Liquid drop radiation heat exchange experimental device and method
Technical Field
The invention relates to the technical field of liquid drop radiation heat exchange, in particular to a radiation heat exchange experimental device and method for liquid drops in an ultralow-temperature and vacuum environment.
Background
The development of a novel thermal control system is one of the important subjects of spacecraft design and research. In order to overcome the defects that traditional solid surface radiation heat-radiating systems such as a heat pipe type radiator, a loop type radiator and the like are large in mass, low in heat exchange efficiency and required to be protected by an armor, a liquid drop radiator is proposed and widely researched as a light and efficient space heat-exchanging device, a liquid drop radiator converts a heat-exchanging working medium into hundreds of millions of tiny liquid drops to be sprayed out in a piezoelectric ceramic oscillation mode and the like, the tiny liquid drops radiate heat outwards in the process of advancing in space and then are captured by a collector for recycling. At present, a great amount of numerical simulation research is carried out on the radiation heat exchange characteristics of the liquid drop radiator, experimental research is also carried out on the generation and collection of uniform liquid drops, but the experimental research on the radiation heat exchange of the sprayed liquid drops is not carried out yet.
Disclosure of Invention
The invention aims to provide a liquid drop radiation heat exchange experimental device and a liquid drop radiation heat exchange experimental method, and provides the experimental device and the method for researching the radiation heat exchange characteristics of liquid drops under the low-temperature vacuum condition.
In order to achieve the purpose, the invention adopts the following technical scheme:
a liquid drop radiation heat exchange experimental device comprises a low-temperature environment simulation system, a vacuum maintenance system, a liquid drop mounting system, a temperature measurement system and a phase change observation system; the low-temperature environment simulation system is characterized in that the main body of the low-temperature environment simulation system is a cylinder and consists of a cabin cover 7 and a cabin body 8, the cabin body 8 is vacuumized, a coiled pipe 3 is laid on the outer wall of the cabin body 8, liquid nitrogen is contained in the coiled pipe 3 and serves as a coolant, and heat insulation cotton 2 wraps the cabin cover 7, the outer wall of the cabin body 8 and the periphery of the coiled pipe 3; the low-temperature environment simulation system also comprises an air conditioner 5 communicated with the coiled pipe 3, a first valve 12, a second valve 1 and a liquid nitrogen tank 4 which are connected with the air conditioner 5, wherein the liquid nitrogen tank 4 is used for being communicated with the coiled pipe 3; the vacuum maintaining system main body is composed of a vacuum pump 9, the vacuum pump 9 is connected with the cabin body 8 through a pipeline and is used for maintaining a vacuum environment in the cabin body 8; the liquid drop hanging system comprises a fixing support 11, a working medium storage bottle 16, a needle valve 17 and a capillary injection tube 18, wherein the fixing support 11 is arranged in a cabin body 8 and used for fixing a hanging drop thermocouple 6 and preventing the hanging drop thermocouple 6 from shaking to influence hanging drops, the working medium storage bottle 16 is connected with the capillary injection tube 18 through the needle valve 17, the capillary injection tube 18 is inserted into the cabin body 8, the needle valve 17 finely adjusts the flow of the working medium in the capillary injection tube 18, and the capillary injection tube 18 is used for injecting liquid drops and adjusting the diameter of the working medium liquid drops; the temperature measuring system consists of a hanging drop thermocouple 6, a data acquisition unit 13 connected with the hanging drop thermocouple 6 and an infrared camera 14 arranged outside the cylinder; the phase change observation system consists of a high-speed camera 15 arranged outside the cylinder; two side surfaces of the cylinder are provided with observation windows 10 which are respectively used for shooting by an infrared camera 14 and a high-speed camera 15.
The air conditioner 5 filled with liquid nitrogen is adopted to provide low-temperature cooling for the cabin body 8, the liquid nitrogen circulates in the low-temperature environment simulation system in an open mode and is discharged into the atmosphere through the second valve 1, equipment and pipeline arrangement of the low-temperature environment simulation system are simplified, cooling efficiency is improved, and liquid nitrogen loss is effectively reduced compared with the open type circulation without the air conditioner 5.
