JP2009275971A - Forced circulation type solar water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a force circulation type solar water heater superior in construction performance and maintenance performance as it has a simple constitution with the small number of components, and capable of adjusting a heat medium circulation amount by selecting the optimum rotational frequency of a DC pump for circulation, increasing a returning temperature of a heat medium by increasing the thermal energy collection corresponding to the change of weather in a short time, having superior heat collecting efficiency and energy saving performance by reduction of power consumption by the DC pump for circulation, surely circulating the heat medium, and improved in stability and certainty in operation. <P>SOLUTION: This forced circulation type solar water heater includes: the DC pump for circulation, disposed on the way of a circulation flow channel for circulating the heat medium; a returning temperature sensor disposed near an inlet of a heat exchanging section of the circulation flow channel for detecting the returning temperature of the heat medium; a hot water storage temperature sensor for detecting a hot water storage temperature in a hot water storage tank; an expansion tank disposed on the way of the circulation flow channel; and a control section for controlling the rotational frequency of the DC pump for circulation so that it has the rotational frequency as high as possible within a range of the determined rotational frequency in such a state that temperature difference between the returning temperature and the hot water storage temperature is a predetermined value or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a forced circulation solar water heater that heats water in a hot water storage tank by circulating a heat medium such as an antifreeze liquid in a circulation channel disposed between the heat collector (panel) and the hot water storage tank. About.

Conventionally, in a forced circulation solar water heater, when a heat exchange part formed in a coil shape in the middle of a circulation channel is sunk in a hot water storage tank and the heat medium is circulated between the heat collector (panel) and the hot water storage tank In addition, the temperature of the heat medium is measured in the vicinity of the heat collector, and the drive and stop of the circulation pump for circulating the heat medium are controlled based on the temperature.
In such a forced circulation solar water heater, in order to measure the temperature of the heat medium, it is necessary to connect the temperature sensor installed near the collector on the roof and the control unit installed on the ground by wiring. However, there is a possibility that wiring mistakes and wiring deterioration over time may occur, and workability and durability were lacking. In addition, when a defect or the like occurs in the temperature sensor, it has to go up to the roof in order to perform maintenance work such as inspection, repair, and replacement, and lacks maintainability.
In order to solve this problem, for example, in Patent Document 1, a heat medium temperature detector that detects the temperature of the heat medium that has passed through the solar heat collector is heated from the solar heat collector to the heat exchanger. Installed near the hot water storage tank in the pipe that sends the medium, and connected to the control device is a heat medium temperature detector and a water temperature detector that detects the temperature of the water in the hot water tank, and is detected by the heat medium temperature detector. A solar heat collecting apparatus is disclosed that controls the operation and stop of the circulation pump based on the temperature difference between the heat medium temperature and the water temperature detected by the water temperature detector.
JP 2004-44952 A

However, the above conventional technique has the following problems.
(1) The solar heat collecting apparatus of (Patent Document 1) has a temperature difference (TH) between the heat medium temperature (TH) detected by the heat medium temperature detector and the water temperature (TL) detected by the water temperature detector. -TL), and continues to operate the circulation pump as long as this temperature difference (TH-TL) is equal to or higher than a certain reference temperature, thereby performing the heat collecting operation of the solar heat collector, and the heat medium temperature (TH) When the temperature difference (TH-TL) from the water temperature (TL) becomes smaller than a certain reference temperature, the circulation pump is stopped. That is, by simply switching between driving and stopping of the circulation pump, the circulation pump is driven with a constant circulation amount regardless of the temperature difference (TH-TL) between the heat medium temperature (TH) and the water temperature (TL). It will be. As the water temperature (TL) rises, the temperature difference (TH-TL) becomes smaller and the water temperature (TL) becomes difficult to rise, but the same circulation as when the temperature difference (TH-TL) is large in such a state. If circulation is continued in an amount, the heat medium is circulated without being able to collect heat sufficiently, which not only lacks the efficiency of heat collection, but also increases the power consumption of the circulation pump, resulting in lack of energy savings. Had.
(2) Further, when the temperature difference (TH-TL) between the heat medium temperature (TH) and the water temperature (TL) becomes smaller than a certain reference temperature, the circulation pump is completely stopped. The heat medium is likely to boil due to solar radiation when the pump is stopped, and the air generated by the boil tends to accumulate in the piping, but air removal is not taken into consideration, so even if the circulation pump is started, the heat medium is sufficient However, there is a problem that the stability and reliability of the operation are lacking.
(3) Furthermore, although the heat medium temperature near the heat collector and the heat medium temperature (TH) near the hot water tank are strictly different, the difference between the heat medium temperature (TH) and the water temperature (TL). If the circulation pump is stopped immediately when the temperature (TH-TL) becomes lower than a certain reference temperature, the heat medium is excessively heated by the heat collector while the circulation pump is stopped. In particular, when the weather changes in a short time, there is a problem that the water temperature (TL) cannot be raised sufficiently and the efficiency of heat collection is insufficient. It was.

