Context

Introduction

Heat engines play a central role in our modern society. They are devices that convert heat, or thermal energy, into mechanical work. In this project, we will learn about the principles underlying the operation of these machines and the thermodynamic cycles that they go through in order to perform this conversion.

The three key theoretical concepts for understanding heat engines are the first law of thermodynamics, which deals with the conservation of energy and states that energy cannot be created or destroyed, only transferred or transformed; the second law of thermodynamics, which establishes that heat will always flow spontaneously from higher temperature bodies to lower temperature bodies and never the other way around, and finally, the concept of the efficiency of a heat engine, which is the ratio of the useful energy output to the energy supplied to the engine.

Regarding the thermodynamic cycles, there are three major cycles that are essential to the operation of heat engines: the Carnot cycle, the Otto cycle, and the Diesel cycle. The Carnot cycle, in particular, is important because it describes the operation of the “perfect heat engine”, the one that would have the highest possible theoretical efficiency.

Real-World Context

Heat engines are everywhere in our daily lives. They are in the internal combustion engine of our cars, the air conditioning system that keeps us comfortable during the summer months, the power plants that provide electricity to our homes and offices, and even the refrigerator that keeps our food fresh.

Therefore, understanding how heat engines work and the thermodynamic concepts behind them is fundamental for anyone who wants to have a deep understanding of how our modern society functions. Moreover, with the issues of sustainability and energy efficiency becoming increasingly important, having a solid knowledge of heat engines can open many doors to careers in engineering, physics, chemistry, and other fields.

Hands-On Activity: “A Deep Dive into Heat Engines”

Activity Title: Building a Homemade Heat Engine

Project Goal

The goal of this project is to solidify and apply the knowledge acquired on heat engines, thermodynamic cycles, and the laws of thermodynamics by building a simplified prototype of a homemade heat engine.

Detailed Project Description

Teams will build a prototype of a homemade heat engine. The prototype must demonstrate at least one thermodynamic cycle and teams must be able to explain how the laws of thermodynamics apply to the operation of their prototype.

Each team will then conduct experiments on their engine, varying one or more parameters and observing how this affects the efficiency of the engine. These experiments must be documented and discussed in the final report.

Each team must research and select an example of a real-world heat engine that relates in some way to their prototype and discuss how the principles demonstrated in their prototype apply to this real-world engine.

The project should be done in teams of 3-5 students and each student should invest 5-10 hours. The final deliverable is due in one month.

Materials List

• Glass flask
• Plastic or paper straws
• Tape
• Water
• Stove or heat source
• Thermometer
• Any other tools and materials deemed necessary for building the prototype

Step-by-Step Guide to the Activity

1. Theoretical study: Before beginning construction, teams should study the laws of thermodynamics, thermodynamic cycles, and the concept of heat engine efficiency. This knowledge will be essential to understanding the operation of the heat engines that they will build.

2. Heat engine design: Teams should then design their heat engine. The design should be documented, including schematics and explanations of how they expect the engine to work.

3. Heat engine construction: Teams should build the heat engine according to the design they have developed.

4. Experimentation: Once built, teams should conduct experiments on their engine. They should vary one or more parameters (such as the starting temperature of the water, for example) and observe how this affects the efficiency of the engine.

5. Final report: Based on the experiments conducted, teams should write a final report explaining how their engine works, the experiments they conducted and their results, and how the principles studied apply to their engine and to a real-world heat engine.

Project Deliverables

The final deliverable for this project will be the constructed heat engine and a report containing the following sections:

1. Introduction: A detailed explanation of what heat engines are, the importance of studying them, and the goals of this project.

2. Development: A detailed description of the construction of the engine, the experiments conducted, and the results obtained. It should be clearly explained how the concepts studied apply to the engine built. There should also be a discussion of how the principles demonstrated in the engine apply to a real-world heat engine.

3. Conclusions: Reflections on the learning obtained from building the engine. What worked? What didn't work? What would you do differently if you were to do it again? How did this experience contribute to your understanding of heat engines?

4. Bibliography: Citations for the sources that were consulted during the project. If online documents were consulted, the link to the document should be provided.

Upon completion of the project, in addition to acquiring technical knowledge about heat engines, students will also have developed important socio-emotional skills such as time management, teamwork, communication, and others.