re: cool tower alternatives SOLAR.KnowledgePublications.com

re: cool tower alternatives
8 dec 2005
then again, we could keep our phoenix house comfy in june (84.1 f with
w = 0.0056) by moving 2470 cfm of 72.9 f daily min outdoor air through
10563 ft^2 of blocks under a 2000 ft^2 slab with gb = 1/2470+1/(2x10563) 
= 2211 btu/h-f of film and fan conductance if 24h(88.2-84.1)425
= (84.1-72.9)2211t, in t = 1.7 hours per day.

or less, with less airflow, if we add water.

how much less?

nick

30 met=1.1'metabolic rate (met)
40 wme=0'external work (met)
60 data 84.1,0.0056,0.5,0.5
70 read tc,wa,vel,clo
80 ta=(tc-32)/1.8'air temp (c)
90 tr=ta'mean radiant temp (c)
100 pa=29.921*3377.2/(1+.62198/wa)'water vapor pressure (pa)
110 def fnps(t)=exp(16.6536-4030.183/(ta+235))'sat vapor pressure, kpa
130 icl=.155*clo'clothing resistance (m^2k/w)
140 m=met*58.15'metabolic rate (w/m^2)
150 w=wme*58.15'external work in (w/m^2)
160 mw=m-w'internal heat production
170 if icl<.078 then fcl=1+1.29*icl else fcl=1.05+.645*icl'clothing factor
180 hcf=12.1*sqr(vel)'forced convection conductance
190 taa=ta+273'air temp (k)
200 tra=tr+273'mean radiant temp (k)
210 tcla=taa+(35.5-ta)/(3.5*(6.45*icl+.1))'est clothing temp
220 p1=icl*fcl:p2=p1*3.96:p3=p1*100:p4=p1*taa'intermediate values
230 p5=308.7-.028*mw+p2*(tra/100)^4
240 xn=tcla/100
250 xf=xn
260 eps=.00015'stop iteration when met
270 xf=(xf+xn)/2'natural convection conductance
280 hcn=2.38*abs(100*xf-taa)^.25
290 if hcf>hcn then hc=hcf else hc=hcn
300 xn=(p5+p4*hc-p2*xf^4)/(100+p3*hc)
310 if abs(xn-xf)>eps goto 270
320 tcl=100*xn-273'clothing surface temp (c)
330 hl1=.00305*(5733-6.99*mw-pa)'heat loss diff through skin
340 if mw>58.15 then hl2=.42*(mw-58.15) else hl2=0'heat loss by sweating
350 hl3=.000017*m*(5867-pa)'latent respiration heat loss
360 hl4=.0014*m*(34-ta)'dry respiration heat loss
370 hl5=3.96*fcl*(xn^4-(tra/100)^4)'heat loss by radiation
380 hl6=fcl*hc*(tcl-ta)'heat loss by convection
390 ts=.303*exp(-.036*m)+.028'thermal sensation transfer coefficient
400 pmv=ts*(mw-hl1-hl2-hl3-hl4-hl5-hl6)'predicted mean vote
410 print tc,wa,vel,clo,pmv

temp      hum rat   air vel   clo       pmv
  
84.1 f    .0056     .5 m/s    .5        .506381

innova airtech instruments has an excellent comfort web site...

http://www.impind.de.unifi.it/impind/didattica/materiale/microclima/innova/thermal.htm