CN203771744U - Photovoltaic-driven solar active circulating type hot-water system - Google Patents

Abstract

The utility model relates to a solar active circulating hot water system driven by photovoltaics. Including a heat collector array, a first photovoltaic battery group, a first DC circulation pump, and a water tank, the first DC circulation pump is connected in series between the circulation inlet of the heat collector array and the water circulation outlet of the water tank, and the heat collector array The circulation outlet is connected with the water circulation inlet of the water tank; the input power terminal of the first DC circulation pump is electrically connected with the first photovoltaic battery group, and is driven by the first photovoltaic battery group; the hydraulic characteristics of the utility model system are related to the first DC circulation The volt-ampere characteristics of the matched pumps are matched with the volt-ampere characteristics of the output of the first photovoltaic cell group, and the output flow of the first DC circulation pump after matching changes with the radiation. The starting radiation of the utility model system is 100～150W/㎡; the required flow is smaller; the system is simple and stable. In actual operation, when the weather is good, the DC circulation system driven by photovoltaics is adopted, and there is no consumption of operating costs.

Description

A photovoltaic-driven solar active circulation hot water system

technical field

The utility model belongs to the field of comprehensive utilization of solar photoelectricity, light and heat, and specifically relates to the field of combined application of photovoltaic power generation and solar water heating systems.

Background technique

Solar energy is regarded as the most potential energy source in the future, and has become one of the industries that countries around the world are vying for development. my country has developed and utilized solar energy for several decades, and photothermal and photoelectric utilization technologies are becoming mature and have been widely used. In terms of light and heat, the solar water heating system in my country has been widely accepted by the society, and can be divided into passive circulation system and active circulation system according to the circulation mode. The passive circulation system requires the installation height of the storage device to be higher than that of the collector. It does not require circulation power, and the flow rate is proportional to the solar energy absorbed by the water heater. The maintenance is very simple, and it has been widely adopted by the society. But this kind of water heater (system) is only suitable for independent small-area use, and for large-scale hot water and heating systems, or hot water systems with high performance requirements, or hot water systems where the installation height of the water tank is not suitable for higher than the collector etc. Generally, an active circulation system is required. Moreover, in the hot water-heating-heat pump refrigeration integrated system that is currently being vigorously promoted, the solar water heating system incorporated in it must adopt an active circulation method. The current active circulation hot water system generally adopts the following control method: when the water temperature at the top of the collector is higher than the water temperature at the bottom of the water tank by 5, the controller starts the circulation pump. This kind of system has a constant flow rate and easy predictable performance. Under the same conditions, it can obtain higher water temperature than the natural circulation system, and it is easier to integrate with the building design and centralized management, and the user experience is better.

At present, the circulation power of the active circulation system is mostly commercial power, and the circulation is started and closed according to the temperature difference. In this way, the system depends on the power grid, and when the radiation is low, the pump may be turned on and off frequently, affecting the life of the system. Due to the intermittent circulation of the system, the circulation flow is always greater than the system needs. Using variable frequency pumps to replace AC circulating pumps can theoretically have a good energy-saving effect, but the technology of adjusting the speed of circulating pumps according to light intensity is too complicated, poor in stability, and high in cost, so it is not widely economical. It will be a good solution to convert the sunlight part into electric energy, as the circulation power of the system, and directly drive the DC pump. Chinese patents ZL200710029601.5, ZL201020277225.9, and ZL200710030104.7 all disclose systems that use solar power to generate electricity and then drive water pumps to lift water. The common structural feature of these systems is that the photovoltaic output requires an MPPT controller, a battery and a charge-discharge controller, and the power demand and hydraulic characteristics of this system are not directly related to radiation, so photovoltaic power is only used as a battery. The charging power supply, its battery composition and output volt-ampere characteristics have no direct impact on the performance of the system.

Utility model content

In order to realize the coupling relationship between the hydraulic characteristics of the hot water circulation system, the characteristics of the pump and the motor, and the output characteristics of photovoltaics, the circulation flow of the system changes with the intensity of the radiation, so that the required flow of the system is more accurate. The utility model provides a solar active circulation hot water system driven by photovoltaics.

