A multi-stage refrigeration and heat exchange system
By using an alternating S-shaped pipeline structure for nitrogen in a multi-stage refrigeration and heat exchange system, the problems of unutilized cooling capacity and uneven temperature gradient after liquid nitrogen vaporization are solved, achieving efficient utilization of cold energy and stable supply of low-temperature environment, meeting the needs of high-power and high-precision refrigeration equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI TOFFLON SCI & TECH CO LTD
- Filing Date
- 2025-07-25
- Publication Date
- 2026-07-03
AI Technical Summary
In traditional liquid nitrogen refrigeration systems, the cooling capacity carried by the nitrogen gas after liquid nitrogen vaporization is not fully utilized, and the uneven temperature gradient distribution between nitrogen gas and the heat transfer medium during multi-stage series heat exchange leads to local heat exchange saturation, making it difficult to meet the needs of high-power and high-precision refrigeration equipment.
The system employs N sets of parallel liquid nitrogen-nitrogen heat exchangers and N+1 sets of nitrogen-heat transfer medium heat exchangers to form an alternating nitrogen S-shaped pipeline structure. The nitrogen gas after liquid nitrogen vaporization flows alternately with the heat transfer medium during the multi-stage heat exchange process. By increasing the temperature difference through countercurrent heat exchange, the system achieves the secondary utilization of nitrogen cooling capacity and the circulating cooling of the heat transfer medium.
It improves the utilization rate of cold energy, enhances the cooling effect, meets the requirements of high-power and high-precision refrigeration equipment for low-temperature environments, avoids local heat exchange saturation, and ensures the continuity and stability of refrigeration.
Smart Images
Figure CN224455027U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of cryogenic refrigeration, and in particular to a multi-stage refrigeration and heat exchange system. Background Technology
[0002] In existing technologies, liquid nitrogen, with its extremely low boiling point and excellent cooling performance, is widely used in many scenarios requiring deep cooling, such as superconducting equipment, aerospace simulation, and medical cryopreservation.
[0003] Currently, most traditional liquid nitrogen refrigeration systems employ single-stage heat exchange or simple multi-stage series heat exchange methods, achieving heat exchange through direct or indirect contact between liquid nitrogen and the medium to be refrigerated.
[0004] However, both of the above-mentioned heat exchange methods have certain drawbacks:
[0005] In traditional single-stage heat exchange systems, the nitrogen gas formed after liquid nitrogen vaporization often carries a large amount of cooling capacity that is not fully utilized before being directly discharged, resulting in low cooling energy utilization and limited refrigeration efficiency. While simple multi-stage series heat exchange structures extend the heat exchange process to some extent, the heat exchange path between nitrogen and the heat transfer medium is relatively simple. During the flow of nitrogen, uneven temperature gradient distribution can lead to local heat saturation, resulting in insufficient continuity of cooling capacity transfer between heat exchange units. This makes it difficult to fully utilize the synergistic effect of multi-stage heat exchange and fails to meet the requirements of high-power, high-precision refrigeration equipment for a continuously stable low-temperature environment.
[0006] Therefore, a multi-stage refrigeration and heat exchange system is needed to solve the above problems. Utility Model Content
[0007] The purpose of this invention is to provide a multi-stage refrigeration and heat exchange system that fully utilizes the cooling capacity of nitrogen after liquid nitrogen vaporization, improves the utilization rate of cold energy and enhances the refrigeration effect, thereby meeting the application requirements of high-power, high-precision refrigeration equipment in continuous low-temperature environments.
[0008] To solve the above-mentioned technical problems, this utility model provides a multi-stage refrigeration and heat exchange system, comprising:
[0009] The inlet pipeline is used to transport liquid nitrogen;
[0010] N sets of liquid nitrogen-nitrogen heat exchangers are connected in parallel. Each liquid nitrogen-nitrogen heat exchanger has a vaporization channel for liquid nitrogen vaporization that is independently connected to the input pipeline and a return channel for nitrogen flow.
