Since the P e l t i e r e f f e c t i s r e v e r s i b l e i n c h a r a c t e r , a t h e r m o e l e c t r i c chamber can be operated either as a cooling or heating device depending on t h e d i r e c t i o n o f i n p u t c u r r e n t f l o w . U t i l i z i n g t h i s r e v e r s i b l e e f f e c t , t h e i n t e r n a l chamber temperature, which surrounds temperature sensitive components such as q u a r t z c r y s t a l s and c r y s t a l o s c i l l a t o r s , c a n be c o n t r o l l e d and maintained a t 25OC as t h e e x t e r n a l ambient temperature varies either above o r below t h e c o n t r o l l e d t e m p e r a t u r e p o i n t . S i n c e t h e c r y s t a l i s a b l e t o o p e r a t e a t a lower average temperature, the aging rate w i l l be lower and improved frequency temperature stability and reduced average power consumpt i o n c a n r e s u l t u n d e r c e r t a i n o p e r a t i n g c o n d i t i o n s . I n t h e d e s i g n o f a t h e r m o e l e c t r i c chamber, the parameters that are of p r imary importance are shown t o be f i g u r e o f merit 2 of the material, heat l e a k i n t o t h e chamber and temperature r i s e of f i n above ambient. It i s found t h a t by u t i l i z i n g a pyrex dewar f l a s k as the inner-core enclosure h e a t l e a k i s considerably reduced, thus, smaller s i z e , less number of couples and lower input power c a n b e r e a l i z e d f o r a chamber design. Temperature difference, AT, between the inside and outside of a chamber i s shown t o be influenced by t h e r i p p l e of the d-c input current. P r a c t i c a l i n p u t c u r r e n t ranges f o r chamber d e s i g n s a r e d i s c u s s e d . Thermostat temperature control used in conjunction with a s t a t i c d-c t o d-c power c o n v e r t e r i s described. Although t h e P e l t i e r e f f e c t h a s b e e n known f o r 128 years, i t has only been i n r e c e n t y e a r s t h a t p r a c t i c a l c o o l i n g d e v i c e s have become p o s s i b l e w i t h the development and manufacture of high performance semiconductor materials. The P e l t i e r e f f e c t c a n b e s t be described when c u r r e n t passes through two d i s s i m i l a r materials t h a t are joined together a t t h e i r e n d s ; h e a t i s absorbed a t one j u n c t i o n and r e l e a s e d at t h e o t h e r .Figure 1 shows the basic element of a t h e r m o e l e c t r i c c o o l i n g o r h e a t pumpi n g device, the thermoelectric couple. The t h e r m o e l e c t r i c c o u p l e c o n s i s t s of two "arms," one of 'n' and the other of 'p' type semiconductor material j o i n e d t o g e t h e r a t one end by a c o p p e r s t r a p and connected a t t h e o t h e r ends by copper straps t o an external c u r r e n t source. When c u r r e n t I passes through the couple, the majority carriers ( e l e c t r o n s and p o s i t i v e holes) experience a change i n p o t e n t i a l and k i n e t i c e n e r g i e s i n c r o s s i n g the c o n t a c t s or juncti...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.