JP7596036B2 - Method for estimating the performance of heat source equipment - Google Patents

Description

The present invention relates to a method for estimating the performance of an actual heat source device used for air conditioning.

In office buildings, commercial facilities, and various other buildings, the power consumption of the heat source equipment used for air conditioning may need to be calculated when estimating the energy consumption of the air conditioning equipment and creating an operating plan.

The performance of the heat source device is shown, for example, in a diagram as shown in FIG. 7. In the graph of FIG. 7, the COP (Coefficient of Performance) is assumed as a value indicating the performance of the heat source device (hereinafter, in this specification, this will be referred to as the "power characteristic value" as necessary), and the relationship of the COP to the heat source load rate is shown as a curve (referred to as the "power characteristic curve"). In the example shown here, three types of cooling water temperatures (inlet temperatures) are assumed as operating conditions, and the power characteristic curves at each cooling water temperature (A°C, B°C, C°C) are displayed. The heat source load rate on the horizontal axis is the value obtained by dividing the amount of generated heat by the rated amount of generated heat of the heat source device. The COP on the vertical axis is also called the coefficient of performance, and is the value obtained by dividing the amount of generated heat by the consumed power (energy consumption). Note that other conditions (cooling water outlet temperature, flow rate, etc.) are set as fixed values.

A diagram showing the performance of such a heat source device (called a "power characteristic diagram") is provided, for example, by the manufacturer that manufactures and sells the heat source device, or is created from data provided in the form of a table by the manufacturer. Then, under the condition that the cooling water is at a specific temperature (for example, the inlet temperature is A°C), the amount of heat generated according to the heat source load rate and the power consumption (energy consumption) at that time can be obtained from this graph. Note that the graph in Figure 7 shows three patterns of curves corresponding to three types of cooling water temperatures, but power characteristic curves for cases where the cooling water temperature is different from these can also be appropriately created based on the illustrated power characteristic curve and used. For example, if the cooling water temperature is between A°C and B°C, a curve that is halfway between the curve showing A°C and the curve showing B°C can be assumed, and the amount of heat generated and the power consumption (energy consumption) can be obtained based on this curve.

However, such graphs based on manufacturer data are based only on the performance specifications, and do not necessarily represent the same performance in the actual equipment. Heat source equipment performance varies from one to another, and an error of about ±5 to 15% from the specification value is allowed in the performance of the actual equipment. In other words, the performance of a new heat source equipment varies within a range of ±5 to 15% from the specification value. Furthermore, once the heat source equipment starts operating, its performance changes over time due to aging, and the power characteristics gradually deviate from the specification value. For this reason, even if the performance of the heat source equipment is estimated using a graph like that in Figure 7, which is based on the manufacturer's specification values, it may not necessarily be an optimal estimate that corresponds to the performance of the actual equipment.

In order to accurately estimate the performance of an actual machine, it is possible to create a new power characteristic graph like that shown in Figure 7 from data collected during operation of the actual machine, but this requires measuring the COP while changing the heat source load rate for each condition, which is an enormous amount of work. Furthermore, in actual operation, the conditions are rarely as wide as those used in manufacturer tests, so it is difficult to obtain enough data to draw a power characteristic curve.

As a result, various techniques have been proposed to estimate the performance of the actual machine as accurately as possible by assuming a difference between the specification values and the performance of the actual machine and appropriately correcting the data based on the specification values (for example, see Patent Document 1 below).

JP 2019-90585 A

However, many techniques that attempt to estimate the performance of an actual machine by correcting specification values, including the technique described in Patent Document 1, ultimately require the accumulation of a certain amount of data on the actual machine, and it is difficult to perform satisfactory corrections and performance estimates for the overall power characteristics when there is little operating data on the actual machine. In addition, corrections often require complex calculations, and a method has not yet been established that can easily and accurately estimate the performance of an actual heat source device.

In view of the above, the present invention aims to provide a method for estimating the performance of a heat source device that can easily and accurately estimate the performance of the actual heat source device.

