1. What is Enthalpy of Compressed Water?

The enthalpy of compressed water represents the total energy content per unit mass, accounting for both internal energy and flow work. It's a fundamental property in thermodynamics for analyzing energy transfer in systems involving water under pressure.

2. How Does the Calculator Work?

The calculator uses the enthalpy equation:

Where:

• \( h \) — Enthalpy (J/kg)
• \( u \) — Internal energy (J/kg)
• \( p \) — Pressure (Pa)
• \( v \) — Specific volume (m³/kg)

Explanation: The equation accounts for both the internal energy of the water and the work required to maintain the water at constant pressure.

3. Importance of Enthalpy Calculation

Details: Enthalpy is crucial for analyzing thermodynamic processes in power plants, refrigeration systems, and other engineering applications where water is used as a working fluid under pressure.

4. Using the Calculator

Tips: Enter internal energy in J/kg, pressure in Pascals, and specific volume in m³/kg. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between enthalpy and internal energy?
A: Enthalpy includes both internal energy and the flow work (pV term), making it more useful for analyzing open systems at constant pressure.

Q2: What are typical enthalpy values for water?
A: For liquid water at 1 atm and 25°C, enthalpy is about 104.9 kJ/kg. Values increase with temperature and pressure.

Q3: When is this calculation most useful?
A: For analyzing energy changes in pumps, turbines, heat exchangers, and other devices where water is compressed or expanded.

Q4: Does this work for steam as well as liquid water?
A: Yes, the equation applies to all phases, but you must use appropriate u and v values for the phase condition.

Q5: How does compression affect water enthalpy?
A: Increasing pressure generally increases enthalpy, though the effect is more significant for steam than for liquid water.