JP6988366B2 - Performance deterioration diagnostic method and diagnostic equipment for water-cooled turbo chillers - Google Patents

Description

The present invention relates to a method or an apparatus for diagnosing deterioration of refrigerator performance due to contamination of cooling water in a water-cooled turbo chiller.

In a turbo chiller, a compressor, a condenser, and an evaporator are connected to each other by piping to form a refrigeration cycle.

There are two types of turbo chillers: air-cooled and water-cooled. Above all, in the water-cooled turbo chiller, the cooling water circulates with the outdoor cooling tower. There are open type and closed type cooling towers, but in the case of open type cooling towers, the cooling water comes into contact with the outside air and becomes dirty, and the heat transfer surface of the heat exchanger (condenser) inside the refrigerator gets dirty. Therefore, the heat exchange performance deteriorates. As the heat exchange performance deteriorates, the amount of electric power required to produce cold water with the same amount of water and the same temperature in the refrigerator increases. Therefore, it is important to evaluate the performance deterioration due to the cooling water contamination and control the amount of chemicals added to prevent the contamination from adhering to the heat transfer surface.

Conventionally, a simple method of measuring and recording the difference between the refrigerant condensation temperature and the cooling water condenser outlet temperature (LTD = Leaving Temple Difference) and evaluating the refrigerator performance by LTD has often been adopted. ..

Until now, the cooling water circulating between the refrigerator and the cooling tower has often been at a constant flow rate. However, in order to save energy, there are an increasing number of cases where the amount of cooling water is controlled by an inverter according to the cooling load. In such a case, the LTD will fluctuate regardless of the state of contamination of the heat transfer surface. It is not appropriate to use it as a performance control index for refrigerators. Further, even if the dirt condition of the heat transfer surface is the same, the LTD value changes depending on the magnitude of the cooling load, so it is necessary to take measures such as extracting only the data at the same cooling load and managing the performance.

For example, Patent Document 1 discloses an "absorption chiller-heater cooling water stain diagnosis system". This calculates the normalized logarithmic mean temperature difference (= logarithmic mean temperature at diagnosis / logarithmic mean temperature difference at normal time) in each of the condenser and the absorber, and determines the cooling water contamination based on the calculated logarithmic mean temperature difference. It is a cooling water stain diagnosis system.

Further, Patent Document 2 discloses a "deterioration diagnosis system for heat source equipment". Patent Document 2 describes the diagnosis result and the performance deterioration of the heat source machine by performing the diagnosis using the "contamination coefficient in the condenser tube" and the "heat transfer coefficient in the condenser tube" whose relationship with the performance deterioration of the heat source machine is clear. It is disclosed that the performance recovery effect at the time of cleaning the heat transfer tube can be easily and accurately predicted.

Japanese Unexamined Patent Publication No. 7-151416 Japanese Unexamined Patent Publication No. 2005-345406

However, Patent Documents 1 and 2 still have a common problem that "the influence of cooling water contamination on the operating cost of the refrigerator is unknown".

In Patent Document 1, the demerit caused by dirt is not quantified, and when the "normalized logarithmic mean temperature difference" reaches what value, it is judged that "countermeasures are necessary", and how much it should be lowered to "abnormal". It is unclear whether it can be judged that it is not.

Further, in Patent Document 2, it is unclear what value the "condensation coefficient in the condenser tube" and the "heat transfer coefficient in the condenser tube" should reach to determine that "countermeasures are necessary". In addition, it is difficult to quantitatively show the cost-effectiveness of the performance recovery effect when cleaning the heat transfer tube.

For example, it is not wasteful to set an upper limit value for the stain coefficient and use it as a control index, but it is insufficient as a basis for taking measures such as chemical addition and cleaning. As a basis for taking measures, it is desirable to quantitatively show the cost merit.

The present invention has been made in view of such a problem, and the problem is that in a water-cooled turbo-type refrigerator, the degree of heat transfer surface contamination is quantitatively shown, and the cost reduction effect by measures such as addition of chemicals can be achieved. It is to provide a diagnostic method and a diagnostic apparatus which can be obtained.

