Temperature-limited nested heat pipe heat exchanger and method thereof

Abstract

The application discloses a temperature-limited nested heat pipe heat exchange device and a method thereof, which comprises a cold source heat pipe, a heat source heat pipe, and a nesting part. The cold source heat pipe is internally provided with a working medium one. The heat source heat pipe is internally provided with a working medium two. The nesting part is used for nested connection of the cold source heat pipe and the heat source heat pipe, and internally stores a heat-conducting fluid. When the heat-conducting fluid in the nesting part is different from the external temperature, the contact area of the inner wall of the heat-conducting fluid and the outer wall of the cold source heat pipe changes. The application has the beneficial effects that low-temperature corrosion caused by flue gas acid dew point is avoided, the service life and safe operation of the heat exchange equipment and the production system are ensured, the long service life of the equipment is realized, and the maximum waste heat recycling is realized.

Description

Technical Field

[0001] This invention relates to the field of waste energy recovery and energy saving, and in particular to a temperature-limited nested heat pipe heat exchange device and method. Background Technology

[0002] With economic development and intensified competition across all industries, manufacturing profits have decreased. Simultaneously, strict global controls on energy and emissions, including in China, have led individuals, businesses, and governments to place great emphasis on energy conservation and waste energy utilization. Currently, high-temperature flue gas and exhaust gases are generally recovered and ultimately emitted as low-temperature flue gas and exhaust gases. However, to prevent corrosion of equipment and systems due to excessively low temperatures after heat exchange, these low-temperature flue gases and exhaust gases must have their overall exhaust temperature increased. This results in higher energy consumption for businesses and factories, increased business expenditures, and increased energy consumption and emission intensity.

[0003] While recovering waste heat from low-temperature flue gas using conventional heat exchangers or heat pipes can generate considerable economic benefits, the lifespan of heat exchange equipment and flue systems is significantly shortened due to acid condensation and corrosion after heat exchange. This results in high maintenance costs and frequent replacements, and the flue gas may not be effectively vented and diluted, which is detrimental to residents' health. These issues limit the development of low-temperature flue gas waste heat recovery, necessitating the search for a safe heat exchange method to achieve energy savings and reduce carbon emissions for businesses and local governments. Summary of the Invention

[0004] In view of the above situation, there is an urgent need to find a safe way to exchange heat and prevent the flue gas from corroding equipment and systems due to excessively low temperature after heat exchange. The present invention provides a temperature-limited nested heat pipe heat exchange device and method.

[0005] The technical solution of the present invention:

[0006] A temperature-limited nested heat pipe heat exchanger includes:

[0007] A cold source heat pipe, wherein a working fluid is provided inside the cold source heat pipe;

[0008] Heat source heat pipe, wherein the heat source heat pipe is provided with working fluid II;

[0009] Nesting component, used for nesting and connecting the cold source heat pipe and the heat source heat pipe, and containing heat-conducting fluid inside;

[0010] When the temperature of the heat-conducting fluid inside the nested component is different from that of the outside, the contact area between the heat-conducting fluid and the outer wall of the cold source heat pipe changes.

[0011] Furthermore, the cold source heat pipe is positioned above the heat source heat pipe.

[0012] Furthermore, it also includes a positioning device for adjusting and keeping the center positions of the upper and lower heat pipes aligned.

[0013] Furthermore, the nested component is a π-shaped nested component.

[0014] Furthermore, the nesting element is disposed on the outer wall of the cold source heat pipe.

[0015] Furthermore, there is a gap between the nested component and the bottom of the cold source heat pipe.

[0016] Furthermore, the nesting component has a hole, the diameter of which is smaller at the top than at the bottom.

[0017] Furthermore, the lower part of the cold source heat pipe is provided with an evaporation section one, and the upper part of the heat source heat pipe is provided with a condensation section two.

[0018] Furthermore, the evaporation section one and the condensation section two overlap when the upper and lower heat pipes are nested, forming a heat exchanger.

