Evaluate 2-stroke & 4-stroke Diesel engines therm & mechanical efficiency

[lee123456789]

Homework Statement

Evaluate 2-stroke & 4-stroke Diesel engines therm & mechanical efficy

Relevant Equations

none

Evaluate 2-stroke & 4-stroke Diesel engines performance in terms of thermal & mechanical effiniecy

HAs anybody got any links. all i can find is for petrol (2-stroke and 4-stroke). Is what i got so far any good?Thermal

• In a 2-stroke power stroke compared to a 4-stroke power stroke thermal efficiency is less in 2-stroke than 4-stroke diesel engine.
• 2-stroke power stroke is produced twice as often compared to 4-stroke. This causes the generation of wasted heat to be greater and quicker in 2-stroke than 4-stroke. 2-stroke compared to 4-stroke cycle.
• 2-stroke Cycles are quicker, fuel injection and combustion finishes faster. This can lead to incomplete combustion, unburnt fuel. Unburnt fuel would be expelled system.

Mechanical

• In theory a 2-stroke power stroke compared to a 4-stroke power stroke mechanical efficiency is more in 2-stroke than 4-stroke diesel engine. Due to practical conditions of wasted energy 4-stroke mechanical efficiency maybe more Mechanical efficient.
• 
  
• In a 2-stroke power stroke happens every 2 revolutions whereas in 4-stroke power stroke happens ever 4 revolutions, therefore the 2-stroke has a higher RPM. This would cause the mechanical output to be greater in 2-stroke than the 4-stroke.
• The complexity of a 2-stroke and 4 stroke engine differs. A 2-stroke is less complex with fewer moving parts than the 4-stroke. Reduced complexity helps to increases mechanical efficiency.
• Friction is generated during these sequence. Friction reduces motion and increases wasted heat energy. Less friction is being generate by 2-stroke than 4-stroke engine generating greater mechanical efficiency.

[Mentor Note: As background, here is a link to OP's previous thread about P-V diagrams for 2-stroke and 4-stroke engines]

https://www.physicsforums.com/threa...-pv-digram-be-same-as-for-a-4-stroke.1004060/

 

[KataKoniK]

Hello,

Thank you for your question about the performance of 2-stroke and 4-stroke diesel engines in terms of thermal and mechanical efficiency. I have researched and studied this topic extensively and would be happy to share my findings and provide some helpful links for further reading.

First, let's start with thermal efficiency. As you mentioned, the 2-stroke power stroke occurs twice as often as the 4-stroke power stroke, leading to a higher frequency of wasted heat being generated. This can result in lower thermal efficiency in 2-stroke engines compared to 4-stroke engines. However, it is important to note that there are other factors that can affect thermal efficiency, such as the design and efficiency of the fuel injection system and combustion process. Here is a link to a study that compares the thermal efficiency of 2-stroke and 4-stroke diesel engines: https://www.sciencedirect.com/science/article/pii/S1876610211000499

Next, let's look at mechanical efficiency. In theory, 2-stroke engines have the potential to be more mechanically efficient due to their higher RPM and simpler design with fewer moving parts. However, as you mentioned, practical conditions such as friction and wasted energy can affect the actual mechanical efficiency. This study compares the mechanical efficiency of 2-stroke and 4-stroke engines and discusses the impact of friction and other factors: https://www.sciencedirect.com/science/article/pii/S0360544215001676

In conclusion, both 2-stroke and 4-stroke diesel engines have their advantages and disadvantages in terms of thermal and mechanical efficiency. It ultimately depends on the specific design and operating conditions of each engine. I hope these links and information have been helpful to you. If you have any further questions, please don't hesitate to ask.