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Chilled Water Flow Equation:
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The Chilled Water System Calculation determines the flow rate required in gallons per minute (GPM) based on cooling capacity in tons and temperature difference (ΔT). This is essential for designing and operating efficient HVAC systems.
The calculator uses the chilled water flow equation:
Where:
Explanation: The equation calculates the required water flow based on the heat transfer capacity and temperature differential, where 24 represents the conversion factor from tons to GPM considering water's specific heat.
Details: Accurate flow calculation is crucial for proper chiller sizing, pump selection, pipe sizing, and ensuring efficient heat transfer in HVAC systems. Incorrect flow rates can lead to poor system performance and energy inefficiency.
Tips: Enter cooling capacity in tons and temperature difference in °F. Typical ΔT values range from 10°F to 20°F for efficient system operation. All values must be positive numbers.
Q1: What is a typical ΔT for chilled water systems?
A: Most systems operate with ΔT between 10°F and 20°F. Higher ΔT values allow for lower flow rates and smaller pipes, improving efficiency.
Q2: Why is the constant 24 used in the formula?
A: The constant 24 comes from the conversion: 1 ton = 12,000 BTU/hr, and considering water's specific heat (1 BTU/lb-°F) and density (8.33 lb/gal).
Q3: What happens if flow rate is too low?
A: Low flow can cause laminar flow, reduced heat transfer efficiency, and potential chiller shutdown due to low flow protection.
Q4: What happens if flow rate is too high?
A: Excessive flow increases pump energy consumption, can cause erosion in pipes, and may reduce ΔT below design values.
Q5: Can this formula be used for other fluids?
A: This specific formula is designed for water. For other fluids, adjustments must be made for specific heat and density differences.