ENGINEERING EVALUATION 



347 



The heat loss is 



Q = 0.840 X 34 X 40 



Qp = 1,140 Btu/hr. 



Concrete Deck 



Since radiant heating cables were imbedded in the concrete deck, two inches below the 

 surface, it is logical to assume that this portion of the concrete would be maintained at a higher 

 temperature than the Sealab atmosphere. There a t^ of 95° F was selected for use in this cal- 

 culation. Film coefficients are neglected. 



Qd = K^ X Ae X At = 0.64 x 376 x 46 

 Qd = 11,100 Btu/hr. 



Uninsulated Hull Areas (Steel) 

 Film coefficient, hj 



A^ = 376 ft-^ 



Kj = 0.64 Btu/hr -ft-°F 

 t. = 48°F 



tad = 94°F 



Xd = 1 ft (avg) 



— (t-tj = h3(t3-t) 



25 X 12 



(t - 48) = h^ (88 - t) 



400 (t - 48) = h (88 - t) 

 h, = (88 - t)°" 

 Then if 



t = 48.25° 

 h^ = (88 - 48.25°)°" = 2.5 

 and substituting for t and h^ 



4(48.25 - 48) = 2.5(88 - 48.25) 

 100 = 99.4. 

 Therefore 

 h, = 2.5 



A, = 376 ft 2 



k3 = 25 Btu/hr-ft-°F 



K = 48°F 



ta = 88°F 



X , = 1 in. 



U. 



J_ ^ _J_ J^ 0.44 + 0.0025 

 h "^ k 2.5 "^ 400 



s s 



U, = 2.49 Btu/hr-ft2-°F 



