Question

Analyzine three processes in Series Water contained in a piston-cylinder assembly undergoes three processes in series from an initial state wher the pressure is 10 bar and 500 ∘C (ref example 3.4)(10 points) - Process 1-2. The water is cooled as it is compressed at a constant pressure of 10 bar to the saturated vapor state. - Process 2-3 the water is cooled at constant volume to 150 ∘ C - Process 3-4 the water expands at a constant temperature of 150 ∘ C to saturated vapor a. Sketch all processs on T−v and p−v diagrams

Answer 1

Thermodynamic processes involving water in a piston-cylinder can be visualized on T-v and p-v diagrams. Process 1-2 is a constant pressure cooling, process 2-3 is cooling at constant volume, and process 3-4 is isothermal expansion to saturated vapor. These processes are depicted as horizontal and vertical lines on the diagrams, representing constant pressure, constant volume, and constant temperature transformations.

Step-by-step explanation:

To analyze the thermodynamic processes of water in a piston-cylinder assembly, it's essential to sketch the transformations on T-v and p-v diagrams. Starting at an initial state with a pressure of 10 bar and 500 °C, the following steps describe each process:

1. Process 1-2: Water is cooled at a constant pressure of 10 bar until it reaches the saturated vapor state. On a T-v diagram, this process is represented by a horizontal line to the left until it hits the saturated vapor curve. On a p-v diagram, it's also a horizontal line since the pressure remains constant as the water cools and volume decreases until reaching the saturated vapor state.
2. Process 2-3: Water is further cooled at a constant volume until it reaches 150 °C. This is shown as a vertical line downward on a T-v diagram since the volume remains unchanged and the temperature decreases. On a p-v diagram, it's a vertical line downward, representing a reduction in pressure at constant volume.
3. Process 3-4: The water then expands at a constant temperature of 150 °C until it returns to saturated vapor. This expansion at constant temperature is shown as a horizontal line to the right on a T-v diagram until it meets the saturated vapor curve again. The p-v diagram will show an increase in volume along an isothermal curve.

In a phase diagram, starting at a high temperature and pressure point, cooling at constant pressure moves the point left until it hits the vapor curve, indicating the beginning of condensation. Constant volume cooling moves the point straight down, depicting a pressure drop. Finally, isothermal expansion moves right along the constant temperature line until reaching the saturated vapor state.