Thermodynamics filled in class notes_Part_27

# Thermodynamics filled in class notes_Part_27 - 2.8. DIESEL...

This preview shows pages 1–2. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 2.8. DIESEL 61 P v T s 1 2 3 4 isobar isochore 1 2 3 4 isentrope isentrope Figure 2.17: P − v and T − s diagrams for the Diesel cycle. The thermal efficiency is found as follows: η = w net q H , (2.400) = q H − q L q H , (2.401) = 1 − q L q H , (2.402) = 1 − u 4 − u 1 h 3 − h 2 , (2.403) = 1 − c v ( T 4 − T 1 ) c P ( T 3 − T 2 ) , (2.404) = 1 − 1 k T 1 T 2 T 4 T 1 − 1 T 3 T 2 − 1 . (2.405) All else being equal, the Otto cycle will have higher efficiency than the Diesel cycle. However, the Diesel can operate at higher compression ratios because detonation is not as serious a problem in the compression ignition engine as it is in the spark ignition. Example 2.10 (adopted from BS, Ex. 12.8 pp. 501-502). An air standard Diesel cycle has a compression ratio of 20, and the heat transferred to the working fluid has 1800 kJ/kg . Take air to be an ideal gas with variable specific heat. At the beginning of the compression process, P 1 = 0 . 1 MPa , and T 1 = 15 ◦ C .....
View Full Document

## This note was uploaded on 11/26/2011 for the course EGN 3381 taught by Professor Park-sou during the Fall '11 term at FSU.

### Page1 / 2

Thermodynamics filled in class notes_Part_27 - 2.8. DIESEL...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online