Steam tables: example 1

This paragraph introduces a series of worked examples on calculating the thermodynamic properties of water, which is essential for analyzing steam power plants, air-conditioning systems, and any processes involving water in liquid or vapor states. The first example focuses on finding the internal energy of water at 240°C and 2000 kPa. The speaker advises drawing a phase diagram, specifically a temperature-volume diagram, to visualize the state of water. The process involves consulting the saturated water table to determine the saturation pressure at the given temperature, which is found to be 33.44 bar or 3344 kPa. The diagram helps to identify the state of water as superheated vapor because the given pressure is less than the saturation pressure. The state is graphically determined at the intersection of the constant temperature and constant pressure curves on the phase diagram.

The second paragraph continues the discussion on identifying the state of water as superheated vapor and emphasizes the importance of understanding this to select the correct table for further calculations. The speaker explains that since the pressure is below the saturation pressure, the state is confirmed as superheated vapor. The process then involves referring to the superheated vapor table, which is organized by pressure. Fortunately, there is a specific table for the exact pressure of 2000 kPa (2 MPa), and within this table, a row for 240°C is available. The internal energy (u) of the superheated vapor at these conditions is found to be 2659.6 kJ/kg, which is the specific internal energy value needed for the analysis. The summary concludes with the final answer, including the units, providing a clear and concise result for the example problem.