Heat exchanger maximum allowable temperature difference test method and test device

Abstract

The present invention relates to the field of heat exchangers, and provides a method and device for testing the maximum allowable temperature difference of a heat exchanger, wherein the method for testing the maximum allowable temperature difference of a heat exchanger comprises: controlling the temperature change of each temperature detection point in the heat exchanger to be less than a first temperature change rate, so that the flow rate of the first medium and the second medium reaches a standard flow rate value; adjusting the flow rate of the first medium and / or the second medium to increase the temperature difference in the heat exchanger until the heat exchanger becomes abnormal. In order to solve the defect that the maximum temperature difference of the heat exchanger under special working conditions cannot be obtained in the prior art, the method for testing the maximum allowable temperature difference of the heat exchanger provided by the present invention stabilizes the flow rate of the first medium and the second medium passing through the heat exchanger at a standard flow rate value, and then increases the temperature difference in the heat exchanger by adjusting the flow rate of the first medium and / or the second medium, thereby obtaining the maximum allowable temperature difference value of the heat exchanger, which has a high reference value for the rapid startup and safe operation of the liquid air energy storage system.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchanger performance testing, and in particular to a method and a device for testing a maximum allowable temperature difference of a heat exchanger. Background Art

[0002] Aluminum plate-fin heat exchangers have been widely used in the fields of air separation and natural gas liquefaction due to their high heat transfer efficiency, compact structure, small size, and low temperature resistance. In recent years, with the development of liquid air energy storage technology, aluminum plate-fin heat exchangers have also been widely used as main heat exchangers in the process of air cooling and liquefaction. During the operation of the plate-fin heat exchanger, there is a temperature difference between adjacent channels, and the thermal stress caused by the temperature difference is constrained to a relatively small local range due to the structure of the heat exchanger. When the temperature difference is too large, the internal thermal stress exceeds the allowable use range of the material used or exceeds the tensile strength of the brazing layer of the fins and the partitions, which will cause damage to the heat exchanger.

[0003] In order to avoid damage to the heat exchanger caused by internal thermal stress caused by temperature difference, NB / T47006-2019 "Aluminum Plate-Fin Heat Exchanger" has relevant provisions on the maximum allowable temperature difference between heat exchanger channels, that is, under stable conditions, the maximum allowable temperature difference between heat exchanger channels (same cross-section) is about 50°C; in the presence of phase change fluid and instantaneous circulation, the maximum allowable temperature difference should not exceed 30°C.

[0004] However, in some application scenarios, such as the plate-fin heat exchanger of the liquid air energy storage project, the plate-fin heat exchanger operates intermittently with the alternation of the energy storage process and the energy release process. There is a parking stage between the energy storage process and the energy release process. During the parking stage, the axial temperature gradient of the heat exchanger changes due to heat conduction inside the heat exchanger. When it is restarted, it is necessary to introduce the medium at a certain rate according to the internal temperature of the heat exchanger to re-establish the temperature gradient. In order to achieve a rapid response, the shorter the time to re-establish the temperature gradient of the heat exchanger, the better. In this process, it is inevitable that the temperature difference between the heat exchanger channels (the same cross-section) will be large, causing damage to the heat exchanger. Therefore, under some special working conditions, it is very important to understand the maximum allowable temperature difference of the heat exchanger to ensure the normal use of the heat exchanger. Summary of the invention

[0005] The present invention provides a method and a device for testing the maximum allowable temperature difference of a heat exchanger, which are used to solve the defect that the maximum allowable temperature difference of a heat exchanger cannot be accurately obtained in the prior art, and to change the flow rate of the first medium and / or the second medium to increase the temperature difference to test the heat exchanger under test until the heat exchanger under test becomes abnormal, thereby detecting the maximum allowable temperature difference value of the heat exchanger under test.

[0006] The present invention provides a method for testing the maximum allowable temperature difference of a heat exchanger, comprising:

[0007] Passing a first medium and a second medium having a temperature difference into the heat exchanger;

[0008] Controlling the temperature change of each temperature detection point in the heat exchanger to be less than a first temperature change rate, so that the flow rate of the first medium and the second medium reaches a standard flow rate value;

[0009] The flow rate of the first medium and / or the second medium is adjusted to increase the temperature difference in the heat exchanger until the heat exchanger becomes abnormal, and the temperature difference value obtained is the maximum allowable temperature difference value of the heat exchanger.

