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re: gfx vs home brew
16 apr 2006
solar flare wrote:
>well the efficiency of heat exchange factor is not the only
>efficiency. a purchased and installed product at 5% efficiency is much
>more economical than a well designed, thought out, project that will
>be implemented sometime after getting a 'round tuit
le mieux est l'ennemi du bien. i'm better at thinking up things
than getting round tuits.
> efficiency of installation ease.
> efficiency of installation time.
> efficiency of product parts and pieces aquisition
i can relate to that, having spent about 40 hours in the last 2 weeks
visiting various plumbing supply stores. it's been fun learning names
of fittings, like "bullnose t" and "dismukes crampon lifter."
> efficiency of marriage after the home space displacement.
spouses care a lot more about what's on the lawn
or in the living room than what's in the basement.
> efficiency of trial and error costs.
it might be nice to build more than one, with careful directions at
http://builditsolar.com
> efficiency of maintenance.
and only empty the crud once a year, using a hose instead of a toothbrush.
> efficiency of computer time arguing about imaginary issues.
some issues are more important than others, eg daestrom's.
> efficiency of home resale after the newfangled frankenstein
>paraphenalia is seen.
this leads me to make things easy to remove.
>"robert gammon" wrote:
>
>> solar flare wrote:
>> > gfx nick
>> > efficiency 6 7
>> > price 5 3
>> > convenience 9 1
>> > wife likes 6 0
>> > ----------------------
>> > total score 26 11
>> >
>> great scoring system.
nah. efficiency should be 8 vs 7, a lower price should give me more
vs fewer points, convenience is tbd, and wives may like saving more
money, or having more to spend in other directions.
20 upipe=78.5'u-value of 10' section of pipe (btu/h-f)
30 cfresh=1.25*8.33'thermal capacitance of 10' of fresh water (btu/f)
40 vgrey=10*3.14159*(2/12)^2'volume of 10' of greywater (ft^3)
50 cgrey=vgrey*62.33-cfresh'thermal capacitance of 10' of greywater (btu/f)
60 for shower = 1 to 1000'simulate showers
70 for m=0 to 359'simulate 10 min shower + 350 min rest
80 if m>9 goto 200'rest vs shower
90 if shower <1000 goto 120
100 rheat=rheat+1.25*8.33*(100-tf(0))'reheat energy
105 gloss=gloss+1.25*8.33*(tg(9)-55)'greywater heat loss
110 print 300+m;"'";m,tf(0),rheat,tg(9),gloss
120 tf(0)=tf(1)'move fresh water up
130 tg(0)=(100*cfresh+tg(0)*(cgrey-cfresh))/cgrey'move greywater in at the top
140 for s=1 to 8'pipe section (9<->fresh water in and greywater out)
150 tf(s)=tf(s+1)'move fresh water up
160 tg(s)=(tg(s-1)*cfresh+tg(s)*(cgrey-cfresh))/cgrey'move greywater down
170 next s
180 tf(9)=55'move cold water in at the bottom
190 tg(9)=(tg(8)*cfresh+tg(9)*(cgrey-cfresh))/cgrey'move greywater down
200 for s=0 to 9'rest
210 heatflow=(tg(s)-tf(s))*upipe/60'heatflow into fresh water (btu)
220 tf(s)=tf(s)+heatflow/cfresh'new fresh temp (f)
230 tg(s)=tg(s)-heatflow/cgrey'new grey temp (f)
240 next s
250 next m
260 next shower
280 showergy=1.25*10*8.33*(100-55)
290 print rheat,showergy,1-rheat/showergy
0 94.56091 56.6345 71.68895 173.7736
1 92.93514 130.1973 72.0242 351.0381
2 91.38136 219.9389 72.44145 532.6472
3 89.96538 324.4244 72.83433 718.3472
4 88.72086 441.8685 73.20448 907.9012
5 87.6472 570.492 73.55341 1101.089
6 86.72784 708.6885 73.88255 1297.703
7 85.94302 855.0568 74.19321 1497.553
8 85.27464 1008.385 74.4866 1700.457
9 84.70704 1167.623 74.76389 1906.248
1167.623 4685.625 .7508075
this is confusing. the greywater output seems to warm during the course of
a shower, but i wouldn't expect that in a real system with 100' of 4" pipe.
nick
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