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CN-121994834-A - Microchannel flow boiling in-situ measurement method

CN121994834ACN 121994834 ACN121994834 ACN 121994834ACN-121994834-A

Abstract

The invention relates to a microchannel flow boiling in-situ measurement method which comprises the following steps of 1) building a microchannel flow boiling test system (17) for testing, ensuring the tightness and stability of the test system, 2) building a synchrotron radiation X-ray imaging system, 3) performing a pre-test, ensuring that synchrotron radiation X-rays can penetrate through a microchannel and pass through a scintillation crystal (3) and a reflector (4) and then be received by a high-speed camera, 4) performing microchannel flow boiling tests under different test conditions, and after the wall temperature reaches an approximate steady state, shooting the flow boiling phenomenon in the microchannel by using the synchrotron radiation X-ray imaging system, and acquiring the wall temperature and the inlet and outlet pressure by using a temperature pressure sensor in the microchannel flow boiling test system to obtain in-situ measurement results of the wall temperature and the inlet and outlet pressure. Compared with the prior art, the invention has the advantages of solving the problem of view angle limitation existing in the micro-channel flow boiling observation means, and the like.

Inventors

  • WU ZHIJUN
  • PEI ZHONGWEN
  • ZHANG GUANYU
  • LU SHAOAN
  • DENG JUN

Assignees

  • 同济大学

Dates

Publication Date
20260508
Application Date
20260331

Claims (10)

  1. 1. A microchannel flow boiling in situ measurement method, comprising the steps of: 1) A micro-channel flow boiling test system (17) is built for testing, so that the tightness and stability of the test system are ensured; 2) Building a synchrotron radiation X-ray imaging system; 3) Pre-testing is carried out to ensure that the synchrotron radiation X-rays can penetrate through the micro-channel and are received by the high-speed camera after passing through the scintillation crystal (3) and the reflecting mirror (4); 4) And (3) carrying out micro-channel flow boiling tests under different test working conditions, after the wall temperature reaches an approximate steady state, shooting the flow boiling phenomenon in the micro-channel by using the synchrotron radiation X-ray imaging system, and simultaneously acquiring the wall temperature and the inlet and outlet pressure by using a temperature pressure sensor in the micro-channel flow boiling test system to obtain an in-situ measurement result of the wall temperature and the inlet and outlet pressure.
  2. 2. The microchannel flow boiling in situ measurement method according to claim 1, wherein the microchannel flow boiling test system (17) comprises a constant temperature water bath (9), a filter (10), a gear pump (11), a flow meter (12), a preheating section (13), a microchannel radiator test section (14) and a condenser (16).
  3. 3. A microchannel flow boiling in situ measurement method according to claim 2, wherein the microchannel heat sink test section (14) comprises a microchannel heat sink (15), a heating module and a temperature pressure sensor.
  4. 4. A microchannel flow boiling in situ measurement method according to claim 2, characterized in that the synchrotron radiation X-ray imaging system comprises a synchrotron radiation light source (1), a chopper (2), a scintillation crystal (3), a mirror (4) and a high speed camera (5) in sequence along the optical path.
  5. 5. The microchannel flow boiling in situ measurement method as recited in claim 4, wherein the microchannel heat sink sample is located between the chopper (2) and the scintillation crystal (3), and X-rays pass through the chopper (2) and then traverse from the microchannel heat sink sample to the scintillation crystal (3).
  6. 6. A microchannel flow boiling in situ measurement method as claimed in claim 5, wherein the microchannel heat sink (15) has a microchannel width allowing penetration of synchrotron radiation X-rays and a microchannel height less than the window range of synchrotron radiation X-ray imaging.
  7. 7. The micro-channel flow boiling in-situ measurement method according to claim 6, wherein the synchrotron radiation X-ray imaging system further comprises a host computer (6), the host computer (6) is placed outside the laboratory and used for receiving the output signal of the high-speed camera (5) and sending a trigger signal to the signal generator (701), the first signal generator (701) is used for receiving the trigger signal from the host computer (6) and sending a synchronous signal to the high-speed camera (5) and the second signal generator (702), and the second signal generator (702) is used for receiving the synchronous signal from the signal generator first signal generator (701) and sending a control signal to the chopper (2).
  8. 8. The method for in-situ measurement of flow boiling in a microchannel according to claim 7, wherein the specific steps of shooting flow boiling phenomenon in the microchannel by the synchrotron radiation X-ray imaging system are as follows: When the synchronous radiation X-ray imaging system works, after a host machine (6) sends out a trigger signal, the trigger signal is received by a first signal generator (701) to generate two paths of synchronous signals, one path of synchronous signals is sent to a second signal generator (702), the other path of synchronous signals are transmitted to a high-speed camera (5) for shooting, and the second signal generator (702) sends out two paths of control signals with certain delay after receiving the synchronous signals to control a mechanical slow door and a mechanical shutter of a chopper (2); X-rays emitted by the synchrotron radiation light source (1) pass through a microchannel radiator (15) of a microchannel radiator test section (14) after passing through the chopper (2), phase change is generated at a gas-liquid two-phase boundary in the microchannel radiator (15) to form phase contrast imaging, the phase contrast imaging is converted into visible light imaging after passing through the scintillation crystal (3) along a light path, and finally the visible light imaging is received by the high-speed camera (5) through the reflecting mirror (4), and a camera output signal emitted by the high-speed camera (5) is acquired in real time by the host computer (6).
  9. 9. The method for in-situ measurement of micro-channel flow boiling according to claim 8, wherein the specific steps of working condition determination in the process of carrying out micro-channel flow boiling test under different test working conditions are as follows: The heat flux density is controlled through the heating module, the supercooling degree of an inlet is controlled through the constant-temperature water bath box (9) and the preheating section (13), the temperature of an initial cooling working medium is regulated through the constant-temperature water bath box (9), and the temperature of the working medium at the inlet of the micro-channel radiator test section (14) is controlled through the preheating section (13).
  10. 10. The microchannel flow boiling in situ measurement method as set forth in claim 9, wherein the specific steps of testing to ensure tightness and stability of the test system are: The heating module in the micro-channel radiator test section (14), the gear pump (11) drives the cooling working medium in the constant-temperature water bath box (9) to circulate in the micro-channel flow boiling test system for a certain time, all gases in the pipeline are removed, and meanwhile, the running conditions of each part, the pipeline and the sensor of the test system are monitored, so that the system is ensured to run stably, heat normally and have no air leakage phenomenon.

