MIL-HDBK-1003/7

The condensing surface may be calculated by use of Equation 5.

7.2.9

Surface.

EQUATION:

A = Q/Um

(5)

where:

condensing surface (outside active tube area), ft2.

A

=

Q

=

condenser heat load = W x Hr, Btu/h

W

=

exhaust steam from turbine, lb/h

Hr

=

heat rejected latent heat of exhaust steam, 950 Btu/lb for

nonreheat unit, 980 Btu/lb for reheat unit

U = heat transfer coefficient = C x V0.5 x C1 x C2 x Cf

V = velocity of cooling water through tubes, fps

C x V0.5

= heat transfer coefficient at 70 deg F, (see Figure 30)

C1 = correction factor for inlet water temperatures other than

70 degrees F, (see Figure 30)

C2 = correction factor for tube material and thickness other

than No. 18 BWG Admiralty (see Figure 30)

Cf = correction factor for tube cleanliness, (see para. 7.2.8)

m = logarithmic mean temperature difference

=

(t2 - t1)/{loge[(ts - t1)/(ts - t2)]}

t2 = cooling water outlet temperature, degrees F

t1 = cooling water inlet temperature, degrees F

corresponding to condenser pressure

May be calculated by use of Equation 10.

7.2.10

Cooling Water Flow.

EQUATION:

G

=

Q/500(t2 - t1)

(10)

where:

G

=

Condenser cooling water flow, gpm

Condenser Materials. Typical materials of construction for condenser shell,

7.3

water boxes, tube sheets, and tubes are listed in HEIS. Recommended tube, tube sheet,

and water box materials are shown in Table 16.

Shell. The condenser shell is usually welded steel construction reinforced

7.3.1

against collapsing forces resulting from high vacuum. Carbon steels ASTM A283 Grade C,

Specification for Low and Intermediate Tensile Strength Carbon Steel Plates, Shapes,

Shapes, and Bars, ASTM A285 Grade C, Specification for Pressure Vessel Plates, Carbon

Steel, Low and Intermediate Tensile Strength, and ASTM A516 Grade 70, Specification for

102

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