A high-pressure hydrogen PCHE heat exchanger fatigue test prototype

Abstract

The present invention belongs to the technical field of heat exchanger performance testing, and specifically relates to a high-pressure hydrogen PCHE heat exchanger fatigue test prototype. The test prototype includes two PCHE heat exchanger model machines connected in series, and the two PCHE heat exchanger model machines have the same performance parameters, wherein the first model machine includes: on the basis of the PCHE heat exchanger structure, a straight line is cut along the side of the low-pressure hydrogen side pipe box close to the flow channel area, and an L-shaped edge line is cut along the buffer tank close to the flow channel area and the low-pressure hydrogen side pipe box; the second model machine includes: on the basis of the PCHE heat exchanger structure, a structure is obtained by increasing the size of the high-pressure flow channel radius R. This test prototype is built based on a PCHE heat exchanger with a buffer tank, and a set of test methods are constructed that can simply test the rationality of the PCHE heat exchanger structural design and verify the effect of the buffer tank, and can verify the rationality of the structural design of the part outside the flow channel area of ​​the high-pressure hydrogen PCHE heat exchanger.

Description

Technical Field

[0001] The invention belongs to the technical field of heat exchanger performance testing, and in particular relates to a high-pressure hydrogen PCHE heat exchanger fatigue test prototype. Technical Background

[0002] A microchannel heat exchanger (PCHE) is a heat exchanger fabricated by etching heat exchange channels into thin plates and then welding them together via diffusion bonding. This heat exchanger boasts compact structure, high heat transfer efficiency, and high-temperature and high-pressure resistance. It has broad applications in LNG floating storage and regasification, Brayton cycle power generation (such as nuclear and thermal power), and hydrogen production, storage, and charging.

[0003] High-pressure hydrogen PCHE heat exchangers used in hydrogen filling stations can operate at maximum pressures of up to 90 MPa, often accompanied by frequent pressure fluctuations. This poses a risk of fatigue failure for these PCHE heat exchangers. However, the suitability of the steel plate materials and diffusion-welded joints used to manufacture these heat exchangers for use in hydrogen environments exceeding 90 MPa, as well as their fatigue performance in such environments, are still under investigation and lack safety assurance. Furthermore, defects in the processing and manufacturing processes could potentially impact the safety of these heat exchangers during use.

[0004] It is very necessary to provide a test prototype to simply and quickly confirm the fatigue performance of the designed PCHE heat exchanger under test conditions, thereby confirming the rationality of the design. Summary of the Invention

[0005] The present invention is to solve the above problems and provides a high-pressure hydrogen PCHE heat exchanger fatigue test prototype.

[0006] The present invention adopts the following technical solutions:

[0007] A high-pressure hydrogen PCHE heat exchanger fatigue test prototype includes two PCHE heat exchanger models connected in series. The two PCHE heat exchanger models have the same design parameters. The first model includes: a structure obtained by linearly cutting along a side of a low-pressure hydrogen side pipe box near the flow channel area based on the PCHE heat exchanger structure, and cutting along an L-shaped edge line of a buffer tank near the flow channel area and the low-pressure hydrogen side pipe box; the second model includes: a structure obtained by increasing the size of the high-pressure flow channel radius R based on the PCHE heat exchanger structure;

[0008] The series connection is as follows: the inlet of the first model machine is connected to the air inlet of the hydrogen charging and discharging test system, the outlet of the first model machine is connected to the inlet of the second model machine, and the outlet of the second model machine is connected to the air outlet of the hydrogen charging and discharging test system.

[0009] Preferably, in the PCHE heat exchanger model machine, high-pressure flow channels are arranged closely in a "J" shape in the flow channel area on the high-pressure hydrogen side plate, and buffer flow channels are arranged at the same position on both sides of the flow channel area on the high-pressure hydrogen side plate and the low-pressure hydrogen side plate. The buffer flow channels are perpendicular to the turning gaps produced by the "J" shape arrangement of the high-pressure flow channels, and the buffer flow channels are overlapped to form buffer grooves; the high-pressure hydrogen side pipe box is arranged on the same side as the buffer flow channel and the setting positions avoid each other, and the low-pressure hydrogen side pipe boxes are arranged on both sides of the flow channel area and in a cross shape on the high-pressure hydrogen side pipe box.

[0010] Preferably, a release channel is provided between the buffer tank and the high-pressure flow channel region of each high-pressure hydrogen side plate, and the release channel is arranged in a turning gap formed by the S-shaped arrangement of the high-pressure flow channels.

