Reinforced heat supply system based on cascade heat storage device

Abstract

The invention discloses an intensified heat supply system based on a cascade heat storage device, and belongs to the technical field of domestic heat supply systems, the intensified heat supply system comprises a phase change heat storage device and a water tank which are arranged indoors, and a solar heat collector arranged outdoors, and the solar heat collector is communicated with the two ends of a heat charging pipe of the phase change heat storage device through pipelines respectively; the water tank is respectively communicated with heat release pipes of the phase change heat storage device through pipelines; the heat charging pipe is of an approximate heart-shaped structure; the water tank is communicated with a domestic water inlet and a heat user side outlet, and an auxiliary electric heating device is arranged in the water tank. The enhanced heat supply system based on the cascade heat storage device is simple in structure, high in solar energy utilization rate and capable of guaranteeing efficient hot water supply under different weather conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of domestic water supply systems, and in particular to an enhanced heating system based on a cascade heat storage device. Background Art

[0002] Solar energy is the earliest renewable energy used by humans. It has the advantages of wide distribution, easy access, renewable, and no pollution to the environment. At present, the use of solar energy is common in solar power generation and solar water heating, and the technology is relatively mature. Although solar water heating technology has many advantages, it cannot operate on cloudy days, nights, and rainy days due to lack of sufficient light. Therefore, it is necessary to store the heat generated by solar energy and release it during the period of lack of light to achieve the purpose of providing hot water for the equipment all day long. At present, most of the existing technologies use natural gas and heat pumps as heat sources, which makes it impossible to guarantee the supply of hot water in areas without natural gas supply or under severe weather conditions. In addition, existing heat storage technologies include thermochemical heat storage, sensible heat storage, and phase change heat storage. The heat storage density of phase change heat storage is 5 to 10 times or even higher than that of sensible heat storage. Due to the advantages of constant temperature and high heat storage density, phase change heat storage technology has been widely studied.

[0003] Patent No. CN2851981Y discloses a solar water heater phase change heat storage device, which utilizes the property of being able to store or release a large amount of heat during the phase change process of crystals. It includes a phase change heat storage device filled with crystals, and a bracket is installed on the outside of a circular cylinder to form a heat storage device. When the weather is clear, the water temperature in the solar water heater water storage tank continues to rise, causing the substances in the phase change heat storage device to absorb heat and change from solid to liquid. When there is no sunlight, the substances in the phase change heat storage device begin to change from liquid to solid, generating a large amount of heat to increase the water temperature in the water storage tank, so as to ensure that hot water of a certain temperature is available for use. The disadvantages of the above-mentioned prior art are: (1) a single phase change heat storage material is used, and its heat storage and heat release performance is relatively weak compared with multi-stage phase change heat storage devices; (2) it can only charge or release heat separately, and cannot charge and release heat at the same time, which cannot meet the requirements of heat users for simultaneous charging and releasing heat; (3) due to the use of a single melting point phase change material, it is impossible to store and utilize heat energy according to quality.

[0004] Patent No. CN112414193B discloses a multi-stage phase change heat storage device with built-in fins and a method for enhancing heat transfer. The heat transfer fluid flows through each phase change heat storage unit through the heat transfer fluid channel; the fins are built into the phase change material side of each phase change heat storage unit and close to the outer wall of the heat transfer fluid channel. The disadvantages of the above-mentioned prior art are: (1) The heat exchange tube is located in the center, resulting in slow melting of the bottom phase change material; (2) Although the method of adding fins enhances the performance of the heat storage device, it increases the manufacturing cost and reduces the filling amount of the phase change material. Summary of the invention

[0005] In order to solve the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide an enhanced heating system based on a cascade heat storage device, which has a simple structure and high solar energy utilization rate and can ensure efficient hot water supply under different weather conditions.

[0006] The technical solution adopted by the present invention to solve the technical problem is:

[0007] Provided is an enhanced heating system based on a cascade heat storage device, comprising a phase change heat storage device and a water tank arranged indoors, and a solar collector arranged outdoors, wherein the solar collector is connected to both ends of a heat charging pipe of the phase change heat storage device through pipelines, and the water tank is connected to a heat releasing pipe of the phase change heat storage device through pipelines;

[0008] The heat-filling tube is approximately a heart-shaped structure;

[0009] The water tank is connected with a domestic water inlet and a heat user-side outlet, and an auxiliary electric heating device is arranged in the water tank.