[0010] According to the maximum allowable temperature difference testing method for a heat exchanger provided by the present invention, controlling the temperature change of each temperature detection point in the heat exchanger to be less than a first temperature change rate includes: controlling the temperature change of the temperature detection points of the channel where the first medium and the second medium are located on the same cross-section in the heat exchanger to be less than the first temperature change rate.

[0011] According to the maximum allowable temperature difference test method for a heat exchanger provided by the present invention, the heat exchanger includes at least two temperature test cross sections, and the temperature differences of the channels where the first medium and the second medium are located on each cross section in the heat exchanger are controlled to be within the same range.

[0012] According to the maximum allowable temperature difference test method for a heat exchanger provided by the present invention, increasing the temperature difference in the heat exchanger includes: increasing the temperature difference in the same cross section in the heat exchanger according to a set temperature gradient, and stably operating at each temperature difference gradient value for a set time period.

[0013] According to the maximum allowable temperature difference testing method for a heat exchanger provided by the present invention, the first medium is air and the second medium is water.

[0014] According to the maximum allowable temperature difference testing method for a heat exchanger provided by the present invention, the first medium and the second medium are liquid nitrogen and nitrogen gas.

[0015] The present invention also provides a heat exchanger maximum allowable temperature difference test device, comprising:

[0016] A heat exchanger to be tested, wherein a plurality of temperature detection points are arranged along a medium flow direction of the heat exchanger to be tested;

[0017] a first heat exchange circuit, wherein the first heat exchange circuit is connected to a first heat exchange side of the tested heat exchanger, a first medium is introduced into the tested heat exchanger, and an output flow rate of the first medium is controlled;

[0018] a second heat exchange circuit, wherein the second heat exchange circuit is connected to a second heat exchange side of the tested heat exchanger, a second medium is introduced into the tested heat exchanger, and an output flow rate of the first medium is controlled;

[0019] There is a temperature difference between the first medium and the second medium.

[0020] According to the heat exchanger maximum allowable temperature difference testing device provided by the present invention, the tested heat exchanger includes a first temperature sensor group and a second temperature sensor group, the first temperature sensor group and the second temperature sensor group are arranged on the same cross-section, the first temperature sensor group is used to detect the first heat exchange side of the tested heat exchanger, and the second temperature sensor group is used to detect the second heat exchange side of the tested heat exchanger.

[0021] According to the heat exchanger maximum allowable temperature difference testing device provided by the present invention, the first temperature sensor group on the same cross-section includes at least two first temperature sensors, and the first temperature sensors are used to measure the temperature of the channel on the first heat exchange side; the second temperature sensor group on the same cross-section includes at least two second temperature sensors, and the second temperature sensors are used to measure the temperature of the channel on the second heat exchange side.

[0022] The device for testing the maximum allowable temperature difference of a heat exchanger provided by the present invention further includes a controller, which is electrically connected to the first temperature sensor group, the second temperature sensor group, and the valves of the first heat exchange circuit and the second heat exchange circuit.

[0023] The maximum allowable temperature difference test method for a heat exchanger provided by the present invention stabilizes the flow rates of the first medium and the second medium passing through the heat exchanger at a standard flow rate value, and then increases the temperature difference in the heat exchanger by adjusting the flow rates of the first medium and / or the second medium, thereby obtaining the maximum allowable temperature difference value of the heat exchanger. The maximum temperature difference value has a high reference value for the rapid startup and safe operation of the liquid air energy storage system.

[0024] Furthermore, in the heat exchanger maximum allowable temperature difference testing device provided by the present invention, since it can implement the heat exchanger maximum allowable temperature difference testing method, it also has the various advantages as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 This is one of the flow diagrams of the maximum allowable temperature difference test method for a heat exchanger provided by the present invention;

[0027] Figure 2This is the second flow chart of the maximum allowable temperature difference test method for a heat exchanger provided by the present invention;

[0028] Figure 3 This is one of the system connection diagrams of the heat exchanger maximum allowable temperature difference test device provided by the present invention;

[0029] Figure 4 This is the second system connection diagram of the heat exchanger maximum allowable temperature difference test device provided by the present invention;

[0030] Figure 5 is a schematic diagram of a heat exchanger to be tested provided by the present invention;

[0031] Figure 6 It is one of the schematic diagrams of the internal channel of the tested heat exchanger provided by the present invention;

[0032] Figure 7 This is the second schematic diagram of the internal channel of the tested heat exchanger provided by the present invention;

[0033] Figure 8 It is a schematic diagram of installing the temperature sensor of the tested heat exchanger provided by the present invention.