[0011] Preferably, in the PCHE heat exchanger model, the distance between the central axes of adjacent high-pressure flow channels is denoted as S1, and the distance between the buffer tank and the closest flow channel region is denoted as S2, and S2 satisfies S2≥0.5S1.

[0012] Preferably, in the second model machine, the principle of increasing the size of the high-pressure flow channel radius R is: under the premise of ensuring that the flow channel ribs do not suffer primary stress damage, through finite element simulation testing, the fatigue resistance of the second model machine is reduced to less than 80% of the original structure.

[0013] The beneficial effects of the present invention are:

[0014] To address the potential for hydrogen leakage during use in PCHE heat exchangers due to material degradation and fracture under high-pressure hydrogen, fatigue fracture caused by cyclic pressure loads, or damage due to manufacturing defects, a PCHE heat exchanger with a buffer tank was designed. This test prototype was constructed based on a PCHE heat exchanger with a buffer tank, establishing a test method that can simply test the rationality of the PCHE heat exchanger's structural design and verify the effectiveness of the buffer tank.

[0015] This test prototype consists of a first and second model connected in series. Fatigue testing can be performed by repeatedly inflating and depressurizing the first and second models. The first test model retains only the basic PCHE heat exchanger structure, including the high-pressure hydrogen side plates, low-pressure hydrogen side plates, and end plates, to eliminate the impact of materials outside the plate flow channel area on the flow channel structural strength and fatigue performance, thereby facilitating a better comparison of test results with theoretical predictions. Based on the newly designed PCHE structure, the second test model maintains the same spacing between the high-pressure flow channels and increases only the flow channel radius, reducing the flow channel ribs. This increases stress and weakens the fatigue performance of the high-pressure hydrogen side plates. Consequently, the second test model breaks during fatigue testing earlier than the first test model, verifying the rationality of the structural design outside the high-pressure hydrogen PCHE heat exchanger flow channel area. After the second test model breaks, hydrogen leaks into the buffer tank, further verifying the effectiveness of the buffer tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic structural diagram of the high-pressure hydrogen PCHE heat exchanger used in the present invention;

[0017] Figure 2 This is a schematic diagram of the structure of the high-pressure hydrogen side plate in the high-pressure hydrogen PCHE heat exchanger;

[0018] Figure 3 This is a schematic diagram of the structure of the low-pressure hydrogen side plates in the high-pressure hydrogen PCHE heat exchanger;

[0019] Figure 4 、 Figure 5 This is a schematic diagram of the first model machine after the plate is cut off, and the shaded part in the figure is the cut-off area;

[0020] Figure 6 for Figure 2 The enlarged view of part Ⅰ, in which a represents the flow channel rib;

[0021] Figure 7 Schematic diagram of the flow channel radius R in the second model machine.

[0022] The meanings of the symbols in the figure are as follows:

[0023] 11-upper end plate 111-fluid inlet and outlet 12-heat exchange core 13-lower end plate

[0024] 20- High-pressure hydrogen side plate 21- High-pressure hydrogen side pipe box 22- High-pressure flow channel

[0025] 30- low-pressure hydrogen side plate 31- low-pressure hydrogen side pipe box 32- low-pressure flow channel

[0026] 40-buffer tank 41-release channel 42-leak detection interface

[0027] a- channel rib b1 / b2- vertical distance between the buffer channel and the high-pressure channels on both sides

[0028] S1 - distance between the center axes of adjacent high-pressure flow channels S2 - distance between the buffer tank and the flow channel area closest to it S3 - distance between the high-pressure hydrogen side pipe box and the side of the low-pressure hydrogen side pipe box close to the flow channel area S4 - vertical distance between the high-pressure hydrogen side pipe box and the edge of the nearest side of the buffer tank DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in more detail below with reference to the embodiments:

[0030] like Figure 1-Figure 3 As shown, a high-pressure hydrogen PCHE heat exchanger includes an upper end plate 11, a heat exchange core 12 and a lower end plate 13 arranged in sequence from top to bottom. The heat exchange core 12 is composed of high-pressure hydrogen side plates 20 and low-pressure hydrogen side plates 30 stacked alternately, and the side where the heat exchange core 12 is connected to the upper end plate 11 and the lower end plate 13 is set as a low-pressure hydrogen side plate 30.

[0031] The centers of the high-pressure hydrogen side plates 20 and the low-pressure hydrogen side plates 30 are set as the flow channel area, and the heat exchange core 12 is arranged with high-pressure hydrogen side pipe boxes 21 on any two opposite sides outside the flow channel area, and low-pressure hydrogen side pipe boxes 31 on the other two opposite sides.

