Chapters 1.2, 1.3

These initial sections give a brief overview of what Stirling Engines are capable of, what they are and how they work. The brief nature of these initial chapters is highlighted in chapter 1.2, which is simply a list of principles and characteristics of the engine, combined with where to get more information for each principle.  These facts lead into chapter 1.3 – What is a Stirling Engine? This chapter explains that the Stirling Engine “is a closed regenerative cycle heat engine which operates at high mean gas pressures, in an oil-free environment, with no valve gear, with energy transfers through the cylinder walls” (Reader, 4). The chapter continues to show a schematic diagram (to the right) comparing the differences between the Stirling and Internal Combustion (IC) Engines. From this diagram I got the impression that the Stirling Engine is a more sophisticated machine in terms of efficiency and having the ability to utilize multiple energy sources (off the top of my head an engine that uses the temperature of water in lakes to power boats or a very sensitive engine that generates power from the heat of your hand). Furthermore, it appeared that the IC Engine is straightforward and as a result loses efficiency
and some sophistication.  The chapter concludes by introducing the regenerator showing how it improves efficiency.

Essentially, these chapters showed that at the Stirling Engine despite being a very complex machine can be explained using everyday observations, but full understanding of the Engine requires more knowledge. At its very basics the Stirling Engine is an air-tight box, in which a pressurized gas is heated and cooled by an external heat source which increases and decreases the pressure within the box, moving a piston up and down. Since more work has to be applied to move the piston upwards than downwards, mechanical energy can be created. Interestingly, when heat is put into a Stirling Engine mechanical energy is outputted, but if mechanical energy is put into a Stirling Engine (by rotating its flywheel) hot and cold heat is outputted (Chapter 1.2). Although I understand how the former works, this system confuses me as depending on the direction the flywheel is rotated the location of the hot and cold heat also reverses. After reading chapters 2.1 (Thermodynamics) and 2.2 (Heat Transfer) I will hopefully better understand how this works.

The chapter ends introducing the Regenerator which I found to be a neat, yet very simple idea. Basically, instead of having the heat sources cool the hot gas all the way down to a cold temperature and losing all the energy they had the gas flows through a regenerator collecting some of the heat. Without getting too complex, a regenerator is a group of stainless steel wires that the gas flows through to pre-cool or pre-heat the gas. This is because when the gas flows from hot to cold the gas is hotter than the regenerator. Therefore, the gas gives some of its heat to the regenerator, cooling the gas while heating the regenerator. When the gas returns, moving from cold to hot, the gas is colder than the regenerator and therefore is preheated returning some of the energy it lost during the previous phase. As a result the regenerator pre-heats and pre-cools the gas, using energy that would otherwise be lost which makes the engine more efficient. The other parts of the Stirling Engine are discussed in chapter 1.4, which will be posted shortly.

Talked to Mr.H

Confirmed slightly changing the plan with Mr. H today. All is good. The new plan will be reading about 16-20 pages a day to complete around 200 pages within 2 weeks. The textbook chapter lengths vary from 2 pages to over 30. As a result, some posts will cover multiple chapters while others will not.

Created Timeline

Got distracted today with other work, so didn't have time to work on the project beyond setting out a timeline to finish in 2 weeks. I've made some changes from the initial plan, so will talk to Mr.H tommorow before posting them and pushing onwards.

More reading

I'm continuing to read the textbooks I picked up at McMaster on Thursday.The more I work on this the more it appears to fit in the Advanced topic ISU category. 

More Research!

Over the past few days I've been spending about an hour each night reading my fathers physics textbooks to better understand the concepts I briefly read about online. Unfortunately the textbooks reference things I'm yet to learn, so progress has been very slow. Regardless I'll push onwards, I have a good sense of why the engines are shaped as they are and what the purpose of each part is. Soon I think I'll be able to start choosing resources and weights for different parts to attempt some calculations as to how much mechanical energy will be generated.

In hopes of speeding up progress I went to McMaster's engineering library today to find some books specifically on Sterling Engines. I ended up buying a $60 library card for the year and renting out 4 books for the next two weeks. They appear to be very promising after reading the first few pages!

Been Researching...

I've spent the last few days researching the Stirling cycle, and have made decent progress as to how the one cylinder engine runs. The engine goes through four phases as shown here and here. Over the weekend I will continue to try to get a better grasp of how the more effective alpha engine works. My engine will likely be an alpha engine, and designs should begin by early next week at the latest.

edit: Forgot to mention that I've retrieved the sterling engine kit my brother got for Christmas, which has helped tremendously in understanding the mechanics.  

It Begins!

I have chosen to do the design category for my physics ISU. Over the next few weeks I will be researching, designing and creating the layout of a Sterling Engine powered generator with the goal of outputting 5-10 volts in order to charge an smartphone and other handheld devices when a wall outlet is not readily available.