Multi-module shell-and-tube type phase change heat accumulator and system

Abstract

The invention provides a multi-module shell-and-tube type phase change heat accumulator and system. The phase change heat accumulator comprises a heat accumulator shell, heat exchange tubes, tube plates, deflection baffles and phase change materials, the multiple heat exchange tubes are arranged on the section of the heat accumulator shell, the heat exchange tubes are filled with the phase change materials in a sealed mode, and a fluid inlet and a fluid outlet are formed in the two sides of the heat accumulator shell respectively; the tube plates are located on the two sides in the heat accumulator shell respectively, the two sides of the heat exchange tubes are fixed to the tube plates respectively, the deflection baffles are arranged in the heat accumulator shell at equal intervals, and the heat exchange tubes penetrate through the multiple deflection baffles. The system comprises a shell-and-tube phase change heat accumulator group, an inlet flow control three-way valve, a bypass pipeline, an outlet temperature sensor and an outlet mixed fluid temperature sensor. Through series-parallel combination of a plurality of tube-shell type phase change heat accumulators with small-capacity modules, different heat capacity requirements are flexibly met, the modules of the system can be increased or decreased according to actual capacity requirements, and huge size and difficult installation caused by capacity increase of a single device are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal energy storage, and in particular to a multi-module shell and tube type phase change heat accumulator and system. Background Art

[0002] Thermal storage technology is widely used in the energy field. It can effectively reduce energy waste and overcome the intermittent and volatile nature of clean energy to a certain extent. It has become an important means to optimize energy utilization and improve energy efficiency. Among various thermal storage technologies, phase change thermal storage technology has received widespread attention due to its unique advantages. PCM (Phase Change Material) has the characteristics of high energy storage density, good thermal matching and flexible temperature control. It can store a large amount of latent heat when absorbing and releasing heat through the phase change process, significantly improving the thermal storage efficiency. Based on this characteristic, phase change thermal storage technology has gradually been applied to industrial production, building heating and hot water supply. In the scenario of large-capacity hot water demand, phase change thermal storage technology can convert electrical energy into thermal energy storage during the off-peak electricity price period, and release heat during the peak electricity consumption period, so as to achieve the purpose of shifting peaks and filling valleys, which helps to reduce energy costs and balance the power load, and meet the continuous and stable hot water supply demand.

[0003] Shell and tube phase change heat accumulators can be widely used in large-capacity hot water heat storage systems due to their compact structure and efficient heat transfer performance. Heat accumulators of this design often encapsulate phase change materials in tubes or shells, and isolate phase change materials from heat transfer fluids through heat exchange tubes to achieve efficient heat exchange. During the process of charging and discharging heat, the phase change material absorbs or releases heat to the water flowing through it to meet the demand for continuous hot water supply. The shell and tube phase change heat accumulator structure can not only achieve efficient heat storage in a limited volume, but also is suitable for application scenarios with high heat transfer efficiency requirements. Therefore, it is widely used in industrial and commercial large-capacity hot water systems and becomes an ideal heat storage solution. However, in the scenario of large-capacity hot water demand, traditional single-type large-capacity heat accumulators have many shortcomings, such as large size, high manufacturing cost and difficulty in flexible expansion. At the same time, in view of temperature control requirements, the temperature control accuracy of existing large-capacity phase change heat storage systems is insufficient to meet the variable hot water demand under complex working conditions. Therefore, it is of great significance to develop a multi-module series-parallel shell and tube phase change heat storage system suitable for large-capacity hot water demand scenarios.

[0004] The prior art discloses a shell and tube heat storage and heating device, which mainly includes a shell, a heat storage device and a plurality of heating structures. The shell is a cylindrical closed structure, and the shell is provided with an inlet and an outlet connected to its inner cavity; the heat storage device is located in the shell, and comprises a plurality of PCM tubes evenly distributed on the cross section of the shell, and each PCM tube is arranged parallel and spaced along the axial direction of the shell, and the spacing between adjacent PCM tubes is equal to the spacing between the PCM tube and the inner wall of the shell; the PCM tube is filled with phase change material. A plurality of heating structures are respectively arranged on the outside of the PCM tube, and are used to heat the phase change material in the PCM tube to realize the heat storage function. The shell and tube heat storage and heating device of this structure increases the contact area between the fluid and the PCM tube, so that the heat transfer of the PCM tube is improved and the heat loss is reduced.

[0005] The disadvantages of the shell and tube heat storage heating device in the above-mentioned prior art include: the heat accumulator adopts a single structure. When used in a large-capacity hot water supply system, the required shell and tube phase change heat accumulator will be extremely large, with high processing and manufacturing difficulties, and relatively high transportation and installation costs; at the same time, due to the integrated design of the structure, the single heat accumulator is inconvenient to maintain and repair in actual operation, and the operating reliability of the system is greatly affected. In addition, the capacity of the heat accumulator with a single structure is fixed, and it is difficult to flexibly adjust the scale of heat storage or release according to specific needs, and it lacks scalability; under different hot water demand conditions, a single large-capacity heat accumulator is difficult to flexibly configure, and the system has poor adaptability. Summary of the invention

[0006] The embodiments of the present invention provide a multi-module shell and tube phase change heat accumulator and a system to effectively improve the working efficiency of the shell and tube phase change heat accumulator.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme.

[0008] According to one aspect of the present invention, a multi-module shell and tube phase change heat accumulator is provided, comprising: a heat accumulator shell, heat exchange tubes, tube sheets, baffles and phase change material, a plurality of heat exchange tubes are arranged on the cross section of the heat accumulator shell, the heat accumulator shell and the heat exchange tubes are both horizontally axially placed, the heat exchange tubes are arranged in a chamfered triangle shape on the cross section of the heat accumulator shell, adjacent heat exchange tubes are spaced equally, the phase change material is sealed and filled in the heat exchange tubes, a fluid inlet and a fluid outlet are respectively arranged on both sides of the heat accumulator shell; the tube sheets are respectively located on both sides of the heat accumulator shell, the heat exchange tubes are respectively fixed on the tube sheets on both sides, the baffles are equidistantly arranged in the heat accumulator shell, and the heat exchange tubes pass through a plurality of baffles.

