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

The exact same procedure is used to generate a daily cycle for dewpoint
temperature from the user's input DEWPT-HI, DEWPT-LO, DHOLR-HI, and DHOUR-LO.
All other variables are held constant at the values input by the user.
The user can generate a constant dry-bulb or dewpoint cycle by inputting equal
values for DRYBULB-HI and DRYBULB-LO on DEWPT-HI and DEWPT-LO.
The humidity ratio and enthalpy are calculated by Eqs. (111.4) and (111.5)
of the previous section. The vapor pressure is the saturated vapor pressure
at the dewpoint, again calculated by the Goff formula (Ref. 1, pg 5.2). The
pressure used is the design pressure,
PATMDS = 29.92E(-.0000368 * BALT1T),
where BALTIT is the altitude input by the ALTITUDE keyword in the BUILDING­
LOCATION command. The user must beware of inputting data that will generate
relative humidities greater than 100 per cent. No checks are made for this
condition in the design day algorithm.
Finally, the hourly wet-bulb temperature is calculated from the enthalpy
and PATMDS using the procedure given on pages 5.4 and 5.5 of Ref. 1. The
expl icit algorithm is given on page 103, Ref. 2.
II 1.20