This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: ME 326H: THERMODYNAMICS I Test 1, Feb. 23, 1996 1) (28%) A substance is inside a piston/cylinder system. Initially, the substance is at T 1 =150C and P 1 =10 kPa. The piston is moved to compress the substance isothermally until P 2 =100 kPa. a) If the substance is argon, what is the change in the specific internal energy of the argon, u 2u 1 (kJ/kg)? b) If the substance is argon, how much heat transfer 1 q 2 (kJ/kg) occurred? c) If the substance is steam, what is the change in the specific internal energy of the steam, u 2u 1 (kJ/kg)? d) If the substance is steam, describe in a few sentences how you could calculate how much heat transfer 1 q 2 (kJ/kg) occurred. SOLUTION: a): Argon acts as an ideal gas, for which u=u(T only), so for an isothermal process, u=0 . b): First Law for CM is 1 q 2 1 w 2 =u 2u 1 =0, so 1 q 2 = 1 w 2 so 1 q 2 = 1 w 2 = Pdv v v = RT dv v v v = RT ln v 2 v 1 = RT ln P 1 P 2 = 0.20813 423 ln0.1 =202.7 kJ/kg c): From Table D.12, u 1 =2587.4 kJ/kg; u 2 =2582.4 kJ/kg, so u 2 u...
View Full
Document
 Spring '07
 Schmidt

Click to edit the document details