A flow instability measurement system and instability type identification method

Abstract

The invention discloses a flow instability measurement system and an instability type identification method, comprising: a refrigerant storage tank, a semiconductor refrigeration plate, a heating plate, a supercooler, a micro magnetic drive pump, a first pressure sensor, a first differential pressure sensor, a buffer, a second pressure sensor, a filter, a volume flow meter, a second differential pressure sensor, a preheating section inlet pressure sensor, a preheating section inlet thermocouple, a preheating section, a preheating section DC power supply, a preheating section differential pressure sensor, an experimental section inlet thermocouple, a smooth copper tube, an experimental section, an experimental section DC power supply, an experimental section thermocouple, an experimental section outlet thermocouple, an experimental section differential pressure sensor, an experimental section outlet pressure sensor, a condenser, a water tank, a large flow gear pump, a transparent polytetrafluoroethylene tube and a water pipe; the invention has the function of measuring the pressure changes at the inlets and outlets of each important component in the system, and further optimizing the local part of the system according to the pressure drop of each important component, thereby improving the stability of the system.

Description

Technical Field

[0001] The invention belongs to the technical field of reactor thermal hydraulics, and in particular relates to a flow instability measurement system and an instability type identification method. Background Art

[0002] Flow boiling is often used to dissipate heat for electronic components under high heat flux density because of its advantage of high thermal efficiency. However, the gas-liquid two-phase flow during flow boiling can cause system instability. The oscillations of pressure, mass flow rate and temperature caused by these instabilities can cause mechanical vibrations, temperature oscillations and interference with the control system, thereby reducing the thermal efficiency and safety of the system. Therefore, how to improve system stability and correctly identify the type of instability is an important task. Existing flow boiling systems have more or less instability phenomena, and the factors that cause this instability are related to the type of instability. Since pressure drop instability and density wave instability are the two most common types of flow instability, the identification of the instability type of the present invention focuses on the identification of pressure drop instability and density wave instability. Among them, pressure drop instability is mainly related to the compressible space and flow pulsation in the system; the main mechanism for the generation and propagation of density wave instability is the propagation delay caused by disturbances and the feedback of import and export parameter adjustments.

[0003] Therefore, how to design a flow instability measurement system and an instability type identification method to improve system instability and accurately identify the instability types occurring in the system is a topic that scholars from all over the world need to study in depth. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a flow instability measurement system and an instability type identification method to solve the problems of unreliable flow instability system measurement results and low instability type identification accuracy in the prior art. The present invention measures the proportion of the pressure at the inlet and outlet of each important component in the system to the total pressure fluctuation of the system, and can appropriately add a throttle valve after the component with large pressure fluctuation to reduce the compressible space upstream of the component, thereby improving the stability and reliability of the system. The present invention accurately identifies the instability type existing in the system by combining multiple identification methods.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A flow instability measurement system of the present invention comprises: a refrigerant storage tank, a semiconductor refrigeration sheet, a heating sheet, a supercooler, a micro magnetic drive pump, a first pressure sensor, a first differential pressure sensor, a buffer, a second pressure sensor, a filter, a volume flow meter, a second differential pressure sensor, a preheating section inlet pressure sensor, a preheating section inlet thermocouple, a preheating section, a preheating section DC power supply, a preheating section differential pressure sensor, an experimental section inlet thermocouple, a smooth copper tube, an experimental section, an experimental section DC power supply, an experimental section thermocouple, an experimental section outlet thermocouple, an experimental section differential pressure sensor, an experimental section outlet pressure sensor, a condenser, a water tank, a large flow gear pump, a transparent polytetrafluoroethylene tube and a water pipe; the semiconductor refrigeration sheet and the heating sheet are fixed above and below the refrigerant storage tank respectively; the refrigerant storage tank, the supercooler, the micro magnetic drive pump, the buffer, the filter, the volume flow meter, the preheating section, the smooth copper tube, the experimental section, the smooth copper tube and the condenser are connected in sequence through a transparent polytetrafluoro tube; the first pressure sensor and the first differential pressure sensor and the micro magnetic drive pump, the second pressure sensor and the buffer, the second differential pressure sensor and the volume flow meter, the preheating section inlet pressure sensor and the preheating section differential pressure sensor and the preheating section, the experimental section differential pressure sensor and the experimental section outlet pressure sensor and the experimental section are all connected through a transparent polytetrafluoro tube; the positive and negative poles of the preheating section DC power supply are connected to the wires wound at both ends of the preheating section through terminals, and the positive and negative poles of the experimental section DC power supply are connected to the wires wound at both ends of the experimental section through terminals; the pins of the experimental section inlet thermocouple and the experimental section outlet thermocouple are connected to the outer wall of the smooth copper tube, and the pins of the preheating section inlet thermocouple are connected to the preheating section; the pins of the experimental section thermocouple are filled and bonded to the grooves opened on the experimental section tube wall; the subcooler, condenser, water tank and large-flow gear pump are connected in sequence through water pipes.

[0007] Furthermore, the semiconductor cooling plate and the heating plate are fixed to the refrigerant storage tank by means of cable ties.

[0008] Furthermore, the pins of the experimental section inlet thermocouple and the experimental section outlet thermocouple are bonded to the outer wall of the smooth copper tube by means of thermal insulation tape.

[0009] Furthermore, the pins of the thermocouple at the inlet of the preheating section are bonded to the preheating section by means of an insulating tape.

[0010] Furthermore, the preheating section and the experimental section are made in the same way, with a copper tube as the substrate, and the first insulating tape, the resistance wire, the second insulating tape, the insulating tape and the thermal insulation cotton are evenly wound around the copper tube from the inside to the outside.

[0011] Furthermore, the refrigerant storage tank, subcooler, micro magnetic drive pump, buffer, filter, volume flow meter, preheating section, smooth copper tube, experimental section and condenser in the system constitute a refrigerant circulation system; the subcooler, condenser, water tank and large-flow gear pump constitute a cooling water circulation system; the refrigerant and cooling water flowing through the subcooler are in countercurrent form.

[0012] Furthermore, the maximum flow rate of the micro magnetic drive pump is 2.4 L / min; the maximum flow rate of the large flow gear pump is 40 L / min.

[0013] The present invention provides an instability type identification method for a flow instability measurement system, based on the above system, comprising the following steps:

[0014] 1) Given system pressure P s-out , heating power q of the experimental section, subcooling degree ΔT at the entrance of the experimental section in , by reducing the time-averaged volume flow in the system To the preset value v 1 、v 2 …v n , using the recorded transient volume flow q v Calculate the corresponding time-averaged mass flow rate Simultaneously monitor the time-averaged pressure drop within the test section Draw the pressure drop-mass flow rate characteristic curve corresponding to the experimental section under the time average value;

[0015] 2) Collect the transient value P of the current test section outlet pressure of the system out And the transient pressure drop ΔP in the experimental section, and calculate the transient saturation pressure P in the experimental section sat , combined with the transient saturation pressure P sat The time-averaged saturation pressure in the experimental section is calculated Acquisition system current test section outlet thermocouple transient temperature T out ;

[0016] 3) Preliminarily determine the average mass flow rate at different times through the experimental section pressure drop-mass flow rate characteristic curve drawn in step 1) The corresponding instability type; using the current transient pressure P of the test section outlet of the system collected in step 2) out and the transient saturation pressure P in the experimental section sat , combined with the time-averaged saturation pressure in the experimental section calculated in step 2) The transient pressure amplitude ratio P of the experimental section is calculated. test Combined with the transient pressure drop ΔP in the experimental section collected in step 2) and the transient temperature T of the thermocouple at the outlet of the current experimental section of the system out, draw the curves of the transient pressure amplitude ratio of the experimental section and the transient temperature of the thermocouple at the outlet of the experimental section changing with time, and the curves of the transient mass flow rate of the experimental section and the transient pressure drop of the experimental section changing with time;

[0017] 4) According to the parameters (P test , T out The fluctuation amplitude and period of density wave (G, ΔP) over time can be used to further identify the type of instability generated in the system; based on the calculated period t of density wave instability, the type of instability generated in the system can be finally identified.

[0018] Beneficial effects of the present invention:

[0019] 1. Using a combination of pressure sensors and differential pressure sensors to measure the inlet and outlet pressures of each important component in the system can avoid the irrationality of using only pressure sensors to measure the inlet and outlet pressures of each important component (that is, when the inlet and outlet pressure differential of an important component is small, if pressure sensors are used to measure the pressure at both the inlet and outlet, the outlet pressure may be greater than the inlet pressure due to the measurement error of the pressure sensor, resulting in unreasonable measurement results).

[0020] 2. The smooth copper tube and the experimental section are connected by a transparent polytetrafluoroethylene tube, and the inlet and outlet thermocouples of the experimental section are respectively bonded to independent smooth copper tubes. This can effectively avoid the influence of the inductance generated by the energized experimental section on the inlet and outlet temperatures, making the measurement accuracy of the system higher.

[0021] 3. The system pressure is always kept near the preset value by using a combination of coarse and fine adjustment. Coarse adjustment: adjusting the speed of the large-flow gear pump can change the cooling water flow into the condenser, realize the gas-liquid two-phase condensation rate of the refrigerant, and then adjust the system pressure; fine adjustment: adjust the power of the semiconductor cooling plate and heating plate installed at the upper and lower ends of the opposite sides of the refrigerant storage tank to fine-tune the system pressure.

[0022] 4. The speed and accuracy of identifying unstable types can be effectively improved by combining the experimental section pressure drop-mass flow rate characteristic curve, the experimental section transient pressure amplitude ratio and the experimental section outlet thermocouple transient temperature change with time curve, and the experimental section transient mass flow rate and the experimental section transient pressure drop change with time curve. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a flow instability measurement system diagram of the present invention;

[0024] Figure 2 It is a schematic diagram of the experimental section structure of the present invention;

[0025] Figure 3It is a graph of pressure drop-mass flow rate characteristic of the experimental section of the present invention;

[0026] Figure 4a It is a graph showing the transient pressure amplitude ratio of the experimental section with unstable pressure drop and the transient temperature of the thermocouple at the outlet of the experimental section changing with time;

[0027] Figure 4b is a graph showing the transient pressure amplitude ratio of the experimental section with density wave instability and the transient temperature of the thermocouple at the outlet of the experimental section changing with time;

[0028] Figure 5a It is a curve diagram of the transient mass flow rate and the transient pressure drop of the experimental section with unstable pressure drop versus time;

[0029] Figure 5b is a graph showing the transient mass flow rate and transient pressure drop of the experimental section with density wave instability versus time;

[0030] In the figure: refrigerant liquid storage tank 1, semiconductor refrigeration plate 2, heating plate 3, supercooler 4, micro magnetic drive pump 5, first pressure sensor 6, first differential pressure sensor 7, buffer 8, second pressure sensor 9, filter 10, volume flow meter 11, second differential pressure sensor 12, preheating section inlet pressure sensor 13, preheating section inlet thermocouple 14, preheating section 15, preheating section DC power supply 16, preheating section differential pressure sensor 17, experimental section inlet thermocouple 18, smooth copper tube 19, experimental section 20, experimental section DC power supply 21, experimental section thermocouple 22, experimental section outlet thermocouple 23, experimental section differential pressure sensor 24, experimental section outlet pressure sensor 25, condenser 26, water tank 27, large flow gear pump 28, transparent polytetrafluoroethylene tube 29, water pipe 30, copper tube 201, first insulating tape 202, resistance wire 203, second insulating tape 204, thermal insulation tape 205, thermal insulation cotton 206. DETAILED DESCRIPTION

[0031] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments and drawings. The contents mentioned in the implementation modes are not intended to limit the present invention.

[0032] Reference Figure 1As shown, a flow instability measurement system of the present invention comprises: a refrigerant storage tank 1, a semiconductor refrigeration plate 2, a heating plate 3, a supercooler 4, a micro magnetic drive pump 5, a first pressure sensor 6, a first differential pressure sensor 7, a buffer 8, a second pressure sensor 9, a filter 10, a volume flow meter 11, a second differential pressure sensor 12, a preheating section inlet pressure sensor 13, a preheating section inlet thermocouple 14, a preheating section 15, a preheating section DC power supply 16, a preheating section differential pressure sensor 17, an experimental section inlet thermocouple 18, a smooth copper tube 19, an experimental section 20, an experimental section DC power supply 21, an experimental section thermocouple 22, an experimental section outlet thermocouple 23, an experimental section differential pressure sensor 24, an experimental section outlet pressure sensor 25, a condenser 26, a water tank 27, a large flow gear pump 28, a transparent polytetrafluoroethylene tube 29 and a water pipe 30;

[0033] The semiconductor cooling plate 2 and the heating plate 3 are arranged on the upper and lower sides of the refrigerant storage tank 1 respectively, for fine-tuning the system pressure. Among them, the semiconductor refrigeration chip 2 is installed above the refrigerant storage tank 1, and the gas in the refrigerant storage tank 1 is cooled to liquefy the gas, thereby reducing the system pressure (if the semiconductor refrigeration chip 2 is installed below the storage tank, the liquid below the refrigerant storage tank 1 is directly cooled, and the density of the refrigerant liquid in the storage tank is almost unchanged, and the function of regulating pressure cannot be achieved); the heating chip 3 is generally installed below the side near the bottom of the refrigerant storage tank 1, and the liquid working medium is vaporized and expanded by heating the refrigerant liquid, thereby increasing the system pressure (if the heating chip 3 is installed above the refrigerant storage tank 1, the gas above the storage tank is directly heated, and the system pressure changes slightly, and the function of regulating pressure cannot be achieved); the subcooler 4 is installed between the refrigerant storage tank 1 and the micro magnetic drive pump 5, and the refrigerant and cooling water flowing through the subcooler 4 in a countercurrent manner cool the refrigerant entering the micro magnetic drive pump 5 to a supercooling degree of more than 20°C, which can better prevent the liquid refrigerant from partially evaporating in the micro magnetic drive pump 5 and produce a more stable and effective volume flow control.

[0034] The first pressure sensor 6 and the first differential pressure sensor 7 are used to measure the inlet pressure and differential pressure of the micro magnetic drive pump 5, and the outlet pressure of the micro magnetic drive pump 5 is calculated by collecting the inlet pressure and differential pressure. The measurement method combining the pressure sensor and the differential pressure sensor can effectively avoid the irrationality of the pressure measurement value caused by the accuracy of the pressure sensor. This measurement method combining the pressure sensor and the differential pressure sensor is also applicable to other components in the system, including: buffer 8, volume flow meter 11, preheating section 15 and experimental section 20.

[0035] The filter 10 is installed between the buffer 8 and the volume flow meter 11 to filter out solid particles mixed in the refrigeration (the source of the solid particles may be corrosion of the internal structure of the system components), to prevent the solid particles from entering the volume flow meter 11 and wearing out the meshing gears or blocking the flow of liquid refrigerant.

[0036] The preheating section 15 and the experimental section 20 are powered by a DC power supply with more stable power supply performance; the experimental section inlet thermocouple 18 and the experimental section outlet thermocouple 23 are respectively bonded to the smooth copper tube 19, and the smooth copper tube 19 and the experimental section 20 are connected by a transparent polytetrafluoroethylene tube 29, so that the inductance and electromagnetic effects generated by the experimental section 20 can be prevented from being transmitted to the smooth copper tube 19, thereby causing a large jump in the measured temperature values ​​of the experimental section inlet thermocouple 18 and the experimental section outlet thermocouple 23.

[0037] The refrigerant and cooling water circulating in the condenser 26 are counter-currently liquefied, and the amount of cooling water entering the condenser 26 is controlled by adjusting the rotation speed of the large-flow gear pump 28, thereby controlling the refrigerant liquefaction rate. Since there is a phase change in this process, the system pressure will change, so this process can achieve the function of roughly adjusting the system pressure. The large-flow gear pump 28 has a maximum flow of 40L / min and a large head, which avoids the phenomenon that the small-flow gear pump cannot pump the cooling water in the water tank 27.

[0038] like Figure 2 As shown, the experimental section 20 includes: a copper tube 201, a first insulating tape 202, a resistance wire 203, a second insulating tape 204, an insulating tape 205, and a thermal insulation cotton 206, and the copper tube 201 is used as a substrate, and the first insulating tape 202, the resistance wire 203, the second insulating tape 204, the insulating tape 205 and the thermal insulation cotton 206 are evenly wound on the copper tube 201 from the inside to the outside.

[0039] The present invention provides an instability type identification method for a flow instability measurement system, based on the above system, comprising the following steps:

[0040] 1) Given system pressure P s-out , heating power q of the experimental section, subcooling degree ΔT at the entrance of the experimental section in , by reducing the time-averaged volume flow in the system to a series of preset values ​​v 1 、v 2 …v n , and record the transient volume flow rate q each time it decreases to near the preset value v The data is 5 minutes long, and the average volume flow rate in each data recording period is calculated by formula (1): And use formula (2) to calculate the time-averaged volume flow rate The corresponding time-averaged mass flow rate Simultaneously monitor the time-averaged pressure drop within the test section The pressure drop-mass flow rate characteristic curve corresponding to the experimental section under the time average value is drawn. Among them, the time average volume flow rate is calculated using formula (1): The time-averaged mass flow rate in formula (2) is is the time-averaged volume flow rate Parameters related to the refrigerant fluid density ρ and the cross-sectional area A of the refrigerant flow pipe are used to calculate the time-averaged mass flow rate. The time-averaged volume flow rate needs to be The unit ml / min is converted into the international unit m 3 / s.

[0041] like Figure 3 As shown in the figure, the operation steps for drawing the pressure drop-mass flow rate characteristic curve of the experimental section are as follows: Given the system outlet pressure P out , heating power q of the experimental section, subcooling degree ΔT at the entrance of the experimental section in By gradually reducing the speed of the micro magnetic drive pump, the time-averaged mass flow rate in the system is gradually reduced. Measure the time-averaged pressure drop within the experimental section Draw the experimental section pressure drop-mass flow rate characteristic curve corresponding to the time average value; pressure drop instability usually occurs in the negative slope area of ​​the experimental section pressure drop-mass flow rate characteristic curve; there are many possible areas where density wave instability occurs, usually appearing in the high dryness area, that is, the positive slope area of ​​the pressure drop-mass flow rate characteristic curve, the negative slope area near the starting point of flow instability, or superimposed on the pressure drop instability; the formula is as follows:

[0042]

[0043]

[0044] In the formula, is the time-averaged value of mass flow rate, in kg / m 2 s;q v is the instantaneous value of the volume flow rate of the micro magnetic drive pump, in ml / min; ρ is the density of the refrigerant fluid, in kg / m 3 ; A is the cross-sectional area of ​​the refrigerant flow pipe, in m 2 .

[0045] 2) Collect the transient value P of the current test section outlet pressure of the system out (At a given system pressure P s-out The transient saturation pressure P in the experimental section is calculated by sat , combined with the transient saturation pressure Psat The time-averaged saturation pressure in the experimental section is calculated Acquisition system current test section outlet thermocouple transient temperature T out ;

[0046] 3) The mean mass flow rate at different times can be preliminarily determined by the experimental section pressure drop-mass flow rate characteristic curve drawn in step 1). The corresponding instability type; using the current transient pressure P of the test section outlet of the system collected in step 2) out and the transient saturation pressure P in the experimental section sat , combined with the time-averaged saturation pressure in the experimental section calculated in step 2) The transient pressure amplitude ratio P of the experimental section is calculated. test Combined with the transient pressure drop ΔP in the experimental section collected in step 2) and the transient temperature T of the thermocouple at the outlet of the current experimental section of the system out , draw the curves of the transient pressure amplitude ratio of the experimental section and the transient temperature of the thermocouple at the outlet of the experimental section changing with time, and the curves of the transient mass flow rate of the experimental section and the transient pressure drop of the experimental section changing with time;

[0047] 4) According to the parameters (P test , T out The fluctuation amplitude and period of density wave (G, ΔP) over time can be used to further identify the type of instability generated in the system; based on the calculated period t of density wave instability, the type of instability generated in the system can be finally identified.

[0048] like Figure 4a and Figure 4b As shown, the transient value P of the outlet pressure of the experimental section is collected. out and the transient pressure drop ΔP in the experimental section, and use formula (3) to calculate the transient saturation pressure P in the experimental section: sat , and according to the transient saturation pressure P sat Calculate the time-averaged saturation pressure in the experimental section Collect the transient temperature T of the thermocouple at the outlet of the experimental section out ; P collected during the experimental period sat and After normalization, the transient pressure amplitude ratio P of the experimental section required for identifying the instability type is obtained. test ; The formula is as follows:

[0049]

[0050]

[0051] Combined with the transient pressure amplitude ratio P calculated by formula (4), test , we can get the transient pressure amplitude ratio Ptest and the transient temperature T of the thermocouple at the outlet of the experimental section out The curve of the change with time; the transient temperature of the six thermocouples on the experimental section is collected to monitor the temperature change of each local area in the experimental section; Figure 4a and Figure 4b It can be seen that when the voltage drop instability occurs, P test , T sat and T out The amplitude and period of fluctuations over time are large; when density wave instability occurs, P test , T sat and T out The amplitude and period of fluctuations over time are smaller.

[0052] like Figure 5a and Figure 5b As shown, the transient mass flow rate G is collected by the transient volume flow meter q v The numerical value is calculated using formula (5), and the formula is as follows:

[0053]

[0054] Depend on Figure 5a and Figure 5b It can be seen that when the pressure drop instability occurs, the amplitude and period of G and ΔP fluctuations over time are large, and the curves of G and ΔP show a phase difference of 180°; when the density wave instability occurs, the amplitude and period of G and ΔP fluctuations over time are small, and the curves of G and ΔP show a phase difference of less than 90°; the steps for calculating the period t of density wave instability are as follows:

[0055] First, calculate the average flow rate of the refrigerant when it flows into the inlet of the experimental section: According to the temperature value T measured by the thermocouple at the inlet of the experimental section in , combined with REFPROP 9.0 of NIST software, the density of the refrigerant at the inlet of the experimental section can be calculated in , the average flow rate of the refrigerant when it flows into the inlet of the experimental section can be expressed as:

[0056]

[0057] In the formula, v in is the average flow velocity of the refrigerant when it flows into the inlet of the experimental section, in m / s; ρ in is the density of the refrigerant at the inlet of the experimental section, in kg / m 3 ;

[0058] Secondly, since the refrigerant will undergo phase change in the experimental section, the amount of gas phase in the experimental section will increase, which will increase the average flow rate of the fluid in the experimental section. The average flow rate in the experimental section can generally be expressed as:

[0059] v=1.5vin (7)

[0060] Where v is the average flow velocity in the experimental section, in m / s;

[0061] Then, calculate the time t required for the refrigerant to flow through the experimental section test , whose expression is:

[0062]

[0063] Where, L is the length of the experimental section, in meters; t test It is the time required for the fluid to flow through the experimental section, in seconds.

[0064] The period t of density wave instability is the time t required for the refrigerant to flow through the experimental section test 1.5 times, that is:

[0065] t=1.5t test (9)

[0066] To sum up, first of all, Figure 5a and Figure 5b The transient mass flow rate G is related to Figure 3 Time-averaged mass flow rate in the pressure drop-mass flow rate characteristic curve of the experimental section Correspond respectively and determine Figure 5a and Figure 5b The position of the pressure drop-mass flow rate characteristic curve of the experimental section where the transient mass flow rate G is located can be used to preliminarily determine the type of instability. Figure 4a and Figure 5a Medium parameter (P test , T out , G, ΔP) fluctuation characteristics over time, and combined observation Figure 4b and Figure 5b Medium parameter (P test , T out , G, ΔP) fluctuation characteristics over time: when pressure drop instability occurs, the amplitude and period of G and ΔP fluctuation over time are large, and the curves of G and ΔP show a phase difference of 180°; when density wave instability occurs, the amplitude and period of G and ΔP fluctuation over time are small, and the curves of G and ΔP show a phase difference of less than 90°; finally, the final instability type is determined according to the calculation method of the period t of density wave instability.

[0067] The present invention has many specific application paths. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements can be made without departing from the principle of the present invention. These improvements should also be regarded as the protection scope of the present invention.

Claims

1. A flow instability measurement system, characterized in that: include: Refrigerant liquid storage tank (1), semiconductor refrigeration plate (2), heating plate (3), supercooler (4), micro magnetic drive pump (5), first pressure sensor (6), first differential pressure sensor (7), buffer (8), second pressure sensor (9), filter (10), volume flow meter (11), second differential pressure sensor (12), preheating section inlet pressure sensor (13), preheating section inlet thermocouple (14), preheating section (15), preheating section DC power supply (16), preheating section differential pressure sensor (17), experimental section inlet thermocouple (18), smooth copper tube (19), experimental section (20), experimental section DC power supply (21 ), experimental section thermocouple (22), experimental section outlet thermocouple (23), experimental section differential pressure sensor (24), experimental section outlet pressure sensor (25), condenser (26), water tank (27), large flow gear pump (28), transparent polytetrafluoroethylene tube (29) and water pipe (30); the semiconductor refrigeration plate (2) and heating plate (3) are respectively fixed on the top and bottom of the refrigerant storage tank (1); the refrigerant storage tank (1), supercooler (4), micro magnetic drive pump (5), buffer (8), filter (10), volume flow meter (11), preheating section (15), smooth copper tube (19), experimental section (20), light The smooth copper tube (19) and the condenser (26) are connected in sequence via a transparent polytetrafluoroethylene tube (29); the first pressure sensor (6) and the first differential pressure sensor (7) and the micro magnetic drive pump (5), the second pressure sensor (9) and the buffer (8), the second differential pressure sensor (12) and the volume flow meter (11), the preheating section inlet pressure sensor (13) and the preheating section differential pressure sensor (17) and the preheating section (15), and the experimental section differential pressure sensor (24) and the experimental section outlet pressure sensor (25) and the experimental section (20) are all connected via a transparent polytetrafluoroethylene tube (29); the preheating section DC power supply ( 16) The positive and negative electrodes are connected to the wires wound around the two ends of the preheating section (15) through terminals, and the positive and negative electrodes of the DC power supply (21) of the experimental section are connected to the wires wound around the two ends of the experimental section (20) through terminals; the pins of the thermocouple (18) at the inlet of the experimental section and the thermocouple (23) at the outlet of the experimental section are connected to the outer wall of the smooth copper tube (19), and the pins of the thermocouple (14) at the inlet of the preheating section are connected to the preheating section (15); the pins of the thermocouple (22) of the experimental section are filled and bonded to the grooves opened on the tube wall of the experimental section (20); the subcooler (4), condenser (26), water tank (27) and large-flow gear pump (28) are connected in sequence through a water pipe (30).

2. The flow instability measurement system according to claim 1, characterized in that: The semiconductor cooling plate (2) and the heating plate (3) are fixed to the refrigerant liquid storage tank (1) by means of a cable tie.

3. The flow instability measurement system according to claim 1, characterized in that: The pins of the experimental section inlet thermocouple (18) and the experimental section outlet thermocouple (23) are bonded to the outer wall of the smooth copper tube (19) by means of thermal insulation tape.

4. The flow instability measurement system according to claim 1, characterized in that: The pins of the preheating section inlet thermocouple (14) are bonded to the preheating section (15) by means of a heat insulating tape.

5. The flow instability measurement system according to claim 1, characterized in that: The preheating section (15) and the experimental section (20) are manufactured in the same manner, with a copper tube (201) serving as a substrate, and a first insulating tape (202), a resistance wire (203), a second insulating tape (204), a heat insulating tape (205) and heat preservation cotton (206) being uniformly wound around the copper tube (201) in sequence from the inside to the outside.

6. The flow instability measurement system according to claim 1, characterized in that: The refrigerant liquid storage tank (1), the subcooler (4), the micro magnetic drive pump (5), the buffer (8), the filter (10), the volume flow meter (11), the preheating section (15), the smooth copper tube (19), the experimental section (20) and the condenser (26) in the system constitute a refrigerant circulation system; the subcooler (4), the condenser (26), the water tank (27) and the large-flow gear pump (28) constitute a cooling water circulation system; the refrigerant and cooling water flowing through the subcooler (4) are in a countercurrent form.

7. The flow instability measurement system according to claim 1, characterized in that: The maximum flow rate of the micro magnetic drive pump (5) is 2.4 L / min; the maximum flow rate of the large flow gear pump (28) is 40 L / min.

8. A method for identifying instability types of a flow instability measurement system, based on the system according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) Given system pressure P s-out , heating power q of the experimental section, subcooling degree ΔT at the entrance of the experimental section in , by reducing the time-averaged volume flow in the system To preset values ​​v1, v2…v n , using the recorded transient volume flow q v Calculate the corresponding time-averaged mass flow rate Simultaneously monitor the time-averaged pressure drop within the test section Draw the pressure drop-mass flow rate characteristic curve corresponding to the experimental section under the time average value; 2) Collect the transient value P of the current test section outlet pressure of the system out And the transient pressure drop ΔP in the experimental section, and calculate the transient saturation pressure P in the experimental section sat , combined with the transient saturation pressure P sat The time-averaged saturation pressure in the experimental section is calculated Acquisition system current test section outlet thermocouple transient temperature T out ; 3) Preliminarily determine the average mass flow rate at different times through the experimental section pressure drop-mass flow rate characteristic curve drawn in step 1) The corresponding instability type; using the current transient pressure P of the test section outlet of the system collected in step 2) out and the transient saturation pressure P in the experimental section sat , combined with the time-averaged saturation pressure in the experimental section calculated in step 2) The transient pressure amplitude ratio P of the experimental section is calculated. test Combined with the transient pressure drop ΔP in the experimental section collected in step 2) and the transient temperature T of the thermocouple at the outlet of the current experimental section of the system out , draw the curves of the transient pressure amplitude ratio of the experimental section and the transient temperature of the thermocouple at the outlet of the experimental section changing with time, and the curves of the transient mass flow rate of the experimental section and the transient pressure drop of the experimental section changing with time; 4) According to the fluctuation amplitude and period of each parameter over time in the curve diagram of step 3), the type of instability generated in the system is further identified; according to the calculated period t of density wave instability, the type of instability generated in the system is finally identified.

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