1. What is a Chilled Water Flow Rate Calculator?

Definition: This calculator determines the required chilled water flow rate in gallons per minute (GPM) based on heat load and temperature difference.

Purpose: It helps HVAC engineers and technicians properly size chilled water systems for cooling applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Chilled water flow rate (GPM)
• \( Q_{btu} \) — Heat load (BTU/hour)
• \( \Delta T \) — Temperature difference (°F)
• 500.4 — Constant (density × specific heat × conversion factor)

Explanation: The formula calculates how much water flow is needed to remove the specified heat load given the system's temperature difference.

3. Importance of Flow Rate Calculation

Details: Proper flow rate calculation ensures efficient system operation, prevents undersizing or oversizing, and maintains optimal heat transfer.

4. Using the Calculator

Tips: Enter the heat load in BTU/hour and the temperature difference in °F (default 10°F). Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical ΔT for chilled water systems?
A: Most systems are designed for 10-12°F ΔT, but some high-efficiency systems use 15-20°F.

Q2: Why is the constant 500.4?
A: It combines water's density (8.33 lb/gal), specific heat (1 BTU/lb-°F), and converts hours to minutes (60 min/h).

Q3: How do I find the heat load (Q_btu)?
A: Calculate from building cooling load or equipment specifications. 1 ton of cooling = 12,000 BTU/h.

Q4: Does this work for other fluids?
A: No, this formula is specific to water. Other fluids require different constants based on their properties.

Q5: What if my system uses °C instead of °F?
A: Convert ΔT to °F first (ΔT°F = ΔT°C × 1.8) before using this calculator.