A heat storage heat exchanger and solar energy system thereof

Abstract

The present invention provides a thermal storage heat exchanger comprising a housing, a thermal storage material disposed within the housing, a heat source pipe passing through the thermal storage material, and a plurality of modules arranged along the direction of heat source flow. Each module has a different thermal storage capacity, and the thermal storage capacity of the thermal storage material in each module increases along the direction of heat source flow. The novel thermal storage heat exchanger designed by the present invention ensures uniform heat storage and exchange, improving both heat storage and heat exchange capabilities.

Description

Technical Field

[0001] The present invention relates to a heat storage heat exchanger, in particular to a solar energy system with the heat storage heat exchanger. Background Art

[0002] Vigorously developing solar energy and the reuse of waste heat and other energy sources is an effective way to reduce fossil energy consumption. However, these energy sources have low energy density, intermittent use, and poor matching of supply and demand, making them ineffective as stable heat sources. Therefore, thermal storage is necessary to capture this energy first, thereby aligning energy supply and demand in terms of time and intensity.

[0003] In the field of energy utilization, when there is a temporal and spatial mismatch between energy supply and energy consumption, energy storage technology is required. Among various energy storage technologies, thermal storage technology is the most widely used technical branch. Based on the different heat storage temperatures, thermal storage technologies can be roughly divided into low-temperature thermal storage and medium- and high-temperature thermal storage. Low-temperature thermal storage is mainly aimed at fields such as solar thermal utilization and building energy conservation, and usually uses phase change materials such as salt solutions, hydrated salts, paraffin, and fatty acids as heat storage media; medium- and high-temperature thermal storage is widely used in fields such as solar thermal power generation, industrial waste heat utilization, nuclear power, and grid energy storage, and mainly uses thermal oil, molten salt, and high-temperature resistant solid materials as heat storage media. Among various medium- and high-temperature thermal storage technologies, solid thermal storage has many advantages such as high heat storage temperature, simple structure, and low cost. It is currently the most widely used thermal storage technology in actual projects. Thermal storage electric boiler technology using solid thermal storage materials has become an important technical choice for "non-coal heating."

[0004] Solar energy is an inexhaustible clean energy source with huge resources. The total amount of solar radiation energy received by the earth’s surface each year is 1×10 18 kW·h, more than 10,000 times the world's total annual energy consumption. However, the low energy density of solar radiation reaching the Earth (approximately 1 kilowatt per square meter) and its discontinuous nature present certain difficulties for large-scale development and utilization. Therefore, in order to widely utilize solar energy, not only must technical challenges be addressed, but it must also be economically competitive with conventional energy sources.

[0005] For excess solar energy, heat can be stored by heat storage, and heat storage operations can be performed according to different situations.

[0006] Current heat storage heat exchangers all use a single heat storage material, without considering the uniformity of heat exchange and heat storage during the heat storage and heat exchange process, resulting in insufficient heat storage and heat exchange capacity. To address these needs, the present invention provides improvements that ensure fully uniform heat storage and heat exchange. Summary of the Invention

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A heat storage heat exchanger includes a shell, a heat storage material is arranged in the shell, and the heat source pipeline passes through the heat storage material. It is characterized in that the heat storage material is divided into multiple modules along the flow direction of the heat source, the heat storage capacity of the heat storage material in each module is different, and the heat storage capacity of the heat storage material in different modules increases continuously along the flow direction of the heat source.

[0009] As an improvement, the heat storage material is a phase change material, and the melting point of the heat storage material of different modules gradually increases along the flow direction of the heat source.

[0010] As an improvement, the density of the heat storage materials of different modules increases continuously along the flow direction of the heat source.

[0011] As an improvement, the heat source pipeline is a bent structure.

[0012] As an improvement, the distribution density of the heat source pipelines in different modules is different. Along the flow direction of the heat source, the distribution density of the heat source pipelines in different modules becomes larger and larger.

[0013] As an improvement, the distribution density of the heat source pipelines in different modules is increasing more and more significantly along the flow direction of the heat source.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] By arranging the heat storage material to have different heat storage capacities along the flow direction of the heat source, the present invention ensures uniform heat storage throughout the entire process, preventing excessive heat storage at the front and insufficient heat storage at the back, thereby achieving uniform heat storage overall. During heat release, the flow direction of the cold fluid also gradually increases along the heat storage capacity, thereby improving heat storage and release capabilities and ensuring uniform heat exchange along the flow path. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the heat storage heat exchanger of the present invention;

[0017] Figure 2 It is a schematic structural diagram of the solar thermal collection system of the present invention. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0019] In this article, unless otherwise specified, “ / ” represents division, and “×” and “*” represent multiplication.

