Ciclo termodinamico, aiuto per favore.

n = 3 mol;

R = 0,0821 atm dm^3 / mol K; oppure 8,314 Pa m^3 /molK.

TC = 200°C + 273 = 473 K;

PC = PB = 5 atm = 5 * 1,013 * 10^5 = 5,065 * 10^5 Pa;

PC * VC = n R TC;

VC = 3 * 0,0821 * 473 / 5 = 23,3 dm^3;

Isoterma AB; TB = TA;   PB = 5 atm;   VA = 10 dm^3;

PB * VB = PA * VA;   

5 * VB = PA * 10;

isobara BC; TC = 200°C + 273 = 473 K;

PC = PB = 5 atm; P costante; VC = 23,3 dm^3

VC / TC = VB / TB; 

23,3 /473 = VB / TB;

adiabatica; PC = 5 atm; VD = 30 dm^3; VC = 23,3 dm^3;

gamma = 7/5  per gas biatomico; n = 3 mol;

PC * VC^(gamma) = PD * VD^(gamma);  (1)

5 * VC^(7/5) = PD * 30^(5/3);  

5 * 23,3 ^(7/5) = PD * 30^(7/5);

PD = 5 * [(23,3/30)] ^(7/5) = 5 * (0,7767)^1,4;

PD = 5 *  3,51 atm; (pressione in D); 

gamma - 1 = 7/5 - 1 = 2/5;

TC * VC^(2/5) = TD * VD^(2/5);  (2)

473 * VC^(2/5) = TD * 30^(2/5);

(1 - gamma) / gamma = (1 - 7/5) / (7/5) = (- 2/5) * (5/7) = - 2/7 = - 0,2857;

TC * PC^(-0,286) = TD * PD^(- 0,2857);  (3)

473 * 5^(- 0,286) = TD * 3,51^(-0,2857);

TD = 473 * [(5/3,51)]^(-0,2857) = 473 * 0,904 = 428 K

isobara DA;  PD = PA;  VD = 30 dm^3;  TD = 428 K; VA = 10 dm^3

VA / TA = VD / TD;

TA / TD = VA / VD

TA = 10 * 428 / 30  ;

TA = 143 K.

TB = TA  = 143 K;  (isoterma) ;  PB = PC = 5 atm;

VB = n R TB / PB;

VB = 3 * 0,0821 * 143  / 5 = 7,04 dm^3;

PB * VB = PA * VA;   (isoterma  AB)

5 * 7,04  = PA * 10;

PA = 5 * 7,04 / 10 = 3,52 atm.

Rendimento massimo η (eta di Carnot);

η = (T max - T min) / Tmax;

η = (473 - 143) / 473 = 0,70;

η = 70 %