Uma turbina opera adiabaticamente com vapor superaquecido sendo alimentado a T 1 e P 1 , com uma vazão mássica m ˙ . A pressão na exaustão é P 2 e a eficiência da turbina é η . Para um dos conjuntos de condições operacionais a seguir, determine a potência da turbina, a entalpia e a entropia do vapor na exaustão.

(a) T 1 = 450 ∘ C ; P 1 = 8.000 k P a ; m ˙ = 80   k g   s - 1 ; P 2 = 30 k P a ; η = 0,80 .(b) T 1 = 550 ∘ C ; P 1 = 9.000 k P a ; m ˙ = 90   k g   s - 1 ; P 2 = 20 k P a ; η = 0,77 (c) T 1 = 600 ∘ C ; P 1 = 8.600 k P a ; m ˙ = 70   k g   s - 1 ; P 2 = 10 k P a ; η = 0,82 .(d) T 1 = 400 ∘ C ; P 1 = 7.000 k P a ; m ˙ = 65   k g   s - 1 ; P 2 = 50 k P a ; η = 0,75 (e) T 1 = 200 ∘ C ; P 1 = 1.400 k P a ; m ˙ = 50   k g   s - 1 ; P 2 = 200 k P a ; η = 0,75 (f) T 1 = 900   ∘ F ; P 1 = 1.100 ( p s i a ) ; m ˙ = 150 l b m ( s ) - 1 ; P 2 = 2 ( p s i a ) ; η = 0,80 .(g) T 1 = 800   ∘ F ; P 1 = 1.000 ( p s i a ) ; m ˙ = 100   b m ( s ) - 1 ; P 2 = 4 ( p s i a ) ; η = 0,75 .

Passo 1

Os vetores a seguir contêm valores para as partes (a) a (g). Para condições de ingestão:

H 1 : = 3274.3 ⋅ k J k g 3509.8 ⋅ k J k g 3634.5 ⋅ k J k g 3161.2 ⋅ k J k g 2801.4 ⋅ k J k g 1444.7 ⋅ B t u l b m 1389.6 ⋅ B t u l b m S 1 : = 6.5597 ⋅ k J k g ⋅ K 6.8143 ⋅ k J k g ⋅ K 6.9813 ⋅ k J k g ⋅ K 1.6000 ⋅ B t u l b m ⋅  rankine  6.4536 ⋅ k J k g ⋅ K 1.5677 ⋅ B t u l b m ⋅  rankine  η : = 0.80 0.77 0.82 0.75 0.75 0.80 0.75

Para condições de descarga:

S l i q : = 0.9441 ⋅ k J k g ⋅ K 0.8321 ⋅ k J k g ⋅ K 0.6493 ⋅ k J k g ⋅ K 1.0912 ⋅ k J k g ⋅ K 0.1750 ⋅ B t u l b m ⋅ r a n k i n e 1.5301 ⋅ k J k g ⋅ K 0.2200 ⋅ B t u l b m ⋅  rankine  S v a p : = 7.7695 ⋅ k J k g ⋅ K 7.9094 ⋅ k J k g ⋅ K 7.1511 ⋅ k J k g ⋅ K 7.5947 ⋅ k J k g ⋅ K 7.1268 ⋅ k J k g ⋅ K 1.9200 ⋅ B t u l b m  \ rankine   1.8625 ⋅ B t u l b m ⋅  rankine  S 2 = S 1

H l i q : = 289.302 ⋅ k J k g 251.453 ⋅ k J k g 191.832 ⋅ k J k g 340.564 ⋅ k J k g 504.701 ⋅ k J k g 94.03 ⋅ B t u l b m 120.99 ⋅ B t u l b m H v a p : = 2625.4 ⋅ k J k g 2609.9 ⋅ k J k g 2584.8 ⋅ k J k g 2646.0 ⋅ k J k g 2706.3 ⋅ k J k g 1116.1 ⋅ B t u l b m 1127.3 ⋅ B t u l b m mdot   : = 80 ⋅ k g s e c 90 ⋅ k g s e c 70 ⋅ k g s e c 65 ⋅ k g s e c 50 ⋅ k g s e c 150 ⋅ l b m s e c 100 ⋅ l b m s e c

x 2 : = S 1 - S l i q → S vap  - S l i q H 2 : = H l i q + x 2 ' ⋅ H v a p - H l i q ) ¯

Δ H : = η ⋅ H 2 - H 1 ) → H 2 : = H 1 + Δ H Wdot   : = ( A H ) ⋅ m d o t →

x 2 : = H 2 - H l i q → H v a p - H l i q S 2 : = S l i q + x 2 ⋅ S v a p - S l i q ) ¯

H 2 1 H 2 2 H 2 3 H 2 4 H 2 5 = 2423.9 2535.9 2467.8 2471.4 2543.4 k J k g S 2 1 S 2 2 S 2 3 S 2 4 S 2 5 = 7.1808 ) 7.6873 7.7842 7.1022 6.7127 k J k g ⋅ K

H 2 6 H 2 7 = 1031.9 1057.4 B t u l b m S 2 6 S 2 7 =   1.7762 1.7484 B t u l b m ⋅  rankine 

Wdot   = - 68030 ) - 87653 - 81672 - 44836 - 12900 - 65333 - 35048 k W W d o t = - 91230 ) - 117544 - 109523 - 60126 - 17299 - 87613 - 46999 h p

Resposta

H 2 1 H 2 2 H 2 3 H 2 4 H 2 5 = 2423.9 2535.9 2467.8 2471.4 2543.4 k J k g S 2 1 S 2 2 S 2 3 S 2 4 S 2 5 = 7.1808 ) 7.6873 7.7842 7.1022 6.7127 k J k g ⋅ K

H 2 6 H 2 7 = 1031.9 1057.4 B t u l b m S 2 6 S 2 7 =   1.7762 1.7484 B t u l b m ⋅  rankine 

Wdot   = - 68030 ) - 87653 - 81672 - 44836 - 12900 - 65333 - 35048 k W W d o t = - 91230 ) - 117544 - 109523 - 60126 - 17299 - 87613 - 46999 h p