Meting van de koelcapaciteit van een container onder Zuiditaliaanse klimaatsomstandighede

Beek, G., van

Name not available

Heat transmission of a reference and practical container under subtropical conditions

Wageningen Yield 

S P R E N G E R I N S T I T U U T 
Haagsteeg 6 , 6708 PM Wageningen 
T e l . : O837O-I9OI3 
(Publikatie uitsluitend met 
toestemming van de diveeteiœ) 
RAPPORT'NO. 2217 
!r. G. van Beek 
HEAT TRANSMISSION OF A REFERENCE AND 
PRACTICAL CONTAINER UNDER SUBTROPICAL 
CONDITIONS 
Uitgebracht aan de directeur van het Sprenger Instituut 
Project no. 17 
-1-
1. Introduction 
Under tropical and subtropical conditions the heat of transmission through in-
sulated container walls is influenced by radiation. The cooling capacity of the 
container must be chosen conformable to the maximum heat load. This report com-
pares the transmission of a reference and a practical container under South-
Italian conditions. 
2. Container 
The reference container has insulated walls all over, with a K-value of 
0,^ W/(m2.K). The practical container has top and bottom k-values of 0,1, side 
walls 0,7 and front and rear wall 0,A. The length, width and height are respec-
tively 12 m, 2,5 m and 2,5 m. The inside temperature is -20 C. The orientation 
of the container is north-south (rear - front) and north-west/south-east. 
3. Ambient climate 
The air velocity around the container gives a convective heat transfer of 
15 W/(m27K). The adsorption coefficient is 1 because the radiation has already 
been corrected for the reflection. Table 6 shows the climate conditions. 
k. Method of calculation 
To calculate the temperature inside the wall a step-by-step numerical solution 
was used of the Binder-Schmidt type (see Arpaci, Conduction heat transfer,. 
Add?son-West ley, Reading, 1966, p„ 515). 
The surface temperature was calculated every time step from a heat balance over 
the surface. The surface temperature equal Is: 
T -, = (J + a : T . + - L T )/(a + •£-) • 
surf air Ax 1 Ax 
where 
J W/m2 radiation 
a W/(m2« K) heat transfer (convective) 
T . C air temperature 
ai r 
W/(m • K) thermal conductivity of insulation material 
Ax m distance from surface to first nodal point 
T. C temperature of first nodal point, one time 
step back. 
5. Results 
5.1. Ambient température and transmission through the bottom 
The ambient temperature varies between 30 and t^O C. The temperature in the 
container is -20 C. The minimum heatflow corresponds with a temperature difference 
of 50 K and the maximum heatflow with 60 k. The influence is 20% according to the 
lowest temperature difference. From table 1 to 2 it follows that the calculated 
difference is 19,5%.of walls not facing the sun. The reference container behaves 
better than the practical container. The difference between maximum and minimum 
heat flow through the bottom is only 13%. This can be explained by the thickness 
of the insulation and the corresponding time lag of 3 to 4 hours. 
5.2. Effect of radiation_on total^  transmission 
Without sunshine the mean total transmission of the reference container is 2841 W. 
The mean daily total transmission with sunshine is 3268 W. The effect of radiation 
is only 15%. The maximum heat flow is 4000 W, thus k\% more than the mean total 
transmission without radiation. 
5.3. iffeçt of orientation 
Studying table 5 it is clear that the effect of the orientation of the container 
is neglectable. 
Only the maximum heat flow of the practical container In the north-south 
orientation is much higher than in the north-west/south-east orientation; 
3999 - 3847 = 152 V. 
The difference of the reference container is only 61 W and reversed as well. 
5.4. Reference and practical container 
There is no real difference between the transmission of the reference and the 
practical container. 
-3-
Table 1. Heat flows in W through walls of a reference container. Orientation 
north-south 
time in 
hour 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
top 
609 
600 
591 
585 
588 
639 
729 
837 
951 
1065 
1185 
1281 
1329 
1338 
1305 
1218 
1110 
1005 
888 
798 
705 
' 648 
636 
624 
612 
east 
609 
600 
591 
585 
588 
783 
1008 
1104 
1110 
1059 
972 
867 
738 
684 
693 
702 
699 J 
693 j 
684 
672 
660 
648 
636 
624 
612 
west 
609 
6OO 
591 
585 
588 
594 
603 
615 
627 
639 
651 
660 
672 
75P 
900 
1038 
1131 
1182 
1167 
1011 
768 
648 
636 
624 
612 
bottom + 
north + south 
863 
850 
837 
829 
833 
842 
854 
871 
888 
905 
922 
935 
952 
969 
982 
990 
990 
982 
969 
952 
935 
918 
901 
884 
867 
total 
2689 
2650 
26IO 
2583 
2597 
2857 
3194 
3427 
3576 
3668 
3730 
3743 
3691 
3741 
3879 
3948 
3930 
3861 
3708 
3433 
3068 
2862 
2809 