[0032] High-pressure flow channels 22 are arranged in the flow channel area on the high-pressure hydrogen side plate 20, and all high-pressure flow channels 22 are connected through the high-pressure hydrogen side pipe box 21; low-pressure flow channels 32 are arranged in the flow channel area on the low-pressure hydrogen side plate 30, and all low-pressure flow channels 32 are connected through the low-pressure hydrogen side pipe box 31.

[0033] Furthermore, the high-pressure hydrogen side pipe box 21 includes a high-pressure inlet pipe box and a high-pressure outlet pipe box, the high-pressure inlet pipe box is connected to the inlet end of the high-pressure flow channel 22, and the high-pressure outlet pipe box is connected to the outlet end of the high-pressure flow channel 22. The low-pressure hydrogen side pipe box 31 includes a low-pressure inlet pipe box and a low-pressure outlet pipe box, the low-pressure inlet pipe box is connected to the inlet end of the low-pressure flow channel 32, and the low-pressure outlet pipe box is connected to the outlet end of the low-pressure flow channel 32. The low-pressure hydrogen side pipe box 31 and the high-pressure hydrogen side pipe box 21 are arranged in positions that avoid each other.

[0034] The upper end plate 11 is provided with fluid inlets and outlets 111, including a hydrogen inlet and outlet respectively connected to the high-pressure inlet pipe box and the high-pressure outlet pipe box, and a low-pressure fluid inlet and outlet respectively connected to the low-pressure inlet pipe box and the low-pressure outlet pipe box. The lower end plate 13 is used to close the bottom ends of the high-pressure inlet pipe box and the high-pressure outlet pipe box.

[0035] In the high-pressure hydrogen side plate 20, the high-pressure flow channels 22 are closely arranged in an "X" shape. Buffer flow channels are arranged on both sides of the flow channel area of ​​the high-pressure hydrogen side plate 20, parallel to the length of the plate. The buffer flow channels are perpendicular to the turning gaps created by the "X" shape arrangement of the high-pressure flow channels 22. Buffer flow channels are arranged on the low-pressure hydrogen side plate 30 in the same position as those opened on the high-pressure hydrogen side plate 20. The upper and lower layers of buffer flow channels overlap to form a buffer groove 40, the top and bottom of which are respectively closed by the upper end plate 11 and the lower end plate 13.

[0036] The buffer tank 40 is also connected to the high-pressure flow channel 22 area of ​​each high-pressure hydrogen side plate 20 through a release channel 41. A release channel 41 is set between the buffer tank 40 and the high-pressure flow channel 22 area of ​​each high-pressure hydrogen side plate 20. The release channel 41 is arranged in the turning gap generated by the "J" arrangement of the high-pressure flow channel 22 and is separated from the interior of the high-pressure flow channel 22.

[0037] The cross section of the release channel 41 is any one of semicircular, rectangular, triangular, and semi-elliptical.

[0038] In this high-pressure hydrogen PCHE heat exchanger, let S1 be the distance between the center axes of adjacent high-pressure flow channels, and S2 be the distance between the buffer tank 40 and the flow channel area closest to it. Then S2 satisfies S2 ≥ 0.5S1. Let S3 be the distance between the high-pressure hydrogen side pipe box 21 and the low-pressure hydrogen side pipe box 31 on the side close to the flow channel area, and S4 be the vertical distance between the high-pressure hydrogen side pipe box 21 and the edge closest to the buffer tank 40. The distances S3 and S4 should comply with the relevant design standards for pressure vessels (JB4732-1995). Let a be the width of the flow channel ribs of adjacent high-pressure flow channels 22, and b1 and b2 be the vertical distances between the release channel 41 and the high-pressure flow channels 22 on both sides, respectively. Then b1 = b2, and b1 + b2 > a.

[0039] Based on the above-mentioned high-pressure hydrogen PCHE heat exchanger, a high-pressure hydrogen PCHE heat exchanger fatigue test prototype required by the present invention is designed.

[0040] like Figure 4-Figure 6 As shown, the test prototype includes two PCHE heat exchanger models connected in series. The two PCHE heat exchanger models have the same design parameters. The first model includes: a structure obtained by linearly cutting along one side of the low-pressure hydrogen side pipe box 31 close to the flow channel area based on the PCHE heat exchanger structure, and cutting along the L-shaped edge line of the buffer tank 40 close to the flow channel area and the low-pressure hydrogen side pipe box 31; the second model includes: a structure obtained by increasing the size of the high-pressure flow channel radius R based on the PCHE heat exchanger structure;

[0041] The above series connection is as follows: the inlet of the first model machine is connected to the air inlet of the hydrogen charging and discharging test system, the outlet of the first model machine is connected to the inlet of the second model machine, and the outlet of the second model machine is connected to the air outlet of the hydrogen charging and discharging test system.

