Hybrid hot water supply system

Abstract

To provide a hybrid hot water supply system capable of efficiently generating and storing hot water of a high temperature required for hot water supply by maximizing use of solar heat energy while using a heat pump.SOLUTION: A hybrid hot water supply system 10 comprises a solar heat collector 11, a heat pump 12, a hot water storage tank 13, a circulation pump 29 that supplies water from the hot water storage tank 13 to the solar heat collector 11, and a solar panel 14 that drives the circulation pump 29. The solar heat collector 11 has a plurality of heat collection pipes that receives solar heat. When the water temperature in the hot water storage tank 13 is below a predetermined temperature and the amount of power generated by the solar panel 14 is equal to or larger than a power value required to drive the circulation pump 29, the solar heat collector 11 functions in priority to the heat pump 12, and supplies high-temperature hot water heated by the plurality of heat collection pipes to the hot water storage tank 13.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hybrid water heating system that utilizes solar heat and air heat, which are natural energies.

Background Art

[0002] In recent years, as a water heating system to replace gas water heaters, a heat pump water heating system using a natural refrigerant (CO2) has been increasingly used. Such a heat pump water heating system is composed of a heat pump and a hot water storage tank. The heat pump generates heat using CO2 as a refrigerant, and the hot water heated by the generated heat is stored in the hot water storage tank.

[0003] In a water heating system using a heat pump, since it is a technology that collects thermal energy in the air and uses it for water heating etc., there is an advantage that a large amount of heat can be utilized with a small amount of electric power. However, since heat is collected from the outside, there is a problem that the efficiency deteriorates when the outside air temperature is low etc. For this reason, a hybrid water heating system that combines a heat pump and solar energy to create a heat source that can be used for water heating etc. has been proposed.

[0004] The forms of utilization of solar energy include a method of directly converting it into electric power via a solar cell, and a method of converting heat generated by solar energy into hot water or steam and obtaining electric power by rotating a turbine. In the method of directly converting it into electric power using the solar cell, a plurality of solar panels in which a large number of solar cells are arranged are combined and used. However, there was a problem that the output voltage in one cell was usually as low as about 0.5 to 1.0 V, and the power generation efficiency was poor with respect to the equipment scale of the solar panel.

[0005] On the one hand, unlike the method of generating electricity through solar cells, solar thermal power generation uses heat collectors such as lenses and reflectors to collect sunlight, converting ordinary or cold water into hot water or steam, which is then used as an energy source to drive a turbine. This solar thermal power generation does not require the use of high-cost solar cells compared to solar photovoltaic power generation. Additionally, using heat collectors such as lenses and reflectors is more advantageous in terms of manufacturing and maintenance, and it also has the advantages of being able to concentrate energy and suppressing fluctuations in power generation through heat storage.

[0006] Patent Document 1 discloses a hybrid water heating system comprising a first hot water storage tank that heats and stores water using a fuel cell as a heat source, a second hot water storage tank that heats and stores water using solar heat as a heat source, and a mixing means for mixing the hot water from the first and second hot water storage tanks. In this hybrid water heating system, based on the water temperatures of the first and second hot water storage tanks, there is a control means for controlling the mixing ratio of the hot water from the first hot water storage tank and the hot water from the second hot water storage tank in the mixing means and the operation of the fuel cell, and it is configured to supply hot water within a preset temperature range.

[0007] Patent Document 2 discloses a hybrid water heating system comprising a single hot water storage tank that stores hot water heated using solar heat and the waste heat of a power generation unit. In this hybrid water heating system, a cooling layer for cooling the power generation unit is provided on the lower side within the hot water storage tank.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] In Patent Document 1, there is a first hot water storage tank that stores hot water using a fuel cell as a heat source and a second hot water storage tank that stores hot water using solar heat as a heat source. In addition, it is necessary to control the amount of hot water supplied from the first and second hot water storage tanks, and there is a problem that the system configuration becomes complicated.

[0010] In Patent Document 2, it is possible to control hot water supply by circulating water heated using a fuel cell and solar heat in one hot water storage tank. However, the heat collected by the solar panel cannot be directly converted into high-temperature hot water for hot water supply. For this reason, a heat exchanger for converting solar heat is required in the hot water storage tank.

[0011] Therefore, an object of the present invention is to provide a hybrid hot water supply system that can efficiently generate and store high-temperature hot water necessary for hot water supply by maximizing the utilization of solar heat energy while using a heat pump in combination.

