MECHENG 235 Study Guide - Midterm Guide: Superheating, Polytropic Process, Joule
29 Apr 2014
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Me 235 exam i , oct 19, 2011: kurabayashi and d. siegel, me dept. Exam rules: open book and one page of notes allowed. I have observed the honor code and have neither given nor received aid on this exam. It is now compressed via a polytropic process with pvn = constant (n 1) to a final temperature of 500k (state 2). The work done during the process is -80 kj. At t = 120 k, p= psat = 2513 kpa, x = (h hf)/hfg = 0. 8444 u = uf +x ufg = 42. 29 kj/kg (c) table b. 4. 1 at 20 c, v = vg = 0. 0648 m3/kg => saturated vapor. At t = -20 c, p= psat = 399. 6 kpa u = ug = 245. 99 kj/kg (d) table b. 1. 2 since u > ug => superheated vapor . From table b. 1. 3, t = 300 c v = 0. 52256 m3/kg (a) ideal gas:
