The cooling simulations were performed on each unit with ambient temperatures from 67 to 115 [degrees]F (19.4-46.1[degrees]C) with 5 [degrees]F (2.8[degrees]C) increments from 70[degrees]F (21.1[degrees]C) and indoor wet bulb
temperatures from 49.4 to 77 [degrees]F (9.8-25[degrees]C) with indoor dry bulb temperature from 65 to 85[degrees]F (18.3-29.4[degrees]C).
Therefore, there are trade-offs among wet bulb
effectiveness, cooling capacity and COP at varying re-entry fraction x.
The temperature conditions in the primary kiln were maintained at 121[degrees]C dry bulb and 100[degrees]C wet bulb
. These temperatures correspond to a wood MC of approximately 3.8 percent.
The high year-round load coupled with the increasing approach temperature at lower wet bulbs
results in a cooling tower selection that is oversized for the summer duty.
[t.sub.3] = Entering air wet bulb
temperature degrees Farenheit
Chiller Capacity (tons) 500 Cooling Tower (Condenser) Flow Rate (gpm) 1000 Chiller Efficiency (COP) 6.10 Design Wet Bulb
([degrees]F) 78 Design Approach Temperature ([degrees]F) 4.5 Tower Entering Water Temperature ([degrees]F) 96.5 Tower Leaving Water Temperature ([degrees]F) 82.5 Design Range (Condenser Water [DELTA]T) ([degrees]F) 14 TABLE 2 Cooling tower approach temperature at 60[degrees]F wet-bulb temperature.
The HRF, which is a function of both the outside air wet bulb
and the saturated condensing temperature (SCT or [T.sub.3]), is used to determine the condenser capacity for a given outside wet-bulb temperature and SCT as (Manske et al., 2001):
The maximum cooling potential is measured by the difference of dry bulb temperature of entering air and the wet bulb
temperature (of primary air stream in DEC and DEC/IEC systems; and of the entering secondary air for IEC systems), and is also called wet bulb
Assumed constraints, Design Variables and Performance Indicators Constraints Values Design Variables Symbols Cooler Volume 0.4/14.1 Dry channel air V ([m.sup.3]/ velocity [ft.sup.3]) Design room 25/77 Fraction primary X temperature air re-entering ([degrees]C/ the wet channel [degrees]F) Room cooling 5/1.42 (Dry/wet)channel H load(kW/ton) height Ambient 40/104 Performance dry bulb Indicators temperature ([degrees]C/ [degrees]F) Ambient 20/68 Room based [Q.sub,cap] wet bulb
cooling capacity temperature ([degrees]C/ [degrees]F) Total HX 1.2/3.94 Coefficient of COP height (m/ft) performance HX plate 0.6/1.97 Wet bulb
[[epsilon].sub.wb] length(equal effectiveness to width) (m/ft) Area normalized q cooling generation Table 3.
For equations (1) and (2), the basic assumption is that individual terminal cooling capacity only depends on the terminal wet bulb
temperature and outdoor temperature, and has no interactions with other terminals.
For the sensible cooling design conditions (hottest outdoor dry bulb temperatures, generally accompanied by full solar loading), the mean coincident wet bulb
(MCWB) temperatures range from the low 70s in a few specific locations to the mid 50s in others.