A cooling system and a cooling method of double working fluid pulse spray flash evaporation heat transfer

Abstract

The present application relates to the field of spray cooling, and in particular to a cooling system and a cooling method for double-working-fluid pulsed spray flash evaporation heat transfer, the cooling system comprising a heat exchange assembly, a first working-fluid source, a second working-fluid source, a pulsed spray system, and a control system; the pulsed spray system is used to spray R134a or RE170 stored in the first working-fluid source and water stored in the second working-fluid source to the heat dissipation surface of the heat exchange assembly; the cooling method comprises monitoring the temperature of the heat dissipation surface of the heat exchange assembly and the vacuum degree of the environment in which the heat dissipation surface is located in real time, and calculating the pulsed spray frequency, the time-averaged volume flow density, and the duty cycle according to the temperature and the vacuum degree, and controlling the pulsed spray system to select one of the first working-fluid source or the second working-fluid source for spray. The embodiments of the present application propose to select different working-fluids according to the vacuum degree of the environment to spray the heat dissipation surface of the heat exchanger, and at the same time, to realize efficient cooling by using the pulse technology, thereby solving the problem of poor effect of traditional cooling technology in a microgravity environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flash and boiling, in particular to a double working medium pulse spray flash heat transfer cooling system and a cooling method. BACKGROUND

[0002] The space laser metal additive manufacturing technology is a leading manufacturing process, which can realize high-precision and high-performance metal part manufacturing in a microgravity environment. However, a laser generates a large amount of heat during the machining process. In the microgravity environment, the cooling effect of the flowing liquid boiling heat transfer technology is poor. The reason is that the flowing liquid is easily affected by the microgravity condition in the heat transfer process. The gravity effect is significant along the long pipe, so that the gas-liquid interface effect occurs along the pipe. Therefore, the flowing liquid is difficult to take away the heat required by the laser under the constraints of limited weight and power and vibration. After the flowing liquid absorbs heat, it still needs to dissipate its heat to the payload cabin, thereby increasing the components and other equipment in the rocket. SUMMARY

[0003] The purpose of the present application is to provide a double working medium pulse spray flash heat transfer cooling system and a cooling method to solve the problem of how to cool equipment in a microgravity test environment.

[0004] To solve the above technical problems, the present application specifically provides the following technical solutions:

[0005] A double working medium pulse spray flash heat transfer cooling system, comprising a heat exchange assembly, a first working medium source, a second working medium source, a pulse spray system and a control system;

[0006] The pulse spray system is used to spray R134a or RE170 stored in the first working medium source and water stored in the second working medium source to the heat dissipation surface of the heat exchange assembly;

[0007] The control system monitors the temperature of the heat dissipation surface of the heat exchange assembly and the vacuum degree of the environment in which it is located in real time, and controls the pulse spray system to select one of the first working medium source or the second working medium source for spraying, and calculates the pulse spray frequency and the time-averaged volume flow density according to the following formula, and then obtains the duty cycle of the spray:

[0008]

[0009] Wherein, St is the Strouhal number, f is the spray frequency, is the characteristic length of the spray, is the time-averaged volume flow density, τ is the inverse of the spray frequency f, Bo * is the modified boiling number, q NB is the heat flow obtained according to the experiment, μf H is the heat of vaporization, ρ fg H is the heat of vaporization, ρ g H is the heat of vaporization, ρ f H is the heat of vaporization, ρ

[0010] Further, when the heat load of the heat exchange assembly is lower than a preset threshold, the pulse spray system selects a duty cycle of 40% to 60%; when the heat load of the heat exchange assembly is higher than the preset threshold, a duty cycle of 80% to 100% is selected.

[0011] Further, the heat exchange assembly is connected to a laser, for conducting the temperature of the laser to the heat dissipation surface of the heat exchange assembly, the control system monitors the temperature of the heat exchange surface of the heat exchange assembly and the laser in real time, and controls the opening and closing and the degree of opening and closing of the switch valve accordingly, the control system monitors the vacuum degree of the environment in which the heat exchange assembly is located in real time, and controls the three-way valve to selectively connect one of the first working medium source and the second working medium source.

[0012] Further, the first working medium source includes a first container and R134a or RE170 stored in the first container, the second working medium source includes a second container and water stored in the second container, and a third container connected to the second container and high-pressure gas stored in the third container.

[0013] Further, the pulse spray system includes a three-way valve, a filter, a switch valve, and a spray assembly.

[0014] The output end of the spray assembly faces the heat dissipation surface of the heat exchange assembly, the input end of the spray assembly is connected to the switch valve, and the filter is installed between the three-way valve and the switch valve.

[0015] The three-way valve is connected to the first working medium source, the second working medium source, and the switch valve, so that the spray assembly can be selectively connected to one of the first working medium source and the second working medium source.

[0016] Further, the heat exchange assembly includes a micro-channel heat exchanger, a liquid pump, and a third working medium circulated between the laser and the micro-channel heat exchanger by the liquid pump.

[0017] Further, the control system comprises: a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor, a pressure sensor and a controller; wherein the first temperature sensor is arranged in the laser, the second temperature sensor is arranged in the return pipeline of the third working medium between the laser and the micro-channel heat exchanger, the third temperature sensor is arranged in the inflow pipeline of the third working medium between the laser and the micro-channel heat exchanger, the fourth temperature sensor and the pressure sensor are arranged in the working medium pipeline between the three-way valve and the on-off valve, and the controller controls the opening and closing of the on-off valve and the switching of the three-way valve according to a preset control program and a determination criterion.

[0018] A cooling method of double-working-medium pulse spray flash heat transfer, the method uses the cooling system, and the method comprises the following steps:

[0019] In a non-vacuum environment, the first working medium source sprays a liquid or gas-liquid mixture comprising R134a or RE170 to the heat dissipation surface of the heat exchange assembly, and the heat of the heat exchange assembly is taken away through flash evaporation and boiling;

[0020] In a vacuum environment, the second working medium source sprays a liquid mist comprising water to the heat dissipation surface of the heat exchange assembly after atomization, and the heat of the heat exchange assembly is taken away through flash evaporation and boiling of the liquid.

[0021] Further, the heat dissipation surface of the heat exchange assembly is pre-cooled for a preset duration before the additive manufacturing system is operated.

[0022] Further, the power and temperature of the laser and the temperature of the heat dissipation surface of the heat exchange assembly are monitored in real time, and the opening and closing of the on-off valve are adjusted, so that the spray duty ratio and spray flow, spray frequency are adjusted.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] Embodiments of the present application propose a cooling system and a cooling method for selecting different working medium pairs to spray and flash evaporate the heat dissipation surface of the heat exchanger according to the vacuum degree of the environment, and high-efficiency cooling is realized by using pulse technology, thereby solving the problem of poor effect of traditional cooling technology in a microgravity environment. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only exemplary, and other implementation drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0026] Figure 1 System block diagram of the embodiment of the present application;

[0027] Figure 2 Switching valve pulse control strategy diagram of the embodiment of the present application;

[0028] Figure 3 Characteristics of residual liquid on hot surface under different average heat flux densities - pulse spray enhances liquid utilization efficiency diagram of the embodiment of the present application;

[0029] Figure 4 Comparison diagram of liquid film flow characteristics on spray cooling surface under normal microgravity conditions of the embodiment of the present application;

[0030] Figure 5 Pulse spray cooling heat transfer characteristics prediction method diagram of the embodiment of the present application;

[0031] Figure 6 Pulse spray cooling heat transfer characteristics law diagram of the embodiment of the present application;

[0032] The reference signs in the drawings represent the following respectively:

[0033] 1 - third container; 2 - second container; 3 - first container; 4 - three-way valve; 5 - filter; 6 - fourth temperature sensor; 7 - pressure sensor; 8 - switching valve; 9 - spray assembly; 10 - micro-channel heat exchanger; 11 - liquid pump; 12 - laser; 13 - second temperature sensor; 14 - third temperature sensor; 15 - first temperature sensor. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0035] The present application proposes a double-working fluid pulse spray flash heat transfer cooling system and cooling method, which uses different working fluid pairs to cool the laser 12 in different working conditions, hereinafter referred to as cooling system and cooling method.

[0036] Reference Figure 1 The cooling system comprises a heat exchange assembly, a first working fluid source, a second working fluid source, a spray assembly 9, a switching valve 8, a three-way valve 4, and a control system.

[0037] The heat exchange assembly is connected with the laser 12, and is used to conduct the temperature of the laser 12 to the heat dissipation surface of the heat exchange assembly; the first working medium source comprises a first container 3 and a first working medium stored in the first container 3; the second working medium source comprises a second container 2 and a second working medium stored in the second container 2, and a third container 1 connected with the second container 2 and a high-pressure gas stored in the third container 1; the output end of the spraying assembly 9 is directed to the heat dissipation surface of the heat exchange assembly, and the input end of the spraying assembly 9 is connected with the on-off valve 8; the three-way valve 4 is connected with the first container 3, the second container 2 and the on-off valve 8, so that the spraying assembly 9 is selectively connected with one of the first working medium source and the second working medium source; the control system is used to monitor the temperature of the laser 12 in real time, and control the opening and closing and the opening and closing degree of the on-off valve 8 and the connection passage of the three-way valve 4 according to the temperature of the laser 12, so that the first working medium and the second working medium can be sprayed to the heat dissipation surface of the heat exchange assembly at different flow rates respectively.

[0038] Preferably, the spraying assembly 9 comprises a plurality of atomizing nozzles uniformly distributed in a rectangular array or a circular array, and the heat dissipation surface of the heat exchange assembly is a large-area plane.

[0039] Preferably, the first working medium is freon which meets the requirement of being stored at a certain pressure at room temperature, and R134a is the best choice and RE170 is the second choice; the R134a in the first container 3 is in liquid state, and the first working medium leaves the first container 3 by using the pressure of the first working medium as a power source, and is sprayed to the surface of the laser 12 through the spraying assembly 9; the R134a leaving the spraying assembly 9 is in liquid state or gas-liquid mixture, and the specific physical form of the R134a depends on the length of the pipeline between the first container 3 and the spraying assembly 9; when the length of the pipeline is short, the R134a is in liquid state; and when the length of the pipeline is long, the R134a is in gas-liquid mixture.

[0040] Preferably, the second working medium is water, and the second working medium source further comprises a third container 1 connected with the second container 2 and a high-pressure gas stored in the third container 1; the second working medium uses the high-pressure gas as a power source, and the high-pressure gas drives the second working medium to leave the second container 2 after being delivered to the inside of the second container 2; and the second working medium is sprayed to the heat dissipation surface of the heat exchange assembly after being atomized by the spraying assembly 9.

[0041] The advantage of this design is that the laser metal additive manufacturing technology relies on gas protection, so that the laser metal additive manufacturing system and the second working medium can share one high-pressure gas source, thereby simplifying the complexity of the system.

[0042] Preferably, a filter 5 is installed between the three-way valve 4 and the on-off valve 8, and the filter 5 is used to filter the first working medium and the second working medium.

[0043] Further, the heat exchange component is a water-cooled heat exchanger, and the heat exchange component comprises a micro-channel heat exchanger 10, a liquid pump 11, and a third working medium circulating between the laser 12 and the micro-channel heat exchanger 10 through the liquid pump 11. The liquid pump 11 is preferably a water pump, and the third working medium is preferably water.

[0044] Further, the control system comprises a first temperature sensor 15, a second temperature sensor 13, a third temperature sensor 14, a fourth temperature sensor 6, a pressure sensor 7, and a controller.

[0045] The first temperature sensor 15 is arranged inside the laser 12, the second temperature sensor 13 is arranged in a return pipeline of the third working medium between the laser 12 and the micro-channel heat exchanger 10, the third temperature sensor 14 is arranged in an inflow pipeline of the third working medium between the laser 12 and the micro-channel heat exchanger 10, and the fourth temperature sensor 6 and the pressure sensor 7 are arranged in a working medium pipeline between the three-way valve 4 (or the filter 5) and the on-off valve 8.

[0046] The controller is communicatively connected with the first temperature sensor 15, the second temperature sensor 13, the third temperature sensor 14, the fourth temperature sensor 6, the pressure sensor 7, the three-way valve 4, and the on-off valve 8. The controller automatically determines appropriate control parameters according to a preset control program and a determination criterion, controls the opening and closing of the on-off valve 8, and thus realizes the intermittent opening of the spray assembly 9 at a certain duty ratio and frequency, and further realizes the precise control of the working temperature of the laser 12.

[0047] In addition, it is necessary to ensure that the sum of the sensible heat and the latent heat of the first working medium and the second working medium is not less than the total heat dissipation amount of the laser 12 during the working time.

[0048] The cooling system executes different cooling methods in different working conditions, and the cooling method comprises the following steps:

[0049] In the first working condition (non-vacuum environment), the first working medium (in a liquid state or a gas-liquid mixed state) is sprayed to the heat dissipation surface of the heat exchange component, and the heat of the heat exchange component is taken away through flashing and boiling;

[0050] In the second working condition (vacuum environment), the second working medium (in a liquid state) is atomized and sprayed to the heat dissipation surface of the heat exchange component, and the heat of the heat exchange component is taken away through flashing and boiling.

[0051] The first working condition is designed for a closed cabin of a sounding rocket, and the interior of the closed cabin is a non-vacuum environment. The second working condition is designed for a non-closed cabin of a sounding rocket, and the interior of the non-closed cabin is a vacuum environment.

[0052] In addition, the cooling method further comprises the following steps:

[0053] Pre-cooling: Before the additive manufacturing system is running, pre-cooling is performed for a preset duration (usually not less than 5 minutes) using the first working medium or the second working medium to avoid temperature surge caused by transient heat flow peak when the laser 12 is turned on.

[0054] Conventional cooling: After the cooling is turned on, the pressure in front of the spray assembly 9 is maintained unchanged, the pressure of the first working medium sprayed is the saturation pressure of the first container 3 at the current temperature, and the pressure of the second working medium is controlled at 0.2 MPa. The controller monitors the power and temperature of the laser 12 and the temperature of the heat exchange assembly in real time, and adjusts the opening and closing of the on-off valve 8 in real time to adjust the spray duty cycle, spray flow, and spray frequency to obtain different heat transfer characteristics.

[0055] For example, when the heat flow of the laser 12 is low, a low duty cycle and low frequency scheme is adopted to improve the evaporation efficiency and reduce liquid consumption. When the heat flow of the laser 12 is high, the evaporation rate of the working medium is high itself, and a high duty cycle and high frequency scheme (duty cycle not less than 50%, frequency not less than 15 Hz) is adopted to ensure high heat transfer efficiency to control the surface temperature.

[0056] In addition, since the above-mentioned cooling system uses two different working media, and since the surface flow pattern and heat transfer law of different working media under different thermal conditions are significantly different, the spray parameters such as spray pressure or spray height need to be changed when cooling the heat dissipation surface of the heat exchange assembly using different working media or when facing different thermal loads.

[0057] In order to adapt the cooling system to the change of the working medium without changing the spray pressure or spray height, on the basis of the above-mentioned cooling system, the present application further proposes a pulse spray cooling technology, which refers to the pulse control strategy of the on-off valve 8 shown in Figure 2 The on-off valve 8 is preferably a high-speed electromagnetic valve.

[0058] Referring to the characteristics of the residual liquid on the hot surface under different average heat flux densities shown in Figure 3 It can be seen that in the low heat flow stage, the liquid on the surface has been completely evaporated and utilized in the spray stop period, so that the pulse spray improves the liquid utilization efficiency and reduces the cooling medium consumption; and in the high heat flow stage, the liquid on the surface is quickly evaporated in the spray stop period, at which time the duty cycle and the frequency need to be increased to ensure that the surface does not dry for a long time.

[0059] The specific parameters of the pulse control strategy of the on-off valve 8 can refer to the duty cycle / frequency and heat transfer characteristic relationship data shown in Figure 3 and Figure 5 According to Figure 4The relationship data of the heat transfer characteristics of the shown spray cooling under microgravity is determined and the duty cycle and frequency parameter combination scheme of the characteristics under different working conditions is selected to ensure the controllability and predictability of the heat transfer characteristics under microgravity.

[0060] The advantage of the pulse spray cooling technology is that the boundary condition of heat exchange in each cycle can be ensured to be similar or fixed by only changing the duty cycle and frequency, so that when the working medium is changed, the parameters such as the spray pressure and the spray assembly height do not need to be changed.

[0061] On the other hand, the present application also solves the technical problem of the uncertainty of the liquid film flow and heat transfer process caused by the lack of gravity when the existing spray cooling technology is applied to the microgravity environment.

[0062] Under the normal gravity environment, gravity is an important factor affecting the flow of the liquid film, and under the microgravity environment, the influence of gravity is greatly weakened, and the constraint effect of surface tension on the thin liquid film with a thickness of about 100 microns is more obvious, resulting in that the dynamic characteristics such as droplet spreading, liquid film flow speed and thickness are completely different from those under the normal gravity condition.

[0063] Therefore, the spray cooling parameters under the normal gravity environment cannot be directly applied to the microgravity environment.

[0064] In addition, the existing continuous spray scheme has low evaporation efficiency, medium waste, and it is difficult to control under the space microgravity condition, and although the pulse spray technology can improve the efficiency, there is no public heat transfer prediction model, which leads to the inability to accurately select the optimal process parameters such as spray pressure, duty cycle and frequency under microgravity.

[0065] To solve the above problems, the present application further proposes a method for predicting the duty cycle and frequency of pulse spray based on the heat transfer characteristics of pulse spray.

[0066] The present application divides the dynamic heat exchange process of pulse spray into a spraying period and an intermittent period, the spraying period is similar to continuous spray, and the intermittent period utilizes the rapid evaporation of residual liquid to strengthen heat exchange, thereby improving the liquid utilization efficiency.

[0067] The present application introduces the Strouhal number St, and the frequency f of the pulse spray and the time-averaged volume flow density The two key variables are related to quantify the degree of discretization of the spray.

[0068] In the heat system of the spray cooling, the balance relationship between evaporation and flow is as follows:

[0069] qA=ηQ m H fg +Q m C p ΔT sub

[0070] Where q is the heat flux, A is the area involved in heat transfer, η is the evaporation efficiency, Q m is the amount of fluid at the hot surface, H fg is the latent heat of vaporization, C p is the specific heat capacity, ΔT sub is the subcooling degree.

[0071] The transient mass flow rate is regarded as the average value of the harmonic, the transient change characteristics of the mass flow rate are considered by introducing the characteristic time, the Strouhal number is rewritten to characterize the idea, and the definition of the St number is as follows:

[0072]

[0073] Where, is the characteristic length of the spray, τ is the reciprocal of the spray frequency f, and represents the characteristic time of the transient mass flow rate.

[0074] The St number characterizes the relative influence between the injection and the intermittent cycle alternation effect (reflected by f) and the multi-droplet-wall interaction (reflected by ).

[0075] Based on the experimental data under microgravity conditions, the present application establishes a microgravity environment two-phase heat transfer characteristic prediction correlation based on the Jakob number Ja, the modified boiling number Bo * (including the St number) and the Weber number We:

[0076]

[0077] Where Bo * is the modified boiling number, We is the Weber number, Ja is the Jakob number, q NB is the heat flux obtained according to the experiment, μ f is the viscosity, H fg is the latent heat of vaporization, ρ g is the gas phase density, ρ f is the liquid phase density.

[0078] The process of calculating the pulse spray frequency f and the time-averaged volume flow density is as follows:

[0079] First, the Ja number is calculated, and the Ja number calculation formula is

[0080]

[0081] Then, the Bo * value is determined through the microgravity environment two-phase heat transfer characteristic prediction correlation,

[0082] Subsequently, the We number is calculated, and the We number calculation formula is:

[0083]

[0084] Where σ is the surface tension.

[0085] Furthermore, the calculation of the implementation of Bo * The number of St values ​​required for the value.

[0086] Finally, based on the definition of the St number, determine a set or an optimal pulse spray frequency f and time-averaged volumetric flow rate density. The combination of .

[0087] refer to Figure 6 When the heat load is small, a lower duty cycle (such as DC 40%-60%) and a suitable frequency can be used; when the heat load is large, a higher duty cycle (such as DC 80%-90% or even continuous spray DC 100%) should be used, and a corresponding frequency should be matched.

[0088] In pulse spray control, the pulse spray frequency f is a separate variable, representing the characteristic time and the time-averaged volumetric flow rate density. It is also a single variable representing the characteristic velocity.

[0089] At a given fixed injection pressure, the time-averaged volumetric flow rate density There is a one-to-one relationship between duty cycle and volumetric flow rate density; the larger the duty cycle, the higher the volumetric flow rate density. The smaller the value, the more specific the correspondence is, using the following method:

[0090] The hourly average volumetric flow rate density is obtained by measuring the flow rate at a duty cycle of 100% and dividing it by the surface area. When the duty cycle is 90%, the hourly average volumetric flow rate density When reduced to a duty cycle of 100% 90%; when the duty cycle is 50%, the hourly average volumetric flow rate density When reduced to a duty cycle of 100% 50%, and so on.

[0091] exist Figure 6 The approximate pulse spray frequency f and duty cycle (time-average volumetric flow rate density) are given. Based on the combination of these, those skilled in the art can implement it accordingly.

[0092] In this way, the present invention ensures the controllability and predictability of heat transfer characteristics under microgravity, and solves the technical problem that existing spray flash heat transfer technology is difficult to apply directly to microgravity environments.

[0093] The above examples are only exemplary embodiments of the present application and are not intended to limit the present application, and the protection scope of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the present application within the spirit and protection scope of the present application, and such modifications or equivalent replacements are also considered as falling within the protection scope of the embodiments of the present application.

Claims

1. A cooling system for dual-working-fluid pulse spray flash evaporation heat transfer, characterized in that, This includes heat exchange components, a first working fluid source, a second working fluid source, a pulse spray system, and a control system; The pulse spray system is used to spray the R134a or RE170 stored in the first working fluid source and the water stored in the second working fluid source onto the heat dissipation surface of the heat exchange component. The control system monitors the temperature of the heat exchanger's surface and the vacuum level of its surroundings in real time, and accordingly controls the pulse spray system to select either the first or second working fluid source for spraying. The system calculates the pulse spray frequency and hourly average volumetric flow rate density using the following formulas to determine the spray duty cycle: ； ； Where St is the Strouhal number and f is the spray frequency. It is the characteristic length of the spray. It is the time-averaged volumetric flow rate density, and τ is the reciprocal of the spray frequency f. For the corrected boiling number, Based on the heat flow obtained from the experiment, Viscosity, For latent heat of vaporization, The density is the gas phase density. Let be the liquid phase density, We be the Weber number, and Ja be the Jacobian number.

2. The cooling system for dual-working-fluid pulse spray flash heat transfer according to claim 1, characterized in that, When the heat load of the heat exchange component is lower than the preset threshold, the pulse spray system selects a duty cycle of 40% to 60%; when the heat load of the heat exchange component is higher than the preset threshold, it selects a duty cycle of 80% to 100%.

3. The cooling system for dual-working-fluid pulse spray flash heat transfer according to claim 1, characterized in that, The first working fluid source includes a first container (3) and R134a or RE170 stored inside it, the second working fluid source includes a second container (2) and water stored inside it, and a third container (1) connected to the second container (2) and high-pressure gas stored inside it.

4. The cooling system for dual-working-fluid pulse spray flash heat transfer according to claim 1, characterized in that, The pulse spray system includes: a three-way valve (4), a filter (5), a switching valve (8), and a spray assembly (9); The output end of the spray assembly (9) faces the heat dissipation surface of the heat exchange assembly, the input end of the spray assembly (9) is connected to the switching valve (8), and the filter (5) is installed between the three-way valve (4) and the switching valve (8). The three-way valve (4) connects the first working fluid source, the second working fluid source and the switching valve (8), thereby allowing the spray assembly (9) to be selectively connected to either the first working fluid source or the second working fluid source.

5. The cooling system for dual-working-fluid pulse spray flash heat transfer according to claim 4, characterized in that, The heat exchange component is connected to the laser (12) to conduct the temperature of the laser (12) to the heat dissipation surface of the heat exchange component. The control system monitors the temperature of the heat exchange surface of the heat exchange component and the laser (12) in real time, and controls the opening and closing of the switching valve (8) and the degree of opening and closing accordingly. The control system monitors the vacuum level of the environment in which the heat exchange component is located in real time, and controls the three-way valve (4) to selectively connect to one of the first working fluid source and the second working fluid source accordingly.

6. The cooling system for dual-working-fluid pulse spray flash heat transfer according to claim 5, characterized in that, The heat exchange assembly includes a microchannel heat exchanger (10), a liquid pump (11), and a third working fluid that circulates between the laser (12) and the microchannel heat exchanger (10) via the liquid pump (11).

7. The cooling system for dual-working-fluid pulse spray flash heat transfer according to claim 6, characterized in that, The control system includes: a first temperature sensor (15), a second temperature sensor (13), a third temperature sensor (14), a fourth temperature sensor (6), a pressure sensor (7), and a controller; wherein, the first temperature sensor (15) is disposed inside the laser (12), the second temperature sensor (13) is disposed in the return pipeline of the third working fluid between the laser (12) and the microchannel heat exchanger (10), the third temperature sensor (14) is disposed in the inlet pipeline of the third working fluid between the laser (12) and the microchannel heat exchanger (10), the fourth temperature sensor (6) and the pressure sensor (7) are disposed in the working fluid pipeline between the three-way valve (4) and the switching valve (8), and the controller controls the opening and closing of the switching valve (8) and the switching of the three-way valve (4) according to a preset control program and judgment criteria.

8. A cooling method for dual-working-fluid pulse spray flash heat transfer, characterized in that, The cooling method uses the system of any one of claims 5-7, and the method comprises the following steps: In a non-vacuum environment, the first working fluid source sprays a liquid or gas-liquid mixture including R134a or RE170 onto the heat dissipation surface of the heat exchange component, and removes the heat of the heat exchange component through flash evaporation and boiling. In a vacuum environment, the second working fluid source atomizes a liquid including water and sprays it onto the heat dissipation surface of the heat exchange component, whereby the heat of the heat exchange component is carried away through the flash evaporation and boiling of the liquid.

9. The cooling method for dual-working-fluid pulse spray flash heat transfer according to claim 8, characterized in that, Before the additive manufacturing system is put into operation, the heat dissipation surface of the heat exchange component is pre-cooled for a preset time.

10. A cooling method for dual-working-fluid pulse spray flash heat transfer according to claim 8, characterized in that, The power and temperature of the laser (12) and the temperature of the heat dissipation surface of the heat exchange component are monitored in real time, and the opening and closing of the switching valve (8) are adjusted to adjust the spray duty cycle, spray flow rate and spray frequency.

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