JP2012163253A - Solar heat utilization water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar heat utilization water heater that utilizes solar energy with high efficiency to generate power and supply hot water, and has superior reliability.SOLUTION: The solar heat utilization water heater includes: a hot water storage tank 1; a photovoltaic power generation panel 4; a panel cooling apparatus 3 that cools the photovoltaic power generation panel 4; a circulation circuit having an outgoing channel 10 that sends water taken out from the inside of the hot water storage tank 1 to the panel cooling apparatus 3 and return channels 11, 12 that return hot water generated by the water receiving heat of the photovoltaic power generation panel 4 to the hot water storage tank 1; a bypass channel 13 that pours some of hot water flowing out from the panel cooling apparatus 3 into the outgoing channel 10; an inflow water temperature detection device 6a for detecting a temperature of water flowing into the panel cooling apparatus 3; a dew-point temperature obtaining device for obtaining a dew-point temperature of outside air; and a flow rate adjust device for adjusting a flow rate of hot water flowing in the bypass channel 13 so that an inflow water temperature detected by the inflow water temperature detection device 6a reaches the dew-point temperature or higher.

Description

  The present invention relates to a solar water heater.

  Patent Document 1 below discloses a solar heat pump system in which an apparatus for cooling a photovoltaic power generation panel is configured as an evaporator of a refrigeration cycle, a solar pump is used as a heat source to drive a heat pump, and heat is supplied from a condenser in the refrigeration cycle. Has been. In this system, the evaporation temperature of the evaporator is controlled to 40 to 60 ° C., condensation on the photovoltaic power generation panel is suppressed, and the reliability of the photovoltaic power generation panel is ensured.

JP 2008-155743 A

  When the heat of the photovoltaic power generation panel is recovered by the heat pump as in the invention of Patent Document 1, power consumption of the compressor that drives the heat pump is generated. Therefore, when the heat source temperature of the solar power generation panel is high and water can be directly heated by the solar power generation panel, extra power consumption is generated, and the operation efficiency of the apparatus is reduced. In addition, when trying to obtain a larger amount of heat from the photovoltaic power generation panel, the temperature of the cooling medium that cools the photovoltaic power generation panel is desirably as low as possible. However, in the invention of Patent Document 1, in order to drive the heat pump, The operation of the heat pump is lowered when the evaporation temperature is lowered and an attempt is made to obtain a large amount of heat. For this reason, more power consumption is required, and there is a problem that the operation efficiency of the apparatus further decreases.

  The present invention has been made to solve the above-described problems, and provides a solar water heater that can generate power and hot water using solar energy with high efficiency and has excellent reliability. For the purpose.

  The hot water supply apparatus using solar heat according to the present invention includes a hot water storage tank for storing hot water supplied to the load side, a solar power generation panel, a panel cooling device for cooling the solar power generation panel, and panel cooling for water taken out from the hot water storage tank. A circulation circuit having a forward flow path to be sent to the apparatus, a return flow path for returning hot water generated by the water receiving the heat of the photovoltaic power generation panel to the hot water storage tank, and part of the hot water flowing out from the panel cooling device Detected by a bypass flow path that can be injected into the forward flow path, an incoming water temperature detection means that detects the temperature of the water flowing into the panel cooling device, a dew point temperature acquisition means that acquires the dew point temperature of the outside air, and an incoming water temperature detection means Flow rate adjusting means for adjusting the flow rate of hot water flowing through the bypass channel so that the incoming water temperature is equal to or higher than the dew point temperature acquired by the dew point temperature acquiring means.

