Chapter 551: Methods to Solve Vacuum Heat Dissipation Problems
Following Weng Yunzong, the two came to a conference room.
The large screen came down, and a relevant design drawing was projected on it.
This is the design drawing of the ‘aerospace engine’ developed by the Institute of Aeronautics and Astronautics on the electromagnetic propulsion system.
Xu Chuan took the control pen from Weng Yunzong and carefully read the design drawings on the screen.
One picture after another passed through my eyes. Judging from the design drawings, the aerospace engine designed by the Aerospace Research Institute looked very much like the word "屮".
The long and narrow pipe in the middle is composed of an electromagnetic acceleration field and a compressed gas chamber made of improved superconductor materials. It is shaped like a cone without a tip connected to a long and narrow cylinder.
The long and narrow accelerating field is composed of internal magnetic coils, magnetic poles, discharge chambers, propellant delivery pipes, anode and yang gas distribution chambers and other structures.
Its main purpose is to electrolyze the air working fluid absorbed by the compressed gas chamber into plasma, and then increase the speed through a strong magnetic spiral acceleration field, thereby providing huge thrust to the engine.
The compressed gas chamber is located at the top of the long and narrow cylinder. Through a special absorption device, it can absorb a large amount of air and provide it, remove other suspended matter, dust and other impurities in the air, and provide pure air working fluid to the acceleration field.
These two parts are the middle area of the character "屮", which is designed to run through the fuselage of the space shuttle, from the nose to the tail, providing the main power for the space shuttle.
The other two shorter pipes are small propulsion devices deployed on the wings of the space shuttle. They are similar to the main engines, but their active role is to perform auxiliary power adjustment, steering, etc.
Judging from the design drawings, researchers from the Aerospace Research Institute have considered all aspects of the work.
Of course, this released design drawing is not all the details, nor can it be all the details.
After all, there cannot be only a few dozen design drawings for an aerospace engine, and adding two zeros is not enough.
The early aerospace engine design drawings were really drawn by trucks. Not to mention other things, the F119 engine used on the F22/F35 alone has tens of thousands of parts, which is enough to show the complexity of the aerospace engine.
The level is simply not something that ordinary enterprises or even the country can play around with.
In fact, the total number of countries in the world that have the ability to independently design aerospace engines is probably in the double digits.
.......
After briefly but carefully looking through the design drawings of the aerospace engine, Xu Chuan thought about it with interest, looked up at Weng Yunzong, and said:
"I don't know much about the details and design of aerospace engines, but I have a few questions to ask."
"Academician Xu, please tell me."
"The first question is, have you considered the shielding of the magnetic field?" After thinking for a while, Xu Chuan asked: "During the operation of this aerospace engine, whether it is an improved superconductor or a related permanent magnet structure,
All will produce extremely large magnetic fields, which will have an impact on some precision instruments and many related equipment on the space shuttle, as well as personnel."
"Especially from the design drawings, the engine you designed is almost large enough to cover the bottom layer of the entire aerospace engine. In this way, its impact will be even greater."
Weng Yunzong nodded and replied: "I have considered it."
After a pause, he continued: "As for the magnetic field shielding of aerospace engines, it is mainly carried out through two methods: magnetic shielding layer and metal shielding efficiency."
"In the design of the aerospace engine, the entire engine system is located on the bottom layer of the space shuttle. It will be separated from the miniaturized controllable nuclear fusion reactor and fuel chamber in the middle layer, and the personnel carrying space in the upper layer. The separation layer will use extremely efficient
The shielding material is made into a protective cover to avoid mutual influence.”
"Although this will increase the weight of the space shuttle a lot, there is currently no other way to perfectly solve the impact of the magnetic field."
"After all, you also know very well how strong the magnetic field formed by the improved superconductor material is."
Xu Chuan nodded and said: "Well, what about these shielding magnetic fields and the heat dissipation of the space shuttle itself? Is the thermal radiation method sufficient?"
Hearing this question, the average person may think that it is not easy to dissipate heat in outer space. It is a vacuum of minus 270 degrees outside. In such cold conditions, isn't it easy to dissipate heat?
But in fact it really isn't.
Junior high school textbooks tell us that there are three main modes of heat transfer: thermal conduction, thermal convection and thermal radiation.
