James Watt

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This month's blog is about James Watt (1736 to 1819) the Scottish inventor and mechanical engineer whose work on the early steam engine ushered in the industrial revolution and laid the foundation for the study of thermodynamics.

James Watt started out his professional career as maker of mathematical instruments including parallel rulers, telescopes, barometers and such. While working on an astronomical instrument at the University of Glasgow his skills were so appreciated that in 1757, he was offered space to set up his workshop to repair the universities instruments.

Two years later, Watt started looking at the Newcomen steam engine, which was used to pump water from the coalmines throughout Scotland and England. The Newcomen steam engine consisted of a cylinder, piston, and balance beam with a counter weight. The steam was introduced into the base of the cylinder driving the piston. Once the piston was at the top of its stroke, a valve closed the steam flow, and another valve opened injecting cold water into the cylinder. The cold water created a vacuum within the cylinder causing the piston to retract. The piston was connected to a rocker beam and the other end of the rocker beam was connected to a rod pump that pumped out the mine.

The primary drawback of the Newcomen steam engine was the need to inject cold water into the cylinder to create the vacuum. The cold water caused the walls of the cylinder to cool down requiring additional steam injection to warm up the cylinder.

In 1763 Watt was asked to repair the University’s Newcomen steam engine. Although never having seen one before he was able to get it operating, but quickly determined that most of the steam being supplied to the engine was used to heat the cylinder after each cold water injection cycle.

By 1765 Watt determined that by condensing the steam in a separate chamber instead of the piston, and by keeping the cylinder temperature the same value as the inlet steam temperature, he realized that more energy from the steam could be converted to mechanical energy. The Watt steam engine still used saturated steam slightly above atmospheric pressure. The steam was injected into the cylinder at the bottom of the piston stroke to move the piston. On the Watt steam engine, a valve in the cylinder was opened once the piston reached the end of the stroke allowing steam to flow to a separate chamber. Water was then injected into the separate chamber to condense the steam. Later the condensing chamber was further improved by setting the condenser chamber in a cold-water tank, eliminating the need to inject cold water. Further improvements were made by collecting the warm condensate from the condenser and using it as boiler feed.

Watt further improved the design by sealing the top of the cylinder and injecting low-pressure steam into the top of the upper part of the cylinder to help move the piston down. This helped push the steam from the cylinder to the condenser chamber while increasing the speed of the engine. In 1775 these design improvement went into the first production version.

Like every good startup Watt needed a moneyman or “angel investor.” (The term “angel” was first used in 1978 by William Wetzel, a professor at that time at the University of New Hampshire.) Enter Matthew Boulton a serial entrepreneur that funded the Watt’s first steam engine. The new company Watt and Boulton got their original design completed and installed three engines in 1776. Their engines used 75% less fuel than the Newcomen engine due to its more efficient use of steam.

The early company made a practice of not selling the steam engines directly, instead they were given to the mine but the Watt and Boulton company charged a license fee to the engine owners based on their fuel savings over the Newcomen engine. As you can imagine many of the users of the Watt Boulton steam engines tried to stiff the company by not paying their full licensing. This resulted in multiple legal actions, making them both wealthy men.

Additional improvements to the Watt and Boulton engine occurred in later designs when the cylinders could be “precision bored” to minimize steam leakage. In addition an arrangement of steam inlet valves on the other side of the piston, allows the entrance of steam to both ends of the piston. This resulted in a double action engine, which in effect doubled the power output of the engine.

The next major improvement included the addition of epicycle sun and planet gears, and a flywheel to allow the output of the reciprocating engine to supply power to rotary loads. Now steam engines could replace water wheels and windmills in grain mills, textile mills, and other factories allowing the location of industrial plants anywhere instead of being required to be located next to streams and rivers. As an aside, Watt used the epicycle sun and plant gears to avoid paying licensing fees to the inventor of the crank. Once the patent for the crank ran out, the Watt and Boulton engines used the crank and flywheel design.

Watt continued to make improvements to the steam engine, including the flywheel governor to even out the load, and the Watt indicator to monitor the efficiency of his steam engine. Watt never stopped inventing. He developed the concept of horsepower and the SI unit of power, (the watt), was named after him. Watt pioneered the efficiency effort using improved design, among many of his great contributions.

I consider James Watt both and inventor, as well as the father of mechanical engineering. He took a rudimentary steam engine, gained an understanding of how it operated, and improved its efficiency 100 years prior to the study of thermodynamics. Not only did the Watt and Boulton steam engine do an excellent job of pumping out coalmines in England, but also its ability to bring power to any industrial process anywhere that required energy made the industrial revolution possible.

As you can see, just as today, in the 1700s there was cutting-edge technology, angle investors, patent disputes and legal action to enforce intellectual property rights. The more things change the more they stay the same.

Who do you consider as the father of engineering? Who would better represent the mechanical engineering field? Let me know by leaving a comment or sending me an email to blogger@eng-software.com. We are welcoming guest bloggers. Just send us a message if you would be interested in becoming a guest blogger.