JP2022016974A - Heat collecting system and control method for the same - Google Patents

Abstract

To provide a heat collecting system enabling more efficient pump control and a control method for the heat collecting system.SOLUTION: A heat collecting system 1 includes: a solar collector 10; a heat storage tank 20; a heat collecting pump P serving as a power source for circulating a heating medium between the solar collector 10 and the heat storage tank 20; a first calculation section 41 calculating heat collecting amount that can be obtained in the solar collector 10; a second calculation section 42 calculating heat collecting system efficiency obtained by dividing the heat collecting amount calculated by the first calculation section 41 by electric power consumption of the heat collecting pump P; and a pump control section 43 operating the heat collecting pump P when a heat collecting COP calculated by the second collection section 42 is COPON or greater and stopping the heat collecting pump P when the heat collecting COP calculated by the second collection section 42 is smaller than COPOFF.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heat collecting system and a control method thereof.

Conventionally, a heat collecting system that collects heat using solar heat is known (see, for example, Patent Document 1). In this heat collecting system, for example, a heat medium is circulated between a solar heat collector and a heat storage tank. A heat collecting pump is used to circulate the heat medium. In the heat collecting system, the heat collecting pump is differentially controlled so that the temperature difference (T1'-T2') at the inlet and outlet of the solar heat collector operates at a temperature difference of Th or more and stops at Tl (temperature less than Th) or less. ing.

Japanese Unexamined Patent Publication No. 2017-166783

However, the above heat collecting pump is controlled only by the temperature difference (T1'-T2') at the inlet and outlet of the solar heat collector, and is operated when the actual heat collecting amount is not high, or the heat collecting amount. It may stop when the temperature is high. Therefore, for example, there is a problem that the heat collecting pump stops if the temperature difference (T1'-T2') is Tl or less even under the condition that heat collection can be expected to some extent due to solar radiation. ..

Further, the heat collecting pump is also controlled to change the flow rate so that the outlet temperature T1'of the solar heat collector becomes a predetermined temperature. However, even in this case, since the heat collecting pump is controlled by the outlet temperature T1', it cannot be said that good control is performed in terms of the amount of heat collected.

In addition, there are various types of heat collecting pumps used, and each has different power consumption. Therefore, depending on the type of heat collecting pump, the standard of the amount of heat collected to operate the heat collecting pump also differs. Even if the heat collecting pump is started or stopped based on the amount of heat, it cannot be said that proper pump control is performed.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a heat collecting system capable of performing more efficient pump control and a control method thereof. There is something in it.

The heat collecting system according to the present invention is a solar heat collector that heats a heat medium by heat obtained by receiving sunlight, and a heat storage tank that stores heat based on the heat medium heated by the solar heat collector. In a heat collecting system including a heat collecting pump as a power source for circulating a heat medium between the solar heat collector and the heat storage tank, the amount of heat collected by the solar heat collector can be obtained. Calculated by the first calculation means to be calculated, the second calculation means to calculate the heat collection system efficiency obtained by dividing the heat collection amount calculated by the first calculation means by the power consumption of the heat collection pump, and the second calculation means. When the heat collection system efficiency is equal to or higher than the first predetermined value, the heat collection pump is operated, and the heat collection system efficiency calculated by the second calculation means is less than the second predetermined value of the first predetermined value or less. A pump control means for stopping the heat collecting pump when the heat is collected is provided.

Further, the control method of the heat collecting system according to the present invention is based on a solar heat collector that heats a heat medium by heat obtained by receiving sunlight and a heat medium heated by the solar heat collector. In a control method of a heat collection system including a heat storage tank for storing heat and a heat collection pump as a power source for circulating a heat medium between the solar heat collector and the heat storage tank, the solar heat collection A first calculation step for calculating the amount of heat collected in the heat generator, and a second calculation step for calculating the efficiency of the heat collecting system obtained by dividing the amount of heat collected calculated in the first calculation step by the power consumption of the heat collecting pump. The first pump control step for operating the heat collecting pump when the heat collecting system efficiency calculated in the second calculation step is equal to or higher than the first predetermined value, and the heat collecting system calculated in the second calculation step. The present invention comprises a second pump control step of stopping the heat collecting pump when the efficiency is less than or equal to the first predetermined value and less than the second predetermined value.

According to the present invention, it is possible to provide a heat collecting system capable of performing more efficient pump control and a control method thereof.