In order to achieve the above-mentioned problems, the present inventors analyzed the operation data around the refrigerator and repeated diligent research. As a result, the coefficient of performance (COP) of the water-cooled turbo chiller was cooled. By obtaining the finding that the logarithmic mean temperature difference between water and cold water has a high correlation, it was found that the above-mentioned problems can be solved, and the present invention has been completed. Specifically, the present invention provides the following.

(1) The present invention is a method for diagnosing performance deterioration of a water-cooled turbo refrigerator, which is based on a step of calculating an actual operating COP and an operating logarithmic mean temperature difference during operation of the refrigerator, and cooling water contamination. The above is the case where the value of the logarithmic mean temperature difference is the value of the logarithmic mean temperature difference during operation by using the correlation formula showing the relationship between the COP and the logarithmic mean temperature difference in the normal state where there is no deterioration in the performance of the refrigerator. From the step of calculating the normal COP when the water-cooled turbo refrigerator is in the normal state and the ratio of the operating COP to the normal COP, the degree of heat transfer surface contamination in the condenser inside the refrigerator It is a method of diagnosing performance deterioration of a water-cooled turbo refrigerator, including a step of diagnosing.

(2) Further, the present invention is the performance deterioration diagnosis method according to (1), wherein the step of diagnosing the degree of heat transfer surface contamination further performs the diagnosis based on the amount of increase in electric power in the refrigerator.

(3) Further, in the present invention, the step of diagnosing the degree of heat transfer surface contamination is based on the ratio of the COP during operation and the COP during normal operation and / or the tendency of the power increase amount in the refrigerator to change with time. This is the performance deterioration diagnosis method according to (1) or (2).

(4) Further, the present invention is a step of issuing an alarm when the ratio of the operating COP to the normal COP is not within the preset range and / or when the power increase amount becomes equal to or more than the preset value. The performance deterioration diagnostic method according to any one of (1) to (3), further comprising.

(5) Further, the present invention is a performance deterioration diagnostic device for diagnosing a performance deterioration of a water-cooled turbo refrigerator, and calculates an actual operating COP and an operating logarithmic mean temperature difference during operation of the refrigerator. The value of the logarithmic mean temperature difference is the logarithmic mean temperature of the operation using the operating parameter calculation means and the correlation formula showing the relationship between the COP and the logarithmic mean temperature difference in the normal state where there is no deterioration of the refrigerator performance due to contamination of the cooling water. The ratio of the normal COP and the normal COP to the normal COP calculation means for calculating the normal COP when the water-cooled turbo refrigerator is in the normal state when it is the value of the average temperature difference. Therefore, it is a performance deterioration diagnostic apparatus provided with a diagnostic means for diagnosing the degree of heat transfer surface contamination.

(6) Further, the present invention is the performance deterioration diagnostic apparatus according to (5), wherein the diagnostic means diagnoses the degree of heat transfer surface contamination based on the amount of increase in electric power in the refrigerator.

(7) Further, the present invention further includes a recording means for recording the ratio of the operating COP to the normal COP and / or the change over time in the amount of increase in power in the refrigerator, and the diagnostic means is the recording. The performance deterioration diagnostic apparatus according to (5) or (6), which diagnoses the degree of heat transfer surface contamination based on the results recorded in the means.

(8) Further, the present invention is an alarm that emits an alarm when the ratio of the operating COP to the normal COP is not within the preset range and / or when the power increase amount becomes equal to or more than the preset value. The performance deterioration diagnostic apparatus according to any one of (5) to (7), further comprising means.

According to the present invention, the logarithmic mean temperature difference between cooling water and cold water is used to calculate the normal COP in the normal state where there is no deterioration in the performance of the refrigerator due to contamination of the cooling water, and during actual operation of the refrigerator. From the ratio of the COP to the normal COP obtained by calculation, the degree of heat transfer surface contamination in the condenser inside the water-cooled turbo chiller is diagnosed. As a result, the degree of heat transfer surface contamination can be diagnosed more accurately than in the case of diagnosing the degree of heat transfer surface contamination from the difference (LTD) between the refrigerant condensation temperature and the condenser outlet temperature of the cooling water, and as a result, chemicals are added. It is possible to reduce the cost of maintaining the performance of the refrigerator by cleaning and cleaning.

