Power and energy

Heat-meter flow and return energy sanity check

Estimate thermal power from volume flow, fluid density, specific heat capacity and measured flow/return temperature difference.

Calculate

Measured circuit
m³/h
°C
°C
kg/m³
kJ/(kg·K)

Worked example

Thermal power, magnitude

 kW

Flow minus return temperature
20 K
Mass flow
 kg/s
Direction of heat transfer
flow hotter than return

Single-phase sensible-heat sanity check only. Approved heat-meter calculators use the specified sensor pair, fluid model and legal-metrology requirements.

Underlined figures are rounded. Select one to copy its full value.

Method and assumptions

Formula

thermal power = volume flow × density ÷ 3600 × specific heat × (flow temperature − return temperature)

With flow in m³/h, density in kg/m³ and specific heat in kJ/(kg·K), the result is kW.

Limits of this result

  • Use fluid properties at the relevant temperature and concentration; the defaults are only a water-like worked example.
  • A billing heat meter applies its approved calculator, sensor pair and fluid model; this result does not reproduce legal metrology.
  • Flow and temperatures must be time-aligned and represent the same hydraulic circuit.
  • The model is restricted to single-phase sensible heat; phase change, reaction heat and two-phase flow are outside it.

Technical sources

  1. Fundamentals Handbook: Thermodynamics, Heat Transfer, and Fluid Flow, Volume 2US Department of Energy · DOE-HDBK-1012/2-92, Rev. 0, equation 2-15
  2. SonoMeter 30 heat-meter energy verification guideDanfoss · VU.SH.I1.02, 2019-10

Put the value to work

Read the related engineering guidance, or carry this task into System Builder to identify the signal path and EpiSensor products.

Continue in System Builder Read: Wired M-Bus heat meter integration

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