It is a block diagram which shows the heat collecting system which concerns on embodiment of this invention. It is a conceptual diagram which shows the correlation data stored by a control device. It is a conceptual diagram which shows the operation control of the heat collecting pump by the pump control part shown in FIG. It is a flowchart which shows the control method of the heat collection system which concerns on embodiment of this invention. It is a flowchart which shows an example of the heat collection amount calculation process shown in FIG. It is a flowchart which shows the other example of the heat collection amount calculation process shown in FIG.

Hereinafter, the present invention will be described with reference to preferred embodiments. The present invention is not limited to the embodiments shown below, and can be appropriately modified without departing from the spirit of the present invention. Further, in the embodiments shown below, some parts of the configuration are omitted from the illustration and description, but the details of the omitted technology are within a range that does not cause any contradiction with the contents described below. Needless to say, publicly known or well-known techniques are applied as appropriate.

FIG. 1 is a block diagram showing a heat collecting system according to an embodiment of the present invention. The heat collecting system 1 shown in FIG. 1 includes a solar heat collector 10, a heat storage tank 20, a heat collecting pump P, pipes R1 to R4, various sensors T1 to T3, Ta, 30 and a control device 40. I have.

The solar heat collector 10 is installed on the roof of a sunny house or building, and heats a heat medium (for example, hot water) by the heat obtained by receiving sunlight. The solar heat collector 10 and the heat storage tank 20 are connected by a first circulation pipe R1 and a second circulation pipe R2. More specifically, the first circulation pipe R1 connects the lower part of the heat storage tank 20 and the solar heat collector 10. Further, the second circulation pipe R2 connects the solar heat collector 10 and the upper part of the heat storage tank 20. The first circulation pipe R1 and the second circulation pipe R2 are configured such that a heat medium flows inside.

The heat storage tank 20 stores heat by storing the heat medium heated by the solar heat collector 10. The heat collecting pump P serves as a power source for circulating a heat medium between the solar heat collector 10 and the heat storage tank 20, and is provided on the first circulation pipe R1. When the heat collecting pump P operates, the heat medium circulates between the solar heat collector 10 and the heat storage tank 20. More specifically, the heat medium at the bottom of the heat storage tank 20 (the heat medium having a relatively low temperature among the heat media in the heat storage tank 20) is supplied to the solar heat collector 10, and the heat heated by the solar heat collector 10 is supplied. The medium is returned to the upper part of the heat storage tank 20. The heat collecting pump P may be provided on the second circulation pipe R2.

The heat medium going pipe R3 and the heat medium returning pipe R4 circulate the equipment that uses hot water and the heat medium. For example, when the device that uses hot water is a hot water-fired absorption type cold / hot water machine, the heat medium at the upper part of the heat storage tank 20 is supplied to the regenerator of the hot water-fired absorption type cold / hot water machine via the heat medium flow pipe R3 and absorbed. After being used for liquid regeneration and lowering in temperature, it is returned to the lower part of the heat storage tank 20 through the heat medium return pipe R4.

The first temperature sensor T1 is for measuring the heat medium temperature at the outlet of the solar heat collector 10, and is provided on the solar heat collector 10 side of the second circulation pipe R2. The second temperature sensor T2 is provided at the lower part of the heat storage tank 20 for measuring the heat medium temperature at this position, and the third temperature sensor T3 is provided at the upper part of the heat storage tank 20 at this position. It is for measuring the temperature of the heat medium. The outside air temperature sensor Ta is for measuring the outside air temperature around the heat collecting system 1 (particularly the solar heat collector 10). The solar radiation amount sensor 30 is for measuring the amount of solar radiation, and is provided so as to face the same direction at a position near the solar heat collector 10, for example, in order to measure the amount of solar radiation with respect to the solar heat collector 10. Signals from various sensors T1 to T3, Ta, 30 are transmitted to the control device 40.

The control device 40 controls the entire heat collecting system 1, and in the present embodiment, controls the operation of the heat collecting pump P. The control device 40 controls the operation of the heat collecting pump P based on the signals from various sensors T1 to T3, Ta, 30. Such a control device 40 includes a first calculation unit (first calculation means) 41, a second calculation unit (second calculation means) 42, and a pump control unit (pump control means) 43.

The first calculation unit 41 calculates the amount of heat collected by the solar heat collector 10. The first calculation unit 41 calculates the heat collection amount [kJ] from the formula of heat collection efficiency × heat collection area [m ² ] × solar radiation amount [kJ / m ² ]. Here, the heat collecting area corresponds to the area of the solar heat collector 10, and is stored in advance in, for example, the control device 40. As the amount of solar radiation, a value measured based on the signal from the amount of solar radiation sensor 30 is used.

