Subject: A drumwall solar heater

From: [email-masked] (Nick Pine)
Date: 17 Nov 1994 18:32:59 -0500

Used 55 gallon drums are a growing resource ("Our only growing resource
is trash" :-) The local bakery says I can have all I want, free. They say
that 55 gallon steel drums are hard to get rid of, now that trash burning
in drums is illegal. Here is a possible design for a drumwall that could be
used as a solar water heater.

It would use 30 drums, stacked up horizontally between a couple of
railroad ties, as a 16' long and 9' high x 3' thick wall. 13,200 pounds
of water :-)

The numbers below indicate drum water temperatures in degrees F, from a small
simulation using average Philadelphia weather conditions in January
(ambient temp, 32 degrees, 1200 Btu/day of sun on a south-facing wall,
T^4 heat loss) while extracting 79K Btu/day of domestic hot water from
the wall, using 4 food-grade, *plastic-lined* drums plumbed in series, on
the top row, pressurized with cold water on the way to the input of an
electric hot water in a house.

To continue the low-cost recycling motif, it might be nice to insulate the back
of the wall with bags of leaves, and put it inside a sunspace made from
2 x 4's and polyethylene film or Dynaglas corrugated polycarbonate
((408)-997-6100), with a large foil-foam solar shutter (or several smaller
shutters) that automatically opens and closes on sunny days (see related
posting.)

Nick

10 'estimate water temps for drumwall
20 N=8'number of drums in base row
30 ND=5*(N+N-4)/2'total number of drums
40 DIM T(5,N)'array of drum water temperatures
50 OPEN "drumout" FOR OUTPUT AS #1
60 'find steady-state temps
70 FOR R=1 TO 5'1 is top row, 5 is bottom row...
80 FOR D=1 TO R+N-5'1 is west drum in row...
90 T(R,D)=170'initialize drum temps
100 NEXT:NEXT
110 AREA=2*N*9'effective area of drumwall surface, a little bigger than actual
120 SUNH=1.5*AREA*1100/ND/24'hourly sun input per drum, inc. by shutter refl.
130 UH=79200!/24'heat output of drumwall (6 10 m, 3 gpm, 110 showers/day)
140 GLOSSF=1.74E-09*6*AREA/ND/24'factor for heat lost thru glazing per drum
150 AMRADF=(32+459)^4'factor for radiation from surroundings to drumwall
160 CP=55*8'thermal mass of a drum full of water
170 CLS
180 HMAX=240
200 PRINT #1,"Charging mode, with sun..."
205 PRINT "Charging mode, with sun..."
210 GOSUB 690
220 FOR H=1 TO HMAX'hours of use
225 TECON=0'initialize total convection heat from below
230 LB=UH/(T(1,1+N-5)-55)'water moved thru system per hour
240 GOSUB 640
250 'adjust top drum row temperatures
260 FOR D=1 TO 1+N-5'drum number in top row
270 TD=T(5,1)-T(1,D)'temp diff between top drum and lower drums
280 IF TD>0 THEN ECON=TD*25 ELSE ECON=0'convection heat from below
290 TECON=TECON+ECON'accumulate total convection heat
300 HEATFLOW=SUNH+ECON-((T(1,D)+459)^4-AMRADF)*GLOSSF
310 T(1,D)=T(1,D)+HEATFLOW/CP'adjust top row drum temp
320 NEXT D
330 ECONA=TECON/(ND-(1+N-5))'heatflow to top row from average drum
340 FOR R=2 TO 5'adjust bottom row temps
350 FOR D=1 TO R+N-5
360 HEATFLOW=SUNH-ECONA-((T(R,D)+459)^4-AMRADF)*GLOSSF
370 T(R,D)=T(R,D)+HEATFLOW/CP
380 NEXT D
390 NEXT R
400 IF H MOD 48 = 0 THEN GOSUB 690'print drum temp array
410 NEXT H
420 PRINT #1,
425 PRINT
430 PRINT #1,"Storage mode, with no sun..."
435 PRINT "Storage mode, with no sun..."
440 PRINT #1,
445 PRINT
450 FOR H=1 TO 168'hours of use
455 TECON=0'initialize total convection heat from below
460 'adjust top drum row temperatures
480 LB=UH/(T(1,4)-55)'water moved thru system per hour
485 GOSUB 640
490 FOR D=1 TO 1+N-5'drum number in top row
500 TD=T(5,1)-T(1,D)'temp diff between top drum and lower drums
510 IF TD>0 THEN ECON=TD*25 ELSE ECON=0'convection heat from below
520 TECON=TECON+ECON'accumulate total convection heat
530 T(1,D)=T(1,D)+ECON/CP
540 NEXT D
550 IF H MOD 24 = 0 THEN GOSUB 690'print drum temp array
560 ECONA=TECON/(ND-(1+N-5))'heatflow to top row from average drum
570 FOR R=2 TO 5'adjust bottom row temps
580 FOR D=1 TO R+N-5
590 T(R,D)=T(R,D)-ECONA/CP
600 NEXT D
610 NEXT R
620 NEXT H
630 END
640 T(1,1)=(LB*55+(CP-LB)*T(1,1))/CP'move 55 degree water into top row
650 T(1,2)=(LB*T(1,1)+(CP-LB)*T(1,2))/CP'move water from top drum 1-->2
660 T(1,3)=(LB*T(1,2)+(CP-LB)*T(1,3))/CP'move water from top drum 2-->3
670 T(1,4)=(LB*T(1,3)+(CP-LB)*T(1,4))/CP'move water from top drum 2-->4
680 RETURN
690 PRINT #1,
700 PRINT
710 PRINT #1,"Day:";H/24
720 PRINT"Day:";H/24
730 FOR RS=1 TO 5'display drum temperatures
740 PRINT #1,TAB(3*(5-RS)+1);
750 PRINT TAB(3*(5-RS)+1);
760 FOR P=1 TO RS+N-6
770 PRINT #1,INT(T(RS,P)+.5);TAB(3*(5-RS)+1+6*P)
780 PRINT INT(T(RS,P)+.5);TAB(3*(5-RS)+1+6*P)
790 NEXT P
800 PRINT #1,INT(T(RS,RS+N-5)+.5)
810 PRINT INT(T(RS,RS+N-5)+.5)
820 NEXT RS
830 RETURN