The specific technical solutions are as follows:

A photovoltaic-driven solar active circulation hot water system includes more than one set of collector arrays 1, a first photovoltaic cell group 2, a first DC circulation pump 3, and a water tank 4, and the first DC circulation pump 3 Connected in series between the circulation inlet of more than one set of heat collector arrays 1 and the water circulation outlet of water tank 4, the circulation outlet of more than one group of heat collector arrays 1 is connected with the water circulation inlet of water tank 4; the first direct current circulation pump 3 The input power terminal of the input power supply terminal is electrically connected with the first photovoltaic cell group 2, and is driven by the first photovoltaic cell group 2; each group of collector arrays 1 is composed of solar flat panel collectors in series, and more than two groups of collectors The array 1 is connected in parallel; the first photovoltaic cell group 2 is a solar monocrystalline silicon photovoltaic cell group or a polycrystalline silicon photovoltaic cell group; the first DC circulation pump 3 is a DC brushless centrifugal circulation pump; the water tank 4 It is an insulated water tank; the hydraulic characteristics of the solar active circulating hot water system are matched with the volt-ampere characteristics of the first DC circulation pump 3 and the volt-ampere characteristics of the output of the first photovoltaic cell group 2. After matching, the first The output flow of the DC circulation pump 3 changes with the radiation, and the starting radiation of the solar active circulation hot water system is 100-150W/㎡.

When the radiation of the solar active circulation hot water system is 750-850W/㎡, the first direct current circulation pump 3 reaches the optimum flow rate and lift.

It also includes a coil heat exchanger 8, the coil heat exchanger 8 is located in the water tank 4, and the first DC circulation pump 3) is connected in series with the circulation inlet of more than one set of heat collector arrays 1 and the coil heat exchanger. Between the outlets of the working fluid of the heat exchanger 8 , the circulation outlets of more than one set of collector arrays 1 communicate with the inlet of the working fluid of the coil heat exchanger 8 .

It also includes a plate heat exchanger 5, the first DC circulation pump 3 is connected in series between the circulation inlet of more than one set of heat collector arrays 1 and the working fluid outlet of the plate heat exchanger 5, and more than one set of heat collectors The circulation outlet of the array 1 is connected with the working medium inlet of the plate heat exchanger 5; the water circulation outlet of the plate heat exchanger 5 is connected with the water circulation inlet of the water tank 4, and the water circulation inlet of the plate heat exchanger 5 is connected with the water circulation outlet of the water tank 4 The second DC circulation pump 6 is connected in series, the second DC circulation pump 6 is electrically connected with the second photovoltaic cell group 7, and is driven by the second photovoltaic cell group 7; wherein more than one group of heat collector arrays 1, plate heat exchangers 5 and the first DC circulation pump 3 form a primary system, i.e. the working fluid circulation system; the water tank 4, the plate heat exchanger 5 and the second DC circulation pump 6 form a secondary system, namely the water circulation system; the second DC circulation pump 6 is a DC brushless centrifugal circulation pump.

The design flow rate of the primary system is 0.003-0.015 L/(㎡s); the design flow rate of the secondary system is 0.008-0.05 L/(㎡s).

The rated operating voltages of the first DC circulating pump 3 and the second DC circulating pump 6 are multiples of 3.

The characteristics of the utility model structural design scheme are specified as follows:

1. The collector array, water tank and pipeline shall be constructed according to the design and construction method of the existing water heater system;

2. Match the hydraulic characteristics of the corresponding DC pump according to the hydraulic characteristics of the collector system pipeline. For the primary system with relatively uniform branch flow design, the design flow of the system is set at 0.003-0.015L/(㎡s), and when the system conditions permit, try to use a small flow value. For the secondary system, the design flow rate is between 0.008 and 0.05 L/(㎡s). At this time, the circulating hydraulic characteristics of the system basically satisfy H=RQ^2 (the value of R can be measured, or calculated according to the existing engineering standards from the pipeline composition scheme), and the best efficiency point of the selected pump should be as close as possible to or satisfy this formula. As shown in Figure 2, the intersection point of the resistance characteristic curve of the system and the characteristic curve of the pump is at the maximum efficiency point of the pump;

