A rhombic heat exchange tube and a shell-and-tube heat exchanger thereof
By improving the design of the rhomboid heat exchange tube structure and the horizontal shell-and-tube heat exchanger, the problem of low heat transfer efficiency of traditional shell-and-tube heat exchangers has been solved, achieving a more efficient heat exchange effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG UNIV
- Filing Date
- 2024-03-25
- Publication Date
- 2026-06-12
AI Technical Summary
Traditional shell-and-tube heat exchangers have low heat transfer efficiency, and existing methods to enhance heat transfer are not ideal and cannot effectively improve the heat transfer effect.
It adopts a rhomboid heat exchange tube structure, with upper and lower chambers, evaporation tubes and condenser tubes inside. The liquid evaporates rapidly in the upper chamber and returns to the lower chamber through the condenser tube, realizing rapid heat exchange between the inside and the cold source, and heat exchange between the outside and the heat source. Combined with the horizontal shell-and-tube heat exchanger and baffle design, the fluid flow is optimized to increase the heat exchange area and uniformity.
It significantly improves the heat exchange efficiency of the heat exchanger, increases the heat source distribution range and the heat exchange area of the cold source, and achieves a more uniform heat distribution and a higher heat transfer effect.
Smart Images
Figure CN120702249B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of heat exchange, and particularly relates to a rhomboid heat exchange tube and its shell-and-tube heat exchanger. Background Technology
[0002] Heat exchangers are indispensable equipment for heat exchange and transfer in chemical production processes. In fields such as petrochemicals, cryogenic refrigeration, air separation, and seawater desalination, it is often necessary to heat cryogenic fluids or cool high-temperature fluids, and to vaporize liquids into steam or condense steam into liquids. These processes are all closely related to heat transfer and can therefore be accomplished using heat exchangers.
[0003] Commonly used heat exchangers include shell-and-tube heat exchangers and plate heat exchangers. Traditional shell-and-tube heat exchangers mostly use smooth tubes. Compared with various new plate heat exchangers, this traditional type has many disadvantages, such as low heat transfer efficiency and large size. However, shell-and-tube heat exchangers also have many advantages, such as simple manufacturing, resistance to high temperature and pressure, and convenient maintenance. Therefore, it is urgent to develop a double-sided enhanced high-efficiency heat exchanger based on the traditional shell-and-tube heat exchanger. Currently, some high-efficiency heat exchangers based on smooth tubes have been developed in China, but their heat transfer enhancement effect is not ideal.
[0004] To date, traditional high-efficiency heat exchangers mostly employ a single method to enhance heat transfer. One approach is to use rough-surface heat exchange tubes, creating de-edging flow by modifying the wall surface shape to disrupt the boundary layer and improve heat transfer performance within it. Examples include grooved tubes, spiral grooved tubes, longitudinal grooved tubes, corrugated tubes, swirl tubes, and finned tubes. Another approach is to use far-wall turbulence elements, generating continuous eddies that, under the influence of centrifugal force, ensure thorough mixing of the fluid at the tube center and the fluid in the wall boundary layer. However, using a single method results in less than ideal heat transfer performance.
[0005] Existing technology CN113530628A describes a corrosion-resistant, dust-resistant, low-grade waste heat cascade recovery and utilization system in the field of heat recovery technology. It includes a primary evaporator, a secondary evaporator, hot flow piping, an ejector, an expander, a generator, a condenser, a circulating pump, and a working medium. The primary and secondary evaporators are connected via hot flow piping. The ejector is connected to both the primary and secondary evaporators. The expander is driven by the generator and connected to the ejector. The expander is also connected to the condenser, which is connected to the secondary evaporator. An expansion valve is installed between the two. Through the expansion valve, the evaporation pressure of the working medium in the secondary evaporator is reduced, allowing it to absorb heat and vaporize at a lower temperature. This enables the recovery of waste heat near or below the acid dew point, increasing the amount of waste heat recovered. Furthermore, the coupling mechanism between the primary and secondary loops, employing a cascade utilization method, increases the utilization rate of waste heat resources. However, the heat exchange tubes in the aforementioned heat pipe heat exchanger are pure heat pipes, and no fluid can flow through them, making fluid heating impossible.