  The present invention has been made to solve the above-mentioned problems, and has a simple structure with a small number of parts, excellent workability and maintainability, and the optimum rotation speed of the circulation DC pump is selected to circulate the heat medium. By adjusting, the amount of heat collected can be increased in response to a short-term change in weather. As a result, the return temperature of the heat medium can be increased efficiently without waste, and the efficiency of heat collection is excellent, and the power consumption of the circulating DC pump can be reduced, and not only is it excellent in energy saving. It is an object of the present invention to provide a forced circulation solar water heater that can reliably circulate a heat medium and is excellent in operational stability and reliability.

In order to solve the above problems, the forced circulation solar water heater of the present invention has the following configuration.
The forced circulation solar water heater according to claim 1 has a circulation channel for circulating a heat medium between a heat collector and a heat exchange part set in the hot water storage tank, and the inside of the hot water storage tank. A forced circulation solar water heater that heats the water in the circulation channel, and is arranged in the middle of the circulation channel, and circulates the heat medium, and in the vicinity of the inlet of the heat exchange part of the circulation channel A return temperature sensor that detects a return temperature of the heat medium, a hot water storage temperature sensor that detects a hot water storage temperature in the hot water storage tank, an expansion tank disposed in the middle of the circulation flow path, and the return temperature The circulation DC so that the temperature difference between the return temperature detected by the sensor and the hot water storage temperature detected by the hot water storage temperature sensor is not less than a preset value and is as high as possible within a set rotational speed range. Control that controls the rotation speed of the pump It has a configuration and a and.
This configuration has the following effects.
(1) The temperature difference between the return temperature of the heat medium near the inlet of the heat exchange unit detected by the return temperature sensor and the hot water temperature in the hot water storage tank detected by the hot water temperature sensor is greater than or equal to a preset value. By having a control unit that controls the rotational speed of the circulating DC pump so that the rotational speed is as high as possible within the range of the rotational speed, the temperature difference between the return temperature and the hot water storage temperature can be larger than a preset value. For example, the rotational speed of the circulating DC pump is increased, and if the rotational speed is smaller than a preset value, the rotational speed of the circulating DC pump is decreased, and the heat medium is circulated with the optimum circulation amount, and the return temperature and the hot water storage temperature are Since the temperature difference can be set to a predetermined value or more, heat collection and heat exchange by the heat medium can be efficiently performed without waste. In particular, when the temperature difference between the return temperature and the hot water storage temperature is small, the temperature of the heat medium can be maintained in an appropriate range for heat exchange by reducing the circulation rate of the heat medium, so the efficiency of heat collection In addition, the rotational speed of the circulating DC pump can be suppressed to reduce power consumption, and energy saving is excellent.
(2) Since the return temperature sensor is disposed in the vicinity of the inlet of the heat exchange section of the circulation channel, the temperature of the heat medium immediately before the start of heat exchange can be accurately detected. Circulation rate of the heat medium in consideration of the time required for heat exchange between the heat medium and the water in the hot water storage tank (hot water) (Flow velocity) can be kept optimal, and the collected heat can be used efficiently without waste, and the drive efficiency and energy saving are excellent.
(3) By using a circulation DC pump, the rotational speed can be changed smoothly by simply controlling the voltage, PWM (pulse width modulation), etc., and the heat medium is circulated simply and reliably with the optimum circulation amount. It is easy to control and easy to handle.