[0009] Preferably, an automatic exhaust valve is provided at the upper end of the heat accumulator shell, and a drain valve is provided at the lower end.

[0010] Preferably, a head is provided at both ends of the heat accumulator, one side of the head is welded to the heat accumulator shell, and the other side of the head is connected to the heat accumulator shell by a flange, and the head is detachable.

[0011] Preferably, each of the heat exchange tubes is provided with a pull ring at one end close to the detachable seal head, and the heat exchange tube can be pulled out of the heat accumulator core through the pull ring.

[0012] Preferably, the tube sheet and the deflector baffle are installed in the heat accumulator shell by welding or mechanical fixing.

[0013] According to one aspect of the present invention, there is provided a phase change heat storage system based on the multi-module shell and tube phase change heat storage device, comprising a shell and tube phase change heat storage device group, an inlet flow control three-way valve, a bypass pipeline, an outlet temperature sensor and an outlet mixed fluid temperature sensor, wherein the shell and tube phase change heat storage device group comprises at least two shell and tube phase change heat storage devices;

[0014] The bypass pipeline is arranged in parallel with the shell and tube phase change heat storage group, the inlet flow control three-way valve is arranged at the flow inlet of the phase change heat storage system, one flow channel of the inlet flow control three-way valve is connected to the bypass pipeline, and the other flow channel is connected to the shell and tube phase change heat storage group, and the inlet flow control three-way valve divides the input flow of the phase change heat storage system into two parts, one part of the flow enters the bypass pipeline, and the other part of the flow enters the shell and tube phase change heat storage group;

[0015] The outlet temperature sensor is arranged at the output channel of the shell and tube phase change heat accumulator group to measure the temperature of the outlet fluid after passing through the shell and tube phase change heat accumulator group. The outlet mixed fluid temperature sensor is arranged at the merging pipe of the output channel of the shell and tube phase change heat accumulator group and the bypass pipe to measure the fluid temperature after the output fluid of the shell and tube phase change heat accumulator group and the output fluid of the bypass pipe are mixed.

[0016] Preferably, each multi-module shell and tube phase change heat storage device is connected in series to form a multi-module series shell and tube phase change heat storage system; or, each multi-module shell and tube phase change heat storage device is connected in parallel to form a multi-module parallel shell and tube phase change heat storage system; or, each multi-module shell and tube phase change heat storage device is connected in a mixed manner of series and parallel to form a multi-module series-parallel shell and tube phase change heat storage system.

[0017] Preferably, in scenarios where a higher temperature difference is required, a multi-module series shell-and-tube phase-change heat storage system is selected, where the input and output flow rates of each multi-module shell-and-tube phase-change heat storage are the same, and the temperature is gradually increased or decreased;

[0018] In scenarios where a smaller temperature difference and a larger flow rate are required, a multi-module parallel shell-and-tube phase-change heat storage system is selected. The flow distribution of each multi-module shell-and-tube phase-change heat storage system is uniform.

[0019] In complex scenarios that require higher temperature differences and larger flow rates, a multi-module series-parallel shell and tube phase change thermal storage system is selected. The series part is used to increase the temperature, and the parallel part is used to meet large flow requirements.

[0020] Preferably, a stop valve is provided at the fluid inlet and the fluid outlet of each multi-module shell and tube phase change heat accumulator.

[0021] Preferably, the outlet temperature sensor and the outlet mixed fluid temperature sensor are connected to the inlet flow control three-way valve, and transmit the measured fluid temperatures to the inlet flow control three-way valve respectively;

[0022] A control unit is provided in the inlet flow control three-way valve. When heat release starts, a fluid with a temperature of T1 and a total flow of F enters the shell and tube phase change heat accumulator group. After passing through the shell and tube phase change heat accumulator group, the outlet temperature of the fluid measured by the outlet temperature sensor is T2, and the temperature of the mixed fluid after merging with the bypass pipeline measured by the outlet mixed fluid temperature sensor is T3. The outlet temperature sensor and the outlet mixed fluid temperature sensor transmit the temperature values ​​T2 and T3 to the control unit in the inlet flow control three-way valve respectively.

[0023] After receiving the temperature signal, the control unit calculates the flow rate F1 that needs to pass through the bypass pipe and the flow rate F2 that needs to pass through the shell and tube phase change heat storage group based on the law of conservation of heat, where the total flow rate F = F1 + F2, F1 (T3-T1) = (F-F1) (T2-T3)

[0024] F1=F(T2-T3) / (T2-T1); F2=F-F1

[0025] The control unit determines the flow distribution ratio, generates a control signal through a PID control algorithm, and adjusts the opening of the flow channel corresponding to the shell and tube phase change heat accumulator group and the bypass pipe according to the control signal. It can be seen from the technical solution provided by the above-mentioned embodiment of the present invention that the present invention flexibly meets different thermal capacity requirements through a series-parallel combination of shell and tube phase change heat accumulators of multiple smaller capacity modules. Compared with the design of a single heat storage module, the system can increase or decrease modules according to actual capacity requirements, adapt to different application scenarios, and avoid the bulky size and installation difficulties caused by increasing the capacity of a single device.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description, which will become obvious from the following description, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0028] Figure 1 A structural diagram of a multi-module shell and tube phase change heat accumulator provided in an embodiment of the present invention.

[0029] Figure 2 It is a cross-sectional view of a multi-module shell and tube phase change heat accumulator provided in an embodiment of the present invention.

[0030] Figure 3 It is a schematic diagram of the operation of a series phase change heat storage system based on a multi-module shell and tube phase change heat storage device according to the second embodiment.

[0031] Figure 4 It is a schematic diagram of the operation of a parallel phase change heat storage system based on a multi-module shell and tube phase change heat storage device according to the third embodiment.

