5.4.5. Table Look-Up for Steam Generators or Intermediate Heat Exchangers

Table look-ups for steam generators or intermediate heat exchangers are used when the behavior of these components is known from other sources or when the details of the temperature distributions within the components are not important for the case at hand. The user specifies normalized temperature drops vs. time or outlet temperatures vs. time, as well as elevation of the thermal center vs. time. These boundary conditions can be specified as tables vs. time or as function blocks.

The thermal center of the steam generator or intermediate heat exchanger is the point above which the circulating fluid is assumed to have the density corresponding to the inlet temperature and below which it is assumed to have the density corresponding to the outlet temperature.

In the case where the user specifies normalized temperature drops vs. time, the outlet temperature of the steam generator or intermediate heat exchanger is calculated from the inlet temperature by

(5.4-102)\[T_{\text{out}} \left( t \right) = T_{\text{in}} \left( t \right) + f \left( t \right) \left\lbrack T_{\text{out}} \left( t = 0 \right) - T_{\text{in}}\left( t = 0 \right) \right\rbrack\]

where \(f \left( t \right)\) is obtained by linear interpolation from the user-supplied table of temperature drops or by evaluation of the user-supplied function block which defines temperature drop. Also

(5.4-103)\[f \left( t = 0 \right) = 1.0\]

In the case where the user specifies outlet temperatures vs. time, the outlet temperature of the steam generator or intermediate heat exchanger is obtained by linear interpolation from the user- supplied table of outlet temperatures or by evaluation of the user-supplied function block which defines outlet temperature.

The gravity head is calculated from

(5.4-104)\[\Delta p_{\text{gr}} \left( t \right) = \rho_{\text{in}} \left( t \right) g\left\lbrack z_{\text{c}} \left( t \right) - z_{\text{in}} \right\rbrack + \rho_{\text{out}} \left( t \right) g \left\lbrack z_{\text{out}} - z_{\text{c}} \left( t \right) \right\rbrack\]

where

\(\rho_{\text{in}} \left( t \right), \rho_{\text{out}} \left( t \right)\) = the densities of the inlet and outlet fluids at the inlet and outlet temperatures

\(z_{\text{c}} \left( t \right)\) = the user-supplied elevation of the thermal center as a function of time

\(z_{\text{in}}\), \(z_{\text{out}}\) = the inlet and outlet elevations

\(g\) = the acceleration of gravity

5.4.5.1. Table HX Input Description

For model independent HX input refer to Section 5.4.2.7.

Table 5.4.11 Input in INPMR4 (Block 3) for all table look-up IHX/SG models

Variable	Description
IHXCLC	Table number or function block ID (ITAB) for HX IIHX
ISGCLC	Table number or function block ID (ITAB) for SG ISGN
iHXZID	Table number or function block ID (ITAB) defining height of thermal center for HX IIHX
iSGZID	Table number or function block ID (ITAB) defining height of thermal center for SG ISGN

If a function block ID is provided for an input above, then the corresponding input listed in the tables below is not used.

Table 5.4.12 Input in PMR4IN (Block 18) for all table look-up IHX models

Variable	Range	Description
TMPMTB	>=0.0	Times for DTMPTB and ZCENTR.
ZCENTR	-	Height of thermal center for an IHX or steam generator.

Table 5.4.13 Input in PMR4IN (Block 18) for a normalized temperature drop table look-up IHX model

Variable	Range	Description
DTMPTB	-	Normalized temperature drop for an IHX or steam generator.

Table 5.4.14 Input in PMR4IN (Block 18) for an outlet temperature table look-up IHX model

Variable	Range	Description
DTMPTB(1,ITAB)	> 1.0	Steady State outlet temperature for the primary element in an IHX or steam generator.
DTMPTB(2:,ITAB)	> 0.0	Outlet temperature for the primary element in an IHX or steam generator.

Table 5.4.15 Input in PMR4IN (Block 18) for a normalized heat rejection table look-up IHX model

Variable	Range	Description
DTMPTB(1,ITAB)	= 1.0	Steady State normalized heat rejection for the primary element in an IHX or steam generator.
DTMPTB(2:,ITAB)	-	Nomalized heat rejection for the primary element in an IHX or steam generator.
DTSIHX	>0.0	The inital temperature difference between the inlet and out of a heat exchanger.
VSIHX1	>0.0	The volume of the inlet region of a heat exchanger.
VSIHX2	>0.0	The volume of the outlet region of a heat exchanger.