Being able to pop a little pod into your coffee machine and get out a freshly brewed cup of coffee is one of the most used inventions of our time. So, how do these magical devices create the perfect cup of joe on demand?
One of the biggest things that single serving coffee makers brought to the industry was ease of use. It used to be that you had to have coffee ground, then measure it out, get a coffee filter, pour water and brew. That isn’t arguably an arduous task, but it still took time in your groggy morning mood. Pod coffee makers have brought a variety of flavors into our morning routines all with a few pushes of a button.
The first thing that needs to happen in a single serving coffee maker is for the user to fill up the reservoir in the back. Following this, simply pop a pod in and press brew Here’s where the engineering and magic begins. That wurrrrrrrr noise you hear when your coffee maker starts is actually a little pump that starts pushing water through the machine. In most cases, this pump consists of a small motor with an uneven roller on it. This uneven roller will cause a flexible tube to move in a pumping action, sucking water through. However, many coffee makers won’t use a pump, in fact, some coffee makers have no moving parts. Rather they use what is called a check valve – a valve that only allows flow in one direction. Water flows through the check valve due to gravity to the heater. The heater heats the water, creating a difference in temperature between the heated water and the reservoir. This differential causes flow from the reservoir to the heater, and the check valve keeps the water moving in one direction. This principle allows many coffee makers to operate with only tubing and a heater, no moving parts.You can learn more about this principle in the video below.
The heating element is the next step in the process. Oftentimes coffee makers will use coiled copper tubing that gets heated. This increases the surface area of the water in contact with the heated metal and speeds up the process. Some coffee makers will use heated reservoirs, but by far the most common are coiled heated tubing. The heat is created through electrical resistance. A current tries to flow through the metal which presents significant resistance to the flow of energy. These heaters are typically 1500 watts and will bring your coffee to 185 degrees Fahrenheit This resistance transforms the electrical energy into heat energy, bringing your coffee water up to temperature.
Now, your coffee water has been pumped to the top of the coffee machine. At the end of the tube, there is a narrowing, like a hose nozzle, that increases the pressure of the water. This high pressure water is pumped in and throughout the pod, only to exit through the small hole poked in the bottom of the pod when you popped it into the machine. This pressurization of the water ensures that the whole pod’s flavor gets used and the water makes it all the way through the coffee capsule. If you wanted to dissect a single serving coffee pod, you would see that the coffee actually rests on a final layer of filter paper that keeps your coffee from being full of grounds. The final step in the process is to fill up that mug and for you to enjoy.
One thing you may not expect to be in your single serving coffee maker is an air compressor. That final blast of steam you see come out of your machine is actually a burst from the air compressor used to clear out the pipes. This keeps your machine clean after every use and ensure the perfect brew every time.
Sources: Explain that Stuff