  According to the present invention, hot water can be generated by directly using the heat of the photovoltaic power generation panel. For this reason, unlike the case where a heat pump is interposed, since the power consumption of a compressor does not generate | occur | produce, the energy efficiency as a whole can be improved. Moreover, since the temperature of the water supplied to a panel cooling device can be made more than the dew point temperature of external air, it can prevent reliably that dew condensation arises in a photovoltaic power generation panel. For this reason, it is possible to reliably prevent a decrease in insulation of the photovoltaic power generation panel due to condensation and a decrease in long-term reliability due to material deterioration. Furthermore, since the power generation efficiency of the photovoltaic power generation panel increases as the panel temperature decreases, the amount of power generated by the photovoltaic power generation panel can be increased by lowering the temperature of the photovoltaic power generation panel by cooling with the panel cooling device. Can do. For these reasons, according to the present invention, solar energy can be used with high efficiency to generate power and hot water, and the reliability of the apparatus can be improved.

It is a block diagram which shows the solar-powered hot water supply apparatus of Embodiment 1 of this invention. It is a flowchart of the routine performed in order that the control apparatus may control the opening degree of a three-way valve in Embodiment 1 of this invention. It is a block diagram which shows the solar-heating hot water supply apparatus of Embodiment 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram illustrating a solar water heater using Embodiment 1 of the present invention. As shown in FIG. 1, a solar water heater (hereinafter simply referred to as “hot water heater”) of the present embodiment includes a hot water storage tank 1, a pump 2, a panel cooling device 3, a photovoltaic power generation panel 4, And a three-way valve 5. The panel cooling device 3 is disposed so as to be in contact with the back surface of the photovoltaic power generation panel 4, and can remove heat from the photovoltaic power generation panel 4 that is at a high temperature during power generation to cool the photovoltaic power generation panel 4.

  A lower passage of the hot water storage tank 1 and the inlet of the panel cooling device 3 are connected by an outward flow path 10. A pump 2 for supplying water is provided in the middle of the forward flow path 10. A return flow path 11 is connected between the outlet of the panel cooling device 3 and the three-way valve 5. The three-way valve 5 and the upper part of the hot water storage tank 1 are connected by a return flow path 12. Further, a bypass flow path 13 connects between the three-way valve 5 and the forward flow path 10 on the upstream side of the pump 2.

  The hot water storage tank 1 stores hot water while forming temperature stratification, and can store hot water on the upper side and low temperature water on the lower side so as not to be mixed. A water supply end A for supplying water from a water source such as a water supply is connected to the lower part of the hot water storage tank 1 via a water supply channel 14. The upper part of the hot water storage tank 1 and the hot water outlet end B are connected via a hot water supply channel 15. When the hot water stored in the upper part of the hot water storage tank 1 is discharged to the hot water outlet B through the hot water supply passage 15 in accordance with the demand on the load side, at the same time, the hot water stored in the upper part of the hot water storage tank 1 passes through the water supply passage 14. The sent water flows into the lower part of the hot water storage tank 1.

  When the pump 2 is operated, water is taken out from the lower part of the hot water storage tank 1, and the taken out water flows into the panel cooling device 3 through the forward flow path 10. The solar power generation panel 4 is heated by receiving light at the time of power generation, and becomes high temperature (for example, about 70 ° C.). As the heat of the photovoltaic power generation panel 4 is transferred to the water passing through the panel cooling device 3, the temperature of the water rises. In the present specification, for convenience, water heated by the panel cooling device 3 and having a raised temperature is referred to as “hot water”. This hot water flows out of the panel cooling device 3, passes through the return flow path 11, the three-way valve 5, and the return flow path 12 and flows into the upper part of the hot water storage tank 1 and stored. The photovoltaic power generation panel 4 is cooled by removing heat from the water passing through the panel cooling device 3.

  The three-way valve 5 can branch a part of the hot water flowing out from the panel cooling device 3 into the bypass flow path 13. The three-way valve 5 has a configuration in which the valve opening degree of each flow path can be continuously changed, and the ratio of the flow rate of hot water flowing to the return flow path 12 and the flow rate of hot water flowing to the bypass flow path 13 is continuous. Can be changed. The hot water branched by the three-way valve 5 passes through the bypass flow path 13 and joins with the water flowing through the upstream flow path 10 of the pump 2. With such a configuration, the temperature of the water supplied from the pump 2 to the panel cooling device 3 rises according to the amount of hot water joining from the bypass channel 13. That is, the temperature of the water supplied to the panel cooling device 3 increases as the flow rate of hot water flowing through the bypass flow path 13 increases.

