Question

3-20 Complete this table for H,O: P, kPa T, °C Phase description u, kJ/kg 400 1450 Saturated vapor 220 190 2500 4000 3040 C

Answer 1

Using steam tables, we get the following results based on calculations:

When P = 400 kPa and u = 1450 kJ/kg, we find that the steam is saturated at 143.62 deg C approx, with a quality of 0.4343.

When saturated vapour is taken at 220 deg C, the saturation pressure is 2319.8 kPa and u is 940.9 and 2600.3 (both in kJ/kg) respectively for saturated liquid and saturated vapour. Depending upon the quality of the steam, exact value of internal energy (u) can be calculated.

When P = 2500 kPa and T = 190 deg C, the steam is saturated and the values of are 806.1 kJ/kg and 2588.1 kJ/kg for saturated liquid and saturated vapour respectively. Depending upon the quality of the steam, exact value of internal energy can be calculated.

When P = 4000 kPa, for u = 3040 kJ/kg we have superheated steam at T = 465.4 deg C approximately.