Contextualization

Hello, future physical engineers! In this incredible journey through the world of physics, we will delve into the topic of 'Thermal Machines'. Thermal machines are devices that can convert thermal energy (or heat) into mechanical work. These devices are fundamental in moving the current world. Whether it's a classic steam locomotive or the latest car engine, many of the devices we use in everyday life are based on thermal machines.

Thermodynamics is the branch of physics that studies thermal machines. It deals with the fundamental principles that govern the way energy is converted between different forms, including heat and work. Thermodynamics gives us a way to calculate the efficiency of a thermal machine and helps us understand why some machines are more efficient than others.

Understanding how thermal machines work and how they are used is not only fascinating but also extremely relevant in today's world. Many of the most pressing issues we face - such as climate change, energy efficiency, and sustainability - are directly related to the use of thermal machines. For example, power plants use thermal machines to convert fossil fuels or nuclear energy into electricity.

It is also important to note that thermodynamics and thermal machines are not isolated in the domain of Physics. They have connections with chemistry, engineering, mathematics, and even with biology and economics. Therefore, this project will be a wonderful way to see how physics is interconnected with other disciplines and has practical applications in the real world.

Here are some resources you can explore to start understanding the world of thermal machines and thermodynamics:

1. "Thermal Machines and Refrigeration" - Brasil Escola
2. "Understand what a thermal machine is" - Mundo Educação
3. "Thermal Machines" - Só Física
4. "Thermodynamics" - Khan Academy

Practical Activity

Activity Title: "Designing and Building a Thermal Machine: The Stirling Engine"

Project Objective:

This project aims to allow students to explore the concept of thermal machines by building a Stirling engine. This is an external combustion engine that operates based on the expansion and contraction of air or another gas. The challenge is to build a functional model of the Stirling engine using recyclable and easily accessible materials.

The project should be carried out by groups of 3 to 5 students, with a total estimated duration of 18 hours, considering the study of the theory, project development, engine construction, testing, and the creation of the final report.

Detailed Project Description:

The project will be divided into four main stages:

1. Theoretical Study - Students must first study in detail the topics:

   • Fundamentals of Thermodynamics
   • Carnot Cycle and thermodynamic efficiency
   • Thermal and refrigeration machines
   • The Stirling engine: Principles and Operation

2. Designing the Engine - Students must develop a detailed project of the Stirling engine, drawing the scheme, listing the necessary materials, and planning the construction and tests. At this point, it is crucial to perform calculations and estimates regarding the volume of the cylinders, piston displacement, engine dimensions, heat source, among others.

3. Construction and Testing - Students must build the Stirling engine following the developed project and test its operation. The engine must be able to move from a heat source. Students must carefully record their observations and measurements during the tests, such as the temperature of the heat source, engine speed, efficiency, and any problems encountered.

4. Final Report - Students must prepare a detailed report, explaining the entire process, from the theoretical study phase, through the engine design and construction, to the tests carried out.

Required Materials:

• Soda cans
• Shafts and wheels (can be from old toys)
• Balloons
• Wire
• Adhesive tape
• Candle and lighter
• Thermal insulating spray paint
• Infrared thermometer
• Basic tools such as pliers, scissors, hole punch, etc.

Detailed Step-by-Step for Activity Execution:

1. Theoretical Study: Research and study the topics listed above, using reliable sources such as physics textbooks and reputable educational websites.
2. Designing the Engine: Develop a detailed scheme of the Stirling engine, indicating all parts and their correct dimensions. Perform the necessary calculations to properly size the engine.
3. Construction: Follow the project to build the Stirling engine. Use the soda can to create the cylinders and the balloon for the piston. The candle will serve as the heat source.
4. Testing: Light the candle and observe the engine's movement. Use the infrared thermometer to measure the temperature of the heat source. Perform several tests to obtain consistent data.
5. Report: Document the entire process of building the engine, including the theoretical study, project development, construction, and tests. Analyze and discuss the results obtained.

Project Deliverables:

Teams must deliver:

1. The Stirling Engine Project: It must contain a detailed scheme of the engine, with all parts and their correct dimensions properly indicated. It must also include all calculations performed for engine sizing.
2. The Built Stirling Engine: The engine must be delivered along with the project. It must be functional, powered from a heat source.
3. The Final Report: It must be a written document that explains the entire process of the project. Follow the structure indicated in the preliminary part of this guide: introduction, development, conclusions, and bibliography. The theoretical study, engine design and construction, tests performed, results obtained, and conclusions derived must be documented.

Remember, the project is not just about building a functional engine, but about understanding the concepts and fundamentals that allow it to work. Use this project as an opportunity to demonstrate your understanding of thermodynamics and thermal machines.