3. The DC pump selected by the system should use a brushless DC water pump as much as possible, and the pump body has a small starting current and a wide working voltage, and the rated working voltage is preferably a multiple of 3;

4. After the pump body is selected according to the above principles, it is necessary to match the corresponding first photovoltaic cell composition according to the overall input volt-ampere characteristic curve after the DC pump is installed on the circulation system. The specific principle is that the circulation pump starts when the irradiation is 100-150W/㎡, and the circulation starts. When the irradiance obtained on the collector plane is slightly higher than the average value of the 8-hour irradiance value in the local sunny weather (such as 800 W/㎡), the DC circulating pump reaches or approaches the optimal working condition of its design;

5. The output of the photovoltaic cell array matched by the system should meet (1) make the connected circulation pump start to cycle at 100-150W/㎡, (2) The input volt-ampere characteristic curve of the pump body is the same as that of the photovoltaic cell under different irradiation The intersection point of the output volt-ampere characteristic curves below is as far as possible near the left end of the maximum output power point of each curve. (3) When the average value of the 8-hour irradiation value in the local fine weather is slightly higher (such as 800 W/㎡) To achieve the best power output of photovoltaic cells. It should be noted that first of all, it is necessary to ensure that the starting irradiation value is not too large. Figure 3 is the volt-ampere characteristic curve of a typical brushless DC water pump connected to the circulation pipeline. The figure shows that the starting current of the brushless DC pump is much greater than its minimum operating current. As shown in Figure 4 (I_PV1000 is the output current of the photovoltaic cell under 1000W irradiation, I_PV500 is the output current of the photovoltaic cell under 500W irradiation intensity, and so on), the pump can only start when the irradiation exceeds 500W, and After starting, the input voltage of the pump changes very little, and the corresponding output flow changes only slightly. This is a bad match. The thermal efficiency of the system is very low, and even there is no obvious effective heat gain throughout the day. As shown in Figure 5, the area of the used battery is doubled compared to 4. After the pump is started, the flow rate changes with the intensity of the irradiation, but the pump still needs 500W of starting irradiation, and the irradiation energy within 500W is difficult to collect. The thermal performance is reduced by more than 40%. As shown in Figure 6, this is one of the matching methods used in this utility model. The area of the battery used is doubled compared to 5. At this time, the pump can be started after the irradiation exceeds 100W, and the output flow changes with the irradiation after starting. . In this case, the system can already collect solar heat very well, and the thermal efficiency of the system is basically the same as or even slightly higher than that of the traditional system. As shown in Figure 7, this is another matching method of the present invention, which improves the construction method of the photovoltaic cell array, so as to ensure that the system can start the cycle when the irradiation intensity is 100W, and the circulation flow of the system changes more with the irradiation. Obviously, the system performance is also better, and more importantly, the area of photovoltaic cells used is reduced by 25% to 40% compared to the method shown in Figure 5.

The beneficial technical effects of the utility model compared with the prior art are embodied in the following aspects:

1. The required flow rate of the hot water system is smaller. The existing hot water system uses temperature difference to control the opening and closing of the circulation flow to control the operation of the hot water system. The circulation flow of the system is basically a constant value during operation. In order to ensure that the system can still effectively collect For solar heat, the circulation flow value set by the system is too large for most of the day, and when the radiation is small, the system will open and close frequently. And in the system in the utility model, its circulating flow is strengthened along with the radiation, and the system flow is just small when the irradiation is small, so that the average flow of the system throughout the day is even smaller. The reduced flow rate required by the system means that the required pump power is smaller, and the pipe diameter used in the system can be reduced. For a measured system of 10㎡, the system designed according to current engineering standards requires an AC pump of about 60W. But in the same comparison system, the all-day thermal performance of the DC pump system using 14W can exceed that of the AC pump system;

2. The system is simple and stable, and can be adaptively controlled according to the radiation intensity. The system can work normally without additional controllers, battery energy storage, and battery charge and discharge controllers, and can largely avoid the problem of frequent start-up and shutdown of pumps that occurs in traditional temperature difference control schemes;