[0020] Figure 1The heat storage heat exchanger 4 of the present invention is disclosed. The heat exchanger includes a shell 41 in which a heat storage material 42 is arranged. The heat source pipe 43 passes through the heat storage material 42 to transfer heat in the fluid to the heat storage material.

[0021] like Figure 1 As shown, the heat storage material 42 is divided into a plurality of modules along the flow direction of the heat source, for example, Figure 1 As shown, it is divided into four modules. The heat storage capacity of the heat storage material 42 of each module is different. The heat storage capacity of the heat storage material of different modules increases continuously along the flow direction of the heat source.

[0022] By configuring the heat storage material to have different heat storage capacities along the direction of heat source flow, the present invention ensures uniform heat storage overall, preventing excessive heat storage at the front and insufficient heat storage at the back, thus achieving uniform heat storage overall. During heat storage and release, the cold fluid also flows in the direction of increasing heat storage capacity, thereby improving heat storage and release capacity and ensuring uniform heat exchange along the flow path.

[0023] As an improvement, the thermal storage material is a phase change material. Along the flow direction of the heat source, the melting point of the thermal storage material in different modules gradually increases. As the melting point gradually increases, the thermal storage capacity of the thermal storage material gradually increases.

[0024] As an improvement, the density of the thermal storage materials in different modules is continuously increased along the flow direction of the heat source. As the density gradually increases, the thermal storage capacity of the thermal storage materials gradually increases.

[0025] As an improvement, the heat source pipeline is a bent structure.

[0026] As an improvement, the heat source pipes are distributed at different densities in different modules. Along the direction of heat flow, the distribution of heat source pipes in different modules increases. This variation in distribution density results in different heat storage capacities, ensuring that the heat storage capacity at the rear is greater than that at the front, ensuring uniform heat storage.

[0027] As an improvement, the distribution of heat source pipes in different modules is increasingly increased along the flow direction of the heat source, which can further ensure the uniform distribution of heat storage capacity.

[0028] Figure 2 A solar thermal collector system is disclosed. Figure 2 As shown, the solar main line 1, a first branch line 2 and a second branch line 3 are arranged in parallel with the main line. The hot fluid flowing in the solar main line 1 comes from the fluid heated in the solar thermal collector. The preferred fluid is water.

[0029] like Figure 2As shown, a plurality of heat accumulators 4 arranged in parallel are provided on the first branch pipeline 2, a heat accumulator valve 5 is provided on the inlet pipeline of each heat accumulator 4, a heat exchanger 6 is provided on the second branch pipeline, a heat exchanger valve 7 is provided on the second branch pipeline, an inlet valve 8 is provided on the inlet pipe of the main pipeline 1, an outlet valve 9 is provided on the outlet pipe, and a main valve 10 is provided on the pipeline in parallel with the main pipeline and the first branch pipeline. A temperature sensor is provided in the heat accumulator 4 for detecting the temperature of the heat storage material in the heat accumulator, and the controller controls the opening and closing of the corresponding heat accumulator valve 5 according to the detected temperature of the heat storage material.

[0030] Preferably, the heat accumulator 4 is the heat storage heat exchanger 4 described above.

[0031] Preferably, the inlet valve 8 and the outlet valve 9 are opened, and the main valve 10 is closed, and the fluid then enters the heat accumulator and the heat exchanger 6 .

[0032] Preferably, the inlet valve 8 and the outlet valve 9 are opened, the main valve 10 is closed, and at least a portion of the heat exchanger valve 7 and the heat accumulator valve is opened, so that the fluid can enter at least a portion of the heat accumulator and the heat exchanger for heat storage or heat exchange.

[0033] As an improvement, when the temperature of the heat storage material in the heat accumulator detected exceeds a predetermined value, it indicates that the heat accumulator has completed heat storage and cannot store heat again, and the corresponding heat accumulator valve 5 is closed; when the temperature of the heat storage material in the heat accumulator detected is lower than a predetermined value, it indicates that the heat accumulator can store heat, and the corresponding heat accumulator valve is opened.