Description

Microchannel flow boiling in-situ measurement method Technical Field The invention relates to the technical field of measurement of micro-channel flow boiling, in particular to a micro-channel flow boiling in-situ measurement method. Background With the continuous improvement of the integration level and performance of electronic devices, the power density of the electronic devices is greatly improved, and the heat dissipation problem of the electronic devices is also more prominent. The micro-channel flow boiling has the advantages of compact structure, large heat exchange area and high heat transfer coefficient, and is a key technology for solving the heat dissipation problem of future electronic equipment. To realize visual research, a microchannel radiator model with a transparent cover plate is currently commonly adopted. However, the key physical properties of the materials, such as thermal conductivity, surface energy, roughness and the like, are obviously different from those of the actually applied metal base materials (such as copper and silicon), so that basic behaviors of bubble nucleation, growth, detachment and the like are deviated, and the observation result cannot truly reflect the physical process in the micro-channel. In addition, the existing visible light observation means has limited visual angle, only the whole channel is macroscopically photographed from the overlook direction, the influence of the channel wall surface in the processes of single bubble nucleation, growth and stretching is difficult to observe, the action relation of gravity and surface tension on the bubble dynamics behavior cannot be analyzed, the influence of the channel surface wettability on the bubble dynamics cannot be directly revealed, and the observation of the flow boiling characteristics of the micro-channel and the analysis of the heat exchange mechanism are restricted. Disclosure of Invention The invention aims to provide a micro-channel flow boiling in-situ measurement method which aims to solve the problem of viewing angle limitation of a micro-channel flow boiling observation means. The aim of the invention can be achieved by the following technical scheme: a microchannel flow boiling in situ measurement method, the method comprising the steps of: 1) A micro-channel flow boiling test system 17 is built for testing, so that the tightness and stability of the test system are ensured; 2) Building a synchrotron radiation X-ray imaging system; 3) Pre-testing is carried out to ensure that the synchrotron radiation X-rays can penetrate through the micro-channel and are received by the high-speed camera after passing through the scintillation crystal 3 and the reflecting mirror 4; 4) And (3) carrying out micro-channel flow boiling tests under different test working conditions, after the wall temperature reaches an approximate steady state, shooting the flow boiling phenomenon in the micro-channel by using the synchrotron radiation X-ray imaging system, and simultaneously acquiring the wall temperature and the inlet and outlet pressure by using a temperature pressure sensor in the micro-channel flow boiling test system to obtain an in-situ measurement result of the wall temperature and the inlet and outlet pressure. Further, the microchannel flow boiling test system 17 comprises a constant temperature water bath 9, a filter 10, a gear pump 11, a flowmeter 12, a preheating section 13, a microchannel radiator test section 14 and a condenser 16. Further, the microchannel heat sink test section 14 includes a microchannel heat sink 15, a heating module, and a temperature pressure sensor. Further, the synchrotron radiation X-ray imaging system includes a synchrotron radiation light source 1, a chopper 2, a scintillator crystal 3, a mirror 4, and a high-speed camera 5 in this order along an optical path. Further, the micro-channel radiator sample is located between the chopper 2 and the scintillation crystal 3, and the X-rays pass through the chopper 2 and then penetrate from the transverse direction of the micro-channel radiator sample to the scintillation crystal 3. Further, the microchannel width of the channel heat sink 15 allows synchrotron radiation X-rays to penetrate, and the microchannel height is smaller than the window range of synchrotron radiation X-ray imaging. Further, the synchrotron radiation X-ray imaging system further comprises a host 6, wherein the host 6 is placed outside the laboratory and is used for receiving the output signal of the high-speed camera 5 and sending a trigger signal to the signal generator 701, the first signal generator 701 is used for receiving the trigger signal from the host 6 and sending a synchronous signal to the high-speed camera 5 and the second signal generator 702, and the second signal generator 702 is used for receiving the synchronous signal from the first signal generator 701 of the signal generator and sending a control signal to the chopper 2. Further, the spe