) -a formula (16);
s32: according to the characteristic parameters obtained in the step S1, determining the wall temperature of the condenser corresponding to 500 groups of characteristic parameters through the heat absorption capacity of the condenser, the heat exchange area of the condenser, the convection heat exchange coefficient of the chilled water side, the dirt thermal resistance of the condenser, the inner diameter of the condenser pipe, the outer diameter of the condenser pipe, the wall thickness of the condenser pipe, the heat conduction coefficient of the condenser pipe, the inlet temperature of cooling water and the outlet temperature of the cooling water, and specifically calculating through a formula (17) -a formula (19); the method comprises the following steps of determining the evaporator tube wall temperature corresponding to 500 sets of characteristic parameters through the heat absorption capacity of an evaporator, the heat exchange area of the evaporator, the convection heat transfer coefficient of a chilled water side, the fouling resistance of the evaporator, the inner diameter of an evaporator tube, the outer diameter of the evaporator tube, the wall thickness of the evaporator tube, the heat conductivity coefficient of the evaporator tube, the inlet temperature of chilled water and the outlet temperature of chilled water, and specifically calculating through a formula (20) -a formula (22);
s33: determining the mass flow rate in the cooling water pipe according to the characteristic parameters obtained in the step S1 and through the inner diameter of the pipe of the condenser and the flow rate of the cooling water; determining the pressure drop of the condenser tube side through the mass flow rate in the cooling water tube, the fluid density of the cooling water at the qualitative temperature in the tube, the length of the condenser tube, the number of the condenser tube side, the inner diameter of the condenser tube, the friction coefficient in the condenser tube and the wall temperature correction coefficient of the condenser tube side; determining the return bending pressure drop of the condenser according to the mass flow rate in the cooling water pipe, the cooling water density at the qualitative temperature in the pipe, the pipe length of the condenser and the pipe pass number of the condenser; determining the mass flow rate in the cooling water inlet/outlet pipe nozzle through the cooling water flow and the diameter of the inlet/outlet pipe nozzle of the condenser pipe pass; determining the pressure drop of the inlet and outlet nozzles of the condenser according to the mass flow rate of the cooling water in the inlet and outlet nozzles and the cooling water density at the qualitative temperature in the pipe; determining the cooling water side pressure drop of the condenser corresponding to 500 groups of characteristic parameters through the condenser tube side pressure drop, the condenser return pressure drop, the condenser inlet and outlet nozzle pressure drop and the condenser tube side pressure drop correction coefficient, and specifically calculating through a formula (23) -a formula (28);
determining the mass flow rate in the chilled water pipe through the inner diameter of the pipe of the evaporator and the flow of the chilled water; determining the pressure drop of the evaporator tube pass through the mass flow rate in the freezing water tube, the freezing water density at the qualitative temperature in the tube, the length of the evaporator tube, the number of the evaporator tube passes, the inner diameter of the evaporator tube, the friction coefficient in the evaporator tube and the wall temperature correction coefficient of the evaporator tube pass; determining the back bending pressure drop of the evaporator according to the mass flow rate in the chilled water pipe, the cooling water density at the qualitative temperature in the pipe, the length of the evaporator pipe and the number of evaporator pipe passes; determining the mass flow rate of the chilled water in the inlet and outlet pipe nozzles through the chilled water flow and the diameter of the inlet and outlet pipe nozzles of the tube pass of the evaporator; determining the pressure drop of an inlet/outlet nozzle of the evaporator through the mass flow rate of the chilled water in the inlet/outlet nozzle and the chilled water density at the qualitative temperature in the pipe; determining cooling water side pressure drop of the evaporator corresponding to 500 groups of characteristic parameters through the evaporator tube side pressure drop, the evaporator return pressure drop, the evaporator inlet and outlet mouth pressure drop and the evaporator tube side pressure drop correction coefficient, and specifically calculating through a formula (29) -a formula (34);
s34: after the characteristic parameters of the water chilling unit under the normal working condition are obtained, a condenser water side pressure drop reference value model is constructed according to the condenser water side pressure drops corresponding to the characteristic parameters and a formula (35), an evaporator water side pressure drop reference value model is constructed according to the evaporator water side pressure drops corresponding to the characteristic parameters and a formula (36), and partial results are presented in a table 2;
