100/180 mm PAPERLESS GRAPHIC RECORDER: USER GUIDE
HA028910
Issue 13 Sep 16
User Guide
Page 122
4.3.11 FUNCTION (Cont.)
SATURATED STEAM HEAT FLOW
Note: The overall accuracy of a fl ow measurement installation depends on a number of factors
outside the control of the recorder manufacturer. For this reason, the recorder manufacturer takes
no responsibility for the accuracy of the results obtained using the mass fl ow equations imple-
mented in the maths pack.
The equation solved is:
where, QE
t
= Heat energy fl ow (in kJ/sec), at time ‘t’ (Note 1)
Flow
t
= Measured fl ow in m
3
/sec (Note 1)
V
LT
= Volume of liquid per kg of steam (m3/kg) at temperature T ˚C
∆V
T
= V
VT
- V
LT
, where V
VT
is the volume of vapour per kg of steam at temperature T ˚C
d = Dryness factor between 0 (no vapour) and 100 (no liquid)
h
LT
= Enthalpy of the liquid in kJ/kg at temperature T ˚C
∆h
T
= h
VT
- h
LT
, where h
VT
is the enthalpy of vapour in kJ/kg vapour at temperature T ˚C
V
LT
and ∆V
T
; h
LT
and ∆h
T
are available from published tables (note 2), but the recorder user needs only to
enter ‘values’ for measured fl ow and either the temperature or the pressure of the steam. These ‘values’
can be constants, input channels or maths channels. Figure 4.3.11j and accompanying parameter de-
scriptions give full details.
Figure 4.3.11j Typical Saturated Steam Heat Flow confi guration page
QE
t
!
Flow
t
V
LT
# &
V
T
d
100
. /
'(
)(
*(
*(
+(
,(
-(
-(
h
LT
# &
h
T
d
100
. /
.
/
PARAMETERS
Flow
Select ‘Constant’ or the number of the channel supplying the measured fl ow rate. If
‘Constant’ selected, a further ‘box’ allows the value for the constant to be entered.
Use
Allows the user to select Temperature (˚C) or Pressure (MPa) for the calculation.
Temperature
Appears only if Use = Temperature. Select ‘Constant’ or the number of the channel
supplying the steam temperature. If ‘Constant’ is selected, a further ‘box’ allows a
value for the constant to be entered.
Pressure (note 3)
Appears only if Use = Pressure. Select ‘Constant’ or the number of the channel sup-
plying the steam pressure. If ‘Constant’ is selected, a further ‘box’ allows a value for
the constant to be entered.
Dryness
Enter a value between 0 and 100 to represent the dryness of the steam. 0 = no va-
pour; 100 = no liquid.
Notes:
1 The units of kg/sec and m3/sec are used above for simplicity. In fact any time unit can be used.
For example if the measured fl ow is in m3/hour, then the Mass fl ow will be in kg/hour.
2. ASME Steam tables 1999, from IAPWF IF97.
3. See ‘Saturated Steam Mass Flow’ above for details of pressure unit conversion
Function
Flow
Use
Pressure
Dryness
Units
Maths Number
Value
Units
Apply Discard
%
Saturated Steam Heat Flow
Channel 1
10
Units
2) Math 2
987.6543
Pressure
Channel 2