The cylindrical cabin body 8 and the coiled pipe 3 are made of copper so as to enhance the cooling effect of liquid nitrogen.
The liquid nitrogen conveying pipeline adopts a corrugated stainless steel hose, and a heat insulation layer is attached to the outside of the corrugated stainless steel hose so as to reduce the heat absorption of the liquid nitrogen in the conveying process.
The cabin cover 7 and the inner wall of the cabin body 8 of the cylinder are coated with aviation black paint to build a blackbody environment in the cabin body 8 of the cylinder.
The side glass of the observation window 10 opposite to the infrared camera 14 is made of infrared glass, so that errors of the infrared camera 14 in measuring the temperature change of the liquid drop are reduced.
According to the experimental method of the liquid drop radiation heat exchange experimental device, the air conditioner 5 is opened, the cooling temperature is set, the valve of the liquid nitrogen tank 4 and the first valve 12 and the second valve 1 are opened, the liquid nitrogen enters the gas mixing chamber in the air conditioner 5, enters the coiled pipe 3 for cooling the cabin body 8 after being processed, and the cylindrical cabin body 8 is cooled by utilizing the phase change heat absorption of the liquid nitrogen to form the low-temperature condition in the cylindrical cabin body 8; starting a vacuum pump 9, and starting a test when the temperature and the vacuum degree in the cabin 8 reach set values;
opening a needle valve 17, wherein the working medium flows through the needle valve 17 and a capillary injection tube 18 due to the pressure difference between a working medium storage bottle 16 and a cabin body 8 and then is mounted on a hanging drop thermocouple 6, a high-speed camera 15 records the size change and the phase change process of a liquid drop in the radiation heat transfer process, an infrared camera 14 measures the temperature change of the liquid drop in the radiation heat transfer process, meanwhile, the hanging drop thermocouple 6 also measures the temperature change of the liquid drop in the radiation heat transfer process, and transmits the acquired signal to a data acquisition unit 13 for processing; comparing the data measured by the infrared camera 14 and the hanging drop thermocouple 6 to ensure the accuracy of measurement; when the temperature change of the liquid drop needs to be finely measured, the observation window 10 is closed to make a cold black environment, and the temperature of the liquid drop is measured only by a hanging drop thermocouple.
Compared with the prior art, the invention has the following advantages:
1) the low-temperature environment simulation system can effectively reduce the temperature of the test cabin body and create a low-temperature environment, so that the heat radiation heat exchange characteristic of a single liquid drop under a vacuum low-temperature condition can be researched;
2) the high-speed camera is adopted, so that the size change and the phase change process of the liquid drops in the radiation heat transfer process can be recorded, and the evaporation and phase change phenomena in the radiation heat transfer process of the liquid drops can be intuitively understood;
3) the temperature of the liquid drop is measured by combining the hanging drop thermocouple and the infrared camera, and the measurement precision and reliability are high.
4) The needle valve is adopted to inject the liquid drops, so that the injection process of the liquid drops can be accurately controlled, and the liquid drops can be successfully hung on the hanging drop thermocouple.