Compared with these three heat transfer methods, heat conduction and heat convection usually have higher heat transfer efficiency, while thermal radiation efficiency is lower and the heat dissipation process is slower.
For example, the double-layer vacuum thermos cup or thermos bottle used in daily life, when filling with hot water, is equivalent to cutting off the heat dissipation of the hot water through heat conduction (of course, the actual situation still cannot achieve complete isolation), so the insulation time becomes longer.
Very long.
Under normal circumstances, space can be regarded as a vacuum environment. In this environment, there are no conventional materials such as air, soil, water, etc. as conductors, so energy cannot be exchanged with the outside world through heat conduction and heat convection, and can only be achieved through thermal radiation.
However, the speed of heat radiation dissipation is very slow and the efficiency is very low.
The interaction between the magnetic field and the shielding material, and when the space shuttle is operating, will generate a large amount of heat. If this heat is not transferred out, it will greatly affect the safety of the space shuttle.
Therefore, heat dissipation is a major issue in the space shuttle.
Hearing this routine question, Weng Yunzong didn't think much about it. He just thought that this person might not know much about aerospace. He nodded and said:
"Heat dissipation must be considered in aerospace. Considering that the speed of thermal radiation is slow, and there are a large number of equipment in the space shuttle that continuously generate heat, the current approach is to add a large number of heat sinks to the outside.
Radiating energy thereby cooling the equipment."
"At the same time, referring to the configuration of the space station and the American space shuttle, the heat is transferred through the coolant circulation system."
Xu Chuan shook his head and said: "With conventional thermal radiation cooling methods, I think it may be difficult to solve the problem of heat transfer and dissipation of the magnetic field shielding layer and the space shuttle itself."
"If the heat production value of a conventional space station and a space shuttle is one, then for a space shuttle that uses a miniaturized controllable nuclear fusion reactor, the heat production value may not be less than ten."
"Whether it's the heat generated during the cooling of the external field coil or the heat from the magnetic shielding, I'm afraid it's not that easy to solve."
Hearing this, Weng Yunzong frowned.
For vacuum heat dissipation, apart from improving the specific surface area of materials and transformation methods, there are currently no other good methods for radiation.
The frequency of blackbody radiation (complete thermal radiation) is only related to temperature, and different materials only affect the reflection and refraction of electromagnetic waves by objects. In general, the frequency of radiation is only related to temperature.
The International Space Station is a similar solution, using stack area to solve the radiation heat dissipation solution.
And the key is that the temperature of the heat sink cannot be raised too high. After all, the greater the temperature difference between the two heat reservoirs of the refrigerator, the lower the efficiency of the refrigerator, so in fact the temperature of the heat sink will not be much higher than the temperature of the heat source.
If the heat sink cannot solve this problem, you will be in big trouble.
The Aerospace Research Institute had considered the problem Xu Chuan mentioned, but it did not expect that this approach would be far from sufficient.
After thinking for a while, Weng Yunzong looked up at Xu Chuan, frowned and said: "If this is the case, in addition to improving the specific surface area of the material and the transformation method, and improving the thermal radiation efficiency, there is only an increase in the weight of the working medium.
The evaporation phase change is carried out to dissipate heat.”
"But in this case, increasing the working fluid will increase the weight of the spaceflight. Overall, some of the gains will outweigh the losses."
The weight of the space shuttle cannot be increased at will. The thrust of the space engine is the main limitation.
Moreover, every increase in weight requires not only an increase in engine thrust, but also an additional amount of fuel or working fluid.
In this way, the additional fuel and working fluid take up another weight.
Just like the Saturn 5, the most powerful launch vehicle system in history developed by the United States, its first-stage rocket has a total thrust of up to 3,400 tons, but in fact it can only send up to 100 tons of materials into low-Earth orbit.
The remaining 3,300 tons of thrust are all used to consume its own weight.
Therefore, every change in the weight and design of the space shuttle has a huge impact.
More importantly, they still don't know how much thrust the aerospace engine has.
Although in theory, the aerospace engine that uses improved superconducting materials and spiral orbits to increase the length of the acceleration field can achieve a thrust of hundreds of KN, the actual amount will only be known after the first test.
.
