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Thermodynamic analysis of optimal condensing* D* X ^- F P; c9 A8 l; D
temperature of cascade-condenser in CO2/NH3
0 n$ m1 H9 ?2 `4 lcascade refrigeration systems T2 H& G" s9 K
Tzong-Shing Lee*,1( Q$ g9 T1 I+ Q/ D0 q- }' w
, Cheng-Hao Liu, Tung-Wei Chen8 q1 n4 e. e6 N. N. Y
Department of Air-Conditioning and Refrigeration Engineering, National Taipei University of Technology,* c3 T7 d& m- c% T: j# S: L* a1 ]- j
No. 1, Sec. 3, Chung-Hsiao East Road, Taipei 106, Taiwan% e* [8 V2 o" r, h3 i1 p v
Received 10 November 2005; received in revised form 6 March 2006; accepted 6 March 2006: S% o& H1 R0 F$ r: ^9 a+ ^4 t0 g* u
Available online 5 June 2006
$ o* }6 D" z! j; K' U sAbstract
3 U8 @- |4 R8 N, j% |0 rThis study thermodynamically analyzed a cascade refrigeration system that uses carbon dioxide and ammonia as refriger-7 d2 `2 K, t3 c0 p! z M$ P( }! b0 g: M
ants, to determine the optimal condensing temperature of the cascade-condenser given various design parameters, to maximize# f1 w" X' q ^0 u' E1 r" G$ _
the COP and minimize the exergy destruction of the system. The design parameters include: the evaporating temperature, the O) M! w* `: N5 @) \/ E) r# I# V/ z
condensing temperature and the temperature difference in the cascade-condenser. The results agreed closely with the reported9 x' k r. f u0 x9 S( @4 P
experimental data. The optimal condensing temperature of the cascade-condenser increases with TC, TE and DT. The maximum
& A @+ ], w$ N; M' T3 b' ACOP increases with TE, but decreases as TC or DT increases. Two useful correlations that yield the optimal condensing temper-- i; {1 H& p; F$ a0 Y2 E
ature of the cascade-condenser and the corresponding maximum COP are presented.
/ ~( q+ D7 A$ a$ i* ^$ D 2006 Elsevier Ltd and IIR. All rights reserved." L8 e6 d* y0 {1 b8 p
Keywords: Refrigeration system; Compression system; Cascade system; Ammonia; Carbon dioxide; Optimization; Temperature; Condensa-/ v; X- b( |# ]4 v. ^' g2 k
tion; COP |
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发表于 2009-9-6 11:19:10
