From the course: SOLIDWORKS: Designing a Stirling Engine

Introducing Stirling engines - SOLIDWORKS Tutorial

From the course: SOLIDWORKS: Designing a Stirling Engine

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Introducing Stirling engines

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- [Instructor] Before we actually start building the model, we're going to talk about Sterling engines. What they are, and very briefly how they work. You've probably heard of internal combustion engines. These are very common engines in the modern world. And typically you find them in things like cars, trucks, aircraft, power generators, all sorts of different applications. And what they have in common is that they burn fuel to create heat that gives a power output. Sterling engines also use heat to create an output, but they're different to typical car engines because they're actually external combustion engines. So whereas a car engine typically burns fuel within the cylinder internally, the Sterling engine actually burns fuel outside of the cylinder externally. Both types of engines use heat energy to make gases expand and power the engine. But in a car engine, these gases are removed by the exhaust and in a Sterling engine, these gases always remain sealed within the engine. And we'll explain a little bit more by looking at our model in a moment. Sterling engines have been around for a long time. They're named after a Scottish engineer called Robert Sterling, who came up with many of these ideas back in the early 19th century, over 200 years ago now. You might not have ever heard of these engines or even seen one working, and that's because they tend to be quite slow to react to changes in power, so they're not really useful with things like cars, but they're very quiet and they're very efficient, so they do have some specialists uses, things like powering small boats. This is the model that we're actually going to make. And we're going to use this to explain very simply how the engine works. Here on the right, we've got the flywheel, which is the power output. And as we turn this, you can see these two cylinders have pistons within them that move. The engine works on the principle of a change of temperature that causes gases to expand or contract. So we've got two sides, the hot side here, and the cold side here. Each side has got a piston within a sealed cylinder and both of the cylinders are joined by this tube. So within the engine, we've got a set amount of air that doesn't ever really change because it's sealed off from the atmosphere. For the engine to work, we have to apply a heat source on the hot side here. I mentioned before that this is usually applied via external combustion. And in our example, we'll have a small flame burner here, but you don't actually need to burn anything. You could also heat this via solar heating from the sun, hot water. I've even seen examples that just work from the heat of your hand. So let's pretend that we've just lit our flame burner and we've placed it underneath the hot cylinder here. As the cylinder heats up, the air inside the cylinder will also heat up and expand. And as it does, it will push this piston along here. The piston isn't a perfect seal within their cylinder. So as the air expands, it will also move along this tube and enter this cylinder. So now we have hot air in this cylinder, but there's no heat source because the flame is on this side and we have these cooling things. So this air will start to cool down. As it cools, it will shrink or contract, and it will drag this piston back in this direction. It will also push the air back down here to this side and it will start the process again. So the entire process will continue like this. This is quite a simple version of the Sterling engine and the scope of this course is really more about modeling this assembly and creating this virtual model. If you're planning to physically make this, I will give you some tips on the construction and getting everything working as we go through and at the end, but please be aware that a physical version of this will probably require quite a lot of tweaking and experimentation to get working well. So with that in mind, let's start producing our first parts.

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