  The hot water supply apparatus of this embodiment includes a temperature sensor 6a (incoming water temperature detecting means) that detects the temperature of water supplied to the panel cooling device 3, a temperature sensor 6b (outside air temperature detecting means) that detects the outside air temperature, and a panel. A temperature sensor 6c (return temperature detection means) for detecting the temperature of hot water flowing out of the cooling device 3 and flowing into the hot water storage tank 1 and a temperature sensor 6d (hot water storage temperature detection means) for detecting the temperature of hot water remaining in the upper part of the hot water storage tank 1 ) And a control device 7. The control device 7 controls the opening degree of the three-way valve 5 based on information detected by the temperature sensors 6a to 6d.

  FIG. 2 is a flowchart of a routine executed by the control device 7 to control the opening degree of the three-way valve 5. The control device 7 repeatedly executes this routine every predetermined time. According to this routine, first, the outside air temperature is measured by the temperature sensor 6b (step S1). Subsequently, based on the measured outside air temperature, the dew point temperature of the outside air (hereinafter, simply referred to as “dew point temperature”) is calculated (step S2). The calculation of the dew point temperature requires information on the humidity. In the present embodiment, the humidity is assumed to be an environment where the fluctuation of the humidity is small, and the humidity is set to a fixed value set in advance.

  Subsequently, the dew point temperature Td calculated in step S2 and the temperature of water flowing into the panel cooling device 3 detected by the temperature sensor 6a (hereinafter sometimes referred to as “panel incoming temperature”) Tw. Are compared (step S3). As a result of the comparison, when the panel incoming water temperature Tw is lower than the dew point temperature Td, the opening of the three-way valve 5 is opened to the bypass flow passage 13 side so that the flow rate of hot water flowing through the bypass flow passage 13 increases. Correction is made in the direction of increasing the opening (step S4). When the panel incoming temperature Tw is higher than the dew point temperature Td and the temperature difference between the two is larger than the predetermined temperature difference ΔT, the three-way valve 5 is opened so that the flow rate of hot water flowing through the bypass passage 13 decreases. The degree is corrected so that the opening degree opening to the bypass flow path 13 side becomes smaller. On the other hand, when the panel incoming temperature Tw is higher than the dew point temperature Td and the temperature difference between them is equal to or smaller than the predetermined temperature difference ΔT (that is, when Td ≦ Tw ≦ Td + ΔT), the opening degree of the three-way valve 5 is set to the current value. (Step S6). The predetermined temperature difference ΔT is set to about 3 to 5 ° C., for example.

  By performing the above operation, according to the hot water supply apparatus, the following effects can be obtained. First, hot water can be generated by directly using the heat of the photovoltaic power generation panel 4. For this reason, unlike the case where a heat pump is interposed, a compressor is not required. Therefore, since the power consumption of the compressor does not occur, the overall energy efficiency can be improved.

  Moreover, the temperature of the water supplied to the panel cooling device 3 can be set to be equal to or higher than the dew point temperature of the outside air. Therefore, it is possible to reliably prevent condensation on the photovoltaic power generation panel 4. When dew condensation occurs on the surface of the photovoltaic power generation panel 4, there is a concern that long-term reliability may decrease due to a decrease in insulation or material deterioration. Therefore, by reliably preventing condensation, these reliability problems can be avoided and the reliability can be improved.

  Furthermore, the photovoltaic power generation panel 4 has a characteristic that the power generation efficiency increases as the panel temperature decreases. According to the present hot water supply device, the temperature of the photovoltaic power generation panel 4 can be lowered by the cooling by the panel cooling device 3, so that the amount of power generation in the photovoltaic power generation panel 4 can be increased. Therefore, the energy efficiency as a whole can be further increased.

