Question

PROBLEM 4 Ammonia is heated in a closed, rigid container of volume 2 m'. It is initially a saturated vapor at 2°C and heated to a final temperature of 20°C. Determine the following: (a) Initial and final mass of the system of ammonia (b) Specific volume and pressure for initial state (state 1) (c) Specific volume and pressure for final state (state 2) (d) Show states 1 and 2 on a P-v diagram. (Clearly label the initial (1) and final (2) states, critical point (C.P.), and constant temperature line(s).)

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Answer 1

From saturated temperature tables, at Ti -2°C, the properties are as R Pt 6.1529 bar VI v, 0.2054 m' /kg Calculate the mass of ammonia: m9.737 kg Since, no mass transfer takes place in a closed svstem: m2m9.737 kg 0.2054 The pressure and specific volume at state (1) are: P Pt 6.1529 bar VI vg 0.2054 m' /kg The specific volume remains constant v2 0.2054 m' / kg Calculate the pressure corresponding to T 20°C and v20.2054m'/kg through interpolation from super heated tables 7-pp 0.18721-0.2054 7-6 0.18721-0.22155 p 6.47 bar

Draw the P -v diagram for ammonia. 20℃、 ② 6.1529 bar ....> 0.2054 m/kg Draw the T -v diagram for ammonia. 47 ba、 20°C 6.1529 bar 0.2054 mikg