Kai Fu Han

Chapter 38 Ondol
The heated Kang used by the Jurchens in Liaodong is composed of "stove-flue-chimney", with the heated Kang above the flue.

Lin Xinqi plans to make two types of heated beds. One is a heated Kang that contains a stove, which can be used for cooking and the high-temperature smoke generated to heat the heated Kang.The other type does not include a stove. A fire furnace is built directly in the middle of the kang on the outside. Fire is burned inside, and the high-temperature smoke generated heats the kang.

The former is suitable for large rooms with sufficient space. The fire is burned inside the room and the chimney is set outside the room; the latter is suitable for rooms with small space. The furnace mouth is set outside the room and the chimney is also set outside the room.

Liu Xinqi built a simple model on the open space using scrap wooden boards and wooden strips left over from making tables and chairs, so that the structure of the Ondol was clearly displayed in front of Liu Zhimu.

"Then what material is this flue made of?" Liu Zhimu asked.

"Adobe bricks are then covered with a layer of mud mixed with broken straw, which can seal in smoke and resist fire." Liu Xinqi replied.

"Where's the upper part of the flue?" Liu Zhimu asked.

"Because the upper part of the flue has to bear load, it is sealed with refractory bricks, and then a layer of mud is applied on top to make a whole flat surface. Finally, a layer of kang boards is laid on the flat surface, and straw mats and quilts are laid on the kang boards." Liu Xinqi replied.

"What is a kang board?" Liu Zhimu asked.

"Use four long wooden strips to form a rectangular frame on the flat ground, place a few thin wooden sticks staggered, and fill it with mud mixed with broken straws. After drying, remove the frame to become a kang board. Smaller, a kang that is nine feet long (2.97 meters) long and six feet wide (1.98 meters) is composed of three kang boards that are six feet long (1.98 meters) long and three feet wide (0.99 meters), or smaller. Liu Xinqi explained to Liu Zhimu while demonstrating on the ground with wooden sticks.

"I probably understand, but making this kang board will be very time-consuming because it needs to be dried." Liu Zhimu asked another question.

"The time-consuming kang boards are made in advance, and more are made at a time. All the young people in the clan are doing the kang board in the past few days, and all the horses and carts are involved in transporting soil, kang boards, adobe bricks and other materials." Liu Xinqi replied.

"The bricks are definitely not enough, there is too much difference." Liu Zhimu said.

"Use adobe bricks wherever possible. Only when sealing the flue, use fire bricks or small stone slabs. I have a quick method for making adobe bricks. You don't need to dry them in the sun, and you don't have to worry about running out of adobe bricks."

Next, Liu Xinqi demonstrated to Liu Zhimu how to quickly make adobe bricks.

First make a rectangular iron container with four sides sealed and two empty ends at the top and bottom. The plane of the container is the same size as the adobe brick and the height is one and a half the height of the adobe brick.

Make a movable device at the bottom of the container with a flat surface on top and a connecting rod on the bottom. The size of the flat surface is basically the same as the bottom of the container and can move up and down in the container.

On the top of the container, also make a device with a plane below and a connecting rod on the top, and then connect the lowermost part of the bottom device rod and the uppermost part of the top device with iron rods on the outside of the container, and all connection points use movable shafts.

Finally, add a long horizontal rod to the uppermost part of the top device as a lever.

Fix the entire container so that the height of the container from the ground is the same as the height of the connecting rod of the bottom device.

When in use, first lift up the long rod, the connecting rod drives the bottom device upwards, and the upper device also upwards, forming a container that is closed on all sides, the bottom is also closed, and the upper part is open; Moist soil is poured into the container.Then press the long rod down hard, the top device closes the upper part of the container downwards, and continues to squeeze the soil in the container downwards. Because the bottom device is close to the ground, it is blocked by the bottom surface before it comes out of the container, so it will be done. A space enclosed on six sides.

The long pole uses the principle of leverage to amplify the force of pressing down several times or more than ten times, so that dense adobe bricks can be quickly made.

After the earth bricks are pressed, lift up the long rod, and the long rod drives the bottom device upward to push the prepared earth bricks out of the container.

