import math
#Operating Conditions
Ts = 118+273. ;#[K] Surface Temperature
Tsat = 100+273. ;#[K] Saturated Temperature
D = .3 ;#[m] Diameter of pan
g = 9.81 ;#[m^2/s] gravitaional constant
#Table A.6 Saturated water Liquid Properties T = 373 K
rhol = 957.9 ;#[kg/m^3] Density
cp = 4.217*math.pow(10,3) ;#[J/kg] Specific Heat
u = 279*math.pow(10,-6) ;#[N.s/m^2] Viscosity
Pr = 1.76 ;# Prandtl Number
hfg = 2257*math.pow(10,3) ;#[J/kg] Specific Heat
si = 58.9*math.pow(10,-3) ;#[N/m]
#Table A.6 Saturated water Vapor Properties T = 373 K
rhov = .5956 ;#[kg/m^3] Density
Te = Ts-Tsat;
#calculations
#From Table 10.1
C = .0128;
n = 1.;
q = u*hfg*math.pow(g*(rhol-rhov)/si,.5)*math.pow((cp*Te/(C*hfg*math.pow(Pr,n))),3);
qs = q*math.pi*D*D/4.; #Boiling heat transfer rate
m = qs/hfg; #Rate of evaporation
qmax = .149*hfg*rhov*math.pow(si*g*(rhol-rhov)/(rhov*rhov),.25); #Critical heat flux
#results
print '%s %.2f %s' %("\n Boiling Heat transfer rate = ",qs/1000. ,"kW")
print '%s %d %s' %("\n Rate of water evaporation due to boiling =",m*3600 ,"kg/h")
print '%s %.2f %s' %("\n Critical Heat flux corresponding to the burnout point =",qmax/math.pow(10,6) ,"MW/m^2");
#END
import math
#Operating Conditions
Ts = 255+273. ;#[K] Surface Temperature
Tsat = 100+273. ;#[K] Saturated Temperature
D = 6*math.pow(10,-3) ;#[m] Diameter of pan
e = 1 ;# emissivity
stfncnstt=5.67*math.pow(10,(-8)) ;# [W/m^2.K^4] - Stefan Boltzmann Constant
g = 9.81 ;#[m^2/s] gravitaional constant
#Table A.6 Saturated water Liquid Properties T = 373 K
rhol = 957.9 ;#[kg/m^3] Density
hfg = 2257*math.pow(10,3) ;#[J/kg] Specific Heat
#Table A.4 Water Vapor Properties T = 450 K
rhov = .4902 ;#[kg/m^3] Density
cpv = 1.98*math.pow(10,3) ;#[J/kg.K] Specific Heat
kv = 0.0299 ;#[W/m.K] Conductivity
uv = 15.25*math.pow(10,-6) ;#[N.s/m^2] Viscosity
#calculations
Te = Ts-Tsat;
hconv = .62*math.pow((kv*kv*kv*rhov*(rhol-rhov)*g*(hfg+.8*cpv*Te)/(uv*D*Te)),.25);
hrad = e*stfncnstt*(math.pow(Ts,4)-math.pow(Tsat,4))/(Ts-Tsat);
#From eqn 10.9 h^(4/3) = hconv^(4/3) + hrad*h^(1/3)
#Newton Raphson
h=250.; #Initial Assumption
while 1>0 :
f = math.pow(h,(4./3.)) - (math.pow(hconv,(4./3.)) + math.pow(hrad*h,(1./3.)));
fd = (4./3.)*math.pow(h,(1./3.)) - (1./3.)*hrad*math.pow(h,(-2./3.));
hn=h-f/fd;
z=math.pow(hn,(4./3.)) - (math.pow(hconv,(4./3.)) + math.pow(hrad*hn,(1./3.)))
if z < .01:
break;
h=hn;
q = h*math.pi*D*Te; #power dissipation
#results
print '%s %d %s' %("\n Power Dissipation per unith length for the cylinder, qs= ",q,"W/m");
print '%s' %("The answer is a bit different due to rounding off error")
#END
import math
#Operating Conditions
Ts = 50+273. ;#[K] Surface Temperature
Tsat = 100+273. ;#[K] Saturated Temperature
D = .08 ;#[m] Diameter of pan
g = 9.81 ;#[m^2/s] gravitaional constant
L = 1 #[m] Length
#Table A.6 Saturated Vapor Properties p = 1.0133 bars
rhov = .596 ;#[kg/m^3] Density
hfg = 2257*1000. ;#[J/kg] Specific Heat
#Table A.6 Saturated water Liquid Properties T = 348 K
rhol = 975. ;#[kg/m^3] Density
cpl = 4193. ; #[J/kg.K] Specific Heat
kl = 0.668 ;#[W/m.K] Conductivity
ul = 375*math.pow(10,-6) ;#[N.s/m^2] Viscosity
#calculations
uvl = ul/rhol ;#[N.s.m/Kg] Kinematic viscosity
Ja = cpl*(Tsat-Ts)/hfg;
hfg2 = hfg*(1+.68*Ja);
#Equation 10.43
Re = math.pow((3.70*kl*L*(Tsat-Ts)/(ul*hfg2*math.pow((uvl*uvl/g),.33334))+4.8),.82); #Reynolds number
#From equation 10.41
hL = Re*ul*hfg2/(4*L*(Tsat-Ts)); #Transfer coefficient
q = hL*(math.pi*D*L)*(Tsat-Ts); #Heat transfer rate
m = q/hfg; #Rate of condensation
#Using Equation 10.26
delta = math.pow((4*kl*ul*(Tsat-Ts)*L/(g*rhol*(rhol-rhov)*hfg2)),.25);
#results
print '%s %.2f %s %.4f %s' %("\n Heat Transfer Rate = ",q/1000.,"kW and Condensation Rates=",m," kg/s");
print '%s %.3f %s %.2f %s' %("\n And as del(L)", delta*1000,"<< (D/2)", D/2. ,"m use of vertical cylinder correlation is justified");
#END
import math
#Operating Conditions
Ts = 25+273. ;#[K] Surface Temperature
Tsat = 54+273. ;#[K] Saturated Temperature
D = .006 ; #[m] Diameter of pan
g = 9.81 ;#[m^2/s] gravitaional constant
N = 20 # No of tubes
#Table A.6 Saturated Vapor Properties p = 1.015 bar
rhov = .098 ;#[kg/m^3] Density
hfg = 2373*1000. ;#[J/kg] Specific Heat
#Table A.6 Saturated water Liquid Properties Tf = 312.5 K
rhol = 992. ;#[kg/m^3] Density
cpl = 4178. ;#[J/kg.K] Specific Heat
kl = 0.631 ; #[W/m.K] Conductivity
ul = 663*math.pow(10,-6) ; #[N.s/m^2] Viscosity
#calculations
Ja = cpl*(Tsat-Ts)/hfg;
hfg2 = hfg*(1+.68*Ja); #Coefficient of condensation
#Equation 10.46
h = .729*math.pow((g*rhol*(rhol-rhov)*kl*kl*kl*hfg2/(N*ul*(Tsat-Ts)*D)),.25);
#Equation 10.34
m1 = h*(math.pi*D)*(Tsat-Ts)/hfg2; #Average condensation rate
m = N*N*m1; #Rate per unit length
#results
print '%s %.3f %s' %("\n For the complete array of tubes, the condensation per unit length is",m ," kg/s.m");
#END