Here, the control unit calculates a temperature difference between the return temperature detected by the return temperature sensor and the hot water storage temperature detected by the hot water storage temperature sensor, and controls the rotational speed of the circulating DC pump based on the calculated temperature difference. Has a computer.
The control unit can maintain an appropriate temperature for heat exchange by controlling the number of rotations of the circulating DC pump so that the temperature difference between the return temperature and the hot water storage temperature is equal to or greater than a preset value. In other words, if the temperature difference between the return temperature and the hot water storage temperature is equal to or greater than a preset value, a sufficient amount of heat is collected by the heat medium, so the rotational speed of the circulating DC pump is increased and the rotation speed is as high as possible. The heat exchange amount is increased by increasing the circulation amount of the heat medium, and if the temperature difference between the return temperature and the hot water storage temperature is smaller than a preset value, the circulation DC pump By reducing the number of rotations and reducing the circulation amount of the heat medium, the return temperature is increased by extending the heat collection time so that the temperature difference between the return temperature and the hot water storage temperature is increased.
As the heat medium, antifreeze is preferably used. This is because the heat medium can be prevented from freezing in winter or in a cold region, and the circulation channel, the circulation DC pump, etc. can be prevented from being damaged, and the reliability is excellent.
By providing an air layer in the expansion tank, it is possible to absorb changes in the volume of the heat medium, and to effectively prevent damage to the circulation flow path and the circulation DC pump. In addition, the heat medium can be easily replaced, and the maintenance is excellent. The expansion tank may be an open air type or a semi-sealed type.

Invention of Claim 2 is a forced circulation type solar water heater of Claim 1, Comprising: The said control part carries out the said DC pump for circulation at the time of the first start-up of the said DC pump for circulation of the day Each time it is activated a number of times, the DC pump for circulation is driven at a higher rotational speed than the rotational speed during the heat collecting operation.
With this configuration, in addition to the operation of the first aspect, the following operation is provided.
(1) When the circulating DC pump is started for the first time on the day, the circulating flow path generated while the circulating DC pump has not been used for a long time by driving at a higher rotational speed than the rotational speed during the heat collecting operation. The air inside can be forcibly discharged, the heat medium can be circulated reliably, and the operation is stable and reliable.
(2) Even when the circulation DC pump is stopped, the temperature of the heat medium suddenly rises in a short time due to sudden solar radiation, etc., and the heat medium boils and air is generated. By driving at a rotational speed higher than the rotational speed at the time of heat collection operation every time it is started, the heat medium can be reliably circulated while forcibly discharging the air in the circulation flow path. Excellent operational stability and reliability.
(3) Because the circulating DC pump is periodically driven at a higher rotational speed than the rotational speed during the heat collecting operation every time the circulating DC pump is activated for the first time or every time the circulating DC pump is activated a predetermined number of times. There is no need to detect the flow rate of the heat medium using a flow meter or the like, or to determine the presence or absence of air based on the flow rate, the number of parts can be reduced, control is easy, and the usability is excellent.

Here, since the expansion tank is disposed in the middle of the circulation flow path, the air in the circulation flow path can be recovered and removed by the expansion tank only by circulating the heat medium with the circulation DC pump.
The rotational speed of the circulating DC pump during air venting should be selected as appropriate according to the characteristics of the circulating DC pump, the length of the circulating flow path, the stop (rest) time of the circulating DC pump, and the like. Can do. If driven at the maximum number of revolutions, air can be vented more reliably, but by driving at the minimum number of revolutions, the power required for driving can be reduced, resulting in excellent energy savings, It is not necessary to circulate the heat medium more than necessary, and a decrease in heat collection efficiency can be prevented.

