After taking a turn underground, Tianxuan saw that the Mayans were working hard, without stopping at all, and he couldn't help but feel a sense of admiration in his heart, and sighed: "Mr. Bell, you really forget to sleep and eat every day for work!" ”

"It's not!" Bell said.

"Huh? So what is everyone working so hard for now? Tianxuan asked with a wink.

"Now there will be a big military operation in the glacier layer, and the soldiers and horses will go first before the grain and grass are moved, and these will be transported to the Labor City!" Bell explained.

"I see! No wonder it's so busy! As he was talking, Tianxuan suddenly remembered that he seemed to have said that he was going to the glacier layer when he was separated from Hercules, and suddenly asked Bell with wide eyes: "Mr. Bell, I heard Hercules say that he seems to be going to the place called Labor City in the glacier layer." Why don't you send supplies there? ”

"Oh? It seems that you know this, and these materials are indeed going to be delivered to Labor City. Bell was shocked that Tianxuan also knew about this, but immediately returned to normal.

"How far is that?" Tianxuan tilted his head slightly and asked.

"It's only a few thousand kilometers!"

"What? Thousands of kilometers? It's farther than the Twilight City! Tianxuan's eyes widened and he said.

"It's not too far away. The farthest reaches into the core layer. Bell moved his lips slightly and said calmly.

“Oh，MyGod！ Is it possible to convey such a long distance? Tianxuan's eyebrows shrugged, his eyes were round, and he couldn't believe his ears.

Bell looked at Tianxuan's particularly surprised expression and smiled faintly: "You heard it right!" The distance to the Labor City is indeed not far! ”

"Huh! What an eye-opener for me again! Can you show me how this line works? Tianxuan squeezed his brows and made a sincere request.

Bell smiled, patted Tianxuan's shoulder and said, "No problem! Then, he waved his hand at Tianxuan and said, "Come with me!" ”

So, Tianxuan followed behind Bell......

First, they came to the spherical sac that was loaded with supplies. Bell pointed to the spherical sac and said, "When the supplies are in there, what we need is to extract the air inside. With that, Bell closed the spherical capsule and connected an air pump to the outside of the sphere to pump air.

When he finished pumping, Tengen saw Bell disconnect the pump from the ball and press a button on the sphere. Then I listened to the sound of "eating" from inside the ball.

"What's that sound?" Tianxuan asked, pointing to the sphere.

"The sound of airbags bulging!" Bell stepped forward and tapped his finger on the ball and explained, "In order to damage the material in the event of a collision during transportation, the air inside the ball was first extracted, and then the airbags around it were released to clamp them firmly together. ”

"Oh! I see! This is similar to how Speedpost on the ground transports fragile items. Tianxuan muttered to himself when he heard this.

When the spherical sac was operated, Tianxuan tried to roll the ball to the mouth of the material pipe like a leather ball, then turned his head and said with a smile: "Don't say it, this thing can be pushed up by anyone." And it doesn't feel heavy! ”

Bell smiled and continued, "Now you can push the sphere forward. ”

So, Tianxuan followed Bell's words and prepared to push the sphere forward. However, at this time, he found that the inside of the pipe was closed, so after pushing the nine spheres, he asked, "Mr. Bell, I just found out that the inside of the pipe is closed, what is going on at this time?" ”

At this time, Bell took Tianxuan to the operation room, then turned on the hologram and said, "Now I will drain the air in this section of the pipe and let it be in a vacuum." With that, Bell slid his finger across the operation screen a few times, and then saw a blue light flashing on the top of the pipe not far away.

"The test is complete, there is no fault, now start the vacuum operation!" When the blue light appears, the artificial intelligence on the console sends out a prompt.

After a few minutes, the AI reminded again: "Confirm the destination." ”

"Labor City!" Bell gave instructions to the console.

"Confirmed, open the interior hatch!"

As soon as the artificial intelligence's voice fell, Tianxuan heard the sound of the "gurgling" sphere rolling in the pipe.

