1. What is a Cooling Coil Sizing Calculator?

Definition: This calculator estimates the required heat transfer surface area of a cooling coil based on heat load, overall heat transfer coefficient, and log mean temperature difference.

Purpose: It helps HVAC engineers and technicians properly size cooling coils for air conditioning and refrigeration systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( A \) — Cooling coil area (m²)
• \( Q \) — Heat load (watts)
• \( U \) — Overall heat transfer coefficient (W/m²°C)
• \( \Delta T_{lm} \) — Log mean temperature difference (°C)

Explanation: The heat load is divided by the product of the heat transfer coefficient and temperature difference to determine the required surface area.

3. Importance of Cooling Coil Sizing

Details: Proper coil sizing ensures efficient heat transfer, optimal system performance, and energy efficiency in HVAC systems.

4. Using the Calculator

Tips: Enter the heat load in watts, overall heat transfer coefficient (default 30 W/m²°C), and log mean temperature difference (default 10°C). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical U value for cooling coils?
A: Typical values range from 25-50 W/m²°C depending on coil type, fluid velocities, and materials.

Q2: How do I calculate log mean temperature difference?
A: ΔT_lm = [(T₁-t₂)-(T₂-t₁)]/ln[(T₁-t₂)/(T₂-t₁)] where T=fluid temp, t=air temp.

Q3: What affects the heat transfer coefficient?
A: Fluid type, velocity, coil material, fin spacing, and surface conditions all affect U values.

Q4: Should I include a safety factor?
A: Yes, typically add 10-20% to the calculated area for fouling and design margins.

Q5: Can this be used for heating coils?
A: Yes, the same formula applies for heating coil sizing calculations.