in the embodiment, a mapping relation between water side pressure drop and condensing temperature, evaporating temperature and load factor is established by a least square method, specifically, a least square model is trained through operation values of 500 groups of characteristic parameters under normal working conditions, which are obtained in S1, so as to obtain a regression coefficient in the model, and determine a water side pressure drop reference value model;
s4: obtaining and comparing the actual value and the reference value of the comprehensive heat transfer coefficient of the condenser and the evaporator to obtain the conclusion whether the heat transfer performance of the condenser and the evaporator is deteriorated;
specifically, the method comprises the following steps: step S4 specifically includes the following steps:
s41: and when the water chilling unit runs, collecting the running values of the characteristic parameters collected in the step S1 in real time, wherein the characteristic parameters can be collected into a plurality of groups, and 10 groups can be collected.
S42: inputting the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41 into a reference value model of the comprehensive heat transfer coefficient of the condenser and the evaporator to obtain a reference value of the comprehensive heat transfer coefficient of the condenser and the evaporator;
s43: calculating an actual value of the comprehensive heat transfer coefficient of the condenser and the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
s431: according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41, determining the heat absorption capacity of the cooling water in the condenser through the flow rate of the cooling water, the constant-pressure specific heat capacity of the cooling water at the qualitative temperature, the inlet water temperature of the cooling water and the outlet water temperature of the cooling water, and specifically calculating through a formula (1); determining the heat release amount of the chilled water in the evaporator through the chilled water flow, the constant-pressure specific heat capacity of the chilled water at the qualitative temperature, the chilled water inlet water temperature and the chilled water outlet water temperature, and specifically calculating through a formula (3);
s432: according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41, determining the logarithmic mean temperature difference of the condenser through the water temperature of the cooling water inlet, the water temperature of the cooling water outlet and the condensation temperature of the condenser, and specifically calculating through a formula (2); determining the logarithmic mean temperature difference of the evaporator through the chilled water inlet water temperature, the chilled water outlet water temperature and the evaporation temperature of the evaporator, and specifically calculating through a formula (4);
s433: determining the comprehensive heat transfer coefficient KF of the condenser from the heat absorption amount of the cooling water determined in step S431 and the logarithmic mean temperature difference of the condenser determined in step S432 c The integrated heat transfer coefficient value of the condenser is the integrated heat transfer coefficient actual value of the condenser, and the integrated heat transfer coefficient KF of the evaporator is determined by the heat release amount of the chilled water determined in step S431 and the logarithmic mean temperature difference of the evaporator determined in step S432 e The comprehensive heat transfer coefficient value of the evaporator is the actual comprehensive heat transfer coefficient value of the evaporator, and is calculated by a formula (5) and a formula (6), wherein partial results are shown in a table 1;
s44: judging whether the reference value of the comprehensive heat transfer coefficient of the condenser obtained in the step S42 is obviously larger than the actual value obtained in the step S43 or not based on a significance detection method in statistics, if so, obtaining the conclusion that the heat exchange performance of the condenser is degraded, otherwise, obtaining the conclusion that the heat exchange performance of the condenser is not degraded; and judging whether the reference value of the comprehensive heat transfer coefficient of the evaporator obtained in the step S42 is significantly larger than the actual value obtained in the step S43, if so, obtaining a conclusion that the heat exchange performance of the evaporator is degraded, otherwise, obtaining a conclusion that the heat exchange performance of the evaporator is not degraded, wherein partial results are shown in Table 3.
S5: and obtaining and comparing the actual values of the water side pressure drops of the condenser and the evaporator with a reference value to obtain a conclusion whether the flow performances of the condenser and the evaporator are degraded or not.
