Hand rubbing nuclear fusion live in the wilderness

Chapter 341 The Strange Rolling Heat Dissipation Method

Manufacturing the 'Zero' series of satellites does not require many new technologies.

Things like lanthanum-gallium-silicon solar thin-film power generation panels and lithium-sulfur batteries are all technologies that have been developed and manufactured a long time ago.

A little more troublesome is the customization of functional chips.

Under the current situation, Won cannot miniaturize the computer and install it on the satellite for the time being, and can only make a fixed response by integrating functional chips.

In this way, there are quite a few functions that need to be integrated into the chips placed on the zero satellite, such as simple calculation functions, judgment functions, instruction execution functions, and data storage functions.

These correspond to satellite altitude checks, orbit adjustments, signal reception and return, etc.

Without these, the satellite in the sky will cut through the sky and become a bright meteor in less than ten days.

Maybe it will hit the Korean won on the top of his own head.

160 kilometers of low-Earth orbit is still too close.

This is just the minimum requirement for a satellite to orbit.

Ordinary situations in which humans are launched into space do not fly close to the surface.

For example, it is extremely rare that the berthing orbit of the late mission of the Apollo spacecraft in the United States is as low as 5000 meters. In more cases, the effective orbit height starts at least [-] kilometers.

There are also slightly lower ones, such as military spy satellites, weather satellites, and space stations that require high-definition shooting.

These are all operating in the lowest orbit, but they are actually at an altitude of more than [-] kilometers.

Because the lower the orbit, the closer it is to the ground, the greater the air resistance encountered by the satellite/space station, and the greater the impact of gravity.

In this way, more fuel is required to maintain the orbital altitude and speed of the satellite, which greatly reduces the service life of the satellite.

Satellites operating at different orbital altitudes have different speeds at maintaining circular orbits.

At an altitude of 160 kilometers, a speed of 7.9km/s is required to counteract the influence of the earth's gravity.

But if the orbit is raised to an altitude of 7.62 kilometers, then only a speed of [-]km/s is needed to offset the influence of gravity.

Further up, the required speed is even lower.

This can be calculated by the formula, that is, GmM/(r^2) (the gravity of the earth on the satellite) = mv^2/r (the centrifugal force of the satellite's motion).

If you simplify it, you can first change it to [GM/r=v^2], and then simplify it again and write it as [v=√(GM/r)].

Even a person who has only attended elementary school can see from the simplified formula that the linear velocity of satellite motion is inversely proportional to the square of its orbital altitude.

That is, the greater the height of the track, the smaller the required linear velocity of motion.

If it is pulled to a geosynchronous orbit of 3.6 kilometers, the speed of the satellite even only needs 3.1 kilometers per second to maintain a stable orbital motion.

This speed is much lower than the first cosmic speed.

The manufacture of a communication satellite is not difficult for South Korean won.

In the case that many parts can be directly exchanged through technology points, plus the assistance of CNC machine tools.

In one afternoon + one night, he has almost finished nearly one-third of the parts.

A little more troublesome is the manufacture of the long-wave signal antenna, which took nearly six hours to manufacture.

It's not about shape or anything.

It is the material used to make long-wave antennas on satellites.

In the early days of carrying satellites, the signal antennas were generally very long and large due to material problems in order to receive enough signals.

However, the space of space shuttles or launch vehicles has certain limitations, and antenna groups with a length and width of several meters cannot be accommodated.

But this thing is very important and necessary, so it can only be made of memory metal.

The advantage of using memory metal to make the satellite antenna group is that it can be folded into a small volume after being formed first.

After being transported to low-earth orbit, because the conditions of low-earth orbit meet the manufacturing conditions, the signal antenna will slowly return to its original appearance.

Greatly reduces the space occupancy rate.

The disadvantage is that the processing steps of the low-temperature one-way shape memory recovery metal are relatively complicated.

Even if Won has the corresponding knowledge information in his mind, complicated processing steps are unavoidable.

Because common nickel-titanium-based shape memory alloys, copper-based shape-memory alloys, and iron-based shape-memory alloys all have their own 'transformation temperature'.

This 'transition temperature' is determined by the physical properties of the metal and cannot be changed.

After thinking about it for three seconds, Won decided to use nickel-titanium-based shape memory metal to make the antenna on the satellite.

The manufacture of this kind of memory metal is simpler than copper-based and iron-based memory metals, and it takes much less time.

The manufacturing method is to carry out proportioning and smelting the alloy according to a certain ratio of nickel-titanium materials.