[0019] A temperature-limited nested heat pipe heat exchange method, the method being based on a temperature-limited nested heat pipe heat exchange device, comprising:

[0020] When the ambient temperature is higher than the set temperature, the density of the heat transfer fluid is lower than the density of the working fluid in the cold source heat pipe. The working fluid in the cold source heat pipe compresses the heat transfer fluid, increasing the contact area between the heat transfer fluid and the cold source heat pipe. When the ambient temperature is lower than the set temperature, the density of the heat transfer fluid is higher than the density of the working fluid in the cold source heat pipe. The cold source heat pipe floats on the heat transfer fluid, and some of the heat transfer fluid flows to the bottom of the cold source heat pipe, reducing the contact area between the heat transfer fluid and the cold source heat pipe. When the ambient temperature equals the set temperature, the temperature of the heat transfer fluid, the heat pipe, and the ambient temperature are consistent, and they are in a state of temperature-limited equilibrium.

[0021] The beneficial effects of this invention are as follows:

[0022] This system avoids acid dew point in flue gas, preventing low-temperature corrosion of equipment and production systems, thus ensuring the service life and safe operation of heat exchange equipment and production systems. It automatically modifies the heat transfer coefficient and heat transfer capacity of low-temperature flue gas and exhaust gas, ensuring a significant reduction in heat transfer coefficient and heat transfer capacity when the temperature of flue gas and exhaust gas falls below a certain lower limit. This enables safe heat exchange and long-term operation under complex and variable flue gas and exhaust gas conditions. While achieving a long equipment lifespan, it also maximizes waste heat recovery and utilization. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of low heat transfer when nested dual heat pipes are below the set temperature.

[0024] Figure 2This is a schematic diagram of high heat transfer when nested dual heat pipes are at a heat source temperature higher than the set temperature.

[0025] Figure 3 This is a schematic diagram of low heat transfer in the second type of nested dual heat pipes when the heat source is below the set temperature.

[0026] Figure 4 This is a schematic diagram of the high heat transfer of the second type of nested double heat pipe when the heat source is above the set temperature.

[0027] The diagram is labeled as follows: 1-Heat source heat pipe; 2-Cold source heat pipe; 11-Condensing section one; 12-Insulation section one; 13-Evaporation section one; 21-Working fluid one; 30-Working fluid two; 31-Condensing section two; 32-Insulation section two; 33-Evaporation section two; 41-Heat transfer fluid; 42-Nested component; 44-Bottom ring. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the content of this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to this invention are shown in the accompanying drawings, not all of them.

[0029] A temperature-limited nested heat pipe heat exchange device includes a cold source heat pipe 2, a heat source heat pipe 1, and a nesting component 42. The cold source heat pipe 2 contains a working fluid 21, which can directly contact and exchange heat with the cold fluid in the outside. The heat source heat pipe 1 contains a working fluid 30, which can directly contact and exchange heat with the hot fluid (flue gas, exhaust gas) in the outside. The nesting component 42 is used to nest and connect the cold source heat pipe 2 and the heat source heat pipe 1, and contains a heat-conducting fluid 41 inside, which serves as an intermediate medium to realize the circulating heat exchange between the cold source heat pipe 2 and the heat source heat pipe 1. When the temperature of the heat-conducting fluid 41 inside the nesting component 42 is different from that of the outside (flue gas temperature), the contact area between the heat-conducting fluid 41 and the outer wall of the cold source heat pipe 2 changes. When the ambient temperature is higher than the set temperature, the hot flue gas flows through the evaporation section 33 of the heat source heat pipe 1, heating and evaporating the working fluid 30 into a gaseous state. The steam working fluid 30 exchanges heat with the heat transfer fluid 41, causing the temperature of the heat transfer fluid 41 to rise and its volume to increase. As a result, the heat transfer fluid 41 flows into space in other directions, increasing the contact area between the heat transfer fluid 41 and the outer wall of the cold source heat pipe 2. Some of the steam working fluid 30 is cooled and condensed into liquid as it passes through the condensation section 31, returning to the evaporation section 33 from the wall. The working fluid 21 is heated and evaporated into a gaseous state by the heat transfer fluid 41. The steam working fluid 21 reaches the condensation section 11 and is cooled and evaporated into a gaseous state. The fluid cools and condenses into liquid, returning from the wall to the evaporation section 13 to form a heat exchange cycle. When the ambient temperature is lower than the set temperature, the hot flue gas flows through the evaporation section 33 of the heat source heat pipe 1. The heat exchange cycle of the working fluid in the heat source heat pipe 1 is the same as at high temperatures, except that the internal evaporation flow rate is reduced. Because the temperature of the working fluid 30 is low, the temperature of the heat transfer fluid 41 is also low, causing the heat transfer fluid 41 to shrink in volume. Consequently, the contact area between the heat transfer fluid 41 and the outer wall of the cold source heat pipe 2 is reduced, and the working fluid circulation of the cold source heat pipe 2 is also reduced. When the ambient temperature equals the set temperature, the temperature of the heat transfer fluid 41 and the heat pipe are consistent, and they are in a temperature-limited equilibrium state. This heat exchange method avoids the formation of flue gas acid dew point and low-temperature corrosion, ensuring the service life and safe operation of the heat exchange equipment and production system.

