The form of (10) justifies a linear combination of dry-bulb and dewpoint temperatures as an approximation to wet-bulb temperature, for the assumptions of relatively small wet-bulb depression
and relatively moist conditions.
This type of economizer can be beneficial in areas of high wet-bulb depression
, such as desert regions.
For example, at the relatively modest wet-bulb depression
condition of 26.
c) IEC heat exchangers that use a portion of the leaving, conditioned dry air as scavenger air in an attempt to increase the Wet-Bulb Depression
Efficiency (WBDE), but at the expense of increased size and/or power consumption.
Of the other variables measured, knot area, ring count, ring angle, initial MC, heartwood percentage, wet-bulb depression
, and wet-bulb temperature were insignificant at the 95 percent confidence level and were not included in the final correlation.
Evaporative precooling (Figure 1) significantly enhances heat rejection potential when a wet-bulb depression
(difference between the dry-bulb and wet-bulb temperature) exists of 10[degrees]F (5.
But in humid climates, when wet-bulb temperatures are higher and the wet-bulb depression
is small, the amount of cooling obtained is reduced considerably.
A previous report (Simpson 2001) showed that the heat conduction equations developed by MacLean (1932) work well in calculating heating time estimates when the heating medium is saturated steam (in practice, a wet-bulb depression
of no more than about 2[degrees] to 3[degrees]F (1.
The measured wet-bulb temperature is increased by a percentage of the thermodynamic wet-bulb depression
and the deviation is larger at low surrounding air velocities.
Among the three mills, all drying schedules started between 65[degrees] and 71[degrees]C with a 5[degrees]C wet-bulb depression
and ended between 79[degrees] and 85[degrees]C with a 16[degrees] to 21[degrees]C wet-bulb depression
Shifting to a higher wet-bulb depression
may cause more drying defects, such as surface checks.
Non-significant variables that were eliminated from the model included wood temperature, dry-bulb temperature, kiln vapor pressure, wet-bulb depression
, and wood MC.