Specifically, the method comprises the following steps: the step S5 specifically includes the following steps:
s51: and when the water chilling unit runs, collecting the running values of the characteristic parameters collected in the step S1 in real time, wherein the characteristic parameters can be collected into a plurality of groups, and 10 groups can be collected.
S52: inputting the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51 into a reference value model of the water side pressure drop of the condenser and the evaporator to obtain a reference value of the water side pressure drop of the condenser and the evaporator;
s53: calculating actual values of the water side pressure drops of the condenser and the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51;
s531: determining the qualitative temperature of the cooling water side according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51 and the average water temperature of the inlet and the outlet of the cooling water, determining the density, the kinetic viscosity coefficient, the kinematic viscosity coefficient, the heat conductivity coefficient and the constant-pressure specific heat capacity of the cooling water at the qualitative temperature of the cooling water side, determining the flow speed in the condenser pipe according to the inner diameter of the condenser pipe and the flow rate of the cooling water, determining the Reynolds number according to the flow speed in the condenser pipe, the inner diameter of the condenser pipe and the kinematic viscosity coefficient of the cooling water, determining the Prandtl number according to the kinetic viscosity coefficient of the cooling water, the constant-pressure specific heat capacity of the cooling water and the heat conductivity coefficient of the cooling water, determining the convection heat transfer coefficient of the cooling water side according to the Prandtl number, the Reynolds number, the inner diameter of the condenser pipe and the heat conductivity coefficient of the cooling water, and specifically calculating the formula (9) -formula (12);
determining the qualitative temperature of the side of the chilled water according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51 and the average water temperature of the inlet and the outlet of the chilled water, determining the density, the dynamic viscosity coefficient, the kinematic viscosity coefficient, the heat conductivity coefficient and the specific heat capacity at the qualitative temperature of the side of the chilled water, determining the flow rate in the evaporator tube according to the inner diameter and the flow rate of the chilled water, determining the Reynolds number according to the flow rate in the evaporator tube, the inner diameter of the evaporator tube and the kinematic viscosity coefficient of the chilled water, determining the Prandtl number according to the dynamic viscosity coefficient, the specific heat capacity at the constant pressure of the chilled water and the heat conductivity coefficient of the chilled water, determining the convective heat transfer coefficient of the side of the chilled water according to the Prandtl number, the Reynolds number, the inner diameter of the evaporator tube and the heat conductivity coefficient of the chilled water, and specifically calculating by the formula (13) -formula (16);
s532: determining the wall temperature of the condenser through the heat absorption capacity of the condenser, the heat exchange area of the condenser, the convection heat exchange coefficient of a chilled water side, the fouling thermal resistance of the condenser, the inner diameter of the condenser pipe, the outer diameter of the condenser pipe, the wall thickness of the condenser pipe, the heat conduction coefficient of the condenser pipe, the inlet temperature of cooling water and the outlet temperature of the cooling water according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51, determining the wall temperature of the evaporator through the heat absorption capacity of the evaporator, the heat exchange area of the evaporator, the convection heat transfer coefficient of the chilled water side, the fouling thermal resistance of the evaporator, the inner diameter of the evaporator pipe, the outer diameter of the evaporator pipe, the wall thickness of the evaporator pipe, the heat conduction coefficient of the evaporator pipe, the inlet temperature of the chilled water and the outlet temperature of the chilled water, and specifically calculating through a formula (17) -a formula (22);