[0011] N+1 nitrogen-thermal medium heat exchangers, wherein the nitrogen-thermal medium heat exchangers have heat exchange channels and thermal medium channels;
[0012] The inlet of the upstream heat exchange channel is connected to the outlet of multiple sets of vaporization channels;
[0013] The nitrogen-heat transfer medium heat exchangers in group N+1 and the liquid nitrogen-nitrogen heat exchangers in group N are connected by connecting pipes, so that an S-shaped pipe structure with alternating nitrogen flow is formed between the multiple heat exchange channels and the multiple return channels.
[0014] The outlet of the downstream heat exchange channel is connected to an output pipe;
[0015] A heat-conducting medium pipeline is connected to multiple sets of heat-conducting medium channels and the equipment to be cooled, forming a circulation loop.
[0016] Furthermore, the flow direction of nitrogen in the reflux channel is opposite to the flow direction of liquid nitrogen in the vaporization channel;
[0017] The flow direction of the heat-conducting medium in the heat-conducting medium channel is opposite to the flow direction of nitrogen in the heat exchange channel.
[0018] Furthermore, the outlets of the multiple sets of vaporization channels are connected to the inlet of the upstream heat exchange channel via a manifold.
[0019] Furthermore, the input pipeline has branch pipelines matching the number of liquid nitrogen-nitrogen heat exchangers to connect to the inlets of multiple sets of vaporization channels.
[0020] Furthermore, a temperature sensor and a control valve are installed on the output pipeline.
[0021] Furthermore, both the liquid nitrogen-nitrogen heat exchanger and the nitrogen-thermal medium heat exchanger are configured as plate heat exchangers.
[0022] Furthermore, N is a positive integer ≥ 1.
[0023] Furthermore, the heat-conducting medium in the heat-conducting medium pipeline is silicone oil.
[0024] Compared with the prior art, the present invention has at least the following beneficial effects:
[0025] By setting up N sets of parallel liquid nitrogen-nitrogen heat exchangers and N+1 sets of nitrogen-heat transfer medium heat exchangers, and connecting them with connecting pipes to form an S-shaped pipeline structure for alternating nitrogen flow, liquid nitrogen enters the vaporization channel through the input pipe and vaporizes. The resulting nitrogen gas then enters the heat exchange channel to exchange heat with the heat transfer medium in the heat transfer medium channel. Subsequently, the nitrogen gas returns to the return channel and re-enters the liquid nitrogen-nitrogen heat exchanger to exchange heat with fresh liquid nitrogen, thus realizing the secondary utilization of nitrogen cooling capacity. At the same time, the heat transfer medium pipeline, multiple sets of heat transfer medium channels, and the equipment to be refrigerated form a circulation loop, so that the cooled heat transfer medium continuously supplies cooling to the equipment to be refrigerated. In this way, through multi-stage alternating heat exchange, the utilization rate of cold energy is improved, the cooling effect is enhanced, and the requirements of high-power, high-precision refrigeration equipment for low-temperature environments are met. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the structure of a multi-stage refrigeration and heat exchange system in one embodiment of the present invention.
[0027] Reference numerals: 1. Input pipeline; 11. Branch pipeline; 2. Liquid nitrogen-nitrogen heat exchanger; 21. Vaporization channel; 22. Return channel; 3. Nitrogen-heat transfer medium heat exchanger; 31. Heat exchange channel; 32. Heat transfer medium channel; 4. Connecting pipeline; 5. Output pipeline; 51. Temperature sensor; 52. Control valve; 6. Heat transfer medium pipeline; 7. Manifold. Detailed Implementation
[0028] The multi-stage refrigeration and heat exchange system of this utility model will now be described in more detail with reference to the schematic diagrams, which illustrate preferred embodiments of this utility model. It should be understood that those skilled in the art can modify the utility model described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit this utility model.
