Cooling-System Coolant Flow for a Heat Load
The coolant flow a heat load needs at a given temperature rise.
Example
You enter
- Heat rejection to coolant (Btu/hr) 150000
- Coolant temperature rise (°F) 10
- Coolant water
You get
- Required coolant flow (gpm) 30
Checked against published worked examples from: Contracting Business (Rob Doc Falke).
Details, formula, and sources
Scopegpm = Q / (c x deltaT), c = 500 water / 427 glycol. 150,000 Btu/hr at a 10 F rise needs 30 GPM (water) or 35 GPM (50/50 glycol, ~17% more); a tighter 5 F rise doubles the flow to 60 GPM. A sizing aid; the equipment ratings and fluid properties govern.
Formula or tablegpm = Q / (c x deltaT); c = 500 water, 427 (50/50 glycol).
Source and editionThe sensible-heat coolant-flow relation gpm = Q / (c x deltaT), by name.
Free accessThe sensible-heat flow relation and the 500 (water) / 427 (glycol) constants are standard published heat-transfer results.
What governsEstimate. AHJ and licensed professional govern.
API field namesq_btuh, dt_f, coolant, gpm
- Sensible flow gpm = Q / (c x deltaT)heat-transfer first principles
- Fluid constant c = 500 water, ~427 for 50/50 glycolfluid properties
- Flow only does not size the pump head or heat exchangerscope of this tile