??? 利用 電伴熱產(chǎn)品所產(chǎn)生的熱量來(lái)補(bǔ)償需伴熱的管道等工藝裝置所散耗的熱量，以維持其相應(yīng)的介質(zhì)溫度來(lái)滿足工藝要求。所以正確計(jì)算出管道等工藝裝置的熱耗散量，對(duì)伴熱所需的介質(zhì)溫度是至關(guān)重要的。為此在計(jì)算熱耗散量前，必須先找出有關(guān)的幾個(gè)重要參數(shù)：如TA（管道等介質(zhì)維持溫度）。TB（當(dāng)?shù)刈畹铜h(huán)境溫度）、d（管道的外徑）、do（管道內(nèi)徑）、δ（保溫層厚度）。另外還需知道保溫材料的名稱和敷設(shè)環(huán)境（室內(nèi)或室外、地面或埋地）。當(dāng)知道了這些參數(shù)，再借助于有關(guān)的計(jì)算方式和表就能進(jìn)行具體計(jì)算，從而得到所需的散熱量。 管道及附件耗散熱量的計(jì)算
確定管道的熱耗散量
??? 首先應(yīng)知道管道的口徑、保溫層材料及厚度和所需維持溫度之差△T，查管道散熱量表，（乘以適當(dāng)?shù)谋叵禂?shù)），就能得到單位長(zhǎng)管道的散熱量，如果管子在室內(nèi)則再乘以0.9。如果伴熱的是塑料管道，因?yàn)樗芰系膶?dǎo)熱性遠(yuǎn)低于碳鋼（0.12:25），故可用0.6-0.7的系數(shù)對(duì)正常散熱量加以修正。
例1：某廠有一管線，管徑為1/2"，保溫材料是硅酸鈣，厚度10mm，管道中流體為水，水溫需保持10℃，冬季最低氣溫是-25℃，環(huán)境無(wú)腐蝕性，周圍供電條件380V、220V均有，求管道每米熱損失？
??? 步驟一：△T = TA - TB =10℃-（-25℃）=35℃
??? 步驟二：查管道散熱量表，管徑1/2"。10mm保溫層。
??????????? 當(dāng)△T =30℃熱損失為11.0w/m，當(dāng)△T =40℃熱損失為14.9w/m，△T =35℃時(shí)，每米損失可采用中間插入法求得（因表中無(wú)QB值）。
????????? ???QB=11.0w/m+（14.9w/m - 11.0w/m）[（35-30）÷（40-30）]=12.95w/m
??? 步驟三：保溫層采用硅酸鈣，查保溫材料修正數(shù)表乘以保溫系數(shù)f及綜合系數(shù)1.4
??????????? Qr=1.4QB×f=1.4×12.95w/m×1.50=27.195w
??? 答案：管道每米損失熱量27.195W
保溫材料修正數(shù)表
|
保溫材料 |
保溫系數(shù)F |
導(dǎo)熱常熟（w/m.k）10℃ |
|
玻璃纖維 |
1.0 |
0.036 |
|
巖棉（管殼） |
1.22 |
0.044 |
|
棉管殼 |
1.11 |
0.04 |
|
珍珠巖 |
1.31 |
0.047 |
|
聚氨酯泡沫塑料 |
0.67 |
0.024 |
|
聚苯乙烯泡沫塑料 |
1.86 |
0.031 |
|
硅酸鈣 |
1.50 |
0.054 |
|
石棉繩 |
1.83 |
0.066 |
|
復(fù)合硅酸鹽氈FHP-VB |
0.65 |
0.0234 |
|
硅酸鋁耐火纖維板 |
1.0 |
0.036 |
?