s533: determining the mass flow rate in the cooling water pipe according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51 and through the inner diameter of the pipe of the condenser and the flow rate of the cooling water; determining the pressure drop of the condenser tube side through the mass flow rate in the cooling water tube, the fluid density of the cooling water at the qualitative temperature in the tube, the length of the condenser tube, the number of the condenser tube side, the inner diameter of the condenser tube, the friction coefficient in the condenser tube and the wall temperature correction coefficient of the condenser tube side; determining the return bending pressure drop of the condenser according to the mass flow rate in the cooling water pipe, the cooling water density at the qualitative temperature in the pipe, the pipe length of the condenser and the pipe pass number of the condenser; determining the mass flow rate in the cooling water inlet and outlet pipe nozzles through the cooling water flow and the diameter of the inlet and outlet pipe nozzles of the condenser pipe pass; determining the pressure drop of the inlet and outlet nozzles of the condenser according to the mass flow rate of the cooling water in the inlet and outlet nozzles and the density of the cooling water at the qualitative temperature in the pipe; determining the cooling water side pressure drop of the condenser through the condenser tube side pressure drop, the condenser return bend pressure drop, the condenser inlet and outlet nozzle pressure drop and the condenser tube side pressure drop correction coefficient, wherein the cooling water side pressure drop value of the condenser is the actual cooling water side pressure drop value of the condenser, and is specifically calculated through a formula (23) -a formula (28), and partial results are presented in a table 2;
determining the mass flow rate in the chilled water pipe through the inner diameter of the pipe of the evaporator and the flow of the chilled water; determining the pressure drop of the evaporator tube pass through the mass flow rate in the freezing water tube, the freezing water density at the qualitative temperature in the tube, the length of the evaporator tube, the number of the evaporator tube passes, the inner diameter of the evaporator tube, the friction coefficient in the evaporator tube and the wall temperature correction coefficient of the evaporator tube pass; determining the back bending pressure drop of the evaporator through the mass flow rate in the chilled water pipe, the cooling water density under the qualitative temperature in the pipe, the length of the evaporator pipe and the number of evaporator pipe passes; determining the mass flow rate of the chilled water in the inlet and outlet pipe nozzles through the chilled water flow and the diameter of the inlet and outlet pipe nozzles of the tube pass of the evaporator; determining the pressure drop of the inlet and outlet nozzles of the evaporator through the mass flow rate of the chilled water in the inlet and outlet nozzles and the chilled water density at the qualitative temperature in the pipe; determining the cooling water side pressure drop of the evaporator through the evaporator tube side pressure drop, the evaporator return pressure drop, the evaporator inlet and outlet mouth pressure drop and the evaporator tube side pressure drop correction coefficient, wherein the cooling water side pressure drop value of the evaporator is the actual cooling water side pressure drop value of the evaporator, and is specifically calculated through a formula (29) to a formula (34), and partial results are presented in table 2;
s54: judging whether the reference value of the water side pressure drop of the condenser obtained in the step S52 is obviously larger than the actual value obtained in the step S53 or not based on a significance detection method in statistics, if so, obtaining the conclusion that the flow performance of the condenser is degraded, otherwise, obtaining the conclusion that the flow performance of the condenser is not degraded; it is determined whether the reference value of the water side pressure drop of the evaporator obtained in step S42 is significantly larger than the actual value obtained in step S43, and if so, it is concluded that the flow performance of the evaporator is deteriorated, otherwise, it is concluded that the flow performance of the evaporator is not deteriorated, wherein some of the results are presented in table 4.
Tables 3 and 4 show that: the method for diagnosing the performance degradation of the condenser and the evaporator of the water chilling unit can effectively diagnose the performance degradation of the condenser and the evaporator of the water chilling unit in real time; the method for diagnosing the performance degradation of the condenser and the evaporator of the water chilling unit reduces the complexity of the construction of the comprehensive heat transfer coefficient and the water side pressure drop reference model of the condenser and the evaporator, is simple to calculate and has lower implementation cost; inefficient operation and impaired operation of the condenser and evaporator can be effectively avoided.
TABLE 1
Figure GDA0003833584690000241
TABLE 2
Figure GDA0003833584690000242
Figure GDA0003833584690000251
TABLE 3
Figure GDA0003833584690000252
TABLE 4
Figure GDA0003833584690000253
In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they 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.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims (10)