[0010] Furthermore, the phase change heat storage device is filled with a phase change material, and the phase change material is composed of three materials, namely lauric acid, Mg(NO3)2·6(H2O)NH4NO3 and paraffin.

[0011] Furthermore, the heat charging tube is located below the heat releasing tube.

[0012] Furthermore, the liquid flow directions in the heat charging tube and the heat releasing tube are opposite.

[0013] Furthermore, the outlet end of the heat release pipe is connected to the upper part of the water tank through a pipeline, and the inlet end is connected to the lower part of the water tank through a pipeline;

[0014] The domestic water inlet is communicated with the lower part of the water tank, and the heat user-side outlet is communicated with the upper part of the water tank.

[0015] Furthermore, a radiator is provided on the pipeline connecting the outlet of the heat charging pipe and the solar collector.

[0016] Furthermore, it also includes an air source heat pump connected to the water tank.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. In the enhanced heating system based on the cascade heat storage device of the present invention, the heat charging tube adopts a tube with a nearly heart-shaped structure (hereinafter referred to as the heart-shaped tube). Compared with the round tube, the liquid phase rate of the phase change material is slightly higher under the condition that the power of the heat releasing tube is the same, and the heat storage rate of the heat charging tube is higher;

[0019] 2. In the enhanced heating system based on the cascade heat storage device of the present invention, the heat exchange fluid in the heat-charging tube flows from the high-melting-point phase change material to the low-melting-point phase change material, and the heat exchange fluid in the heat-releasing tube flows from the low-melting-point phase change material to the high-melting-point phase change material, thereby avoiding the waste of high-grade heat and improving the utilization rate of low-grade heat;

[0020] 3. The enhanced heating system based on the cascade heat storage device of the present invention, because the heat charging pipe and the heat releasing pipe use different pipes, can perform heat storage and heat release processes simultaneously without affecting each other, which greatly improves the adaptability to actual conditions;

[0021] 4. In the enhanced heating system based on the cascade heat storage device of the present invention, the heat charging pipe is located below the heat releasing pipe, and the heat charging pipe is placed in the middle and lower part. Compared with placing the heat charging pipe in the middle and upper part, this design strengthens the natural convection during the heat absorption and melting process of the phase change material, accelerates the melting speed of the phase change material, and improves the heat charging efficiency;

[0022] 5. In the enhanced heating system based on the cascade heat storage device of the present invention, the phase change material adopts three materials connected in series or in parallel, and the phase change temperature of the phase change material is from high to low, and the flow direction of the heat pipe fluid is arranged in series or in parallel. Studies have shown that the heat storage performance is better when the phase change heat storage units are connected in series;

[0023] 6. The enhanced heating system based on the cascade heat storage device in the example of the present invention has a large water tank, and the water inside the water tank will be stratified due to different temperatures. The high-temperature domestic water is at the top of the water tank, and the low-temperature domestic water is at the bottom of the water tank. Therefore, the system sets the domestic water inlet at the bottom of the water tank, so that the low-temperature domestic water introduced into the water tank is directly injected into the bottom of the water tank, and the domestic water taken from the heat user side is drawn from the top of the water tank, thereby reducing the mixing of stratified domestic water in the water tank as much as possible, and improving the overall system efficiency;

[0024] 7. The enhanced heating system based on the cascade heat storage device in the example of the present invention is affected by natural weather. Sometimes the heat generated by the solar collector cannot meet the demand of the heat user side. At this time, an auxiliary electric heating device and an air source heat pump can be used to assist in heating domestic water;

[0025] 8. In the enhanced heating system based on the cascade heat storage device of the present invention, although the thermal efficiency of the air source heat pump is much higher than that of the auxiliary electric heating device, when the external environment is extremely cold, if the air source heat pump is used, the water generated by the compressed air in the heat generation process of the air source heat pump will not be discharged from the air source heat pump in time, and will have frozen inside the air source heat pump, making the air source heat pump itself and the pipes for transporting domestic water extremely easy to be damaged. Therefore, in extremely cold weather, an auxiliary electric heating device should be used for auxiliary heating. This design increases the adaptability of this system to the environment;

[0026] 9. The enhanced heating system based on the cascade heat storage device of the present invention uses three phase change materials with different melting points, so different heat sources can be used according to the change of outdoor temperature. When the outdoor temperature is high, the heat can be directly sent to the radiator for heating after the heat release pipe flows through the area with the lowest phase change temperature or flows through the area with the lowest phase change temperature and the medium temperature area, thereby increasing the utilization rate of energy;