Means for Solving the Problems

[0012] In order to solve the above problems, the hybrid hot water supply system of the present invention includes a solar heat collector using solar heat as a heat source, a heat pump using air heat as a heat source, a hot water storage tank that stores hot water heated by at least one of the solar heat collector and the heat pump, a circulation pump that supplies water from the hot water storage tank to the solar heat collector, and a solar power generation panel that generates electric power for driving the circulation pump. The hot water storage tank has a monitoring unit that monitors the amount and temperature of the hot water stored. The solar heat collector has a plurality of heat collection tubes that receive solar heat irradiation. When the water temperature monitored by the monitoring unit is less than a predetermined temperature and the amount of power generated by the solar power generation panel is equal to or greater than the power value required for driving the circulation pump, the solar heat collector functions preferentially to the heat pump and supplies high-temperature hot water heated by the plurality of heat collection tubes to the hot water storage tank.

Effects of the Invention

[0013] According to the hybrid water heating system of the present invention, when the water temperature is less than a predetermined temperature and the power generation amount by the solar power generation panel is equal to or more than the power value required for driving the circulation pump in the monitoring unit provided in the hot water storage tank, the solar heat collector functions preferentially over the heat pump. Thereby, it is possible to supply the necessary hot water with almost zero energy. Further, when the solar heat collector does not function, the heat pump functions preliminarily as necessary, so that a constant supply of hot water is always possible.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the hybrid water heating system according to the present invention will be described in detail based on the accompanying drawings. As shown in FIG. 1, the hybrid water heating system 10 of the present invention includes a solar heat collector 11 installed in a place where sunlight shines well, such as on the roof of a house, a heat pump 12 installed outdoors, and a heat pump 12. It is installed adjacent to the heat pump 12 and stores hot water while circulating the hot water heated by at least one of the solar heat collector 11 and the heat pump 12, and a hot water storage tank 13 that supplies hot water to various hot water supply devices in the house.

[0016] As shown in FIG. 2, the solar heat collector 11 is composed of an assembly of heat collection tubes 22 that receive solar heat irradiation, and functions by supplying water from the hot water storage tank 13 to each heat collection tube 22 via a circulation pump 29. The circulation pump 29 is driven according to the power generation amount of a solar power generation panel (solar panel) 14 provided alongside the solar heat collector 11.

[0017] The solar panel 14 is formed in a large panel shape by laying a plurality of solar cells called cells on a rectangular aluminum frame, and generates electric power when the light energy emitted by the sun hits the panel surface. The solar cells that make up the solar panel 14 are made of semiconductors such as silicon and compounds. When sunlight hits this semiconductor, the light energy is converted into electric energy according to the solar radiation intensity. The electric power generated by this solar panel 14 serves as a driving source for the circulation pump 29 that supplies water from the hot water storage tank 13. Therefore, as long as there is sunlight, the circulation pump 29 is driven only by the electric power from the solar panel 14, and water is constantly circulated and supplied to the solar heat collector 11. Since the electric power required to drive the circulation pump 29 is about 24V in direct current, it is sufficient to configure the solar panel 14 with the corresponding number of panels.

[0018] As shown in FIG. 2, the solar heat collector 11 includes a plurality of heat collection tubes 22 that receive solar heat irradiation, and by circulating the water pumped up by the circulation pump 29 through the plurality of heat collection tubes 22, high-temperature water at a constant temperature is generated. The high-temperature water generated here is stored in the hot water storage tank 13 while being maintained at 90°C or higher. And when the hot and cold water in the hot water storage tank 13 falls below a predetermined temperature (for example, 90°C), it is circulated again by the circulation pump 29 towards the plurality of heat collection tubes 22 to generate high-temperature hot and cold water. In this embodiment, the temperature of the hot and cold water stored in the hot water storage tank 13 is set to 90°C or higher as an example, but it is not limited to this temperature and can be set as appropriate according to the hot water supply application, season, etc.

[0019] The heat pump 12 is a known technology, so a detailed description thereof will be omitted. It collects heat from the atmosphere outdoors, exchanges heat, and forms hot and cold water. The mechanism is that a low-temperature refrigerant (CO2) absorbs heat from the atmosphere, is compressed to high temperature and high pressure by a compressor, and heat is exchanged with the water supplied with water to generate high-temperature hot and cold water. The driving source of the heat pump 12 is electric energy. However, since heat in the air is lifted and compressed to high temperature and high pressure by a compressor, the power consumption can be suppressed to about 1 / 3 compared to driving only with electric energy. The hot and cold water generated by this heat pump 12 is stored in a hot water storage tank 13 in the same manner as the solar collector 11.