Invention of Claim 3 is a forced circulation type solar water heater of Claim 1 or 2, Comprising: The said control part is the said DC for circulation after predetermined time progress from the stop of the said DC pump for circulation last time. It has the structure which restarts a pump.
With this configuration, in addition to the operation of the first or second aspect, the following operation is provided.
(1) By restarting the circulation DC pump after a lapse of a predetermined time from the previous stoppage of the circulation DC pump, the return temperature is periodically detected and the temperature of the heat medium (heat collector heating state) is grasped. Therefore, the collected heat can be effectively used without waste, the hot water storage temperature can be raised, and the efficiency of heat collection is excellent.

  Here, if the temperature difference between the return temperature and the hot water storage temperature does not exceed the preset temperature difference even after the circulation DC pump is driven for a certain time, the circulation DC pump is stopped to collect heat. As a result, the power consumption of the circulating DC pump can be reduced, and it is excellent in energy saving and heat collection efficiency.

Invention of Claim 4 is a forced circulation type solar water heater of any one of Claim 1 thru | or 3, Comprising: The said control part is a temperature difference of the said return temperature and the said hot water storage temperature. When the temperature becomes smaller than a set value, the temperature difference between the return temperature and the hot water storage temperature is monitored for a predetermined time, and the temperature difference does not exceed a preset temperature difference even if the predetermined time elapses. After confirming the above, the circulation DC pump is stopped.
With this configuration, in addition to the operation of any one of claims 1 to 3, the following operation is provided.
(1) When the temperature difference between the return temperature and the hot water storage temperature becomes smaller than the set value, the temperature difference between the return temperature and the hot water storage temperature is monitored for a predetermined time. Stopping the circulation DC pump after confirming that the temperature difference does not exceed the set temperature difference allows the number of revolutions to be controlled based on the temperature of the heat medium in the vicinity of the collector, and in the vicinity of the actual collector Even if there is a temperature difference between the temperature of the heat transfer medium and the return temperature, it will not be affected, and even if the weather changes in a short time, the accurate heat collection state of the heat collector can be grasped Heat can be collected efficiently without waste, the circulation DC pump is not wastefully driven, and heat collection efficiency and energy saving are excellent.

Here, while the temperature difference between the return temperature and the hot water storage temperature is monitored for a predetermined period of time, if the temperature difference is greater than or equal to a preset temperature difference, the rotational speed is an appropriate temperature difference for heat exchange. Heat can be collected efficiently by driving the circulation DC pump and circulating the heat medium.
The time for monitoring the temperature difference between the return temperature and the hot water storage temperature is preferably set equal to or longer than the time required for the heat medium to move from the outlet of the heat collector to the position of the return temperature sensor. The temperature difference from the hot water storage temperature can be obtained using the temperature of the heat medium in the heat collector as the return temperature, and even if the weather changes in a short time, there is no waste based on the exact heat collection state of the heat collector This is because efficient operation can be realized.

According to invention of Claim 1, it has the following effects.
(1) The number of rotations of the circulating DC pump corresponding to the temperature difference between the return temperature of the heat medium near the inlet of the heat exchanger detected by the return temperature sensor and the hot water storage temperature in the hot water storage tank detected by the hot water temperature sensor By selecting the control unit, it is possible to circulate the heat medium with an optimal circulation amount and perform heat collection and heat exchange without waste, especially when the temperature difference between the return temperature and the hot water storage temperature is small. By reducing the rotational speed of the DC pump for use and reducing the circulation rate of the heat medium and increasing the amount of heat collection, the return temperature can be increased efficiently, and the efficiency of heat collection is excellent. Therefore, it is possible to provide a forced circulation solar water heater with low power consumption and excellent energy saving.

According to invention of Claim 2, in addition to the effect of Claim 1, it has the following effects.
(1) Circulation by driving the circulation DC pump at a rotational speed higher than the rotational speed at the time of the heat collecting operation at the first activation of the circulation DC pump on the day or whenever the circulation DC pump is activated a predetermined number of times. It is possible to provide a forced circulation type solar water heater excellent in stability and reliability of operation capable of forcibly discharging the air in the flow path and reliably circulating the heat medium.