[0042] The principle behind increasing the high-pressure flow channel radius R is to ensure that the flow channel rib a is not damaged by primary stress (i.e., stress experienced upon connection to the hydrogen charging and discharging test system). Finite element simulation testing has been conducted to reduce the fatigue resistance of the second prototype to less than 80% of the original structure. For undetermined prototypes, a single increase in the R radius of 0.1 mm can be used as a guideline for designing and testing test prototypes, based on demand.

[0043] Fatigue tests were conducted on the prototypes to confirm the rationality of the plate structure design and the effectiveness of the leakage grooves. The fatigue test process involved filling the first and second prototypes with hydrogen, releasing the pressure after reaching the set pressure, and then filling again, repeating the filling and releasing process.

[0044] During testing, the outlet of the second model was blocked. During the cyclic test, for heat exchangers that met design requirements, the increased radius R of the high-pressure flow channel in the second model reduced the flow channel rib a, weakening the heat exchanger's fatigue resistance and causing it to break before the first model, validating the rationality of the structural design outside the flow channel area. Simultaneously, the flow channel in the second model broke, and the leaked hydrogen flowed into the buffer tank 40 through the release channel 41, demonstrating the effectiveness of the buffer tank 40.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-pressure hydrogen PCHE heat exchanger fatigue test prototype, characterized in that: The invention comprises two PCHE heat exchanger model machines connected in series, and the design parameters of the two PCHE heat exchanger model machines are the same, wherein the first model machine comprises: a structure obtained by linearly cutting along one side of the low-pressure hydrogen side pipe box (31) close to the flow channel area and cutting along the L-shaped edge line of the buffer tank (40) close to the flow channel area and the low-pressure hydrogen side pipe box (31) based on the PCHE heat exchanger structure; and the second model machine comprises: a structure obtained by increasing the size of the high-pressure flow channel radius R based on the PCHE heat exchanger structure; The series connection is as follows: the inlet of the first model machine is connected to the air inlet of the hydrogen charging and discharging test system, the outlet of the first model machine is connected to the inlet of the second model machine, and the outlet of the second model machine is connected to the air outlet of the hydrogen charging and discharging test system; In the PCHE heat exchanger model, high-pressure flow channels (22) are arranged closely in a "J" shape in the flow channel area on the high-pressure hydrogen side plate (20), and buffer flow channels are arranged at the same position on both sides of the flow channel area on the high-pressure hydrogen side plate (20) and the low-pressure hydrogen side plate (30). The buffer flow channels are perpendicular to the turning gaps formed by the "J" shape arrangement of the high-pressure flow channels (22), and the buffer flow channels are overlapped to form a buffer groove (40).

2. A high-pressure hydrogen PCHE heat exchanger fatigue test prototype according to claim 1, characterized in that: The high-pressure hydrogen side pipe box (21) is arranged on the same side as the buffer flow channel and their arrangement positions are avoided. The low-pressure hydrogen side pipe box (31) is arranged on both sides of the flow channel area and is in a cross shape with the high-pressure hydrogen side pipe box (21).

3. A high-pressure hydrogen PCHE heat exchanger fatigue test prototype according to claim 1, characterized in that: One or more release channels (41) are provided between the buffer tank (40) and the high-pressure flow channel (22) region of each high-pressure hydrogen side plate (20), and the inlet of the release channel (41) is arranged in the turning gap generated by the "X" arrangement of the high-pressure flow channel (22).

4. A high-pressure hydrogen PCHE heat exchanger fatigue test prototype according to claim 1, characterized in that: In the PCHE heat exchanger model, the distance between the central axes of adjacent high-pressure flow channels (22) is denoted as S1, and the distance between the buffer tank (40) and the closest flow channel region is denoted as S2, and S2 satisfies S2≥0.5S1.

5. A high-pressure hydrogen PCHE heat exchanger fatigue test prototype according to claim 1, characterized in that: In the second model machine, the principle of increasing the size of the high-pressure flow channel radius R is: under the premise of ensuring that the flow channel ribs do not suffer primary stress damage, through finite element simulation testing, the fatigue resistance of the second model machine is reduced to less than 80% of the original structure.

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