The heat collection efficiency η is calculated from the difference Δθ between the temperature of the solar heat collector 10 and the outside air temperature, the total amount of solar radiation I, and the correlation data shown in FIG. For the temperature difference Δθ, the heat medium temperature measured based on the signal from the first temperature sensor T1 is the temperature of the solar heat collector 10, and the outside air temperature measured based on this temperature and the signal from the outside air temperature sensor Ta. The difference with is adopted. As the total solar radiation amount I, a value measured based on the signal from the solar radiation amount sensor 30 is used. As for the temperature of the solar heat collector 10, the temperature on the outlet side of the heat medium is adopted because the first temperature sensor T1 according to the present embodiment measures the temperature of the heat medium at the outlet of the solar heat collector 10. However, the present invention is not limited to this, and the inlet side temperature of the solar heat collector 10 may be adopted, or the average temperature between the inlet side and the outlet side may be adopted. In this case, it goes without saying that a temperature sensor is provided on the inlet side of the solar heat collector 10. In the following, it will be described that the detection temperature based on the first temperature sensor T1 is adopted as the temperature of the solar heat collector 10.

FIG. 2 is a conceptual diagram showing correlation data stored by the control device 40. As shown in FIG. 2, the thermal collection efficiency η can be calculated from a0−a1 × (Δθ / I) −a2 × (Δθ / I) ² . Here, a0, a1, and a2 are constants. The constants a0, a1 and a2 may be known values (values stored in advance) disclosed by the manufacturer of the solar heat collector 10 or the like, or may be the first value based on the installation status of the solar heat collector 10 or the like. 1 The value may be corrected by the calculation unit 41.

As described above, the first calculation unit 41 has the heat collection efficiency based on the correlation data shown in FIG. 2, the signal from the first temperature sensor T1, the signal from the outside air temperature sensor Ta, and the signal from the solar radiation amount sensor 30. Calculate η.

The first calculation unit 41 is not limited to the above, and the heat collection amount [kJ] is obtained from the calculation formula of heat medium flow rate [kg / h] × heat collector inlet / outlet temperature difference [K] × specific heat [kJ / kg · K]. ] May be calculated. The heat medium flow rate is detected by newly providing a flow rate sensor in the first circulation pipe R1. Not limited to this, if the heat collecting pump P has a constant flow rate, the flow rate may be measured in advance and stored in the control device 40. Regarding the temperature difference between the inlet and outlet of the collector, a temperature sensor may be newly provided on the inlet side of the solar heat collector 10, and the temperature difference between this and the first temperature sensor T1 may be adopted, or from the second temperature sensor T2. The temperature measured based on the signal of the above may be set as the temperature on the inlet side of the solar heat collector 10, and the temperature difference between this and the first temperature sensor T1 may be adopted. As for the specific heat, a value stored in advance in the control device 40 may be adopted, or may be calculated each time from the heat medium temperature.

The second calculation unit 42 calculates the heat collection system efficiency (hereinafter referred to as heat collection COP) obtained by dividing the heat collection amount calculated by the first calculation unit 41 by the power consumption of the heat collection pump P. As a result, the second calculation unit 42 calculates the amount of heat collected with respect to the power consumption (energy consumption) of the heat collecting pump P, and calculates a value indicating whether or not heat can be collected more efficiently. The second calculation unit 42 may measure the power consumption based on the signal from the wattmeter or the like, or may adopt the power consumption stored in advance according to the type of the heat collecting pump P or the like. ..

The pump control unit 43 controls the operation of the heat collecting pump P. FIG. 3 is a conceptual diagram showing operation control of the heat collecting pump P by the pump control unit 43 shown in FIG. As shown in FIG. 3, in the pump control unit 43, when the heat collection COP calculated by the second calculation unit 42 is COP _ON (first predetermined value) or more in a state where the heat collection pump P is stopped. Operates the heat collecting pump P. Further, the pump control unit 43 is in a state where the heat collecting pump P is operating, and when the heat collecting COP calculated by the second calculating unit 42 is less than COP _OFF (second predetermined value), the heat collecting pump P To stop. COP _OFF is a value equal to or less than COP _ON . In particular, the _COPON value is set to a value that is less efficient than other devices such as boilers or other systems.

As described above, since the heat collecting system 1 according to the present embodiment operates or stops the heat collecting pump P based on the heat collecting COP, the amount of heat collected is larger than the power consumption of the heat collecting pump P. The heat collecting pump P can be operated to collect heat in a situation where the heat can be expected, and the pump can be controlled more efficiently.