[0030] Preferably, the cold source heat pipe 2 is positioned above the heat source heat pipe 1, which makes the heat exchange effect more stable.

[0031] Preferably, it also includes a positioning device for adjusting and keeping the center positions of the upper and lower heat pipes in a straight line, so as to keep the overall structure of the device stable.

[0032] Preferably, the nesting component 42 is a π-shaped nesting component, which is beneficial for nesting and connecting the cold source heat pipe 2 and the heat source heat pipe 1, making the device operate more stably; it also leaves enough space for the heat transfer fluid 41 to flow and exchange heat.

[0033] Preferably, the nesting member 42 is disposed on the outer wall of the cold source heat pipe 2. Preferably, there is a gap between the nesting member 42 and the bottom of the cold source heat pipe 2 to ensure that the heat-conducting fluid 41 has enough space to flow and exchange heat.

[0034] Preferably, the nesting member 42 is provided with a hole, the diameter of which is smaller at the top than at the bottom, to ensure the safety and stability of the device during heat exchange.

[0035] Preferably, the lower part of the cold source heat pipe 2 is provided with an evaporation section 13, and the upper part of the heat source heat pipe 1 is provided with a condensation section 31. Preferably, the evaporation section 13 and the condensation section 31 overlap when the upper and lower heat pipes are nested, forming a heat exchange zone, which is beneficial to the heat exchange cycle between the heat pipes.

[0036] A temperature-limited nested heat pipe heat exchange method, the method being based on a temperature-limited nested heat pipe heat exchange device, comprising:

[0037] The heat transfer fluid 41 exchanges heat with the outside environment. When the outside temperature is higher than the set temperature, the heat transfer fluid 41 is heated and evaporates, reducing its density. At this point, the density of the heat transfer fluid 41 is lower than the density of the working fluid 21 in the cold source heat pipe 2. The working fluid 21 in the cold source heat pipe 2 will sink, thus compressing the heat transfer fluid 41. This increases the contact area between the heat transfer fluid 41 and the cold source heat pipe 2, significantly improving its heat transfer coefficient and enhancing its heat exchange effect to achieve high efficiency. High-temperature heat transfer: When the ambient temperature is lower than the set temperature, the density of the heat transfer fluid 41 is higher than the density of the working fluid 21 in the cold source heat pipe 2. The cold source heat pipe 2 floats on the heat transfer fluid 41, and part of the heat transfer fluid 41 flows to the bottom of the cold source heat pipe 2, which reduces the contact area between the heat transfer fluid 41 and the cold source heat pipe 2, thereby reducing its heat transfer coefficient and its heat transfer effect, resulting in low heat transfer at low temperatures. When the ambient temperature is equal to the set temperature, the temperature of the heat transfer fluid 41, the heat pipe and the ambient temperature are consistent, and they are in a temperature-limited equilibrium state.

