How To Calculate Flow Rate Of Chiller

Chiller Flow Rate Formula:

\[ Flow\ Rate\ (GPM) = \frac{Capacity\ (tons) \times 24}{\Delta T\ (°F)} \]

Flow Rate (GPM):

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1. What is Chiller Flow Rate?

Chiller flow rate refers to the volume of water circulated through a chiller system per unit time, typically measured in gallons per minute (GPM). It is a critical parameter for proper chiller operation and efficiency.

2. How Does the Calculator Work?

The calculator uses the chiller flow rate formula:

\[ Flow\ Rate\ (GPM) = \frac{Capacity\ (tons) \times 24}{\Delta T\ (°F)} \]

Where:

\( Capacity \) — Chiller cooling capacity in tons
\( \Delta T \) — Temperature difference across the chiller in °F
\( 24 \) — Conversion factor (1 ton of refrigeration = 12,000 BTU/hr = 24 GPM per °F)

Explanation: The formula calculates the required water flow rate based on the chiller's cooling capacity and the desired temperature difference across the system.

3. Importance of Flow Rate Calculation

Details: Proper flow rate calculation ensures efficient heat transfer, prevents equipment damage from low flow, and avoids energy waste from excessive flow. It helps in sizing pumps, pipes, and other system components correctly.

4. Using the Calculator

Tips: Enter chiller capacity in tons and temperature difference in °F. Both values must be positive numbers. Typical ΔT values range from 8°F to 12°F for standard chiller applications.

5. Frequently Asked Questions (FAQ)

Q1: Why is the constant 24 used in the formula?
A: The constant 24 comes from the conversion: 1 ton of refrigeration = 12,000 BTU/hr, and it takes 500 BTU to raise 1 gallon of water by 1°F in 1 hour, so 12,000 ÷ 500 = 24 GPM per °F.

Q2: What is a typical flow rate for chillers?
A: Typical flow rates range from 2-3 GPM per ton for standard applications, depending on the ΔT. With 10°F ΔT, the flow rate is approximately 2.4 GPM per ton.

Q3: How does ΔT affect flow rate?
A: Higher ΔT allows for lower flow rates, which can reduce pump energy consumption. Lower ΔT requires higher flow rates to achieve the same cooling capacity.

Q4: Can this formula be used for metric units?
A: For metric units (kW and °C), the formula becomes: Flow Rate (L/s) = Capacity (kW) × 0.86 ÷ ΔT (°C).

Q5: What happens if flow rate is too low or too high?
A: Too low flow can cause freezing, poor heat transfer, and chiller shutdown. Too high flow can cause erosion, excessive pressure drop, and wasted pump energy.