The ratio of the COP during operation to the COP during normal operation has a smaller fluctuation range than the LTD, which is susceptible to fluctuations in the amount of cooling water and the cooling load, and the transition of the degree of contamination of the heat transfer surface can be grasped more accurately. , Suitable as a parameter for diagnosing the performance of the refrigerator. In addition, the COP is highly related to the amount of power used in the heat exchanger, and the ratio of the COP during operation to the COP during normal operation makes it possible to easily calculate the power consumption or the cost increase. .. Therefore, from the viewpoint of reducing the performance maintenance cost of the refrigerator due to the addition of chemicals and cleaning, it is preferable to adopt the ratio of the COP during operation to the COP during normal operation.

FIG. 1 is a schematic diagram showing a schematic configuration of a refrigeration system including the performance deterioration diagnosis device 1 according to the present embodiment. FIG. 2 is a schematic diagram showing a detailed configuration of the performance deterioration diagnosis device 1 according to the present embodiment. FIG. 3 is a diagram for explaining that the correlation between the COP and the logarithmic mean temperature difference in a normal state without deterioration of the refrigerator performance due to cooling water contamination is approximated by a linear function. FIG. 4 is an example of a trend graph in which the horizontal axis is the time axis and the vertical axis is the normalized COP. FIG. 5 is an example of a trend graph in which the horizontal axis is the time axis and the vertical axis is the amount of power increase.

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and the present invention is carried out with appropriate modifications within the scope of the object of the present invention. can do.

<Outline configuration of freezing system>
FIG. 1 is a schematic diagram showing a schematic configuration of a refrigeration system including the performance deterioration diagnosis device 1 according to the present embodiment. The refrigeration system includes a performance deterioration diagnosis device 1 and a water-cooled turbo chiller 5, and the performance deterioration diagnosis device 1 and the water-cooled turbo chiller 5 are connected via a communication network 6.

[Rough configuration of performance degradation diagnostic device 1]
The performance deterioration diagnosis device 1 inputs to the measurement value input unit 10 for inputting the measured value in the water-cooled turbo refrigerating machine 5 sent from the water-cooled turbo refrigerating machine 5 via the communication network 6 and the measurement value input unit 10. The data processing unit 20 that processes the data that has been processed and the data written in the database 40, the display unit 30 that displays the result processed by the data processing unit 20, and the database 40 that records the measurement data and the processed data thereof. Have.

The measurement value input unit 10 and the data processing unit 20 are configured to include a control device such as a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). The data processing unit 20 executes a predetermined program stored in itself to perform arithmetic processing on the data sent from the measured value input unit 10 and the data written in the database 40. The program is composed of a correlation expression creation module, an operating parameter calculation module, a normal COP calculation module, a diagnostic module, a power increase calculation module, a recording module, an alarm module, and the like.

The correlation equation creation module is a module for creating a correlation equation showing the relationship between the COP and the logarithmic mean temperature difference in a normal state without deterioration of the refrigerator performance due to cooling water contamination.

The operating parameter calculation module is a module for calculating the actual operating COP and the operating logarithmic mean temperature difference during the operation of the refrigerator.

The normal COP calculation module uses a correlation equation showing the relationship between the COP in the normal state and the logarithmic mean temperature difference without deterioration of the refrigerator performance due to cooling water contamination, and the value of the logarithmic mean temperature difference is the logarithmic mean during operation. It is a module for calculating the normal COP when the water-cooled turbo chiller 5 is in the normal state when it is the value of the temperature difference.

The diagnostic module is a module for diagnosing the degree of heat transfer surface contamination of the water-cooled centrifugal chiller 5 from the ratio of the operating COP and the normal COP.

The power increase calculation module is a module for calculating the power increase due to cooling water contamination.

The recording module is a module for recording the ratio of the operating COP to the normal COP and / or the change over time in the amount of increase in electric power in the water-cooled centrifugal chiller 5.