確定管道閥體的散熱量
??? 閘閥散熱量通常是相聯(lián)口徑管道每米熱損失的1.22倍；如果是球閥，則可用0.7乘以閘閥熱耗量，如果蝶型閥（節(jié)流閥），則乘以0.5；如果是浮式球閥，則乘以0.6。
??? 從產(chǎn)品規(guī)格中可知電伴熱帶的工作電壓，功率值。如算出單位長(zhǎng)度熱損失大于電伴熱帶單位長(zhǎng)度的發(fā)熱額定值，則可用以下方法來(lái)彌補(bǔ)：
??? ● 采用卷繞法（如果用此法，則要先求出熱損失對(duì)電伴熱帶發(fā)熱功率的比值。如在2"管道上熱損失是24w/m，而電伴熱帶功率20w/m，則比值=24/20是1.2倍，查電伴熱帶跨距表可知2"管道上間距為280mm的這種繞法能滿足管道的熱耗散。）
??? 除上面的兩種方法外，還可采取增加保溫層厚度或采取導(dǎo)熱系數(shù)較低的保溫材料等附加措施彌補(bǔ)。
電伴熱帶跨距表（單位：mm）
|
管徑 |
每米管子所需電伴熱帶數(shù)（比值） |
|
1.1 |
1.2 |
1.3 |
1.4 |
1.5 |
|
1″ |
229 |
152 |
102 |
102 |
76 |
|
5/4″ |
305 |
203 |
152 |
127 |
102 |
|
3/2″ |
330 |
229 |
178 |
152 |
127 |
|
2″ |
432 |
280 |
229 |
203 |
178 |
|
5/2″ |
508 |
356 |
280 |
229 |
203 |
|
3″ |
610 |
432 |
330 |
280 |
254 |
|
13/4″ |
711 |
483 |
381 |
330 |
280 |
|
4″ |
787 |
533 |
432 |
356 |
305 |
|
9/2″ |
889 |
610 |
483 |
406 |
356 |
|
5″ |
990 |
660 |
533 |
457 |
381 |
|
6″ |
1168 |
787 |
635 |
533 |
457 |
|
8″ |
1500 |
1041 |
838 |
711 |
610 |
?
??? 電伴熱帶跨距表中保溫材料是采用玻璃纖維為標(biāo)準(zhǔn)的，如用其字材料可參見(jiàn)保溫材料修正表的系數(shù)進(jìn)行修正，如前面例1所述。 為完善整個(gè)加熱系統(tǒng)，還須考慮法蘭，彎頭及管道金屬托架散熱損失所需的電伴熱帶長(zhǎng)度及預(yù)留供電電源接線用的長(zhǎng)度，同時(shí)還要考慮預(yù)留供中間接線盒接線長(zhǎng)度。法蘭一般加上2倍的管徑長(zhǎng)度，彎頭加上1.5倍的管徑長(zhǎng)度；管道金屬托架加上3-5倍的管徑長(zhǎng)度，預(yù)留電源接線長(zhǎng)度一般為1米，中間接線盒預(yù)留約0.5米。當(dāng)計(jì)算出有關(guān)管道各附件的長(zhǎng)度后，再加伴熱管所需的電伴熱帶長(zhǎng)度，我們就能得到整個(gè)系統(tǒng)所需電伴熱帶的總長(zhǎng)度。
?