According to invention of Claim 3, in addition to the effect of Claim 1 or 2, it has the following effects.
(1) By restarting the circulation DC pump after a lapse of a predetermined time from the previous stoppage of the circulation DC pump, the return temperature is periodically detected and the temperature of the heat medium (heat collector heating state) is grasped. Therefore, it is possible to provide a forced circulation solar water heater excellent in the efficiency of heat collection that can effectively use the collected heat without waste.

According to invention of Claim 4, in addition to the effect of any one of Claims 1 thru | or 3, it has the following effects.
(1) When the temperature difference between the return temperature and the hot water storage temperature becomes smaller than the set value, the temperature difference between the return temperature and the hot water storage temperature is monitored for a predetermined time, whereby the temperature of the heat medium near the actual heat collector is monitored. Even if there is a temperature difference between the return temperature and the return temperature, the number of revolutions can be controlled based on the temperature of the heat medium near the heat collector without being affected, and the weather changes in a short time. In addition, the accurate heat collection state of the heat collector can be grasped and heat can be collected efficiently without waste, and the temperature difference between the return temperature and the hot water storage temperature is preset even after a predetermined time has elapsed. A forced circulation solar water heater with excellent heat collection efficiency and energy saving that can prevent wasteful driving of the circulation DC pump by stopping the circulation DC pump after confirming that the temperature difference does not exceed the temperature difference Can be provided.

Hereinafter, the forced circulation solar water heater in Embodiment 1 of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic diagram showing the configuration of the forced circulation solar water heater according to the first embodiment.
In FIG. 1, 1 is the forced circulation solar water heater of the first embodiment, 2 is the two heat collectors of the forced circulation solar water heater 1 installed on the roof or the like, and 3 is the forced circulation in which tap water is stored. The hot water storage tank 4 of the solar water heater 1, 4 is a circulation channel of the forced circulation solar water heater 1 for circulating the heat medium between the heat collector 2 and the hot water storage tank 3, 4 a is in the middle of the circulation channel 4. A heat exchanging part 4b formed in a coil shape and set in the hot water storage tank 3 is a delivery pipe 4b for the circulation flow path 4 connecting the outlet of the heat exchanging part 4a and one of the heat collectors 2, 4c has two A connection pipe of the circulation flow path 4 connecting the heat collectors 2, 4 d is a return pipe of the circulation flow path 4 connecting the other heat collector 2 and the inlet of the heat exchanging part 4 a, 5 is a circulation flow An expansion tank disposed in the middle of the path 4, a circulation DC pump 6 disposed in the middle of the circulation flow path 4 for circulating the heat medium, and 7 a circulation A return temperature sensor that is disposed near the inlet of the heat exchange section 4a of the path 4 and detects the return temperature of the heat medium, 8 is a hot water storage temperature sensor that detects the hot water storage temperature in the hot water storage tank 3, and 10 is a forced circulation solar water heater 1 is a control unit provided with a microcomputer for controlling the whole.

Antifreeze was used as the heat medium circulating in the circulation channel 4. This is because freezing in winter or in a cold region can be prevented, damage to the circulation flow path 4 and the circulation DC pump 6 can be prevented, and the reliability is excellent.
By disposing the expansion tank 5 in the middle of the circulation flow path 4, the air in the circulation flow path 4 can be collected and discharged by the expansion tank 5 only by circulating the heat medium by the circulation DC pump 6. it can. Further, the expansion tank 5 absorbed the volume change of the heat medium, and the circulation channel 4 and the circulation DC pump 6 were prevented from being damaged.
When the hot water storage tank 3 is vertically long, a plurality of hot water storage temperature sensors 8 are preferably provided in the vertical direction of the hot water storage tank 3. This is because the average hot water storage temperature in the hot water storage tank 3 is accurately detected.

