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**Unformatted text preview: **EML 3100 — Exam 3 — Fall 2012 Friday: November 30 Problem 1 120 points): Consider the ideal, steady-state gas-reﬁ'igeration cycle shown in the schematic below.
The working ﬂuid is helium and the following operating conditions are known; Use properties for helium at
STP and assume that the speciﬁc heats are constants.
T] = -125 °C, T2 = 275 °C, 7‘; = 50 °C, T4 = —185 °C, PQ/P] = 26,
TL: 175 K, TH: 300K “hi 7LT “M 2 (A) Complete the vertical axis of the phase diagram provided by labeling the mean effective temperatures, T;
and T13, the min. and max. process temperatures, TL and TH, and the reservoir temperatures, TL and TH.
(B) Calculate the mean effective process temperature, TL" . ‘ II l 1 LCD M~las+a7say a {33—} 37345 Problem 2 (20 gointsz: An ideal turbojet engine With an afterburner is shown in the schematic below. Assume
the air-standard model holds and the engine operates in steady-state with the following conditions. T2=605K, T3=1200K, T4l,.=896K, T4b=1600 K, ]}=1367K, k = 9/7, FHV= 43,000 kJ/kg-ﬁiel QHI OH = 0H1 + 0H2 = nix-FHV (A) Calculate the effective average specific heat, cp,
for the air in the engine. (B) Calculate the air-to—ﬁlel ratio, AF. (C) Calculate the jet velocity V}. 6)
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5 Problem 3 [20 points): A fossil-fueled steam power plant operates on the basic Rankine cycle shown in the
schematic. The following operating conditions are known. P] =10 kPa, v] = 0.001010 m3/kg, P2 = 15000 kPa, h; = 3308.5 kJ/kg, _ Izp=75 %, m=85 %
GD 63) (:9 0” Determine P4, 343, and the net work produced per unit mass of steam Wm. @ \Vms ’W 5% ~ 5% M3,)ollgl CD 63‘“; \(tha
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@ Problem 4 120 points): Consider the ideal, steady—state Brayton cycle with reheat shown in the schematic
below. The air—standard model holds and the following operating conditions are known. P1=100kPa, T1=3OOK,P2=900kPa, T3=1100K, T4=750K, T6=1100K,
k=4/3 Determine T2 and Ta _C7g I:
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T: 5mg keg Problem 5 (20 points): For each of the systems below (1) identify the base cycle from the given list, (2)
identify any relevant cycle modiﬁers (choose all that apply), and (3) identify the labeled devices from the given list. _
DeVIces: Burner
Compressor
Condenser
Evaporator
lntercooler
Turbine Pump
Regenerator
Steam Generator
Valve Base Cycles: Brayton Cycle
Diesel Cycle
Gas Refrigeration Cycl- (1) Base Cycle: Vgﬁ- 4' ‘ all that apply: Otto Cycle
Rankine Cycle
Vapor Compression Cycle (1) Base Cycle: Rgﬂkwe
(2) Circle all that apl : we; A. HDEM § B. EVAPOﬁA/TD K
C- M D. [Put/VIP E. COMDWSEK F. NTERCOGLER ‘G. TuﬂEnME (1) Base Cycle: Gns Qseeigggtw
(2) Circle all that apply: 7 Intercooling Reheat H. KEEN: ng (1) Base Cycle: BmYWN’ V
(2) Circle all that apply: Intercooling‘ Reheat ' ...

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- Spring '08
- Chung
- Combined cycle, Thermodynamic cycles, Brayton cycle, Afterburner, base cycle