The alarm module sends an alarm to the display unit 30 when the ratio between the operating COP and the normal COP becomes less than or equal to the preset value and / or when the power increase amount becomes equal to or more than the preset value. It is a module to execute the process to make it.

The display unit 30 is not particularly limited as long as it can notify the administrator who manages the state of the water-cooled turbo chiller 5 of the diagnosis result of the deterioration of the refrigerator performance due to the contamination of the cooling water.

The database 40 is a device for storing data and files, and includes a data storage unit such as a hard disk, a semiconductor memory, a recording medium, and a memory card.

The database 40 stores the above-mentioned operating parameter calculation module, normal COP calculation module, diagnostic module, power increase calculation module, recording module, program for executing the alarm module, and the like. ..

[Rough configuration of turbo refrigerator 5]
The turbo refrigerator 5 includes a compressor, a condenser, and an evaporator.

[Compressor]
The compressor has a function of increasing the pressure of the refrigerant gas. The high-pressure refrigerant gas whose pressure has been increased by the compressor is pushed into the condenser.

[Condenser]
The condenser is a heat exchanger for cooling water and refrigerant gas. The refrigerant gas pushed into the condenser is indirectly cooled by the cooling water. When the refrigerant gas is cooled and falls below the boiling point, the state of the refrigerant changes from gas to liquid. Then, the refrigerant as a liquid is sent to the evaporator.

On the other hand, the temperature of the cooling water passing through the condenser rises by removing heat from the refrigerant gas.

In the case of a water-cooled turbo chiller, a cooling tower is installed in a place different from the refrigerator, and the cooling tower is used to lower the temperature of the cooling water, and again as cooling water for condensing the refrigerant gas in the condenser. Use. As a result, the cold water production capacity of the refrigerator can be maintained.

Since the cooling tower is installed outdoors, in the case of an open cooling tower, the cooling water circulating between the cooling tower and the refrigerator gets dirty in contact with the outside air in the process of passing through the cooling tower, and becomes dirty on the cooling water side of the condenser. Since dirt adheres to the heat transfer surface of the flow path, the heat exchange performance deteriorates. This embodiment is a technique for more accurately diagnosing the degree of contamination of the heat transfer surface, and as a result, reducing the performance maintenance cost of the refrigerator by adding chemicals or cleaning to prevent the adhesion of stains to the heat transfer surface. Is to provide.

[Evaporator]
The evaporator is a heat exchanger of water and refrigerant. The water passing through the evaporator transfers heat to the liquid refrigerant supplied to the evaporator. At that time, the refrigerant evaporates and undergoes a phase transition from a liquid to a gas (refrigerant gas). The phase-shifted refrigerant gas is supplied to the compressor again.

On the other hand, the water passing through the evaporator is deprived of heat corresponding to the latent heat of vaporization of the refrigerant, the temperature is lowered, and the water is supplied to the outside of the refrigerator as cold water. The cold water supplied from the refrigerator is used as a cooling heat source for cooling purposes such as air conditioning, and the water whose temperature has risen again after use is returned to the evaporator through the cold water pipe.

As described above, it is possible to release the heat taken by the evaporator with the condenser by repeating the phase transition of the refrigerant from gas to liquid and from liquid to gas. By enabling the periodic change of the refrigerant in this way, a refrigeration cycle can be realized.

[Data collection unit 51]
Further, the turbo type refrigerator 5 includes a data acquisition unit 51 necessary for its control. The data collection unit 51 includes a cooling water inlet temperature (T _wi ) from the cooling tower to the condenser, a cooling water outlet temperature (T _wo ) from the condenser to the cooling tower, and a chilled water inlet temperature (T wo) from the air conditioner or the like to the evaporator. T _ci ), the cold water outlet temperature from the evaporator to the air conditioner (T _co ), the flow rate of the cold water supplied from the air conditioner to the evaporator (F), and the power consumption for driving the turbo refrigerating machine 5 (T co). Measure the value of W). Then, the measured value is sent to the diagnostic apparatus via the communication network 6 and recorded in the database 40 at regular intervals.

