Pressure coefficient of a diesel engine

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Discussion Overview

The discussion revolves around the concept of the pressure coefficient in the context of diesel engines, specifically exploring whether it can be calculated using heat exchanger and exhaust calorimeter data, alongside dynometer readings. The conversation touches on definitions and implications of the pressure coefficient.

Discussion Character

  • Debate/contested, Conceptual clarification

Main Points Raised

  • One participant inquires about the possibility of calculating the pressure coefficient of a diesel engine using specific temperature readings and asks for the required formula.
  • Another participant expresses confusion about the term "pressure coefficient," noting their familiarity with pressure ratios in diesel engines but not with this specific term.
  • A participant asserts that a pressure coefficient cannot be defined for an entire engine, suggesting it may only apply to specific points of fluid flow within the engine.
  • There is a clarification regarding the abbreviation "Cp," with one participant initially confusing it with specific heat at constant pressure, acknowledging the change in pressure during the combustion cycle.
  • Subsequent posts reflect a light-hearted acknowledgment of the abbreviation confusion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the definition or applicability of the pressure coefficient in the context of diesel engines, with some expressing skepticism about its relevance to the engine as a whole.

Contextual Notes

There is ambiguity regarding the definition of "pressure coefficient" and its applicability to the engine versus specific flow points. The discussion also highlights the potential confusion arising from the abbreviation "Cp," which can refer to both pressure coefficient and specific heat at constant pressure.

Who May Find This Useful

This discussion may be of interest to those studying thermodynamics in engines, particularly in relation to pressure measurements and their implications in engine performance analysis.

Ry122
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With Heat exchanger, Exhaust Calorimeter (water and gas) temperatures along with dynometer readings for each temperature reading, is it possible to calculate the pressure coefficient of the engine?
If so, what formula would be required?
 
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I have calculated pressure ratio's in diesel engines before but I have never heard of a pressure coefficient. What is that? By knowing that value what can one learn from it?

Thanks
Matt
 
You can't have a Cp for an engine, as Cp conerns the relative pressures in flow of fluids.

So you could have Cp for points of flow in the engine. But not the engine itsself.
 
Ohh, you mean the specific heat of costant pressure? Yes, you cannot have this since as the combustion cycle, cycles, the pressure is changing.

Thanks
Matt
 
CFDFEAGURU said:
Ohh, you mean the specific heat of costant pressure? Yes, you cannot have this since as the combustion cycle, cycles, the pressure is changing.

Thanks
Matt

Nah I was just using Cp for pressure coefficient. I forgot that specific heat has the same abbreviation/symbol.
 
LOL, okay.

Thanks
Matt
 

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