The control unit 10 calculates a temperature difference between the return temperature detected by the return temperature sensor 7 and the hot water storage temperature detected by the hot water storage temperature sensor 8, and controls the rotational speed of the circulating DC pump 6 based on the calculated value. Has a microcomputer. In addition, the range of the rotation speed of the circulating DC pump 6 during the heat collecting operation is set in advance.
The control unit 10 can maintain an appropriate temperature for heat exchange by controlling the number of rotations of the circulation DC pump 6 so that the temperature difference between the return temperature and the hot water storage temperature is equal to or greater than a preset value. If the temperature difference between the return temperature and the hot water storage temperature is equal to or greater than a preset value, a sufficient amount of heat is collected by the heat medium. Therefore, the rotational speed of the circulating DC pump 6 is increased and the rotational speed is as high as possible. The amount of heat exchange is increased by increasing the circulation amount of the heat medium, and if the temperature difference between the return temperature and the hot water storage temperature is smaller than a preset value, the circulation DC pump 6 By reducing the number of rotations and reducing the circulation amount of the heat medium, the return temperature is increased by extending the heat collection time so that the temperature difference between the return temperature and the hot water storage temperature is increased. Thereby, heat collection and heat exchange can be performed efficiently without waste.

  In the present embodiment, the expansion tank 5 and the circulating DC pump 6 are arranged in the middle of the delivery pipe 4b. However, their mounting positions can be arbitrarily selected, and in the middle of the delivery pipe 4b or the return pipe 4d. It can be anywhere.

The operation of the forced circulation solar water heater according to Embodiment 1 configured as described above will be described with reference to the drawings.
FIG. 2 is a flowchart showing the operation of the forced circulation solar water heater of the first embodiment, and FIG. 3 is a diagram showing changes in the number of rotations of the circulation DC pump in each step of FIG.
In FIG. 2, when the operation of the forced circulation solar water heater 1 is started, the control unit 10 recognizes that the circulation DC pump 6 is started for the first time on the day, and turns on the circulation DC pump 6 at a high rotational speed. Drive (S1). In the present embodiment, as shown in FIG. 3, the circulating DC pump 6 is driven at a higher rotational speed than the maximum rotational speed during the heat collecting operation for a fixed time t ₁ .
Next, in FIG. 2, the control unit 10 determines the return temperature T _H (t) of the heat medium at the time t detected by the return temperature sensor 7 and the hot water storage temperature T _L at the time t detected by the hot water storage temperature sensor 8. A temperature difference ΔT (= T _H (t) −T _L (t)) with respect to (t) is calculated (S2).
Then, the control unit 10 determines whether the temperature difference above T ₁ to the temperature difference ΔT is preset (S3).
If the temperature difference ΔT is equal to or greater than the preset temperature difference T ₁ , the rotational speed of the circulating DC pump 6 corresponding to the temperature difference ΔT is selected (S4), and the process returns to step 2.
The controller 10 repeats Step 2 to Step 4 every time the predetermined time Δt elapses, and continues to drive the circulating DC pump 6 at a rotational speed corresponding to the temperature difference ΔT. Thereby, as shown in FIG. 3, the rotation speed of DC pump 6 for circulation changes according to temperature difference (DELTA) T.

In step 3 of FIG. 2, when the temperature difference ΔT becomes smaller than the preset temperature difference T ₁ , the process proceeds from step 3 to step 5.
The control unit 10 obtains a temperature difference ΔT between the return temperature T _H (t) and the hot water storage temperature T _L (t) at the time t at every elapse of the predetermined time Δt, and whether the temperature difference is equal to or greater than a preset temperature difference T _1. Is determined (S6).
When the temperature difference ΔT is smaller than the preset temperature difference T ₁ , the circulation DC pump 6 is continuously driven and step 6 is repeated until a predetermined time t ₁ has elapsed (S7). At this time, as shown in FIG. 3, the circulation DC pump 6 is driven at the minimum number of rotations, whereby the circulation amount of the heat medium can be suppressed and the power consumption of the circulation DC pump can be reduced.
If the temperature difference ΔT is smaller than the temperature difference T ₁ even after the fixed time t ₁ has elapsed, the controller 10 stops driving the circulating DC pump 6 as shown in FIGS. 2 and 3 (S8). .
The fixed time t ₁ is preferably set equal to or longer than the time required for the heat medium to move from the outlet of the heat collector 2 to the position of the return temperature sensor 7. The temperature difference from the hot water storage temperature can be obtained using the temperature of the heat medium in the heat collector 2 as a return temperature, and even if the weather changes in a short time, it is wasted based on the exact heat collection state of the heat collector 2 This is because it is possible to realize an efficient operation without any trouble.
Further, in step 6, the temperature difference ΔT at time t is in the case of the temperature difference above T _1, as shown in FIG. 2, the process proceeds from step 6 to step 2.