[0027] 10. The enhanced heating system based on the cascade heat storage device in the example of the present invention can store the heat at the collector outlet separately according to the different qualities of the heat at the collector outlet, as the different solar irradiances will cause the outlet temperature of the solar collector to change. In addition, the area and flow rate of the heat exchange fluid entering the heat release tube of the phase change heat storage device can be adjusted according to the different uses of the heat users, so as to obtain water with a temperature that meets the needs of the heat users, thereby further improving the energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0029] Figure 1 It is a schematic diagram of the structure of the present invention;

[0030] Figure 2 is a cross-sectional view of a phase change heat storage device;

[0031] Figure 3 It is a comparative analysis diagram of heat storage and release rates of a heart-shaped heat-charging tube and a circular heat-charging tube with the same hydraulic radius under the flow conditions of the heat exchange fluid with the same mass flow rate.

[0032] In the figure: 1-phase change heat storage device, 2-water tank, 3-solar collector, 4-domestic water inlet, 5-heat user side outlet, 6-auxiliary electric heating device, 7-air source heat pump, 8-radiator, 9-heat charging pipe, 10-heat releasing pipe, 11-phase change material. DETAILED DESCRIPTION

[0033] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] like Figure 1-2As shown, this embodiment provides an enhanced heating system based on a cascade heat storage device, including a phase change heat storage device 1 and a water tank 2 arranged indoors, and a solar collector 3 arranged outdoors. The solar collector 3 is connected to both ends of the heat charging pipe 9 of the phase change heat storage device 1 through pipelines, and the water tank 2 is connected to the heat release pipe 10 of the phase change heat storage device 1 through pipelines. The high-temperature working fluid heated by the solar collector 3 enters the heat charging pipe 9. In the phase change heat storage device 1, the high-temperature working fluid and the phase change material 11 undergo heat exchange to become a low-temperature working fluid, and then flows into the solar collector 3 again to be heated; the water in the water tank 2 enters the heat release pipe 10, exchanges heat with the phase change material 11, and then the heated high-temperature domestic water is sent to the water tank 2 for storage. In addition, a radiator 8 is provided on the pipeline connecting the outlet of the heat charging pipe 9 and the solar collector 3, and the radiator 8 can be used to heat the room.

[0036] In this embodiment, the heat charging tube 9 is approximately a heart-shaped structure, and the heat charging tube 9 is located above the heat releasing tube 10. Compared with the circular tube, the heart-shaped tube has a smaller entropy generation, the liquid phase rate of the phase change material 11 is faster, and the heat releasing tube can release higher power after the liquid phase rate is stable. The heat charging tube 9 is placed in the lower middle part. Compared with placing the heat charging tube 9 in the upper middle part, this design strengthens the natural convection during the heat absorption and melting process of the phase change material 11, accelerates the melting rate of the phase change material 11, and improves the heat charging efficiency. In addition, the liquid flow direction in the heat charging tube 9 is opposite to that in the heat releasing tube 10, so that when the domestic water flows through the heat exchange pipe, the temperature of the surrounding phase change material 11 is gradually increased, so that the domestic water is gradually heated, reducing the amount of entropy generated in the process of heating the domestic water, and improving the heat utilization rate. The heat charging tube 9 and the heat releasing tube 10 of the phase change heat storage device 1 are designed independently. Since the heat charging tube 9 and the heat releasing tube 10 use different pipes, the heat storage and heat releasing processes can be performed simultaneously without affecting each other, which greatly improves the adaptability to actual conditions.

[0037] The time a household uses hot water for a single time is generally 10 to 30 minutes (such as taking a shower). In order to be more realistic, the heat storage and release rates of a single pair of hot and cold pipes working simultaneously for half an hour when the phase change material is completely solidified (phase change material 15°C) and when the phase change material is completely melted (phase change material 60°C) are simulated.

[0038] Figure 3 The heat storage and release rates of the heart-shaped heat-charging tube and the circular heat-charging tube in the completely melted and solidified states of the phase change material under the same mass flow rate and hydraulic radius. It can be seen from the figure that the heat storage efficiency and heat release efficiency of the heart-shaped tube are higher than those of the circular tube.

[0039] A heart-shaped heat charging tube with a concave cross-section at the upper end reduces the amount of solid phase change material sandwiched between the heat charging tube and the heat releasing tube during the simultaneous charging and releasing process, thereby improving the stability of the domestic water temperature at the heat releasing tube outlet of the phase change material heat storage device, thereby reducing the fluctuation of the domestic water temperature at the outlet of the phase change material heat storage device.