[0029] Furthermore, based on the teachings of this specification, those skilled in the art can form new technical solutions through cross-combination of different implementation methods without creating technical contradictions. Such variations should all be considered to fall within the protection scope of this patent.
[0030] The present invention will be described in more detail below by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.
[0031] like Figure 1As shown in the figure, this utility model embodiment proposes a multi-stage refrigeration and heat exchange system, including an input pipeline 1 for transporting liquid nitrogen, providing a refrigerant source for the entire refrigeration system, and ensuring that the liquid nitrogen can stably and continuously enter the subsequent heat exchange stages.
[0032] N sets of liquid nitrogen-nitrogen heat exchangers 2 are arranged in parallel. Each liquid nitrogen-nitrogen heat exchanger 2 has a vaporization channel 21 for liquid nitrogen vaporization and is independently connected to the input pipeline 1, as well as a return channel 22 for nitrogen flow.
[0033] By setting up N sets of parallel liquid nitrogen-nitrogen heat exchangers 2, the paths for liquid nitrogen vaporization and nitrogen reflux heat exchange can be increased, thereby improving heat exchange efficiency. Furthermore, by making the vaporization channel 21 independently connected to the input pipeline 1, the liquid nitrogen vaporization process of each heat exchanger can be ensured to be free from mutual interference, making the liquid nitrogen vaporization more uniform. By setting up the reflux channel 22, a channel can be provided for nitrogen to participate in heat exchange again.
[0034] The N+1 group of nitrogen-thermal medium heat exchangers 3 includes a heat exchange channel 31 and a thermal medium channel 32. By setting up the N+1 group of nitrogen-thermal medium heat exchangers 3, they can better cooperate with the liquid nitrogen-nitrogen heat exchanger 2 for multi-stage heat exchange. Furthermore, the heat exchange channel 31 and the thermal medium channel 32 are respectively used for the flow of nitrogen and the flow of the thermal medium, allowing them to exchange heat within the liquid nitrogen-nitrogen heat exchanger 2.
[0035] The inlet of the upstream heat exchange channel 31 is connected to the outlet of the multiple sets of vaporization channels 21, and is used to receive nitrogen gas vaporized from liquid nitrogen.
[0036] The nitrogen-heat transfer medium heat exchangers 3 in group N+1 and the liquid nitrogen-nitrogen heat exchangers 2 in group N are connected by a connecting pipe 4, forming an S-shaped pipeline structure with alternating nitrogen flow between the multiple heat exchange channels 31 and the multiple return channels 22. This S-shaped pipeline structure extends the flow path of nitrogen, allowing it to fully contact different heat exchange units (such as liquid nitrogen in the vaporization channel 21 and the heat transfer medium in the heat transfer medium channel 32) as it alternately flows through the heat exchange channels 31 and the return channels 22. This multi-stage heat exchange avoids local heat saturation, enhances the heat exchange effect between nitrogen and each heat exchange unit, makes the cold energy transfer more continuous, and fully utilizes the synergistic effect of multi-stage heat exchange.
[0037] The outlet of the downstream heat exchange channel 31 is connected to an output pipe 5 for the discharge of nitrogen.
[0038] The heat transfer medium pipeline 6 is connected to multiple sets of heat transfer medium flow channels 32 and the equipment to be cooled (as indicated by the dotted box in the figure), forming a circulation loop. This allows the cooled heat transfer medium to circulate through the equipment to be cooled, continuously providing cooling capacity to the equipment, while simultaneously carrying the heat generated by the equipment back to the heat exchanger for cooling, achieving a continuous supply of cooling capacity, ensuring that the equipment to be cooled is in a stable low-temperature environment, and improving the continuity and stability of cooling.
[0039] It should be noted that the heat-conducting medium in the heat-conducting medium pipeline 6 is silicone oil.
