rou_f=0.909*62.4 # density in lbm/ft**3 cp=1.037 # specific heat BTU/(lbm-degree Rankine) v_f=0.204e-5 # viscosity in ft**2/s kf=0.393 # thermal conductivity in BTU/(lbm.ft.degree Rankine) a=6.70e-3 # diffusivity in ft**2/hr Pr=1.099 # Prandtl Number V_v=4.937 # specific volume in ft**3/lbm from superheated steam tables rou_v=1/V_v # vapour density g=32.2 hfg=888.8 # from saturated steam tables Tg=327.81 Tw=325 L=2.0 # length in ft W=3.0 # width in ft z=0.204*10**-5 # distance from entry of plate in ft y=((4*kf*v_f*(Tg-Tw)/3600.0)/(rou_f*g*hfg*(1-(rou_v/rou_f))))**(1/4.0) #let y=delta/z**(1/4) hz=1665 #From Table 10.1 hL=(4/3.0)*hz # at plate end mf=(hL*L*W*(Tg-Tw))/hfg q=mf*hfg Re=(4*mf/3600)/(W*rou_f*v_f) print"The amount of steam condensed is ",round(mf,1),"lbm/h" print"The heat transfer rate is ",round(q,0),"BTU/hr" import matplotlib.pyplot as plt fig = plt.figure() ax = fig.add_subplot(111) x1=[0.0017,0.0018,0.0023,0.0030,0.0035] z1=[2,1.6,0.6,0.3,0.1] x2=[0.0023,0.0022,0.0017,0.0011,0.0006,0] z2=[2,1.6,0.6,0.3,0.1,0] xlabel("d (m)") ylabel("z (m)") plt.xlim((0,0.004)) plt.ylim((2,0)) ax.annotate('(infinity)', xy=(0.0035,0.1)) ax.annotate('(hl=2220)', xy=(0.0005,1.7)) a1=plot(x1,z1) a1=plot(x2,z2)
The amount of steam condensed is 42.1 lbm/h The heat transfer rate is 37429.0 BTU/hr
rou_f=974.0 # density in kg/m**3 cp_1=4196.0 # specific heat in J/(kg*K) v_1=0.364e-6 # viscosity in m**2/s Pr_1=2.22 # Prandtl Number kf=0.668 # thermal conductivity in W/(m.K) a_1=1.636e-7 # diffusivity in m**2/s Vv=1.9364 # specific volume in m**3/kg rou_v=1/Vv # vapor density g=9.81 hfg=2257.06*1000 Tg=100 Tw=60 L=1 OD=0.03340 hD=0.782*((g*rou_f*(1-(rou_v/rou_f))*(kf**3)*hfg)/(v_1*OD*(Tg-Tw)))**(1/4.0) hD=10720 #According to the book import math q=hD*math.pi*OD*L*(Tg-Tw) mf=q/hfg print"The heat flow rate is ",round(q,0),"W" print"The rate at which steam condenses is ",round(mf*3600,0),"kg/hr"
The heat flow rate is 44994.0 W The rate at which steam condenses is 72.0 kg/hr
rou_f=958 # density in kg/m**3 cp_f= 4217 # specific heat in J/(kg*K) v_f= 2.91e-7 # viscosity in m**2/s Pr_f =1.76 # Prandtl Number rou_g=0.596 sigma=0.0589 # surface tension in N/m hfg=2257000 Tw=120.0 Tg=100.0 D=.141 # diameter of pan in m g=9.81 gc=1 Cw=0.0132 # formechanically polished stainless steel from table 10.2 q_A=(rou_f*v_f*hfg)*((g*rou_f*(1-(rou_g/rou_f)))/(sigma*gc))**(0.5)*((cp_f*(Tw-Tg))/(Cw*hfg*Pr_f**1.7))**3 A=math.pi*D**2/4.0 p=q_A*A # power delivered to the water in W mf=q/hfg # water evaporation rate q_cr=0.18*hfg*(sigma*g*gc*rou_f*rou_g**2)**(0.25) print"(a)The power delivered to the water is kW",round(q/1000,2),"KW" print"(b)The water evaporation rate is ",round(mf*3600,2),"kg/h" print"(c)The critical heat flux is ",round(q_cr,0),"W/sq.m"
(a)The power delivered to the water is kW 4.98 KW (b)The water evaporation rate is 7.94 kg/h (c)The critical heat flux is 1521299.0 W/sq.m