01. Questions (a) to G) are \"drill\" problems meant to help you familiarize you
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01. Questions (a) to G) are "drill" problems meant to help you familiarize yourself with the thermodynamic tables. All these questions involve either reading off values or interpolating between given values to determine the unknown parameters. For each question: First deduce in which region of the p-o and T- u diagrams does the system lie (liquid? liquid-vapor? vapor?), explaining briefly how you arrived at your conclusion. Indicate in words the state of the system ('superheated vapor', etc.). State the appropriate table to use and using this table, determine the missing quantities asked for in the question. Draw an approximate (not to scale) sketch showing the state of the system in both the p-v and T-u diagrams. Your sketch should indicate the vapor dome, the relevant isobar and isotherm. I abel the ‘f' and ‘g' points. Write down the specific volume at the saturated liquid (f) and saturated vapor states Note: If you think the given data is insufficient to determine the unknown quantity, explain in a sentence or two why and state what further information you would need to complete the calculation. ° (a) p = 7.5 MPa, T 140C, u = ? (b) p = 6 MPa, u = 0.045 m/kg, T-? [Hint: For a given pressure, how do you find out whether the given value of u lies inside the vapor dome? Think about where the isobar intersects the vapor dome.] (c) p-3.0 bar, T = 133.6°C, u (d) T-60°C, u = 1.0172 x 10-3 m'/kg,p = ? (e) p-22.09 MPa, u = 3.155 x 10-3 mi/kg, T-7 (f) p=10 MPa, u=500 kJ/kg, T = ? (g) T-200C, p= 15.54 bar, x=0.4, u = ? (h) p-3 bar, u-2860 kJ/kg, T- (i) T=120°C for a saturated liquid-vapor mixture, x-I,-? G) p-16 MPa, u-3000 kJ/kg, v?Explanation / Answer
The problems are solved using the mollier chart and the steam tables. since 2 properties are given the other property can be read from the chart or extrapolated from the steam tables.
e) The mixture is super critical vapour, the temperature canno t be determined with given data i.e steam tables and mollier diagram.
g) v= vf + x* (vg - vf)= 1.156*10^-3 + 0.4 (0.127 - 1.156*10^-3)= 0.05149 m3/kg
The vf and vg values are obtained from the saturated state steam tables
h) Superhreated vapour at 197.11 C from the superheated state steam tables
i) Enthalpy = 2705.9 KJ/kg
j) Superheated vapour v= 0.015 m3/kg
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