[0040] This system is equipped with N sets of parallel liquid nitrogen-nitrogen heat exchangers 2 and N+1 sets of nitrogen-heat transfer medium heat exchangers 3. The two are connected by connecting pipes 4 to form an S-shaped pipeline structure with alternating nitrogen flow. Liquid nitrogen enters the vaporization channel 21 through the input pipe 1 and vaporizes. The resulting nitrogen gas enters the heat exchange channel 31 and exchanges heat with the heat transfer medium in the heat transfer medium channel 32. Then, the nitrogen gas returns to the return channel 22 and re-enters the liquid nitrogen-nitrogen heat exchanger 2 to exchange heat with fresh liquid nitrogen, realizing the secondary utilization of nitrogen cooling capacity. At the same time, the heat transfer medium pipeline 6 forms a circulation loop with multiple sets of heat transfer medium channels 32 and the equipment to be refrigerated, so that the cooled heat transfer medium continuously supplies cooling to the equipment to be refrigerated. In this way, through multi-stage alternating heat exchange, the utilization rate of cold energy is improved, the cooling effect is enhanced, and the requirements of high-power and high-precision refrigeration equipment for low-temperature environments are met.
[0041] Furthermore, by setting up a nitrogen-heat transfer medium heat exchanger 3, the direct contact between the silicone oil and the heat exchanger where liquid nitrogen phase change occurs can be avoided, thus preventing the silicone oil from undergoing drastic temperature changes. This makes the cooling process of the silicone oil more stable and controllable, avoiding the risk of silicone oil freezing.
[0042] In this embodiment, N is a positive integer ≥1 to increase the number of heat exchange stages between nitrogen and liquid nitrogen, and between nitrogen and the heat transfer medium, thereby improving the heat exchange and cooling effect.
[0043] Preferably, if there are two liquid nitrogen-nitrogen heat exchangers 2, then there are three nitrogen-heat transfer medium heat exchangers 3.
[0044] In a further embodiment, the flow direction of liquid nitrogen in the return channel 22, the flow direction of nitrogen in the vaporization channel 21, the flow direction of the heat transfer medium in the heat transfer medium channel 32, and the flow direction of nitrogen in the heat exchange channel 31 are further defined to improve the heat exchange effect.
[0045] Specifically, the flow direction of nitrogen gas in the return channel 22 is opposite to the flow direction of liquid nitrogen in the vaporization channel 21. Utilizing the principle of countercurrent heat exchange, the temperature gradient between nitrogen gas and liquid nitrogen can be increased, ensuring a large temperature difference between them throughout the heat exchange process. This enhances the heat exchange intensity between nitrogen gas and liquid nitrogen, allowing nitrogen gas to more fully absorb the cooling energy from liquid nitrogen, while liquid nitrogen can more efficiently complete the vaporization process, further improving the efficiency of cooling energy recovery and utilization.
[0046] Correspondingly, the flow direction of the heat transfer medium in the heat transfer medium flow channel 32 is opposite to the flow direction of nitrogen in the heat exchange flow channel 31. By utilizing the same counter-current heat exchange characteristic, the average temperature difference between the heat transfer medium and nitrogen is increased, extending the effective heat exchange time between the two. This allows the heat transfer medium to fully absorb the cooling capacity carried by the nitrogen, lowering its own temperature. Consequently, when circulating through the equipment to be cooled, it can more effectively cool the equipment, enhancing the overall cooling effect and ensuring a more stable and sufficient supply of cooling capacity to the equipment.
[0047] The outlets of the multiple vaporization channels 21 are connected to the inlet of the upstream heat exchange channel 31 through the manifold 7 to avoid turbulence when multiple streams of nitrogen enter directly, to ensure the stability of nitrogen entering the heat exchange channel 31, to make the distribution of nitrogen in the heat exchange channel 31 more uniform, and to improve the initial heat exchange efficiency with the heat transfer medium.
[0048] Furthermore, the input pipeline 1 has branch pipelines 11 that match the number of liquid nitrogen-nitrogen heat exchangers 2, so as to communicate with the inlets of multiple sets of vaporization channels 21.
