Thermodynamics filled in class notes_Part_26

Thermodynamics filled in class notes_Part_26 - 59 2.7. OTTO...

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

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 59 2.7. OTTO One uses the isentropic relations for state 4: T3 T4 V4 V3 k −1 = T4 T3 V3 V4 k −1 = = T3 V2 V1 k −1 T4 = T3 V1 V2 1−k T4 = (3600 ◦ R)(8)1−1.4 , (2.381) = ◦ (2.382) , (2.377) , (2.378) , (2.379) , (2.380) 1566.99 R. For the pressure at state 4, use the ideal gas law: P4 V4 T4 = P4 = = P3 V3 , T3 V3 T4 P3 , V4 T3 V2 T4 P3 , V1 T3 (2.383) (2.384) (2.385) = (53.3333 atm) = 1 8 2.90184 atm. 1566.99 ◦ R , 3600 ◦ R (2.386) (2.387) The thermal efficiency is η 1 , k rv −1 1 = 1 − 1.4−1 , 8 = 0.564725. = 1− (2.388) (2.389) (2.390) CC BY-NC-ND. 18 November 2011, J. M. Powers. 60 CHAPTER 2. CYCLE ANALYSIS Now get the mean effective pressure Pmef f . Wnet = Pmef f = = = = Pmef f (Vmax − Vmin ), Wnet , Vmax − Vmin m(u3 − u4 ) + m(u1 − u2 ) , V1 − V2 cv T 3 − T 4 + T 1 − T 2 m , V1 1 − V2 V1 P1 V1 cv T3 − T4 + T1 − T2 , RT1 V1 1 − V2 V (2.391) (2.392) (2.393) (2.394) (2.395) 1 = P1 cv T3 − T4 + T1 − T2 , V T1 R 1 − V2 (2.396) 1 = P1 1 T3 − T4 + T1 − T2 , V T1 k − 1 1 − V2 (2.397) 1 = (2.398) = 2.8 1 atm 1 3600 ◦ R − 1566.99 ◦ R + 540 ◦ R − 1240.59 ◦ R , ◦ R 1.4 − 1 540 1− 1 8 7.04981 atm. (2.399) Diesel The air standard Diesel cycle approximates the behavior of a Diesel engine. It is modeled as a fixed mass system. Here the compression is done before injection, so there is no danger of premature ignition due to detonation. No spark plugs are used. Diagrams for P − v and T − s for the Diesel cycle are shown in Figure 2.17. One can outline the Diesel cycle as follows: • 1 → 2: isentropic compression in the compression stroke, • 2 → 3: isobaric heating in the combustion stroke, • 3 → 4: isentropic expansion in power stroke, and • 4 → 1: isochoric rejection of heat to the surroundings. CC BY-NC-ND. 18 November 2011, J. M. Powers. ...
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_26 - 59 2.7. OTTO...

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

View Full Document Right Arrow Icon
Ask a homework question - tutors are online