APPLIED THERMODYNAMICS (SKMM 2423)

TEST 1 (Sem 1 2016/2017)

15/10/2016

(2:00 pm – 3:30 pm)

ANSWER ALL QUESTIONS

Question 1 (10 marks)

Steam is supplied to a two-stage turbine at 40 bar and 350° C. It expands in the first turbine until it is just dry

saturated, then it is re-heated to 350° C and expanded through the second-stage turbine. The condenser pressure

is 0.030 bar. Assume ideal processes and neglecting the feed-pump term (refer to Table 1: Property Table for

water).

a) Sketch and label the schematic diagram of the steam plant.

b) Sketch and label the cycle on a temperature-entropy (T-s) diagram.

c) Calculate the work output per kilogram of steam for the plant, [kJ/kg].

d) Calculate the heat supplied per kilogram of steam for the plant, [kJ/kg].

e) Determine the specific steam consumption, [kg/kWh].

f) Calculate the cycle efficiency, [%].

Question 2 (10 marks)

In a marine gas turbine unit a high pressure (HP) stage turbine drives the compressor, and a low pressure (LP)

stage turbine drives the propeller through suitable gearing. The overall pressure ratio is 4/1, the mass flow rate is

60 kg/s, the maximum temperature is 650° C, and the air intake conditions are 1.01 bar and 25° C. The

isentropic efficiencies of the compressor, HP turbine, and LP turbine, are 0.8, 0.83, and 0.85 respectively. The

mechanical efficiency of both shafts is 98%. Neglect kinetic energy changes, and the pressure loss in

combustion. (For air: take cp = 1.005 kJ/kgK and γ = 1.4. For combustion and expansion process: cp = 1.15

kJ/kgK and γ = 1.333).

a) Sketch and label the schematic diagram of the plant.

b) Sketch and label the process on a temperature-entropy (T-s) diagram.

c) Calculate the pressure between turbine stages, [bar].

d) Determine the cycle efficiency, [%].

e) Calculate the shaft power, [kW].

Table 1: Property Table for water (for Question 1 only)

Q*,ay.{.s- I

\A) o,4

$".*- 1olrr,,j

h,,5r= 9? --

f,-r",- 1.|rccD "4

(\<.".",..r ), \ Ul

adt 1

:t:t vV,)lru c

$o 9., h J5o'c )

h,-. lulr.t y5, , r.r8Y #

Lr

{.-.- 7 r*- t

?r- --

hr=

q* 5.--. (.fry Wh1r

o

.-[J i

I

\

S,,

.{'^ 1qv ,

lo l"-tht, >Ytr?.t ,rr\

".,t_ O.of !-y4 to lor I I fi,'c

ltrr.r- w\,

}'tot o\*

5l= n.)fVl 6Mf\, t'ar2

%;.hr' L[o.1.tr Vt\htr, >yrg uh.

O'Ol Lcl

5*" Sr, 91 ) ot.9 Iq.

}'tor .. o'1 rY1 'r 4v Q'*-)tp o' 9*ef

''i No* ' (\.. - \, * (h, - h')

h*=h++otfOl .,2 100'1t r(o.rvf)(uYw)-. Ll (e *rV

hu.Lr;\+go."?!.2.

: too.{g V\.

4

@

)

CD

@ S.t.c ? SGoo ? )6oo -t L'x V'rdo* t')of 'Y

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? \Jo8.9 r,fl, K

,]-

q^ 't Qu, + Qq

, Qo',r.)- r.sp-1 )+Q,ft', - vt?1' t)

C,

lvs

16

9\*. Ir?*Y"i > 6o Alt'[, , b.fu'C- 1>l r

P, : l'Otl-',1t , 'v{ct 4tk-

Lit," , o'd

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1

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1

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'(, ' 'i,o'tr> V\>-s->1f

tT, ' 'l'1tr

7v: ttq K --F O

t.rrrf (vat ->f t)

l8t.r' uflr:; --_ c)

w*r,o = L?,. la/c i,,o'1s

lr t'l t

o -1r1t-1y

"t1 :'[\ )

= tbt.V tc_ rr t.Y + ti-l16t-u rc

cf," ( .-1) (?r-tt).

r.rr[1r- rJ :

tir,* = 1t'1'r -

t'' 17s

o'81 ? 1r,1 Ttvu

'll,,t ' 1 "'1.t , Tv?f L

G?-?,

)

?t

t.l

il*: r.f Gr *X {)

iw*tr1"t-'[tl4tv

'[ tr"-?6t"b

1rs

T*tr )

/ ?r\-7'\r"1

,.?r/vt)

"t,-**) t

: ((z.t K

I ^.f/n

\^),^4{-

= L?,tG- zr)

r.rf (?br,6 - b"rv."r.)o,

, "7,

rL= I7q*.

.tt k, - i)t-t(trr-y7,)J-lo.o *lV. _

1r

o

Ut*.+ + ;

76 LbottS 6o L f

--o

y6--'-'fto. 6

bi(1

Tu.r7w1

?*

Q,* -.

'l ,- . ^- = -i*-'[,

1* -1no-ff -- ?6t'U-'l:'

Yol'b t' t >'f

1r = 6rry.r- f_.

ty_1,1,* _

f\+ fvtr =