This preview shows pages 1–8. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Aftercooler
Boiler
Condenser
Combustor
Compressor
Deaerator
Dehumidiﬁer
Desuperheater Diffuser
Economizer
Evaporator
Expander
Fan/blower
Feedwater heater
Flash evaporator
Heat engine Heat exchanger
Heat pump Heater
Humidiﬁer
lntercooler
Nozzle Mixing chamber
Pump Reactor
Regenerator
Steam generator
Supercharger Superheater
Turbine
Turbocharger Throttle
Valve Cool a ﬂow after a compressor Bring substance to a vapor state Take 9* out to bring substance to liquid state
Burn fuel; acts like heat transfer in Bring a substance to higher pressure
Remove gases dissolved in liquids Remove water from air Add liquid water to superheated vapor steam to
make it saturated vapor Convert KE energy to higher P LowT, low—P heat exchanger Bring a substance to vapor state Similar to a turbine, but may have a q Move a substance, typically air Heat liquid water with another ﬂow
Generate vapor by expansion (throttling) A device that converts part of heat into work
Transfer heat from one medium to another A device moving a Q from TN to Thigh, requires
a work input, refrigerator Heat a substanCe
Add water to airw—water mixture
Heat exchanger between compressor stages Create KE; P drops
Measure ﬂow rate Mix two or more ﬂows Same as compressor, but handles liquid Allow reaction between two or more substances
Usualiy a heat exchanger to recover energy Same as boiler, heat iiquid water to superheat vapor A compressor driven by engine shaft work
to drive air into an automotive engine A heat exchanger that brings T up over T3,,at
Create shaft work from high P ﬂow A compressor driven by an exhaust ﬂow
turbine to charge air into an engine Same as valve
Control ﬂow by restriction; P drops Given
w=0
w=0
w=0
w=0
win
w=0
w==0
w=0
w=0
w=0
wrn,KEup
w=0
w=0
qin,wout
l*’=0
win
w=0
w=0
w=0
w=0
w=0
win,Pup
w==0
w=0
w=0
win
w=0
wout
WmmineWWCV
w=0 Assumption P = constant
P = constant P = constant
P = constant
9 = 0 P = constant
P = constant
P = constant
q = 0 P = constant
P = constant
P = C, q z 0
P : constant
:3 = 0 P = constant P = constant P = constant
P = constant
q = 0 P = constant
4 = 0 Rate equation for entropy
Entropy equation Total entropy change Lost work
Actual boundary work Gibbs relations Solids, Liquids Change in 3 Ideal Gas
Standard entropy Change in 5 Ratio of speciﬁc heats Polyttopic processes Speciﬁc work. tW2=deV_ Wins: Ttis=du+Pdv
Tds=dh~vdP dv=0 _ _ @_ an; E
.32 ChiT} v = constant, T (Function of T)
To
P
s2 3. = 3?" s21 —~ R In F2 (Using Table A? or A.8)
1
T P
S2  .s'; = C1,,0 in ? R111 172 (For constant Cp, CU)
1 1
Tz 1)2
52 s, a CD in? + R In 0—] (For constant Cp, C”)
l
k = CPD/C00 PU" = constant; PV” = constant ﬂzﬂn=ﬂn=§njl
P1 1/2 v2 r. 1w2:l*n(P2l}2 Plvl)=lwn(T2_‘Tl) 71*]
v P
,w2=P1vllnv—?=Rﬂln;%=RTlln~i n=1 The work is moving boundary work w = f P do _ v” .WmaMMWWM... entiﬁable processes 11 = 0; P = constant; lsobaric
n l; T = constant; Isothermal
n — k; s = constant; Isentropic v = constant; Isochoric or isometric MWnM'unrm . (All W, Q can also be rates Q) Heat engine
Heat pump
Refrigerator Factors that make
processes irreversible Carnot cycle Proposition 1
Proposition II Absolute temperature
Real heat engine
Real heat pump Real refrigerator Heat—transfer rates Flow irreversibility Reversible work C.M.
Irreversibility C.M.
