Undergrad Lost Energy from a Reciprocating Piston

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The discussion centers on energy loss in reciprocating pistons within internal combustion engines, particularly during the deceleration of pistons at bottom dead center (BDC) and top dead center (TDC). While an engineering professor asserts that the flywheel absorbs and recovers energy during low-speed operation, participants argue that significant energy loss occurs at higher speeds, primarily as heat. The conversation highlights the balance of forces in multicylinder engines, where energy is shared among pistons, and counters the idea that rotary engines should be more efficient if substantial energy loss existed in reciprocating engines. Participants emphasize that energy loss is not as "tremendous" as suggested, as rotary engines like the Wankel do not demonstrate corresponding efficiency advantages. The thread seeks a conclusive understanding of energy dynamics in these systems, ideally supported by calculations.
  • #31
Consider a 4 stroke engine, with the piston at TDC on the intake stroke. The piston speed starts at zero and accelerates to its maximum speed. How do you think that happens?
 
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  • #32
JAlda333 said:
I posted the topic for discussion. My goal is not to prove anyone wrong but to exchange ideas/views. If we do not openly share our thoughts, then there will be no discussion. Hopefully, we can all arrive on one conclusion. And if we still cannot agree, I will definitely not be the judge... but perhaps the readers may be able to. Thanks again.
The issue here is that reciprocating internal combustion engine technology is extremely mature, having well over a century of technological progress and billions of production examples. This area is very well understood and there is an objectively right or wrong answer here. It's not up for a debate or an 'exchange of ideas' in the sense that you can just claim something and have an inherent right to have people seriously consider your idea. If you're going to propose something and then disagree when people correct you, please have a valid reference supporting you.

If you can find a reference supporting your claim that there is significant energy loss due to acceleration/deceleration of the pistons, feel free to contact myself or another mentor and we can discuss reopening the thread. Until then, thread locked.
 
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