An investigation of wet-and dry-bulb psychrometry in metallic vapor-gas systems
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WETand d r y - b u l b p s y c h r o m e t r y is a technique for d e t e r m i n i n g vapor c o n c e n t r a t i o n in n o n c o n d e n s a b l e g a s e s f r o m m e a s u r e m e n t s of the s t e a d y - s t a t e t e m p e r a t u r e s of the gas and that of a bulb which is wetted by the liquid phase whose v a p o r c o n c e n t r a t i o n is being measured. T h i s technique has b e e n widely used in the study of s i m u l t a n e o u s heat and m a s s t r a n s f e r involving aqueous and o r g a n i c liquids but, as far as is known, it has n e v e r b e e n a t t e m p t e d with liquid m e t a l s . The p u r p o s e of this p a p e r is t h e r e f o r e to r e p o r t what may be the f i r s t study of w e t - and d r y - b u l b p s y c h r o m e t r y in liquid m e t a l s y s t e m s and to indicate its p o s s i b l e a p p l i c a t i o n s in the field of e x t r a c t i v e m e t a l lurgy. T H E O R E T I C A L CONSIDERATIONS M e t a l l i c v a p o r - g a s s y s t e m s a r e s i m i l a r to those involving aqueous or o r g a n i c liquids in that the g a s e o u s phase in each is a m i x t u r e of c o n d e n s a b l e and n o n c o n d e n s a b l e s p e c i e s . D i f f e r e n c e s e x i s t only in so f a r as they r e l a t e to the d i f f e r e n c e s in p h y s i c a l p r o p e r t y v a l u e s and the high t e m p e r a t u r e s r e q u i r e d for m e t a l s to attain s i g n i f i c a n t v a p o r p r e s s u r e . The r e l a t i o n s h i p between the v a p o r c o n c e n t r a t i o n in the gas, t e r m e d humidity, and the w e t - and d r y - b u l b t e m p e r a t u r e s can be r e a d i l y d e r i v e d f r o m the b a l a n c e between heat and m a s s t r a n s f e r . If the a r e a s a v a i l a b l e for heat and m a s s t r a n s f e r a r e equal the r e s u l t i n g equation for s t e a d y - s t a t e conditions is:
Hw-Hg
= (hg+ h r) ( T g - T w ) legMgPX
[1]
By i n s p e c t i o n , Eq. [1] c o n t a i n s hr as i n d e p e n d e n t v a r i a b l e which in t h e o r y is c a l c u l a b l e provided that the a s s u m p t i o n could be made that the two modes of heat t r a n s f e r a r e decoupled, and the t e m p e r a t u r e s of the r a d i a t i v e s u r f a c e a r e known or could be m e a s u r e d . In p r a c t i c e , h o w e v e r , it is doubtful that such a s s u m p tions a r e v a l i d . M o r e o v e r , the m e a s u r e m e n t of the D. L. REGOZO, formerly Graduate Student, University of New South Wales,is now Research Officer with the Australian Iron and Steel Pty. Ltd., Port Kembla, Australia. N. STANDISHMember AIME, is Associate Professor of Metallurgy,WollongongUniversity College, Wollongong,New South Wales, Australia. N. A. WARNER, formerly Associate Professor, University of New South Wales, is now Manager, Process Research, International Nickel Ltd. at Clydach, United Kingdom. Manuscript submitted April 10, 1972. METALLURGICALTRANSACTIONS
t e m p e r a t u r e s of the r a d i a t i v e s u r f a c
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