[0038] The following provides a more detailed description of the implementation of a temperature-limited nested heat pipe heat exchange device and method.

[0039] First Implementation Method

[0040] like Figure 1 and Figure 2 As shown, in this embodiment, the upper cold source heat pipe 2 is nested in the lower heat source heat pipe 1. The evaporation section 13 of the cold source heat pipe 2 and the condensation section 31 of the heat source heat pipe 1 overlap in height to form a heat exchange zone. In the middle is a small-sized thin layer of heat-conducting fluid 41, which is located in the nesting member 42. Considering the change in the relative position between the two heat pipes when the temperature changes, the center position of the two nested heat pipes is kept on a straight line by a locking device.

[0041] Assume the dew point temperature of the flue gas is 90℃, while the temperature of the cold fluid is 40℃; during heat exchange at a dew point temperature of 90℃, the temperature of the intermediate heat-conducting fluid 41 is 70℃.

[0042] When the flue gas temperature exceeds 90℃ (e.g., 100℃ or higher), the hot flue gas flows through the evaporation section 33 of the heat pipe at the bottom of the heat source heat pipe 1. Part of the working fluid 30 inside the heat source heat pipe 1 is heated and evaporated into a gaseous state, possessing a high heat transfer coefficient and fluidity. The steam passes through the adiabatic section 32 to the condensation section 31, where it exchanges heat with the heat-conducting fluid 41 outside the heat source heat pipe 1, is cooled and condensed into a liquid, and returns to the evaporation section 33 via the wall. Meanwhile, the temperature of the heat-conducting fluid 41 is above 70℃, and its fluid density is low, while the density of the cold source heat pipe 2 is high. The density is higher than the fluid density, so the cold source heat pipe 2 is positioned lower, compressing the heat transfer fluid 41. The heat transfer fluid 41 is compressed and raised within the nested component 42, covering the evaporation section 13 of the cold source heat pipe 2. The heat transfer fluid 41 has a large contact area with the condensation section 31 of the heat source heat pipe 1 and the cold source heat pipe 2, resulting in good heat exchange. Part of the liquid in the working fluid 21 is evaporated into gas, reaching the condensation section 11 of the cold source heat pipe 2. After being cooled and condensed by the cold fluid, it returns to the evaporation section 13 via the wall, forming a cycle. The relative positions of this nested heat pipe and the liquid level of the heat transfer fluid 41 are as follows: Figure 2 As shown.

[0043] When the flue gas temperature is below 90℃, the hot flue gas flows through the evaporation section 33 of the heat pipe at the bottom of the heat source heat pipe 1. The working fluid 30 inside the heat source heat pipe 1 circulates in the same way as at high temperatures, except that the internal evaporation flow rate is reduced. However, because the heat source temperature is low, the temperature of the heat transfer fluid 41 is below 70℃. The density of the heat transfer fluid 41 increases due to cooling and contraction. The density of the cold source heat pipe 2 is lower than the fluid density, so the cold source heat pipe 2 floats on the heat transfer fluid 41. Part of the heat transfer fluid 41 is below the cold source heat pipe 2, and the liquid level of the heat transfer fluid 41 drops rapidly, only covering a small part of the evaporation section 13 of the cold source heat pipe 2. The contact area between the heat transfer fluid 41 and the condensation section 31 of the heat source heat pipe 1 and the cold source heat pipe 2 is small, resulting in poor heat exchange. The circulation rate of the working fluid 21 in the cold source heat pipe 2 also decreases. The reduced heat exchange effect causes the heat exchange capacity of the heat source to automatically decrease significantly, and its temperature drop is thus greatly reduced or even close to zero. The relative positions of this part of the nested heat pipes and the liquid level of the heat transfer fluid are as follows. Figure 1 As shown.

