Mass Of Air Passing Over Coil Given By-Pass Factor Calculator

Formula Used:

\[ m_{air} = -\frac{U \times A_c}{c \times \ln(BPF)} \]

Overall Heat Transfer Coefficient (U):

W/m²·K

Surface Area of Coil (A_c):

m²

Specific Heat Capacity (c):

J/kg·K

By Pass Factor (BPF):

Mass of Air (m_air):

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1. What is the Mass of Air Passing Over Coil?

The mass of air passing over a coil is a measure of the amount of air flowing through a heat exchanger system. It is calculated based on the heat transfer characteristics and the bypass factor of the coil.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ m_{air} = -\frac{U \times A_c}{c \times \ln(BPF)} \]

Where:

\( U \) — Overall heat transfer coefficient (W/m²·K)
\( A_c \) — Surface area of coil (m²)
\( c \) — Specific heat capacity (J/kg·K)
\( BPF \) — By pass factor (dimensionless, between 0 and 1)

Explanation: This formula calculates the mass flow rate of air based on the heat transfer properties and the efficiency of the coil represented by the bypass factor.

3. Importance of Mass of Air Calculation

Details: Calculating the mass of air passing over a coil is essential for designing and optimizing HVAC systems, ensuring proper heat exchange efficiency, and maintaining desired temperature conditions in various applications.

4. Using the Calculator

Tips: Enter the overall heat transfer coefficient in W/m²·K, surface area in m², specific heat capacity in J/kg·K, and bypass factor (between 0 and 1). All values must be positive, with bypass factor strictly between 0 and 1.

5. Frequently Asked Questions (FAQ)

Q1: What is the bypass factor?
A: The bypass factor represents the inability of a coil to cool or heat the air to its temperature, indicating the fraction of air that bypasses the coil without being affected.

Q2: Why is the natural logarithm used in the formula?
A: The natural logarithm (ln) is used to account for the exponential relationship in the heat transfer process and the bypass factor's effect on mass flow calculation.

Q3: What are typical values for bypass factor?
A: Bypass factor typically ranges from 0.05 to 0.25 for well-designed coils, with lower values indicating better coil performance.

Q4: How does specific heat capacity affect the result?
A: Specific heat capacity represents the amount of heat required to raise the temperature of air. Higher specific heat capacity results in lower mass flow rate for the same heat transfer.

Q5: What units should be used for inputs?
A: Use consistent SI units: W/m²·K for heat transfer coefficient, m² for surface area, J/kg·K for specific heat capacity, and dimensionless for bypass factor.