Heat engines are machines that change heat energy into motion or work. They follow certain rules known as the laws of thermodynamics. Here’s how a heat engine works, broken down into simple steps:

1. Getting Heat: First, heat engines take in thermal energy (this is like warmth) from a hot source. This hot source can have temperatures between 400 K and 1500 K.

2. Making Work: Next, some of that heat energy is turned into work. According to the first law of thermodynamics, if we look at the internal energy change, it can be summarized like this:

   • Change in internal energy = Heat in - Work out

3. Releasing Heat: The leftover heat that isn't used for work is sent out to a cooler place. This is known as the heat output. We can figure out the efficiency (how well the engine works) of a heat engine with this formula:

   • Efficiency = Work out / Heat in = 1 - (Heat out / Heat in)

4. Best Possible Efficiency: The best efficiency that any heat engine can reach is called the Carnot efficiency. It can be calculated like this:

   • Carnot efficiency = 1 - (Temperature low / Temperature high)
   • Here, temperature high is from the hot source, and temperature low is from the cool place.

By understanding these steps, we can see how well different heat engines work. This helps improve the way we use energy.