loRCED-COOLED TRANSFOBMER8 171 



It is tlni- . \i. It-lit that eaeh case must 1 6 M-pai-ately considered. 

 ( Mie -j;ill"!i i> .|ii,il t . l.":i() ru cm, and tin- volume of water per 

 second may in the la>t rase be expressed as 



1.17 x 1580 



-GOT =88cucm. 



If we adopt (),." i; : second for the speed of flow of the 



ss 



r, then the area of the pipe must be r7 r = 1,76 sq cm and 



*)() 



tin- internal diameter must be 1.") nun. The thickness of the 



IS tubing will usually he about 1,'25 mm. Consequently 



the external diameter is 17,5 mm and the external surface p< v 



meter length of tubing is (10 X 0,175 X T; =) 5,5 sq dm. 



Tin- rate ot transference of heat from one medium to another 



i> ;i matter which has not yet been reduced to a reliable basis 



and is still usually determined by experiments. It d-p. 



upon the speed of flow of the water and on other vimalde>. 



us take it at 1,5 watt per degree per sq dm of heating 



ice. In our case we are dealing with 14 000 watts. The 



mean difference of temperature between the oil and the \ 



60 _ 53 + 15 = 26. 



A 



Consequently tlie water will take up the h at at the rate of 

 X 1,5 ) 89 watts p.-r Bq dm. and \\ . -hall require to 



provide / ] l . ; n ) nn =\ 860 sq dm ox total length of =) 



;i; metei a of tubing. 



In a pape: L. f-iv the Sell. i; , tady section of the 



American Institute of Electri<-al I'.i 



the arrangement illu.st rat. (1 in 1 ig. 100, in \\hi-h a tian-t.rmer 

 lindrical harrier in:- the 



and the external c\ lindrical sides of the 



|iute down to the bottom ^i the 

 case. Tin- oil Hidings 