After the alloy is smelted, it is shaped, and then heated at a high temperature until it reaches the 'martensitic state temperature'. At this temperature, a large amount of deformation is carried out near the Ms memory point, and the deformation degree exceeds [-]%.

Each deformation needs to be heated at high temperature to restore the prototype, and this process can be repeated continuously.

The principle is that the deformation of the NiTi memory alloy in the 'martensitic state' exceeds the 'martensitic plateau area', and then a certain degree of irreversible plastic deformation and a certain dislocation structure are produced.

After reheating, the reversible part of the martensitic deformation works first, allowing a partial recovery of the shape.

After cooling, the dislocation structure will generate a force field similar to spring force, which drives the metal material to deform and return to its original shape.

This is the principle why the memory metal can restore its original shape at the 'transformation temperature'.

And repeated heating, deformation, and cooling can greatly increase this memory effect.

If the technology is good and the recovery conditions are suitable, the memory metal parts made will be fully restored in just half a minute after being crumpled.

From six o'clock in the evening to one o'clock in the morning, Han Yuan finally made the signal antenna on the satellite.

The final product has the feeling of the aluminum tube antenna on the roof of the 90s TV set with bamboo poles.

The front section is an X shape composed of four hollow memory alloys, followed by six shorter vertical signal quotation marks sticks.

The guide stick has a certain arc, which can increase the radio signal sent by the ground to the greatest extent.

Seeing the antenna in this shape, some older viewers in the live broadcast room immediately missed it.

[This is the antenna used on the satellite?Similar to the one I use on my old TV. 】

[I really miss it. When I was a child, I used to hold a bamboo pole and look for signals everywhere in order to watch TV. 】

[Anchor, why don't you get a signal pot?That's much better. 】

[Can this thing really receive electrical signals? 】

[Speaking of the signal pot, I remembered the one installed in my house before, it was very big, but it could search some adult channels——]

[So awesome?Ask for a link! 】

[Ask for a link to a certain treasure, I will place an order now]

[Asia-Pacific No. 6! 】

[Satellite Pot is a thing that looks for channels. It often happens that the channels you want to search cannot be found, and when it rains, it is easy to find no channels. It is a scam. 】

[My family uses a satellite pot. With this kind of pot, I can receive overseas signals, and foreign programs are delicious. 】

[Good guy, receiving an overseas signal, this is a punishment. 】

[Open the door upstairs to check the gas and water meters. 】

[Open the door, the courier has arrived. 】

[Ah, yes, yes, yes, foreign programs are delicious, so get out of here quickly. 】

The audience in the live broadcast room were very interested in the antenna made by Korean Won, which aroused the memories of many people.

Han Yuan glanced at the barrage, and felt a little nostalgic. Whether it was the signal pot or the signal tower in his hand, he had used it when he was a child.

I even ran to the roof of the building to clear the snow for the signal pot in order to watch TV when I was so cold in heavy snow.

However, nostalgia did not affect his subsequent movements. After the antenna tower was completed, he kneaded it into a ball easily.

This is one of the tests for memory metal, but the method is a bit rough.

Seeing this scene, there was a burst of question marks in the live broadcast room. This time, before Han Yuan had time to answer, the audience in the live broadcast room pretended to be b.

[It's just memory metal, what a fuss! 】

[It will be restored immediately, like a magic trick. 】

Seeing the barrage on the virtual screen, Han Yuan smiled weirdly, didn't speak, just stood there holding the crumpled signal antenna.

30 seconds passed, 1 minute passed, and 2 minutes passed. The group of signal towers in his hand remained unchanged, and some viewers became impatient.

【? ? ? 】

[Didn't it say that it can be recovered?There is no change at all. 】

【That's it?That's it?Is this memory metal? 】

[Anchor, have you rubbed too much, it can't change back to its original appearance. 】

[Time, how long has it been?Even if it can be recovered, it will take time. 】

[Time shit, pretend to understand if you don’t understand!The recovery of the memory metal needs to be placed in its 'transformation temperature'. 】

[It’s heating, I’ve seen a spring made of memory metal, it can be restored by heating after straightening, but the anchor’s this should not be heating. 】

[I remember that the deformation temperature of nickel-titanium memory metal seems to be 40 degrees. 】

[Suddenly thought, if you use memory metal to build a car, you won't be afraid of car accidents, right?It can also recover by itself if it is hit. 】

[The company that bought the light and sent the car has a car made of memory metal, which is worth more than [-] million yuan. However, if there is a car accident, it may be like this: "The car is deflated, people are gone, pour hot water, and the car is fine." Alright, people are buried'_]

【Crash into a car, the person is dead, the car is fine, please ask the next driver! (dog head)]

[Sounds awesome, if I break it, can it stick back by itself?If it can't be broken, can it be restored if I tie a knot in it? 】

I have to say that sand sculpture netizens sometimes have big brains.

