Chapter 238： Ada's steam engine

During the autumn harvest in 1502, Marin had commissioned Da Vinci to develop a steam engine in the wheat field. At that time, Marin drew a schematic of the steam engine and handed it to Ada.

Now, more than a year has passed, and Marin remembers that the Tala lead-zinc mine is as deep as 50 meters and may need to be pumped. Therefore, Da Vinci's steam engine is very important.

In any case, mechanical pumping is always faster than people pumping, even the lowest-grade steam engine. In fact, the steam engine was used for pumping water in coal mines in the early 17th and early 18th centuries. There was no other use.

Until later, Watt improved the Newcomen steam engine, using a separate condenser and circulation system, reducing water consumption. Moreover, a crank gear transmission system of "sun and planet" was also developed to transform the reciprocating motion of the steam engine into rotary motion, laying the foundation for the steam engine to become a power machine ...

"Oh, no, I didn't draw the drawing of the" Sun and Planet "crank gear transmission system to Ada. No wonder he hasn't produced any results yet ..." Malin slaps his head in regret, remembering that he forgot to turn off the steam engine It is very important for Da Vinci to draw the transmission system that converts reciprocating motion into rotational motion.

No matter how smart Da Vinci was, he was just a man from the middle of the 15th century to the beginning of the 16th century. Because of the Holy See ’s ideological constraints, he did not dare to exchange advanced scientific knowledge with others. Some closed-door cars may not be able to come up with this transmission system.

At that time, because of the many things, Marin had to think about fighting against Denmark. The steam engine schematic diagram that he drew was the most original single-cylinder vertical steam engine. Moreover, only the steam engine cylinder part is drawn and the principle of piston movement is simply annotated. The rest is not involved. It is estimated that Ada is troubled.

Sure enough, when Marin rushed to Finch's laboratory, he saw a steam engine that was swaying up and down, and was running slowly up and down there. As for the crank gear transmission system, there is no such thing.

Da Vinci was frowning, thinking about how to make the steam engine run faster. Because, at the time, Marin told him that the machine should be turned and run at a fast speed.

This is also a question of Marin's understanding. In fact, in modern times, whether it is an electrical appliance or an internal combustion engine, the rotation speed is fast.

However, in the early days of steam engines, the speed of steam engines was very slow. The steam engine invented by Watt is much more efficient than the Newcomen steam engine, but the speed is only 40 to 50 revolutions per minute. In the modern era before Marin's crossing, an electric fan can turn 500 to 1500 revolutions per minute, which is completely incomparable. Even in the early 20th century, the steam engine speed reached 100 to 300 rpm. Therefore, it was Marin who demanded, not Da Vinci, who did not do well enough.

Next, Da Vinci explained to Marin in detail the structure and principle of the steam engine he made ...

The principle of this steam engine is very simple, that is, the bottom boiler, the steam is burning, going straight up. When the steam reaches a certain concentration and a certain air pressure is formed, it will break through a movable valve at the top, enter the cylinder above, and push the piston pressed at the bottom upward.

When the piston is pushed to a certain height, there will be an opening on the side of the cylinder to allow high-pressure steam to leak out. In this way, the air pressure in the cylinder was suddenly emptied. Under the action of gravity, the piston will fall back. At the same time, the valve between the boiler and the cylinder will also be closed.

When the piston falls together, the end of the piston that is similar to the balance bar will be driven by the piston to make a wooden rod at the other end move up and down. Of course, if there is a "sun and planet" crank gear transmission system invented by Watt, this connecting rod will not move up and down linearly, but will drive a wheel to rotate through the transmission system.

In addition, because the piston rises to the top, there will be an opening to release the steam. The water vapor is formed by the vaporization of water. Therefore, the water in the boiler also decreases with the release of steam. If the water is not added, the boiler may be dried and then explode.

Therefore, Da Vinci designed a water supply system on the bottom side of the cylinder. There is also a movable valve in the pipeline of this water supply system. Moreover, the water container of the water supply system is set higher and has a certain water pressure. When the pressure in the cylinder is high, the valve of the water supply system is closed. However, when the piston rose to the highest level and the steam in the cylinder was suddenly released, the pressure of the cylinder Li dropped sharply. At this time, the water pressure of the water supply system exceeds the air pressure of the cylinder. Then, when the valve is loose, a small amount of water will be ejected into the cylinder, and then it will be pressed into the boiler by the piston.

After listening to the introduction of the whole structure, Marin found that-what a special feature is a Newcomen steam engine ...