The frequency of data recording may be appropriately adjusted according to the accuracy of diagnosis of performance deterioration and the processing load on the measuring instrument input unit 10. For example, the database 40 records measurement data every 1 minute. As a result, 60 points of data required for arithmetic processing in the data processing unit 20 can be obtained per hour.

<Detailed configuration of performance degradation diagnostic device 1>
FIG. 2 is a schematic diagram showing a detailed configuration of the performance deterioration diagnosis device 1.

[Measured value input unit 10]
The measurement data collected by the data collection unit 51 of the turbo refrigerator 5 is input to the measurement value input unit 10 via the communication network 6. The measured value input unit 10 records the input data in the database 40.

[Data processing unit 20]
The data processing unit 20 executes the following processing.

[Creating a correlation formula]
The data processing unit 20 executes the correlation equation creation module and creates a correlation equation showing the relationship between the COP and the logarithmic mean temperature difference in a normal state where there is no deterioration in the refrigerator performance due to cooling water contamination.

First, the data processing unit 20 obtains the COP and the logarithmic mean temperature difference from the input data to the measured value input unit 10 in a normal state in which the refrigerator performance is not deteriorated due to the contamination of the cooling water.

The COP is obtained by the following formula.
COP = cooling heat / power consumption (W)
Here, the amount of cooling heat = the flow rate of cold water (F) × the specific heat of cold water × (cold water inlet temperature (T _ci ) -cold water outlet temperature (T _co )).

The logarithmic mean temperature difference is obtained by the following equation.
Logarithmic mean temperature difference = (Δt _{1 − Δt 2} ) / ln (Δt ₁ / Δt ₂ )
Here, Δt ₁ = cooling water outlet temperature (T _wo ) -cold water inlet temperature (T _ci ).
Δt ₂ = cooling water inlet temperature (T _wi ) -cold water outlet temperature (T _co ).

Subsequently, the data processing unit 20 obtains a correlation equation when the horizontal axis is the logarithmic mean temperature difference and the vertical axis is the COP.

For example, if the database 40 records data every minute, 60 points of combination data of COP and logarithmic mean temperature difference can be obtained per hour. From the operation data for about 1 to 4 weeks, the relationship between the COP and the logarithmic mean temperature difference in the normal state where there is no deterioration in the refrigerator performance due to the cooling water contamination can be expressed by a correlation formula.

For simplicity, the correlation equation is preferably a linear function or an exponential function approximation.

In the above, it was explained that the correlation formula is obtained from the operation data based on the measured values, but if the correlation formula can be obtained from the data described in the catalog, specifications, etc. of the refrigerator manufacturer, it is described in the catalog, specifications, etc. The correlation formula may be obtained from the data of.

The obtained correlation equation is recorded on the hard disk of the computer that processes the data.

[Calculation of operating parameters]
Subsequently, the data processing unit 20 executes an operating parameter calculation module to calculate an actual operating COP and an operating logarithmic mean temperature difference during operation of the refrigerator.

The operating COP and the operating logarithmic mean temperature difference are obtained by the same equations used in the above [Creation of correlation equation].

For example, if the database 40 records data every minute, 60 points of combination data of the operating COP and the operating logarithmic mean temperature difference can be obtained.

[Calculation of COP at normal time]
Subsequently, the data processing unit 20 executes the normal COP calculation module, and uses the above correlation equation to use the water-cooled turbo chiller in the case where the value of the logarithmic mean temperature difference is the value of the logarithmic mean temperature difference during operation. The normal COP is calculated when 5 is a normal state (an ideal state assuming that there is no deterioration in the performance of the refrigerator due to contamination with cooling water).

[Diagnosis of degree of heat transfer surface stain]
Subsequently, the data processing unit 20 executes a diagnostic module and diagnoses the degree of heat transfer surface contamination of the water-cooled turbo chiller 5 from the ratio of the operating COP to the normal COP.

If the database 40 records data every minute, 60 points of combinations of operating COP and normal COP can be obtained per hour. For each of these combinations, the data processing unit 20 calculates the ratio of the operating COP to the normal COP (operating COP / normal COP, hereinafter also referred to as “normalized COP”).

