Understanding Specific Power in Engines — Lesson 2

This lesson covers the specific power of the spark ignition in internal combustion engines. It explains the concept of specific power, its calculation, and its significance in the functioning of an engine. The lesson also discusses the compression ignition diesel engine, its advantages, and its disadvantages. It further elaborates on the concept of compression ratios and their impact on the engine's performance. The lesson also touches upon the strategies to increase specific power, such as adding more cylinders, and the limitations of these strategies. The lesson concludes with a detailed explanation of the air standard diesel cycle and its efficiency.

Video Highlights

00:20 - Specific power and its representation on a diagram
05:13 - Working of compression ignition engine
16:57 - Comparison of the specific power output of the air standard diesel cycle with the Otto cycle
18:55 - Thermal efficiency of the air standard diesel cycle
25:45 - Comparison of the second law efficiency of the air standard diesel cycle with the Otto cycle

Key Takeaways

- The specific power of a spark ignition engine is not very high and can be increased by adding more cylinders. However, this strategy deteriorates the power-to-weight ratio of the engine.
- Compression ignition diesel engines offer higher specific power and thermal efficiency but emit more pollutants.
- The performance of these engines is controlled by certain parameters, and understanding these can help in designing more efficient engines.
- Despite being an ideal analysis, the variations and insights from the cold air standard analysis can be applied to real engine design.