FIG. 4 is a flowchart showing a control method of the heat collecting system 1 according to the embodiment of the present invention. The process shown in FIG. 4 is repeatedly executed until the power of the control device 40 of the heat collecting system 1 is turned off.

First, as shown in FIG. 4, the first calculation unit 41 of the control device 40 executes the heat collection amount calculation process (S1). As a result, the amount of heat collected by the solar heat collector 10 is calculated. Next, the second calculation unit 42 measures the power consumption of the heat collecting pump P (S2). A predetermined value may be adopted for the power consumption of the heat collecting pump P. Next, the second calculation unit 42 calculates the heat collection COP by dividing the heat collection amount calculated in step S1 by the power consumption measured in step S2 (S3).

After that, the pump control unit 43 determines whether or not heat can be collected (S4). In this process, the pump control unit 43 determines whether to operate or stop the heat collecting pump P as described with reference to FIG. When the pump control unit 43 determines to operate the heat collecting pump P (S4: ON), the pump control unit 43 operates the heat collecting pump P (S5). After that, the process proceeds to step S7.

On the other hand, when the pump control unit 43 determines that the heat collecting pump P is not operated (S4: OFF), the pump control unit 43 stops the heat collecting pump P (S6). After that, the process proceeds to step S7.

In step S7, the control device 40 determines whether a certain time has elapsed from the previous heat collection amount calculation process (S1) (S7). In this process, it is not limited to the case where it is determined whether a certain time has elapsed from the previous heat collection amount calculation process (S1), for example, it is determined whether a certain time has elapsed from the start time of the process shown in FIG. Alternatively, it may be determined whether a certain period of time has elapsed from the time when the operation and the stop of the heat collecting pump P were switched last time. If the fixed time has not elapsed (S7: NO), this process is repeated until the fixed time has elapsed. On the other hand, when a certain time has elapsed (S7: YES), the process shown in FIG. 4 ends.

FIG. 5 is a flowchart showing an example of the heat collection amount calculation process (S1) shown in FIG. As shown in FIG. 5, first, the control device 40 measures the amount of solar radiation and the outside air temperature based on the signals from the solar radiation amount sensor 30 and the outside air temperature sensor Ta (S11). Next, in steps S12 to S14, the control device 40 uses the constants a0, of the equation (heat collection efficiency η = a0-a1 × (Δθ / I) −a2 × (Δθ / I) ² ) described with reference to FIG. Data for correcting a1 and a2 (known values (pre-stored values) disclosed in advance by the manufacturer of the solar heat collector 10 and the like) are acquired.

That is, first, the control device 40 reads the installation angle, installation direction, installation coordinates, and current time data of the solar heat collector 10. (S12). Next, the control device 40 calculates the solar radiation incident angle of the solar heat collector 10 (S13). Next, the control device 40 reads the heat medium condition (heat medium physical characteristic value and flow rate) (S14).

After that, the control device 40 measures the temperature of the solar heat collector 10 (S15). Next, the first calculation unit 41 obtains known values (pre-stored values) a0, a1, a2 disclosed by the manufacturer of the solar heat collector 10 and the like from the data and the like obtained in steps S12 to S14. Along with the correction, the heat collection efficiency η is calculated by applying the solar radiation amount I and the temperature difference ΔT based on the measured values obtained in steps S11 and S15 to the relational expression (S16). Next, the first calculation unit 41 calculates the heat collection amount [kJ] from the formula of heat collection efficiency × heat collection area [m ² ] × solar radiation amount [kJ / m ² ] (S17). After that, the process shown in FIG. 5 ends.

FIG. 6 is a flowchart showing another example of the heat collection amount calculation process (S1) shown in FIG. As shown in FIG. 6, first, the control device 40 measures the heat medium flow rate (S21). After that, the inlet / outlet temperature of the solar heat collector 10 is measured (S22). After that, the first calculation unit 41 calculates the heat collection amount [kJ] from the calculation formula of heat medium flow rate [kg / h] × heat collector inlet / outlet temperature difference [K] × specific heat [kJ / kg · K] ( S23). After that, the process shown in FIG. 6 ends.

In this way, according to the heat collecting system 1 and the control method thereof according to the present embodiment, the heat collecting amount that can be acquired in the solar heat collecting device 10 is calculated, and the heat collecting COP divided by the power consumption of the heat collecting pump P is calculated. In order to calculate and control the operation of the heat collecting pump P based on the heat collecting COP, when the ratio of the amount of heat collected to the power consumed when the heat collecting pump P is operated is somewhat high. By turning on the heat collecting pump P, the heat collecting pump P can be operated efficiently with respect to power consumption. Therefore, more efficient pump control can be performed.