[0032] Figure 5 This is a fluid outlet temperature diagram of the heat storage state of the phase change heat accumulator group connected in series of the multi-module shell and tube phase change heat accumulators of the second embodiment.

[0033] Figure 6 It is a heat storage state capacity diagram of a phase change heat accumulator group of multi-module shell and tube phase change heat accumulators connected in series according to the second embodiment.

[0034] Figure 7 This is a fluid outlet temperature diagram of a phase change heat accumulator group of multi-module shell and tube phase change heat accumulators connected in series in the second embodiment in a heat release state.

[0035] Figure 8 This is a fluid outlet temperature diagram of the heat storage state of the phase change heat accumulator group of multi-module shell and tube phase change heat accumulators connected in parallel in the third embodiment.

[0036] Fig. 9 It is a heat storage state capacity diagram of a phase change heat accumulator group of multi-module shell and tube phase change heat accumulators connected in parallel in Example 3.

[0037] Fig.10 This is a fluid outlet temperature diagram of the heat release state of the phase change heat accumulator group of multi-module shell and tube phase change heat accumulators connected in parallel in the third embodiment.

[0038] The meaning of each symbol in the accompanying drawings:

[0039] 1. Fluid inlet; 2. Fluid outlet; 3. Heat accumulator shell; 4. Tube sheet; 5. Heat exchange tube; 6. Baffle; 7. Head; 8. Pull ring; 9. Automatic exhaust valve; 10. Drain valve; 11. Phase change material; 12. Stop valve; 13. Inlet flow control three-way valve; 14. Bypass pipe; 15. Outlet temperature sensor; 16. Outlet mixed fluid temperature sensor. DETAILED DESCRIPTION

[0040] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0041] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, the "connection" or "coupling" used herein may include wireless connection or coupling. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items.

[0042] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0043] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention.

[0044] In view of the deficiencies pointed out in the above background, the embodiment of the present invention designs a series-parallel phase change heat storage system based on a multi-module shell and tube phase change heat storage unit. The system decomposes the large-capacity heat storage demand into multiple smaller-capacity shell and tube phase change heat storage units, and realizes flexible configuration of heat through series-parallel combination. Bypass pipes and flow controllers are designed in the system, and dynamic adjustment of the outlet water temperature is achieved through flow distribution and temperature monitoring to meet the requirements for stable temperature and continuous heating in large-capacity hot water demand scenarios.

[0045] A multi-module shell and tube phase change heat accumulator provided by the present invention comprises a heat accumulator shell, heat exchange tubes, tube sheets, baffles and phase change material, wherein the phase change material is sealed and filled in the heat exchange tubes, and a fluid inlet and a fluid outlet are respectively arranged on both sides of the heat accumulator shell; the heat accumulator shell and the heat exchange tubes are both horizontally axially placed, a plurality of heat exchange tubes are arranged on the cross section of the heat accumulator shell, the heat exchange tubes are arranged in a chamfered triangle shape on the cross section of the heat accumulator shell, and the spacing between adjacent heat exchange tubes is equal, the tube sheets are respectively located on both sides of the heat accumulator shell, and both sides of the heat exchange tubes are respectively fixed on the tube sheets, the baffles are equidistantly arranged in the heat accumulator shell, and the heat exchange tubes pass through a plurality of baffles.

[0046] The upper end of the heat accumulator shell is provided with an automatic exhaust valve, and the lower end is provided with a drain valve. The automatic exhaust valve is used to remove the gas accumulated in the heat accumulator to ensure that the fluid can fill the heat accumulator. When a shell and tube phase change heat accumulator has a problem, the fluid inflow and outflow of the shell and tube phase change heat accumulator can be closed by the stop valve first, and then the drain valve can be used to drain the fluid in the heat accumulator, which is convenient for maintenance or shutdown.

[0047] Sealing heads are respectively arranged at both ends of the heat accumulator, one side of the sealing head is welded to the heat accumulator shell, and the other side of the sealing head is connected to the heat accumulator shell by a flange, and the sealing heads can be disassembled.

[0048] Preferably, the heat accumulator shell material may be carbon steel, stainless steel, copper or the like.

[0049] Preferably, the heat exchange tube material can be a plastic material such as polyethylene tube, polypropylene tube, polyvinyl chloride tube, etc., or a metal material such as stainless steel tube, copper tube, aluminum tube, etc. Metal tubes can be used for high temperature environments, and plastic tubes can be used for medium and low temperature environments. The selection of tubes can be selected according to actual needs.

[0050] Preferably, each heat exchange tube is provided with a pull ring at one end close to the detachable head, through which the heat exchange tube can be pulled out from the heat accumulator core, so as to facilitate the inspection and maintenance of a single multi-module shell and tube phase change heat accumulator.

[0051] Preferably, the diameter of the heat exchange tube may be 10-100 mm, and the spacing between the heat exchange tubes may be 2-10 mm. Different tube diameters and tube spacings may be selected according to different requirements for heat storage capacity.

[0052] Preferably, the heat exchange tube can be selected from smooth round tubes, threaded tubes, corrugated tubes and elliptical tubes, etc. Smooth round tubes are suitable for conventional fluid heat exchange, with small flow resistance, simple structure and low manufacturing cost; threaded tubes increase fluid disturbance to improve heat exchange efficiency, and are suitable for applications with low flow rate, high temperature difference or need for enhanced flow; corrugated tubes have the advantages of enhancing heat exchange area and reducing the influence of thermal expansion, and are suitable for high temperature and high pressure fluids or fluids containing corrosive substances or sediments; elliptical tubes improve flow disturbance and heat exchange efficiency through special cross-sectional shapes, and are suitable for scenes with high flow rate or limited space.

