daestrom wrote:

While I agree that 'batch' flows that do not fully purge your apparatus will
give you some improvements, we haven't seenn any of your 'numbers' for that.

Here are some numbers for that...

Oops. Fixing lines 100, 130, and 160 improves the effectiveness to 88%.

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 M10 GOTO 170'rest vs shower
90 TF(0)=TF(1)'move fresh water up
100 TG(0)=(100*CFRESH+TG(0)*(CGREY-CFRESH))/CGREY'move greywater in at the top
110 FOR S=1 TO 8'pipe section (9-fresh water in and greywater out)
120 TF(S)=TF(S+1)'move fresh water up
130 TG(S)=(TG(S-1)*CFRESH+TG(S)*(CGREY-CFRESH))/CGREY'move greywater down
140 NEXT S
150 TF(9)=55'move cold water in at the bottom
160 TG(9)=(TG(8)*CFRESH+TG(9)*(CGREY-CFRESH))/CGREY'move greywater down
170 FOR S=0 TO 9'rest
180 HEATFLOW=(TG(S)-TF(S))*UPIPE/60'heatflow into fresh water (Btu)
190 TF(S)=TF(S)+HEATFLOW/CFRESH'new fresh temp (F)
200 TG(S)=TG(S)-HEATFLOW/CGREY'new grey temp (F)
210 NEXT S
220 NEXT M
230 NEXT SHOWER
240 FOR S=3 TO 9'results
250 PRINT 300+S;"'";S;TF(S),TG(S)
260 NEXT S
270 E=(TF(0)-55)/(100-55)
280 PRINT 410;"'";E

pipe fresh water greywater
section temp (F) temp (F)

0 94.53323 94.53326
1 92.54844 92.54847
2 90.32916 90.32919
3 87.93309 87.93311
4 85.42671 85.42674
5 82.85161 82.85163
6 80.22588 80.2259
7 77.55527 77.55529
8 74.8424 74.84241
9 72.08957 72.0896

effectiveness

..8785163

Nick