Some questions made Han Yuan completely confused.

Create a memory metal wire, if it is tied with a dead knot, can it return to its original shape?
This is a question worth experimenting with.

As for the reason why the signal antenna in his hand did not return to its original shape, it was indeed related to its 'abnormal temperature'.

The "nickel-titanium-based shape memory alloy" in hand has a deformation recovery temperature close to 150 degrees, instead of [-] degrees for ordinary memory metals.

The reason why it is designed so high is to take into account the space environment.

In low-Earth orbit, which is more than 160 kilometers above the ground, the atmosphere is quite thin.

When the satellite is operating at this altitude, because there is no atmospheric buffer, the temperature on the side facing the sun can reach more than [-] degrees.

On the side facing away from the sun, the temperature can be as low as minus [-] degrees.

The issue of temperature control needs to be considered whether it is for unmanned satellites, deep space probes, or manned space stations and spacecraft.

If it is manned spaceflight, it is necessary to ensure that the temperature inside the space shuttle or space station is stable.

Take the space station launched by Huaguo as an example.

During the space station's 60-kilometer low-Earth orbit flight, the temperature outside the cabin on the sunny side will exceed [-] degrees, while the temperature on the back side will be as low as minus [-] degrees Celsius.

The heat dissipation of satellites, space shuttles, including large space stations is a very troublesome thing.

In addition to the thick insulation layer, other means of heat dissipation are definitely required.

In space, heat dissipation basically relies on radiation heat dissipation to solve the problem of residual heat that cannot be solved by the insulation layer.

That is, a circulating pipe, which is filled with coolant liquid, and then the pipe connects the parts that generate heat and the heat dissipation part.

Finally, an electric pump is used to circulate the liquid in the tube, and the cold liquid runs to the place where heat is generated to accumulate heat. After the heat storage is completed, it goes to the cool place to dissipate heat.

But in this way, just a complete heat dissipation system will add a lot of extra weight to the space station or satellite, which greatly increases the burden.

The satellite launched this time did not design a heat dissipation system.

But it doesn't mean he didn't consider this issue.

He would paint the parts of the satellite with the exception of the solar panels with a white paint he picked up from his rudimentary knowledge of aerospace applications.

This white paint has a higher absorptivity than aluminum, but a higher emissivity.

There is no convection in a vacuum, and the overall heat exchange with the outside world is basically carried out by heat radiation.

On the one hand, the surface of the material absorbs thermal radiation, and at the same time releases heat to the radiation in the external vacuum.

And this white paint has a high emissivity and can control the temperature on the surface of the satellite to about 110 degrees.

Although this temperature still has some damage to electronic components, it still needs to be lowered.

While lowering the temperature again, Won still did not design a cooling system.

Let's use another way to dissipate heat.

This mode is called 'satellite roll cooling'.

Just like the barbecue sold on the street.

The principle is actually very simple. After the satellite goes into the sky, it will start the internal control program to avoid excessive temperature on one side by rolling slowly.

Because there is no atmosphere, the temperature formed by thermal radiation will be quickly emitted into the icy vacuum by the white paint when it rolls to the dark side, effectively reducing the temperature of the satellite's surface.

The combination of the two is enough to deal with heat radiation.

The advantage is that there is no need to design an additional heat dissipation system for the satellite.

The disadvantage is that the attitude and angle of the satellite roll need to be strictly planned, which requires high technical requirements.

Moreover, the white paint can only be used on the main part of the satellite, and cannot be applied to the power generation board.

But that's enough for the Korean won.

The temperature of the main body is reduced without affecting the internal electronic components.

As for the solar panels, that requires no treatment at all.

The lanthanum-gallium-silicon solar-emitting point material with special structure can withstand the temperature of [-] degrees after molding.

A temperature of more than 200 degrees is nothing at all, even if it is doubled, it will have no effect on power generation.

If it is not too troublesome, South Korea can also design a layer of thermal power generation board under the power generation board.

The kind that generates electricity through thermal effects can also harvest an additional amount of electricity.

However, the efficiency of lanthanum gallium silicon thin-film solar power generation panels is enough for satellites, and there is no problem even if a tiny electric propulsion engine is driven 24 hours a day.

(End of this chapter)