TITLE.PM5

318 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-1.PM5 (^5) s 290 K^4 T 1200 K^2 Infinite source 1 3 6 290 K 400 K 647 K T Gas 2 ...

AVAILABILITY AND IRREVERSIBILITY 319 DHARM M-therm\Th6-2.PM5 δs Unavailable energy Available energy s p = 1 atm. T T = 279 K 0 T ...

320 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-2.PM5 Surrounding temperature, T 0 = 300 K Specific heat of water, cp = 4.187 k ...

AVAILABILITY AND IRREVERSIBILITY 321 DHARM M-therm\Th6-2.PM5 (ii) Heat transferred during cooling Q = m × cp × (T 1 – T 0 ) = 5 ...

322 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-2.PM5 = 85.4 – 288 × 0.061 = 67.8 kJ/kg ∴ Minimum work required 25 678 60 ×. = ...

AVAILABILITY AND IRREVERSIBILITY 323 DHARM M-therm\Th6-2.PM5 Change in entropy of oxygen = RO 2 loge v v 2 1 = 259.6 loge 19.874 ...

324 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-2.PM5 or 20(90 – t) = 30 (t – 30) ∴ t = 20 90 30 30 20 30 ×+× + = 54°C Total ma ...

AVAILABILITY AND IRREVERSIBILITY 325 DHARM M-therm\Th6-2.PM5 Loss in availability : Consider one kg of oil. Heat lost by oil = H ...

326 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-2.PM5 Let Tc = common temperature when heat flows between ice and water stops. ...

AVAILABILITY AND IRREVERSIBILITY 327 DHARM M-therm\Th6-2.PM5 the water evaporates at 200°C. The unavailable energy becomes the a ...

328 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-2.PM5 i.e., Possible work of heat engine = (h 2 – h 1 ) × 0.837 The possible wo ...

AVAILABILITY AND IRREVERSIBILITY 329 DHARM M-therm\Th6-2.PM5 = 0.6[50.25 – 42.38] = 4.722 kJ/kg ∴ Effectiveness = Increase of av ...

330 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-2.PM5 (ii)The change in availability : The change in availability is given by, ...

AVAILABILITY AND IRREVERSIBILITY 331 DHARM M-therm\Th6-2.PM5 O Q P P P P P P P P (i) From the property relation, TdS = dH – Vdp ...

332 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-2.PM5 (i)The irreversibility ; (ii)The effectiveness. Take for air : cp = 1.005 ...

AVAILABILITY AND IRREVERSIBILITY 333 DHARM M-therm\Th6-2.PM5 Example 6.20. A flywheel whose moment of inertia is 0.62 kg m^2 rot ...

334 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-2.PM5 If N 2 is the final r.p.m. of the flywheel, then ω 2 2 π^2 60 = N or N 2 ...

AVAILABILITY AND IRREVERSIBILITY 335 DHARM M-therm\Th6-2.PM5 Reversible/theoretical work which must be available, Wrev = 210.58 ...

336 ENGINEERING THERMODYNAMICS DHARM M-therm\Th6-2.PM5 1 2 ′ 2 s s= s 12 T Fig. 6.14 (i)Isentropic efficiency : ηisen. = Actual ...

AVAILABILITY AND IRREVERSIBILITY 337 DHARM M-therm\Th6-2.PM5 Energy is said to be degraded each time it flows through a finite ...