Heating - Heat Emitters - Page 1 2 3 4 
Syllabus Area - High
temperature and medium temperature hot water systems
Question:
Design a suitable pressurised heating system for the attached
building.
Provide a drawing of the plant and controls.
Show on the drawings pressure distribution through the system.
Answer:
In order to heat the factory space &
office area shown on the drawing I must first decide on my heating medium.
After consultation with the reference table
and as shown previously on this assignment and after thought on past and
present experiences I have decided upon using a medium temperature hot water
heated ceiling panel for the factory area and radiators with trv.’s
(thermostatic radiator valves) for the office space.
My first action is to calculate the heat loss incurred by the factory area and
offices.
I will use a figure of 35 W/m3 heat loss as my base rate for the
heat loss calculations.
Factory 30 x 24 x 5 (height assumed) x 35
=126000 watts or 126 kW
Toilet1 6 x 3 x 2.5 x35 =1575 watts or 1.6 kw
Toilet 2 6 x 3 x 2.5 x35 =1575 watts or 1.6 kW
Office 1 8 x 6 x 2.5 x 35 =4200 watts or 4.2 KW
Office 2 8.7 x 6 x 2.5 x 35 =4568 watts or 4.56 kW
The factory circuit will be medium temperature operating at 120oC flow and
110oC return.
The pipe carries 126 kW of heat.
126 / 42 = 3kg/s from this flow rate I can
pipe size
Each panel carries 31.5 kW
31.5/42 = 0.75kg/s flow rate
From the table below I can transform these
flow rate into pipe sizes.
Factory main size = 65mm with a pressure drop
of 98 pa/m
Size to each panel = 40mm with a pressure
drop of 86 pa/m
The table below was extracted from the
Frenger web site giving actual
|
Heat Emission W/Metre Length |
|||||||||||
|
Mean Water |
Room Temp |
2T |
3T |
4T |
5T |
6T |
|
|
|
|
|
|
76.5 |
13 |
252 |
377 |
503 |
628 |
753 |
|
|
|
|
|
|
|
16 |
238 |
357 |
476 |
594 |
712 |
|
|
|
|
|
|
|
19 |
224 |
336 |
448 |
560 |
672 |
|
|
|
|
|
|
|
21 |
216 |
324 |
432 |
540 |
648 |
|
|
|
|
|
|
80 |
13 |
268 |
402 |
536 |
670 |
804 |
|
|
|
|
|
|
|
16 |
254 |
382 |
509 |
635 |
764 |
|
|
|
|
|
|
|
19 |
240 |
351 |
480 |
601 |
721 |
|
|
|
|
|
|
|
21 |
231 |
346 |
462 |
578 |
693 |
|
|
|
|
|
|
90 |
13 |
315 |
473 |
630 |
788 |
945 |
|
|
|
|
|
|
|
16 |
301 |
451 |
602 |
752 |
901 |
|
|
|
|
|
|
|
19 |
287 |
430 |
574 |
716 |
860 |
|
|
|
|
|
|
|
21 |
276 |
414 |
552 |
660 |
828 |
|
|
|
|
|
|
100 |
13 |
364 |
546 |
728 |
910 |
1091 |
|
|
|
|
|
|
|
16 |
350 |
524 |
699 |
874 |
1049 |
|
|
|
|
|
|
|
19 |
334 |
502 |
669 |
837 |
1004 |
|
|
|
|
|
|
|
21 |
324 |
486 |
648 |
810 |
972 |
|
|
|
|
|
|
110 |
13 |
415 |
623 |
830 |
1039 |
1246 |
|
|
|
|
|
|
|
16 |
400 |
600 |
800 |
1000 |
1200 |
|
|
|
|
|
|
|
19 |
384 |
576 |
768 |
960 |
1152 |
|
|
|
|
|
|
|
21 |
373 |
559 |
745 |
932 |
1118 |
|
|
|
|
|
|
120 |
13 |
466 |
699 |
933 |
1166 |
1399 |
|
|
|
|
|
|
|
16 |
452 |
677 |
904 |
1129 |
1354 |
|
|
|
|
|
|
|
19 |
436 |
654 |
871 |
1089 |
1308 |
|
|
|
|
|
|
|
21 |
423 |
635 |
846 |
1058 |
1270 |
|
|
|
|
|
|
130 |
13 |
525 |
787 |
1050 |
1311 |
1574 |
|
|
|
|
|
|
|
16 |
504 |
756 |
1009 |
1261 |
1512 |
|
|
|
|
|
|
|
19 |
488 |
731 |
975 |
1219 |
1462 |
|
|
|
|
|
|
|
21 |
476 |
714 |
952 |
1190 |
1428 |
|
|
|
|
|
|
140 |
13 |
574 |
861 |
1148 |
1436 |
1722 |
|
|
|
|
|
|
|
16 |
558 |
836 |
1118 |
1394 |
1673 |
|
|
|
|
|
|
|
19 |
542 |
813 |
1086 |
1357 |
1627 |
|
|
|
|
|
|
|
21 |
529 |
794 |
1059 |
1324 |
1588 |
|
|
|
|
|
|
150 |
13 |
629 |
943 |
1258 |
1571 |
1886 |
|
|
|
|
|
|
|
16 |
612 |
919 |
1224 |
1531 |
1838 |
|
|
|
|
|
|
|
19 |
595 |
893 |
1190 |
1488 |
1786 |
|
|
|
|
|
|
|
21 |
586 |
878 |
1171 |
1464 |
1757 |
|
|
|
|
|