Otto and Diesel Cycle: Heat Addition & Cutoff Ratios

Click For Summary

Discussion Overview

The discussion revolves around the differences between the Otto and Diesel cycles, specifically focusing on the methods of heat addition and the concept of cutoff ratios. Participants explore the implications of constant volume versus constant pressure heat addition in these thermodynamic cycles.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that the Otto cycle involves constant volume heat addition to the air-fuel mixture, while the Diesel cycle involves heat addition at constant pressure.
  • Others mention the concept of cutoff ratios in the Diesel cycle, suggesting it is a significant aspect of its operation.
  • A participant references historical context, mentioning Rudolf Diesel's initial use of coal powder as fuel and the subsequent transition to petroleum oil, which allowed for combustion at approximately constant pressure.
  • One participant questions whether the thread is a duplicate of an existing discussion on the Diesel cycle.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the differences between the cycles, with some providing historical context while others focus on technical aspects. There is no clear consensus on the implications of these differences or the reasons behind them.

Contextual Notes

Some statements lack detailed explanations of the underlying thermodynamic principles, and there are references to external sources that may not be universally accepted or verified within the discussion.

venkata
Messages
4
Reaction score
0
In case of Otto cycle we consider that heat is immediately added to air fuel mixture(i.e constant volume heat addition) but in case of diesel cycle we consider heat addition at constant pressure and we also talk of cutoff ratios.why so??
 
Engineering news on Phys.org
venkata said:
In case of Otto cycle we consider that heat is immediately added to air fuel mixture(i.e constant volume heat addition) but in case of diesel cycle we consider heat addition at constant pressure and we also talk of cutoff ratios.why so??
There are pros and cons to each. have you done a google search for this question?
 
venkata said:
In case of Otto cycle we consider that heat is immediately added to air fuel mixture(i.e constant volume heat addition) but in case of diesel cycle we consider heat addition at constant pressure and we also talk of cutoff ratios.why so??
http://charming.awardspace.com/otto_diesel/otto_diesel.html
In this website you can find explanations about the diesel engine, how and why it was developed,etc..
I read in an article that Rudolf diesel initialy used coal powder as fuel(sprayed over hot compressed air)but the combustion increased the pressure higher than the permissible limits so that the cylinder exploded during a trial.Later petroleum oil was used and the fuel was injected at lower rates so that combustion occurs approximately at constant pressure rather than constant volume.
 

Similar threads

Otto & Diesel Cycles: Heat Addition/Rejection Processes
  • · Replies 19 ·
Replies
19
Views
5K
Expansion in non-adiabatic Otto / Diesel cycles
  • · Replies 13 ·
Replies
13
Views
2K
Increasing Diesel Engine Efficiency with Retractable Plates
  • · Replies 10 ·
Replies
10
Views
2K
Question regarding the Otto cycle
  • · Replies 2 ·
Replies
2
Views
2K
Engineering Reviewing Efficiency of Otto & Diesel Cycle Heat Engines
  • · Replies 8 ·
Replies
8
Views
4K
Automotive Air fuel ratio effects in diesel vs. petrol engines
  • · Replies 11 ·
Replies
11
Views
23K
Behavior of heat addition in a compressible flow
  • · Replies 9 ·
Replies
9
Views
4K
Otto cycle combustion heat question
  • · Replies 4 ·
Replies
4
Views
3K
Specific heat in for the Otto cycle
  • · Replies 1 ·
Replies
1
Views
2K
Why does heat addition happen at constant pressure in diesel cycle ?
  • · Replies 14 ·
Replies
14
Views
27K