Otto Cycle Engine - Key Concepts and Historical Development

Introduction

• The Otto Cycle engine is a fundamental model for internal combustion engines, developed by Nikolaus August Otto in 1876.
• Incorporates the basic processes: intake, compression, combustion, expansion (power), and exhaust in a single piston-cylinder apparatus.

Historical Context

• Stirling and Ericsson cycles were developed to address high-pressure boiler dangers of early steam engines.
• Lenoir's internal combustion engine was simpler but less efficient.
• Brayton improved efficiency by introducing a compression process before combustion.

Otto Cycle Mechanics

• Comprises two isochoric (constant volume) and two isentropic (constant entropy) processes.
• Requires four piston strokes and two crankshaft revolutions to complete a cycle.

Transition to Liquid Fuels

• Originally used illuminating gas (methane).
• Transition to liquid hydrocarbons (gasoline) began in 1885.

Technological Advancements

• Development of the float-feed carburetor by Wilhelm Maybach in 1892, pivotal for the automobile era.
• Karl Benz built the first practical automobile using Otto cycle engine.

Patent and Development Timeline

• Alphonse Eugene Beau de Rochas patented the four-stroke cycle IC engine in the 1860s.
• Otto was the first to build and operate a successful engine.
• Dugald Clerk developed a two-stroke version in 1878, introducing the concept of supercharging.

Efficiency and Calculations

• Thermal efficiency measured by specific internal energies and compression ratios.
• Example problems illustrate thermal efficiency calculations for Otto cycle engines.

Practical Applications

• Otto cycle engines became competitors to steam engines in small- and medium-sized markets.
• Used in various applications: boats, lawn mowers, saws, etc.

Alternate Cycles

Six-Stroke Engines

• Aim to increase efficiency by adding two additional strokes using steam or water.
• Variants include pair of cylinders sharing an extra cylinder.

Atkinson Cycle

• Allows higher expansion ratio than compression ratio for higher efficiency.
• Modern Atkinson cycle uses variable valve timing (VVT) technologies for efficiency.
• Widely used in hybrid electric vehicles (HEVs).

Dual-Combustion Cycle

• Combines constant volume and constant pressure combustion.
• More representative of real engine cycles.

Modern Applications and Innovations

• Atkinson engines used in HEVs for better fuel economy and emission reduction.
• Cox Tee Dee .010 model recognized as the smallest internal combustion engine.

Conclusion

• Otto cycle engines laid the foundation for modern internal combustion engines.
• Ongoing developments explore efficiency improvements and alternative cycles for various applications.