1. Understand the Heat Balance
A Liquid Cooling Plate absorbs heat from a component and transfers it into circulating coolant. For single-phase liquid flow, the energy balance is:
Q: heat transferred to coolant, in watts.
ṁ: coolant mass flow rate, in kg/s.
Cp: specific heat capacity, in J/(kg·K).
ΔT: coolant outlet minus inlet temperature, in °C.
Rearranging gives ṁ = Q / (Cp × ΔT). For liquid water near room temperature, the approximate volume-flow shortcut is:
2. Worked Example: 1,000 W of Heat
Assume a 1,000 W heat load and an allowable water temperature rise of 5°C. The approximate water flow is 14.35 × 1 / 5 = 2.87 L/min. This is a preliminary estimate, not a guarantee of component temperature.
| Heat load | Coolant temperature rise | Estimated water flow |
|---|---|---|
| 500 W | 5°C | 1.44 L/min |
| 1,000 W | 5°C | 2.87 L/min |
| 1,500 W | 5°C | 4.31 L/min |
| 1,000 W | 10°C | 1.44 L/min |
3. Check Pressure Drop Before Selecting a Pump
A higher flow rate reduces coolant temperature rise but also increases hydraulic resistance. The operating pump flow is determined by the intersection of the pump curve and the complete loop resistance, including hoses, fittings, cold plate and heat exchanger.
Review tube inner diameter and total routing length.
Limit sharp bends and unnecessary connectors.
Check pressure drop at the actual coolant viscosity and temperature.
Allow for fouling, filters and other system-level restrictions.
4. Include the Full Thermal Resistance Path
Heat must travel through the component package, thermal interface material, base plate, tube wall and coolant-side convection layer. Poor tube contact or an uneven mounting surface can produce hot spots even when the flow calculation is correct.
For localized heat sources, a custom tube liquid cold plate can be routed beneath the areas that need the most cooling.
5. Engineering Validation Checklist
Define continuous and peak heat loads.
Specify coolant inlet temperature and allowable component temperature.
Calculate preliminary flow and pressure loss.
Verify mounting flatness and thermal interface thickness.
Test temperatures and pressure drop under worst-case conditions.
Conclusion
Use the heat-balance equation to estimate flow, then validate the complete Cold Plate Cooling System. A balanced design controls both thermal performance and pumping requirements.
Frequently Asked Questions
Will doubling flow cut component temperature in half?
No. Coolant temperature rise may decrease, but other thermal resistances remain.
Can I use the same equation for glycol?
Yes, with the actual fluid density and heat capacity.
What should I provide for a quotation?
Heat load, drawings, inlet temperature, available flow and pressure, and coolant specification.
Need a Custom Liquid Cold Plate?
KINGKA offers configurable tube-based liquid cold plates for industrial electronics. Share your drawings, heat load, coolant and installation requirements to discuss a suitable manufacturing solution.
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