3. The system construction cost may be relatively lower, and the operation and maintenance cost is lower. The traditional hot water system requires a solar controller, an AC circulation pump, and needs to be connected to the city grid to consume electricity. When the hot water system in the utility model is driven, a solar battery panel and a direct current circulating pump are needed. However, since the required power of the DC circulation pump is much smaller than that of the AC pump, the cost of the DC pump may be lower than that of the required AC pump. Since the driving power required by the system is small and the area of the photovoltaic cells is small, the cost of the photovoltaic cells may even be lower than that of the solar controller. At the same time, there is no need to consume AC power during the operation of the system, and there is basically no operating electricity fee. Taking a measured 10㎡ system as an example, it adopts the existing engineering standard hot water system, uses a DN15 pipeline system, and is equipped with a 90W AC circulation pump and a solar system controller. The cost of the AC circulating pump is about 300 yuan, and the cost of the controller is 200 yuan. The DC circulation system driven by photovoltaics uses a 14W DC circulation pump and photovoltaic cells with a total peak power of 32W. The cost of the DC circulating pump is about 90 yuan, and the cost of the photovoltaic cell is about 160 yuan. Its total construction cost has been reduced by 250 yuan, and the photovoltaic drive system does not need to connect sensor probes, remote controllers, or AC power grids. The circuit connection during installation is simpler and more convenient. If the installation labor cost is calculated, its construction The cost is relatively reduced more. In actual operation, when the weather is good, the pump body of the AC pump system works for about 8 hours a day, and the power consumption is about 90W. The controller works 24 hours a day, and the power consumption is about 10W. The DC circulation system driven by photovoltaics does not consume operating costs.

Description of drawings

Figure 1 is a schematic diagram of the system.

Figure 2 is a characteristic curve diagram of a well-matched pump and system.

Fig. 3 is a measured input volt-ampere characteristic curve of the DC pump after it is used in the circulation system.

Fig. 4 is a graph of the volt-ampere characteristic curve of the photovoltaic cell and the system input under a condition of poor voltage matching.

Fig. 5 is a graph of the volt-ampere characteristic curve of the photovoltaic cell and the system input under a condition of good current matching.

Fig. 6 is a graph of the volt-ampere characteristic curve of the photovoltaic cell and the system input under a good matching condition.

Fig. 7 is a graph of the volt-ampere characteristic curve of the photovoltaic cell with the improved structure and the input of the system under a good matching condition.

Fig. 8 is a diagram of a photovoltaic-driven secondary circulation hot water system with a coil heat exchanger.

Fig. 9 is a diagram of a photovoltaic-driven secondary circulation hot water system with a plate heat exchanger.

Serial number in the above picture: collector array 1, first photovoltaic cell group 2, first DC circulation pump 3, water tank 4, plate heat exchanger 5, second DC circulation pump 6, second photovoltaic cell group 7, plate Tube heat exchanger 8.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is further described by embodiment.

Example 1

See Figure 1, a photovoltaic-driven direct-connected hot water system. It includes a set of heat collector array 1, a first photovoltaic cell group 2, a first DC circulation pump 3, and a water tank 4. The first DC circulation pump 3 is connected in series to the water circulation inlet of a set of heat collector array 1 and the water tank 4. Between the water circulation outlets, the water circulation outlets of a group of collector arrays 1 communicate with the water circulation inlets of the water tank 4; the input power terminal of the first DC circulation pump 3 is electrically connected with the first photovoltaic battery group 2, and is powered by the first photovoltaic battery Group 2 drives.

A set of collector array 1 adopts five flat-plate solar collectors of 1m×2m in parallel to form an array, and uses DN15 galvanized steel pipes to connect with a thermally insulated water tank 4 with a volume of 750L. The first DC circulating pump 3 is a brushless DC isolated water pump with a maximum lift of 5 meters, a maximum flow rate of 500L/h, an operating temperature of 100 degrees, a rated operating voltage of 12V, a maximum power of 14W, and a life span of 20,000 hours; all pipelines need to be well prepared insulation.

The first photovoltaic cell group 2 can have two structures a or b:

a. An array of 8 solar monocrystalline silicon photovoltaic cells with an open circuit voltage of 7.2V, an operating voltage of 6V, and a peak power of 4.5W connected in parallel and then connected in parallel. The total peak power of all the cells is 36W;

b. An array is formed by connecting parallel arrays and series arrays, and its structure diagram is shown in Figure 8. The parallel part is a photovoltaic module with an open circuit voltage of 3.6V, a working voltage of 3V and a short circuit current of 1.7A. The photovoltaic cells in the series connection have a short-circuit current of 13.8V and 1.7A. The total peak power of the cells in the entire array is 24.5W.