管道散熱量表
|
保溫厚度
mm |
溫差℃
△T |
管道大小 |
15 |
20 |
25 |
32 |
40 |
50 |
65 |
|
內(nèi)徑mm |
1/2 |
3/4 |
1 |
5/4 |
3/2 |
2 |
5/2 |
|
英制(時(shí))1/4
外徑mm14 |
21 |
27 |
34 |
42 |
48 |
60 |
76 |
|
? |
20 |
6.2 |
7.2 |
8.5 |
10.1 |
12.1 |
13.6 |
16.4 |
19.3 |
|
30 |
9.4 |
11.0 |
12.9 |
15.4 |
18.5 |
20.4 |
24.9 |
29.4 |
|
40 |
12.7 |
14.9 |
17.5 |
20.8 |
25.0 |
27.9 |
33.7 |
39.7 |
|
20 |
20 |
4.0 |
4.6 |
5.3 |
6.2 |
7.3 |
8.0 |
9.5 |
11.1 |
|
30 |
6.2 |
7.0 |
8.1 |
9.4 |
11.1 |
12.2 |
14.5 |
16.8 |
|
40 |
8.3 |
9.5 |
10.9 |
12.7 |
15.0 |
16.5 |
19.6 |
22.8 |
|
60 |
12.8 |
14.7 |
16.9 |
19.6 |
23.1 |
25.5 |
30.2 |
35.1 |
|
25 |
20 |
3.6 |
4.1 |
4.6 |
5.3 |
6.2 |
6.9 |
8.1 |
9.3 |
|
30 |
5.4 |
6.2 |
7.1 |
8.1 |
9.5 |
10.4 |
12.3 |
14.2 |
|
40 |
7.4 |
8.4 |
9.5 |
11.0 |
12.9 |
14.1 |
16.6 |
19.2 |
|
60 |
11.4 |
12.9 |
14.7 |
17.0 |
19.8 |
21.8 |
25.6 |
29.6 |
|
80 |
15.6 |
17.7 |
20.2 |
23.3 |
27.2 |
29.9 |
35.1 |
40.6 |
|
100 |
20.1 |
22.8 |
26.1 |
30.1 |
35.1 |
38.6 |
45.4 |
52.5 |
|
30 |
20 |
3.3 |
3.7 |
4.2 |
4.8 |
5.5 |
6.1 |
7.1 |
8.1 |
|
30 |
5.0 |
5.6 |
6.3 |
7.3 |
8.4 |
9.2 |
10.8 |
12.4 |
|
40 |
6.7 |
7.6 |
8.6 |
9.8 |
11.4 |
12.5 |
14.6 |
16.8 |
|
60 |
10.3 |
11.7 |
13.2 |
15.1 |
17.6 |
19.2 |
22.5 |
25.9 |
|
80 |
14.2 |
16.0 |
18.2 |
20.8 |
24.1 |
26.4 |
30.9 |
35.5 |
|
100 |
18.3 |
20.7 |
23.4 |
26.8 |
31.1 |
34.1 |
39.8 |
45.8 |
|
120 |
22.7 |
25.6 |
29.0 |
33.2 |
38.6 |
42.2 |
49.3 |
56.7 |
|
140 |
27.2 |
30.8 |
34.9 |
40.0 |
46.4 |
50.8 |
59.4 |
68.3 |
|
160 |
32.1 |
36.2 |
41.1 |
47.1 |
54.6 |
59.8 |
69.9 |
80.4 |
|
180 |
37.1 |
42.0 |
47.6 |
54.5 |
63.2 |
69.2 |
80.9 |
93.0 |
|
40 |
20 |
2.8 |
3.2 |
3.6 |
4.0 |
4.6 |
5.0 |
5.8 |
6.6 |
|
30 |
4.3 |
4.8 |
5.4 |
6.1 |
7.0 |
7.7 |
8.9 |
10.4 |
|
40 |
5.8 |
6.5 |
7.3 |
8.3 |
9.5 |
10.4 |
12.0 |
13.7 |
|
60 |
9.0 |
10.1 |
11.3 |
12.8 |
14.7 |
16.0 |
18.5 |
21.1 |
|
80 |
12.3 |
13.8 |
15.5 |
17.6 |
20.2 |
21.9 |
25.4 |
28.9 |
|
100 |
15.9 |
17.8 |
20.2 |
22.7 |
26.0 |
28.3 |
32.8 |
37.3 |
|
120 |
19.7 |
22.1 |
24.8 |
28.1 |
32.2 |
35.1 |
40.6 |
46.2 |
|
140 |
23.7 |
26.5 |
29.8 |
33.8 |
