C
C
      SUBROUTINE MTCOEF (TX,TB,I,BETA)
C
C     ------------------------------------------------------------
C
C       SUBROUTINE PURPOSE:
C       EVALUATION OF MASS TRANSFER COEFF. FROM CONVECTIVE MASS
C     TRANSFER THEORY.
C
C     ------------------------------------------------------------
C
      INCLUDE 'CMMNW.DAT'
C
      DIMENSION  PTLJ(81),GQ(81)
C
C     PTLJ(81): LENNARD-JONES POTENTIAL.
C     GQ(81): COLLISION INTEGRAL.
C
      DATA
     .    PTLJ/ 0.30,0.35,0.40,0.45,0.50,0.55,0.60,0.65,0.70,
     .          0.75,0.80,0.85,0.90,0.95,1.00,1.05,1.10,1.15,
     .          1.20,1.25,1.30,1.35,1.40,1.45,1.50,1.55,1.60,
     .          1.65,1.70,1.75,1.80,1.85,1.90,1.95,2.00,2.10,
     .          2.20,2.30,2.40,2.50,2.60,2.70,2.80,2.90,3.00,
     .          3.10,3.20,3.30,3.40,3.50,3.60,3.70,3.80,3.90,
     .          4.00,4.10,4.20,4.30,4.40,4.50,4.60,4.70,4.80,
     .          4.90,5.00,6.00,7.00,8.00,9.00,10.0,20.0,30.0,
     .          40.0,50.0,60.0,70.0,80.0,90.0,100.,200.,400./
      DATA
     .    GQ/   2.662,2.476,2.318,2.184,2.066,1.966,1.877,1.798,
     .          1.729,1.667,1.612,1.562,1.517,1.476,1.439,1.406,
     .          1.375,1.346,1.320,1.296,1.273,1.253,1.233,1.215,
     .          1.198,1.182,1.167,1.153,1.140,1.128,1.116,1.105,
     .          1.094,1.084,1.075,1.057,1.041,1.026,1.012,.9996,
     .          .9878,.9770,.9672,.9576,.9490,.9406,.9328,.9256,
     .          .9186,.9120,.9058,.8998,.8942,.8888,.8836,.8788,
     .          .8740,.8694,.8652,.8610,.8568,.8530,.8492,.8456,
     .          .8422,.8124,.7896,.7712,.7556,.7424,.6640,.6232,
     .          .5960,.5756,.5596,.5464,.5352,.5256,.5130,.4644,
     .          .4170/
C
C  ** EVALUATION OF TEMP.-CORRECTED MASS DIFFUSIVITY BY INTERPOLATION.
C
      T1=((TX+TB)/2.0-32.0)*5.0/9.0+273.2
      FCLJ=T1/252.18
      DO 10 J=1,81
         IF (FCLJ.LT.PTLJ(J)) THEN
            GQ1=GQ(J-1)+(GQ(J)-GQ(J-1))*(FCLJ-PTLJ(J-1))/
     .          (PTLJ(J)-PTLJ(J-1))
            GO TO 15
         ENDIF
10    CONTINUE
C
C     D: MASS DIFFUSIVITY IN M**2/SEC.    V: AIRFLOW VELOCITY IN M/S.
C     VISC: KINETIC VISCOSITY IN M**2/S.  RX: HYDROLIC RADIUS IN M.
C     F: FANNING FRICTION FACTOR.         SCH: SCHMIDT NUMBER.
C     RE: REYNOULD NUMBER.
C
15    D=2.56E-5*(1.3291/GQ1)*(T1/298.2)**1.5
      VISC=1.347E-5*(((TX+TB)/2.0+460.0)/492)**1.75
      V=0.3048*ABS(Q(I))*(TB+460.0)/(A(I)*(TR+460.0)*60.0)
      RX=2.0*0.3048*A(I)/O(I)
      SCH=VISC/D
      RE=2.0*V*RX/VISC
      F=(KF(I)/809.0)/2.0
      H=5.0*SCH**0.3333/14.5
      HH1=(1.0+H)*(1.0+H)/(1.0-H+H*H)
      HH2=(2.0*H-1.0)/1.732
      FH=ALOG(HH1)/2.0+ATAN(HH2)*1.732+0.9069
      HH1=14.5*FH*SCH**0.667/3.0
      HH2=(1.0+5.64*SCH)/(6.64*(1.0+0.041*SCH))
      PHI=1.0+SQRT(F/2)*(HH1+5.0*ALOG(HH2)-4.77)
C
C     BETA: MASS TRANSFER COEFF. IN FT/HR.
C
      BETA=3600.0*D*F*RE*SCH/(4.0*PHI*RX*0.3048)
C
      RETURN
      END