  In particular, in the above operation, the temperature of the water supplied to the panel cooling device 3 can be maintained between the dew point temperature and a temperature higher than the dew point temperature by ΔT. For this reason, the temperature of the water supplied to the panel cooling device 3 can be kept as low as possible within a range that does not cause condensation on the photovoltaic power generation panel 4. In the panel cooling device 3, heat exchange is performed between the photovoltaic power generation panel 4 and water, and the photovoltaic power generation panel 4 is cooled and the water is heated. The larger the difference, the more it can be increased. Therefore, according to said driving | operation operation | movement, the heat exchange amount as much as possible can be obtained in the range which does not produce dew condensation on the photovoltaic power generation panel 4, and the operating efficiency as a hot water supply apparatus can be improved. Moreover, since the temperature of the photovoltaic power generation panel 4 can be further reduced, the power generation efficiency can be further improved.

  In the present embodiment, the humidity is a fixed value set in advance, and the dew point temperature can be easily calculated based on the outside air temperature. However, the present invention is not limited to such a method, and information on the humidity of the outside air may be acquired, and the dew point temperature may be obtained in consideration of the humidity information. As a method for acquiring humidity information, for example, a method of providing a humidity sensor for detecting humidity, or estimating the amount of solar radiation from the amount of power generated by the photovoltaic power generation panel 4, and determining the condition of sunny weather, cloudy weather, and rainy weather, For example, a method for estimating the humidity from the state can be mentioned. Further, in the present invention, for example, the dew point temperature is directly detected by a dew point detecting means such as a capacitance type dew point meter, or information on humidity and dew point temperature observed at a weather station or the like is acquired by communication. Also good.

  Moreover, the amount of heating to the water in the panel cooling device 3 changes according to the weather. For example, when it becomes cloudy temporarily, the amount of heating decreases, and the temperature of hot water flowing out from the panel cooling device 3 may become lower than the hot water storage temperature in the upper part of the hot water storage tank 1. In this case, the hot water from the panel cooling device 3 is mixed with the hot water in the upper part of the hot water storage tank 1, so that the hot water storage temperature in the upper part of the hot water storage tank 1 is lowered and the amount of stored hot water may be reduced. In order to avoid such a situation, the control device 7 detects the detected value of the temperature sensor 6d for detecting the hot water temperature at the upper part of the hot water tank 1, and the detected value of the temperature sensor 6c for detecting the temperature of the hot water flowing into the upper part of the hot water tank 1. When the temperature of hot water flowing into the upper part of the hot water storage tank 1 is lower than the hot water storage temperature of the upper part of the hot water storage tank 1 by a predetermined temperature difference or more, the opening degree of the three-way valve 5 is controlled and You may control to increase the flow volume of flowing hot water. If it operates in this way, the temperature of the water supplied to the panel cooling device 3 will rise. As a result, the temperature of the hot water flowing out from the panel cooling device 3 rises, so that the temperature of the hot water flowing into the upper part of the hot water storage tank 1 can be raised to the same level as the hot water temperature in the upper part of the hot water storage tank 1. For this reason, since it can avoid reliably that the amount of hot water storage heat reduces, the operation | movement of a more efficient apparatus is implement | achieved.

  Further, the flow rate of the pump 2 may be operated at a constant speed, or the flow rate may be controlled by changing the rotational speed by an inverter or the like according to the temperature condition. For example, when the temperature of hot water flowing into the upper part of the hot water storage tank 1 is lower than the hot water storage temperature of the upper part of the hot water storage tank 1, control may be performed to reduce the flow rate of the pump 2. Thereby, since the temperature rise width of the water by the heat exchange in the panel cooling device 3 becomes large, the temperature of the hot water flowing out from the panel cooling device 3 and flowing into the hot water storage tank 1 rises. As a result, a decrease in the hot water storage temperature of the hot water storage tank 1 is reliably suppressed, and a more efficient operation of the apparatus is realized.

