EZ-Set pools seem nice, with the air doughnut around the rim...
12'x36" for $98... We might put a 12'x3' pool in a 16'x16'x8'tall
poly film greenhouse with 5 $7 doubled 1x3 bows on 4' centers...
The pool comes with a filter and a 540 gph pump. With no filter,
it might push water up a few inches above the water level. With
130 F water, it might need a cooling air supply, eg a small hole
in the greenhouse near the ground and another near the peak.
...and cover the pool surface with a 9'x2" foamboard disk supporting
a $60 300'x1" flat pipe spiral heat exchanger in series with the cold
water inlet to a conventional water heater, with 12'x12'x2" of Styrofoam
over that,
....and black fiberglass window screen over that, and poly film over that.
A separate fountain pump might move a little water over the top of the film
to prevent overheating in summertime. Outdoor air with w = 0.0133 in July
in Phila makes Pa = 0.626 "Hg. At 130 F and 100% RH, Pw = 4.74 "Hg, so
a wet square foot might lose 100(Pw-Pa) = 411 Btu/h by evaporation,
more than the peak solar gain.
...with whitewash over (how much of?) the north wall of the greenhouse.
....about 4 feet above the collector, to reflect more winter sun onto it.
20 PI=4*ATN(1)
30 WC=12'N-S collector width (feet)
40 LC=12'E-W collector length (feet)
50 HC=3'collector height (feet)
60 AC=WC*LC'collector area (ft^2)
70 RCC=1'collector cover US R-value
80 RC=RCC/AC'collector-greenhouse thermal resistance (F-h/Btu)
90 WG=16'greenhouse width (feet)
100 LG=16'greenhouse length (feet)
110 HG=8'greenhouse height (feet)
120 FOR HR=6.9 TO 7.1 STEP .1'reflector height above ground (feet)
130 WUC=WC/2+SQR(HG^2-HR^2)'unshaded collector width (feet)
140 AGC=PI*16*16/2+PI*8^2'greenhouse cover area (ft^2)
150 RVG=.8'greenhouse US R-value
160 RG=RVG/AGC'greenhouse-outdoor thermal resistance (F-h/Btu)
170 GHGAIN=.9*(WG*620+HR*1000)*LG/6'Jan gh gain (Btu/h)
180 CGAIN=.9*(WUC*620+.9*(HR-HC)*1000)*LC/6'Jan collector gain (Btu/h)
190 SACGAIN=GHGAIN-CGAIN'sacrificial heater gain (Btu/h)
200 TA=34'outdoor temp (F)
210 TP=130'pond water temp (F)
220 TGAT=TA+SACGAIN*RG'Thevenin gh air temp (F)
230 CLOSS=(TP-TGAT)/(RC+RG)'collector loss (Btu/h)
240 CNET=6*(CGAIN-CLOSS)'net collector gain (Btu/day)
250 PRINT HR,"Jan (Btu/day):"TAB(35);CNET
260 NEXT
reflector
height
6.9' Jan (Btu/day): 57521.07
7.0' Jan (Btu/day): 57581.57
7.1' Jan (Btu/day): 57579.94
With Pi(7^2-5.25^2)3/27 = 7.5 cubic yards of mulch or bags of leaves inside
a 14'x3' welded-wire fence circle (which would provide some pool reinforcing),
16.4K pounds of 120 F water might lose 5dx24h(120-34)(100ft^2/R24+64ft^2/R20)
= 75.8K Btu and provide (16.4K(130-110)-75.8K)/5 = 50.4K Btu/day of hot water
for 5 cloudy days in January.
Nick
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