[0034] Reference numerals:

[0035] 100: first heat exchange circuit; 101: compressor; 102: air filter; 103: first flow meter; 104: first flow regulating valve; 105: first pressure regulating valve; 110: first liquid nitrogen pump; 120: first vaporizer; 130: second heater; 140: first switch valve;

[0036] 200: second heat exchange circuit; 201: water pump; 202: first water storage tank; 203: first heater; 204: second water storage tank; 205: second flow meter; 206: second flow regulating valve; 210: second liquid nitrogen pump; 220: second vaporizer; 230: third heater; 240: second switch valve;

[0037] 300: tested heat exchanger; 301: first temperature sensor group; 302: second temperature sensor group; 310: first inlet; 311: first outlet; 320: second inlet; 321: second outlet; 330: core; 331: first channel; 332: second channel;

[0038] 400: controller; 500: first liquid nitrogen storage tank; 510: second liquid nitrogen storage tank; 501: third flow regulating valve; 502: third flow meter; 503: fourth flow regulating valve; 504: fourth flow meter. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the description of the embodiments of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0041] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0042] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0043] Combine the following Figures 1 to 8 It should be understood that the following description is only an illustrative embodiment of the present invention and does not constitute a limitation on the present invention.

[0044] like Figure 1 As shown, the present invention provides a method for testing the maximum allowable temperature difference of a heat exchanger, comprising:

[0045] S1: introducing a first medium and a second medium having a temperature difference into a heat exchanger;

[0046] S2: Control the temperature change rate of each temperature detection point of the heat exchanger to be less than the first temperature change rate, so that the flow rate of the first medium and the second medium reaches the standard flow rate value;

[0047] S3: adjusting the flow rate of the first medium and / or the second medium to increase the temperature difference in the heat exchanger until the heat exchanger becomes abnormal, and obtaining the temperature difference value as the maximum allowable temperature difference value of the heat exchanger.

[0048] Specifically, there are a first heat exchange side and a second heat exchange side in the heat exchanger, a first medium is passed into the first heat exchange side, and a second medium is passed into the second heat exchange side, and a temperature difference is formed between the first heat exchange side and the second heat exchange side through the first medium and the second medium in the heat exchanger. In the initial state, the temperature difference between the first medium and the second medium can be a calibrated temperature difference value of the heat exchanger.

[0049] When the first medium and the second medium are introduced into the heat exchanger, the initial flow rate is small, so that the temperature difference is gradually established in the heat exchanger, and then the flow rate is continuously increased until the flow rates of the first medium and the second medium reach the standard flow rate. In the process of increasing the flow rate, the temperature change rate of each temperature detection point of the heat exchanger should always be kept less than the first temperature change rate. Among them, the temperature detection points are arranged at intervals along the flow direction of the heat exchange medium.

[0050] In addition, the standard flow rate values ​​of the inlet flow rates of the first medium and the second medium of the heat exchanger can be obtained by simulating and calculating the heat exchanger to be tested on the EDR according to the heat exchange area and channel arrangement of the heat exchanger to be tested and the set test temperature before the test.

[0051] After the inflow flow of the first medium and the second medium stabilizes at the standard flow value, the temperature difference in the heat exchanger begins to increase. The increase in temperature difference is achieved by adjusting the inflow of the first medium and the second medium. For example, when the inflow of the first medium with a lower temperature remains unchanged, the inflow of the second medium with a higher temperature is increased. When the inflow of the second medium with a higher temperature remains unchanged, the inflow of the first medium with a lower temperature is reduced. By controlling the flow of the first medium and the second medium to increase the temperature difference, the rapid start-up condition of the liquid air energy storage system is simulated.

