[james watt]
James Watt
Thomas Seville in 1698, Thomas Newcomen in 17 12 and james watt in 1769 made early industrial steam engines, all of which made their own contributions to the development of steam engines. In 2008+0807, robert fulton was the first to successfully use a steam engine to drive a ship. Watt was not the inventor of the steam engine, but in his. The steam engine, the newcomen steam engine, has been around for a long time, but it consumes a lot of coal and is inefficient. Watt gradually discovered the defects of this steam engine by using scientific theory. From 1765 to 1790, he made a series of inventions, such as separate condenser, cylinder external insulation layer, piston lubricated with oil, planetary gear, parallel motion connecting rod mechanism, centrifugal governor and so on.
From the end of 16 to the end of 17, the British mining industry, especially coal mines, has developed to a considerable scale, and it is difficult to meet the requirements of pumping groundwater only by manpower and animal power, and there are abundant and cheap coal as fuel on site. The need of reality urges many people in Britain, such as Papan, Savili and newcomen, to devote themselves to the exploration and experiment of "lifting water with fire".
The original vacuum steam engine was used to pump water from mines. Newcomen's steam engine introduced steam into the cylinder, then closed the valve and injected cold water into the cylinder. When steam condenses, a vacuum is created. The air pressure on the other side of the piston pushes the piston. A pole that goes deep into the mine is connected to drive the water pump. The motion of the piston of the steam engine is transmitted to the piston of the pump through this rod, and the water is pumped out of the well.
The first big improvement is to separate the cylinder from the condensing cylinder through the valve. Watt invented this improvement in Birmingham. This improvement has improved the efficiency of the steam engine. The next improvement is the automatic operation of the valve.
These early vacuum steam engines were inefficient, but safer, because their pressure was relatively low, and the machine shrank inward in case of material damage. Their efficiency is not outward explosion, but is limited by external air pressure, cylinder deformation, combustion boiling efficiency and condensation capacity. The theoretical maximum efficiency is limited by the relatively low boiling temperature of water at ordinary atmospheric pressure. The use of high temperature and high pressure steam greatly improves the efficiency of steam engines. However, this kind of steam engine is much more dangerous than vacuum steam engine. The explosion of boilers and machines caused many serious accidents. The safety valve has brought great improvement here. When the pressure is too high, the safety valve deflates and depressurizes. But the only way to really ensure safety is to rely on it.
Savery made the world's first practical steam pump, and obtained the British patent named "Friends of Miners" at 1698. He first filled an egg-shaped container with steam, then closed the steam inlet valve and sprayed cold water outside the container to condense the steam in the container to form a vacuum. When the inlet valve is opened, the water at the bottom of the mine is sucked into the container by atmospheric pressure through the inlet pipe. Close the water inlet valve, reopen the steam inlet valve, and use the steam pressure to press out the water in the container through the drain valve. When the water in the container is drained and filled with steam, close the steam inlet valve and drain valve, and spray water again to condense the steam. In this way, the two egg-shaped containers work alternately and continuously drain water.
Savery's water pump is pumped by vacuum suction, and the pumping depth cannot exceed six meters. In order to pump water from a mine tens of meters deep, it is necessary to install a water pump deep in the mine and use high steam pressure to pump water to the ground, which is undoubtedly difficult and dangerous at that time.
Newcomen and his assistant Cali invented the atmospheric steam engine in 1705, which is called newcomen atmospheric steam engine. This kind of steam engine was first popularized in Britain, then in continental Europe, and its modified products were still being manufactured until the beginning of19th century. The thermal efficiency of the atmospheric steam engine in newcomen is very low, mainly because the steam enters the cylinder and condenses on the cylinder wall which has just been cooled by water, thus losing a lot of heat.
[steam engine locomotive]
Steam engine locomotive
1764, British instrument repairman james watt noticed this shortcoming when repairing newcomen steam engine model for Glasgow University, and invented a steam engine with condenser separated from cylinder wall in 1765, and obtained a British patent in 1769. The original Watt steam engine still used the balance bar and pull rod mechanism to drive the water pump. In order to extract condensate and air from the condenser, watt.
Watt's creative work made the steam engine develop rapidly. He turned the machine that can only carry water into a widely used steam engine, which doubled the thermal efficiency and greatly reduced the coal consumption. Therefore, Watt is a reformer of steam engine.
Since the late18th century, steam engines have been widely used not only in mining, but also in smelting, textile, machinery manufacturing and other industries. It has increased the textile output in Britain by five times (from 1766 to 1789) in more than 20 years, provided a large number of consumer goods for the market, accelerated the accumulation of funds and put forward urgent requirements for the transportation industry.
The experiment of using steam engine as propulsion power on ships began in 1776. After continuous improvement, Fulton, USA made the first practical open-wheel propulsion steam engine ship "clermont". Since then, steam engines have been used as propulsion power on ships for more than one hundred years.
/kloc-in 0/800, Trevithick of England designed a high-pressure steam engine, which can be installed on a larger car body. 1803, he used it to propel a motorcycle running on a circular track, and found people who like novelty to ride and charge them. This is the prototype of the locomotive. Stephenson, from Britain, constantly improved the locomotive and built a "rocket" in 1829.
At the end of 19, with the rise of electric power application, steam engine was once the main power machine of power station. During the period of 1900, there was a steam engine power station in new york, USA, with a single power of 5 MW.
The development of steam engines reached its peak in the early 20th century. It has the advantages of constant torque, variable speed, reversibility, reliable operation and convenient manufacture and maintenance, so it is widely used in power stations, factories, locomotives and ships, especially warships.
It is important to note that many textbooks (history books and physics books) say that Watt was the inventor of the steam engine. This is misinformation. The steam engine was independently invented by Zavelli and Newin in 1698 and 1705, respectively, for pumping water in mines. The efficiency at that time was very low. The steam engine was greatly improved, the condenser was separated from the cylinder, and the crankshaft, gear transmission and centrifugal governor were invented, which modernized the steam engine and greatly improved its efficiency. Watt's invention is still used in modern steam engines, and the unit name of power is named after his surname to commemorate Watt's contribution.