Although, this design is indeed ingenious. However, there is a problem, that is to add water to the boiler, in fact it can not be added on top. Because the steam in the boiler is formed by the water surface. Adding water from above will inevitably lower the temperature of the surface of the water layer in the boiler and affect the generation of steam.

Therefore, Marin remembers that the steam circulation system of later generations is generally placed at the lower side of the boiler to add water to the boiler. In this way, the temperature of the uppermost layer of water in the boiler will not be lowered, and the generation of large amounts of water vapor will not be affected.

The disadvantage of the Newcommen steam engine is that adding water from above will lower the temperature of the surface hot water and reduce the generation of steam. In this way, the steam volume of the steam engine is affected, and the power and operating speed are reduced.

The later addition of water from the side not only avoids the problem of lowering the surface water temperature. Moreover, by adding cold water below, it is closer to the combustion chamber and can be heated more quickly.

"Yeah, the steam circulation system ..." Malin slapped his head, remembering where the steam engine's shortcomings were.

Watt's transformation of the Newcomen steam engine, the most important thing is two points-the first is to add the "sun and planet" crank gear transmission system, so that the operation of the steam engine, from reciprocating motion, into practical rotation; , A water circulation system with a separate condenser was added.

When the water vapor at the upper end of the steam engine leaks out, it is not directly discharged into the air, but through a pipe into a condenser surrounded by cold water. In order to increase the cooling contact area, the pipes immersed in the condenser water are generally designed to be curved to enhance the condensation effect of the condenser. Moreover, the water in the condenser is changed frequently. Once it is hot, it will be replaced with cold water. Moreover, the demand for condensate water is not high. Any water can be used, and seawater can also be used. Unlike water in boilers, clean fresh water is generally used to prevent scaling from affecting efficiency.

After the water vapor condenses into water in the condenser, it will pass through a pipe and connect to the bottom of the boiler side. The cooled water will be sent into the boiler to form a cycle. In this way, the water in the boiler is basically not much consumed. And the boiler does not need to add water from outside frequently. After all, by adding water from the outside, it is easy to let the hot boiler cool down and affect the efficiency of the steam engine.

However, it does not mean that with this condensing circulation system, there is no need to add water. Because, the piston of the cylinder is not 100% sealed. When doing work, a small amount of steam will also escape from the gap between the cylinder and the piston.

Therefore, even with a condensation circulation system. After a period of time, the boiler still needs to add water from the outside once. Just like the old green-skinned train, when it came to the station, it often needed to add water. The boiler water must be added, as is the cooling water.

Therefore, in order to ensure the safety of the boiler and not to explode, the side wall of the boiler will generally use high temperature resistant glass or other instruments to display the water level in the boiler. Once the water level in the boiler has been reduced to a dangerous level, in order to prevent an explosion, it is necessary to temporarily stop and fill the water in the boiler.

Marin told Da Vinci two important improvements to the Watt steam engine that the physics teacher gave to him in junior high school, and he was stupid. Then the old man sighed in heaven:

"The old man always thought he was the smartest person in the world, but I didn't expect that the guy named Watt was even better than the old man ..." said Da Vinci's eyes. Obviously, this product was hit.

Marin chuckled and said to Da Vinci:

"Well, Ada, don't be discouraged. Everyone has their own specialty. That watt, that is, the steam engine is better than you. You are better than painting, you are better than him!"

Listening to Marin's words ~ www.novelhall.com ~ Da Vinci, the hard hit, was better off. Then, according to Marin's ideas, the steam engine was "watted" ...

However, Marin clearly remembers that there is also a centrifugal governor on the Watt steam engine, which is used to control the speed of the steam engine to be stable.

However, the junior high school physics teacher of Marin did not talk about this principle, so Marin did not understand. After all, he didn't graduate from the Department of Mechanics, just a pretty liberal arts student in physics.

As a result, the speed of the steam engine may be somewhat unstable. But for him, the steam engine requirements are not high, and the speed is not stable.

But in line with the principle of "can do the best", Marin briefly explained the principle of the centrifugal governor to Da Vinci, which is probably a cone pendulum connected to a steam valve to control the speed of steam output ... , Marin left this problem to Da Vinci ... Well, the superior, you must learn to throw the problem to the subjects ... If you do everything, Zhuge Liang will definitely die after overwork ...

When the Watt-type steam engine comes out, it is easy to pump water. At that time, Marin took out the Archimedes screw and turned it into a screw pump to pump the groundwater of the Tala lead-zinc mine. Do n’t be too practical ...