[0052] Among them, the heat exchanger abnormality includes damage, deformation and / or abnormal sound of the heat exchanger. After obtaining the maximum allowable temperature difference of the heat exchanger under this working condition, the flow rate of the heat exchanger medium can be controlled during the rapid start of the liquid air energy storage, thereby obtaining the maximum rapid start time.

[0053] In addition, in one embodiment of the present invention, the step of controlling the temperature change rate of each temperature detection point in the heat exchanger to be less than the first temperature change rate in step S2 includes: controlling the temperature change rate of the temperature detection point of the channel where the first medium and the second medium are located on the same cross section in the heat exchanger to be less than the first temperature change rate. The first temperature change rate is set according to conventional operating experience, for example, the first temperature change rate of the plate-fin heat exchanger can be 30°C / h, and the first temperature change rate of the coiled heat exchanger can be 50°C / h.

[0054] Furthermore, in some embodiments of the present invention, the heat exchanger includes at least two temperature test cross sections, and the temperature differences of the channels where the first medium and the second medium are located on each cross section in the heat exchanger are controlled to be within the same range.

[0055] Specifically, in step S2, after the inlet flow rates of the first medium and the second medium reach the standard flow rate value, they are maintained for a certain period of time, and the temperature difference of each cross section of the heat exchanger is observed, and the flow rates of the first medium and the second medium are adjusted within a certain range to maintain the temperature difference of each cross section of the heat exchanger within a certain and smaller range.

[0056] In addition, in an optional embodiment of the present invention, the step of increasing the temperature difference in the heat exchanger in step S3 includes: increasing the temperature difference in the same cross section of the heat exchanger according to a set temperature gradient, and stably operating at each temperature difference gradient value for a set time period.

[0057] For example, Figure 2 As shown, the steps of increasing the temperature difference include:

[0058] S31: adjusting the flow rate of the first medium and / or the second medium so that the temperature difference of the same cross section in the heat exchanger is a first temperature value; wherein the first temperature value is greater than the temperature difference between the first medium and the second medium in step S2;

[0059] S32: maintaining the current flow rates of the first medium and the second medium for a first time period;

[0060] S33: When the heat exchanger is normal, further adjusting the flow rate of the first medium and / or the second medium so that the temperature difference value of the same cross section in the heat exchanger is a second temperature value, wherein the second temperature value is greater than the first temperature value;

[0061] S34: maintaining the current flow rates of the first medium and the second medium for a second time period;

[0062] S35: Execute steps S33 and S34 in a loop until the heat exchanger becomes abnormal.

[0063] The first time period and the second time period may be the same or different. When steps S33 and S34 are continuously executed in a cycle, the temperature difference in the heat exchanger is continuously increased, that is, the second temperature difference value increases once in each cycle. The increase range may be the same or different.

[0064] In an optional embodiment of the present invention, when the heat exchanger is in a normal temperature or high temperature environment, the first medium may be air and the second medium may be water.

[0065] Furthermore, in another embodiment of the present invention, when the heat exchanger is in a cryogenic environment, the first medium and the second medium may be nitrogen.

[0066] like Figure 3 and Figure 4 As shown, the present invention also provides a heat exchanger maximum allowable temperature difference test device, including: a tested heat exchanger 300, a first heat exchange loop 100 and a second heat exchange loop 200, wherein the tested heat exchanger 300 is provided with a plurality of temperature detection points along the medium flow direction; the first heat exchange loop 100 is connected to the first heat exchange side of the tested heat exchanger 300, a first medium is introduced into the tested heat exchanger 300, and the output flow rate of the first medium is controlled; the second heat exchange loop 200 is connected to the second heat exchange side of the tested heat exchanger 300, a second medium is introduced into the tested heat exchanger 300, and the output flow rate of the first medium is controlled; wherein the first medium and the second medium have a temperature difference. A heat exchanger maximum allowable temperature difference test device of the present invention can be used to implement the heat exchanger maximum allowable temperature difference test method of the above-mentioned embodiment.

[0067] That is, the tested heat exchanger 300 includes a first inlet 310, a first outlet 311, a second inlet 320, and a second outlet 321. The first inlet 310 and the first outlet 311 are the inlet and outlet of the first heat exchange side, and the second inlet 320 and the second outlet 321 are the inlet and outlet of the second heat exchange side. The first heat exchange circuit 100 is connected to the first inlet 310 and the first outlet 311, and the second heat exchange circuit 200 is connected to the second inlet 320 and the second outlet 321.

