Several
Flow Simulator elements use the heat addition
options described in this section. These elements include:
 Orifices and Generic Losses
 Discrete Loss
 HeaterCooler
 FI CdComp
 Fixed Flow Element
 Orifice Plates
 Valves
 Expansions and Contractions
The table below contains the complete list of the heat addition options and
numbers that are present in the *.
flo file. However, not all
elements include all options.
UI Name (*.flo Label) 
Description 
Heat Mode (HEAT_MODE) 
Mode of heat transfer to/from the fluid in the element.
 0: Adiabatic
 1: Heat Addition (Btu/s)
 2: Heat Addition per Mass Flow (Btu/lbm)
 3: Fixed Fluid Delta Total (degF)
 4: Fixed Fluid Total at exit (degF)
 5: Heat load as NTU
 6: Heat load as constant hA
 7: Adiabatic with JouleThomson effect
 8: Fixed Fluid Quality at Exit
 9: Heat from Compression

Heat Input (QIN) 
The value entered for QIN depends on the HEAT_MODE
selected.HEAT_MODE: QIN value
 0: QIN not used
 1: Heat Input (Btu/s)*
 2: Heat Input per Mass Flow (Btu/lbm)
 3: Element Delta Total (degF)
 4: Element Exit Total (degF)
 5: NTU (unitless)
 6: hA (BTU/hr/F)
 7: JouleThomson Coefficient (degF/psi)
 8: Element Exit Fluid Quality (01)
 9: Compression efficiency (%)
*In cases where multiple flow streams are
modeled by a single element (for example, NED and NLU not
equal to 1), set the value of QIN to model the heat flow
from only one of the restrictions. 
Fraction of QIN applied before restriction (QIN_RATIO) 
Fraction of the total heat to be added before the
restriction. (0 = None, 1 = All) 
Heat Addition Details
The element heat addition equations for each mode are detailed in this section. The
equations used also depend on the energy equations method. The energy equations can
be solved using
temperature*Cp or enthalpy.
Note: The enthalpybased equations only work when Coolprop is
used for the fluid properties.
 0. Adiabatic

$\u2206{T}_{t}=0or\u2206{H}_{t}=0$
 The total temperature change for an adiabatic element may not be 0 when
enthalpy is used for the energy equations. The JouleThomson (JT)
effect causes the total temperature to change due the pressure change
across the element. The JT effect is ignored when temperature is used
in the energy equations unless a JT coefficient is provided and
HEAT_MODE=7.
 1. Heat Addition

$\u2206{T}_{t}=\frac{{Q}_{in}}{\dot{m}{Cp}_{avg}}or\u2206{H}_{t}=\frac{{Q}_{in}}{\dot{m}}$

${Q}_{in}$
= Heat addition (user defined).
 2. Heat Addition per mass flow

$\u2206{T}_{t}=\frac{{Q}_{in}}{{Cp}_{avg}}or\u2206{H}_{t}={Q}_{in}$

${Q}_{in}$
= Heat addition per mass flow (user defined).
 3. Element Delta T

$\u2206{T}_{t}={Q}_{in}$
(
${Q}_{in}$
refers to the input variable name).

${Q}_{in}$
= Temperature change (user defined).
 The element exit total enthalpy is obtained by sending Coolprop the
element exit total temperature and static pressure.
 4. Element Exit Total Temperature

${T}_{t,exit}={Q}_{in}$
(
${Q}_{in}$
refers to the input variable name).

${Q}_{in}$
= Element exit total temperature (userdefined).
 The element exit total enthalpy is obtained by sending Coolprop the
element exit total temperature and static pressure.
 5. NTU

$\u2206{T}_{t}=({T}_{sink}{T}_{t,inlet})\left(1\mathrm{e}\mathrm{x}\mathrm{p}\left({Q}_{in}\right)\right)$
(
${Q}_{in}$
refers to the input variable name).