[0020] When combined with the above heat pump 12, the hot water storage tank 13 becomes an independent hot water supply system called Eco Cute (registered trademark). In the present invention, in combination with the solar collector 11, a hybrid hot water supply system composed of two heat sources, air heat and solar heat, is configured. A water supply pipe 13a for supplying tap water and a hot water supply pipe 13b for supplying hot water to hot water supply devices such as a bathtub and a washbasin are piped to the hot water storage tank 13. The hot water storage tank 13 and the solar collector 11 are connected via a first inflow main pipe 16 and a first outflow main pipe 17, and the hot water storage tank 13 and the heat pump 12 are connected via a second inflow main pipe 18 and a second outflow main pipe 19. The first inflow main pipe 16 and the first outflow main pipe 17 are connected to the upper part of the hot water storage tank 13, and the second inflow main pipe 18 and the second outflow main pipe 19 are connected to the lower part of the hot water storage tank. As a result, the upper part in the hot water storage tank 13 becomes a high-temperature layer where hot and cold water heated by the solar collector 11 and the heat pump 12 circulates, and the lower part in the hot water storage tank 13 can be a low-temperature layer for cooling the heat pump 12.

[0021] The above-mentioned hot water storage tank 13 is equipped with a water volume monitoring unit, which is a known technology for detecting the water volume of water supply and hot water storage, and a water temperature monitoring unit for monitoring the temperature of the stored hot water. The water volume monitoring unit keeps the water volume in the hot water storage tank 13 constant, and the water temperature monitoring unit controls whether to select either the solar collector 11 or the heat pump 12 to generate high-temperature hot water. Here, when the temperature of the hot water monitored by the water temperature monitoring unit is less than a predetermined temperature (90°C), and the power generation amount by the solar power generation panel 14 is equal to or more than a sufficient power value to drive the circulation pump 29, the solar collector 11 functions prior to the heat pump 12. Thereby, high-temperature hot water can be generated without using commercial power. On the other hand, when the power generation amount by the solar power generation panel 14 becomes a power value insufficient to drive the circulation pump 29, the heat pump 12 can be activated as necessary.

[0022] Next, the details of the solar collector 11 will be described. As shown in FIG. 2, the solar collector 11 includes an inflow header pipe 23 and an outflow header pipe 24 extending in the horizontal direction, and a plurality of heat collection pipes 22 that take in water W1 heated from the inflow header pipe 23, heat this water W1 into high-temperature water, and discharge it to the outflow header pipe 24. The heat collection pipe 22 has an outer pipe 25 for introducing water W1 to a predetermined water level, an inner pipe 26 inserted into the outer pipe 25 through which the heated high-temperature water passes, and a vacuum glass pipe 27 covering the outer pipe 25.

[0023] The solar collector 11 is configured by appropriately combining a heat collection unit 40 that houses an inflow header pipe 23 and an outflow header pipe 24 of a predetermined length and a plurality of heat collection pipes 22 in a frame 38 according to the installation space and the heat collection capacity of solar heat. The heat collection units 40 are connected in parallel via connecting members 35 provided at both ends of the respective inflow header pipes 23 and outflow header pipes 24, and are arranged in the direction of receiving direct sunlight so that the inflow and outflow to each heat collection pipe 22 are on the lower side. Note that it is preferable to set the inclination angle of the heat collection pipe 22 to about 35 to 45 degrees with respect to the ground surface.

[0024] As shown in FIGS. 3 and 4, the heat collecting tube 22 has a connection portion where the lower opening 25a of the outer tube 25 into which the inner tube 26 is inserted branches off from the inflow header tube 23, and a first space portion 31 where the gap between the inner peripheral surface of the outer tube 25 and the outer peripheral surface of the inner tube 26 is filled with water W1. Further, a second space portion 32 filled with high-temperature water just before boiling of the water W1 is formed between the closed upper end (closed portion) 25b of the outer tube 25 and the upper opening end 26a of the inner tube 26. The high-temperature water further heated in this second space portion 32 is pushed out from the upper opening end 26a of the inner tube 26 toward the lower opening end 26b, and flows out into the outflow header tube 24 that joins and is connected to this lower opening end 26b. In order to efficiently obtain solar heat H through the vacuum glass tube 27, it is preferable to provide heat collecting fins 28 on the outer peripheral portion of the outer tube 25 as shown in FIGS. 3 and 4.