[0006] Therefore, in order to address the above problems, the present invention provides a novel heat exchange tube structure that greatly improves the heat exchange effect. Summary of the Invention
[0007] This invention provides a novel structure for heat exchange tubes and heat exchangers, thereby solving the aforementioned technical problems.
[0008] To achieve the above objectives, the technical solution of the present invention is as follows:
[0009] A rhomboid heat exchange tube includes a rhomboid base tube, characterized in that the two opposite corners of the rhombus are located at the upper and lower parts, respectively; the base tube is provided with an upper cavity, a lower cavity, and an evaporator and a condenser connecting the upper and lower cavities, the upper cavity being located at the upper part of the base tube, the lower cavity being located at the lower part of the base tube, the evaporator connecting the upper and lower cavities at the middle position, and the condenser being arranged on both sides of the evaporator; a sealed vacuum space is formed between the upper cavity, the lower cavity, the evaporator, and the condenser, and the lower cavity is filled with liquid; after absorbing heat, the liquid evaporates along the evaporator, enters the upper cavity, and then returns to the lower cavity along the condenser; at least a portion of the evaporator, the condenser, and the upper cavity exchange heat with a cold source in the base tube.
[0010] As an improvement, the centerline of the evaporator tube passes through the center of the base tube.
[0011] As an improvement, the centerline of the condenser tube is parallel to the side of the rhombus.
[0012] As an improvement, the upper and lower cavities are rhomboid structures.
[0013] As an improvement, the line connecting the centers of the rhombuses in the upper and lower cavities passes through the center of the base tube.
[0014] As an improvement, the diameter of the evaporator tube is larger than that of the condenser tube.
[0015] As an improvement, the diameter of the evaporator tube is 2-3 times that of the condenser tube.
[0016] As an improvement, the evaporator tube is inserted into the upper cavity to a certain height.
[0017] As an improvement, the evaporator tube extends into the upper chamber by 30-50% of the upper chamber height.
[0018] A horizontal shell-and-tube heat exchanger includes heat exchange tubes, including the heat exchange tubes described above.
[0019] Compared with the prior art, the present invention has the following advantages:
[0020] This invention improves the heat exchanger tube structure by setting up upper and lower chambers, as well as steam and condenser tubes. This allows the liquid in the chambers to evaporate rapidly, filling the entire steam and condenser tubes with steam and the entire heat exchanger tube. The cold source inside the heat exchanger tube can quickly exchange heat with the steam inside, while simultaneously exchanging heat with a heat source outside the heat exchanger tube. The heat source is distributed throughout the entire heat exchanger tube, resulting in a wide heat source distribution range and a large heat exchange area with the cold source. At the same time, heat exchange occurs on the external heat exchanger tube. Both heat sources rapidly heat the cold source inside the heat exchanger tube, greatly improving the heat exchanger efficiency. Attached Figure Description
[0021] Figure 1 This is a shell-side cross-sectional view of a shell-and-tube heat exchanger;
[0022] Figure 2 This is a schematic diagram of the cross-sectional structure of the heat exchange tube of the present invention;
[0023] Figure 3 This is a schematic diagram of the improved heat exchanger tube cross-sectional structure of the present invention;
[0024] Figure 4 This is the present invention. Figure 1 A schematic diagram of the axial cross-section of the heat exchanger tube. Detailed Implementation
[0025] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0026] A shell-and-tube heat exchanger, such as Figure 1As shown, the shell-and-tube heat exchanger includes a shell 1, heat exchange tubes 8, a tube-side inlet pipe 9, a tube-side outlet pipe 10, a shell-side inlet pipe 2, and a shell-side outlet pipe 3. A heat exchange tube bundle consisting of multiple parallel heat exchange tubes 8 is connected to a front tube sheet 6 and a rear tube sheet 7. The front end of the front tube sheet 6 is connected to a front end cap 4, and the rear end of the rear tube sheet 7 is connected to a rear end cap 5. The tube-side outlet pipe 10 is located on the rear end cap 5. The tube-side inlet pipe 9 is located on the front end cap 4. The shell-side inlet pipe 2 and shell-side outlet pipe 3 are both located on the shell 4. The tube-side fluid enters through the tube-side inlet pipe 9, exchanges heat with the shell-side fluid through the heat exchange tubes, and exits through the tube-side outlet pipe 10. As an improvement, the heat exchange tubes are microchannel heat exchange tubes.
