1. What is a Coil Heat Exchanger Calculator?

Definition: This calculator estimates the heat transfer rate in a coil heat exchanger based on the overall heat transfer coefficient, heat transfer area, and log mean temperature difference.

Purpose: It helps engineers and technicians determine the thermal performance of coil heat exchangers used in HVAC systems, industrial processes, and refrigeration.

2. How Does the Calculator Work?

The calculator uses the fundamental heat transfer equation:

Where:

• \( Q \) — Heat transfer rate (watts)
• \( U \) — Overall heat transfer coefficient (W/m²K)
• \( A \) — Heat transfer area (m²)
• \( \Delta T_{lm} \) — Log mean temperature difference (K)

Explanation: The heat transfer rate is directly proportional to the U-value, surface area, and the temperature difference driving force.

3. Importance of Heat Transfer Calculation

Details: Accurate heat transfer calculations ensure proper heat exchanger sizing, energy efficiency, and system performance in thermal applications.

4. Using the Calculator

Tips: Enter the U-value (typically 10-1000 W/m²K depending on fluids and materials), heat transfer area, and log mean temperature difference. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the log mean temperature difference?
A: ΔT_lm is the logarithmic average of the temperature differences between the hot and cold fluids at each end of the heat exchanger.

Q2: What's a typical U-value for water-to-water heat exchangers?
A: Typically 300-1500 W/m²K, depending on flow conditions and fouling factors.

Q3: How do I calculate ΔT_lm for counterflow?
A: ΔT_lm = [(T_h,in - T_c,out) - (T_h,out - T_c,in)] / ln[(T_h,in - T_c,out)/(T_h,out - T_c,in)]

Q4: Does this account for fouling factors?
A: No, fouling factors should be incorporated into the U-value before using this calculator.

Q5: Can I use this for other heat exchanger types?
A: The basic equation applies to all types, but ΔT_lm may need correction factors for complex configurations.