Drawings
FIG. 1 is a schematic diagram of a droplet radiation heat exchange experimental device of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1, the experimental apparatus for liquid drop radiative heat exchange of the present invention comprises a low temperature environment simulation system, a vacuum maintaining system, a liquid drop carrying system, a temperature measuring system and a phase change observation system; the low-temperature environment simulation system is characterized in that the main body of the low-temperature environment simulation system is a cylinder and consists of a cabin cover 7 and a cabin body 8, the cabin body 8 is vacuumized, a coiled pipe 3 is laid on the outer wall of the cabin body 8, liquid nitrogen is contained in the coiled pipe 3 and serves as a coolant, and heat insulation cotton 2 wraps the cabin cover 7, the outer wall of the cabin body 8 and the periphery of the coiled pipe 3; the low-temperature environment simulation system also comprises an air conditioner 5 communicated with the coiled pipe 3, a first valve 12, a second valve 1 and a liquid nitrogen tank 4 which are connected with the air conditioner 5, wherein the liquid nitrogen tank 4 is used for being communicated with the coiled pipe 3; the vacuum maintaining system main body is composed of a vacuum pump 9, the vacuum pump 9 is connected with the cabin body 8 through a pipeline and is used for maintaining a vacuum environment in the cabin body 8; the liquid drop hanging system comprises a fixing support 11, a working medium storage bottle 16, a needle valve 17 and a capillary injection tube 18, wherein the fixing support 11 is arranged in a cabin body 8 and used for fixing a hanging drop thermocouple 6 and preventing the hanging drop thermocouple 6 from shaking to influence hanging drops, the working medium storage bottle 16 is connected with the capillary injection tube 18 through the needle valve 17, the capillary injection tube 18 is inserted into the cabin body 8, the needle valve 17 finely adjusts the flow of the working medium in the capillary injection tube 18, and the capillary injection tube 18 is used for injecting liquid drops and adjusting the diameter of the working medium liquid drops; the temperature measuring system consists of a hanging drop thermocouple 6, a data acquisition unit 13 connected with the hanging drop thermocouple 6 and an infrared camera 14 arranged outside the cylinder; the phase change observation system consists of a high-speed camera 15 arranged outside the cylinder; two side surfaces of the cylinder are provided with observation windows 10 which are respectively used for shooting by an infrared camera 14 and a high-speed camera 15.
According to the invention, the air conditioner 5 filled with liquid nitrogen is adopted to provide low-temperature cooling for the cabin body 8, the liquid nitrogen is in open circulation in the low-temperature environment simulation system and is discharged into the atmosphere through the second valve 1, the equipment and pipeline arrangement of the low-temperature environment simulation system are simplified, the cooling efficiency is improved, and the liquid nitrogen loss is effectively reduced compared with the open circulation without adding the air conditioner 5.
As the preferred embodiment of the invention, the cylindrical chamber body 8 and the coiled pipe 3 are made of copper, so as to enhance the cooling effect of liquid nitrogen.
As a preferred embodiment of the invention, the liquid nitrogen conveying pipeline adopts a corrugated stainless steel hose and is externally provided with an insulating layer so as to reduce the heat absorption of the liquid nitrogen in the conveying process.
As a preferred embodiment of the present invention, the inner walls of the cylindrical deck lid 7 and the cylindrical deck 8 are coated with an aircraft black paint to create a blackbody environment within the cylindrical deck 8.
As a preferred embodiment of the invention, the glass on the side of the observation window 10 opposite to the infrared camera 14 is made of infrared glass, so as to reduce the error of the infrared camera 14 in measuring the temperature change of the liquid drop.
As shown in fig. 1, in the experimental method of the droplet radiation heat exchange experimental apparatus according to the present invention, an air conditioner 5 is turned on, a cooling temperature is set, a valve of a liquid nitrogen tank 4 and a first valve 12 and a second valve 1 are turned on, liquid nitrogen enters a gas mixing chamber in the air conditioner 5, enters a coil pipe 3 for cooling a cabin 8 after being processed, and cools the cylindrical cabin 8 by utilizing phase change heat absorption of the liquid nitrogen to form a low temperature condition in the cylindrical cabin 8; starting a vacuum pump 9, and starting a test when the temperature and the vacuum degree in the cabin 8 reach set values;
opening a needle valve 17, wherein the working medium flows through the needle valve 17 and a capillary injection tube 18 due to the pressure difference between a working medium storage bottle 16 and a cabin body 8 and then is mounted on a hanging drop thermocouple 6, a high-speed camera 15 records the size change and the phase change process of a liquid drop in the radiation heat transfer process, an infrared camera 14 measures the temperature change of the liquid drop in the radiation heat transfer process, meanwhile, the hanging drop thermocouple 6 also measures the temperature change of the liquid drop in the radiation heat transfer process, and transmits the acquired signal to a data acquisition unit 13 for processing; comparing the data measured by the infrared camera 14 and the hanging drop thermocouple 6 to ensure the accuracy of measurement; when the temperature change of the liquid drop needs to be finely measured, the observation window 10 is closed to make a cold black environment, and the temperature of the liquid drop is measured only by a hanging drop thermocouple.