(71B) Band Emission Factors

[cesarb94]

My first program for the 71B, any comments are appreciated.

This program solves the band emission factors for a blackbody. Good for the calculation of the total absorptivity and emissivity of gray surfaces. It solves Eq. (1.37) from Howell's Thermal Radiation Heat Transfer, 10th Ed.

EMISSION
10 REAL K,P,S,T,L,U,W,C
20 SHORT F
30 INTEGER M
40 C=14387.77 !2nd Planck's Constant in [µm.K]
50 F1=0
60 F0=0

70 INPUT "Temperature [K]: ", STR$(T);T
80 INPUT "From [um]: ", STR$(L);L
90 INPUT "To [um]: ", STR$(U);U
100 DISP "Calculating..."
110 F$="F(" & STR$(L) & CHR$(62) & STR$(U) & ")= "

120 'LWR': IF L=0 THEN GOTO "UPR"
130 CALL CHANG(L,F0,C,T)
140 'UPR': CALL CHANG(U,F1,C,T)
150 F=F1-F0
160 DISP F$ & STR$(F)

170 SUB CHANG(W,F,C,T)
180 P=0
190 M=0
200 K=C/(W*T)
210 FOR M=1 TO 10
220 S=EXP(-M*K)/M*(K^3+3*K^2/M+6*K/M^2+6/M^3)
230 P=P+S
240 IF S<1E-16 THEN M=10
250 NEXT M
260 F=15*P/PI^4
270 END SUB

Testing (from the book):
Temperature: 3600 K
Lower Bound: 0.4 µm
Upper Bound: 0.7 µm
Result: 0.15605