Charging mode, with sun...
 
Day: 0 
             170   170   170   170 
          170   170   170   170   170 
       170   170   170   170   170   170 
    170   170   170   170   170   170   170 
 170   170   170   170   170   170   170   170 
 
Day: 2 
             117   146   161   170 
          174   174   174   174   174 
       174   174   174   174   174   174 
    174   174   174   174   174   174   174 
 174   174   174   174   174   174   174   174 
 
Day: 4 
             117   146   161   169 
          175   175   175   175   175 
       175   175   175   175   175   175 
    175   175   175   175   175   175   175 
 175   175   175   175   175   175   175   175 
 
Day: 6 
             117   146   162   170 
          175   175   175   175   175 
       175   175   175   175   175   175 
    175   175   175   175   175   175   175 
 175   175   175   175   175   175   175   175 
 
Day: 8 
             117   147   162   170 
          176   176   176   176   176 
       176   176   176   176   176   176 
    176   176   176   176   176   176   176 
 176   176   176   176   176   176   176   176 
 
Day: 10 
             118   147   162   171 
          176   176   176   176   176 
       176   176   176   176   176   176 
    176   176   176   176   176   176   176 
 176   176   176   176   176   176   176   176 

Storage mode, with no sun...
 
Day: 1 
             110   138   154   163 
          170   170   170   170   170 
       170   170   170   170   170   170 
    170   170   170   170   170   170   170 
 170   170   170   170   170   170   170   170 
 
Day: 2 
             105   131   147   156 
          164   164   164   164   164 
       164   164   164   164   164   164 
    164   164   164   164   164   164   164 
 164   164   164   164   164   164   164   164 
 
Day: 3 
             100   125   140   149 
          157   157   157   157   157 
       157   157   157   157   157   157 
    157   157   157   157   157   157   157 
 157   157   157   157   157   157   157   157 
 
Day: 4 
             95    118   132   141 
          151   151   151   151   151 
       151   151   151   151   151   151 
    151   151   151   151   151   151   151 
 151   151   151   151   151   151   151   151 
 
Day: 5 
             91    111   125   133 
          144   144   144   144   144 
       144   144   144   144   144   144 
    144   144   144   144   144   144   144 
 144   144   144   144   144   144   144   144 
 
Day: 6 
             86    104   117   125 
          138   138   138   138   138 
       138   138   138   138   138   138 
    138   138   138   138   138   138   138 
 138   138   138   138   138   138   138   138 
 
Day: 7 
             81    97    109   117 <-- water temp supplied to house
          131   131   131   131   131        after 7 days without sun
       131   131   131   131   131   131 
    131   131   131   131   131   131   131 
 131   131   131   131   131   131   131   131