After Liu Xinqi explained and demonstrated the principle and structure of the adobe brick maker to Liu Zhimu, Liu Zhimu thought for a while and was astonished.

"It's amazing that such a simple structure can make adobe bricks quickly." Liu Zhimu sighed: "I just have a question, why does this long pole amplify the downward force? Did you cast a magic spell?" Listen After hearing Liu Zhimu's words, Liu Xinqi couldn't help but burst into laughter.

"Hahahaha, there's no magic in this." Liu Xinqi found a long piece of wood and placed a square piece of wood under a quarter of the wood. He raised the long side and let the short side fall to the ground, signaling Liu Zhimu. : "You stand on the wood and I'll show you."

Liu Zhimu stood up and saw Liu Xinqi holding the end of the long end with one hand and gently pressing down, Liu Zhimu was lifted up.

"Oh, so that's the case. I used to use Dao when I was doing carpentry work. I didn't expect such a magical truth to be contained in it." Liu Zhimu suddenly realized.

"I will talk about these principles in the physics class in the future. You craftsmen, don't relax in your studies while you are working." Liu Xinqi said: "To learn from things, everything has its own laws. We are here In future work, we must be good at discovering, summarizing, and utilizing these patterns."

"This is also the difference between us and animals. For example, why does the sun rise in the east and set in the west? Why does the sun rise and set at different times in spring, summer, autumn and winter? Why does the moon look different every day in a month? Why do the tides rise and fall? etc. Wait." Liu Xinqi finally said to everyone present: "Even if you don't know why, as long as you know these laws and make good use of them, they will become our 'inexhaustible' wealth."

"Yeah." Zhou Xinyuan, who had just walked into the courtyard, heard Liu Xinqi's words beside him, touched his beard, and nodded secretly.

……

I was busy until the next day, October 28, at the end of the hour (11 o'clock), when I finally made the first heated ondol, using ready-made adobe bricks, fired bricks and stone slabs.

The quick adobe brick maker is still being made at the blacksmith, and it will have to wait until tomorrow, as the mud bricks have not yet dried.

However, in the process of making the first heated ondol, all the participating masons finally understood the principles and methods of making this heated ondol. During the exploration process, they also made some improvements that Liu Xinqi had not considered.

such as:

After the adobe of the heated kang is built, a layer of mud or white lime is applied. This will make the entire kang form a complete enclosed space, which can not only keep warm but also prevent smoke leakage.

When building the kang, first pad it with soil and sand on the ground to half the height of the kang, then compact it firmly, and then use adobe to build the flue.

After building the flue, fill the other spaces other than the flue with soil and sand, so that the earthen kang surface can be better carried and the kang surface will not break or sink.

Several larger spaces are made in the flue, with the bottom lower than the bottom of the flue, which can be used to store soot, called "ash chambers".This will prevent soot deposits from clogging the flue after it has been used for too long.

The flue is designed with a slope such that one end of the fire pit is low and one end of the chimney is high, making the smoke exhaust smoother.And it is bent into an "S" shape under the kang board, which increases the contact area between high-temperature flue gas and the kang surface and enhances the utilization of the residual temperature of the flue gas.

wait….

Some craftsmen have proposed more detailed, beautiful and easy-to-use structures and improvements. Liu Xinqi has not adopted them for the time being, but he also explained to the craftsmen: "At present, our most important thing is to quickly provide this kind of heated kang for all tribesmen. You have already tried it. After lighting the fire, the kang board is very warm, and it will definitely be very comfortable to lie on it in winter, so speed is the first priority at the moment. As for the more beautiful and convenient transformation later, you can leave it behind for others to make money on the kang. Money is being used."

"Can you still make money from this?" Liu Zhimu asked.

"Of course you can make money. Anyone who sees this heated kang will want to install one for their own home. Then our craftsmen can make the kang for a fee. Those who give it to the poor will earn less, and those who give it to the rich will make it as beautiful as possible. , atmosphere, etc., collect more money when the time comes.”

(End of this chapter)