[0034] The present invention provides multiple heat accumulators, each of which is equipped with a temperature sensor for detecting the temperature of the heat storage material. The heat storage condition of the heat accumulator is then determined according to the temperature of the heat storage material, and the heat accumulator valve is opened or closed in a targeted manner, thereby storing heat in the heat accumulator in a targeted manner, so that the heat accumulator that has completed heat storage stops storing heat in time and the heat is used for heat storage in other heat accumulators, thereby avoiding heat waste.

[0035] As an improvement, the controller controls the valves of some heat accumulators to open and the valves of other heat accumulators to close, allowing the fluid to enter one of the heat accumulators for heat storage; when heat storage in one of the heat accumulators is completed, the corresponding heat accumulator valve is closed, and the controller opens one of the valves of another part of the heat accumulators, allowing the hot fluid to enter one of the heat accumulators in the other part for heat storage.

[0036] The above operation can ensure that one part of the heat storage tank is fully charged first, and then the next heat storage tank is charged. It can ensure that when the heat is not sufficient, the heat storage in one part is satisfied first, avoid heat dispersion, and ensure that the stored heat can be fully exchanged.

[0037] As an improvement, the controller controls the opening of the heat exchanger valve and simultaneously adjusts the closing of some or all of the heat accumulator valves to ensure the operation of the heat exchanger. Preferably, a temperature sensor is provided to detect the output temperature of the heat exchanger cold source and, based on the output temperature, controls the opening or closing of some or all of the heat accumulator valves.

[0038] Through the above-mentioned control method, the present invention opens or closes one or more heat accumulators for heat storage operation according to the specific heat exchange conditions of the heat exchanger. It can store heat while meeting the heat exchange requirements of the heat exchanger, thereby achieving the dual requirements of heat storage and heat exchange.

[0039] As an improvement, when the detected output temperature of the heat exchanger's cold source is lower than a predetermined value, all heat accumulator valves are controlled to close, ensuring that all hot fluid enters the heat exchanger for heat exchange. When the detected output temperature of the heat exchanger's cold source is higher than a predetermined value, at least one heat accumulator valve is controlled to open to perform heat storage. Preferably, the heat exchanger valve opening is simultaneously controlled to decrease. The number of heat accumulator valves opened is controlled based on the decreased opening, ensuring that the amount of fluid entering the heat accumulator corresponds to the decreased amount of fluid entering the heat exchanger.

[0040] As an improvement, a valve is provided at the collector outlet, and a temperature sensor is provided in the collector to detect the temperature of the fluid heated in the heater. When the detected temperature of the fluid in the collector falls below a predetermined value, the controller controls the main line valve to open, the main line inlet valve 8 and outlet valve 9 to close, the heat exchanger valve to open, and at least some of the heat accumulator valves to open, thereby forming a loop between the heat accumulator and the heat exchanger. The present invention can also intelligently realize the circulation of the heat accumulator and the heat exchanger pipeline according to the heat collection situation of the solar thermal collector, thereby ensuring the normal operation of the heat exchanger.

[0041] As an improvement, during heat release, the cold fluid also flows in the direction of increasing heat storage capacity, that is, in the same direction as the hot fluid that is storing heat. This improves the heat storage and release capacity and ensures uniform heat transfer along the flow path.

[0042] As an improvement, the controller opens some of the regenerator valves while closing others. When the temperature of the thermal storage material in a particular regenerator falls below a set value, the corresponding valve closes while simultaneously opening one of the other valves to store heat. This ensures the heat exchanger operates normally, preventing the initial high output temperature from being caused by both regenerators being open.

[0043] As an improvement, the heat exchanger is a shell and tube heat exchanger.

[0044] As an improvement, a baffle 11 is provided in the tube of the heat exchanger.

[0045] As an improvement, the shell and tube heat exchanger is a horizontal shell and tube heat exchanger.

[0046] As an improvement, the hot fluid flows through the tube side and the cold fluid flows through the shell side.

[0047] As an improvement, the shell side and the tube side are countercurrent flows. Along the flow direction of the fluid in the tube side, the spacing of the baffles increases continuously from the tube side inlet to the middle of the tube side. Then, from the middle of the tube side to the tube side outlet, the spacing of the baffles decreases continuously. Because in the countercurrent process, the heat exchange rate of the shell side and the tube side per unit length along the flow process of the fluid is relatively uniform, which makes the overall heat exchange effect the best. However, in experiments and simulations, it was found that the heat exchange rate in the middle is significantly greater than the heat exchange rate at the tube side inlet and outlet. Therefore, by changing the spacing of the baffles, the heat exchange area between the tube side fluid and the shell side fluid source in the baffles also changes. Therefore, the uneven heat exchange rate is compensated by the change in area, thereby further improving the heat exchange efficiency.

