Overall Heat Transfer Coefficient Given By-Pass Factor Calculator

Formula Used:

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

By Pass Factor (BPF):

(unitless)

Mass of Air:

Specific Heat Capacity:

J/kg·K

Surface Area of Coil:

m²

Overall Heat Transfer Coefficient (U):

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1. What is the Overall Heat Transfer Coefficient?

The Overall Heat Transfer Coefficient (U) is a measure of the overall convective heat transfer between a fluid medium and the surface flowed over by the fluid. It represents the heat transfer rate per unit area per unit temperature difference.

2. How Does the Calculator Work?

The calculator uses the formula:

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

Where:

\( BPF \) — By Pass Factor (unitless)
\( m_{air} \) — Mass of Air (kg)
\( c \) — Specific Heat Capacity (J/kg·K)
\( A_c \) — Surface Area of Coil (m²)

Explanation: The formula calculates the overall heat transfer coefficient based on the by-pass factor, mass of air, specific heat capacity, and surface area of the coil.

3. Importance of Overall Heat Transfer Coefficient

Details: The overall heat transfer coefficient is crucial in designing and analyzing heat exchangers, HVAC systems, and other thermal systems. It helps in determining the efficiency of heat transfer processes and optimizing system performance.

4. Using the Calculator

Tips: Enter the by-pass factor (between 0 and 1), mass of air, specific heat capacity, and surface area of the coil. All values must be positive and valid.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of By Pass Factor?
A: The by-pass factor typically ranges between 0 and 1, where 0 indicates perfect heat transfer and 1 indicates no heat transfer.

Q2: How does mass of air affect the heat transfer coefficient?
A: Higher mass of air generally increases the heat transfer rate, leading to a higher overall heat transfer coefficient.

Q3: What units should be used for specific heat capacity?
A: Specific heat capacity should be in J/kg·K for consistent results with the formula.

Q4: Why is the natural logarithm used in the formula?
A: The natural logarithm accounts for the exponential relationship between the by-pass factor and the heat transfer process.

Q5: Can this calculator be used for liquids other than air?
A: While primarily designed for air, the calculator can be adapted for other fluids by adjusting the specific heat capacity value accordingly.