Step 8 is completed, as shown in FIG. 2, after stopping of the circulation DC pump 6 counts the time until the stop time t ₂ set in advance has elapsed (S9). During this time, as shown in FIG. 3, the circulating DC pump 6 remains stopped.
When the stop time t ₂ elapses, the circulating DC pump 6 is restarted. As shown in FIG. 2, every time the circulating DC pump 6 is started a predetermined number of times (for example, i = 5 in the case of FIG. 2). Returning to step 1, the circulating DC pump 6 is driven at a higher rotational speed than the maximum rotational speed during the heat collecting operation. Otherwise (i = 2 to 4), the process returns to step 2. In FIG. 3, since the number of times i of the circulation DC pump 6 is driven i = 3 at the end of step 9, the process returns to step 2 and the temperature difference between the return temperature T _H (t) and the hot water storage temperature T _L (t). ΔT is obtained, and the circulating DC pump 6 is driven at a rotational speed corresponding to the temperature difference ΔT.

As described above, the forced circulation solar water heater according to Embodiment 1 has the following effects.
(1) The temperature difference between the return temperature of the heat medium near the inlet of the heat exchange unit detected by the return temperature sensor and the hot water temperature in the hot water storage tank detected by the hot water temperature sensor is greater than or equal to a preset value. By having a control unit that controls the rotational speed of the circulating DC pump so that the rotational speed is as high as possible within the range of the rotational speed, the temperature difference between the return temperature and the hot water storage temperature can be larger than a preset value. For example, the rotational speed of the circulating DC pump is increased, and if the rotational speed is smaller than a preset value, the rotational speed of the circulating DC pump is decreased, and the heat medium is circulated with the optimum circulation amount, and the return temperature and the hot water storage temperature are Since the temperature difference can be set to a predetermined value or more, heat collection and heat exchange by the heat medium can be efficiently performed without waste. In particular, when the temperature difference between the return temperature and the hot water storage temperature is small, the amount of heat collected can be increased by reducing the circulation rate of the heat medium. The temperature can be raised, the efficiency of heat collection is excellent, and the power consumption can be reduced by suppressing the number of rotations of the circulating DC pump, resulting in excellent energy saving.
(2) Since the return temperature sensor is disposed in the vicinity of the inlet of the heat exchange section of the circulation channel, the temperature of the heat medium immediately before the start of heat exchange can be accurately detected. Circulation rate of the heat medium in consideration of the time required for heat exchange between the heat medium and the water in the hot water storage tank (hot water) (Flow velocity) can be kept optimal, and the collected heat can be used efficiently without waste, and the drive efficiency and energy saving are excellent.
(3) Since the expansion tank is arranged in the middle of the circulation channel, the expansion and contraction of the heat medium can be absorbed to prevent damage to the circulation channel and the circulation DC pump, etc. Excellent.
(4) By using a circulation DC pump, the rotational speed can be changed smoothly by simply controlling the voltage, and the heat medium can be circulated simply and surely with the optimum circulation amount, which is easy to control. Excellent handleability.
(5) When the circulation DC pump is started for the first time on the day, the circulation flow path generated while the circulation DC pump is not used for a long time by driving at a higher rotation speed than the rotation speed during the heat collecting operation. The air inside can be forcibly extracted, the heat medium can be circulated reliably, and the operation is stable and reliable.
(6) Even when the circulating DC pump is stopped, the temperature of the heat medium suddenly rises in a short time due to sudden solar radiation, etc., and the heat medium boils and air is generated. By driving at a rotational speed higher than the rotational speed at the time of heat collection operation every time it is started, the heat medium can be reliably circulated while forcibly discharging the air in the circulation flow path. Excellent operational stability and reliability.
(7) Because the circulation DC pump is periodically driven at a higher rotational speed than the rotational speed during the heat collecting operation at the first activation of the circulation DC pump on the day or every time the circulation DC pump is activated a predetermined number of times. There is no need to detect the flow rate of the heat medium using a flow meter or the like, or to determine the presence or absence of air based on the flow rate, the number of parts can be reduced, control is easy, and the usability is excellent.
(8) By restarting the circulation DC pump after a lapse of a predetermined time from the previous stoppage of the circulation DC pump, the return temperature is detected periodically to determine the temperature of the heat medium (heat collector heating state). Therefore, the collected heat can be effectively used without waste, the hot water storage temperature can be raised in a short time, and the efficiency of heat collection is excellent.
(9) When the temperature difference between the return temperature and the hot water temperature becomes smaller than the set value, the temperature difference between the return temperature and the hot water temperature is monitored for a predetermined time. Stopping the circulation DC pump after confirming that the temperature difference does not exceed the set temperature difference allows the number of revolutions to be controlled based on the temperature of the heat medium in the vicinity of the collector, and in the vicinity of the actual collector Even if there is a temperature difference between the temperature of the heat transfer medium and the return temperature, it will not be affected, and even if the weather changes in a short time, the accurate heat collection state of the heat collector can be grasped Heat can be collected efficiently without waste, the circulation DC pump is not wastefully driven, and heat collection efficiency and energy saving are excellent.

