Page 256 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

HEAT TRANSFER, INSULATION, AND FREEZE PROTECTION

5.40 CHAPTER FIVE

FIGURE 5.14 Volumetric latent heat of fusion.

To illustrate the use of the modified Berrigan formula, the following example will deter-
mine the frost depth for a project in Green Bay, Wisconsin, with the following conditions:
Mean annual temperature 43.7°F (from NOAA)
Length of freezing season 200 days (obtained from Fig. 5.10)
Soil properties Sandy soil, snow cover
Weight 100 lb/ft 3
Moisture content 15%
3
Latent heat of fusion 2160 Btu/ft (obtained from Fig. 5.14)
2
Thermal conductivity 1.01 Btu/h/ft /°F (obtained from Fig. 5.13)
Surface freezing index N 3 AF = 2150 degree days. (AF is obtained from Fig. 5.9,
coldest reading; N is obtained from Table 5.12, snow cover;
therefore, 2150 × 1.0 = 2150 surface freezing index.)
To obtain the coefficient C refer to Fig. 5.15. Enter with the fusion parameter and ther-
mal ratio. To find the fusion parameter [FP in Eq. (5.15)], first calculate AD:

AD = 2150 = 10 7.
200
Therefore, FP = 10 7 . × 28 2 . = 10 7 0 013 0 14. × . = .
2160

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