[0044] Second Implementation Method

[0045] like Figure 3 and Figure 4The diagram illustrates a second embodiment of the present invention, wherein components identical or corresponding to those in the first embodiment are referenced using the same reference numerals as those in the first embodiment. For simplicity, only the differences between the second and first embodiments are described below. The difference between the second and first embodiments lies in that, in this embodiment, the lower heat source heat pipe 1 is nested within the upper cold source heat pipe 2. The process and effects resulting from temperature changes in this embodiment are the same as in the first embodiment. Considering that the density of the heat pipe typically differs significantly from the density of the heat-conducting fluid 41, a bottom ring 44 for adjusting the density material is used to reduce (using a lightweight material) or increase (using a heavyweight material) the density of the heat pipe, thereby matching its density with that of the heat-conducting fluid 41 at a specific temperature. Simultaneously, by covering the cold source heat pipe 2 with both inner and outer fluids, the heat exchange area between the heat-conducting fluid 41 and the cold source heat pipe 2 is increased.

[0046] The above embodiments are merely for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A temperature-limited nested heat pipe heat exchanger, characterized in that, include: A cold source heat pipe, wherein a working fluid is provided inside the cold source heat pipe; Heat source heat pipe, wherein the heat source heat pipe is provided with working fluid II; Nesting component, used for nesting and connecting the cold source heat pipe and the heat source heat pipe, and containing heat-conducting fluid inside; When the temperature of the heat-conducting fluid inside the nested component is different from that of the outside, the contact area between the heat-conducting fluid and the outer wall of the cold source heat pipe changes. The temperature-limited nested heat pipe heat exchange device further includes a heat exchange method, specifically comprising: when the ambient temperature is higher than the set temperature, the density of the heat-conducting fluid is lower than the density of the first working fluid in the cold source heat pipe, and the first working fluid in the cold source heat pipe compresses the heat-conducting fluid, thereby increasing the contact area between the heat-conducting fluid and the cold source heat pipe; when the ambient temperature is lower than the set temperature, the density of the heat-conducting fluid is higher than the density of the first working fluid in the cold source heat pipe, and the cold source heat pipe floats on the heat-conducting fluid, with some of the heat-conducting fluid flowing to the bottom of the cold source heat pipe, thereby reducing the contact area between the heat-conducting fluid and the cold source heat pipe; when the ambient temperature is equal to the set temperature, the temperature of the heat-conducting fluid, the heat pipe, and the ambient temperature are consistent, and they are in a temperature-limited equilibrium state.

2. The temperature-limited nested heat pipe heat exchanger according to claim 1, characterized in that: The cold source heat pipe is positioned above the heat source heat pipe.

3. The temperature-limited nested heat pipe heat exchanger according to claim 1, characterized in that: It also includes a positioning device for adjusting and keeping the center positions of the upper and lower heat pipes in a straight line.

4. The temperature-limited nested heat pipe heat exchanger according to claim 1, characterized in that: The nested component is a π-shaped nested component.

5. The temperature-limited nested heat pipe heat exchanger according to claim 1, characterized in that: The nesting component is disposed on the outer wall of the cold source heat pipe.

6. The temperature-limited nested heat pipe heat exchanger according to claim 1, characterized in that: There is a gap between the nested component and the bottom of the cold source heat pipe.

7. The temperature-limited nested heat pipe heat exchanger according to claim 1, characterized in that: The nesting component has a hole, the diameter of which is smaller at the top than at the bottom.

8. The temperature-limited nested heat pipe heat exchanger according to claim 1, characterized in that: The lower part of the cold source heat pipe is provided with an evaporation section one, and the upper part of the heat source heat pipe is provided with a condensation section two.

9. The temperature-limited nested heat pipe heat exchanger according to claim 8, characterized in that: The evaporation section one and the condensation section two overlap when the upper and lower heat pipes are nested, forming a heat exchanger.

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