[0027] Figure 2-3 The present invention demonstrates an improved rhomboid heat exchange tube, comprising a rhomboid base tube 81. Two opposite corners of the rhombus are located at the top and bottom, forming an upper corner and a lower corner, respectively, while the remaining two opposite corners are located on the left and right sides, forming a left corner and a right corner. The base tube contains an upper cavity 82, a lower cavity 83, and an evaporator tube 84 and a condenser tube 85 connecting the upper and lower cavities. The upper cavity 82 is located at the top of the base tube 81, and the lower cavity 83 is located at the bottom of the base tube. The evaporator tube 84 connects the upper cavity 82 and the lower cavity 83 at a midpoint, and the condenser tubes 85 are arranged on both sides of the evaporator tube 84. A sealed vacuum space is formed between the upper cavity, the lower cavity, the evaporator tube, and the condenser tube. The lower cavity 83 is filled with liquid.
[0028] During heat exchange, the heat source in the shell side heats the heat exchange tubes 8, causing the liquid in the lower chamber of the heat exchange tubes to absorb heat, evaporate along the steam tubes, enter the upper chamber, and then return to the lower chamber along the condenser tubes. At least a portion of the steam tubes, condenser tubes, and upper chamber exchange heat with the fluid in the heat exchange tubes. Generally, the liquid or vapor-liquid mixture that has condensed after heat exchange flows downwards in the condenser tubes.
[0029] This invention improves the heat exchanger structure by setting up upper and lower chambers, as well as steam pipes and condenser pipes. This allows the liquid in the chambers to evaporate rapidly, filling the entire steam pipe and condenser pipe with steam, and thus the entire heat exchange tube. The cold source inside the heat exchange tube can quickly exchange heat with the steam inside, while simultaneously exchanging heat with a heat source outside the heat exchange tube. The heat source is distributed throughout the entire heat exchange tube, resulting in a wide heat source distribution range and a large heat exchange area with the cold source. At the same time, heat exchange occurs on the external heat exchange tube. Both heat sources rapidly heat the cold source inside the heat exchange tube, greatly improving the heat exchange efficiency of the heat exchanger.
[0030] As an improvement, such as Figure 2 As shown, the centerline of the evaporator tube passes through the center of the base tube. As an improvement, such as... Figure 2As shown, the centerline of the condenser tube is parallel to the side of the rhombus, thus creating a bent structure. This arrangement ensures that the heat is evenly distributed within the heat exchange tube, resulting in a more uniform overall heat exchange effect and improving heat transfer efficiency.
[0031] As an improvement, such as Figure 2 As shown, the upper and lower chambers have a rhomboid structure, with the upper chamber including the two sides at the top corner and the lower chamber including the two sides at the bottom corner. The lower part of the upper chamber bends downwards, and the upper part of the lower chamber bends upwards. This bend design allows for rapid liquid evaporation, achieving a suction effect.
[0032] As an improvement, the line connecting the centers of the upper and lower chambers passes through the center of the base tube 81. This arrangement allows for a more uniform distribution of heat within the heat exchange tube, resulting in a more consistent and efficient heat exchange.
[0033] As an improvement, the diameter of the evaporator tube is larger than that of the condenser tube, being 2-3 times the diameter of the condenser tube. By setting the evaporator tube diameter to be larger than that of the condenser tube, the flow resistance of the evaporator tube is lower than that of the condenser tube, which promotes the flow of steam from the evaporator tube into the condenser tube and down the condenser tube, thus promoting fluid circulation.
