Evaporation Rate Calculator Water

Evaporation Rate Equation:

\[ E = C \times A \times (P_s - P_a) \]

Coefficient (C):

kg/h·m²·kPa

Area (A):

m²

Saturation Pressure (Pₛ):

kPa

Partial Pressure (Pₐ):

kPa

Evaporation Rate (E):

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1. What is the Evaporation Rate Equation?

The evaporation rate equation calculates the mass of water evaporating per unit time from a surface. It's used in environmental engineering, chemical processes, and hydrology to estimate water loss from reservoirs, cooling towers, and other systems.

2. How Does the Calculator Work?

The calculator uses the evaporation rate equation:

\[ E = C \times A \times (P_s - P_a) \]

Where:

\( E \) — Evaporation rate (kg/h)
\( C \) — Mass transfer coefficient (kg/h·m²·kPa)
\( A \) — Surface area (m²)
\( P_s \) — Saturation vapor pressure at water temperature (kPa)
\( P_a \) — Partial pressure of water vapor in air (kPa)

Explanation: The equation calculates the evaporation rate based on the vapor pressure difference (driving force) and the mass transfer characteristics of the system.

3. Importance of Evaporation Rate Calculation

Details: Accurate evaporation rate estimation is crucial for water resource management, cooling system design, chemical process engineering, and environmental impact assessments.

4. Using the Calculator

Tips: Enter all values in consistent units (kg/h·m²·kPa for coefficient, m² for area, kPa for pressures). The coefficient depends on wind speed, temperature, and surface characteristics.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for the coefficient C?
A: Typical values range from 0.1 to 0.5 kg/h·m²·kPa for natural water surfaces, depending on wind speed and temperature.

Q2: How do I determine saturation vapor pressure?
A: Saturation vapor pressure can be calculated from water temperature using the Antoine equation or obtained from steam tables.

Q3: What affects evaporation rate the most?
A: The vapor pressure difference (Pₛ - Pₐ) is the primary driver, followed by surface area and wind speed (which affects C).

Q4: Can this be used for other liquids?
A: The same principle applies, but the coefficient and vapor pressure characteristics will differ for other liquids.

Q5: How accurate is this calculation?
A: It provides a reasonable estimate but actual rates may vary due to factors like surface contamination, wind patterns, and temperature gradients.