2756 
2703 
. 2 t _ 
Table 2. Heat flows in W through walls of a reference container. Orientation 
north-west/south-east 
time in 
hour 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
top 
609 
600 
591 
585 
588 
639 
729 
837 
951 
1065 
1185 
1281 
1329 
1338 
1305 
1218 
1110 
1005 
888 
798 
705 
648 
636 
624 
612 
east 
side 
732 
725 
714 
706 
706 
917 
1170 
1261 
1218 
1112 
899 
797 
812 
826 
837 
844 
844 
837 
826 
812 
797 
782 
768 
754 
732 
west 
side 
732 
725 
714 
706 
710 
717 
728 
743 
757 
772 
786 
826 
942 
1069 
1174 
1246 
1268 
1207 
1098 
964 
840 
782 
761 
754 
732 
bottom 
609 
600 
590 
585 
587 
594 
602 
615 
627 
639 
650 
660 
672 
684 
692 
699 
699 
692 
684 
672 
660 
647 
635 
624 
612 
total 
2682 
2650 
2610 
2583 
2593 
2867 
3231 
3456 
3553 
3589 
3521 
3565 
3755 
3917 
4009 
4008 
3922 
3742 
3496 
3246 
3003 
2861 
2801 
2756 
2688 
-5-
Table 3. Heat flows (in W) through walls of practical container. Orientation 
north-south 
time in 
hours 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
IA 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
top 
186 
176 
168 
165 
158 
156 
156 
161 
173 
191 
210 
233 
263 
287 
302 
315 
315 
303 
293 
276 
255 
233 
213 
198 
186 
east 
IO38 
1025 
1010 
1005 
1007 
1470 
I8OO 
1916 
1893 
I79O 
1623 
1443 
1209 
1179 
1190 
1203 
1200 
II85 
1166 
1145 
1128 
1106 
1085 
1065 
1046 
west 
IO38 
1025 
1010 
1005 
1007 
1020 
1040 
1059 
1080 
1100 
1119 
1140 
1160 
1344 
1610 
1833 
1976 
2043 
1983 
1629 
1205 
1106 
1085 
IO65 
1046 
bottom 
165 
161 
158 
158 
156 
153 
153 
153 
153 
156 
156 
158 
161 
165 
168 
168 
171 
173 
173 
173 
173 
171 
171 
168 
165 
north + 
south 
253 
25O 
246 
243 
244 
247 
251 
256 
261 
266 
271 
275 
280 
285 
288 
291 
29I 
288 
285 
280 
275 
269 
265 
260 
255 
total 
2682 
2639 
2594 
2578 
2574 
3048 
3402 
3547 
3562 
3505 
3381 
3251 
3075 
3262 
3560 
3812 
3955 
3999 
3902 
3505 
3038 
2887 
2821 
2758 
27OO 
Table 4. Heat 'flows in W through walls of a practical container. Orientation 
north-west/south-east 
time in 
hour 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
top 
186 
176 
168 
165 
158 
156 
156 
161 
173 
191 
210 
233 
263 
287 
302 
315 
315 
303 
233 
276 
255 
233 
213 
198 
186 
north-
east 
1035 
1025 
1010 
1005 
1007 
1413 
1730 
179^ 
1704 
1533 
1190 
1140 
1158 
1179 
1194 
1203 
1196 
1185 
1166 
1145 
1128 
1106 
1089 
1068 
1046 
south-
west 
1035 
1025 
1010 
1005 
1007 
1020 
1040 
1059 
1080 
1100 
1119 
1194 
1391 
1556 
1704 
1790 
1800 
1680 
1515 
1316 
1155 
1106 
1085 
1068 
1046 
south-
east 
126 
125 
123 
121 
121 
158 
201 
217 
209 
191 
155 
137 
140 
142 
144 
145 
145 
144 
142 
140 
137 
134 
132 
130 
126 
north-
west 
126 
125 
123 
121 
122 
123 
125 
128 
130 
133 
135 
142 
162 
184 
202 
214 
218 
208 
. 189 
166 
145 
134 
131 
130 
126 
bottom 
165 
161 
158 
158 
156 
153 
153 
153 
153 
156 
156 
158 
161 
165 
168 
168 
171 
173 
173 
173 
173 
171 
171 
168 
165 
total 
2673 
2640 
2595 
2577 
2575 
3023 
3408 
3513 
3451 
3307 
2966 
3007 
3278 
3515 
3715 
3837 
3847 
3700 
3481 
3219 
2994 
2888 
2822 
2762 
2697 
Table 5. Maximum and minimum heat flows 
container 
type 
reference 
pract ical 
ori entat ion 
D 
^ 
D 
$ 
heat fl 
maximum 
3948 (15) 
4009 (14) 
3999 (17) 
3847 (16) 
ow in y 
minimum 
2583 (3) 
2583 (3) 
2574 (4) 
2575 (4) 
figures between ( ) give the time 
Table 6. Radiation on walls of a container under South-1 talian conditions, and 
ambient temperature 
t ime in 
hour 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
22 
23 
24 
ambi ent 
temp. C 
32 
31 
30,4 
30 
30,3 
31 
32 
33 
34 
35 
36 
37 
38 
39 
39,6 
40 
39,7 
39 
33 
37 
36 
35 
34 
33 
32 
/ 
top 
0 
0'" 
0 
0 
0 
100 
200 
340 
470 
600 
750 
830 
850 
830 
750 
600 
470 
340 
200 
130 
0 
0 
0 
0 
0 
radiation in W/m2 
east-
s ide 
0 
0 
0 
0 
0 
400 
600 
650 
600 
500 
350 
200 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
west-
s ide 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
150 
350 
500 
600 
650 
600 
300 
0 
0 
0 
0 
0 
north-
s ide 
0 
, 0 
0 
0 
0 
350 
550 
550 
450 
300 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
south-
s ide 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
50 
200 
300 
400 
450 
450 
350 
240 
100 
0 
0 
0 
0 
0 
Wageningen, 13 april 1982 
GvB/MJ 


van Beek, G.

NARCIS 

http://library.wur.nl/WebQuery/wurpubs/fulltext/335433

Heat transmission of a reference and practical container under subtropical conditions

Abstract

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Wageningen Yield

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