If there is no deterioration in the refrigerator performance due to the cooling water contamination, the value of the normalized COP is 1, and as the cooling water contamination reduces the refrigerator performance, the value of the normalized COP decreases. Therefore, in the present embodiment, the normalized COP is utilized as one of the performance management indexes of the turbo type refrigerator 5, and when the normalized COP becomes equal to or less than a preset value, the refrigerator performance deteriorates due to cooling water contamination. Is supposed to be diagnosed as progressing.

In the present embodiment, when the normalized COP, that is, the operating COP / normal COP becomes equal to or less than a preset value, it is diagnosed that the refrigerator performance is deteriorated due to the cooling water contamination, but the present invention is limited to this. It's not a thing. When the normal COP / operating COP, which is the reciprocal of the normalized COP, becomes equal to or higher than a preset value, it may be diagnosed that the refrigerator performance is deteriorated due to the cooling water contamination.

[Calculation of power increase due to cooling water contamination]
Subsequently, the data processing unit 20 executes the power increase amount calculation module to calculate the power increase amount due to the cooling water contamination.

The amount of power increase is obtained by the following equation.
Power increase = Power consumption (W) for driving the turbo refrigerator 5-Cooling heat / Normal COP
Here, the amount of cooling heat = the flow rate of cold water (F) × the specific heat of cold water × (cold water inlet temperature (T _ci ) -cold water outlet temperature (T _co )).
The normal COP is a value created in the above [calculation of normal COP].

Alternatively, the amount of power increase can also be obtained by the following equation.
Power increase = Cooling heat x (1 / COP-1 during operation / COP during normal operation))

[Recording of normalized COP and / or power increase over time]
Subsequently, the data processing unit 20 executes the recording module and records the change over time in the amount of power increase in the normalized COP and / or the water-cooled turbo chiller 5.

If the database 40 records data every minute, 60 points of normalized COP can be obtained per hour. Therefore, the data processing unit 20 reads the measurement data at each time from the database 40, calculates the normalized COP, and records the calculation result in the database 40.

Similarly, the data processing unit 20 reads the measurement data at each time from the database 40, calculates the amount of power increase, and records the calculation result in the database 40.

[Alarm transmission]
Subsequently, the data processing unit 20 executes the alarm module, and for the display unit 30, the horizontal axis is the time axis, the vertical axis is the normalized COP, and the trend graph (time series display) and / or the horizontal axis is the time axis. , A trend graph with power consumption on the vertical axis is displayed together with the evaluation message.

If there is no deterioration in the refrigerator performance due to the cooling water contamination, the value of the normalized COP is 1, and as the cooling water contamination reduces the refrigerator performance, the value of the normalized COP decreases. Therefore, in the present embodiment, the normalized COP is utilized as one of the performance management indexes of the turbo type refrigerator 5, and when the normalized COP becomes equal to or less than a preset value, an alarm is transmitted on the display unit 30. It is supposed to be.

Similarly, when the amount of chemicals added to the cooling water passing through the inside of the condenser is insufficient or inappropriate, the amount of electric power used in the water-cooled turbo chiller 5 tends to increase. Therefore, in the present embodiment, the amount of increase in electric power is utilized as one of the performance management indexes of the turbo-type refrigerator 5, and when the amount of increase in electric power exceeds a preset value, an alarm is transmitted on the display unit 30. It is supposed to be.

[Display unit 30]
The display unit 30 is a trend graph (time) in which the horizontal axis is the time axis and the vertical axis is the normalized COP for the manager who manages the state of the water-cooled turbo chiller 5 according to the processing result of the data processing unit 20. It is possible to display a trend graph (time series display) in which the horizontal axis is the time axis and the vertical axis is the power consumption (series display) together with the evaluation message.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Using the performance deterioration diagnostic device 1 described in the present embodiment, various data were acquired in a normal state in which the refrigerator performance was not deteriorated due to cooling water contamination. Various data include the cooling water inlet temperature _{from the cooling tower to the condenser (T wi} ), the cooling water outlet temperature from the condenser to the cooling tower (T _wo ), and the chilled water inlet temperature from the air conditioner to the evaporator (T _ci). ), The cold water outlet temperature from the evaporator to the air conditioner (T _co ), the flow rate of the cold water supplied from the air conditioner to the evaporator (F), and the power consumption for driving the turbo type refrigerator 5 (W). including. The frequency of acquisition of various data was set to every 1 minute.

Then, using the acquired data, a correlation equation showing the relationship between the COP and the logarithmic mean temperature difference was created by linear function approximation. The results are shown in FIG.

As a result, a correlation equation of y = −0.1813x + 10.072 was obtained. Note that x is a logarithmic mean temperature difference (unit: ° C.), and y is a normal COP (unit: dimensionless). Further, the coefficient of determination R ² was 0.9475, and it was confirmed that the correlation equation was excellent in accuracy.

Subsequently, various data of the turbo type refrigerator 5 were acquired for half a year from April to September using the performance deterioration diagnosis device 1. The types and acquisition frequencies of various data are the same as the acquisition conditions under normal conditions where there is no deterioration in refrigerator performance due to cooling water contamination.

Then, using the various acquired data, the actual operating COP and the operating logarithmic mean temperature difference during the operation of the turbo type refrigerator 5 were calculated.

Further, the water-cooled turbo chiller 5 is in a normal state when the value of the logarithmic mean temperature difference is the value of the logarithmic mean temperature difference during operation using the above correlation formula: y = −0.1813x + 10.072. The normal COP of the case was calculated. For example, if the logarithmic mean temperature difference between cold water and cooling water is 20 ° C. at a certain time, y (normal COP) = 6.45 can be obtained by substituting 20 for x in the above correlation equation.

Then, for each combination of the operating COP and the normal COP, the ratio of the operating COP to the normal COP (normalized COP) was calculated. For example, as described above, assuming that the normal COP is 6.45 and the actual operating COP during operation of the turbo refrigerator 5 is 6.0, the normalized COP is 6.0 / 6. .45 = 0.93.

Then, a trend graph (time series display) in which the horizontal axis is the time axis and the vertical axis is the normalized COP is displayed on the display unit 30. The results are shown in FIG.

In the example of FIG. 4, even when the cooling load fluctuates, the value of the normalized COP is within the range of 0.98 to 1.02 (generally within the range of plus or minus 2%), and the cooling water is contaminated. There is little deterioration in the performance of the refrigerator due to this, and it can be judged that it is not necessary to add chemicals or wash the inside of the cooling water pipe provided in the condenser.

Further, the amount of increase in electric power due to the contamination of the cooling water was calculated, and a trend graph (time series display) in which the horizontal axis was the time axis and the vertical axis was the amount of electric power increase was displayed on the display unit 30. The results are shown in FIG.

Even if the temporal transition of "dirt coefficient" and "heat transfer coefficient" is displayed as a graph as in the conventional method, it was difficult to directly grasp how much it affects the operating cost. .. As shown in FIG. 5, by displaying a graph of the time transition of the amount of increase in electric power, it is possible to rationally proceed with the implementation of measures such as reviewing the cleaning frequency.

1 Performance degradation diagnostic device 10 Measurement value input unit 20 Data processing unit 30 Display unit 40 Database 5 Turbo-type refrigerator 51 Data collection unit 6 Communication network

Claims (8)

