The remainder of this report describes the design methods, the final 

 design selected, the results of controlled tests in a large tank of seawater 

 at CEL, and the results of a 30-day immersion in Port Hueneme Harbor. 



DESIGN AND OPTIMIZATION OF THE HEAT TRANSFER MODULES 



Previous criteria provided by the sponser, required that some 28 kw 

 of heat be rejected in 12 vertical modules of the overall dimensions 

 shown in Figure 1. All of the useful heat to be converted in part to 

 electricity must be transferred radially from a high temperature heat 

 pipe in an area as shown. To provide for compression strength in the 

 longitudinal direction, at least 3/16 inch of most copper alloys would 

 be required, not crediting the additional strength and rigidity provided 

 by any fins used in the final design. A thimble thickness of 1/4 inch 

 was arbitrarily selected to utilize readily available materials. Based 

 on a design overpressure of 10,000 psi (approximately equivalent to 

 a 20,000-foot immersion depth in seawater), the resulting longitudinal 

 compressive stress in the 1/4-inch-thick thimble is: 



s = *( p2/4 > P = ^ P = 16,500 psi* (1) 

 c tt(D 2 - d 2 )/4 D 2 - d 2 



for the dimensions shown in Figures 2 and 3, or about l/6th the probable 

 compressive strength for structural copper; stronger alloys would provide 

 an even greater margin, as would any heavy fi-,s--an almost certain 

 eventuality in this type of convector. The heavy section is desirable to 

 produce even temperatures at the minor dianeter, d, and a long life in 

 the presence of corrosion. 



Seawater is an excellent cooling cedium; however, for the relatively 

 high unit area heat loading of 2,600 watts on a 0. 308-square-foot base 

 area, 



= (2600X3.4) = Q Btu/fo,.)/^) 



v/ 0.308 



an extended surface consisting of a number of vertical, heavy fins will 

 almost certainly be needed to produce a low base temperature. 



As a first trial, the following calculation was made of the temper- 

 ature drop through 70-30 copper-nickel: 



* See List of Symbols after Appendix B. 