[0053] Preferably, the tube sheet and the baffle can be installed in the heat accumulator shell by welding or mechanical fixing (such as bolts, clamps or latches), and the specific method to be selected depends on the actual needs. If the structure is required to be more stable to avoid displacement of the baffle during operation, thereby improving the heat exchange efficiency and the control of fluid flow, a welded design should be selected. If it is necessary to facilitate the cleaning, replacement or maintenance of the baffle, especially when frequent maintenance or adjustment according to different working conditions is required, a detachable design can be selected. This design can easily remove and replace the baffle through mechanical fixing, thereby improving the convenience of maintenance.

[0054] The embodiment of the present invention also provides a phase change heat storage system based on a multi-module shell and tube phase change heat storage device, including a shell and tube phase change heat storage device group, an inlet flow control three-way valve, a bypass pipe, an outlet temperature sensor, and an outlet mixed fluid temperature sensor, wherein the shell and tube phase change heat storage device group includes at least two shell and tube phase change heat storage devices. The shell and tube phase change heat storage devices are connected in series to form a multi-module series shell and tube phase change heat storage system; or the shell and tube phase change heat storage devices are connected in parallel to form a multi-module parallel shell and tube phase change heat storage system; or the shell and tube phase change heat storage devices are connected in series and in parallel to form a multi-module series-parallel shell and tube phase change heat storage system.

[0055] The series shell and tube phase change thermal storage system is mainly used in scenarios that require high temperature difference and precise temperature control: the series mode is suitable for scenarios with high requirements for temperature change. By connecting multiple heat storage modules in series, the fluid can pass through multiple heat exchangers, and each module releases heat in turn, thereby ensuring that the fluid temperature gradually increases or gradually cools down. This is very effective in hot water supply systems or industrial heat exchangers that require high precise temperature control. In addition, the series mode is suitable for scenarios where the heat load changes less, and the load of each module can be evenly distributed to gradually increase the fluid temperature. At the same time, in the case of limited space, the series configuration helps to save installation space and makes it easier to control the temperature gradient. In the series mode, the flow rate is constant, that is, the input and output flow rates of each module are the same, because the fluid flows through each heat storage module in turn. In the series connection, the input fluid can be water or other heat-carrying fluids. When the fluid enters the first heat storage module, the flow rate is ensured to be stable through the flow control device, and then enters each series module in turn, and then flows out of the last module in turn, and the temperature is gradually increased or decreased.

[0056] The parallel shell-and-tube phase change thermal storage system is mainly used in scenarios with large flow and small temperature change requirements: when the system requires a higher heat capacity output and has a higher tolerance for temperature fluctuations of the outlet fluid, a parallel mode can be selected. In a parallel system, each module processes relatively similar fluid flow, so the output temperature of each module varies little, which is suitable for scenarios with large flow requirements and small temperature changes. In addition, the parallel system is more flexible in the face of heat load fluctuations, and can adjust the start and stop of the module according to demand to accurately control the heat output. At the same time, if the system requires redundancy, even if some modules fail, the overall system can continue to operate, avoiding the failure of a single module affecting the stability of the entire system. In parallel mode, the distribution of fluids between multiple heat storage modules is usually uniform, and a flow control device (such as a flow valve or flow meter) can ensure equal distribution of the flow of each module. If there is uneven temperature or flow, fine flow distribution can be achieved by adjusting the control valve. In parallel connection, the input fluids of multiple heat storage modules usually come from the same fluid source, and the fluid entering each module as a heat source is the same fluid, which can be water or a heat-carrying liquid. The output fluid flow of each heat storage module is consistent and usually flows to the same outlet. After merging through the corresponding outlet pipes, it is transported to the user end (such as a heating system, industrial equipment, etc.).

[0057] The series-parallel shell-and-tube phase change thermal storage system is suitable for some more complex systems. In complex scenarios where a high temperature difference and a large flow rate are required, a multi-module series-parallel shell-and-tube phase change thermal storage system is selected. The selection of a series-parallel hybrid mode can combine the advantages of both: the series part is used to increase the temperature to ensure that the fluid is gradually heated up. The parallel part can be used to meet large flow requirements and provide higher thermal capacity through multiple parallel modules.

[0058] A stop valve is provided at the fluid inlet and fluid outlet of each multi-module shell and tube phase change heat accumulator, which can cut off the fluid input and output of the multi-module shell and tube phase change heat accumulator as needed.

[0059] The bypass pipeline is arranged in parallel with the shell and tube phase change heat accumulator group.

[0060] The above-mentioned inlet flow control three-way valve is arranged at the flow inlet of the phase change heat storage system. One flow channel of the inlet flow control three-way valve is connected to the bypass pipe, and the other flow channel is connected to the shell and tube phase change heat storage group. The above-mentioned inlet flow control three-way valve divides the input flow of the phase change heat storage system into two parts, one part of the flow enters the bypass pipe, and the other part of the flow enters the shell and tube phase change heat storage group. The above-mentioned inlet flow control three-way valve controls the flow ratio entering the multi-module shell and tube phase change heat storage device and the bypass pipe by adjusting the opening of each of its flow channels.

[0061] The above-mentioned outlet temperature sensor is arranged at the output channel of the shell and tube phase change heat accumulator group to measure and display the temperature of the outlet fluid after passing through the shell and tube phase change heat accumulator group.

[0062] The outlet mixed fluid temperature sensor is arranged at the merging pipe of the output channel of the shell and tube phase change heat accumulator group and the bypass pipe, and measures and displays the fluid temperature after the output fluid of the shell and tube phase change heat accumulator group and the output fluid of the bypass pipe are mixed. The outlet temperature sensor and the outlet mixed fluid temperature sensor are connected to the inlet flow control three-way valve, and the measured fluid temperatures are respectively transmitted to the inlet flow control three-way valve for adjusting the opening of the inlet flow control three-way valve.