[0048] As an improvement, along the flow direction of the fluid within the tube, the spacing between the baffles increases in magnitude from the tube inlet to the middle of the tube. Then, from the middle of the tube to the tube outlet, the spacing between the baffles decreases in magnitude. This variation in magnitude makes the heat transfer per unit length of the entire fluid flow more uniform, further improving heat transfer efficiency.

[0049] The fluid in the shell side is gas. The baffles include multiple groups, each group of baffles including a lower baffle located at the lower portion of the shell and a upper baffle located at the upper portion of the shell; along the flow direction of the gas in the shell side, the ratio of the area of ​​the lower baffles to the area of ​​the upper baffles in different groups of baffles gradually decreases.

[0050] During the research process, it was found that the heat exchange of the baffles of the traditional heat exchanger is uneven in the cross section in the direction of gas flow. As the distance from the inlet increases, the heat exchange effect of the upper part of the shell becomes better and better, while the heat exchange effect of the lower part of the shell becomes worse and worse. The main reason is that as the gas continues to flow. Because the gas density is small, the gas flows upward, which significantly increases the upper heat exchange gas, so it is necessary to design an improved heat exchange structure. In the present invention, along the flow direction of the gas, the area ratio of the area of ​​the lower baffle to the area of ​​the upper baffle in the baffle group changes. As the gas in the shell flows, it gradually moves closer to the center, so that the center of the fluid strengthens the heat exchange in the heat exchange tubes around the shell and tube, which changes the previous heat exchange method, enhances the heat exchange efficiency of different positions, makes the heat exchange uniform on the whole, and further achieves the purpose of enhanced heat transfer.

[0051] As an improvement, along the direction of gas flow in the shell side, the ratio of the area of ​​the lower baffle to the area of ​​the upper baffle in the baffle group is gradually reduced. By changing the above range, the overall heat exchange can be further uniformed, further achieving the purpose of enhancing heat transfer.

[0052] Although the present invention has been disclosed above with reference to preferred embodiments, the present invention is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope defined by the claims.

Claims

1. A solar energy system, comprising a heat collector and a heat accumulator, wherein the fluid heated by the heat collector enters the heat accumulator for heat storage, wherein the heat accumulator comprises a shell, wherein a heat storage material is arranged in the shell, and a heat source pipeline passes through the heat storage material, and the heat storage material is divided into a plurality of modules along the flow direction of the heat source, and the heat storage capacity of the heat storage material of each module is different, and the heat storage capacity of the heat storage material of different modules increases continuously along the flow direction of the heat source; the solar energy system comprises a main line, and a first branch line and a second branch line arranged in parallel with the main line, wherein a plurality of heat accumulators arranged in parallel are arranged on the first branch line, a heat storage valve is arranged on each heat accumulator inlet line, and a second branch line is arranged on the second branch line. A heat exchanger is arranged on the pipeline, a heat exchanger valve is arranged on the second branch pipeline, a main valve is arranged on the main pipeline, and a temperature sensor is arranged in the heat accumulator for detecting the temperature of the heat storage material in the heat accumulator. The controller controls the opening and closing of the corresponding heat accumulator valve according to the detected temperature of the heat storage material; the heat exchanger is a shell and tube heat exchanger, and baffles are arranged in the tube side of the heat exchanger. The fluid in the shell side is gas, and the baffles include multiple groups, each group of baffles includes a lower baffle located at the lower part of the tube shell and an upper baffle located at the upper part of the tube shell; along the flow direction of the gas in the shell side, the ratio of the area of ​​the lower baffle to the area of ​​the upper baffle in different groups of baffles gradually decreases.

2. The solar energy system according to claim 1, wherein: The heat storage material is a meltable material. Along the flow direction of the heat source, the melting point of the heat storage material of different modules gradually increases.

3. The solar energy system according to claim 1, wherein: Along the flow direction of the heat source, the density of the heat storage material in different modules increases continuously.

4. The solar energy system according to claim 1, wherein: The heat source pipeline is a bent structure.

5. The solar energy system according to claim 4, wherein: The distribution density of the heat source pipelines in different modules is different. Along the flow direction of the heat source, the distribution density of the heat source pipelines in different modules becomes larger and larger.

6. The solar energy system according to claim 5, wherein: Along the flow direction of the heat source, the distribution density of the heat source pipelines in different modules is increasing more and more significantly.

Images