3-7.Three types of drying 2.Drying of the surface attached water

Even if it tells “dryness” to a mouthful, there are three kinds of dry work.

They are dryness of surface water of adhesion, dryness of the coating film, and internal dryness of material.
Since the preceding sections has explained the internal dryness, this section explains the surface dryness.

The drying time of surface adhesion water is determined by supply of evaporative latent heat.

Three types of drying 2.Drying of the surface attached water

The saturated vapor pressure of water and latent heat of evaporation

Temp.Pressurelatent heat
mmHgkcal/kgkJ/g
04.6597.12.502
14.9596.62.500
25.3596.02.498
35.7595.42.495
46.1594.92.493
56.5594.32.491
67.0593.82.488
77.5593.22.486
88.0592.62.483
98.6592.12.481
109.2591.52.478
119.8590.92.475
1210.5590.42.473
1311.2589.82.471
1412.0589.32.469
1512.8588.72.466
1613.6588.12.464
1714.5587.52.461
1815.5587.02.459
1916.5586.42.456
2017.5585.92.454
2118.6585.32.452
2219.8584.82.450
2321.1584.22.447
2422.4583.62.445
2523.8583.12.443
2625.2582.52.440
2726.7581.92.438
2828.3581.42.436
2930.0580.82.433
3031.8580.22.431
3133.7579.72.428
3235.7579.12.426
3337.7578.52.423
3439.9578.02.421
3542.2577.42.419
3644.6576.82.416
3747.1576.22.414
3849.7575.72.412
3952.4575.12.409
4055.3574.52.407
4158.3574.02.405
4261.5573.42.402
4364.8572.82.400
4468.3572.22.397
4571.9571.72.395
4675.7571.12.392
4779.6570.52.390
4883.7570.02.388
4988.0569.42.385
5092.5568.82.383
5197.2568.22.380
52102.1567.62.378
53107.2567.12.376
54112.5566.52.373
55118.1565.92.371
56123.9565.32.368
57129.9564.72.366
58136.1564.12.363
59142.7563.62.361
60149.4563.02.359
61156.5562.42.356
62163.8561.82.354
63171.5561.22.351
64179.4560.62.349
65187.6560.02.346
66196.2559.52.344
67205.0558.92.341
68214.3558.32.339
69223.8557.72.336
70233.8557.12.334
71244.1556.52.331
72254.7555.92.329
73265.8555.32.326
74277.3554.72.324
75289.2554.12.321
76301.5553.52.319
77314.2552.92.316
78327.4552.32.314
79341.1551.72.311
80355.3551.12.309
81369.9550.52.306
82385.0549.92.304
83400.7549.32.301
84416.9548.72.299
85433.6548.12.296
86450.9547.52.294
87468.7546.92.291
88487.2546.22.288
89506.2545.62.286
90525.9545.02.283
91546.2544.42.281
92567.1543.82.278
93588.7543.22.276
94611.0542.62.273
95634.0541.92.270
96657.7541.42.268
97682.1540.72.265
98707.3540.12.263
99733.3539.42.260
100760.0538.82.257
101787.0538.12.254
102815.2537.42.251
103844.2536.82.249
104874.5536.22.246
105906.1535.62.244
106938.4535.02.241
107971.6534.32.239
1081003.7533.72.236
1091040.0533.02.233
1101074.6532.42.231

The quantity of heat which heated material becomes a constant drying period, while waterdrop is on the surface, since it is consumed as vapor-ized latent heat.

Although it can heated to the temperature which can untill withstand the material, as shown in the following table, there is only a difference of 10% to 100 ℃ from 0 ℃.

It seems that there is little necessity of raising material temperature by force.

<<Evaporation heat of the water 1g >>

Temp.℃0℃20℃40℃60℃80℃100℃
latent heat2502J2454J2407J2359J2309J2257J

The adhering water has been adhered by the interfacial tension on the material surface.

The vapor pressure of water adhering is equal to the saturated vapor pressure, and since the evaporation temperature of water is proportional to pressure, if low pressure and a vacuum are used, low-temperature drying will be made.

Guide to the optimal wind drying heater

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