"Close the hatch and start the critical flow rate."

"Critical flow velocity?" Tianxuan was puzzled when he heard this term, so he turned his head and asked Bell, "Mr. Bell, what is the critical flow velocity?" ”

"Oh! This critical flow rate can be called the economic flow rate. It means that under a certain water flow rate or solid movement conditions, the flow rate at the bottom of the pipe where the solid moves or the layer shifts. ”

Tianxuan scratched the back of his head and said, "I still don't understand!" ”

"Hmm!" Bell touched his chin with his finger and thought for a moment, then explained, "Then I'll tell you the simplest slurry pipe!" ”

"Okay!" Tianxuan blinked a few times, then stood straight and listened.

Bell then cleared his throat and said, "The slurry is a solid-liquid two-phase flow, and the flow of this fluid in the pipe is in many ways different from the flow of a homogeneous liquid. The change of the concentration of solids in the upper and lower layers of the heterogeneous fluid on the cross-section is very obvious, and the suspended solid particles are strongly affected by the inertial force. ”

"Oh! In that case, I have a little idea. Tianxuan nodded and said.

"That's good!" Bell explains, "I'm going to talk about the principle of transportation -- for heterogeneous fluids, as the average flow velocity of the pipe decreases, the solid particles change more and more significantly until a fixed or sliding bed surface appears at the bottom of the pipe at a certain flow rate. The critical flow velocity at this time is called the siltation velocity. The flow rate at this time symbolizes the lower limit of safe operation, and a lower flow rate will lead to the formation of a solid particle bed in the tube, and the friction loss will increase accordingly. If the flow slows down sufficiently, it will lead to a blockage of the pipes. ”

Seeing that Tianxuan still didn't seem to understand, Bell slid his finger on the screen a few more times, and a hologram immediately appeared in the air.

"This is? ......" Tianxuan asked, pointing to the image.

"This is how the inside of the slurry pipe works! You'll understand it if you take a closer look! Bell said.

"Oh!" So, Tian Xuankai carefully observed the image, and saw that in the slurry pipe, as soon as the water flowed through, countless solid particles were suspended everywhere in the pipe, but some were washed away with the water flow, and some were attached to the pipe wall and gradually accumulated.

"After that, the pipeline will be clogged!" Tianxuan pointed to the accumulation under the wall of the tube in the image.

"Hmmm! You're right, so we need to increase the flow rate so that all these accumulated solid particles are suspended and follow the flow. With that, Bell manipulated the screen again.

Immediately after, Tianxuan saw that the speed of the water flow in the pipe was increasing, and soon, the solid particles accumulated under the pipe wall gradually suspended again, flowing with the water flow. After a while, there was no accumulation at the bottom.

"Oh!" Tianxuan touched his chin, puffed out his cheeks and said with a smile: "Now I understand!" The critical flow velocity is the minimum speed at which the loss of friction and gravity is overcome, and the pressure loss in the transmission power and pipeline is minimized without particle precipitation. ”

Speaking of this, Tianxuan looked at Bell directly, a smug smile appeared at the corner of his mouth, and said: "And the meaning of economic flow rate is also simple, if the actual flow rate in the slurry is less than this speed, siltation will occur at the bottom of the pipe, which will affect the normal operation; If the actual flow rate is much higher than this threshold, it is a waste of resources. So the critical flow rate that happens to be reached is the most economical flow rate, right? ”

Bell smiled and nodded in agreement.

Then, Tianxuan continued to ask: "Mr. Nabel, now that I understand this slurry process, you can tell me in detail about the material pipeline in front of you!" ”

"Of course! This material pipeline uses the energy of the air flow to blow the sphere for movement. Bell said.

"Airflow?" Tianxuan's eyes widened and he said.

"What's the problem?"