In this case, every additional heat-dissipating working fluid increases the thrust requirement of the engine, and the condition requirements become extremely stringent.
After thinking about it, Weng Yunzong looked at Xu Chuan and asked tentatively: "Academician Xu, do you have any ideas?"
Although he raised the question, he honestly didn't think this person had any good ideas about aerospace heat dissipation.
After all, crossing industries is like crossing borders. The field of aerospace and the field of controllable nuclear fusion are two completely different fields. It is just a casual question to ask tentatively.
Moreover, heat dissipation of spacecraft in the vacuum environment of outer space is a huge problem that the world is grappling with.
Those of a global nature that have the ability to push satellites or space stations into space will have to face this huge trouble.
But what he didn't expect was that the man unexpectedly nodded and said that he really had a solution.
Glancing in surprise, Weng Yunzong said curiously: "How do you say that?"
Xu Chuan smiled, picked up the control pen on the table, and flipped the aerospace engine design diagram on the screen to the structure.
"I made some rough calculations before. If we use the current thermal radiation efficiency to dissipate heat from a space shuttle that combines aerospace engines and miniaturized controllable nuclear fusion technology, at least two surface areas of the space shuttle heat sink are needed."
"But this is obviously unrealistic. It is impossible for us to carry so many radiators to the sky."
"Then finding a new way to dissipate heat is necessary."
"And considering the special vacuum environment in space, apart from thermal radiation, there are not many methods that can be used."
"What you just mentioned is that evaporative phase change heat dissipation by increasing the weight of a part of the working fluid is a feasible method, but it will lead to an increase in the weight of the space shuttle, which will have a greater impact on all aspects."
"But to solve the heat dissipation problem, we still have to rely on the heat dissipation fluid..."
Hearing this, Weng Yunzong had some doubts in his eyes, and looked at Xu Chuan with some confusion. He wanted to use the working medium to dissipate heat, but he didn't want to increase the weight of the spacecraft. How to do this?
Noticing his eyes, Xu Chuan smiled, pointed to the aerospace engine design drawing on the screen and continued: "So I need you to modify the design of the aerospace engine and add a set of evaporators at these two positions.
Phase change heat dissipation device.”
Looking along the location pointed by Xu Chuan, Weng Yunzong's eyes fell on the pipeline between the aerospace refrigerant storage and the acceleration field.
After staring at the design drawing for a while, his pupils suddenly shrank, he couldn't help but swallow, took a deep breath and said: "You mean, we are going to use the original aerospace working fluid to solve the heat dissipation problem.
?”
Xu Chuan smiled and nodded, saying: "That's right."
"Additional addition of cooling fluid will not only compress the space on the space shuttle, but also cause a huge burden on the space shuttle and aerospace engine."
"But unlike the traditional Hall propulsion unit and space station equipment, the aerospace engine uses the working fluid to ionize it. It performs additional acceleration through the magnetic field and does not care what the state of the working fluid is.
"
"In this case, we can transfer the circulating heat inside the space shuttle through the coolant circulation system by storing the liquid ultra-low temperature working fluid in advance, release it on the aerospace working fluid, and then transfer it to the aerospace engine
, and then go to outer space.”
On the side, Weng Yunzong's eyes became brighter and more admiring. He followed Xu Chuan's words and continued: "Furthermore, the working fluid at ultra-low temperature is preheated before entering the acceleration field, which can also reduce some of the air pressure.
The consumption of electrical energy by the engine..."
Xu Chuan smiled and shook his head: "This part of the savings is not a big deal. The key point is that this method can solve the internal heat of the space shuttle."
"Theoretically, this method is possible, but how much heat can be transferred and consumed by the aerospace working fluid actually requires you to conduct specific experiments."
After a pause, he added: "And you not only need to conduct experiments and test data, you also need to test which conventional aerospace fluid can remove more heat."
Weng Yunzong nodded quickly and said: "This is no problem. We don't need to wait for the aerospace engine to be manufactured for this kind of experiment. We can do it now."
Although the experiment of simulating the space environment to test the heat carrying capacity of the working fluid has high requirements on the experimental environment.
But this is the top Xinghai Research Institute in the country, and it is easy to create an ultra-low temperature vacuum environment.
Xu Chuan smiled and said, "Then I'll leave it to you."