The present invention obtains a power characteristic diagram based on the manufacturer's specifications for the performance of the heat source device,
Obtaining operational data by operating the actual heat source device;
Plotting actual machine operation data on the power characteristic diagram;
A data group corresponding to each power characteristic curve according to a manufacturer's specification values is extracted for each power characteristic curve from the operating data plotted on the power characteristic diagram ;
A trimming process is performed to extract data during stable operation of the heat source device ,
For each of the operational data belonging to the data group extracted for each of the power characteristic curves, an actual value of the power consumption ratio is calculated individually as a value representing the power consumption of the actual unit of the heat source device;
Calculating a manufacturer's value of a power consumption ratio as a value representing power consumption from a manufacturer's specification value for each of the operating data;
Calculate the ratio between the actual value of the power consumption ratio for each data and the manufacturer's value of the power consumption ratio under the same operating conditions as the actual value, and create a scatter diagram showing the relationship between the actual value of the power consumption ratio and the manufacturer's value.
Based on the scatter diagram, a linear approximation formula expressing the relationship between the actual measured value of the power consumption ratio and the manufacturer's value is derived;
Based on the approximation formula, the power characteristic value of the heat source device is corrected according to the manufacturer's specification value ;
Creating a power characteristic diagram after the correction
The present invention relates to a method for estimating the performance of a heat source device, characterized by the above.

In the method for estimating the performance of a heat source device of the present invention, the power consumption ratio, which is a relative value to the rated value, can be used as the value representing the power consumption.

In the method for estimating performance of a heat source device according to the present invention, the power consumption ratio is expressed as power consumption ratio [%] = (power consumption / rated value) x 100,
The actual value of the power consumption ratio is calculated from the actual value of the power consumption obtained from the operation data and a rated value based on the manufacturer's specifications,
The approximation of the linear expression can be expressed as Y=aX+b, where X is the actual measured value of the power consumption ratio, Y is the manufacturer's value of the corrected power consumption ratio, and a and b are constants.
In the method for estimating performance of a heat source device of the present invention, the procedure for creating the power characteristic curve includes:
In the first step, the manufacturer's value of the power consumption ratio is substituted for X in Y=aX+b to calculate the corrected power consumption ratio.
In the second step, calculate the corrected power characteristic value = (heat generated under heat source load conditions of the manufacturer's value of the power consumption ratio) / corrected power consumption = 100 x heat generated / (corrected power consumption ratio x rated value),
As a third step, a power characteristic curve can be created by interpolating the points of the corrected power characteristic values.

The heat source device performance estimation method of the present invention has the excellent effect of easily and accurately estimating the performance of the actual heat source device.

4 is a flowchart illustrating an example of a procedure for executing a performance estimation method for a heat source device according to an embodiment of the present invention. 4 is a graph showing an example of actual operation data obtained by operating an actual machine plotted on a power characteristics diagram. FIG. 3 is a diagram for explaining a state in which data on operating conditions corresponding to each power characteristic curve is extracted from the data plotted in the graph of FIG. 2 . FIG. 11 is a scatter diagram showing an example of the relationship between the actual measured value and the manufacturer's value of the power consumption ratio. 11 is a graph showing an example of a power characteristic curve before and after correction. 11 is a graph showing an example of a power characteristic diagram before and after correction. 4 is a graph showing an example of a power characteristic diagram of a heat source device.

The following describes an embodiment of the present invention with reference to the attached drawings.

Figure 1 is a flowchart showing an example of the procedure for executing a method for estimating the performance of a heat source device according to the present invention. Below, the procedure for estimating the performance of a heat source device will be explained based on this flowchart.

First, a power characteristic diagram based on the manufacturer's specifications is obtained (step S1). This power characteristic diagram may be provided by the manufacturer itself, or a curve graph may be created from data including power characteristic values (COP) listed in documents such as catalogs and specifications provided by the manufacturer. The power characteristic diagram obtained here is, for example, a graph like that shown in Figure 7.

