Question

Differentiate between James Watt's steam engine and Thomas Newcomen's steam engine?

Answer 1

Answer:

Both the Newcomen and Watt steam engjnes were atmospheric engines. They both used steam to fill the cylinder under the piston so that the pump shaft weight could pull the piston upwards.

In both engines the steam was then condensed by spraying cold water at the steam. This created a vacuum and atmospheric air pressure then forced the piston back down, pulling the pump rod upwards and pumping water from the mine.

The difference is how condensing the steam was achieved.

in the Newcomen engine, water was sprayed directly into the steam cylinder to condense the steam. This meant that the cylinder itself was heated and cooled continuously and it wasted a lot of steam heating the cylinder before it would stay as steam on every stroke of the engine.

in the Watt engine, the cylinder was opened to a separate chamber by a pipe and cold water was sprayed into that chamber for quenching. That allowed the working cylinder to stay hot so no steam was wasted reheating the cylinder on each stroke.

This increased the efficiency of Watt engine by a factor of three or four.