Further, when the heat collecting pump P is operated or stopped based on the heat collecting COP calculated by the second calculation unit 42, the pump control unit 43 maintains the operating state of the heat collecting pump P for a certain period of time. .. Therefore, it is possible to suppress a decrease in efficiency due to repeated operation and stop without switching the operating state of the heat collecting pump P frequently.

Further, when the operation control of the heat collecting pump P based only on the temperature difference is performed as in the conventional case, the control may be inefficient unless the set value of the temperature difference is tuned according to the annual weather change. When the operation of the heat collecting pump P is controlled based on the heat collecting COP, there is no need for tuning.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and changes may be made without departing from the spirit of the present invention. May be combined.

For example, the heat collecting system 1 according to the present embodiment supplies hot water from the heat storage tank 20 to the solar heat collector 10 to heat the hot water, but the present invention is not particularly limited to this, and heat is stored in the heat storage tank 20. An exchanger may be provided, and an antifreeze liquid (heat medium) may be circulated between the solar heat collector 10 and the heat exchanger.

Further, in the above-mentioned flowchart, the order of processing is not limited to that shown in the figure. For example, in steps S1 and S2 shown in FIG. 4, the process of step S2 may be executed first, and the processes of steps S11 to S14 shown in FIG. 5 may be performed in step S13 rather than the process of step S12. If the processing of is later, the order of other processing may be changed. The processes of steps S21 and S22 of FIG. 6 may be interchanged in the same manner.

Further, when calculating the heat collection efficiency η based on FIG. 2, the heat collection efficiency diagram may be calculated as it is using the heat collection efficiency diagram disclosed by the manufacturer, or the line is further corrected for efficiency according to the flow rate and the number of sheets installed in series. It may be calculated from the figure. Further, the horizontal axis of the heat collection efficiency diagram is generally Δθ / I, but may be Δθ.

Further, the calculation of the heat collecting COP and the set COP _ON and COP _OFF values may include the heat loss of the system circuit such as the heat collecting piping loss. In addition, in the present embodiment, the operation of the heat collecting pump P is controlled from the current measurement data and the like, but the prediction calculation is performed from the measured data such as the amount of solar radiation, and the predicted calculation data is obtained. The operation of the heat collecting pump P may be controlled based on the above.

1: Heat collecting system 10: Solar heat collector 20: Heat storage tank 30: Solar radiation amount sensor 40: Control device 41: First calculation unit (first calculation means)
42: Second calculation unit (second calculation means)
43: Pump control unit (pump control means)
P: Heat collecting pump

Claims (3)

A solar heat collector that heats a heat medium with heat obtained by receiving sunlight, a heat storage tank that stores heat based on the heat medium heated by the solar heat collector, and the solar heat collector and the above. In a heat collection system equipped with a heat collection pump that serves as a power source for circulating a heat medium to and from a heat storage tank.
The first calculation means for calculating the amount of heat collected by the solar heat collector, and
The second calculation means for calculating the heat collection system efficiency obtained by dividing the heat collection amount calculated by the first calculation means by the power consumption of the heat collection pump, and the second calculation means.
When the heat collection system efficiency calculated by the second calculation means is equal to or higher than the first predetermined value, the heat collection pump is operated, and the heat collection system efficiency calculated by the second calculation means is the first predetermined value. A pump control means for stopping the heat collecting pump when the value is less than the second predetermined value below, and
A heat collecting system characterized by being equipped with. When the heat collecting pump is operated or stopped based on the heat collecting system efficiency calculated by the second calculating means, the pump control means maintains the operating state of the heat collecting pump for a certain period of time. The heat collecting system according to claim 1, wherein the heat collecting system is characterized. A solar heat collector that heats a heat medium with heat obtained by receiving sunlight, a heat storage tank that stores heat based on the heat medium heated by the solar heat collector, and the solar heat collector and the above. In a control method of a heat collection system equipped with a heat collection pump as a power source for circulating a heat medium to and from a heat storage tank.
The first calculation step for calculating the amount of heat collected by the solar heat collector, and
The second calculation step of calculating the heat collection system efficiency obtained by dividing the heat collection amount calculated in the first calculation step by the power consumption of the heat collection pump, and the second calculation step.
A first pump control step for operating the heat collecting pump when the heat collecting system efficiency calculated in the second calculation step is equal to or higher than the first predetermined value.
A second pump control step of stopping the heat collecting pump when the heat collecting system efficiency calculated in the second calculation step is less than the second predetermined value of the first predetermined value or less.
A method of controlling a heat collecting system, which comprises.

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