Next, the actual device is operated to obtain the operating data required to understand the power characteristics of the heat source device (step S2). This actual device is a heat source device that is incorporated into an air conditioning system that is actually in commercial operation in an office building, hospital, factory, etc., and operates according to actual fluctuations in outside air and load. The operating data can be obtained, for example, from the log of the control device of the heat source device that constitutes the air conditioning system. That is, a control device called an EMS (Energy Management System) or the like records various data related to the operation of the actual device of the heat source device, such as the actual measured value of the power consumption of the heat source device, the load heat amount, the flow rate of the cooling water, the inlet temperature of the cooling water, etc., from time to time, so the necessary data can be obtained from the log of this control device.

The data obtained in step S2 is plotted on the power characteristics diagram (see Figure 7) obtained in step S1 (step S3). The plotted data for each point in time is, for example, as shown in Figure 2. That is, the heat source load factor at each point in time during operation of the actual machine and the coefficient of performance (COP) that represents the power characteristics at that time can be obtained from the data obtained in step S2, and Figure 2 is a graph in which these data at each point in time are plotted on the power characteristics diagram of Figure 7 in accordance with multiple cooling water temperatures.

As shown in FIG. 2, from the data plotted on the power characteristic diagram, a data group corresponding to each power characteristic curve is extracted for each power characteristic curve in step S4 (stratified processing). Here, "data group corresponding to each power characteristic curve" refers to "actual data group acquired under operating conditions (cooling water inlet temperature, cooling water flow rate, chilled water outlet temperature, and heat source load factor) that match each power characteristic curve." Since each power characteristic curve shown in FIG. 7 and FIG. 2 is premised on a certain operating condition (cooling water temperature, etc.), for each power characteristic curve, actual data collected under operating conditions that match the operating conditions set for that power characteristic curve are selected. In FIG. 2, actual data corresponding to the power characteristic curve when the cooling water temperature (inlet temperature) is A°C is represented by a circle symbol, actual data corresponding to the power characteristic curve when the cooling water temperature is B°C is represented by a triangle symbol, and actual data corresponding to the power characteristic curve when the cooling water temperature is C°C is represented by a square symbol. That is, in step S4, data represented by circles is extracted for the power characteristic curve at A°C, data represented by triangles is extracted for the power characteristic curve at B°C, and data represented by squares is extracted for the power characteristic curve at C°C.

Note that "matching operating conditions" here does not necessarily mean that all operating conditions are strictly the same. It also means that operating conditions are similar enough that they can be treated as the same in practical terms. It also includes some of the operating conditions being the same.

At this time, data that further satisfies certain requirements is selected and extracted as data to be used in deriving the approximation formula and correcting the dynamic characteristic value in step S5 (trimming process). Specifically, for example, data that falls under the following conditions may be excluded.
- Data for a period of time (e.g. 30 minutes) after the actual heat source device is started. This is because the energy consumption until stable and continuous production of cold water can be used in the approximation formula. Note that cooling water is used to remove the waste heat used to produce cold water. For example, the inlet temperature of a heat source device such as a refrigerator condenser is 32°C and the outlet temperature is 37°C, so even if the inlet temperature changes, the outlet temperature will be relatively higher.
- Data for low load (for example, when the heat source load rate is below 30%). When the heat source load rate is below the lower limit for continuous operation, the heat source device may operate in on/off mode rather than continuous mode, and data may be collected when the device is not operating steadily.
Data when the heat source is stopped, to avoid the data at the origin of the scatter diagram (see Figure 4; explained later) affecting the approximation formula.
- Data from operations under conditions different from normal operation, such as during maintenance, to avoid the effect on the approximation formula due to operating conditions different from normal operation (for example, changes in the cooling water flow rate).

For each of the operational data belonging to the data groups extracted for each power characteristic curve in this way, the relative value of the actual power consumption (actual measured value) to the rated value of the power consumption of the heat source unit (hereinafter referred to as the "power consumption ratio") is calculated individually (step S6). In step S4, the data groups corresponding to each power characteristic curve (the group indicated by ○ for the power characteristic curve with a cooling water temperature of A°C in Figure 2, the group indicated by △ for the power characteristic curve with a cooling water temperature of B°C, and the group indicated by □ for the power characteristic curve with a cooling water temperature of C°C in Figure 2) were extracted, and in this step S6, the power consumption ratio is calculated for each of the data extracted in this way (the individual data corresponding to each point indicated by ○, △, or □ in Figure 2).

