Tue. Nov 30th, 2021

This isn’t an oil derrick, this is one of the world’s first engines ever invented. This one machine is the genesis of a family tree of modern technology: airplanes, power plants, trains, cars, and even refrigerators. They all owe their invention to this innovation, the Newcomen steam engine. Thomas Newcomen, born in Devon, England in 1664, was an ironmonger and a preacher who was determined to find a way to solve the problem of flooding in the local mines. It turns out, the Newcomen steam engine is not only the direct ancestor of modern engines, but its invention in 1712 helped set the stage for the machines that powered the industrial revolution. Had this machine not been designed, the entire resulting tree of technology, our society as we know it, could have evolved differently and our world be unrecognizable.

So, let’s explore this ancestor to all engines and see how it works. The Newcomen steam engine resembles an oil derrick, and that’s because it has a similar function. Oil derricks pump oil up from the ground, and the Newcomen steam engine was used to pump water out of mines. Let’s see this engine in action…  it seems slow, doesn’t it? But this was the first engine of its kind, so moving at the speed of 12 cycles a minute was rather fast. Let’s take a look!  Over here we have the steam engine, while on the opposite side is the pump that went deep into the mines. Above that is a heavy wooden beam and a fulcrum which make a seesaw like action with arch-heads and chains which transfer motion from the steam engine side to the pump side.

These pump and see-saw movements were not new, but rather what was revolutionary was the steam engine, so let’s focus on that. Here we have a piston, a cylinder, a tank of boiling water with a fire underneath it, a tank of water, and a set of valves. To start the cycle, the weight of the pump side is heavier, so the piston is pulled up.  While this is happening, hot steam is filling the cylinder, and when the chamber is full, the chamber is sealed by closing these two valves. Next, the valve which connects to the water is quickly opened and a spray of water cools the steam, and then the valve shuts.

This cooling causes the steam to turn from a gas back into a liquid, that is, it condenses and as a result, the amount of pressure pushing from the inside of the cylinder drops dramatically thereby creating a vacuum. With the pressure from the atmosphere above the piston and a vacuum below, the piston is pushed down and power is produced. The motion is then transferred through the balance beam and used at the pump side to move water out of the mines. This part of the cycle is named the power stroke. Now that the piston is down, the cycle resets and these two valves open.

The vacuum is broken, and steam rushes back in, while the condensed liquid water exits out the side and the cycle repeats. The weight of the pump side lifts the piston while the chamber refills with steam. When the piston reaches the top, the steam and output valves close, the water valve briefly opens, and a spray of water condenses the steam back into liquid thus creating a vacuum again. The piston is pulled down, the two valves open, the vacuum breaks, steam enters, and liquid leaves out the side. Now the weight from the other side pulls the piston back up, and steam fills the cylinder.

Wait wait hold on…- before we get stuck in a loop, let’s pause this cycle and look closely at the cylinder of steam to better understand how it creates enough force to move this massive wooden beam and pump water. To do this we’re going to zoom in so we can see the molecules bouncing around. At the bottom we have the cylinder of steam, in the middle is the piston, and above that is the air in the atmosphere. Both the steam and air particles are bouncing around and every time a molecule bounces on the piston it imparts a little bit of force.  The force of air particles bouncing over the area of the piston is called pressure, and because the atmosphere is imparting a force over that area, we call it atmospheric pressure. 

So, in this step of the cycle, we have the piston at the top with the cylinder full of steam, right before the valve with the cool water spray is opened. The two pressures from the bouncing of the atmosphere’s molecules and the bouncing of the steam’s molecules equal each other. Now when water is introduced to the steam, the water cools down the steam and with that it slows down the speed of the steam molecules. As the steam slows down, eventually inter-molecular bonds begin to form between gaseous water molecules or in simpler terms, the steam turns from a gas into a liquid.

This liquid then forms droplets, falls to the bottom of the cylinder and collects at the bottom. However, now you can see an imbalance of forces. The atmosphere is still pushing down on the piston, but now that the steam has condensed into a liquid, there isn’t much force bouncing up from the underside of the piston. This lack of force holding up the piston, means that the piston is pushed down by the atmospheric pressure above the piston and this lack of pressure is called vacuum pressure. Tho, technically this is a partial vacuum, because the cylinder wasn’t fully empty of steam, but regardless this imbalance between atmospheric pressure and the vacuum is where the force to move the piston and pump is generated.

In addition, this is why Newcomen’s engine is called an atmospheric engine. It uses the atmosphere to drive it on the power stroke, and the maximum steam pressure in the cylinder never significantly surpasses atmospheric pressure. The steam engines we are familiar with use high pressure steam, sometimes hundreds of times atmospheric pressure, but in the early 1700s, vessels that could withstand high pressure were unreliable and deadly explosions were possible. Ok, let’s move on, so now that we understand  the concept of creating a vacuum, let me ask you this: if I were to take 1 liter of liquid water, and boil all of it, turning it into steam, what size volume would that steam take up, considering it’s at atmospheric pressure and not compressed.

Maybe it would take up 10 liters of space?  Maybe 100 liters? Well, the volume from one liter of liquid water, boiled into steam, would take up almost 1,700 liters of space. That is a crazy amount of expansion. Here’s a 2-liter bottle of water. let’s boil all of it, and without pressurizing the steam, it will fill a much larger space in fact, four large refrigerators. Now let’s reverse the process. Let’s start with a massive 425-liter cylinder of steam at atmospheric pressure, like we do with the Newcomen Engine now, let’s cool it down, and the gas turns into slightly more than a cup of liquid water.

You can see that from a lot of steam bouncing around. When condensed we get just a fraction of that volume in liquid water. Thomas Newcomen understood this concept and had the metal working know how to apply it in order to build this engine to pump water. This innovation was revolutionary, and it kicked off a completely new tree of technology. While the idea of metal working and boiling water with fire had been around since antiquity. And in the 16th and 17th centuries the understanding of vacuums and pistons had improved, Newcomen’s idea of combining fire, steam, pistons, and vacuums in a cyclical engine to do continuous work was groundbreaking.

The Watt steam engine invented 60 years later, evolved in efficiency and became the real workhorse of the industrial revolution. But James Watt got his ideas while working on the Newcomen steam engine!  In the 1800’s evolved designs of high-pressure steam engines powered boats and locomotives. And eventually steam was replaced with the internal combustion engine. But none of those engines would exist without the founding work of Thomas Newcomen. His ability to engineer and creatively combine the technologies around him changed the world forever.

By Ahsan