[0068] like Figure 1 As shown, the first medium introduced into the first heat exchange loop 100 is room temperature air, and the second medium introduced into the second heat exchange loop 200 is high temperature hot water. Figure 2As shown, the first medium introduced into the first heat exchange loop 100 is low-temperature nitrogen, and the second medium introduced into the second heat exchange loop 200 is high-temperature nitrogen. The tested heat exchanger 300 may be a plate-fin heat exchanger, and temperature detection points are set equidistantly along the height direction of the tested heat exchanger 300, for example, at intervals of 500 mm. The temperature detection points detect the temperature in the first heat exchange side channel and the temperature in the second heat exchange side channel of each cross section of the tested heat exchanger 300, and then obtain the temperature difference value of the channels on both sides of each cross section.

[0069] like Figure 5 As shown, in some embodiments of the present invention, the tested heat exchanger 300 includes a first temperature sensor group 301 and a second temperature sensor group 302, and the first temperature sensor group 301 and the second temperature sensor group 302 are arranged on the same cross-section, the first temperature sensor group 301 is used to detect the temperature in the first heat exchange side channel of the tested heat exchanger 300, and the second temperature sensor group 302 is used to detect the temperature in the second heat exchange side channel of the tested heat exchanger 300.

[0070] like Figures 6 to 8 As shown, the first temperature sensor group 301 includes at least two first temperature sensors, and the first temperature sensors are used to measure the temperatures of the first channels 331 of multiple first heat exchange sides on the same cross section.

[0071] In other words, the second temperature sensor group 302 includes at least two second temperature sensors, and the second temperature sensors are used to measure the temperature of the second channels 332 on multiple second heat exchange sides on the same cross section. Among them, the first channels 331 and the second channels 332 are arranged alternately for heat exchange. The first temperature sensor and the second temperature sensor are provided with a protective sleeve, which is threadedly connected to the temperature sensor and inserted into the hole reserved on the seal 330 of the core. The protective sleeve prevents damage to the probe, and the protective sleeve and the seal of the tested heat exchanger 300 are connected by welding, so there is no need to worry about leakage. Among them, the first temperature sensor and the second temperature sensor can use platinum thermal resistors with aviation plug connectors. Among them, the number of first channels 331 and second channels 332 on both sides of the tested heat exchanger 300 is not less than 2 layers.

[0072] Specifically, Figure 1As shown, in one embodiment of the present invention, under the working condition that the first medium is air and the second medium is water, the test pressure and test temperature are set, wherein the air inlet temperature is the measured temperature, and the hot water inlet temperature can be 90°C. The test pressure is determined according to the design pressure of the tested heat exchanger. The first heat exchange loop 100 includes a compressor 101, a first flow regulating valve 104, a first flow meter 103, an air filter 102 and a first pressure regulating valve 105. The compressor 101 is connected to the air filter 102. The first flow meter 103 and the first flow regulating valve 104 are arranged on the pipeline between the compressor 101 and the air filter 102. The air filter 102 is connected to the first inlet 310. The air filter 102 filters the air compressed by the compressor 101. The first flow meter 103 obtains the incoming flow of the air and feeds it back to the first flow regulating valve 104. The flow detected by the first flow meter 103 is used to control the first flow regulating valve 104. The first pressure regulating valve 105 is arranged on the pipeline of the first outlet 311 to ensure that the pressure in the channel of the tested heat exchanger is constant.

[0073] The second heat exchange loop 200 includes a water pump 201, a first water storage tank 202, a second flow regulating valve 206 and a second flow meter 205. The first storage tank is connected to the water pump 201, the water pump 201 is connected to the second inlet 320, and the second flow meter 205 and the second flow regulating valve 206 are arranged on the pipeline of the second outlet 321. The second flow regulating valve 206 can be connected to the first water storage tank 202. Of course, the second heat exchange loop 200 can also include a second water storage tank 204, and the second flow regulating valve 206 is connected to the second water storage tank 204. Among them, the first heater 203 is arranged on the first water storage tank 202 or on the pipeline between the first water storage tank 202 and the water pump 201.