  On the other hand, when the temperature of the hot water flowing out from the panel cooling device 3 is excessively high, a scale may be generated due to precipitation of calcium contained in the water, and the flow path may be easily blocked. Therefore, when the temperature of the hot water flowing out from the panel cooling device 3 is high (for example, 80 ° C. or higher), control for increasing the flow rate of the pump 2 may be performed. Thereby, the temperature of the hot water flowing into the upper part of the hot water storage tank 1 is lowered, and as a result, the production amount of scale is suppressed and the blockage of the flow path is avoided, so that a more reliable apparatus can be operated. it can.

  Condensation of the photovoltaic power generation panel 4 may be caused not only by cooling with water but also by a decrease in ambient air temperature. Therefore, the operation of maintaining the temperature of the panel cooling device 3 at or above the dew point temperature by driving the pump 2 and supplying water at or above the dew point temperature may be performed in addition to the time during the daytime power generation such as at night. . Thereby, the operation | movement which suppresses the dew condensation of the solar power generation panel 4 and improves reliability can be performed.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. 3. The description will focus on the differences from the first embodiment described above, and the same or corresponding parts will be denoted by the same reference numerals. Is omitted.

  In the first embodiment described above, one outlet for water is provided in the lower part of the hot water storage tank 1. On the other hand, as shown in FIG. 3, in the present embodiment, the hot water storage tank 1 is provided with a plurality of outlets 16 whose positions are different in the vertical direction, and the opening / closing valve 8 is provided corresponding to each outlet 16. Each is provided. In such a configuration, when the control device 7 selects opening / closing of each on-off valve 8, water can be taken out from an arbitrary outlet 16 and supplied to the panel cooling device 3. Since temperature stratification is formed inside the hot water storage tank 1, the higher the position of the outlet 16, the higher the temperature of the extracted water. For this reason, in this embodiment, the temperature of the water to be taken out can be selected by selecting the position from which the water is taken out from the plurality of outlets 16. This has the following advantages.

  When the water temperature in the lower part of the hot water storage tank 1 is extremely low, the flow rate of the hot water flowing through the bypass passage 13 when the water taken out from the outlet 16 in the lower part of the hot water storage tank 1 is supplied to the panel cooling device 3 is Even if the opening degree of the three-way valve 5 is controlled so as to be maximized, the temperature of the water supplied to the panel cooling device 3 may be less than the dew point temperature. In such a case, in the apparatus of the present embodiment, the control device 7 selects opening / closing of each on-off valve 8 based on the panel water inlet temperature detected by the temperature sensor 6a, so The outlet 16 can be switched. By this switching, the temperature of the water to be taken out increases, so that the temperature of the water supplied to the panel cooling device 3 can be set to the dew point temperature or higher. For this reason, it can prevent reliably that dew condensation arises in the photovoltaic power generation panel 4. FIG.

  In addition, when the operation of the apparatus is started, there is a possibility that the temperature of each part of the apparatus is low and the operation is more likely to cause condensation. Therefore, at the start of operation of the device, water is taken out from the outlet 16 at the top of the hot water storage tank 1 and after confirming that the temperature of the water supplied to the panel cooling device 3 is a temperature at which condensation can be avoided, The takeout port 16 may be sequentially switched to the lower one. By performing such an operation, even when the temperature of each part of the apparatus is low, such as at the start of the operation of the apparatus, it is possible to perform an operation that more reliably suppress condensation and increase reliability.

  Moreover, in this embodiment, the detected value of the temperature sensor 6d which detects the hot water storage temperature of the hot water storage tank 1 upper part by the control apparatus 7, and the detection value of the temperature sensor 6c which detects the temperature of the hot water which flows into the hot water storage tank 1 upper part, If the temperature of the hot water flowing into the upper part of the hot water storage tank 1 is lower than the temperature of the hot water stored in the upper part of the hot water storage tank 1 by a predetermined temperature difference or more, the outlet 16 for taking out the water is switched to the upper one. May be. By this control, the temperature of the water supplied to the panel cooling device 3 rises, so the temperature of the hot water flowing out from the panel cooling device 3 rises. As a result, the temperature of hot water flowing into the upper part of the hot water storage tank 1 can be increased to the same level as the hot water storage temperature in the upper part of the hot water storage tank 1. For this reason, since it can avoid reliably that the amount of hot water storage heat reduces, the operation | movement of a more efficient apparatus is implement | achieved.

