Flexim FLUXUS F502TE - Thermal Energy Rate Measurement; Calculation of the Thermal Energy Rate

19 Thermal energy rate measurement
FLUXUS F502TE 19.1 Calculation of the thermal energy rate
137
UMFLUXUS_F502TEV1-5EN, 2020-05-29
19 Thermal energy rate measurement
The measurement system consists of the transmitter, the ultrasonic transducers, the temperature probes and the pipe on
which the measurement is carried out.
One temperature probe is fixed on the supply line, the other one on the return line.
The transducers can be fixed on the supply or return line.
For the corresponding transmitter settings see section 19.2.
A temperature correction (offset) can be set for each temperature input (see section 19.2.5).
In the SuperUser mode, it is possible to define a temperature-based cut-off flow of the thermal energy rate (see
section 17.7).
The thermal energy is the totalizer of the thermal energy rate.
19.1 Calculation of the thermal energy rate
The thermal energy rate is calculated with the following formula:
Φ = k
i
· · (T
V
- T
R
)
where
The thermal coefficient k
i
is calculated from several thermal energy rate coefficients for the specific enthalpy and the
density of the fluid. The thermal coefficients of some fluids are stored in the internal database of the transmitter.
Fig. 19.1: Thermal energy rate measurement with flow measurement
1 – transducers
2 – supply line
3 – return line
4 – temperature probe on supply line (for supply temperature T
V
)
5 – temperature probe on return line (for return temperature T
R
)
6 – transmitter (heating/cooling application)
Tab. 19.1: Possible measurement arrangements
heating application T
V
> T
R
transducers on supply line
transducers on return line
cooling application T
V
< T
R
transducers on supply line
transducers on return line
Φ – thermal energy rate
k
i
– thermal coefficient
– volumetric flow rate
T
V
– supply temperature
T
R
– return temperature
1
54
6
2 3
V
·
V
·