38.8 |
42.2 |
48.8 |
55.6 |
|
160 |
27.9 |
31.2 |
35.1 |
39.8 |
45.6 |
49.7 |
57.4 |
65.5 |
|
180 |
32.3 |
36.2 |
40.6 |
46 |
52.9 |
57.5 |
66.5 |
75.8 |
|
50 |
20 |
2.6 |
2.8 |
3.2 |
3.6 |
4.1 |
4.2 |
5.0 |
5.7 |
|
30 |
3.9 |
4.3 |
4.8 |
5.4 |
6.2 |
6.7 |
7.7 |
8.7 |
|
40 |
5.3 |
5.9 |
6.5 |
7.3 |
8.4 |
9.1 |
10.4 |
11.8 |
|
60 |
8.1 |
9.0 |
10.1 |
11.3 |
12.9 |
14.0 |
16.0 |
18.1 |
|
80 |
11.2 |
12.4 |
13.8 |
15.5 |
17.7 |
19.1 |
22.0 |
24.9 |
|
100 |
14.4 |
16.0 |
17.8 |
20.1 |
22.8 |
24.7 |
28.4 |
32.1 |
|
120 |
17.8 |
19.8 |
22.1 |
24.8 |
28.3 |
30.6 |
35.1 |
39.8 |
|
140 |
21.5 |
23.8 |
26.6 |
29.9 |
34.0 |
36.8 |
42.3 |
47.9 |
|
160 |
25.3 |
28.1 |
31.3 |
35.2 |
40.1 |
43.4 |
49.8 |
56.3 |
|
180 |
29.2 |
32.5 |
36.2 |
40.7 |
46.4 |
50.2 |
57.6 |
65.2 |
|
80 |
20 |
2.1 |
2.3 |
2.6 |
2.8 |
3.2 |
3.4 |
3.8 |
4.3 |
|
30 |
3.2 |
3.5 |
3.9 |
4.3 |
4.8 |
5.2 |
5.8 |
6.5 |
|
40 |
4.4 |
4.8 |
5.2 |
5.8 |
6.5 |
7.0 |
7.9 |
8.8 |
|
60 |
6.7 |
7.4 |
8.1 |
9.0 |
10.1 |
10.8 |
12.1 |
13.5 |
|
80 |
9.2 |
10.1 |
11.1 |
12.3 |
13.8 |
14.8 |
16.6 |
18.6 |
|
100 |
11.9 |
13.2 |
14.3 |
15.9 |
17.8 |
19.1 |
21.5 |
24.0 |
|
120 |
14.7 |
16.1 |
17.8 |
19.7 |
22.0 |
23.6 |
26.6 |
29.7 |
|
140 |
17.7 |
19.4 |
21.4 |
23.6 |
26.5 |
28 |
32.0 |
35.7 |
|
160 |
20.9 |
22.9 |
25.1 |
27.8 |
31.2 |
33.4 |
37.7 |
42.1 |
|
180 |
24.1 |
26.5 |
29.1 |
32.2 |
36.1 |
38.7 |
43.7 |
48.7 |
|
80 |
100 |
150 |
200 |
250 |
300 |
350 |
400 |
450 |
500 |
600 |
|
3 |
4 |
6 |
8 |
10 |
12 |
14 |
16 |
18 |
20 |
24 |
|
89 |
114 |
168 |
219 |
273 |
324 |
374 |
426 |
476 |
530 |
630 |
|
23.0 |
28.8 |
41.1 |
52.6 |
64.7 |
76.1 |
83.3 |
94.6 |
105.9 |
117.2 |
139.7 |
|
35.0 |
43.8 |
62.5 |
80.8 |
98.5 |
115.8 |
26.7 |
143.9 |
161.1 |
178.3 |
212.6 |
|
47.3 |
59.2 |
54.5 |
108.2 |
133.2 |
156.6 |
171.3 |
194.6 |
161.1 |
178.3 |
212.6 |
|
13.0 |
16.0 |
22.5 |
28.5 |
34.9 |
40.9 |
44.7 |
50.7 |
56.7 |
62.6 |
74.6 |
|
19.8 |
24.4 |
24.3 |
43.4 |
52.5 |
62.3 |
68.0 |
77.1 |
86.2 |
95.3 |
113.4 |
|
26.7 |
33.0 |
46.3 |
58.7 |
71.9 |
84.2 |
92.0 |
104.3 |
116.6 |
128.9 |
153.4 |
|
