TITLE.PM5

258 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-3.pm5 It remains unchanged in all adiabatic frictionless processes. It increa ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 259 dharm /M-therm/th5-3.pm5 s 1 T 1 T 2 s 2 s Q 2 v = Const. T 1 = cv loge p p 2 1 + ( ...

260 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-3.pm5 5.17.3. Heating a gas at constant pressure Refer Fig. 5.26. Let 1 kg of ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 261 dharm /M-therm/th5-3.pm5 Fig. 5.27. T-s diagram : Isothermal process. ∴ T(s 2 – s 1 ...

262 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-3.pm5 5.17.6. Polytropic process Refer Fig. 5.29. The expression for ‘entropy ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 263 dharm /M-therm/th5-3.pm5 = cv loge T T 2 1 R 1 n− 1 F HG I KJ loge T T 2 1 = cv l ...

264 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-3.pm5 In other words, heat absorbed approximately equals the product of change ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 265 dharm /M-therm/th5-3.pm5 If equation (5.37) is divided by dt, then it becomes a rat ...

266 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-3.pm5 However, at temperatures above absolute zero, the entropy is a function ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 267 dharm /M-therm/th5-3.pm5 Solution. Change in entropy during constant volume process ...

268 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-3.pm5 For a perfect gas at constant volume, p T p T 1 1 2 2 = 4.05 293 5 2 = ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 269 dharm /M-therm/th5-3.pm5 Solution. Refer Fig. 5.32. Initial pressure, p 1 = 1.05 ba ...

270 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-3.pm5 Now, using characteristic gas equation (to find mass ‘m’ of nitrogen), w ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 271 dharm /M-therm/th5-3.pm5 ∆U = 0, Q = W i.e., Qpdv v v =z. 1 2 = RT v dv v v . 1 2 z ...

272 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-3.pm5 Characteristics gas constant, R = R M (^0) =^8314 44 = 189 Nm/kg K To fi ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 273 dharm /M-therm/th5-4.pm5 Fig. 5.35 or T 2 = 873 ×^105 7 025 . 125 . F. HG I KJ = 87 ...

274 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-4.pm5 Note that if in this problem sA – s 2 happened to be greater than sA – s ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 275 dharm /M-therm/th5-4.pm5 ∴ T 2 = 733 × 1. 0.4 012 1.4 7 F HG I KJ = 733 × (0.1446)0 ...

276 ENGINEERING THERMODYNAMICS dharm /M-therm/th5-4.pm5 (i)Change in enthalpy, H 2 – H 1 : We know that, H dH Vdp H p p 1 2 1 2 ...

SECOND LAW OF THERMODYNAMICS AND ENTROPY 277 dharm /M-therm/th5-4.pm5 (v)Work transfer, W1–2 : Q1–2 = (U 2 – U 1 ) + W1–2 ∴ W1–2 ...