The power consumption ratio can be expressed, for example, by the following formula, and the actual value of the power consumption ratio can be calculated from the actual value of power consumption obtained from operating data and a rated value based on the manufacturer's specifications.
Power consumption ratio [%] = (power consumption / rated value) x 100 … (1)

Next, for each operating data (individual data corresponding to each point represented by ○, △, or □ in FIG. 2), the specified value of the power consumption ratio (hereinafter referred to as the "manufacturer's value of the power consumption ratio") is calculated from the manufacturer's specification value under the same conditions (cooling water temperature and heat source load rate) (step S7). This manufacturer's value of the power consumption ratio can be calculated using the above formula (1) based on the power characteristic diagram according to the manufacturer's specification values as shown in FIG. 7. That is, if a certain cooling water temperature and heat source load rate are given as conditions, the COP according to the manufacturer's specification values under the same conditions can be obtained from the power characteristic diagram shown in FIG. 7. Furthermore, the power consumption can be obtained as the product of the load heat amount in the heat source device and the reciprocal of the COP, and the load heat amount is obtained as the product of the rated capacity of the heat source device and the heat source load rate, so the manufacturer's value of the power consumption ratio can be obtained from the power characteristic diagram in FIG. 7 and the above formula (1).

In this way, through steps S6 and S7, the actual measured value of the power consumption ratio for each data and the manufacturer's value of the power consumption ratio under the same operating conditions (cooling water temperature and heat source load factor) were calculated. In the following step S8, these ratios are calculated. Furthermore, the same process is repeated for each operating data, and a scatter diagram is created that shows the relationship between the actual measured value of the power consumption ratio and the manufacturer's value, as shown in Figure 4.

Based on the scatter diagram created in step S8, an approximation formula expressing the relationship between the actual measured value of the power consumption ratio and the manufacturer's value is derived (step S9). If the approximation formula is a simple linear formula such as the following formula (2), the approximation formula can be derived easily and the power characteristic value can be corrected thereafter. X is the actual measured value of the power consumption ratio, Y is the manufacturer's value of the power consumption ratio after correction, and a and b are constants. The relationship expressed by this approximation formula is shown by the dashed line in FIG. 4.
Y=aX+b...(2)

The approximation formula created here is not limited to a linear formula such as formula (2) above, but may be, for example, a quadratic formula, a cubic formula, or any other type of formula. The type of formula to be created as the approximation formula can be determined appropriately depending on the appearance of the scatter diagram that is actually created.

Furthermore, among the power characteristic values (COP) acquired as manufacturer specifications, the values belonging to the corresponding power characteristic curve are corrected based on the above formula (2) (step S10). For example, in the previous steps S8 and S9, if the scatter diagram was created and the approximation formula was derived based on the actual measurement data corresponding to the points indicated by circles in Figure 2, the coefficient of performance value, which is the power characteristic of the actual machine corresponding to the power characteristic curve when the cooling water temperature is A°C, is corrected.

If the power consumption ratio is calculated based on the power characteristic values provided by the manufacturer, each of these will be a value corresponding to X on the right-hand side of the above formula (2), but these values are corrected to values such that the value corresponding to Y on the left-hand side is calculated as the power consumption ratio. Next, a power characteristic diagram is recreated based on the corrected power characteristic values (step S11). The power characteristic curve in the recreated power characteristic diagram will be, for example, a curve such as that shown by the dashed line in Figure 5. The solid line indicates the power characteristic curve according to the manufacturer's specification values. The procedure for creating the power characteristic curve will be explained below.
(1) Substitute the manufacturer's value of the power consumption ratio (e.g., multiple values in 10% increments) for X in Y = aX + b to calculate the corrected power consumption ratio. (2) Calculate the corrected COP value = heat generated (under the heat source load condition of the manufacturer's value of the power consumption ratio) / corrected power consumption = 100 x heat generated / (corrected power consumption ratio x rated value). (3) Create a COP curve by interpolating each point of the corrected COP value.