41.2 |
50.9 |
71.4 |
90.5 |
110.8 |
129.9 |
141.8 |
160.8 |
179.7 |
198.7 |
236.5 |
|
10.9 |
13.4 |
18.6 |
23.5 |
28.7 |
33.5 |
36.5 |
41.4 |
46.2 |
51.1 |
60.7 |
|
16.6 |
20.3 |
28.3 |
35.7 |
43.6 |
51.0 |
55.6 |
63.0 |
70.3 |
77.7 |
92.4 |
|
22.4 |
27.5 |
38.2 |
48.3 |
59.0 |
69.0 |
75.2 |
85.2 |
95.1 |
105.1 |
124.9 |
|
34.5 |
42.4 |
59.0 |
74.5 |
90.9 |
106.3 |
115.9 |
131.3 |
146.7 |
162.0 |
192.6 |
|
47.4 |
58.2 |
81.0 |
102.3 |
124.8 |
146.0 |
159.2 |
180.3 |
201.4 |
222.4 |
246.5 |
|
61.2 |
75.2 |
104.5 |
132.0 |
161.1 |
188.5 |
205.5 |
232.8 |
260.0 |
287.1 |
341.5 |
|
9.50 |
11.6 |
15.9 |
20.1 |
24.4 |
28.5 |
31.0 |
35.1 |
39.2 |
43.2 |
51.3 |
|
14.4 |
17.6 |
24.3 |
30.5 |
37.1 |
43.3 |
47.2 |
53.4 |
59.6 |
65.8 |
78.1 |
|
19.5 |
23.8 |
32.8 |
41.3 |
50.2 |
58.6 |
63.8 |
72.2 |
80.6 |
88.9 |
105.6 |
|
30.3 |
36.6 |
50.6 |
63.6 |
77.4 |
90.4 |
98.4 |
111.4 |
124.3 |
137.1 |
162.9 |
|
41.2 |
50.3 |
69.4 |
87.3 |
106.3 |
124.0 |
135.1 |
152.9 |
170.6 |
188.3 |
223.6 |
|
53.2 |
65.0 |
89.7 |
112.8 |
1377.2 |
160.2 |
174.5 |
179.4 |
220.3 |
243.1 |
288.7 |
|
65.9 |
80.4 |
111.0 |
139.6 |
169.9 |
198.3 |
216.1 |
244.4 |
272.8 |
301.1 |
357.5 |
|
79.3 |
96.8 |
133.5 |
168.0 |
204.4 |
238.6 |
259.9 |
294.0 |
328.1 |
262.1 |
430.1 |
|
93.3 |
113.9 |
157.2 |
197.7 |
240.6 |
280.8 |
306.0 |
346.1 |
386.2 |
426.3 |
506.2 |
|
108.1 |
131.9 |
182.0 |
228.9 |
278.6 |
325.2 |
354.2 |
400.7 |
447.1 |
493.5 |
586.2 |
|
7.6 |
9.2 |
12.6 |
25.7 |
19.0 |
22.1 |
24.0 |
27.4 |
30.2 |
33.3 |
39.4 |
|
11.6 |
14.1 |
19.1 |
23.9 |
28.9 |
33.6 |
36.6 |
41.3 |
45.9 |
50.6 |
60.6 |
|
15.7 |
19.0 |
25.9 |
32.3 |
39.1 |
45.5 |
49.4 |
55.8 |
62.1 |
68.5 |
81.1 |
|
24.3 |
29.3 |
39.9 |
49.8 |
60.3 |
70.1 |
76.2 |
86.0 |
95.8 |
105.6 |
125.1 |
|
33.3 |
40.2 |
54.8 |
68.4 |
82.7 |
96.2 |
104.6 |
118.0 |
131.5 |
144.9 |
717.7 |
|
43.0 |
52.0 |
70.8 |
88.3 |
106.8 |
124.2 |
135.1 |
152.4 |
169.8 |
187.1 |
221.7 |
|
53.3 |
64.4 |
87.6 |
109.3 |
132.3 |
153.9 |
167.3 |
188.8 |
210.3 |
231.7 |
274.5 |
|
64.1 |
77.4 |
105.4 |
131.5 |
259.1 |
185.1 |
201.2 |
227.1 |