${Q}_{in}=NTU=\frac{hA}{\dot{m}{Cp}_{avg}}$
= Number of transfer units
 6. HTC*Area

$\u2206{T}_{t}=({T}_{sink}{T}_{t,inlet})\left(1\mathrm{e}\mathrm{x}\mathrm{p}\left(\frac{{Q}_{in}}{\dot{m}{Cp}_{avg}}\right)\right)$
(
${Q}_{in}$
refers to the input variable name).

${Q}_{in}=hA$
= HTC*Area
 7. Adiabatic with JouleThomson Effect
 If temperature used in energy equations and JT coefficient are
usersupplied:

$\u2206{T}_{t}={Q}_{in}*\left({P}_{s,exit}{P}_{s,inlet}\right)$
(
${Q}_{in}$
refers to the input variable name).

${Q}_{in}$
= JouleThomson coefficient (degF/psi).
 If Enthalpy is used in the energy equation:

$\u2206{H}_{t}=0$
and retrieve
${T}_{t,exit}$
from Coolprop using
${H}_{t,exit}$
and
${P}_{s,exit}$
.
 8. Fixed Fluid Quality at Exit
 This option only works if enthalpy is used for the energy equations and
Coolprop is used for the fluid properties. The
${T}_{t,exit}$
and
${H}_{t,exit}$
is retrieved from Coolprop using
${Quality}_{exit}$
and
${P}_{s,exit}$
.

${Q}_{in}$
= the quality at the element exit.
 9. Heat from Compression
 This option is only valid for the elements that can have a pressure
rise, like a fixed flow element or a Flow versus Source Pressure
element. You must verify that the pressures on both sides of the element
are accurate. If a fixed flow element is attached to a boundary, the
boundary's pressure does not have to be accurate unless this HEAT_MODE
is used.
 If Temperature is used in energy equations and the fluid is a
gas:
$$\u2206{T}_{t}=\frac{{T}_{t,inlet}}{{\eta}_{adiab}}*\left[{\left(\frac{{P}_{t,exit}}{{P}_{t,inlet}}\right)}^{\frac{\gamma 1}{\gamma}}1\right]$$
 If Temperature is used in energy equations and the fluid is a
liquid:

$\u2206{T}_{t}=\frac{{P}_{Hydraulic}}{\dot{m}{Cp}_{avg}}\left(\frac{1}{{\eta}_{adiab}}1\right)$

${P}_{Hydraulic}=\left({P}_{t,exit}{P}_{t,inlet}\right)*\frac{\dot{m}}{\rho}$
 If Enthalpy is used in the energy equation and there is any fluid
phase:

$\u2206{H}_{t}=\frac{\left({H}_{t,isentropic,exit}{H}_{t,inlet}\right)}{{\eta}_{adiab}}$
 Nomenclature:

$\u2206{T}_{t}={T}_{t,exit}{T}_{t,inlet}$
= the total temperature change.

$\u2206{H}_{t}={H}_{t,exit}{H}_{t,inlet}$
= the total enthalpy change.

$\dot{m}$
= mass flow rate.

${Cp}_{avg}$
= specific heat using an average temperature.

${\eta}_{adiab}={Q}_{in}/100=$
= compressor adiabatic efficiency.

$\rho $
= density
The QIN_Ratio
The heat can be applied before and/or after the restriction. If QIN_RATIO=0, all heat
is added after the restriction and the “upstream” temperature used in the flow rate
calculations is the temperature of the upstream chamber. The flow rate is only
adjusted if the fluid is not an incompressible liquid.
The equation used to adjust the flow rate is derived using the flow function (ff) and
does not change with a different temperature entering the
restriction.
$$ff=f{f}_{adjT}$$
$$\frac{\dot{m}\sqrt{{T}_{t,inlet}}}{{P}_{t,inlet}Area}=\frac{{\dot{m}}_{adjT}\sqrt{{T}_{t,inlet,adjT}}}{{P}_{t,inlet}Area}$$
$${\dot{m}}_{adjT}=\dot{m}\sqrt{\frac{{T}_{t,inlet}}{{T}_{t,inlet,adjT}}}$$
$${T}_{t,inlet,adjT}={T}_{t,inlet}+QI{N}_{RATIO}*\u2206{T}_{t}$$