1. A method for diagnosing performance degradation of a condenser and an evaporator of a water chilling unit is characterized by comprising the following steps:
s1: acquiring the operating values of a plurality of groups of characteristic parameters of a water chilling unit under normal working conditions;
s2: establishing a reference value model of the comprehensive heat transfer coefficient of the condenser and the evaporator;
s3: constructing a reference value model of the water side pressure drop of the condenser and the evaporator;
s4: obtaining and comparing the actual value and the reference value of the comprehensive heat transfer coefficient of the condenser and the evaporator to obtain the conclusion whether the heat transfer performance of the condenser and the evaporator is deteriorated;
s5: obtaining and comparing the actual values of the pressure drop of the water sides of the condenser and the evaporator with a reference value to obtain a conclusion whether the flow performance of the condenser and the evaporator is deteriorated;
in the step S3, the cooling water side pressure drop of the condenser and the cooling water side pressure drop of the evaporator are determined according to the characteristic parameters collected in the step S1; according to the water side pressure drop of the condenser and the evaporator under the normal working condition, a mapping relation between the water side pressure drop and the condensing temperature, the evaporating temperature and the load factor is established, the model is trained through the operation value of the characteristic parameters under the normal working condition obtained in the S1, the regression coefficient in the model is obtained, and a condenser water side pressure drop reference value model and an evaporator water side pressure drop reference value model are established.
2. The method for diagnosing degradation of condenser and evaporator performance of a chiller according to claim 1, wherein the step S2 specifically includes:
s21: determining the heat absorption capacity of cooling water in the condenser, the logarithmic mean temperature difference of the condenser, the heat release capacity of frozen water in the evaporator and the logarithmic mean temperature difference of the evaporator according to the characteristic parameters obtained in the step S1;
s22: determining the comprehensive heat transfer coefficient KF of the condenser from the heat absorption amount of the cooling water in the condenser and the logarithmic mean temperature difference of the condenser determined in step S21 c Determining the comprehensive heat transfer coefficient KF of the evaporator by the heat release of the freezing water in the evaporator and the logarithmic mean temperature difference of the evaporator determined in the step S21 e ；
S23: constructing a comprehensive heat transfer coefficient reference value model of the condenser and a comprehensive heat transfer coefficient reference value model of the evaporator according to the comprehensive heat transfer coefficients of the condenser and the evaporator corresponding to the multiple groups of characteristic parameters, wherein the adopted formulas are as follows:
KF c ＝f(T k ,T e ,f r )
KF e ＝f(T k ,T e ,f r )
wherein, T k And T e Respectively representing the condensation and evaporation temperatures, f r And a load rate representing the operation of the chiller.
3. The method for diagnosing performance degradation of the condenser and the evaporator of the water chilling unit according to claim 2, wherein in the step S23, a mapping relation between the comprehensive heat transfer coefficient and the condensing temperature, the evaporating temperature and the load factor is established by a method based on least square, and a least square model is trained by the operation value of the characteristic parameter under the normal working condition obtained in the step S1 to obtain a regression coefficient in the model, so as to determine a comprehensive heat transfer coefficient reference value model.
4. The method for diagnosing deterioration of condenser and evaporator performance of a water chilling unit according to claim 1, wherein the step S3 specifically includes:
s31: determining a convective heat transfer coefficient on the cooling water side and a convective heat transfer coefficient on the freezing water side according to the characteristic parameters obtained in the step S1;
s32: determining the wall temperature of the condenser and the wall temperature of the evaporator according to the characteristic parameters, the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side obtained in the step S1;
s33: determining the cooling water side pressure drop of the condenser and the cooling water side pressure drop of the evaporator according to the characteristic parameters, the condenser tube wall temperature and the evaporator tube wall temperature obtained in the step S1;
s34: according to the water side pressure drop of the condenser and the evaporator under the normal working condition, a condenser water side pressure drop reference value model and an evaporator water side pressure drop reference value model are constructed, and the adopted formulas are as follows:
ΔP c ＝f(T k ,T e ,f r )
ΔP e ＝f(T k ,T e ,f r )
wherein, T k And T e Respectively representing the condensation temperature and the evaporation temperature, f r And a load rate representing the operation of the chiller.
5. The method for diagnosing performance degradation of the condenser and the evaporator of the water chilling unit according to claim 4, wherein in the step S34, a mapping relation between the water side pressure drop and the condensing temperature, the evaporating temperature and the load factor is constructed based on a least square method, and a least square model is trained through the operation value of the characteristic parameter under the normal working condition obtained in the step S1, so as to obtain a regression coefficient in the model and determine a water side pressure drop reference value model.
6. The method for diagnosing deterioration of condenser and evaporator performance of a water chilling unit according to claim 1, wherein the step S4 specifically includes:
s41: when the water chilling unit runs, collecting the running values of the characteristic parameters collected in the step S1 in real time;
s42: inputting the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41 into a reference value model of the comprehensive heat transfer coefficient of the condenser and the evaporator to obtain a reference value of the comprehensive heat transfer coefficient of the condenser and the evaporator;