When the radiation of the solar active circulation hot water system is 800W/㎡, the flow rate of the first DC circulation pump 3 is 0.1L/s and the head is 1.7m.

Example 2

See Figure 8, a photovoltaic-driven secondary circulation hot water system. It includes a heat collector array 1 , a first photovoltaic cell group 2 , a first direct current circulation pump 3 , a water tank 4 and a coil heat exchanger 8 . The coil heat exchanger 8 is located in the water tank 4, the first direct current circulation pump 3 is connected in series between the circulation inlet of the collector array 1 and the working medium outlet of the coil heat exchanger 8, and the circulation outlet of the collector array 1 It communicates with the working medium inlet of the coil heat exchanger 8 .

Among them, collector array 1 consists of 21 1m×2m flat-plate collectors connected in parallel to form a group of 7, and then 3 groups are connected in parallel through DN25 galvanized pipes. The effective heat exchange area of the coil heat exchanger 8 is 15 square meters. The volume of water tank 4 is 3.5 tons. The first DC circulation pump 3 has a rated head of 8 meters, a rated flow rate of 2 cubic meters per hour, a voltage of 24V, and a maximum power of 180W. The open circuit voltage of the first photovoltaic cell group 2 is 30V, and the short circuit current is 10A.

When the irradiance of the solar active circulation hot water system is 800W/㎡, the flow rate of the first DC circulation pump 3 is 2.2 cubic meters per hour, and the lift is about 6 meters.

Example 3

See Figure 9, a photovoltaic-driven secondary circulation hot water system. Including the collector array 1, the first photovoltaic cell group 2, the first DC circulation pump 3, the water tank 4, the plate heat exchanger 5, the second DC circulation pump 6 and the second photovoltaic cell group 7; the first DC circulation The pump 3 is connected in series between the circulation inlet of the collector array 1 and the working medium outlet of the plate heat exchanger 5, and the circulation outlet of the collector array 1 is connected with the working medium inlet of the plate heat exchanger 5; the plate heat exchanger 5 The water circulation outlet of the water circulation outlet is connected to the water circulation inlet of the water tank 4, the water circulation inlet of the plate heat exchanger 5 is connected to the water circulation outlet of the water tank 4, and the second DC circulation pump 6 is connected in series between the second DC circulation pump 6 and the second photovoltaic cell group 7 Electrically connected, driven by the second photovoltaic cell group 7; more than one set of heat collector array 1, plate heat exchanger 5 and first DC circulation pump 3 form a primary system, that is, the working fluid circulation system; water tank 4, plate type The heat exchanger 5 and the second DC circulation pump 6 constitute a secondary system, namely a water circulation system; the second DC circulation pump 6 is a DC brushless centrifugal circulation pump.

The collector array 1 consists of 21 1mx2m flat-plate collectors connected in parallel to form a group of 7, and then 3 groups are connected in parallel through DN25 galvanized pipes. The equivalent heat exchange area of the plate heat exchanger 5 is about 30 square meters. Both the first DC circulation pump 3 and the second DC circulation pump 6 are brushless DC circulation pumps, and the first photovoltaic cell group 2 and the second photovoltaic cell group 7 are photovoltaic cell arrays composed of polycrystalline silicon photovoltaic cells. The volume of water tank 4 is 3.5 tons. The first DC circulation pump 3 has a rated lift of 8 meters, a rated flow rate of 2 cubic meters per hour, a voltage of 24V, and a maximum power of 180W. The second DC circulating pump 6 has a maximum lift of 5 meters, a maximum flow rate of 700L per hour, and a rated operating voltage of 12V. The first photovoltaic cell group 2 has an open circuit voltage of 30V and a short-circuit current of 10A, or a battery array with an open-circuit voltage of 7.2V and a short-circuit current of 5A in series and a battery array with an open-circuit voltage of 29V and a short-circuit current of 5A in parallel, as shown in FIG. 8 . The open-circuit voltage of the second photovoltaic cell group 7 is 14.4V and the short-circuit current is 3.4A, or it can be matched according to the scheme b in case 1.