  In the embodiment described above, the hot water storage tank 1 stores hot water while forming temperature stratification, and hot water is stored in the upper part and low temperature water is stored in the lower part. However, in the present invention, each part of the hot water storage tank is stored. Alternatively, a circulating warming hot water storage tank that heats up so that the temperature of the water becomes uniform may be used. Further, until the temperature in the hot water storage tank reaches a predetermined temperature or higher (for example, 30 ° C. or higher to avoid condensation), the water is boiled by the above-described circulation heating method, and thereafter, hot water is stored while forming a temperature stratification. Excessive boiling may be performed. When such an operation is performed, the temperature of the water supplied from the hot water storage tank 1 to the panel cooling device 3 is basically a temperature at which condensation can be avoided. However, since water having a dew point temperature or higher can be supplied without changing the outlet 16, the outlet 16 from the hot water storage tank 1 can be integrated into one, and a lower cost apparatus can be obtained.

DESCRIPTION OF SYMBOLS 1 Hot water storage tank 2 Pump 3 Panel cooling device 4 Solar power generation panel 5 Three-way valve 6a, 6b, 6c, 6d Temperature sensor 7 Control device 8 On-off valve 10 Outgoing flow path 11, 12 Return flow path 13 Bypass flow path 14 Water supply flow path 15 Hot water supply flow path 16 Outlet

Claims (5)

A hot water storage tank for storing hot water to be supplied to the load side,
Solar power panels,
A panel cooling device for cooling the solar power generation panel;
A forward flow path for sending water taken out from the hot water storage tank to the panel cooling device; and a return flow path for returning hot water generated by the water receiving heat of the photovoltaic power generation panel to the hot water storage tank. A circulation circuit;
A bypass flow path capable of injecting a part of the hot water flowing out from the panel cooling device into the forward flow path;
Inlet water temperature detecting means for detecting the temperature of water flowing into the panel cooling device;
Dew point temperature acquisition means for acquiring the dew point temperature of outside air;
A flow rate adjusting means for adjusting the flow rate of hot water flowing through the bypass flow path so that the incoming water temperature detected by the incoming water temperature detecting means is equal to or higher than the dew point temperature acquired by the dew point temperature acquiring means;
A solar water heater using   The flow rate adjusting means adjusts the flow rate of hot water flowing through the bypass channel so that the incoming water temperature falls within a range between the dew point temperature and a temperature higher than the dew point temperature by a predetermined temperature difference. Item 1. A solar water heater according to item 1. An outside temperature detecting means for detecting outside temperature is provided,
3. The solar-powered hot water supply apparatus according to claim 1, wherein the dew point temperature acquisition unit calculates the dew point temperature based on an outside air temperature detected by the outside air temperature detection unit. The hot water storage tank is provided with a plurality of outlets having different heights from which water to be sent to the panel cooling device can be taken out.
Any of Claim 1 thru | or 3 provided with the taking-out position selection means which selects the position which takes out the water sent to the said panel cooling device from these some taking-out ports according to the incoming water temperature detected by the said incoming water temperature detection means. The hot water supply apparatus using solar heat according to claim 1. Return temperature detection means for detecting the temperature of hot water flowing into the hot water storage tank from the return flow path;
Hot water storage temperature detecting means for detecting the temperature of the hot water stored in the upper part of the hot water storage tank;
Second flow rate adjusting means for adjusting the flow rate of hot water flowing through the bypass flow path based on the return temperature detected by the return temperature detecting means and the hot water storage temperature detected by the hot water storage temperature detecting means;
The solar-heat-use hot water supply apparatus of any one of Claims 1 thru | or 4 provided with these.

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