[0063] Embodiment 1

[0064] The structure diagram of a multi-module shell and tube phase change heat storage device provided in this embodiment is as follows Figure 1 As shown, the cross-sectional diagram is Figure 2 As shown, it includes a heat accumulator shell 3, a head 7, and a heat exchange tube 5. The heat accumulator shell 3 adopts a long cylindrical structure, and the heads 7 are installed at both ends. Among them, the right head and the shell are welded to ensure the sealing under high-pressure operating conditions; the left head and the shell are connected by a flange. This design is convenient for subsequent maintenance and repair. When necessary, the flange can be easily removed and the heat exchange tube 5 can be taken out for inspection or replacement.

[0065] The heat exchange tubes 5 are arranged horizontally and axially inside the heat accumulator shell 3 and are evenly distributed on the cross section. The heat exchange tubes 5 are arranged in a chamfered triangle structure, and the spacing between each heat exchange tube 5 is consistent. This design can maximize the heat exchange efficiency while maintaining good fluid dynamic characteristics. The heat exchange tubes 5 are sealed and filled with phase change materials 11. These materials will undergo phase changes when absorbing or releasing heat, thereby achieving efficient energy storage.

[0066] The two ends of the heat exchange tube 5 are fixed on the tube sheet 4, which is located at the two ends inside the heat accumulator shell 3 to ensure structural stability and heat exchange efficiency. A plurality of equally spaced baffles 6 are installed inside the heat accumulator shell 3, and the heat exchange tube 5 passes through these baffles in parallel. The baffles 6 are used to guide the flow of the fluid to form a turbulent effect, thereby improving the heat exchange efficiency between the fluid and the heat exchange tube 5.

[0067] The heat accumulator shell 3 can be made of carbon steel, stainless steel or copper materials according to actual applications. These materials have good mechanical properties and corrosion resistance. The heat exchange tube 5 can be made of plastic (such as polyethylene, polypropylene, polyvinyl chloride) or metal (such as stainless steel, copper, aluminum). Metal materials are suitable for high-temperature applications, while plastic materials are more suitable for low-temperature applications.

[0068] The diameter of the heat exchange tube 5 can be 10-100 mm, and the spacing between the heat exchange tubes can be 2-10 mm. By changing the tube diameter and the tube spacing, the capacity, heat storage and release power and other performance indicators of a single shell and tube heat accumulator can be changed to meet variable usage requirements.

[0069] The upper and lower sides of the heat accumulator shell 3 are respectively provided with a fluid inlet 1 and a fluid outlet 2. When the hot fluid enters the heat accumulator shell 3 through the fluid inlet 1, it bypasses the heat exchange tube 5 under the guidance of the baffle 6. The heat of the hot fluid is transferred to the phase change material 11 through the heat exchange tube 5, causing the phase change material 11 to change from solid to liquid, storing thermal energy. When heat needs to be released, the colder fluid flows around the heat exchange tube 5, absorbs the heat released by the phase change material 11, and restores the phase change material 11 from liquid to solid. At the same time, the temperature of the fluid increases, and the fluid with increased temperature is transported to other parts through the fluid outlet 2.

[0070] Each of the heat exchange tubes 5 is provided with a pull ring 8 at one end close to the detachable head. Through the pull ring 8, the staff can easily pull the heat exchange tube 5 out of the heat accumulator shell 3 to realize convenient maintenance of the heat accumulator core. This design can extend the service life of the heat accumulator and reduce maintenance costs.

[0071] Embodiment 2:

[0072] Taking the series phase change heat storage system based on multi-module shell and tube phase change heat storage as an example, its structure and working principle are explained as follows:

[0073] Figure 3 Schematic diagram of the operation of the series phase change heat storage system based on multi-module shell and tube phase change heat storage in Example 2. Figure 3 As shown, a heat exchange tube with a diameter of 20mm is used to design a shell-and-tube phase-change heat accumulator with a heat storage capacity of 30kWh. A single shell-and-tube phase-change heat accumulator is 2m long. According to relevant design requirements, a heating device with a total capacity of 120kWh and a fluid flow rate of 5000L / h is required. It can heat water with an initial temperature of 50℃ to 65℃ within 5 hours in the heat storage state to complete heat storage; in the heat release state, starting from the initial temperature of 65℃, heat is released using 50℃ water, the heat release time is not less than 3 hours, and the outlet water temperature is always maintained above 54℃.

[0074] According to the design requirements, the total capacity of the device is large. If only a single heat storage device is designed, it will be extremely large and inconvenient to maintain. At the same time, the device has high requirements for heat storage time, heat release time and heat release temperature, that is, the heat storage and release power is required to be very high. Therefore, this case uses a series phase change heat storage system based on multi-module shell and tube phase change heat storage devices to carry out thermal design of the heating device, as follows.

[0075] (1) Design of a single multi-module shell and tube phase change heat accumulator: The 120 kWh capacity task is decomposed into four 30 kWh capacity tasks. The theoretical design capacity of a single multi-module shell and tube phase change heat accumulator is 30 kWh. According to the capacity calculation, the heat exchange tube diameter of a single multi-module shell and tube phase change heat accumulator is 20 mm, the number of tubes is 800, and the tube length is 1.5 m.

[0076] (2) Based on the series connection of multi-module shell and tube phase change heat accumulators: Considering that the heating time is long and the heating temperature is greater than 54°C, the heat exchange temperature difference can be larger by connecting multiple heat accumulators in series, and the heat exchange efficiency can be improved to meet the design requirements. Therefore, four 30kWh multi-module shell and tube phase change heat accumulators are connected in series to form a phase change heat accumulator group. The heat exchange time of the fluid passing into the shell and tube phase change heat accumulator group is long, and the heat can be transferred and fully utilized in multiple devices, thereby improving the heat exchange efficiency. At the same time, a stop valve 12 is installed before and after each multi-module shell and tube phase change heat accumulator to facilitate the maintenance of a single multi-module shell and tube phase change heat accumulator.