When the irradiance of the solar active circulation hot water system is 800W/㎡, the flow rate of the first DC circulation pump 3 is 2.2 cubic meters per hour and the head is 6 meters; the flow rate of the second DC circulation pump 6 is 500L/h , The head is 1.6 meters.

Claims (6)

1. the solar energy active cycle formula hot-water heating system that photovoltaic drives, comprise more than one group collector array (1), the first photovoltaic cell group (2), the first direct current circulating pump (3), water tank (4), described the first direct current circulating pump (3) is connected between the circulation import of more than one group collector array (1) and the outlet of the water circulation of water tank (4), and the loop exit of more than one group collector array (1) and the water circulation import of water tank (4) are communicated with; The input supply terminal of the first direct current circulating pump (3) and the electrical connection of the first photovoltaic cell group (2), and driven by the first photovoltaic cell group (2), it is characterized in that: described every group of collector array (1) is for plate solar collector is by being composed in series, and collector array (1) more than two is by being connected in parallel; Described the first photovoltaic cell group (2) is solar energy single crystal Silicon photrouics group or polysilicon photovoltaic cells group; Described the first direct current circulating pump (3) is the centrifugal circulating pump of brush DC; Described water tank (4) is attemperater; C-V characteristic after the hydraulic characteristic(s) of described solar energy active cycle formula hot-water heating system is mated with the first direct current circulating pump (3) is mated mutually with the C-V characteristic of the first photovoltaic cell group (2) output, the output flow of the first direct current circulating pump (3) after coupling is along with irradiation changes and changes, and the starting irradiation of solar energy active cycle formula hot-water heating system is 100～150W/ ㎡.

2. the solar energy active cycle formula hot-water heating system that a kind of photovoltaic according to claim 1 drives, it is characterized in that: when the irradiation of described solar energy active cycle formula hot-water heating system is 750～850W/ ㎡, the first direct current circulating pump (3) reaches optimum flow and lift.

3. the solar energy active cycle formula hot-water heating system that a kind of photovoltaic according to claim 1 drives, it is characterized in that: also comprise coil heat exchanger (8), described coil heat exchanger (8) is positioned at water tank (4), described the first direct current circulating pump (3) is connected between the circulation import of more than one group collector array (1) and the sender property outlet of coil heat exchanger (8), and the loop exit of more than one group collector array (1) and the working medium import of coil heat exchanger (8) are communicated with.

4. the solar energy active cycle formula hot-water heating system that a kind of photovoltaic according to claim 1 drives, it is characterized in that: also comprise plate type heat exchanger (5), described the first direct current circulating pump (3) is connected between the circulation import of more than one group collector array (1) and the sender property outlet of plate type heat exchanger (5), and the loop exit of more than one group collector array (1) and the working medium import of plate type heat exchanger (5) are communicated with; The water circulation outlet of plate type heat exchanger (5) is being communicated with the water circulation import of water tank (4), the water circulation import of plate type heat exchanger (5) is being communicated with the second direct current circulating pump (6) of connecting between the water circulation outlet of water tank (4), the second direct current circulating pump (6) and the electrical connection of the second photovoltaic cell group (7), driven by the second photovoltaic cell group (7); Wherein more than one group collector array (1), plate type heat exchanger (5) and the first direct current circulating pump (3) form primary system, i.e. duplex matter system; Water tank (4), plate type heat exchanger (5) and the second direct current circulating pump (6) form electrical secondary system, i.e. water circulation system; Described the second direct current circulating pump (6) is the centrifugal circulating pump of brush DC.

5. the solar energy active cycle formula hot-water heating system that a kind of photovoltaic according to claim 4 drives, is characterized in that: the design discharge of described primary system be 0.003～0.015L/ (㎡ s); The design discharge of described electrical secondary system be 0.008～0.05L/ (㎡ s).

6. the solar energy active cycle formula hot-water heating system that a kind of photovoltaic according to claim 4 drives, is characterized in that: the multiple that the rated operational voltage of described the first direct current circulating pump (3) and the second direct current circulating pump (6) is 3.