  The present invention has a simple configuration with a small number of parts, excellent workability and maintainability, and by selecting the optimum number of rotations of the circulation DC pump and adjusting the circulation amount of the heat medium, the weather changes in a short time. The amount of heat collected can be increased in response to this, so the return temperature of the heat medium can be increased efficiently without waste, and the efficiency of heat collection is excellent, and the power consumption of the circulating DC pump is reduced. In addition to being excellent in energy saving, it is possible to circulate the heat medium reliably and contribute to environmental problems by widely disseminating forced circulation solar water heaters with excellent operational stability and reliability. be able to.

The schematic diagram which shows the structure of the forced circulation type solar water heater of Embodiment 1. The flowchart which shows operation | movement of the forced circulation type solar water heater of Embodiment 1. The figure which shows the change of the rotation speed of the DC pump for circulation in each step of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Forced circulation type solar water heater 2 Heat collector 3 Hot water storage tank 4 Circulation flow path 4a Heat exchange part 4b Delivery pipe 4c Connection pipe 4d Return pipe 5 Expansion tank 6 Circulation DC pump 7 Return temperature sensor 8 Hot water storage temperature sensor 10 Control part

Claims (4)

A forced circulation solar water heater having a circulation flow path for circulating a heat medium between a heat collector and a heat exchange section set in the hot water storage tank, and heating water in the hot water storage tank. ,
A circulation DC pump disposed in the middle of the circulation flow path for circulating the heat medium, and a return temperature sensor disposed near the inlet of the heat exchange section of the circulation flow path for detecting the return temperature of the heat medium. And a hot water storage temperature sensor for detecting the hot water storage temperature in the hot water storage tank, an expansion tank disposed in the middle of the circulation channel, the return temperature detected by the return temperature sensor and the hot water storage temperature sensor. A controller that controls the rotational speed of the circulating DC pump so that the temperature difference from the hot water storage temperature is not less than a preset value and is as high as possible within the set rotational speed range. A forced circulation solar water heater. The controller is configured to rotate the circulating DC pump at a rotational speed higher than the rotational speed during the heat collecting operation when the circulating DC pump is started for the first time or every time the circulating DC pump is started a predetermined number of times. The forced circulation solar water heater according to claim 1, wherein the forced circulation solar water heater is driven. 3. The forced circulation solar water heater according to claim 1, wherein the control unit restarts the circulation DC pump after a predetermined time has elapsed since the previous stop of the circulation DC pump. The control unit monitors a temperature difference between the return temperature and the hot water storage temperature for a predetermined time when a temperature difference between the return temperature and the hot water storage temperature becomes smaller than a set value, and the predetermined time has elapsed. However, the said DC difference is stopped after confirming that the said temperature difference does not become more than the preset temperature difference, The compulsion according to any one of claims 1 to 3 Circulating solar water heater.

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