[0077] (3) A series phase-change heat storage system based on a multi-module shell and tube phase-change heat storage device: Since the heating device has clear requirements on the outlet water temperature under heat release conditions, a bypass pipe 12 is added to the entire phase-change heat storage device, and an inlet flow control three-way valve 11 is added at the inlet of the total fluid, an outlet temperature sensor 15 is added at the outlet of the multi-module shell and tube phase-change heat storage device group, and an outlet mixed fluid temperature sensor 16 is added at the fluid mixing point, finally forming a series phase-change heat storage system based on a multi-module shell and tube phase-change heat storage device. The working principle of the system is as follows: when 50°C water flows to the phase change heat accumulator with an initial temperature of 65°C, the initial heat release power is large, and the temperature of the fluid flowing out of the phase change heat accumulator is higher than 54°C. The outlet mixed fluid temperature sensor senses the outlet water temperature and converts the temperature signal into an electrical signal and feeds it back to the inlet flow control three-way valve at the front end of the heat accumulator to divert the fluid entering the phase change heat accumulator group, allowing part of the fluid to go through the bypass pipeline, and finally mix at the mixing water three-way valve of the outlet mixed fluid temperature sensor to ensure that the temperature after mixing is the target temperature of 54°C.

[0078] The heat storage state fluid outlet temperature diagram, heat storage state capacity diagram and heat release state fluid outlet temperature diagram of the phase change heat storage group of the multi-module shell and tube phase change heat storage of this embodiment are respectively as shown in Figure 5-7 As shown. Figure 5 It can be seen that the time for the series group based on the multi-module shell and tube phase change heat storage to fully store heat is less than 5 hours. Figure 6 It can be seen that the thermal storage capacity is 136.7kWh, which meets the capacity requirement of 120kWh. Figure 7 It can be seen that under the heat release condition, the time when the outlet fluid temperature is higher than 54°C is 3.25 hours, and the heat release time is greater than 3 hours.

[0079] In view of the requirement that the outlet temperature must be kept above 54°C during the heat release state, the current device takes about 3.25 hours to meet the standard without flow regulation. Although it meets the basic requirements, the margin is relatively small. By integrating the temperature control system into the device and adjusting the opening of the inlet flow control valve, the flow can be adjusted more accurately during the heat release process, and the excess heat released in the early stage can be effectively allocated to later use. Specifically, without flow regulation, the heat released by the device in 3.25 hours is 109.8kWh, and the power required to continuously meet the conditions of inlet water temperature of 50°C and outlet water temperature of 54°C is 23.23kW. Theoretical calculations show that after the introduction of flow control, the time to meet the outlet temperature control requirements can be extended to 4.72 hours, thereby improving the heat release performance and overall stability of the system.

[0080] Embodiment three:

[0081] Taking the parallel phase change heat storage system based on multi-module shell and tube phase change heat storage as an example, its structure and working principle are explained as follows:

[0082] Figure 4 Schematic diagram of the operation of the parallel phase change heat storage system based on multi-module shell and tube phase change heat storage device of the third embodiment. Figure 4 As shown in the figure, a heat exchange tube with a diameter of 20mm is used to design a shell-and-tube phase-change heat accumulator with a heat storage capacity of 60kWh. A single shell-and-tube phase-change heat accumulator is 4m long. According to the relevant design requirements, a heating device with a total capacity of 240kWh and a fluid flow rate of 20,000L / h is required. It can heat water with an initial temperature of 50℃ to 65℃ within 3 hours in the heat storage state to complete heat storage; in the heat release state, starting from the initial temperature of 65℃, 50℃ water is used to release heat, the heat release time is not less than 1 hour, and the outlet water temperature is always maintained above 54℃.

[0083] According to the design requirements, the total capacity of the device is large, the total flow rate of the heat exchange fluid is large, and the heat storage and release require high power. If only a single heat accumulator is designed, its pressure resistance performance is extremely high, and the device will be extremely large and inconvenient to maintain. Therefore, this case uses a parallel phase change heat storage system based on multi-module shell and tube phase change heat storage to perform thermal design on the heating device, as follows.

[0084] (1) Design of a single multi-module shell and tube phase change heat accumulator: The 240 kWh capacity task is decomposed into four 60 kWh capacity tasks. The theoretical design capacity of a single multi-module shell and tube phase change heat accumulator is 60 kWh. According to the capacity calculation, the heat exchange tube diameter of a single multi-module shell and tube phase change heat accumulator is 20 mm, the number of tubes is 800, and the tube length is 3 m.

[0085] (2) Based on the parallel connection of multi-module shell-and-tube phase-change heat accumulators: Considering the large total flow rate of the fluid, only one flow path will result in too large flow resistance of the phase-change heat accumulator. Therefore, four 60kWh multi-module shell-and-tube phase-change heat accumulators are connected in parallel to form a phase-change heat accumulator group, and the total flow rate entering the shell-and-tube phase-change heat accumulator group is divided into four. The flow rate entering a single multi-module shell-and-tube phase-change heat accumulator is reduced, and the flow resistance is greatly reduced. At the same time, a stop valve 12 is installed before and after each multi-module shell-and-tube phase-change heat accumulator to facilitate the maintenance of a single multi-module shell-and-tube phase-change heat accumulator.

[0086] (3) A parallel phase change heat storage system based on a multi-module shell and tube phase change heat storage device: Since the heating device has clear requirements on the outlet water temperature under heat release conditions, a bypass pipe 12 is added to the entire phase change heat storage device, and an inlet flow control three-way valve 11 is added at the inlet of the total fluid, an outlet temperature sensor 15 is added at the outlet of the multi-module shell and tube phase change heat storage device group, and an outlet mixed fluid temperature sensor 16 is added at the fluid mixing point, finally forming a parallel phase change heat storage system based on a multi-module shell and tube phase change heat storage device. The working principle of the system is as follows: when 50°C water flows to the phase change heat accumulator with an initial temperature of 65°C, the initial heat release power is large, and the temperature of the fluid flowing out of the phase change heat accumulator is higher than 54°C. The outlet mixed fluid temperature sensor senses the outlet water temperature and converts the temperature signal into an electrical signal and feeds it back to the inlet flow control three-way valve at the front end of the heat accumulator to divert the fluid entering the phase change heat accumulator group, allowing part of the fluid to go through the bypass pipeline and finally mix at the mixing water three-way valve of the outlet mixed fluid temperature sensor to ensure that the temperature after mixing is the target temperature of 54°C.

[0087] Figure 8-10 The figure shows the fluid outlet temperature and heat storage capacity in the heat storage state and the outlet temperature in the heat release state obtained by parallel connection without flow regulation in this embodiment. Figure 8 It can be seen that the time for the parallel group based on the multi-module shell and tube phase change heat storage to fully store heat is less than 3 hours. Fig. 9 It can be seen that the thermal storage capacity is 257.9kWh, which meets the capacity requirement of 240kWh. Fig.10 It can be seen that under the heat release condition, the time when the outlet fluid temperature is higher than 54°C is 1.08h, and the heat release time is greater than 1h.

[0088] In view of the requirement that the outlet temperature must be kept above 54°C during the heat release state, the current device takes about 1.08 hours to meet the standard without flow regulation. Although it meets the basic requirements, the margin is relatively small. By integrating the temperature control system into the device and adjusting the opening of the inlet flow control valve, the flow can be adjusted more accurately during the heat release process, and the excess heat released in the early stage can be effectively allocated to later use. Specifically, without flow regulation, the heat released by the device in 1.08 hours is 149.8kWh, and the power required to continuously meet the conditions of inlet water temperature of 50°C and outlet water temperature of 54°C is 92.93kW. Theoretical calculations show that after the introduction of flow control, the time to meet the outlet temperature control requirements can be extended to 1.61 hours, thereby improving the heat release performance and overall stability of the system.

[0089] Embodiment 4:

[0090] This embodiment describes a method for regulating a temperature control system in a series-parallel phase-change thermal storage system under a heat release state based on a multi-module shell-and-tube phase-change thermal storage system. The specific steps are as follows:

[0091] Step 1: Signal acquisition and transmission

[0092] Set up a control unit in the inlet flow control three-way valve

[0093] At the beginning of heat release, the fluid with a temperature of T1 and a total flow rate of F completely enters the shell and tube phase change heat accumulator group. After passing through the shell and tube phase change heat accumulator, the fluid outlet temperature is T2. The mixed fluid temperature sensor at the outlet senses a mixed fluid temperature of T3, and converts the real-time sensed temperature signal into an electrical signal and transmits it to the control unit. The control unit is usually a PLC (Programmable Logic Controller) or a DCS (Distributed Control System), which is responsible for receiving these electrical signals and performing subsequent processing.

[0094] Step 2: Flow distribution calculation and adjustment

[0095] After receiving the temperature signal, the control unit calculates the flow distribution ratio based on the law of conservation of heat. The controller uses real-time temperature information and flow information to calculate the flow F1 that needs to pass through the bypass pipe and the flow F2 that needs to pass through the shell and tube phase change heat storage group, where the total flow F = F1 + F2. The control unit uses the following formula for calculation: F1 (T3-T1) = F2 (T2-T3), F1 = F-F2

[0096] F1(T3-T1)=(F-F1)(T2-T3)

[0097] F1=F(T2-T3) / (T2-T1)

[0098] Through this calculation, the control unit determines the flow distribution ratio, and then generates a control signal according to the flow distribution ratio through a PID (proportional (P), integral (I) and differential (D)) control algorithm.

[0099] Step 3: Three-way valve opening adjustment and temperature control

[0100] The control unit adjusts the opening of each flow channel of the inlet flow control three-way valve according to the control signal to distribute the flow of the fluid through the shell and tube phase change heat accumulator group and the bypass pipeline. The control unit monitors the temperature change of the system in real time through the PID control algorithm, and adjusts the valve opening according to the calculated flow distribution ratio. After the fluid is mixed through the shell and tube phase change heat accumulator group and the bypass pipeline, the outlet temperature reaches the target value T3. The entire process is completed by the control unit in a closed loop to ensure the stability of the system outlet temperature.

[0101] In this process, the control unit is the core control unit, which is responsible for receiving real-time data from the sensor, performing flow distribution calculations, and generating adjustment instructions through the PID control algorithm, and finally achieving precise adjustment of the opening of the flow control three-way valve. In this way, the system can adjust the flow distribution ratio in real time to ensure that the fluid temperature reaches the set target.

[0102] In summary, the multi-module shell and tube phase change heat accumulator of the embodiment of the present invention has strong independence, the phase change material is filled in the heat exchange tube, and when the phase change material fails, it is only necessary to pull out the heat exchange tube for replacement. At the same time, shut-off valves are provided in front and behind each module. Once a problem occurs in the device, the flow path can be cut off individually, which facilitates the inspection and replacement of a single module, avoids overall system shutdown, and improves the system operation stability.

[0103] The present invention combines multiple shell-and-tube phase-change heat storage devices with smaller capacity modules in series and parallel to flexibly meet different heat capacity requirements. Compared with the design of a single heat storage module, the system can increase or decrease modules according to actual capacity requirements, adapt to different application scenarios, and avoid the bulky volume and installation difficulties caused by increasing the capacity of a single device.

[0104] The design of the present invention adds a bypass pipe, a flow controller and a temperature sensor to achieve precise adjustment of the system's outlet water temperature. Compared with the traditional fixed temperature control structure, this design has higher temperature control flexibility, can dynamically adjust the temperature according to the demand for hot water, and ensure the stability and consistency of the output water temperature, which is particularly suitable for scenarios with large load fluctuations.

[0105] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0106] It can be known from the description of the above implementation methods that those skilled in the art can clearly understand that the present invention can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments of the present invention or certain parts of the embodiments.