s43: calculating an actual value of the comprehensive heat transfer coefficient of the condenser and the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
s44: judging whether the reference value of the comprehensive heat transfer coefficient of the condenser obtained in the step S42 is obviously larger than the actual value obtained in the step S43 or not based on a significance detection method in statistics, if so, obtaining the conclusion that the heat exchange performance of the condenser is degraded, otherwise, obtaining the conclusion that the heat exchange performance of the condenser is not degraded; and judging whether the reference value of the comprehensive heat transfer coefficient of the evaporator obtained in the step S42 is significantly larger than the actual value obtained in the step S43, if so, obtaining a conclusion that the heat exchange performance of the evaporator is degraded, otherwise, obtaining a conclusion that the heat exchange performance of the evaporator is not degraded.
7. The method for diagnosing degradation of condenser and evaporator performance of a chiller according to claim 6, wherein the step S43 specifically includes:
s431: determining the heat absorption capacity of the cooling water in the condenser and the heat release capacity of the frozen water in the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
s432: determining the logarithmic mean temperature difference of the condenser and the logarithmic mean temperature difference of the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S41;
s433: determining the integrated heat transfer coefficient KF of the condenser from the heat absorption amount of the cooling water determined in step S431 and the logarithmic mean temperature difference of the condenser determined in step S432 based on the conservation of energy c The integrated heat transfer coefficient value of the condenser is the integrated heat transfer coefficient actual value of the condenser, and the integrated heat transfer coefficient KF of the evaporator is determined by the heat release amount of the chilled water determined in step S431 and the logarithmic mean temperature difference of the evaporator determined in step S432 e And the comprehensive heat transfer coefficient value of the evaporator is the actual comprehensive heat transfer coefficient value of the evaporator.
8. The method for diagnosing deterioration of condenser and evaporator performance of a water chilling unit according to claim 1, wherein the step S5 specifically includes:
s51: when the water chilling unit operates, acquiring the operation value of the characteristic parameter acquired in the step S1 in real time;
s52: inputting the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51 into a reference value model of the water side pressure drop of the condenser and the evaporator to obtain a reference value of the water side pressure drop of the condenser and the evaporator;
s53: calculating actual values of the water side pressure drops of the condenser and the evaporator according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51;
s54: judging whether the reference value of the water side pressure drop of the condenser obtained in the step S52 is obviously larger than the actual value obtained in the step S53 or not based on a significance detection method in statistics, if so, obtaining the conclusion that the flow performance of the condenser is degraded, otherwise, obtaining the conclusion that the flow performance of the condenser is not degraded; and judging whether the reference value of the water side pressure drop of the evaporator obtained in the step S42 is obviously larger than the actual value obtained in the step S53, if so, obtaining the conclusion that the flow performance of the evaporator is degraded, otherwise, obtaining the conclusion that the flow performance of the evaporator is not degraded.
9. The method for diagnosing deterioration of condenser and evaporator performance of a water chilling unit according to claim 8, wherein in step S53:
s531: determining the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side according to the real-time characteristic parameters of the condenser and the evaporator obtained in the step S51;
s532: determining the wall temperature of the condenser and the wall temperature of the evaporator according to the real-time characteristic parameters of the condenser and the evaporator, the convective heat transfer coefficient of the cooling water side and the convective heat transfer coefficient of the freezing water side obtained in the step S51;
s533: and determining the cooling water side pressure drop of the condenser and the cooling water side pressure drop of the evaporator according to the real-time characteristic parameters of the condenser and the evaporator, the wall temperature of the condenser and the wall temperature of the evaporator, which are obtained in the step S51, wherein the cooling water side pressure drop value of the condenser is the actual cooling water side pressure drop value of the condenser, and the cooling water side pressure drop value of the evaporator is the actual cooling water side pressure drop value of the evaporator.
10. The method for diagnosing the performance degradation of the condenser and the evaporator of the water chilling unit according to claim 1, wherein the characteristic parameters in the step S1 include a cooling water flow rate, a cooling water inlet water temperature, a cooling water outlet water temperature, a condensation temperature of the condenser, a chilled water flow rate, a chilled water inlet water temperature, a chilled water outlet water temperature, an evaporation temperature of the evaporator, an evaporation pressure, a condensation pressure, and structural parameters of the evaporator and the condenser, wherein the structural parameters of the evaporator and the condenser include a heat exchange area, a fouling thermal resistance, a pipe inner diameter, a pipe outer diameter, a pipe wall thickness, a pipe thermal conductivity, a pipe pass number and a pipe length.
CN202110535668.6A 2021-05-17 2021-05-17 Performance degradation diagnosis method for condenser and evaporator of water chilling unit Active CN113281074B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110535668.6A CN113281074B (en) 2021-05-17 2021-05-17 Performance degradation diagnosis method for condenser and evaporator of water chilling unit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110535668.6A CN113281074B (en) 2021-05-17 2021-05-17 Performance degradation diagnosis method for condenser and evaporator of water chilling unit

