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Unformatted text preview: . 2 MPa and heated. The initial volume is 0 . 0277 m 3 and the ﬁnal volume is 0 . 0307 m 3 . (a) What are the initial and ﬁnal temperatures of the propane? (b) What is the work done by the system? (c) What is the change in internal energy of the system? 2 3 (10 points) A hot water heater operates in steady state. A mass ﬂux ˙ m 1 of cold water enters and is heated by an electrical resistance; ˙ m 2 of hot water leaves the heater. Deﬁne a control volume just inside the heater and inlet/outlet sections 1 and 2 respectively. Neglect kinetic and potential energy effects. (a) Is work done on the control volume? (b) If the heater is well insulated, show that h 2 = h 1 + ˙ W in / ˙ m . What are h and ˙ m ? (c) If the water is taken to be incompressible with constant speciﬁc heat c and constant speciﬁc volume v , ﬁnd an expression for T 2 in terms of T 1 , c , ˙ W in , v and Q , the volumetric ﬂow rate. 3...
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This note was uploaded on 04/01/2009 for the course MAE mae 110a taught by Professor ? during the Fall '07 term at UCSD.
- Fall '07