[0107] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The device and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0108] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A multi-module shell and tube phase change heat storage device, characterized in that: include: A heat accumulator shell, heat exchange tubes, tube sheets, baffles and phase change materials. A plurality of heat exchange tubes are arranged on the cross section of the heat accumulator shell. The heat accumulator shell and the heat exchange tubes are both horizontally axially placed. The heat exchange tubes are arranged in a chamfered triangle on the cross section of the heat accumulator shell. The spacing between adjacent heat exchange tubes is equal. The phase change material is sealed and filled in the heat exchange tubes. A fluid inlet and a fluid outlet are respectively arranged on both sides of the heat accumulator shell. The tube sheets are respectively located on both sides of the heat accumulator shell. Both sides of the heat exchange tubes are respectively fixed on the tube sheets. The baffles are equidistantly arranged in the heat accumulator shell. The heat exchange tubes pass through a plurality of baffles.

2. The multi-module shell and tube phase change heat storage device according to claim 1, characterized in that: An automatic exhaust valve is arranged at the upper end of the heat accumulator shell, and a drain valve is arranged at the lower end.

3. The multi-module shell and tube phase change heat storage device according to claim 1, characterized in that: Sealing heads are respectively arranged at both ends of the heat accumulator, one side of the sealing head is welded to the heat accumulator shell, and the other side of the sealing head is connected to the heat accumulator shell by a flange, and the sealing heads can be disassembled.

4. The multi-module shell and tube phase change heat storage device according to claim 1, characterized in that: Each heat exchange tube is provided with a pull ring at one end close to the detachable sealing head, and the heat exchange tube can be drawn out from the heat accumulator core through the pull ring.

5. The multi-module shell and tube phase change heat storage device according to claim 1, characterized in that: The tube sheet and the baffle are installed in the heat accumulator shell by welding or mechanical fixing.

6. A phase change heat storage system based on the multi-module shell and tube phase change heat storage device according to any one of claims 1 to 5, comprising a shell and tube phase change heat storage device group, an inlet flow control three-way valve, a bypass pipeline, an outlet temperature sensor and an outlet mixed fluid temperature sensor, wherein the shell and tube phase change heat storage device group comprises at least two shell and tube phase change heat storage devices; The bypass pipeline is arranged in parallel with the shell and tube phase change heat storage group, the inlet flow control three-way valve is arranged at the flow inlet of the phase change heat storage system, one flow channel of the inlet flow control three-way valve is connected to the bypass pipeline, and the other flow channel is connected to the shell and tube phase change heat storage group, and the inlet flow control three-way valve divides the input flow of the phase change heat storage system into two parts, one part of the flow enters the bypass pipeline, and the other part of the flow enters the shell and tube phase change heat storage group; The outlet temperature sensor is arranged at the output channel of the shell and tube phase change heat accumulator group to measure the temperature of the outlet fluid after passing through the shell and tube phase change heat accumulator group. The outlet mixed fluid temperature sensor is arranged at the merging pipe of the output channel of the shell and tube phase change heat accumulator group and the bypass pipe to measure the fluid temperature after the output fluid of the shell and tube phase change heat accumulator group and the output fluid of the bypass pipe are mixed.

7. The phase change heat storage system of the multi-module shell and tube phase change heat storage device according to claim 5, characterized in that: The multi-module shell and tube phase change heat storage devices are connected in series to form a multi-module series shell and tube phase change heat storage system; or, the multi-module shell and tube phase change heat storage devices are connected in parallel to form a multi-module parallel shell and tube phase change heat storage system; or, the multi-module shell and tube phase change heat storage devices are connected in a mixed manner of series and parallel to form a multi-module series-parallel shell and tube phase change heat storage system.

8. The phase change heat storage system of the multi-module shell and tube phase change heat storage device according to claim 7, characterized in that: In scenarios where a higher temperature difference is required, a multi-module shell-and-tube phase-change thermal storage system is selected. The input and output flow rates of each multi-module shell-and-tube phase-change thermal storage system are the same, and the temperature is gradually increased or decreased. In scenarios where a smaller temperature difference and a larger flow rate are required, a multi-module parallel shell-and-tube phase-change heat storage system is selected. The flow distribution of each multi-module shell-and-tube phase-change heat storage system is uniform. In complex scenarios that require higher temperature differences and larger flow rates, a multi-module series-parallel shell and tube phase change thermal storage system is selected. The series part is used to increase the temperature, and the parallel part is used to meet large flow requirements.

9. The phase change heat storage system of the multi-module shell and tube phase change heat storage device according to claim 5, characterized in that: A stop valve is provided at the fluid inlet and the fluid outlet of each multi-module shell and tube phase change heat accumulator.

10. The phase change heat storage system of the multi-module shell and tube phase change heat storage device according to claim 5, characterized in that: The outlet temperature sensor and the outlet mixed fluid temperature sensor are connected to the inlet flow control three-way valve, and transmit the measured fluid temperatures to the inlet flow control three-way valve respectively; A control unit is provided in the inlet flow control three-way valve. When heat release starts, a fluid with a temperature of T1 and a total flow of F enters the shell and tube phase change heat accumulator group. After passing through the shell and tube phase change heat accumulator group, the outlet temperature of the fluid measured by the outlet temperature sensor is T2, and the temperature of the mixed fluid after merging with the bypass pipeline measured by the outlet mixed fluid temperature sensor is T3. The outlet temperature sensor and the outlet mixed fluid temperature sensor transmit the temperature values ​​T2 and T3 to the control unit in the inlet flow control three-way valve respectively. After receiving the temperature signal, the control unit calculates the flow rate F1 that needs to pass through the bypass pipe and the flow rate F2 that needs to pass through the shell and tube phase change heat storage group based on the law of conservation of heat, where the total flow rate F = F1 + F2, F1 (T3-T1) = (F-F1) (T2-T3) F1=F(T2-T3) / (T2-T1); F2=F-F1 The control unit determines the flow distribution ratio, generates a control signal through a PID control algorithm, and adjusts the opening of the flow channels corresponding to the shell and tube phase change heat storage device group and the bypass pipeline according to the control signal.

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