A condenser, which is a heat exchanger for cooling water and refrigerant,
It is a heat exchanger for water and refrigerant, and is a method for diagnosing performance deterioration of a water-cooled turbo chiller including an evaporator that supplies cold water to the outside.
The step of calculating the actual operating COP and the operating logarithmic mean temperature difference during the operation of the water-cooled turbo chiller, and
The value of the logarithmic mean temperature difference in the normal state is the logarithmic mean in the operation using the correlation formula showing the relationship between the COP in the normal state and the logarithmic mean temperature difference without deterioration of the refrigerator performance due to the contamination of the cooling water. The step of calculating the normal COP when the water-cooled turbo chiller is in the normal state when it is the value of the temperature difference, and
The ratio between the operating time of COP and the normal time COP, the steps of diagnosing a heat transfer surface contamination degree in the interior of the condenser of the water-cooled centrifugal chiller,
Only including,
The logarithmic mean temperature difference during operation and the logarithmic mean temperature difference in the normal state are both calculated by the following formula (1), which is a method for diagnosing performance deterioration of a water-cooled turbo chiller.
Record
Logarithmic mean temperature difference _{= (Δt 1 -Δt 2) /} ln (Δt 1 / Δt 2) ··· Equation (1)
However, in the above equation (1), Δt ₁ = T _wo −T _ci and Δt ₂ = T _wi −T _co .
T _wi is the cooling water inlet temperature to the condenser, T _wo is the cooling water outlet temperature from the condenser, T _ci is the chilled water inlet temperature to the evaporator, and T _co is the chilled water outlet temperature from the evaporator. Is. Step further performs diagnosis based on the power increase in the water-cooled centrifugal chiller performance degradation diagnostic method of the water-cooled turbo chiller according to claim 1 of diagnosing the heat transfer surface fouling degree. The step of diagnosing the degree of heat transfer surface contamination is performed based on the ratio of the COP during operation and the COP during normal operation and / or the tendency of the change in the amount of power increase in the water-cooled turbo chiller with time. The method for diagnosing performance deterioration of a water-cooled turbo chiller according to 1 or 2. Claims 1 to 3 further include a step of issuing an alarm when the ratio between the operating COP and the normal COP is not within the preset range and / or when the power increase amount becomes equal to or higher than the preset value. The method for diagnosing performance deterioration of the water-cooled turbo chiller described in any of the above. A condenser, which is a heat exchanger for cooling water and refrigerant,
It is a heat exchanger for water and refrigerant, and is a performance deterioration diagnostic device for diagnosing performance deterioration of a water-cooled turbo chiller including an evaporator that supplies cold water to the outside.
An operating parameter calculation means for calculating the actual operating COP and the operating logarithmic mean temperature difference during operation of the water-cooled turbo chiller, and
The value of the logarithmic mean temperature difference in the normal state is the logarithmic mean in the operation using the correlation formula showing the relationship between the COP in the normal state and the logarithmic mean temperature difference without deterioration of the refrigerator performance due to the contamination of the cooling water. A normal COP calculation means for calculating a normal COP when the water-cooled turbo chiller is in the normal state when it is a value of a temperature difference, and
A diagnostic means for diagnosing the degree of heat transfer surface contamination in the condenser inside the water-cooled turbo chiller from the ratio of the operating COP to the normal COP.
Equipped with
The logarithmic mean temperature difference during operation and the logarithmic mean temperature difference in the normal state are both calculated by the following formula (1), which is a performance deterioration diagnostic device for a water-cooled turbo chiller.
Record
Logarithmic mean temperature difference _{= (Δt 1 -Δt 2) /} ln (Δt 1 / Δt 2) ··· Equation (1)
However, in the above equation (1), Δt ₁ = T _wo −T _ci and Δt ₂ = T _wi −T _co .
T _wi is the cooling water inlet temperature to the condenser, T _wo is the cooling water outlet temperature from the condenser, T _ci is the chilled water inlet temperature to the evaporator, and T _co is the chilled water outlet temperature from the evaporator. Is. It said diagnostic means for diagnosing the heat transfer surface contamination degree on the basis of the power increase amount in the water-cooled centrifugal chiller performance degradation diagnostic apparatus for a water-cooled turbo-refrigerator according to claim 5. Further provided with a recording means for recording the ratio of the operating COP to the normal COP and / or the change over time in the amount of increase in electric power in the water-cooled turbo chiller.
The performance deterioration diagnostic device for a water-cooled turbo chiller according to claim 5 or 6, wherein the diagnostic means diagnoses the degree of heat transfer surface contamination based on the result recorded in the recording means. From claim 5, further comprising an alarm means for issuing an alarm when the ratio between the operating COP and the normal COP is not within the preset range and / or when the power increase amount becomes equal to or more than the preset value. 7. The performance deterioration diagnostic device for the water-cooled turbo chiller according to any one of 7.

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