By repeating steps S6 to S11 above for each data group corresponding to each power characteristic curve, it is possible to finally obtain power characteristic curves for all power characteristic curves that have been corrected based on the operating data of the actual machine, as shown in Figure 6.

According to the method of the present embodiment described above, it is possible to obtain a highly accurate power characteristic diagram based on the operating data of the actual machine, even if there is little data obtained by operating the actual machine, compared to the case of using the old method of redrawing the power characteristic curve using the operating data of the actual machine. In other words, if you try to redraw the power characteristic curve using only the operating data of the actual machine, you need to collect a considerable amount of data to obtain a power characteristic curve with sufficient accuracy for practical use, but in the method of this embodiment, the operating data of the actual machine is used to correct the power characteristic curve based on the manufacturer's specifications, so much less actual measurement data is required compared to redrawing the power characteristic curve using only the operating data of the actual machine.

In addition, when making the correction, an approximation formula is created using the heat source load rate and power consumption, which is a value related to COP, and the discrepancy between the manufacturer's value and the actual measured value is corrected, so good corrections can be made with just a very simple calculation. If a linear formula is used as the approximation formula, the necessary calculation processing is even simpler.

In addition, in a method such as this embodiment, only data that matches the operating conditions (cooling water temperature and other various conditions) of each power characteristic curve based on the manufacturer's values is extracted from the actual measurement data and used for correction. However, in many cases, the actual machine is operated only under somewhat limited operating conditions. For this reason, it is difficult to obtain a power characteristic curve that is corrected over the entire range using a method such as this embodiment. However, when trying to estimate the performance of a heat source device for the purpose of calculating the energy consumption of an air conditioning system and planning an operation plan, for example, it is sufficient to understand the performance under somewhat limited operating conditions, so in practice it is not necessarily necessary to correct the power characteristic curve over the entire range.

The above steps can be summarized as follows. When the relationship between heat source load rate and COP is plotted on a power characteristics diagram for the operating data at a certain point obtained in step S2, it is assumed to be at the point indicated by reference symbol P1 in FIG. 2. The operating data at the point corresponding to this point P1 includes the heat source load rate and COP as well as the cooling water flow rate and temperature (inlet temperature). Therefore, it is also possible to calculate the COP value (manufacturer's value) according to the specifications under the same conditions as the operating data at the point corresponding to this point P1. This manufacturer's value is plotted at the point indicated by reference symbol P2, for example.

Then, the actual power consumption ratio is calculated based on the data corresponding to point P1 (step S6), and the manufacturer's value of the power consumption ratio is calculated based on the data corresponding to point P2 (step S7), and these ratios are calculated. This is done for each data, a scatter diagram is created (step S8), and an approximation formula is derived (step S9). The approximation formula thus obtained is applied to the corresponding power characteristic curve (steps S10, S11), and a corrected power characteristic curve is obtained (see Figure 5). By repeating this for each power characteristic curve, an overall corrected power characteristic diagram can be obtained, as shown in Figure 6.

The above procedure is merely an example, and when implementing the present invention, the content of some of the steps may be changed, the order of the steps may be changed, or other appropriate modifications may be made. For example, the calculation of the actual power consumption ratio in step S6 and the calculation of the manufacturer's value in step S7 may be switched around, or may be performed simultaneously in parallel.

For the sake of convenience, the above description describes the procedure of plotting the operating data on a power characteristic diagram in step S3 and then extracting the operating data corresponding to each power characteristic curve, but the extraction of operating data does not necessarily require the creation of a scatter diagram. It is also possible to extract operating data that matches specific operating conditions (cooling water temperature and various other conditions) without creating a scatter diagram, and use the extracted data to execute subsequent steps.

In addition, the above describes the case where the relationship between the actual measured value of power consumption and the manufacturer's value is calculated as a relative value (power consumption ratio), but when creating a scatter diagram such as that shown in Figure 4 or deriving an approximation formula such as that shown in equation (2), it is also possible to use absolute values rather than relative values to represent the power consumption. In that case, the actual measured value can be the power consumption value itself obtained from the operating data. Also, the manufacturer's value can be calculated using a power characteristic diagram such as that shown in Figure 7.

