How many liters of water flow is required for 1 kW?

At ΔT = 20 K, approximately 43 L/h (0.043 m³/h) is required, while at ΔT = 10 K, approximately 86 L/h is required. Practical formula: flow rate (m³/h) ≈ power (kW) × 0.86/ΔT.

Why is the flow rate higher in the thermal oil circuit?

The specific heat of thermal oil (≈ 2.2–2.6 kJ/kg· K) is about half that of water (4.19) and its density is lower; the same power and ΔT require about 2 times the volumetric flow.

Thermal Power – Flow Rate Calculation (Q = m·c·ΔT) Hot Water, Glycol, Oil

The heat carried in hot water and thermal oil installations is determined by the flow rate and the supply–return temperature difference. This tool calculates the thermal power from the flow rate or the required flow rate from the thermal power . The density and specific heat of the water are taken at average temperature with IAPWS-IF97; typical values for glycol and thermal oil are filled in, you can also enter your own values.

Formula

Q = ṁ · c · ΔT ṁ = ρ · V̇

Example

For a thermal power of 1,000 kW, the flow required in a hot water circuit operating at 90/70 °C (ΔT = 20 K) is approximately 44.1 m³/h. A flow rate of 10 m³/h carries 227 kW of heat at 80/60 °C.

You can calculate the pipe diameter and pump power based on the selected flow rate. For thermal oil boilers, use the thermal oil option. You can consult Çiftel Kazan engineers for your boiler room and plumbing project.

Thermal Power and Flow Calculation (Q = m · c · ΔT)

Formula

Example

Frequently Asked Questions