Secondlaw efﬁciency Exergy, ﬂow availability
Exergy, stored Exergy transfer by heat
Exergy transfer by ﬂow Exergy rate Eq. Exergy Eq, CM. W 0
WHE =QH—QL; 71H}: :Q—ZE:1_§—;
WHP ZQII—QL; 3H1) =7§izﬁ
_ Qt. _ QL WREF 2 QH — QL; ﬁner — WREF " m Friction, unrestrained expansion (W = 0), Q over AT, mixing, current through a resistor, combustion, or valve
ﬂow (throttle). 1—2 Isothermal heat addition Q” in at T” 2—3 Adiabatic expansion process Tdoes down
3—4 Isothermal heat rejection QL out at T L 4—1 Adiabatic compression process T goes up "any S nmvcrsible same TH: TL "Carnot 1 = "Camotz same TH» TI. 35 : e TH T 77m; = Q—fs nCamotHE =1" 7T; QH T1 BHP — W—HP S BCamotl—l? = TH _: TL
., T BREF = WklEF S BCnmot REF = TH _L TL 9 = CAT i= w'e" — w = q?" = ToSge r52 = Tosgen
T
IWECV = T0032 _ SI) — (U2 .— Ul) + IQZ — T
112 = T00} _ Si) — inTI: = TOISchn 77an law '— Cbgnincd __ (bsupplied _ d>destroyed «supplied damned w= [h Tos+%V2+ng—[ho—Toso+gzol 2
<75 = (e — e0) + P00) — v0) — T0(s — so); (I) = m To
qbtransfer = q 1 — TH d’transfcr = htot I _ him e _ T0(Si _ Se) "d_t'_ Qc.v. Wow. +P0 dt + 2 mil/Ii — 2 rhe¢e — Taggen 'WM Mu. :MWp—u,mcummmiﬂ‘mmm Wh‘lmgﬁn‘ﬂﬁﬁg‘ﬁmmmxmm\=rdmmhmwwmnmmguwmm m.w.. Volume ﬂow rate I" = [V dA = AV (using average velocity) Mass flow rate ti; = fp V tiA = pAV = A‘Wv (using average values)
Flow work rate Wﬂow = PV = :7?th Flow direction From higher P to lower P unless signiﬁcant KB or PE. Instantaneous Process Continuity equation the» = 2 132‘  2 rite
Energy equation EC“ = QC“  WCN. + 2 rigkm ,.  2 mam
TOtal hm: = h + %V2 + = hsmgnation + Steady State
No storage: 152C.“ = 0; EC_V_ == 0
Continuity equation 2 :52; = 2 rite (in = out)
Energy equation ch. + 2 mshmu 2 av. + E Iiichum: (in = 0110
Speciﬁc heat transfer q = gay/2;: (steady state only)
Speciﬁc work w = Wc‘v‘hiz (steady state only) Steadystate single ﬂow q + km 1 = w + hm L, (in = out)
energy equation Transient Process Continuity equation m2 — m1 = E m: — 2 me
Energy equation E2 '" E! = 1Q2 “ {W2 + E mr'hlotf _ 2 mehtote
1 1
E2 '“ El = "12(“2 + EVE + 822) _ "110*! + 3"? + 8'21)
1
hm: e : blot exit average 3 E (hllot el + htot :32) W w M...”— WW" tHIwh—um—‘Wl—W m.. ——u._......_... up“.. .m.mm.muw_——wwm"——wm—MW .an Total energy E = U + KE + KB = mu + 1» mV2 + ng 2
Kinetic energy KE = %m"lf2
Potential energy KE = ng
Speciﬁc energy e = u + % ‘II2 + gZ
Enthalpy h *=‘ u + PU
Twophase mass average at = uf + xufg = (1  x)uf + 3mg )2 = hf+ mfg = (1 — x)hf+ xhg . . =’ 15:25 . z 212
SpeCIﬁe heat, heat capaelty Cu (M1)”: Cp (3T1) Solids and liquids Incompressible, so u = constant “=" of and v very small
C = CU = CF, [Tables A3 and AA (F2 and F.3)]
“2 " “I = 002 F T1)
hz — h, = 242  u} + 00’:  Pl) (Often the second term is small.)
11 = hf+ vf (P — Pm); u E a; (saturated at same .7)
Ideal gas I: = u + Pv = u + RT (only functions of I)
"' ﬂ' = ﬂ :
Cu — dT,CP dT Cu+ R M2 _ “1=JCudT§ Cv(T2 "' Tl) h2  h, = [ders (3,,(23 —— T.) Left—hand side from Table A7 or A.8, middle from Table
A.6 and righthand side from Table A.6 at a TM or from
Table A5 at 25°C
Leﬁhand side from Table F.5 or R6, right—hand side from
TableFA at 77 F Energy equation rate form E = Q — W (rate = + in  out) Energy equation integrated £2 —* E, = lQ2 — .Wz (change = + in — out) I 5 MOVE — Vi) + mg(Zz “ Zn) Multiple masses, states E = mAeA + 271363 + mc ac +    "1(92 ‘ 91) = "3(“2 — “1) + :u umu—awwummmmmnw mtmmmmmn‘nn—n m wax mmqmme‘W7de—memmmmu Rate equation for entropy rate of change = + in — out + generation SW = 2 131,3, — 2 153953 + E Q?“ + Sam 5L“: e 5
Steady state single ﬂow 59 = s,r + ~13 + 336,,
Reversible shaft work w = f U dP + — %V§ + gZi — ch,
i Reversible heat transfer q : Tds = he. — h, — v dP (from Gibbs relation) Bernoulli equation v0”i m P6) + % V? — %V§ + ng — ch, = 0 (v = constant)
Polytropic process work w = —n f 1 (Pene — Pivi) = —nn_Rl (Te  T!) :2 # I
_ _ P8 _ _ Pa _ ve _
w— Pivilnpiw REInPE—RTilnE 11—] E
The work is shaft work w =  I v dP and for ideal gas Isentropic efﬁciencies 17mm = who/W73 (Turbine work is out)
momma, = Wag/WC“ (Compressor work is in)
71me = WP5/Wpac (Pump work is in) “name = A %V§c/A % V3 (Kinetic energy is out)    MAW ummmumm w r m mammmmmmmmmwmmwmwanmumwwmmwwnmmwmmmwm:
mam)“ M. w 43573:."wa . W T
Available work from heat W = Q (I _ 5T3)
H
Reversible ﬂow work with extra q?"
