CN112218497A - Two-phase heat dissipation loop active control system and method - Google Patents
Two-phase heat dissipation loop active control system and method Download PDFInfo
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- CN112218497A CN112218497A CN202011079353.7A CN202011079353A CN112218497A CN 112218497 A CN112218497 A CN 112218497A CN 202011079353 A CN202011079353 A CN 202011079353A CN 112218497 A CN112218497 A CN 112218497A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2029—Modifications to facilitate cooling, ventilating, or heating using a liquid coolant with phase change in electronic enclosures
- H05K7/20336—Heat pipes, e.g. wicks or capillary pumps
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2029—Modifications to facilitate cooling, ventilating, or heating using a liquid coolant with phase change in electronic enclosures
- H05K7/20309—Evaporators
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2029—Modifications to facilitate cooling, ventilating, or heating using a liquid coolant with phase change in electronic enclosures
- H05K7/20318—Condensers
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2029—Modifications to facilitate cooling, ventilating, or heating using a liquid coolant with phase change in electronic enclosures
- H05K7/20381—Thermal management, e.g. evaporation control
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Abstract
A two-phase heat dissipation loop active control system and a method thereof comprise an evaporator, wherein the evaporator comprises a capillary core, a compensation cavity is arranged above the capillary core, a steam channel is arranged on the bottom surface of the capillary core and is directly connected with a heating chip, the steam channel is connected with a steam pipeline, the steam pipeline is connected with an inlet of a condenser, the condenser and a micropump are connected with the compensation cavity, a first electromagnetic valve is arranged between the micropump and the compensation cavity, the compensation cavity is connected with an inlet of the micropump, and a second electromagnetic valve is arranged between the compensation cavity and a main liquid reservoir; a first temperature sensor and a second temperature sensor are arranged on the exposed surface of the chip; a first pressure sensor is arranged in the compensation cavity, and a second pressure sensor is arranged at the outlet of the steam channel; the sensor and the electromagnetic valve are both connected with the PI control system. The PI control system judges the boiling mode of the evaporator according to the feedback pressure and temperature signals, forms a pulse electric signal to control the opening of the two electromagnetic valves, and enables the evaporation chamber to be in a high-efficiency film evaporation state.
Description
Technical Field
The invention belongs to the field related to ultrahigh heat flow density heat dissipation, and particularly relates to a two-phase heat dissipation loop active control system and method, which can be used in the fields of cooling and heat dissipation of electronic components and the like.
Background
In future space-based applications, the power consumption of electronic components is increasing, resulting in an increasing demand for efficient compact heat dissipation systems. In the past, two-phase heat transfer devices driven by capillary forces, such as Capillary Pumped Loops (CPL) and Loop Heat Pipes (LHP), have met the thermal requirements of these systems. However, these devices may not be able to meet the stringent demands of future space missions, and the cooling requirements of emerging high power applications (e.g., laser weapons, high integration radar, and large multi-mission spacecraft) are expected to exceed the heat transfer capabilities of passive capillary-driven two-phase heat transfer devices (e.g., loop heat pipes). In ground application, the monolithic integration degree and frequency of a digital chip, a power device and the like are continuously improved, the heat flux density is rapidly increased, and the demand on an efficient cooling technology is urgent; applications are arrayed and scaled (such as data centers, phased arrays, multi-processor workstations and the like), and higher requirements are placed on the stability and reliability of a heat dissipation system. In response to the ever-increasing cooling demand, a pump-capillary force hybrid driven two-phase loop (HTPL) has been developed, which has an expandable design of a flat plate evaporator and an innovative combination of micro-pump (active) and capillary force (passive), and can effectively overcome the limitations of a passive capillary system, enhance the system operation stability and further improve the heat exchange capacity at high heat flux density.
However, HTPL also suffers from the following inherent problems: (1) temperature overshoot at HTPL cold start, which can cause thermal stress, can, in extreme cases, exceed the maximum operating temperature of the electronic package. The temperature overshoot that occurs during cold start-up is due to the continuous flooding in the evaporator and the increase in steam pressure (steam temperature) required to evacuate the steam from the steam chamber and steam line; (2) the HTPL dynamic operation has poor regulation and control capability, when the heat input in the evaporator is changed, the liquid supply in the evaporator is completely automatically regulated by virtue of capillary force, the regulation range is very limited, and under the condition of lower heat flow density, meniscus in a capillary core structure can be partially disappeared to cause working medium overflow, so that the bottom plate of the evaporator generates large temperature fluctuation, and under the condition of higher heat flow density, the evaporator can be burnt to dry due to the limitation of capillary force. The above two problems limit the practical application of HTPL to some extent.
Disclosure of Invention
Aiming at the problems in the prior art, the working characteristics of HTPL are combined, and a two-phase heat dissipation loop active control system and method are provided. An electromagnetic valve is added in the heat dissipation loop to control the pressure of liquid in the cold starting process, so that the thermal resistance in low heat input is reduced, and the inherent cold starting problem of HTPL is improved; meanwhile, the pressure of liquid in the compensation cavity can be controlled by using an electromagnetic valve, so that a phase change mode in the capillary core is controlled, efficient film evaporation is formed, the phenomena of continuous overflow of an evaporator and dry burning of the evaporator are avoided, and the stability of the HTPL dynamic operation process is improved.
In order to achieve the purpose, the invention adopts the technical scheme that:
a two-phase heat dissipation loop active control system comprises a pump-capillary force hybrid driven two-phase heat dissipation loop and a PI control system which are connected, wherein the pump-capillary force hybrid driven two-phase heat dissipation loop comprises an evaporator, a compensation cavity, a capillary core, a condenser, an auxiliary liquid storage device, a main liquid storage device and a micropump;
the evaporator comprises a capillary core, a compensation cavity is arranged above the capillary core, a steam channel is formed in the bottom surface of the capillary core and is connected with an inlet of a steam pipeline, an outlet of the steam pipeline is connected with an inlet of a condenser, an outlet of the condenser is connected with an inlet of the compensation cavity through an auxiliary liquid storage device and a micropump, a first electromagnetic valve is arranged between the micropump and the compensation cavity, the compensation cavity is connected with an inlet of the micropump through a main liquid storage device, and a second electromagnetic valve is arranged between the compensation cavity and the main liquid storage device;
a first temperature sensor and a second temperature sensor are arranged on the exposed surface of the chip;
a first pressure sensor is arranged in the compensation cavity, and a second pressure sensor is arranged at the outlet of the steam channel;
and the first pressure sensor, the second pressure sensor, the first temperature sensor, the second temperature sensor, the first electromagnetic valve and the second electromagnetic valve are all connected with the PI control system.
The invention has the further improvement that the liquid working medium is heated in the capillary core to become steam, then enters the steam channel, enters the condenser through the steam pipeline, releases latent heat to become supercooled liquid, enters the auxiliary liquid storage device, enters the compensation cavity through the second liquid pipeline under the suction of the micropump, part of the liquid is sucked to the exposed surface of the chip by the capillary core to carry out phase change heat exchange, and the rest of the liquid flows through the first liquid pipeline to enter the main liquid storage device, thereby completing the working medium circulation.
The further improvement of the invention is that the PI control system receives signals from the first temperature sensor, the second temperature sensor, the first pressure sensor and the second pressure sensor, outputs pulse electrical signals after operation, controls the opening degree of the first electromagnetic valve and the second electromagnetic valve and further adjusts the pressure of liquid in the compensation cavity.
The invention is further improved in that a first pressure sensor is used for collecting a pressure signal in the compensation cavity, a second pressure sensor is used for collecting a pressure signal at the steam outlet of the evaporator, then the pressure signal and the pressure signal are transmitted to a PI control system, and the PI control system outputs pulse electric signals to the first electromagnetic valve and the second electromagnetic valve after operation and controls the opening of the first electromagnetic valve and the second electromagnetic valve.
The invention is further improved in that the condenser is a double-pipe condenser or an external fin condenser.
A further improvement of the invention is that the bottom of the capillary wick is in contact with the exposed face of the chip.
A two-phase heat dissipation loop active control method comprises the steps that a first pressure sensor collects pressure signals in a compensation cavity, a second pressure sensor collects pressure signals at a steam outlet of an evaporator, then the pressure signals and the pressure signals are transmitted to a PI control system, the PI control system outputs pulse electric signals to a first electromagnetic valve and a second electromagnetic valve after operation, and the opening degree of the first electromagnetic valve and the opening degree of the second electromagnetic valve are controlled;
the temperature information of the exposed surface of the chip, acquired by the first temperature sensor and the second temperature sensor, is transmitted to a PI control system, the PI control system carries out real-time processing by adopting a moving average algorithm to obtain an average value, whether thin film evaporation is formed at the bottom of the capillary core is judged according to the average value, if the thin film evaporation is formed, the PI control system does not send a pulse signal, if the thin film evaporation is not formed, the PI control system outputs the pulse signal and controls the first electromagnetic valve and the second electromagnetic valve until the thin film evaporation is formed at the bottom of the capillary core.
The invention is further improved in that the film formation is evaporated when the following two conditions are satisfied: the vapor pressure calculated according to the second pressure sensor exceeds the pressure of the liquid in the compensation cavity; the average temperature value of 20-30 data points acquired by the first temperature sensor is used as a reference, the moving average value of the temperature acquired by the first temperature sensor on the surface of the exposed surface of the chip is reduced by 5%, and meanwhile, the average temperature value of 20-30 data points acquired by the second temperature sensor is used as a reference, and the moving average value of the temperature acquired by the second temperature sensor on the surface of the exposed surface of the chip is reduced by 5%.
The invention is further improved in that the collection frequency of the first pressure sensor and the second pressure sensor is 50-100 data points per second, and the collection frequency of the first temperature sensor and the second temperature sensor is 1-3 data points per second.
Compared with the prior art, the invention mainly has the following beneficial effects:
according to the invention, a first electromagnetic valve is arranged between a micro pump and a compensation cavity, the compensation cavity is connected with an inlet of the micro pump through a main liquid storage device, and a second electromagnetic valve is arranged between the compensation cavity and the main liquid storage device; a first temperature sensor and a second temperature sensor are arranged on the exposed surface of the chip; a first pressure sensor is arranged in the compensation cavity, and a second pressure sensor is arranged at the outlet of the steam channel; and the first pressure sensor, the second pressure sensor, the first temperature sensor, the second temperature sensor, the first electromagnetic valve and the second electromagnetic valve are all connected with the PI control system. The automatic control of the first electromagnetic valve and the second electromagnetic valve can be realized through temperature and pressure signals, and the stability of the HTPL in the dynamic operation process is improved. According to the invention, the capillary core is arranged, so that the vapor and the liquid can be isolated by the capillary core, the separation of a vapor pipeline and a liquid pipeline is realized, and the problems of pressure and temperature fluctuation of vapor-liquid two-phase flow are solved.
The PI control system judges the boiling mode of the evaporator according to the feedback pressure and temperature signals, forms a pulse electric signal to control the opening of the two electromagnetic valves, and enables the evaporation chamber to be in a high-efficiency film evaporation state. When a small amount of heat is applied to the system, by adjusting the opening of the first solenoid valve and the second solenoid valve until the heat is added to the evaporator 8 and the evaporation of the thin film occurs, a stable meniscus is formed in the capillary wick when the evaporation of the thin film occurs in the capillary wick, and the opening of the first solenoid valve and the second solenoid valve will be determined by the output signal of the controller: when the heat input of the evaporator is increased or reduced, the pressure at the outlet of the evaporator is changed at the moment, the second pressure sensor transmits pressure information to the control system, and after the pressure information is compared and calculated with the pressure in the compensation cavity transmitted by the first pressure sensor, control signals are transmitted to the first electromagnetic valve and the second electromagnetic valve, the opening degree of the first electromagnetic valve and the second electromagnetic valve is adjusted, so that the pressure in the compensation cavity is increased or reduced, the bottom of the capillary core is kept in efficient thin film evaporation, and the temperature of the chip is remarkably reduced. When the input heat is very high, the PI control system actively controls the opening degrees of the first electromagnetic valve and the second electromagnetic valve, so that the pressure head provided by the micro pump can be fully utilized, the pressure head provided by the micro pump is concentrated in the compensation cavity, and the steam is prevented from entering the compensation cavity through the capillary core, thereby avoiding the phenomenon that the evaporator is burnt dry, and improving the heat exchange capacity of the loop under high heat flow density.
Furthermore, the capillary core is directly attached to the exposed surface of the chip, and the fluid is directly contacted with the heat source, so that the thermal interface material and the thermal resistance of the intermediate transition layer in the traditional heat dissipation means are removed, and lower overall thermal resistance and more efficient heat dissipation can be realized.
Drawings
Fig. 1 is a schematic structural diagram of an active control system of a two-phase heat dissipation loop driven by a pump-capillary force hybrid according to the present invention.
Fig. 2 is a schematic diagram of the control process of the present invention.
Wherein: 1 is a first electromagnetic valve; 2 is a first pressure sensor; a second electromagnetic valve 3; 4 is a first temperature sensor; 5 is a second temperature sensor; 6 is a second pressure sensor; 7 is a PI control system; 8 is an evaporator; 9 is a compensation cavity; 10 is a capillary core; 10-1 is a steam channel; 11 is a sealing gasket; 12 is the exposed surface of the chip; 13 is a gas pipeline; 14 is a first liquid pipeline; 15 is a condenser; 16 is a secondary reservoir; 17 is a main liquid storage device; 18 is a micro pump; 19 is a second liquid line; and 20, a fastening bolt.
Detailed Description
The invention will be further described with reference to the accompanying drawings.
The pump-capillary force hybrid driving two-phase loop heat dissipation device in the prior art needs to be further modified to meet the requirements of practical application. To start the circuit and prevent the evaporator from overflowing continuously, the pressure in the vapor chamber must be greater than the pressure in the liquid chamber, while the vapor pressure must be high enough to expel most of the liquid in the vapor line; in order to improve the stability in the dynamic operation process, the pressure of the evaporator compensation cavity and the evaporation chamber must be effectively controlled, so that the phase change mode in the capillary core is controlled, the bottom of the capillary core keeps efficient thin film evaporation heat exchange, and the phenomena of large temperature fluctuation and evaporator dry burning are avoided.
By using an active control strategy, the thermal resistance in the HTPL cold start process can be reduced when low heat is input, the inherent cold start problem of the HTPL is improved, and meanwhile, the pressure in the compensation cavity can be effectively controlled, so that the bottom of the capillary core can keep efficient thin film evaporation heat exchange, the phenomena of continuous overflow of the evaporator and dry burning of the evaporator are avoided, and the stability of the HTPL during dynamic operation is improved.
According to the invention, a plurality of temperature measuring points and pressure measuring points are added in the mixed two-phase heat exchange loop, and the opening of a plurality of electromagnetic valves is controlled by using the PI control system, so that the pressure of liquid in a compensation cavity is effectively controlled, the inherent cold start problem of an HTPL (pump-capillary force mixed driving two-phase loop) is improved, the phase change mode in a capillary core can be controlled, efficient thin film evaporation is formed, and the stability, the heat exchange capability and the limit heat flux density in the dynamic operation process of the HTPL are improved.
Referring to fig. 1, the active control system of the pump-capillary force hybrid driven two-phase heat dissipation loop of the present invention includes a pump-capillary force hybrid driven two-phase heat dissipation loop and an active control system connected to each other, where the pump-capillary force hybrid driven two-phase heat dissipation loop includes an evaporator 8, a compensation chamber 9, a capillary wick 10, a vapor channel 10-1, a sealing gasket 11, a chip exposed surface 12, a vapor pipeline 13, a first liquid pipeline 14, a condenser 15, an auxiliary reservoir 16, a main reservoir 17, a micro pump 18, a second liquid pipeline 19, and a fastening bolt 20. The active control system comprises a first temperature sensor 4, a second temperature sensor 5, a first pressure sensor 2, a second pressure sensor 6, a PI control system 7, a first solenoid valve 1 and a second solenoid valve 3.
The evaporator 8 is connected with the chip exposed surface 12 through a fastening bolt 20, and a sealing gasket is arranged around the evaporator to prevent working media from flowing out to damage a circuit. The upper part of the capillary core 10 is provided with a compensation cavity 9, the bottom surface of the capillary core 10 is provided with a plurality of steam channels 10-1 which are arranged in parallel, the steam channels 10-1 are connected with an inlet of a steam pipeline 13, an outlet of the steam pipeline 13 is connected with an inlet of a condenser 15, an outlet of the condenser 15 is connected with an inlet of a micro pump 18 through an auxiliary liquid storage device 16, an outlet of the micro pump 18 is connected with an inlet of the compensation cavity 9 through a second liquid pipeline 19, the second liquid pipeline 19 is provided with a first electromagnetic valve 1, an outlet of the compensation cavity 9 is connected with an inlet 17 of a main liquid storage device through a first liquid pipeline 14, the first liquid pipeline 14 is provided with a second electromagnetic valve 3, and an outlet of the main liquid storage device 17 is connected.
Referring to fig. 1, a liquid working medium is heated in a capillary core 10 to become steam, and sequentially enters a plurality of steam channels 10-1 and steam pipelines 13 which are arranged in parallel and have the width and height of 1-3 mm, latent heat is released in a condenser 15 to become supercooled liquid, the supercooled liquid enters an auxiliary liquid storage device 16, the supercooled liquid enters a compensation cavity 9 through a second liquid pipeline 19 under the suction of a micro pump 18, part of the liquid is sucked to a chip exposed surface 12 by the capillary core 10 to perform phase change heat exchange, and the rest of the liquid flows through a first liquid pipeline 14 to enter a main liquid storage device 17, so that working medium circulation is completed.
The active control system plays an important role throughout the cycle. The first electromagnetic valve 1 and the second electromagnetic valve 3 are used for regulating and controlling the liquid pressure in the compensation cavity 9; the first liquid pipeline 14 and the second liquid pipeline 19 are respectively provided with an electromagnetic valve, so that a pressure head provided by the micropump 18 can be fully utilized, the pressure adjusting range in the compensation cavity 9 is enlarged to the maximum extent, and the first temperature sensor 4 and the second temperature sensor 5 are arranged at different positions on the exposed surface 12 of the chip and are used for obtaining the temperature of the exposed surface 12 of the chip; the first pressure sensor 2 is arranged in the compensation cavity 9 and used for monitoring the pressure of liquid in the compensation cavity 9; a second pressure sensor 6 is arranged at a steam outlet of the evaporator 8 and used for monitoring steam pressure; the first pressure sensor 2, the second pressure sensor 6, the first temperature sensor 4, the second temperature sensor 5, the first electromagnetic valve 1 and the second electromagnetic valve 3 are all connected with a PI control system 7. The PI control system 7 is independently arranged, takes the pressure of liquid in the compensation cavity 9 and the pressure at the steam outlet of the evaporator as control variables of the control system, receives signals from the first temperature sensor 4, the second temperature sensor 5, the first pressure sensor 2 and the second pressure sensor 6, outputs pulse electric signals after operation, controls the opening degrees of the first electromagnetic valve 1 and the second electromagnetic valve 3, and further adjusts the pressure of the liquid in the compensation cavity 9.
The capillary core isolates the vapor from the liquid, thereby realizing the separation of the vapor pipeline and the liquid pipeline and solving the problems of pressure and temperature fluctuation of vapor-liquid two-phase flow.
The capillary core 10 is directly attached to the exposed surface 12 of the electronic chip for packaging and heat dissipation, so that interface thermal resistance and transition layer thermal resistance formed by indirect attachment are eliminated.
The condenser 15 may be a double pipe condenser cooled by liquid, or an external fin condenser cooled by a fan.
The vapor pipeline 13 is connected with a condenser 15, and after the condensate is injected into an auxiliary liquid storage device 16, the condensate is pumped out by a micro pump 18 and enters the compensation cavity 9; the second liquid line 19 is connected to the main reservoir 17, the micro pump 18 and the compensation chamber 9, respectively, to form a liquid circuit.
Referring to fig. 2, the control process method of the present invention is: the first pressure sensor 2 collects a pressure signal P1 in the compensation chamber 9, the second pressure sensor 6 collects a pressure signal P2 at the steam outlet of the evaporator 8, and the collection frequency of the first pressure sensor 2 and the second pressure sensor 6 is 50-100 data points per second. The pressure signal P1 and the pressure signal P2 are transmitted to the PI control system 7, and the PI control system 7 performs calculation, outputs pulse electric signals to the first solenoid valve 1 and the second solenoid valve 3, and controls the opening degrees thereof.
The acquisition frequency of the first temperature sensor 4 and the second temperature sensor 5 is 1-3 data points per second, the first temperature sensor 4 and the second temperature sensor 5 acquire the temperature information of the exposed surface 12 of the chip and transmit the temperature information to the PI control system 7, the PI control system 7 adopts a moving average algorithm to perform real-time processing, and the temperature average value of 20-30 data points acquired by the first temperature sensor 4 is used as a reference, so that the requirement of meeting the requirement of the real-time processing of the PI control system 7 is met
(
I is a temperature average value, i is a certain moment, i +1 is the next moment), that is, the moving average value of the temperature collected by the first temperature sensor 4 on the surface of the chip exposed surface 12 is reduced by 5%, and meanwhile, the moving average value of the temperature collected by the second temperature sensor 5 on the surface of the chip exposed surface 12 is reduced by 5% by taking the temperature average value of 20-30 data points collected by the second temperature sensor 5 as a reference, so that thin film evaporation is formed, and no pulse signal is sent out for monitoring the temperature change of the chip exposed surface 12 and judging whether the thin film evaporation is formed. If the thin film evaporation is formed, the opening degree of the first solenoid valve 1 and the second solenoid valve 3 is maintained, if the thin film evaporation is not formed, a pulse signal is output, and the first solenoid valve 1 and the second solenoid valve 3 are controlled until the thin film evaporation is formed.
The PI control system 7 adopts PI algorithm to operate, P control is a main control function, I control plays an auxiliary role in eliminating residual deviation, and a dynamic equation is as follows:
wherein u (t) is the output, t is the time, KpProportional gain, e (T) input quantity, TiFor the integration time constant, e (τ) is the input quantity and τ is the integration time.
Proportional gain K of dynamic equationpIntegral time τ and integral time constant TiAccording to the actual systemThe operation is selected and optimized, and the system is ensured to have better robustness and accuracy.
During the dynamic operation of the system, the operating judgment conditions of the PI control system 7 are as follows: depending on whether the difference between the steam pressure P2 measured by the second pressure sensor 6 and the compensation chamber pressure P1 measured by the first pressure sensor 2 exceeds the set point SP, if so, operation is performed, and if not, no operation is performed.
The opening of the electromagnetic valve is adjusted by adopting equal percentage characteristics, so that the adjustment is stable and the adjustment performance is good.
The PI control system 7 judges the boiling mode of the evaporator 8 according to the feedback pressure and temperature signals, forms a pulse electric signal to control the opening degree of the two electromagnetic valves, and enables the evaporation chamber 8 to be in a high-efficiency film evaporation state.
Specifically, the control method of the present invention is as follows:
when no heat is applied to the system, the micro-pump 18 over-supplies liquid to the chip exposed face 12 through the capillary wick, resulting in the vapor channel 10-1 being filled with liquid. As heat is applied to the system, the liquid will be heated up until pool boiling begins and vapour is generated due to the presence of excess liquid, as more heat is applied more vapour is generated and the vapour pressure P2 continues to increase until the vapour pressure P2 exceeds the liquid pressure P1 in the compensation chamber 9 at which time a stable meniscus forms. However, the vapor pressure required to evacuate the liquid in the vapor line 13 may exceed the maximum capillary force, at which point the vapor will enter the compensation chamber 9 through the capillary wick 10 causing destabilization of the HTPL (pump-capillary force hybrid driven two-phase circuit), so at start-up the liquid pressure P1 in the compensation chamber 9 should be minimized to avoid continuous overflow of the vapor chamber, but high enough so that the vapor does not damage the meniscus entering the compensation chamber 9.
When no heat is applied to the system, the first electromagnetic valve 1 keeps a smaller opening degree, the second electromagnetic valve 3 keeps a maximum opening degree, the pressure in the compensation cavity is the lowest state that the system can be started smoothly, and the opening degree percentages of the first electromagnetic valve 1 and the second electromagnetic valve 3 are optimized according to the pressure head of the used micro pump, the diameter of a pipeline and the structure of an evaporator.
When a small amount of heat is applied to the system, the first solenoid valve 1 and the second solenoid valve 3 will maintain this state, i.e., the first solenoid valve 1 maintains a small opening degree, and the second solenoid valve 3 maintains a maximum opening degree until the heat is added to the evaporator 8, where thin film evaporation occurs when the following two conditions are satisfied: 1) the vapour pressure calculated from the second pressure sensor 6 exceeds the pressure of the liquid in the compensation chamber 9 (the pressure in the compensation chamber 9 is obtained by the first pressure sensor 2); 2) the average temperature values of 20 to 30 data points acquired by the first temperature sensor 4 are used as a reference, the moving average value of the temperature acquired by the first temperature sensor 4 on the surface of the chip exposed surface 12 is reduced by 5%, and meanwhile, the moving average value of the temperature acquired by the second temperature sensor 5 on the surface of the chip exposed surface 12 is reduced by 5% (the temperature of the chip exposed surface 12 is obtained by the first temperature sensor 4 and the second temperature sensor 5) by using the average temperature values of 20 to 30 data points acquired by the second temperature sensor 5 as a reference.
When the evaporation of the film occurs in the capillary core, a stable meniscus is formed in the capillary core, and the opening degrees of the first solenoid valve 1 and the second solenoid valve 3 are determined by the output signals of the PI controller 7: when the heat input of the evaporator is increased or reduced, the outlet pressure P2 of the evaporator is changed at this time, the second pressure sensor 6 transmits pressure information to the PI control system 7, and after comparing the pressure information with the pressure P1 in the compensation chamber transmitted by the first pressure sensor 2, transmits a control signal to the first electromagnetic valve 1 and the second electromagnetic valve 3, and adjusts the opening degree of the first electromagnetic valve and the second electromagnetic valve, so that the pressure in the compensation chamber 9 is increased or reduced, and then the bottom of the capillary core is kept in efficient thin film evaporation, and the influence of temperature fluctuation is reduced.
When the input heat is very high, the PI control system 7 actively controls the first electromagnetic valve 1 to keep 100% of opening degree, the second electromagnetic valve 3 keeps smaller opening degree, the pressure head provided by the micro pump 18 can be fully utilized at the moment, the pressure head provided by the micro pump 18 is concentrated in the compensation cavity 9, steam is prevented from entering the compensation cavity 9 through a capillary core, the phenomenon that the evaporator 8 is burnt to be dry is avoided, the heat exchange capacity of the loop under high heat flow density is improved, and the opening degree percentage of the second electromagnetic valve 3 needs to be optimized according to the pressure head of the used micro pump, the evaporator structure and the input heat.
The heat dissipation principle of the invention is as follows:
for a pump-capillary force hybrid driven two-phase loop, the duty cycle is: supercooled liquid in the auxiliary liquid reservoir 16 and the main liquid reservoir 17 is conveyed to a compensation cavity 9 in the evaporator 8 by a micro pump 18, only a small part of liquid in the compensation cavity 9 is sucked in through a capillary wick, and the rest of liquid returns to the main liquid reservoir 17 through a first liquid pipeline 14; the liquid pumped by the capillary force from the compensation cavity 9 is evaporated at the bottom of the capillary core, the formed steam enters the condenser 15 through the steam channel 10-1 and the steam pipeline 13, and the steam is collected after being condensed and enters the secondary liquid reservoir 16 for circulation.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. The active control system of the two-phase heat dissipation loop is characterized by comprising the two-phase heat dissipation loop and a PI control system (7) which are driven by a pump-capillary force hybrid drive, wherein the two-phase heat dissipation loop driven by the pump-capillary force hybrid drive comprises an evaporator (8), a compensation cavity (9), a capillary core (10), a condenser (15), an auxiliary liquid storage device (16), a main liquid storage device (17) and a micro pump (18);
the evaporator (8) comprises a capillary core (10), a compensation cavity (9) is arranged above the capillary core (10), a steam channel (10-1) is formed in the bottom surface of the capillary core (10), the steam channel (10-1) is connected with an inlet of a steam pipeline (13), an outlet of the steam pipeline (13) is connected with an inlet of a condenser (15), an outlet of the condenser (15) is connected with an inlet of the compensation cavity (9) through an auxiliary liquid storage device (16) and a micro pump (18), a first electromagnetic valve (1) is arranged between the micro pump (18) and the compensation cavity (9), the compensation cavity (9) is connected with an inlet of the micro pump (18) through a main liquid storage device (17), and a second electromagnetic valve (3) is arranged between the compensation cavity (9) and the main liquid storage device (17);
a first temperature sensor (4) and a second temperature sensor (5) are arranged on the exposed surface (12) of the chip;
a first pressure sensor (2) is arranged in the compensation cavity (9), and a second pressure sensor (6) is arranged at the outlet of the steam channel (10-1);
the first pressure sensor (2), the second pressure sensor (6), the first temperature sensor (4), the second temperature sensor (5), the first electromagnetic valve (1) and the second electromagnetic valve (3) are all connected with the PI control system (7).
2. The active control system of the two-phase heat dissipation loop of claim 1, wherein the liquid working medium is heated in the capillary core (10) to become steam, and then enters the steam channel (10-1), and enters the condenser (15) through the steam pipeline (13), releases latent heat to become supercooled liquid, and enters the secondary reservoir (16), and enters the compensation chamber (9) through the second liquid pipeline (19) under the suction of the micro pump (18), part of the liquid is sucked to the chip exposed surface (12) by the capillary core (10) to perform phase change heat exchange, and the rest of the liquid flows through the first liquid pipeline (14) to enter the primary reservoir (17), thereby completing the working medium circulation.
3. The active control system of the two-phase heat dissipation loop according to claim 1, wherein the PI control system (7) receives signals from the first temperature sensor (4), the second temperature sensor (5), the first pressure sensor (2) and the second pressure sensor (6), outputs a pulse electrical signal after operation, and controls the opening degrees of the first solenoid valve (1) and the second solenoid valve (3), thereby adjusting the pressure of the liquid in the compensation chamber (9).
4. The active control system of the two-phase heat dissipation loop of claim 1, wherein a pressure signal (P1) in the compensation chamber (9) is collected by the first pressure sensor (2), a pressure signal (P2) at a steam outlet of the evaporator (8) is collected by the second pressure sensor (6), the pressure signal (P1) and the pressure signal (P2) are transmitted to the PI control system (7), and the PI control system (7) outputs pulse electric signals to the first solenoid valve (1) and the second solenoid valve (3) after operation and controls the opening degrees of the first solenoid valve (1) and the second solenoid valve (3).
5. The active control system for a two-phase heat dissipation loop of claim 1, wherein the condenser is a tube-in-tube condenser or an external fin condenser.
6. The active control system of two-phase heat dissipation loop of claim 1, wherein the bottom of the capillary wick (10) is in contact with the exposed surface (12) of the chip.
7. The two-phase heat dissipation loop active control method based on the system of claim 1 is characterized in that a pressure signal (P1) in the compensation cavity (9) is acquired through the first pressure sensor (2), a pressure signal (P2) at the steam outlet of the evaporator (8) is acquired through the second pressure sensor (6), then the pressure signal (P1) and the pressure signal (P2) are transmitted to the PI control system (7), and the PI control system (7) outputs pulse electric signals to the first electromagnetic valve (1) and the second electromagnetic valve (3) after operation and controls the opening degree of the first electromagnetic valve (1) and the second electromagnetic valve (3);
the temperature information of the chip exposed surface (12) acquired by the first temperature sensor (4) and the second temperature sensor (5) is transmitted to a PI control system (7), the PI control system (7) carries out real-time processing by adopting a moving average algorithm to obtain an average value, whether thin film evaporation is formed at the bottom of the capillary core or not is judged according to the average value, if the thin film evaporation is formed, the PI control system (7) does not send a pulse signal, if the thin film evaporation is not formed, the PI control system (7) outputs the pulse signal, and the first electromagnetic valve (1) and the second electromagnetic valve (3) are controlled until the thin film evaporation is formed at the bottom of the capillary core.
8. The active control method for two-phase heat dissipation loop of the system of claim 7, wherein the thin film evaporation is formed when the following two conditions are satisfied: (a) the vapor pressure calculated according to the second pressure sensor (6) exceeds the pressure of the liquid in the compensation chamber (9); (b) the average temperature value of 20-30 data points acquired by the first temperature sensor (4) is used as a reference, the moving average value of the temperature acquired by the first temperature sensor (4) on the surface of the chip exposed surface (12) is reduced by 5%, and meanwhile, the moving average value of the temperature acquired by the second temperature sensor (5) on the surface of the chip exposed surface (12) is reduced by 5% by using the average temperature value of 20-30 data points acquired by the second temperature sensor (5) as a reference.
9. The active control method for the two-phase heat dissipation loop of the system as claimed in claim 7, characterized in that the collection frequency of the first pressure sensor (2) and the second pressure sensor (6) is 50-100 data points per second, and the collection frequency of the first temperature sensor (4) and the second temperature sensor (5) is 1-3 data points per second.
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