As described above, in the above embodiment, a data group corresponding to the power characteristic curve according to the manufacturer's specification values is extracted from the operating data obtained by operating the actual heat source device, an approximation formula is derived that represents the relationship between the actual measured value of the value representing the power consumption of the heat source device in the extracted operating data and the manufacturer's value of the value representing the power consumption, and the coefficient of performance value that represents the power characteristics of the heat source device according to the manufacturer's specification values is corrected based on the approximation formula. In this way, by correcting the power characteristic value according to the manufacturer's specification values using the operating data of the actual device, it is possible to obtain a highly accurate power characteristic diagram based on the operating data of the actual device even if there is little data obtained by operating the actual device. In this case, an approximation formula is created using the heat source load rate and the power consumption, which is a value related to the COP, and good correction can be made with simple calculations by correcting the difference between the manufacturer's value and the actual measured value.

In addition, in this embodiment, the approximation formula can be a linear formula, which makes it easy to derive the approximation formula and correct the power characteristic values.

In addition, in this embodiment, the power consumption ratio, which is a relative value to the rated value, can be used as a value representing the power consumption.

Therefore, according to the above embodiment, the performance of the actual heat source device can be easily and accurately estimated.

The method for estimating the performance of a heat source device of the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit of the present invention.

Claims (4)

Obtain a power characteristic diagram based on the manufacturer's specifications for the performance of the heat source equipment,
Obtaining operational data by operating the actual heat source device;
Plotting actual machine operation data on the power characteristic diagram;
A data group corresponding to each power characteristic curve according to a manufacturer's specification values is extracted for each power characteristic curve from the operating data plotted on the power characteristic diagram ;
A trimming process is performed to extract data during stable operation of the heat source device ,
For each of the operational data belonging to the data group extracted for each of the power characteristic curves, an actual value of the power consumption ratio is calculated individually as a value representing the power consumption of the actual unit of the heat source device;
Calculating a manufacturer's value of a power consumption ratio as a value representing power consumption from a manufacturer's specification value for each of the operating data;
Calculate the ratio between the actual value of the power consumption ratio for each data and the manufacturer's value of the power consumption ratio under the same operating conditions as the actual value, and create a scatter diagram showing the relationship between the actual value of the power consumption ratio and the manufacturer's value.
Based on the scatter diagram, a linear approximation formula expressing the relationship between the actual measured value of the power consumption ratio and the manufacturer's value is derived;
Based on the approximation formula, the power characteristic value of the heat source device is corrected according to the manufacturer's specification value ;
Creating a power characteristic diagram after the correction
A method for estimating performance of a heat source device, comprising: The method for estimating performance of a heat source device according to claim 1 , wherein a power consumption ratio, which is a relative value with respect to a rated value, is used as the value representing the power consumption. The power consumption ratio is expressed as power consumption ratio [%] = (power consumption / rated value) x 100,
The actual value of the power consumption ratio is calculated from the actual value of the power consumption obtained from the operation data and a rated value based on the manufacturer's specifications,
The performance estimation method of the heat source device according to claim 1, characterized in that the approximation equation of the linear expression is expressed as Y = aX + b, where X is the actual measured value of the power consumption ratio, Y is the manufacturer's value of the power consumption ratio after correction, and a and b are constants. The procedure for creating the power characteristic curve is as follows:
In the first step, the manufacturer's value of the power consumption ratio is substituted for X in Y=aX+b to calculate the corrected power consumption ratio.
In the second step, calculate the corrected power characteristic value = (generated heat amount under heat source load conditions of the manufacturer's value of the power consumption ratio) / corrected power consumption = 100 x generated heat amount / (corrected power consumption ratio x rated value),
4. The method for estimating performance of a heat source device according to claim 3, further comprising the step of: generating a power characteristic curve by interpolating each point of the corrected power characteristic value in a third step.

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