[0040] In addition, the phase change material 11 of this embodiment is made of three materials connected in series, and the phase change material 11 is lauric acid, Mg(NO3)2·6(H2O)NH4NO3 and paraffin.

[0041] In addition, the outlet end of the heat release pipe 10 is connected to the top of the water tank 2 through a pipeline, and the inlet end is connected to the bottom of the water tank 2 through a pipeline; the domestic water inlet 4 is connected to the bottom of the water tank 2, and the heat user side outlet 5 is connected to the top of the water tank 2. Since the water tank 2 used is relatively large, the water inside the water tank 2 will be stratified due to different temperatures. The high-temperature domestic water is at the top of the water tank 2, and the low-temperature domestic water is at the bottom of the water tank 2. Therefore, the system sets the domestic water inlet 4 at the bottom of the water tank 2, so that the low-temperature domestic water introduced into the water tank 2 is directly injected into the bottom of the water tank 2, and the domestic water taken from the heat user side is drawn from the top of the water tank 2, thereby reducing the mixing of stratified domestic water in the water tank 2 as much as possible, and improving the overall system efficiency.

[0042] In this embodiment, the water tank 2 is also provided with an auxiliary electric heating device 6, and the water tank 2 is also connected to an air source heat pump 7. If the heat produced by the solar collector 3 is not enough to heat the domestic water to the required temperature on the heat user side due to cloudy days or nights, the auxiliary electric heating device 6 or the air source heat pump 7 can be used to auxiliary heat the domestic water in the water tank 2. Finally, when the domestic water in the water tank 2 meets the heat user's demand, the high-temperature domestic water is led out through the heat user side outlet 5, thereby achieving the purpose of meeting the user's domestic hot water demand. Although the thermal efficiency of the air source heat pump 7 is much higher than that of the auxiliary electric heating device 6, when the external environment is extremely cold, if the air source heat pump 7 is used, the water generated by the compressed air in the heat generation process of the air source heat pump 7 has no time to be discharged from the air source heat pump 7, and has already frozen inside the air source heat pump 7, making the air source heat pump 7 itself and the pipeline for conveying domestic water extremely easy to damage. Therefore, the auxiliary electric heating device 6 should be used for auxiliary heating in extremely cold weather. This design increases the adaptability of the system to the environment while reducing the consumption of electric energy as much as possible, thereby saving costs.

[0043] Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An enhanced heating system based on a cascade heat storage device, characterized in that: It comprises a phase change heat storage device (1) and a water tank (2) arranged indoors, and a solar heat collector (3) arranged outdoors, wherein the solar heat collector (3) is connected to both ends of a heat charging pipe (9) of the phase change heat storage device (1) through pipelines, and the water tank (2) is connected to a heat releasing pipe (10) of the phase change heat storage device (1) through pipelines; The heat charging tube (9) is approximately a heart-shaped structure; The water tank (2) is connected to a domestic water inlet (4) and a heat user-side outlet (5), and an auxiliary electric heating device (6) is provided in the water tank (2).

2. The enhanced heating system based on the cascade heat storage device according to claim 1, characterized in that: The phase change heat storage device (1) is filled with a phase change material (11), and the phase change material (11) is composed of three materials, namely lauric acid, Mg(NO3)2·6(H2O)NH4NO3 and paraffin.

3. The enhanced heating system based on the cascade heat storage device according to claim 1, characterized in that: The heat charging pipe (9) is located below the heat releasing pipe (10).

4. The enhanced heating system based on the cascade heat storage device according to claim 1, characterized in that: The liquid flow directions in the heat charging tube (9) and the heat releasing tube (10) are opposite.

5. The enhanced heating system based on the cascade heat storage device according to claim 1, characterized in that: The outlet end of the heat release pipe (10) is connected to the upper part of the water tank (2) through a pipeline, and the inlet end is connected to the lower part of the water tank (2) through a pipeline; The domestic water inlet (4) is in communication with the lower part of the water tank (2), and the heat user-side outlet (5) is in communication with the upper part of the water tank (2).

6. The enhanced heating system based on the cascade heat storage device according to claim 1, characterized in that: A radiator (8) is provided on a pipeline connecting the outlet of the heat charging pipe (9) and the solar heat collector (3).

7. The enhanced heating system based on the cascade heat storage device according to claim 1, characterized in that: It also includes an air source heat pump (7) connected to the water tank (2).

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