IC Engines Air-Standard Otto, Diesel and Dual Cycles

The Diesel cycle is a reciprocating internal combustion engine’s combustion process. The heat generated by the compression of air in the combustion chamber ignites the fuel, which is subsequently injected into the combustion chamber. This is in contrast to the Otto cycle (four-stroke/petrol) engine, which uses a spark plug to ignite the fuel-air mixture. Aircraft, vehicles, power generation, diesel-electric locomotives, and both surface and submarine ships employ diesel engines.

Many model aeroplanes have “glow” and “diesel” engines that are relatively basic. Glow plugs are used in glow engines. Variable compression ratios are found in “Diesel” model aeroplane engines. Both types rely on unique fuels.

External flames, exposed through valves, were utilised for ignition in several 19th-century or earlier experimental engines, although this becomes less appealing as compression increases. (The thermodynamic value of compression was discovered thanks to Nicolas Léonard Sadi Carnot’s research.) This implies that the diesel engine may have been invented without the use of electricity in the past.

Dual cycle :

The dual combustion cycle (also called the mixed cycle, Trinkler cycle, Seiliger cycle, or Sabathe cycle) is a thermal cycle that combines the Otto and Diesel cycles. It was first introduced by Russian-German engineer Gustav Trinkler, who never claimed to have invented it.The dual cycle, also known as the limited pressure cycle, is a thermodynamic cycle that combines the Otto and Diesel cycles into one. In the dual cycle, combustion takes place in two stages: constant volume and constant pressure. It’s a term that can be applied to internal combustion engines. Heat is provided in two ways: at constant volume (isochoric) and at constant pressure (isobaric), with the latter providing more time for the fuel to totally combust. This cycle is generally utilized for Diesel and hot spot ignition engines due to the lagging characteristics of fuel. It is made up of two adiabatic processes, two constant volume processes, and one constant pressure process.

In a diesel engine, the dual combustion cycle is used. The dual combustion cycle is an ideal air standard closed cycle with five operations, the first of which is heat addition at constant volume, followed by heat addition at constant pressure, and finally rejection at constant volume. This is something that can be used in diesel engines.

Otto cycle and diesel cycle :

A typical spark ignition piston engine is described by an Otto cycle, which is an idealised thermodynamic cycle. It is the most frequent thermodynamic cycle seen in car engines. 

The Otto cycle is a description of what occurs to a mass of gas as pressure, temperature, volume, heat addition, and heat removal are changed. The system refers to the mass of gas that is subjected to those changes. The fluid (gas) within the cylinder is defined as the system in this situation. It will also describe the system’s effect on the environment by detailing the changes that occur inside the system.

The Otto cycle is a thermodynamic cycle that converts chemical energy into heat energy and then heat energy  into mechanical energy.

Constant volume cycle is another name for the Otto cycle. The constant pressure cycle is the name given to the diesel cycle.

The explosion process is carried out at a steady volume rate. The explosion process in a diesel engine takes place at a steady pressure.

In the Otto cycle, both intake and exhaust valves move up and down, while in the Diesel cycle, only one valve moves up and one moves down.

The Otto cycle and diesel cycle are two main types of the cycle used for engines.

It consists of four stages: 

• Suction
• Compression
• Expansion
• Exhaust

The term “cycle” refers to the notion that an engine undergoes as it performs work on its environment (in this case, turning a shaft). It’s also used in physics and chemistry when referring to chemical reactions or physical processes that repeatedly occur in cycles or “steps.”

Diesel and dual cycle :

The dual cycle engine is a new technology that has been developed to help reduce these harmful effects on air quality. It reduces fuel consumption by up to 40% while providing more power than an equivalent diesel engine.

The diesel cycle is the most common type of two-cycle engine. It uses a compression ignition system with an air intake and exhaust valve at each end of the cylinder. The power stroke powers the piston back down to repeat the process. This process repeats until all of the fuel is gone from one cylinder, which then starts on another one.

The diesel cycle is the most popular and widely used power source for vehicles on the road. The fundamental distinction between otto, diesel, and dual cycle is how heat is added to the thermodynamic process. Heat is added to the engine in the Otto cycle in an isochoric manner, that is, when the piston is at top dead centre. It is a heat addition cycle with a constant volume.

Diesel engines have been in use for more than a century. They are the most popular and widely used power sources for vehicles on the road. The dual cycle is one of the ways to improve diesel engine performance, which aims to reduce fuel consumption while improving emissions.

Conclusion:

The diesel cycle is a four-stroke engine cycle that converts heat energy from burning fuel into mechanical energy by expanding the heated gases. The diesel cycle consists of four phases: intake, compression, combustion, and exhaust. The intake phase starts with the piston moving downward in the cylinder to suck in air . The compression phase then occurs where the piston compresses the air  by squeezing them together before combustion occurs.