Seventh Day

Spring 2015
17th of March's Class

At the beginning of the class, we were introduced to a different type of engine from the one that we have always worked on. It is the diesel engine. It has a higher efficiency, and a different way of combusting the gas inside its cylinder; by massive pressure.

However due to its lower maximum power, which is inhibited by various factors, like the strength of the materials required to withstand the intense pressure, it is less popular than the Otto Engine.

We were also introduced to the concept of Entropy.

This red coloured mechanism is a model of Stirling Engine. It's main trait is its use of differential temperature as its source of power. The alternating temperature of the gas in contact with the metal plate is what drives the motion in this engine.

In the case above, we heated up the gas with hot water from the bottom.

Below is a short video of a Stirling Engine in action.

This website has a simple model for how the engine works: Stirling Engine

Another engine that was introduced is the Wankel Engine, which is commonly known as Rotary Engine. It uses the same 4 step cycle as Piston Engine, however it boasts a higher horsepower per gallon of fuel than the Piston Engine.

This website has a simple model for how the engine works: Wankel Engine

We were taught about COP, the Coefficient Of Performance for an engine. Then Professor Mason gave us an example about using Electric Heater and Heater Pump, and made us compare their results. The Electric Heater is much more efficient, however the Heat Pump is still more favoured as the price of gas is much cheaper than electricity.

Then we were given a question about a freezer.

The image below is how we attempt to answer the questions.