[0074] The water pump 201 pumps hot water from the first water tank 202 into the second inlet 320 of the tested heat exchanger 300, flows out from the second outlet 321, and flows back to the first water tank 202 or the second water tank 204. The second flow regulating valve 206 controls the outflow speed of the hot water, which is equivalent to controlling the flow rate of the hot water entering the second inlet 320. The second flow meter 205 obtains the flow rate of the second outlet 321 and feeds it back to the second flow regulating valve 206 for flow control.

[0075] In other embodiments of the present invention, the heat exchanger maximum allowable temperature difference test device further includes a controller 400, and the controller 400 is electrically connected to the first temperature sensor group 301, the second temperature sensor group 302, and the valves of the first heat exchange loop 100 and the second heat exchange loop 200. In other words, the controller is electrically connected to the first flow regulating valve 104, the first flow meter 103, the second flow regulating valve 206, the second flow meter 205, and the first pressure regulating valve 105. The controller 400 obtains flow values ​​from the first flow meter 103 and the second flow meter 205, and adjusts the first flow regulating valve 104 and the second flow regulating valve 206 based on the flow values.

[0076] Furthermore, if Figure 2 As shown, in another embodiment of the present invention, the first medium and the second medium are nitrogen. The test pressure and the test temperature are set, wherein the nitrogen inlet temperature (first inlet temperature) can be 30°C, and the low-temperature nitrogen inlet temperature (second inlet temperature) can be -120°C. The test pressure is in accordance with the design pressure of the heat exchanger being tested. The first heat exchange circuit 100 includes a first liquid nitrogen pump 110, a first vaporizer 120, and a second heater 130. The first liquid nitrogen pump 110 can pump liquid nitrogen from the first liquid nitrogen storage tank 500 into the first vaporizer 120 for gasification, and heat it in the second heater 130. The second heater 130 is connected to the first inlet 310. In addition, the first heat exchange circuit 100 also includes a first switch valve 140, and the first switch valve 140 is connected in parallel with the first vaporizer 120 and the second heater 130. A vent valve is provided on the pipeline between the second heater 130 and the first inlet 310. When the temperature of the nitrogen of the first medium entering the heat exchanger does not reach a preset value, the vent valve is opened to discharge the nitrogen until the temperature reaches the preset value.

[0077] In addition, the first heat exchange loop 100 further includes a fourth flow regulating valve 503, a fourth flow meter 504 and a second liquid nitrogen storage tank 510, the second liquid nitrogen storage tank 510 is connected to the second outlet 321, and the fourth flow regulating valve 503 and the fourth flow meter 504 are arranged on the pipeline between the second liquid nitrogen storage tank 510 and the second outlet 321. Among them, the fourth flow regulating valve 503 and the fourth flow meter 504 are connected to the controller 400, the controller 400 obtains the flow of the fourth flow meter 504, and controls the fourth flow regulating valve 503 based on the flow, and the fourth flow regulating valve 503 controls the flow of the first medium entering the first inlet 310.

[0078] The second heat exchange circuit 200 includes a second liquid nitrogen pump 210, a second vaporizer 220 and a third heater 230. The second liquid nitrogen pump 210 pumps liquid nitrogen from the first liquid nitrogen storage tank 500 to the second vaporizer 220 for vaporization, and then heats it through the third heater 230 to enter the second inlet 320. The nitrogen temperature after heating by the third heater 230 is lower than the nitrogen temperature after heating by the second heater 130, that is, the first medium temperature is higher than the second medium temperature. In addition, the second heat exchange circuit 200 also includes a second switch valve 240, and the second switch valve 240 is connected in parallel with the second vaporizer 220 and the third heater 230. A vent valve is also provided between the third heater 230 and the second inlet 320. In addition, the second heat exchange circuit 200 also includes a third flow meter 502 and a third flow regulating valve 501, and the second outlet 321 is connected to the second liquid storage tank, and the third flow meter 502 and the third flow regulating valve 501 are arranged between the second outlet 321 and the second liquid nitrogen storage tank 510. The third flow regulating valve 501 and the third flow meter 502 are connected to the controller 400. The controller 400 obtains the flow of the third flow meter 502 and controls the third flow regulating valve 501 based on the flow. The fourth flow regulating valve 503 controls the flow of the second medium entering the second inlet 320. The first liquid nitrogen storage tank 500 and the second liquid nitrogen storage tank 510 can be the same.