[0025] The outer tube 25 and the inner tube 26 are formed of copper with high thermal conductivity, particularly oxygen-free copper, and heat collecting fins 28 are provided on the outer tube 25 so as to project outward. These heat collecting fins 28 are provided to efficiently absorb the solar heat H irradiated through the vacuum glass tube 27 from the outer tube 25 to the inner tube 26. In this embodiment, a pair of heat collecting fins 28 are provided facing each other in the longitudinal direction of the outer tube 25, but the heat collecting effect can be increased by setting a wide surface area of these heat collecting fins 28 or arranging a plurality of them radially. The material of the heat collecting fins 28 is thinly processed and attached with a copper material having the same high thermal conductivity as the inner tube 26 and the outer tube 25, or is integrally formed with the outer tube 25.

[0026] The vacuum glass tube 27 is formed in a cylindrical shape by double glass with a vacuum inside, and completely covers the outer tube 25. The space between this vacuum glass tube 27 and the outer tube 25 is an air layer, and by heating this air layer with sunlight pouring through the vacuum glass tube 27, the outer tube 25 and the inner tube 26 can be heated to a high temperature. Further, by forming a black solar heat selective absorption film inside the double glass of this vacuum glass tube 27, it becomes possible to heat the air layer to a higher temperature.

[0027] The vacuum glass tube 27 is disposed so as to cover the inflow header tube 23 from the tip portion of the outer tube 25. However, its open end is not sealed and is only covered with a coarse heat insulating material. Therefore, it is possible to prevent the air layer heated through the vacuum glass tube 27 from expanding excessively, and it is possible to prevent the vacuum glass tube 27 from bursting or the like. Further, even when the vacuum glass tube 27 is damaged or deteriorated due to an external impact, aging, or the like, it can be easily replaced, which is also advantageous in terms of maintainability.

[0028] In the heat collecting tube 22 constituting the solar heat collector 11 of the present invention, as shown in FIG. 4, water W1 is introduced into the first space portion 31 from the lower part of the outer tube 25, and the high-temperature water heated in this first space portion 31 is sequentially sent out to the second space portion 32 and can be heated to a higher temperature by the closing portion 25b of the outer tube 25. As a result, since the high-temperature water can be pushed out all at once from the upper opening end 26a to the lower opening end 26b of the inner tube 26 inserted into the outer tube 25, as shown in FIG. 1, the high-temperature water W2 heated to a high temperature can be made to flow out into the hot water storage tank 13 connected to the tip of the outflow header tube 24.

[0029] According to the structure of the heat collecting tube 22, by supplying water W1 into the outer tube 25, the water W1 can be heated to a high temperature by the solar heat H pouring down through the vacuum glass tube 27 and converted into water W2 heated to 90 ° C. or higher just before boiling in a short time. Further, since the inner tube 26 is arranged along the central axis of the outer tube 25, the generated high-temperature water does not disperse and is likely to be concentrated in the inner tube 26. As a result, the high-temperature water heading for the outflow header tube 24 can be vigorously discharged.

[0030] Figure 5 shows the operation flow of the hybrid water supply system 10 of the present invention. When the system is started, tap water is supplied into the hot water storage tank 13 (ST01). The water volume in the hot water storage tank 13 is detected, and water is supplied until the water volume reaches the set value (ST02). Next, the water temperature in the hot water storage tank 13 is detected (ST03). If the temperature has not reached a predetermined temperature (90 °C) or higher, first, the power generation amount by the solar panel 14 is detected (ST04). When this power generation amount reaches a predetermined power value, the circulation pump 29 operates, and water is supplied from the hot water storage tank 13 to the solar collector 11 through the first inflow main pipe 16 (ST05). The supplied water W1 is heated while passing through the plurality of heat collection pipes 22 as shown in FIGS. 3 and 4, and the high-temperature water W2 is returned into the hot water storage tank 13 through the first outflow main pipe 17. This operation is continued while the hot water in the hot water storage tank 13 maintains 90 °C or higher.

[0031] While the circulation pump 29 is operating, the heat pump 12 is stopped, and electrical energy by commercial power is not consumed. On the other hand, when the power generation amount from the solar panel 14 cannot be obtained due to night or weather conditions and the circulation pump 29 does not operate, the supply of commercial power to the heat pump 12 becomes possible. Thus, by driving the heat pump 12 as needed (ST06), hot water supply can be continued. Note that the power supply to the heat pump 12 is performed at an arbitrary timing or at a preset time.

