Famous mathematician Hero, also known as Heron was probably the first one to come with a simple steam engine. Hero from Alexandria, also wrote three books on mechanics and properties of air. This dates back to AD. 75.
Hero’s engine consisted of a hollow sphere, free to rotate about an axis with bent tubes coming out from either sides. This sphere was filled with water and mounted over fire. Due to the heat from the fire, water would get vaporized, coming out with force from the two bent tubes on the side. As a result of this steam powered propulsion, the sphere rotated.
Hero was the first who theorized the use of steam in the second half of the first century. Learning to harness energy from steam took a long time. Though the Hero’s engine, Aeolipile was invented in the first century, it took more than 1600 years to develop the first actually working steam engine. This engine was used for draining water from mines and gardens. The age of steam which started after that, powered the industrial revolution. Steam played an important part in transforming the global shipping industry and revolutionizing modern warfare.
In 1606, Giovanni Battista della Porta of Naples formulated theories about creating vacuum using steam. His theory suggested that when water is converted into steam inside a closed container, the pressure inside the container increases. Porta argued that on similar lines, if steam condenses inside a closed container, as a result, pressure will go down resulting in the formation of vacuum. This discovery by Porta played a crucial role in many future developments.
This theory put forward by Della Porta was brought into reality in 1679 by French scientist and mathematician, Denis Papin. Denis Papin came up with ‘Digester or Engine for Softening Bones’ which is a forerunner of today’s pressure cookers and autoclaves. This device was nothing but a sealed cooking pot which used steam to cook food. This device was also equipped with a safety valve to avoid higher than safe pressure.
Savery’s Mainer’s Friend
England faced a timber crisis in the late 17th century. Shipbuilding and use as firewood were the major applications which consumed large amounts of wood. For shipbuilding, there was no substitute available for wood, but coal could substitute the firewood. Water seeping into the mines restricted the mine digging activity thus limiting the coal production. There was an urgent need for some device which could pump the water out of the mines.
In 1698, a military engineer Thomas Savery secured a patent for a pump operated using steam. This pump, named ‘Miner’s Friend’ was designed to pump the water out of the mines. The model consisted of a boiling chamber. A pipe with a non-return valve descended into the water that needed to be removed. Cold water was poured over the steam chamber which resulted in condensation of steam inside the chamber. This vacuum drew up the water from below. A non-return valve was used to ensure that the sucked water did not fall back. Unfortunately, the engine, could not become successful as it had many limitations.
Firstly, it was able to lift water to a maximum height of 10 meters. This required installing multiple pumps to lift the water to larger heights, which was practically not feasible. The heating and cooling of the chamber was done manually, making it quite difficult to operate the pump. As a result, this machine was sold mostly to private estates for draining the excess water and circulating it in the gardens.
In 1712, Thomas Newcomen, a blacksmith came up with The Newcomen Engine, by combining Savery’s Miner’s Friend and Papin’s steam driven piston. Newcomen fixed a piston to the steam chamber in Savery’s engine and this piston, when pulled by the vacuum, activated a piston which again filled the chamber with steam. This mechanism eliminated the use of horse operated pump as in case of Savery’s engine. As a result, the cost of operation came down substantially. Due to these advantages offered, Newcomen Engine was used in hundreds of mines.
Watt noticed the problems with above designs and rectified them by adding a separator condenser. Further changes and innovation lead to a successful steam engine.