DOE-2 Engineers Manual Version 2.1A - DOE-2.com

There are two types of weather files: solar and normal. Solar files
contain solar radiation data as described above under SOLRAD and DIRSOL.
Normal files contain no solar radiation information. SOLRAD and DIRSOL will
always be zero. Solar radiation is calculated in LOADS from the cloud cover
and cloud type information. The variables RDNCC and BSCC [GLOBAL(21) and
GLOBAL(22)] contain the result of the calculation.
Because the weather variables are packed, i.e., conv;erted to positive
integers and stored with more than one quantity per word, a" decision has been
made on how much precision to keep for each variable. The precisions are
WBT
DBT
PATM
CLDAMT
HUMRAT
DENSTY
ENTHAL
nearest whole of,
nearest whole of,
nearest tenth of an inch in Hg,
nearest integer,
nearest .0001,
nearest .001, and
nearest .5
The weather data is derived from weather tapes suppl ied by the National
Climatic Center. The variables DBT, WBT, PATM, CLDAMT, WNDSPD, ICLTY, and
IWNDDR are directly derived from data on the tapes. When information is
missing for one or more hours, DBT, WBT, PATM, CLDAMT, and WNDSPD are linearly
interpolated from the previously available value to the next available value.
IWNDDR and ICLDTY are assigned the previous available value. WBT is always
forced to be less than or equal to DBT. The other variables are calculated
from the f ormu 1 as "
where
" PPWV
HUMRAT = .622 (PATM _ ppwvj ,
DENSTY = 1/[.754(DBT + 459.7)(1 + 1.606*HUMRAT)]/PATM, and
ENTHAL = .24DBT + (1061 + .444DBT) HUMRAT,
PPwv = the partial pressure of water vapor (in Hg),
(IIL4)
(IIL5)
(III.6)
.662 = the ratio of the molecular weight of water vapor (18.01534) to
the molecular weight of dry air (28.9645),
1.606 = the reciprocal of the ratio .622,
.754 = the factor for converting air and wate!" partial pressure into
inches of mercury (ft2_in/lb_OR)
459.7 = the factor to convert DBT to absolute temperature,
.24 = the specific heat of air (Btu/lb-OF),
II 1.17