[0032] In the hot water storage tank 13, the temperature of the stored water is constantly monitored by the monitoring unit (ST07). When the water temperature drops below 90 °C, at least one of the solar collector 11 and the heat pump 12 operates according to the power generation amount of the solar panel 14 to keep the water temperature at 90 °C or higher (ST04 - ST07). While the water temperature in the hot water storage tank 13 maintains 90 °C or higher for a predetermined time, the solar collector 11 and the heat pump 12 stop (ST08). Note that since the solar panel 14 can receive sunlight even while the heat pump 12 is operating, if a predetermined power generation amount is reached and the circulation pump 29 operates, the power supply to the heat pump 12 stops, and heating and hot water storage are performed only by solar energy.

[0033] In this way, according to the power generation amount of the solar panel 14 sufficient for the operation of the circulation pump 29, hot water supply can be selected from either the solar heat collector 11 or the heat pump 12, enabling hot water supply at all times for 24 hours. In particular, while only the solar heat collector 11 is functioning, the consumption of commercial power becomes zero. Further, in the case of the solar heat collector 11 having the structure of the present invention, since high-temperature hot water necessary for hot water supply can be directly generated by receiving sunlight irradiation, even when switching from electrical energy to solar energy, high-temperature hot water necessary for hot water supply can be efficiently generated in a short time, and power saving is significantly improved.

Explanation of Reference Numerals

[0034] 10 Hybrid hot water supply system 11 Solar heat collector 12 Heat pump 13 Hot water storage tank 13a Water supply pipe 13b Hot water supply pipe 14 Solar panel (photovoltaic panel) 16 First inflow main pipe 17 First outflow main pipe 18 Second inflow main pipe 19 Second outflow main pipe 22 Heat collecting pipe 23 Inflow header pipe 24 Outflow header pipe 25 Outer pipe 25a Opening 25b Closing part 26 Inner pipe 26a Upper opening end 26b Lower opening end 27 Vacuum glass tube 28 Heat collecting fin 29 Circulation pump 31 First space part 32 Second space part 35 Connecting member 38 Frame 40 Heat collecting unit

Claims

1. A hybrid water heating system comprising a solar heat collector using solar heat as a heat source, a heat pump using air heat as a heat source, a hot water storage tank for storing hot water heated by at least one of the solar heat collector and the heat pump, a circulation pump for supplying water from the hot water storage tank to the solar heat collector, and a solar power generation panel for generating electric power to drive the circulation pump, wherein the hot water storage tank has a monitoring unit for monitoring the amount and temperature of the hot water stored therein, the solar heat collector has a plurality of heat collecting tubes for receiving solar heat irradiation, when the water temperature monitored by the monitoring unit is less than a predetermined temperature and the power generation amount by the solar power generation panel is equal to or more than the power value required for driving the circulation pump, the solar heat collector functions preferentially to the heat pump, and supplies high-temperature hot water heated by the plurality of heat collecting tubes to the hot water storage tank.

2. The hybrid water heating system according to claim 1, wherein the temperature of the hot water heated by the plurality of heat collecting tubes is equal to or more than a predetermined temperature and equal to or less than the boiling temperature.

3. The hybrid water heating system according to claim 2, wherein the predetermined temperature of the hot water heated by the plurality of heat collecting tubes is 90°C.

4. The hybrid water heating system according to claim 1, wherein the circulation pump is driven when the power generation amount by the solar power generation panel is equal to or more than a predetermined power value.

5. The hybrid water heating system according to claim 1, wherein when the monitoring unit of the hot water storage tank detects a water temperature less than a predetermined temperature and the power generation amount by the solar power generation panel is less than the power value required for driving the circulation pump, the heat pump operates preferentially.

6. The hybrid water heating system according to claim 1, wherein a first inflow main pipe and an outflow main pipe for circulating hot water through the solar heat collector are connected to the upper side of the hot water storage tank, and a second inflow main pipe and an outflow main pipe for circulating hot water through the heat pump are connected to the lower side of the hot water storage tank.

7. The heat collecting tube of the hybrid water heating system according to claim 1 comprises an inflow header pipe, an outflow header pipe, an outer pipe which branches from the inflow header pipe and extends with a closed tip, an inner pipe which is inserted into the outer pipe and has an upper opening end facing the closed tip of the outer pipe and a lower opening end connected to the outflow header pipe, a first space portion provided between the inner peripheral surface of the outer pipe and the outer peripheral surface of the inner pipe, a second space portion provided between the closed tip of the outer pipe and the upper opening end of the inner pipe, and a vacuum glass tube which is mounted so as to cover the outer pipe and receives sunlight irradiation.

Images