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Solutions to thermodynamic problems
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MEEN 301 Thermodynamics Name:_-f/<:"";::' ::...:oe•••••~'7/ _
Dr.Shana Spring 2013 Date: _
1. (25 points)
A Carnot engine operates between two temperature reservoirs maintained at 200°C and 20°C,
respectively. If the desired output of the engine is 15 kW. Determine the heat transfer from the
high-temperature reservoir and the heat transfer from the low-temperature reservoir.
1
2. (25 points)
After a combustion process in a cylinder, the pressure is 1200 kPa and the temperature is
350°C. The gases are expanded to 140 kPa with a reversible adiabatic process. Calculate the
work done by the gases, assuming they can be approximated by air with constant specific heats.ort -W~
T ~fA} z: """
W=W _U,_UL..-~ C~ T\ ---(J)
::::: ~\1 i o,\,) {"2....- - ,}
" " V)..\,-O/P" L~ftu- fY/J{;e4J ....i/) ue V L'
.--:--(" --- (P2..-)~ ~ (, 23 tfiJ;lf 0 )~L.- - (f - - i'Z.f51Jf,
l.(go k-
1
-,
(
.,,-- -~ -
lvA-VI
@-:::9u.J::- "L/O Lh'L3 - ?31), ..
2
3. (25 points)
A piston-cylinder device contains 0.75 kg of nitrogen gas at 140 kPa and 3rc.The gas is compressed slowly in a polytropic process during whichPV1.3= constant. The process ends when the volume is reduced by one-half.Determine the entropy change of nitrogen during this process.
M :=;: 0 "7~/4---QJ ~ I40 It:- ~CA.
I tJ1 C - 3ior-.it -z: 3'7 -V - O ..sv,2---
~ I ,'3. )k _(~)-:::_ :L -z: I, '2-51~ -\:.v--r; ~~ Tz- z: /,2-:>/1 ('TI) ;:0 3§/,bS-
52-- - 5, zz: LV L T2 -t f-.Q---, \I:L
" VI--r /v?, L/ {)C. -==7 L-." I A-V :::- ..7~II .E'--rIhl --- t:"-s JC--
~ ,'1'/v.L, U' j.. '5 II).{- ~.3/l) £v. O'~S:t-- -- 5, -- ~g'1J1
__ ~fcJ~ ~,.- \ oS' i-q
S'"L--~Sl'-- ML-S-z..-S,) -Jz: D' 75: ~)< ,~!£.: Af1 EJ
v 03i l1 J:::-3
---~-------------------------------------------
4. (25 points)
An inventor has proposed the insulated device shown which operates with H20 as the medium.
Determine T3.
"rnj= 3.03 kg/sP1=4 MPar,= 5000 C
Insulated
4