T
from ambient at T0 and q in at TH 936V : T0698 in Si) b q 7:9”
H To
WICVEhimhemTo(s.mse)+q 1“?
H Rankine Cycle Open feedwater heater Closed feedwater heater
Deaerating FWH
Cogeneration Brayton Cycle Compression ratio
Regenerator
Intercooler Jet engine Thrust
Propulsive power Feedwater mixed with extraction steam, exit as saturated
liquid Feedwater heated by extraction steam, no mixing Open feedwater heater operating at Pm to vent gas out
Turbine power is cogenerated with a desired steam supply Pressure ratio rp = Phigh/Plow Dual ﬂuid heat exchanger, uses exhaust ﬂow energy
Cooler between compressor stages, reduces work input
No shaftwork out, kinetic energy generated in exit nozzle
E = 152(Ve — Vi) momentum equation W = F Vaircraﬁ x _ vi)vaircraﬁ Piston Cylinder Power Cycles Compression ratio Displacement (1 cyl.)
Stroke Mean effective pressure Power by I cylinder Refrigeration Cycle Coefﬁcient of performance Combined Cycles Topping, bottoming cycle Cascade system Volume ratio rv = CR = V / V max min
AV “— Vmax — ‘Vmin 1—" mﬁjmax — Umin) : SAcyl
S — 2 Rm, piston travel in compression or expansion.
Pmeff m wnet/ vmax u Umin) 2 Wnet/(Vmax "— Vmin) _ RPM 
W — mwm ——6—6— (times% for fourstroke cycle) The high and lowtemperature cycles
Stacked refrigeration cycles Phases
Phase equilibrium
Multiphase boundaries Equilibrium state
Quality Average speciﬁc volume
Equilibrium surface
Ideal—gas law Universal gas constant
Gas constant Compressibility factor Z
Reduced properties Equations of state Work
Heat Displacement work Speciﬁc work
Power, rate of work Polytropic process Polytropic process work Conduction heat transfer Conductivity Convection heat transfer Convection coefﬁcient Radiation heat transfer
(net to ambient) Rate integration Solid, liquid, and vapor (gas) Tsar» Psat: Uﬁ Ug? vi Vaporization, sublimation, and ﬁision lines:
Figs. 3.5 (general), 3.6 (C02) and 3.7 (water)
Critical point: Table 3.1, Table A2 (F .1) Triple point: Table 3.2 Two independent properties (#1, #2) x = mvap/m (vapor mass fraction) 1. — x = mnq/m (liquid mass fraction) 0 = (1 — 2c)vJ,r + xvg (only two—phase mixture) P—U—T Tables or equation of state
5v = RT PV= mRT = nRT
R = §3145 kJ/krnol K
R = R/M kJ/kg K, Table A5 or M from Table A2
it lbf/lbrn R, Table F4 or M from Table El
PD 3 ZRT Chart for Zin Fig. D.l
P,. = 3 T, = I Entry to compressibility chart PC Tc
Cubic, pressure explicit: Appendix D, Table D.l
B»W~.R: Eq. 3.7 and Table 13.2 for various substances Lee Kesler: Appendix D, Table D3, and Fig. D.l Energy in transfer—mechanical, electrical, and chemical
Energy in transfer, caused by a AT 2 2 2 2
W=der=deV=fffdA=de8
1 l 1 1 mg = W/m (work per unit mass) W = F V = PV = Tm (V displacement rate)
Velocity V = rm, torque T = Fr, angular velocity 2 a)
PV" 2 constant or Pv" = constant 1 [W231MH(P2V2”PIVI) V
.W, = PIV, In}; (ifn =1) l ' _ ._ if
Q — kA (ix
It; (W/m K)
Q = 11A AT
h_(W/m2 K)
Q = eelAU: — Tgmb) (0' = 5.67 x 10*8 W/m2 K4) 1Q2 : [ th ” Qavg A1 ...
View Full
Document
 Spring '08
 Sherif

Click to edit the document details