252.9 |
278.7 |
330.2 |
|
75.4 |
91.1 |
124.1 |
154.8 |
187.3 |
217.9 |
236.9 |
267.3 |
297.7 |
328.1 |
388.7 |
|
87.3 |
105.5 |
143.7 |
179.3 |
216.9 |
252.2 |
274.3 |
309.5 |
344.7 |
379.9 |
450.1 |
|
6.5 |
7.8 |
10.5 |
13.1 |
15.7 |
18.2 |
19.8 |
22.3 |
24.7 |
27.2 |
32.2 |
|
9.9 |
11.9 |
16.0 |
19.9 |
23.9 |
27.7 |
30.1 |
33.9 |
37.6 |
41.4 |
48.8 |
|
13.4 |
16.1 |
21.7 |
26.9 |
32.3 |
37.5 |
40.7 |
45.8 |
50.9 |
56.0 |
66.2 |
|
20.7 |
24.8 |
33.4 |
41.4 |
49.9 |
57.8 |
62.7 |
70.6 |
78.5 |
86.3 |
102.1 |
|
28.5 |
34.1 |
45.9 |
56.8 |
68.4 |
79.3 |
86.1 |
96.9 |
107.7 |
118.5 |
140.1 |
|
36.7 |
44.0 |
59.2 |
73.4 |
88.3 |
102.4 |
111.1 |
125.1 |
139.1 |
153.0 |
180.9 |
|
45.5 |
54.4 |
73.3 |
90.9 |
109.4 |
126.8 |
137.6 |
154.9 |
72.2 |
189.5 |
224.0 |
|
64.4 |
77.2 |
103.9 |
128.7 |
154.9 |
179.5 |
194.9 |
219.4 |
243.9 |
268.3 |
317.2 |
|
45.5 |
54.4 |
73.3 |
90.9 |
109.4 |
126.8 |
137.6 |
154.9 |
72.2 |
189.5 |
224.0 |
|
54.7 |
65.6 |
88.2 |
109.3 |
131.6 |
152.2 |
165.5 |
186.4 |
207.2 |
227.9 |
269.4 |
|
64.4 |
77.2 |
103.9 |
128.7 |
154.9 |
179.5 |
194.9 |
219.4 |
243.9 |
268.3 |
317.2 |
|
74.6 |
89.4 |
120.3 |
149.0 |
179.4 |
207.9 |
225.6 |
254.0 |
282.4 |
310.7 |
367.2 |
|
4.8 |
5.7 |
7.4 |
9.0 |
10.7 |
12.3 |
13.3 |
14.9 |
16.4 |
18.0 |
21.1 |
|
7.3 |
8.6 |
11.3 |
13.7 |
16.3 |
18.7 |
20.2 |
22.6 |
25.0 |
27.4 |
32.1 |
|
9.9 |
11.6 |
15.2 |
18.5 |
22.0 |
25.3 |
27.3 |
30.6 |
33.8 |
37.0 |
43.5 |
|
15.3 |
17.9 |
23.5 |
28.6 |
34.0 |
39.0 |
42.1 |
47.1 |
52.1 |
57.1 |
67.0 |
|
20.9 |
24.6 |
32.2 |
39.2 |
46.6 |
53.5 |
54.8 |
64.7 |
71.5 |
78.3 |
92.0 |
|
27.0 |
31.8 |
41.6 |
50.6 |
60.2 |
69.1 |
74.6 |
83.5 |
92.3 |
101.2 |
118.8 |
|
33.5 |
39.3 |
51.1 |
62.7 |
74.5 |
85.5 |
92.4 |
103.4 |
114.3 |
125.3 |
147.1 |
|
40.3 |
47.3 |
62.9 |
75.4 |
89.6 |
102.9 |
11.2 |
124.4 |
137.5 |
150.7 |
176.9 |
|
47.4 |
55.7 |
72.9 |
88.8 |
105.5 |
121.1 |
130.9 |
146.4 |
161.9 |
177.4 |
208.3 |
|
54.9 |
64.5 |
84.4 |
102.8 |
122.2 |
140.3 |
151.5 |
169.5 |
187.5 |
205.4 |
241.2 | | 
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