[0049] Preferably, the output pipeline 5 is equipped with a temperature sensor 51 and a control valve 52. The temperature sensor 51 can monitor the temperature of the nitrogen discharged after multiple heat exchanges in real time, thereby reflecting the heat exchange effect and cooling capacity utilization of the system. The control valve 52 can adjust the nitrogen discharge rate based on the monitoring data of the temperature sensor 51, and promptly adjust the nitrogen flow rate in the system when the temperature is abnormal, ensuring that the system is always in the optimal heat exchange state, thereby improving the intelligent control level and operational reliability of the system.
[0050] In this embodiment, both the liquid nitrogen-nitrogen heat exchanger 2 and the nitrogen-heat transfer medium heat exchanger 3 are plate heat exchangers. Because plate heat exchangers have a larger heat exchange area and higher heat exchange efficiency, they can enhance the heat transfer rate between nitrogen and liquid nitrogen, and between nitrogen and the heat transfer medium, thus shortening the heat exchange time. At the same time, the structure of plate heat exchangers is more compact, facilitating the arrangement and connection of multiple heat exchangers, better adapting to the space requirements of S-shaped pipe structures, and improving the overall heat exchange performance and integration of the system.
[0051] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.
Claims
1. A multi-stage refrigeration heat exchange system, characterized by, include: The inlet pipe (1) is used to transport liquid nitrogen; N sets of parallel liquid nitrogen-nitrogen heat exchangers (2), each liquid nitrogen-nitrogen heat exchanger (2) having a vaporization channel (21) for liquid nitrogen vaporization and independently connected to the input pipeline (1) and a return channel (22) for nitrogen flow. N+1 group nitrogen-thermal medium heat exchanger (3), the nitrogen-thermal medium heat exchanger (3) has a heat exchange channel (31) and a thermal medium channel (32); The inlet of the upstream heat exchange channel (31) is connected to the outlet of the multiple sets of vaporization channels (21); The nitrogen-heat transfer medium heat exchanger (3) of group N+1 and the liquid nitrogen-nitrogen heat exchanger (2) of group N are connected by a connecting pipe (4), so that an S-shaped pipeline structure with alternating nitrogen flow is formed between the multiple heat exchange channels (31) and the multiple return channels (22). The outlet of the downstream heat exchange channel (31) is connected to an output pipe (5); The heat-conducting medium pipeline (6) is connected to multiple sets of heat-conducting medium channels (32) and the equipment to be cooled, forming a circulation loop.
2. The multi-stage refrigeration heat exchange system of claim 1, wherein, The flow direction of nitrogen in the reflux channel (22) is opposite to the flow direction of liquid nitrogen in the vaporization channel (21); The flow direction of the heat-conducting medium in the heat-conducting medium channel (32) is opposite to the flow direction of nitrogen in the heat exchange channel (31).
3. The multi-stage refrigeration heat exchange system of claim 1, wherein, The outlets of the multiple sets of vaporization channels (21) are connected to the inlet of the upstream heat exchange channel (31) through the manifold (7).
4. The multi-stage refrigeration heat exchange system of claim 1, wherein, The input line (1) has branch lines (11) matching the number of liquid nitrogen-nitrogen heat exchangers (2) to communicate with the inlets of multiple sets of vaporization channels (21).
5. The multi-stage refrigeration heat exchange system of claim 1, wherein, A temperature sensor (51) and a control valve (52) are installed on the output pipeline (5).
6. The multi-stage refrigeration heat exchange system of claim 1, wherein, Both the liquid nitrogen-nitrogen heat exchanger (2) and the nitrogen-thermal medium heat exchanger (3) are plate heat exchangers.
7. The multi-stage refrigeration heat exchange system of claim 1, wherein, N is a positive integer ≥ 1.
8. The multi-stage refrigeration heat exchange system of claim 1, wherein, The heat-conducting medium in the heat-conducting medium pipeline (6) is silicone oil.