{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Notes%2011.24.10

# Notes%2011.24.10 - Happy Thanksgiving Please note you are...

This preview shows pages 1–19. Sign up to view the full content.

1 Happy Thanksgiving!! Please note you are responsible for this material. Work any examples noted Have a safe holiday! See you all on Monday.

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

View Full Document
2 Brayton Cycle Proposed by George Brayton in 1870!
3 Other applications of Brayton cycle Power generation - use gas turbines to generate electricity…very efficient Marine applications in large ships Automobile racing - late 1960s Indy 500 STP sponsored cars

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

View Full Document
4 Schematic of simple cycle
5 TEAMPLAY What expression of the first law applies? ∆ ∆ u or h? Why?

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

View Full Document
6 Idealized Brayton Cycle
7 Brayton Cycle

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

View Full Document
8 Brayton Cycle 1 to 2--isentropic compression 2 to 3--constant pressure heat addition (replaces combustion process) 3 to 4--isentropic expansion in the turbine 4 to 1--constant pressure heat rejection to return air to original state
9 Brayton Cycle Because the Brayton cycle operates between two constant pressure lines, or isobars, the pressure ratio is important. The pressure ratio is not a compression ratio.

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

View Full Document
10 Brayton cycle analysis in net q w = η As with any cycle, we’re going to concern ourselves with the efficiency and net work output: comp turb net w w w - = Efficiency: Net work:
11 1 2 comp h h w - = - w h h comp = - 2 1 1 to 2 (isentropic compression in compressor), apply first law: When analyzing the cycle, we know that the compressor work is in (negative). It is standard convention to just drop the negative sign and deal with it later: Brayton cycle analysis

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

View Full Document
12 2 3 23 in h h q q - = = 2 to 3 (constant pressure heat addition - treated as a heat exchanger) Brayton cycle analysis
13 or , h h w 3 4 turb - = - 4 3 turb h h w - = 3 to 4 (isentropic expansion in turbine) Brayton cycle analysis

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

View Full Document
14 , h h q 4 1 out - = 1 4 out h h q - = 4 to 1 (constant pressure heat rejection) We know this is heat transfer out of the system and therefore negative. In book, they’ll give it a positive sign and then subtract it when necessary. Brayton cycle analysis
15 Brayton cycle analysis Or, substituting: comp turb net w w w - = The net work is: ) h (h ) h (h w 1 2 4 3 net - - - =

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

View Full Document
16 Let’s get the efficiency: Brayton cycle analysis in net q w = η ) h (h ) h (h ) h (h 2 3 1 2 4 3 - - - - = ) h (h ) h (h 1 2 3 1 4 - - - = η
17 Brayton cycle analysis Let’s assume cold air conditions and manipulate the efficiency expression: ) T (T c ) T (T c 1 2 3 p 1 4 p - - - = η ( 29 ( 29 1 T T 1 T T T T 1 2 3 1 4 2 1 - - - = η

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

View Full Document
T T p p k k 2 1 2 1 1 = - ; T T p p p p k k k k 4 3 4 3 1 1 2 1 = = -
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 66

Notes%2011.24.10 - Happy Thanksgiving Please note you are...

This preview shows document pages 1 - 19. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online