Publications (2)

Publication Number Publication Date
CN113281074A CN113281074A (en) 2021-08-20
CN113281074B true CN113281074B (en) 2023-01-13

Family

ID=77279455

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110535668.6A Active CN113281074B (en) 2021-05-17 2021-05-17 Performance degradation diagnosis method for condenser and evaporator of water chilling unit

Country Status (1)

Country Link
CN (1) CN113281074B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116029134B (en) * 2023-01-09 2023-11-28 华能苏州热电有限责任公司 Method for establishing heat transfer model of condenser under different operation conditions
CN116105392B (en) * 2023-04-12 2023-07-14 广东美的暖通设备有限公司 Control method and device for centrifugal water chilling unit

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107192571A (en) * 2017-06-15 2017-09-22 西安交通大学 Horizontal tube bundle and the outer refrigeration working medium falling film evaporation of single tube, pool boiling and condensation phase change heat exchange test device
CN107844799A (en) * 2017-10-17 2018-03-27 西安建筑科技大学 A kind of handpiece Water Chilling Units method for diagnosing faults of integrated SVM mechanism
CN109000949A (en) * 2018-06-29 2018-12-14 广州能迪能源科技股份有限公司 Water cooler appraisal procedure and power-economizing method based on water cooler thermodynamical model
CN110046662A (en) * 2019-04-10 2019-07-23 河南科技大学 Water cooler combined failure diagnostic method and system based on model and data fusion
CN111623570A (en) * 2020-06-09 2020-09-04 常州工学院 Water chilling unit energy efficiency diagnosis method and system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107192571A (en) * 2017-06-15 2017-09-22 西安交通大学 Horizontal tube bundle and the outer refrigeration working medium falling film evaporation of single tube, pool boiling and condensation phase change heat exchange test device
CN107844799A (en) * 2017-10-17 2018-03-27 西安建筑科技大学 A kind of handpiece Water Chilling Units method for diagnosing faults of integrated SVM mechanism
CN109000949A (en) * 2018-06-29 2018-12-14 广州能迪能源科技股份有限公司 Water cooler appraisal procedure and power-economizing method based on water cooler thermodynamical model
CN110046662A (en) * 2019-04-10 2019-07-23 河南科技大学 Water cooler combined failure diagnostic method and system based on model and data fusion
CN111623570A (en) * 2020-06-09 2020-09-04 常州工学院 Water chilling unit energy efficiency diagnosis method and system

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
基于参数集总模型的冷水机组结垢故障检测与诊断研究;鹿琳;《中国优秀硕士学位论文全文数据库 工程科技II辑》;20190531;正文第23-24页 *
热泵机组能效性能劣化诊断研究;王占伟;《中国优秀硕士学位论文全文数据库 工程科技II辑》;20150831;正文第18，29-36,42,47-48,53页 *

Also Published As

Publication number Publication date
CN113281074A (en) 2021-08-20

Similar Documents

Publication Publication Date Title
CN113281074B (en) Performance degradation diagnosis method for condenser and evaporator of water chilling unit
CN106524410B (en) A kind of diagnostic method of central air-conditioning water cooler actual efficiency
CN213178638U (en) Waste heat recovery type air conditioning system
CN108731190B (en) Detection method, detection device and detection system for air conditioner host parameters
CN101048627A (en) Method for estimating inlet and outlet air conditions of an HVAC system
CN102353403B (en) Methods for measuring chilled water flow and cooling medium flow of central air-conditioning host machine
CN111623570A (en) Water chilling unit energy efficiency diagnosis method and system
CN111706958A (en) Central air conditioning fault performance detection system based on big data processing
CN109000949A (en) Water cooler appraisal procedure and power-economizing method based on water cooler thermodynamical model
CN110046662B (en) Water chilling unit composite fault diagnosis method and system based on model and data fusion
CN115654796A (en) Oil return control method and device and multi-split system
CN113569497B (en) Soft measurement method for condenser cooling water flow
CN214701170U (en) Combined type air-conditioning box anti-freezing device
CN113310173B (en) Control system and control method of air cooling unit
JP6595139B1 (en) Air conditioning management system, air conditioning management method, and program
JP2018204920A (en) Performance diagnostic device and performance diagnostic method for absorption type refrigerator
CN210014575U (en) Refrigerating system
CN113613459A (en) Cooling system, electronic equipment and control method thereof
CN218916005U (en) Heat exchanger and air conditioning unit
CN217876218U (en) Air conditioner compressor protection device
CN212205029U (en) Condenser assembly and air conditioner
CN217357647U (en) Condensing unit and condensing machine
CN216525658U (en) Flue gas condensation water trap
JP3083930B2 (en) Failure diagnosis system for absorption refrigerator
CN203533842U (en) Air conditioner condensed water comprehensive utilization device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant