Low-temperature liquefied natural gas spray cooling performance test system and test method

Abstract

The invention relates to a low-temperature liquefied natural gas spray cooling performance test system and a test method, belongs to the technical field of low-temperature fuel spray cooling, and solves the problem that a test system and a test method for taking liquefied natural gas fuel as a spray cooling material are lacked in the prior art. And the performance of the liquefied natural gas fuel as the spray cooling material cannot be accurately analyzed. The test system comprises a double-layer structure spraying chamber, a nozzle, a heat source and a data acquisition system, lNG mist sprayed by the nozzle flows in the inner space of the double-layer structure mist spraying chamber; liquid nitrogen flows in the interlayer space of the double-layer structure spraying chamber and is used for low-temperature cooling of LNG spraying. According to the test system, a double-layer heat preservation structure is adopted, and the LNG partially gasified due to storage and transportation can be cooled by using low-temperature liquid nitrogen, so that the phase change heat absorption capacity of the LNG is exerted in spray cooling. And meanwhile, the influence of the external environment on the test result can be well isolated, and the external interference is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of cryogenic fuel spray cooling test, and in particular relates to a cryogenic liquefied natural gas spray cooling performance test system and a test method. Background Art

[0002] With the continuous miniaturization and integration of electronic components, high heat flux density has become the main feature of electronic devices. When the device temperature exceeds the normal operating range, it will seriously affect the reliability and performance of the system. The heat dissipation problem in electronic devices has become a major challenge hindering their development. Traditional cooling technology is not enough to achieve lower surface temperature and uniform heat dissipation of equipment under high heat flux. Spray cooling is now a commonly used phase change cooling method.

[0003] The phase change temperature of the working fluid determines its application scenario in spray cooling. Compared with room temperature working conditions, the efficiency of laser weapons operating at 110K is increased by 40%. In addition, the crystals inside the laser weapon expand as the temperature increases, which changes the wavelength of the output beam and reduces the output power. In order to maintain a stable output, the allowable temperature change during the operation of the laser weapon at room temperature is 2K, and correspondingly, the temperature change range increases to 6K at low temperatures. Therefore, spray cooling with cryogenic working fluids is an effective way to deal with the heat load of laser weapons. The most commonly used cryogenic fluid on aircraft is liquid nitrogen, which has a phase change temperature of 77K at atmospheric pressure. Although liquid nitrogen meets the requirements of providing a low-temperature combat environment for laser weapons, its latent heat of evaporation is low, at 199kJ / kg. In addition, as a consumable heat sink, liquid nitrogen can only be used to inertize the fuel tank or directly discharge it from the aircraft after absorbing heat. Therefore, the use of liquid nitrogen will cause additional fuel loss to the flight. In contrast, another cryogenic fluid, LNG, also has a low boiling point (112K), but a significantly higher latent heat of evaporation (510kJ / kg). In addition, LNG can be burned as fuel in engines after absorbing heat to provide thrust or generate electricity.

[0004] The development of electronic equipment and high-energy pulse devices, coupled with the increase in aircraft speed, has brought major challenges to aircraft thermal management. In order to improve the heat dissipation capacity of aircraft, designing a low-temperature fuel thermal management system has become one of the research hotspots in recent years. However, there is still a lack of analytical research on the cooling performance of low-temperature fuels. Therefore, the present invention designs a spray cooling test system for cryogenic fuel LNG to study the heat transfer characteristics of LNG spray cooling. Summary of the invention In view of the above problems, the present invention provides a liquefied natural gas (LNG) spray cooling test system and test method, which solves the problem in the prior art that there is a lack of test systems and methods for using liquefied natural gas (LNG) fuel as a spray cooling material, and that the performance of liquefied natural gas (LNG) fuel as a spray cooling material cannot be accurately analyzed.

[0005] The present invention provides a cryogenic liquefied natural gas spray cooling performance test system, comprising a double-layer structure spray chamber, a nozzle, a heat source and a data acquisition system; The nozzle is arranged in the double-layer structure spray chamber; the heat source is arranged in the double-layer structure spray chamber, opposite to the nozzle; The double-layer structure spray chamber includes an outer layer and an inner layer, the outer layer and the inner layer form a sandwich space, and the inner layer forms an internal space; the nozzle sprays LNG spray toward the heat source in the internal space of the double-layer structure spray chamber; liquid nitrogen flows in the sandwich space of the double-layer structure spray chamber to cryogenically cool the LNG spray; The data acquisition system is connected to the heat source and is used for real-time monitoring of the temperature of the heat source. Optionally, the double-layer structure spray chamber further includes a liquid nitrogen inlet and a liquid nitrogen spray chamber outlet; the liquid nitrogen inlet is arranged at the bottom of the double-layer structure spray chamber; and the liquid nitrogen spray chamber outlet is arranged at the top of the double-layer structure spray chamber.

[0006] Optionally, a double-layer structure pipeline is also included, and the double-layer structure pipeline is connected to the nozzle.

[0007] Optionally, a liquid nitrogen inlet is provided at one end of the double-layer structure pipeline close to the double-layer structure spray chamber, and the liquid nitrogen flows into the double-layer structure pipeline through the liquid nitrogen inlet.

[0008] Optionally, the double-layer structure pipeline includes an outer layer pipeline and an inner layer pipeline; LNG flows in the inner layer pipeline of the double-layer structure pipeline; liquid nitrogen flows in the outer layer pipeline of the double-layer structure pipeline; and the liquid nitrogen in the double-layer structure pipeline flows in the opposite direction to the LNG.

[0009] Optionally, the heat source includes a heating copper column; the top end of the heating copper column is penetrated into the double-layer structure spray chamber.

[0010] Optionally, an LNG storage tank and a liquid nitrogen storage tank are also included; the LNG storage tank and the liquid nitrogen storage tank are respectively connected to the double-layer structure spray chamber.

[0011] On the other hand, the present invention also discloses a method for testing the performance of cryogenic liquefied natural gas spray cooling. The cryogenic liquefied natural gas spray cooling performance test system is used to perform a cryogenic liquefied natural gas spray cooling performance analysis test. The specific steps are as follows: Adjust the distance between the nozzle and the heat source; polish the surface roughness of the heat source; Use cryogenic liquefied natural gas to blow out the air in the test system; after the air is blown out, use LNG and liquid nitrogen to cool the test system simultaneously; Adjust the output power of the heat source; The temperature change of the heat source is monitored by the data acquisition system and the data receiving mechanism. When the temperature change meets the change threshold requirement, the test system reaches a stable state, records the current test state and saves the test data.

[0012] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The liquefied natural gas spray cooling test system of the present invention adopts a double-layer structure, which can not only play a good heat preservation effect, but also use low-temperature liquid nitrogen to cool the LNG that is partially gasified due to storage and transportation, thereby ensuring that the phase change heat absorption capacity of LNG is exerted during spray cooling. At the same time, the double-layer system structure can well isolate the influence of the external environment on the test results and reduce external interference.

[0013] (2) The liquefied natural gas spray cooling test system of the present invention realizes the sealing between the spray chamber and the heat source in a low temperature environment by machining a groove for the polytetrafluoroethylene gasket at the bottom of the spray chamber and welding a stainless steel plate on the top of the copper column, fixing the stainless steel plate with bolts and pressing the polytetrafluoroethylene gasket, thereby ensuring the safe operation of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings are only for the purpose of illustrating particular embodiments and are not to be construed as limiting the invention.

[0015] Figure 1 It is a schematic diagram of the cryogenic liquefied natural gas spray cooling performance test system of the present invention.

[0016] Figure 2 Schematic diagram of the double-layer structure spray chamber of the present invention.

[0017] Figure 3 Schematic diagram of the heat source of the present invention.

[0018] Reference numerals: 101: LNG storage tank; 102: safety valve; 103: flow control valve; 104: flow meter; 105: pressure sensor; 106: temperature sensor; 107: thermal insulation cotton; 108: LNG gasification tank; 109: LNG outlet; 110: data acquisition system; 111: liquid nitrogen storage tank; 112: liquid nitrogen pipeline outlet; 113: pressure control valve; 114: adjustable power supply; 115: heat source; 201: LNG inlet; 202: liquid nitrogen spray chamber outlet; 203: double-layer structure spray chamber; 204: nozzle; 205: polytetrafluoroethylene gasket; 206: LNG spray chamber outlet; 207: heating copper column; 208: heating rod; 209: liquid nitrogen inlet. DETAILED DESCRIPTION

[0019] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein, and therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0020] A specific embodiment of the present invention, as Figure 1-Figure 3 , discloses a liquefied natural gas spray cooling test system, including a double-layer structure spray chamber 203, a nozzle 204, a double-layer structure pipeline, a flow meter 104, a flow control valve 103, a pressure control valve 113, a heat source 115, a sensor, a data acquisition system 110, an LNG vaporization tank 108 and an LNG spray chamber outlet 206.

[0021] The double-layer structure spray chamber 203 includes an outer layer and an inner layer, and a sandwich space is formed between the outer layer and the inner layer, and the inner layer forms an internal space; the nozzle 204 sprays LNG spray toward the heat source 115 in the internal space of the double-layer structure spray chamber 203; liquid nitrogen flows in the sandwich space of the double-layer structure spray chamber to low-temperature cool the LNG spray, effectively reducing the working temperature of the LNG spray cooling and isolating the experiment from the external environment.

[0022] The double-layer structure pipeline is arranged on the top of the double-layer structure spray chamber 203; the double-layer structure pipeline includes an outer layer pipeline and an inner layer pipeline; LNG flows in the inner layer pipeline of the double-layer structure pipeline; liquid nitrogen flows in the outer layer pipeline of the double-layer structure pipeline; the liquid nitrogen in the double-layer structure pipeline flows in the opposite direction to the LNG, which is used to reduce the temperature of the LNG spray and reduce the consumption of liquid nitrogen.

[0023] Furthermore, it also includes an LNG storage tank 101 , an LNG vaporization tank 108 and a liquid nitrogen storage tank 111 ; the LNG storage tank 101 , the LNG vaporization tank 108 and the liquid nitrogen storage tank 111 are all connected to the double-layer structure spray chamber 203 .

[0024] Furthermore, the double-layer structure pipeline also includes a liquid nitrogen pipeline outlet 112 . The liquid nitrogen pipeline outlet 112 is arranged at one end close to the safety valve 102 , and the liquid nitrogen flows out through the liquid nitrogen pipeline outlet 112 .

[0025] Furthermore, the safety valve 102 is disposed between the LNG storage tank 101 and the double-layer structure pipeline.

[0026] Furthermore, a flow control valve 103 and a flow meter 104 are also provided on the double-layer structure pipeline; the flow control valve 103 and the flow meter 104 are sequentially provided on the double-layer structure pipeline from one end close to the safety valve 102 .

[0027] Furthermore, an LNG inlet 201 is provided on the top of the double-layer structure spray chamber 203, and the nozzle 204 extends into the double-layer structure spray chamber 203 through the LNG inlet 201. The double-layer structure pipeline is connected with the nozzle 204 and the LNG storage tank 101, and the liquefied natural gas is input from the LNG storage tank 101 to the nozzle 204.

[0028] Furthermore, the LNG spray chamber outlet 206 is provided through the bottom of the double-layer structure spray chamber 203 , and the LNG heated in the double-layer structure spray chamber 203 flows out from the LNG spray chamber outlet 206 at the bottom.

[0029] Preferably, two LNG spray chamber outlets 206 are provided.

[0030] Furthermore, the LNG spray chamber outlet 206 is connected to the pressure control valve 113; the pressure control valve 113 is connected to the LNG vaporization tank 108; the LNG vaporization tank 108 is connected to the LNG outlet 109, and the LNG outlet 109 leads to the external atmospheric environment.

[0031] Furthermore, the sensor includes a pressure sensor 105 and a temperature sensor 106 , which are arranged at the double-layer structure pipeline at the inlet of the nozzle 204 , at the pipeline between the pressure control valve 113 and the LNG gasification tank 108 , and in the double-layer structure spray chamber 203 .

[0032] The temperature sensor and pressure sensor installed at the double-layer structure pipe in front of the nozzle 204 are used to monitor the state of LNG at the LNG inlet 201. When the temperature data output by the temperature sensor is high (higher than -170°C), the flow rate of liquid nitrogen (LN2) flowing into the double-layer structure pipe near the LNG inlet 201 is increased to reduce the temperature of LNG. Correspondingly, when the temperature is low (lower than -190°C), the flow rate of LN2 flowing into the double-layer structure pipe near the LNG inlet 201 is reduced. When the pressure of the LNG inlet 201 monitored by the pressure sensor is low (lower than 200kPa), the self-pressurization function of the LNG storage tank 101 is turned on to increase the pressure of the LNG inlet 201. Correspondingly, when the pressure is high (higher than 600kPa), the pressure reducing valve on the LNG storage tank 101 is briefly opened to reduce the pressure of the LNG inlet 201.

[0033] The temperature sensor and pressure sensor installed in the double-layer structure spray chamber 203 are used to monitor the environmental state of the LNG after it is sprayed from the nozzle. When the temperature data output by the temperature sensor is high (higher than -160°C), the flow rate of LN2 flowing through the liquid nitrogen inlet 209 into the double-layer structure spray chamber is increased to reduce the temperature of the inner structure. Correspondingly, when the temperature is low (lower than -190°C), the flow rate of LN2 flowing through the liquid nitrogen inlet 209 into the double-layer structure spray chamber is reduced. When the nozzle inlet pressure monitored by the pressure sensor is low (lower than 100kPa), the opening of the pressure control valve 113 is reduced to increase the pressure in the spray chamber. Correspondingly, when the pressure is high (higher than 300kPa), the valve opening is increased to reduce the pressure.

[0034] The temperature sensor and the pressure sensor installed in the pipeline between the pressure control valve 113 and the LNG vaporization tank 108 are used to monitor the state of the LNG discharged from the double-layer structure spray chamber 203.

[0035] Furthermore, the data acquisition system 110 is connected to three K-type thermocouples installed on the heating copper column 207 to monitor the temperature on the heating copper column 207 in real time and obtain data of the temperatures T1, T2 and T3 at the three K-type thermocouples.

[0036] It is understandable that the double-layer structure spray chamber 203 is made of stainless steel, the inner cube space of the spray chamber is a test space for carrying out LNG spray cooling, and the middle interlayer of the double-layer structure is a filling flow area for liquid nitrogen. The liquid nitrogen flowing out of the liquid nitrogen storage tank first flows into the spray chamber from the lower right corner, and then flows out from the upper left corner. The flow path design from bottom to top can satisfy the liquid nitrogen to completely fill the entire interlayer structure. The liquid nitrogen flowing out of the spray chamber interlayer flows into the double-layer pipeline in the system. The double-layer pipeline is used to cool the two-phase natural gas flowing out of the LNG storage tank. Similarly, liquid nitrogen flows in the interlayer of the double-layer pipeline, and LNG flows in the inner layer pipeline. The liquid nitrogen and LNG flow in opposite directions, showing countercurrent heat exchange. This design can better reduce the temperature of LNG.

[0037] The heat source 115 is disposed at the bottom of the double-layer spray chamber 203, directly below the nozzle. A through hole is processed at the bottom of the inner layer of the double-layer spray chamber 203, and the hole diameter is the same as the diameter of the upper half of the top of the heat source 203. d 2 are equal.

[0038] Furthermore, the liquid nitrogen inlet 209 is arranged at the bottom outer layer of the liquid nitrogen sandwich shell, and is connected to the outlet of the LN2 storage tank; the liquid nitrogen spray chamber outlet 202 is arranged at the top outer layer of the liquid nitrogen sandwich shell.

[0039] Furthermore, the heat source 115 includes a heating rod 208, a heating copper column 207 and a heat-insulating cotton 107; the heat-insulating cotton 107 is wrapped around the outer layer of the heating copper column 207, the top of the heating copper column 207 penetrates through the bottom of the double-layer structure spray chamber 203 and penetrates therein, and the upper surface of the heating copper column 207 is directly cooled by the LNG spray sprayed from the nozzle 204. A polytetrafluoroethylene (PTFE) gasket is provided at the connection between the heating copper column 207 and the bottom of the double-layer structure spray chamber 203 for sealing.

[0040] In order to solve the sealing problem caused by the low temperature of LNG, the present invention combines material properties and engineering experience. Polytetrafluoroethylene (PTFE) gasket is the most ideal sealing material between the spray chamber and the heat source. Due to the lack of elasticity, PTFE cannot fix the copper column like a rubber O-ring. Therefore, the present invention designs a new sealing solution. A groove for the polytetrafluoroethylene gasket is set on the outer bottom surface of the inner layer structure of the double-layer structure spray chamber 203, and the depth of the groove is s 1. The depth is slightly smaller than the thickness of the PTFE gasket h p The seal is accomplished by compressing the gasket with a stainless steel plate and six hexagon socket bolts. The steel plate is welded to the copper column to fix its position and improve the seal of the test.

[0041] When in use, the heating method adopts a horizontal buried columnar heating rod. The heating rod 208 is connected to the adjustable power supply 114, and the heat flow is controlled by adjusting the voltage. Figure 3 The heating copper column 207 includes a rectangular parallelepiped base for mounting the heating rod 208, a first diameter section and a second diameter section, the length of the base is the same as the length of the heating rod 208, and the diameter of the front hole is the same as the diameter of the heating rod 208. The diameter of the first diameter section is d 1. The diameter of the second diameter section is d 2. The axial height of the second diameter section is δ 3; A reducer connection platform is provided between the first diameter section and the second diameter section, and the axial height of the reducer connection platform is δ 2. The reducer provides support for the stainless steel plate for welding and sealing. δ 1, and the three mounting holes are used to install three K-type thermocouples respectively. The measured temperature data results are, from bottom to top, the temperature T1 at the first K-type thermocouple, the temperature T2 at the second K-type thermocouple, and the temperature T3 at the third K-type thermocouple. The thickness h0 of the inner layer structure of the double-layer structure spray chamber 203, the axial height of the second diameter section of the heating copper column δ 3. PTFE gasket thickness h p and the thickness of the groove processed on the outside of the spray chamber bottom surface s The relationship between 1 is: .

[0042] This ensures that the upper surface of the copper column extending into the inner layer structure of the double-layer spray chamber is flush with the inner side surface of the inner layer structure.

[0043] Furthermore, the double-layer spray chamber is made of stainless steel with a thickness of h 0, preferably, h 0 is greater than 5mm to ensure the pressure bearing capacity of the structure. The side length of the inner square structure formed by the inner layer of the double-layer spray chamber is h 1. The side length of the outer square structure formed by the outer layer of the double-layer spray chamber is h 2. The thickness of the interlayer space formed between the inner layer and the outer layer h The relationship among the 3 is: .

[0044] During the test, the status of LNG was monitored by multiple temperature and pressure sensors installed in the system. The temperature T1 at the first K-type thermocouple, the temperature T2 at the second K-type thermocouple, and the temperature T3 at the third K-type thermocouple were measured by three K-type thermocouples to obtain the temperature Tw on the surface of the heat source 115 and the heat exchange capacity of LNG spray cooling.

[0045] Furthermore, the liquid nitrogen storage tank 111 is connected to the liquid nitrogen inlet 209 and the connection between the double-layer structure pipeline and the LNG inlet 201; the liquid nitrogen spray chamber outlet 202 is connected to the double-layer structure pipeline near the LNG inlet 201 end, and the liquid nitrogen flowing out of the double-layer structure spray chamber 203 flows into the double-layer structure pipeline from the liquid nitrogen spray chamber outlet 202. A pressure sensor and a temperature sensor are provided between the connection between the double-layer structure pipeline and the LNG inlet 201 and the connection between the liquid nitrogen spray chamber outlet 202 and the double-layer structure pipeline near the LNG inlet 201 end.

[0046] When in use, the valve of the LNG storage tank is opened, and the natural gas is driven by the pressure in the storage tank to flow into the test system through the double-layer structure pipeline. Subsequently, the LNG passes through the flow control valve 103 and the flow meter 104 and enters the double-layer structure spray chamber 203. In the double-layer structure spray chamber 203, the LNG atomized by the nozzle absorbs heat on the surface of the heat source 115 and partially vaporizes, and then flows into the large vaporization tank through the LNG spray chamber outlet 206 and the pressure control valve 113 and is completely vaporized, and finally discharged into the atmosphere through the LNG outlet 109. Liquid nitrogen flows in from the lower right liquid nitrogen inlet 209 and flows out from the upper left, filling the interlayer space of the double-layer structure spray chamber 203. A through hole is opened on the front of the double-layer structure spray chamber, and the CF vacuum internal welding flange is installed by welding. It can be fixed with the CF vacuum blind plate using bolts to form a good and quickly detachable sealing structure, which is convenient for adjusting different test conditions.

[0047] Considering the physical properties of LNG, it is necessary to conduct spray cooling test research in a fully enclosed spray chamber. At the same time, due to storage and transportation, the LNG in the cryogenic tank is partially gasified, which increases the pressure in the tank and puts the LNG in a two-phase state. In order to ensure that the liquefied natural gas at the nozzle outlet is completely liquid and prevent the flash of liquefied natural gas in the spray chamber, a liquid nitrogen precooling test system is constructed.

[0048] Another embodiment of the present invention discloses a method for testing the spray cooling performance of low-temperature liquefied natural gas. The aforementioned low-temperature liquefied natural gas spray cooling performance testing system is used to perform a liquefied natural gas spray cooling performance analysis test. The specific steps are as follows: Step 1. Remove the CF vacuum flange on the front of the double-layer structure spray chamber; adjust the distance between the nozzle and the heating copper column; polish the surface roughness of the heating copper column; reinstall the CF vacuum flange, and stick insulation cotton on the outside of the double-layer structure spray chamber to reduce external heat leakage.

[0049] Preferably, the distance between the nozzle and the heated copper column is varied from 10 mm to 30 mm.

[0050] Preferably, the distance between the nozzle and the heated copper column is 21.5 mm.

[0051] Step 2, open the valve of the LNG storage tank, and use low-temperature liquefied natural gas to blow out the air in the double-layer structure pipeline and the double-layer structure spray chamber in the test system, thereby reducing the interference of air on the test results and preventing the occurrence of icing; after the air is blown away, open the valve of the liquid nitrogen storage tank 111, and use LNG and liquid nitrogen to cool the test system at the same time, thereby achieving rapid cooling of the system.

[0052] Step 3: Regulate the pressure control valve 113 to control the pressure in the double-layer structure spray chamber to prevent flashing of LNG.

[0053] Specifically, the pressure control valve 113 is adjusted to control the pressure in the spray chamber to ensure that the pressure value of the pressure sensor installed on the side of the double-layer structure spray chamber 203 is between 100kPa and 300kPa to prevent flashing of LNG. Preferably, the pressure of the spray chamber in the current example is 235kPa.

[0054] Exemplarily, when the temperature inside the double-layer structure spray chamber 203 is measured to be -165°C and the pressure is 235 kPa by the pressure sensor 105 and the temperature sensor 106, the working conditions for conducting the test are met, the flow control valve 103 is adjusted and the actual flow of the test system is monitored by the flow meter 104 until the flow range required for the test is obtained to be 0.1 kg / min~0.3 kg / min.

[0055] Preferably, the flow rate is 0.29 kg / min, and the pressure control valve 113 is adjusted to control the pressure in the spray chamber to prevent flashing of LNG.

[0056] Step 4, activating the adjustable power supply 114 connected to the heating rod, adjusting the output voltage of the adjustable power supply, and controlling the output power of the heating rod installed in the heating copper column 207; Specifically, the heating power ranges from 50W to 300W, and preferably, the heating power is 78.4W.

[0057] Step 5: Monitor the temperature results of the three K-type thermocouples on the side of the heating copper column 207 through the data acquisition system 110 and the data receiving software installed on the mobile computer. When the temperature results of the temperature T1 at the first K-type thermocouple, the temperature T2 at the second K-type thermocouple, and the temperature T3 at the third K-type thermocouple change less than 1°C (change threshold) within 100 seconds, the test system reaches a stable state, and the temperature of the surface of the heat source 115 is obtained. T w and heat transfer coefficient of LNG spray cooling.

[0058] Specifically, the heat flow under the current working condition is obtained based on the temperature T1 at the first K-type thermocouple and the temperature T3 at the third K-type thermocouple, and the expression is: ; ; in, Indicates the heat transfer heat flux under the current test conditions; represents the thermal conductivity of copper; Indicates the spacing between thermocouples, such as Figure 3 As shown; represents the area of ​​the first diameter section of the heated copper column; The diameter of the first diameter section of the heated copper column.

[0059] Based on the temperature T3 at the third K-type thermocouple, the average temperature T4 on the lower surface of the reducer is obtained, and the expression is: .

[0060] Based on the average temperature T4 of the lower surface of the reducer, the average temperature T5 of the upper surface of the reducer is obtained, and the expression is:

[0061] in, Indicates that the heat conduction process goes along x Coordinates transferred in the axis direction; Represents the cross-sectional area of ​​the heat conduction process; Indicates the position of the lower surface of the reducer corresponding to xCoordinate distance of the axis; Indicates the position of the reducer on the upper surface corresponding to x Coordinate distance of the axis; Represents pi. The temperature of the surface of the heat source 115 is obtained based on the average temperature T5 of the surface of the reducer connection stage T w , the expression is:

[0062]

[0063] in, represents the area of ​​the second diameter section of the heated copper column; Indicates the diameter of the second diameter section of the heating copper column; Indicates the height of the second diameter section of the heated copper column, such as Figure 3 As shown; Based on the temperature of the surface of the heat source 115 T w and the temperature of the LNG at the inlet of the nozzle 204 T liq Obtaining the heat transfer coefficient of LNG spray cooling h , the expression is: .

[0064] Step 6. After completing a set of tests under the current nozzle height and surface roughness test conditions, let the test system stand still. After the spray chamber temperature returns to normal temperature, open the vacuum flange of the spray chamber, adjust the test conditions (nozzle height and surface roughness), and conduct the next set of tests.

[0065] Preferably, the output voltage of the adjustable power supply is adjusted in increments of 5V.

[0066] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A cryogenic liquefied natural gas spray cooling performance test system, characterized in that: It includes a double-layer structure spray chamber, a nozzle, a heat source and a data acquisition system; The nozzle is arranged in the double-layer structure spray chamber; the heat source is arranged in the double-layer structure spray chamber, opposite to the nozzle; The double-layer structure spray chamber includes an outer layer and an inner layer, the outer layer and the inner layer form a sandwich space, and the inner layer forms an internal space; the nozzle sprays LNG spray toward the heat source in the internal space of the double-layer structure spray chamber; liquid nitrogen flows in the sandwich space of the double-layer structure spray chamber to cryogenically cool the LNG spray; The data acquisition system is connected to the heat source and is used for real-time monitoring of the temperature of the heat source.

2. The cryogenic liquefied natural gas spray cooling performance test system according to claim 1, characterized in that: The double-layer structure spray chamber also includes a liquid nitrogen inlet and a liquid nitrogen spray chamber outlet; the liquid nitrogen inlet is arranged at the bottom of the double-layer structure spray chamber; and the liquid nitrogen spray chamber outlet is arranged at the top of the double-layer structure spray chamber.

3. The cryogenic liquefied natural gas spray cooling performance test system according to claim 1, characterized in that: It also includes a double-layer structure pipeline, which is connected with the nozzle.

4. The cryogenic liquefied natural gas spray cooling performance test system according to claim 3, characterized in that: A liquid nitrogen inlet is arranged at one end of the double-layer structure pipeline close to the double-layer structure spray chamber, and liquid nitrogen flows into the double-layer structure pipeline through the liquid nitrogen inlet.

5. The cryogenic liquefied natural gas spray cooling performance test system according to claim 4, characterized in that: The double-layer structure pipeline includes an outer layer pipeline and an inner layer pipeline; LNG flows in the inner layer pipeline of the double-layer structure pipeline; liquid nitrogen flows in the outer layer pipeline of the double-layer structure pipeline; the liquid nitrogen in the double-layer structure pipeline flows in the opposite direction to the LNG.

6. The cryogenic liquefied natural gas spray cooling performance test system according to any one of claims 1 to 5, characterized in that: The heat source comprises a heating copper column; the top end of the heating copper column is penetrated into the double-layer structure spray chamber.

7. The cryogenic liquefied natural gas spray cooling performance test system according to claim 6, characterized in that: It also includes an LNG storage tank and a liquid nitrogen storage tank; the LNG storage tank and the liquid nitrogen storage tank are respectively connected to the double-layer structure spray chamber.

8. A method for testing the spray cooling performance of low-temperature liquefied natural gas, using the spray cooling performance testing system of low-temperature liquefied natural gas according to claim 1 to perform a spray cooling performance analysis test of low-temperature liquefied natural gas, characterized in that: The specific steps are as follows: Adjust the distance between the nozzle and the heat source; polish the surface roughness of the heat source; Use cryogenic liquefied natural gas to blow out the air in the test system; after the air is blown out, use LNG and liquid nitrogen to cool the test system simultaneously; Adjust the output power of the heat source; The temperature change of the heat source is monitored by the data acquisition system and the data receiving mechanism. When the temperature change meets the change threshold requirement, the test system reaches a stable state, records the current test state and saves the test data.

Images