[0034] As an improvement, the angle between the upper and lower corners is greater than that between the left and right corners. This arrangement distributes the base pipes to both sides, allowing for full circulation in the riser and downcomer pipes and preventing the steam from failing to reach the upper part of the riser pipe due to the base pipes being too high.
[0035] As an improvement, such as Figure 3 As shown, the evaporator tube extends into the upper chamber to a certain height, which is 30-50% of the upper chamber's height. By raising it to a certain height, it is ensured that all evaporation enters the upper chamber, and the condensed liquid in the upper chamber is prevented from entering the evaporator tube.
[0036] As an improvement, such as Figure 3 As shown, multiple rows of condenser tubes are arranged around the center of the base tube, with the diameter of the condenser tubes decreasing as they are closer to the center. By setting the condenser tubes with smaller diameters closer to the center, the flow resistance in the condenser tubes near the evaporator tubes is increased, preventing steam from entering the condenser tubes and thus enhancing fluid circulation. As the distance from the center increases, steam becomes less likely to enter the condenser tubes, so the tube diameter increases to enhance heat transfer while preventing steam from entering the condenser tubes.
[0037] As an improvement, the closer to the center, the greater the variation in the diameter of the condenser tubes. This arrangement further prevents steam from entering the condenser tubes while simultaneously enhancing heat transfer.
[0038] As an improvement, the heat exchanger is a horizontal shell-and-tube heat exchanger. As an improvement, baffles are installed inside the tube side of the heat exchanger. The cold source flows through the tube side, and the heat source flows through the shell side. The shell and tube sides flow counter-currently. Along the flow direction of the fluid within the tube side, the spacing of the baffles continuously increases from the tube inlet to the middle of the tube side. Then, from the middle of the tube side to the tube outlet, the spacing of the baffles continuously decreases. Because the heat exchange per unit length along the fluid flow path is relatively uniform during the counter-current process, the overall heat exchange effect is optimal. However, experiments and simulations have shown that the heat exchange in the middle is significantly greater than that at the tube inlet and outlet. Therefore, by changing the baffle spacing, the heat exchange area between the tube-side fluid and the shell-side fluid source within the baffles also changes. This area change compensates for the unevenness of heat exchange, thereby further improving the heat exchange efficiency.
[0039] As an improvement, along the flow direction of the fluid within the tube, the spacing of the baffles increases progressively from the tube inlet to the middle of the tube. Then, from the middle of the tube to the tube outlet, the spacing of the baffles decreases progressively. This variation in spacing makes the heat transfer per unit length of the fluid flow more uniform, further improving heat transfer efficiency.
[0040] As an improvement, such as Figure 4 As shown, the upper and lower chambers extend along the axial direction of the heat exchange tube.
[0041] As an improvement, multiple rows of evaporator and condenser tubes are installed along the axial direction of the heat exchanger tubes (the direction of cold source flow inside the heat exchanger tubes), for example... Figure 4 The diagram shows multiple rows of evaporator tubes. Along the flow direction of the cold source, the diameters of the evaporator and condenser tubes increase. By gradually increasing the tube diameter, heat transfer is enhanced downstream, as the temperature rises with the continuous flow of cold source, and the heat exchange efficiency decreases. Increasing the tube diameter increases the heat transfer area, thus making the overall heat transfer more uniform along the flow direction of the cold source, achieving a counter-current-like heat transfer effect and enhancing heat transfer. Furthermore, increasing the tube diameter reduces the pressure along the fluid flow direction, causing more steam to move in the direction of fluid flow, relieving pressure at the front end, balancing the overall pressure, and increasing the heat transfer efficiency along the fluid flow direction, further enhancing the overall heat transfer uniformity and achieving a counter-current-like heat transfer effect, thus enhancing heat transfer.
[0042] Along the flow direction of the cold source, the diameters of the evaporator and condenser tubes increase significantly. This further achieves a heat exchange effect similar to counter-current flow, thereby enhancing heat transfer.
