Description of device functions Proline Prowirl 73
148 Endress+Hauser
SELECT FLUID
(contd.)
Selected fluid: WATER DELTA HEAT
Prerequesite
This option requires Prowirl 73 to read in the temperature value of an external
temperature transmitter, which is HART-enabled and set to the burst mode, via the
HART input function. For a detailed connection diagram, see ä 30.
Applications:
A0001809
Calculated variables:
1. Calculation of the water mass flow and the heat withdrawn by a consumer load.
2. Calculation of the water mass flow and the heat added. The water thus has a cooling
effect.
Specify the mounting location of the Prowirl 73 in the INSTALLATION POINT function.
Formulae for calculation:
• Mass flow: m = q · (T73) (at the point of Prowirl 73)
• Delta heat: E = q · (T73) · (h (T73) – h (T2))
m = Mass flow
E = Delta heat
q = Volume flow (measured)
(T73) = Density*
h(T73) = Specific enthalpy at the point of the measuring device
h(T2) = Specific enthalpy at the point of T2
* from water and saturated steam data as per IAPWS-IF97 (ASME) for the measured
temperatures.
!
Note!
• If the algebraic sign of the temperature differential changes, error message #524 "SIGN
DELTA HEAT" is displayed. ä 67
• Prowirl 73 cannot take a change in the algebraic sign for the temperature differential
into account!
Function description, FLOW COMPUTER group
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