"Huh!" Tianxuan lowered his head, leaned his fingers slightly on his lips and said, "It's nothing, it's just that we also have air flow pipes on the ground." ”

"Huh? Tell me about the situation on the ground. There was a curious glint in Bell's eyes.

"Well, our airflow on the ground is mainly used to transport minerals, cement, fly ash and other solid waste. However, it is generally limited to solid particles. Tianxuan said as he recalled the scene on the ground.

"Hey! At this level, you can only go so far! Bell sighed a little disappointed after listening to Tianxuan's introduction, thinking that he could get some valuable information.

"Oh!" Tianxuan suddenly remembered something and shouted again, "I remembered, in the conveying process, physical operations such as heating, cooling, drying, and airflow classification can also be carried out at the same time, or some chemical operations. ”

"Oh! I know! Bell replied with a grim look.

Tianxuan was a little uncomfortable with Bell's reaction, so he asked, "Mr. Bell, what do you think?" ”

Bell shook his head slightly, sighed and said, "But that's it. Take a look at our pneumatic conveying! ”

He then turns on the hologram to narrate.

First of all, the picture that switched to was a spherical sac at rest in the pipe, only to see a gust of air flow blowing, dozens of spheres as if a domino effect had occurred, rolling one after another, and there was almost no kinetic energy attenuation, what made Tianxuan even more puzzled was that the air flow did not seem to be strong.

THE FACT IS INDEED AS TIANXUAN FELT, AND IT WAS CONFIRMED BY BELL'S MOUTH THAT THE AIR VELOCITY WAS ONLY 5-8M/S

"How is that possible?" Tianxuan shook his head and couldn't believe what he heard, and couldn't help but shout, "The airflow velocity of the solid particles on our ground must also reach at least 18~30m/s, such a large capsule, even if it is a ball, it is impossible!" ”

"Of course it can be done!" Bell pointed to the hologram and said calmly, "You forgot that this is in a vacuum!" ”

"In a vacuum?" Tianxuan suddenly understood something.

"That's right, a substance in a vacuum, whether light or heavy, can be suspended as long as the net force is zero, and it has no tendency to move. As long as the force is applied, even if it is small, it will move in the opposite direction of the force because there is no air resistance in the vacuum. Bell explained slowly.

"So......" Tianxuan said.

"So, it doesn't take much effort to send the sphere to a great distance." Bell continued.

"But I still don't understand!" Tianxuan said with a frown.

"It's okay, just ask!" Bell responded with a smile.

"That said, what if you climb a hill or have a turn or a vertical situation? It's still going to be affected by gravity! ”

Bell smiled again and switched the hologram to another frame, only to see a row of track-like devices sticking to the outer wall of a vertically rising pipe on the screen, constantly flashing blue light.

“What？ What are these add-ons for? Tianxuan asked.

Bell explains: "This is used to create an electromagnetic force to counteract gravity, so that during this vertical ascent, there is no force at all, and the sphere automatically levitates and then blows up with a gentle blow." ”

"Hahaha! So that's it! I understand! As he spoke, Tianxuan stretched out two thumbs up and praised Bell.

At this time, Bell became a little proud, held his head high and said with some disdain: "It's not that I deliberately belittle, it's just that the design on the ground is too bad." Let the solid particles be scattered in the pipe, and it is easy to appear in the sedimentary layer in the pipe at some dead ends, and the cross-section of the runner is reduced. ”

"Huh!" Tianxuan responded.

Bell paused and said: "What's more terrible is that in the vertical pipeline for upward pneumatic transportation, when the gas speed is reduced to a certain critical value, the air flow can no longer evenly disperse the dense particles, and will converge into a plunger shape, the phenomenon of surge occurs, and the pressure drop rises sharply." It doesn't take long for the inside of the pipe to be cleaned or it will fail. ”

"Huh!" At this time, Tianxuan didn't know what to say, but just grabbed the back of his head.

And just like that, after Bell was gushing for a while, Tianxuan began to return to the surface with him in a depressed mood......

Reading the first book of the novel