[0043] As an improvement, multiple rows of evaporator and condenser tubes are arranged along the axial direction of the heat exchanger tubes (the direction of cold source flow). Along the flow direction of the cold source, the distance between adjacent rows of evaporator tubes decreases, and the distance between adjacent rows of condenser tubes also decreases. This enhances heat transfer downstream, as the temperature increases and the heat transfer efficiency decreases as the cold source continues to flow. By increasing the distribution density and expanding the heat transfer area, the overall heat transfer becomes more uniform along the flow direction of the cold source, achieving a counter-current-like heat transfer effect and thus enhancing heat transfer. Furthermore, by increasing the density, the pressure decreases as the fluid flows, causing more steam to move in the direction of fluid flow, relieving pressure at the front end and balancing the overall pressure. The increased fluid distribution also increases the heat transfer efficiency along the flow direction, further enhancing the overall uniformity of heat transfer and achieving a counter-current-like heat transfer effect, thus enhancing heat transfer.
[0044] Along the flow direction of the cold source, the distance between adjacent rows of evaporator tubes decreases and increases progressively, while the distance between adjacent rows of condenser tubes decreases and increases progressively. This can further achieve a heat exchange effect similar to counter-current flow, thereby enhancing heat transfer.
[0045] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.
Claims
1. A horizontal shell-and-tube heat exchanger, comprising heat exchange tubes, the shell-and-tube heat exchanger including a shell, heat exchange tubes, tube-side inlet tube, tube-side outlet tube, shell-side inlet pipe, and shell-side outlet pipe; a heat exchange tube bundle composed of multiple parallel heat exchange tubes is connected to a front tube sheet and a rear tube sheet; the front end of the front tube sheet is connected to a front end cap, and the rear end of the rear tube sheet is connected to a rear end cap; the tube-side outlet tube is disposed on the rear end cap; the tube-side inlet tube is disposed on the front end cap; the shell-side inlet pipe and the shell-side outlet pipe are both disposed on the shell; the tube-side fluid enters from the tube-side inlet tube, exchanges heat with the shell-side fluid through the heat exchange tubes, and exits from the tube-side outlet tube, the tube-side fluid being a cold source; the heat exchange tubes include rhomboid base tubes, characterized in that, The two opposite corners of the rhombus are located at the top and bottom, respectively. The base tube contains an upper chamber, a lower chamber, and an evaporator and a condenser connecting the upper and lower chambers. The upper chamber is located at the top of the base tube, and the lower chamber is located at the bottom. The evaporator connects the upper and lower chambers in the middle, and the condenser is located on both sides of the evaporator. A sealed vacuum space is formed between the upper chamber, lower chamber, evaporator, and condenser. The lower chamber is filled with liquid. After absorbing heat, the liquid evaporates along the evaporator, enters the upper chamber, and then returns to the lower chamber along the condenser. At least a portion of the evaporator, condenser, and upper chamber exchange heat with a cold source within the base tube.
2. The horizontal shell-and-tube heat exchanger as described in claim 1, characterized in that, The centerline of the evaporator tube passes through the center of the base tube.
3. The horizontal shell-and-tube heat exchanger as described in claim 1, characterized in that, The centerline of the condenser tube is parallel to the side of the rhombus.
4. The horizontal shell-and-tube heat exchanger as described in claim 1, characterized in that, The upper and lower cavities have a rhomboid structure.
5. The horizontal shell-and-tube heat exchanger as described in claim 4, characterized in that, The line connecting the centers of the rhombuses in the upper and lower cavities passes through the center of the base tube.
6. The horizontal shell-and-tube heat exchanger as described in claim 1, characterized in that, The diameter of the evaporator tube is larger than that of the condenser tube.
7. The horizontal shell-and-tube heat exchanger as described in claim 6, characterized in that, The diameter of the evaporator tube is 2-3 times that of the condenser tube.
8. The horizontal shell-and-tube heat exchanger as described in claim 1, characterized in that, The evaporator tube extends to a certain height into the upper cavity.
9. The horizontal shell-and-tube heat exchanger as described in claim 8, characterized in that, The length of the evaporator tube extending into the upper chamber is 30-50% of the height of the upper chamber.