# Variables
Di = 10./12; # inside diameter of the coil in ft
x = 7./48; # thickness of coil in ft
ts = 70.5; # Initial temp. of coil in degF
Rm = 12.1; # resistance of coil
e = 0.0024; # Temperature coefficient of coil in degF
i = 0.009; # Initial current in amp
V = 0.1; # Initial Voltage in volts
# Calculations
Rs = V/i; # Initial resistance in ohms
Thm = (Rm/Rs-1)/e; # Mean temperature in degF
Th0 = 1.5*Thm; # Increase in temperature in degF
to = ts+Th0; # Maximum temperature in degF
# Results
print "The maximum temperature of the coil was %.1f degF"%(to);
# note : rounding off error
import math
# Variables
r = 1./4; # radius in inches
to = 300.; # outer surface temperature of cylinder in degF
q0 = 10.; # i2r heat loss in Btu-in**2/hr
k = 10.; # thermal conductivity of the material in Btu/hr-ft-degF
# Calculations and Results
tc = to+(q0*r*r)*12 /(4*k); # temperature at center
delt = tc-to;
print "The temperature diference between center and outer surface is %.2f degF"%(delt);
# Total energy within the cylinder must be transferred to as heat to outer surface
v = math.pi*r**2; # Volume of heatinf element in in**3
q1 = q0*v; # heat flow to outer surface in Btu/sec
tr = -q1*r/(2*k); # derivative of temperature wrt radius
q = q1*12; # Heat flow at the outer surfae in Btu/hr-ft
print " Heat transfer per unit length at the outer surface is %.1f Btu/hr"%(q);