[0079] Further, temperature sensors may be provided at the first inlet 310, the second inlet 320, the first outlet 311 and the second outlet 321, and the temperature sensors are connected to the controller 400. The first liquid nitrogen pump 110 and the second liquid nitrogen pump 210 are frequency-controlled to adjust the pump outlet pressure, and the type of pump is not limited and is selected according to the adjustment range of the test pressure.

[0080] The maximum allowable temperature difference test method for a heat exchanger provided by the present invention stabilizes the flow rates of the first medium and the second medium passing through the heat exchanger at a standard flow rate value, and then increases the temperature difference in the heat exchanger by adjusting the flow rates of the first medium and / or the second medium, thereby obtaining the maximum allowable temperature difference value of the heat exchanger. The maximum temperature difference value has a high reference value for the rapid startup and safe operation of the liquid air energy storage system.

[0081] Furthermore, in the heat exchanger maximum allowable temperature difference testing device provided by the present invention, since it can implement the heat exchanger maximum allowable temperature difference testing method, it also has the various advantages as described above.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing the maximum allowable temperature difference of a heat exchanger, characterized in that: include: Passing a first medium and a second medium having a temperature difference into the heat exchanger; Controlling the temperature change rate of each temperature detection point in the heat exchanger to be less than the first temperature change rate, so that the flow rate of the first medium and the second medium reaches the standard flow rate value; Adjust the flow rate of the first medium and / or the second medium to increase the temperature difference in the heat exchanger until the heat exchanger becomes abnormal, and obtain the temperature difference value as the maximum allowable temperature difference value of the heat exchanger; The controlling the temperature change of each temperature detection point in the heat exchanger to be less than a first temperature change rate comprises: controlling the temperature change of the temperature detection points of the channel where the first medium and the second medium are located on the same cross section in the heat exchanger to be less than the first temperature change rate; The heat exchanger comprises at least two temperature test cross sections, and the temperature differences of the channels where the first medium and the second medium are located on each cross section in the heat exchanger are controlled to be within the same range.

2. The maximum allowable temperature difference test method for a heat exchanger according to claim 1, characterized in that: The increasing the temperature difference in the heat exchanger includes: increasing the temperature difference in the same cross section in the heat exchanger according to a set temperature gradient, and stably operating at each temperature difference gradient value for a set time period.

3. The maximum allowable temperature difference test method for a heat exchanger according to claim 1 or 2, characterized in that: The first medium is air, and the second medium is water.

4. The maximum allowable temperature difference test method for a heat exchanger according to claim 1 or 2, characterized in that: The first medium and the second medium are nitrogen.

5. A heat exchanger maximum allowable temperature difference test device, characterized in that: include: A heat exchanger to be tested, wherein a plurality of temperature detection points are arranged along a medium flow direction of the heat exchanger to be tested; a first heat exchange circuit, wherein the first heat exchange circuit is connected to a first heat exchange side of the tested heat exchanger, a first medium is introduced into the tested heat exchanger, and an output flow rate of the first medium is controlled; a second heat exchange circuit, wherein the second heat exchange circuit is connected to a second heat exchange side of the tested heat exchanger, a second medium is introduced into the tested heat exchanger, and an output flow rate of the first medium is controlled; wherein the first medium and the second medium have a temperature difference; The tested heat exchanger comprises a first temperature sensor group and a second temperature sensor group, wherein the first temperature sensor group and the second temperature sensor group are arranged on the same cross section, the first temperature sensor group is used to detect the first heat exchange side of the tested heat exchanger, and the second temperature sensor group is used to detect the second heat exchange side of the tested heat exchanger; The first temperature sensor group on the same cross-section includes at least two first temperature sensors, and the first temperature sensors are used to measure the temperature of the channel on the first heat exchange side; the second temperature sensor group on the same cross-section includes at least two second temperature sensors, and the second temperature sensors are used to measure the temperature of the channel on the second heat exchange side.

6. The heat exchanger maximum allowable temperature difference test device according to claim 5, characterized in that: The system further includes a controller, which is electrically connected to the first temperature sensor group, the second temperature sensor group, and valves of the first heat exchange circuit and the second heat exchange circuit.

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