Card 9 - XCOND Conductances

This optional card specifies the parameters and options for defining conductances between elements.

Parameters: KODE, N1, T1, T2, T3, T4, T5, T6

KODE

KODE is the code XCOND (or 3)

N1

N1 is an element number, or a group name. If N1 is a group name, a conductance of value T2 is generated between all the elements of the N1 and the element(s) of T1.

T1

T1 is another element number, or a group name. If T1 is a group name, a conductance of value T2 is generated between the element(s) of the N1 and the elements of T1.

T2

T2 is the value of the conductance between elements N1 and T1.

T3

T3 is a code or a conductance number, or a table number.

T3 = 1WAYC

T3 = 1WAYC (or 2) creates a one-way conductive conductance between elements N1 and T1. N1 will be affected by T1, but T1 will not be affected by N1.

  • You can model fluid flow with one-way conductive conductances, where N1 is the downstream element, T1 is the upstream element, and T2 is the mass rate of flow times the fluid's specific heat (e.g., Btu/sec/F) flowing into element N1 from T1.
  • If a chain of 1-WAYC conductances is present, they should all be of the same magnitude, and start and end in a SINK element. If this rule is not followed, an energy imbalance will be shown in the verbose log file.

T3 = 1WAYR

T3 = 1WAYR (or 3) creates a one-way radiative conductance of value T2 = (area * emissivity * gray body view factor) between elements N1 and T1. N1 will be affected by T1, but T1 will not be affected by N1.

T3 = CNVSN

T3 = CNVSN (or 8) adds a linear conductance between elements N1 and T1.

  • The value of this conductance at run time is T2 times the value interpolated from table T4.
  • If T5 is neither zero nor blank, then it is interpreted to be the ID of a temperature vs time table.
  • This table defines the temperature history of a sink element whose element number is defined at run-time. The conductance is then created not between N1 and T1, but between the element N1 and this sink element.

T3 = CNVASN

T3 = CNVASN (or 9) adds a linear conductance between elements N1 and T1.

  • The value of this conductance at run time is area (N1) times T2 times the value interpolated from table T4.
  • If T5 is neither zero nor blank, then it is interpreted to be the ID of a temperature vs time table.
  • This table defines the temperature history of a sink element whose element number is defined at run-time. The conductance is then created not between N1 and T1, but between the element N1 and this sink element.

T3 = CNVSNR

T3 = CNVSNR (or 10) adds a linear conductance between the reverse side of element N1 and element T1.

  • The value of this conductance at run time is T2 times the value interpolated from table T4.
  • If T5 is neither zero nor blank, then it is interpreted to be the ID of a temperature vs time table.
  • This table defines the temperature history of a sink element whose element number is defined at run-time. The conductance is then created not between N1 and T1, but between the reverse side of element N1 and this sink element.

T3 = CNVASNR

T3 = CNVASNR (or 11) adds a linear conductance between the reverse side of element N1 and element T1.

  • The value of this conductance at run time is area (N1) times T2 times the value interpolated from table T4.
  • If T5 is neither zero nor blank, then it is interpreted to be the ID of a temperature vs time table.
  • This table defines the temperature history of a sink element whose element number is defined at run-time. The conductance is then created not between N1 and T1, but between the reverse side of element N1 and this sink element.

T3 = COND

T3 = COND (or 0) creates a linear conductive conductance of value T2 between elements N1 and T1.

T3 = CSERIES

T3 = CSERIES (or 5) adds a conductive conductance of value T2 in series with the linear conductances between elements N1 and T1, to reduce their value. This option can model contact conductances.

T3 = FOLLOWER

T3 = FOLLOWER (or 4) automatically makes T1 into a sink element with the temperature of N1. T1 should not be defined with a SINK Card.T2 is ignored.

T3 = FREE

T3 = FREE (or 7) creates a free convection conductance between elements N1 and T1. The heat flow through it is calculated with:

  • TN1 is the temperature of element N1
  • TT1 is the temperature of element T1
  • QN1T1 is the heat flow through the conductance by the Analyzer module.
  • T4 = blank defaults to T4 = 0.25.

T3 = RAD

T3 = RAD (or 1) creates a radiative conductance with T2 = (area * emissivity * gray body view factor) between elements N1 and T1.

T3 = RADSN2

T3 = RADSN2 (or 13) adds a radiative conductance between elements N1 and T1.

  • The value of this conductance at run time is area (N1) times emissivity(N1) times T2 times the value interpolated from table T4.
  • If T5 is neither zero nor blank, then it is interpreted to be the ID of a temperature vs time table.
  • This table defines the temperature history of a sink element whose element number is defined at run-time. The conductance is then created not between N1 and T1, but between the element N1 and this sink element.

T3 = RADSN3

T3 = RADSN3 (or 12) adds a radiative conductance between elements N1 and T1.

  • The value of this conductance at run time is area (N1) times T2 times the value interpolated from table T4.
  • If T5 is neither zero nor blank, then it is interpreted to be the ID of a temperature vs time table.
  • This table defines the temperature history of a sink element whose element number is defined at run-time. The conductance is then created not between N1 and T1, but between the element N1 and this sink element.

T3 = RADSNR2

T3 = RADSNR2 (or 15) adds a radiative conductance between the reverse side of element N1 and element T1.

  • The value of this conductance at run time is (area(N1)) * (emissivity of reverse side of N1) * T2 * the value interpolated from table T4.
  • If T5 is neither zero nor blank, then it is interpreted to be the ID of a temperature vs time table.
  • This table defines the temperature history of a sink element whose element number is defined at run-time. The conductance is then created not between N1 and T1, but between the reverse side of element N1 and this sink element.

T3 = RADSNR3

T3 = RADSNR3 (or 14) adds a radiative conductance between the reverse side of element N1 and element T1.

  • The value of this conductance at run time is area (N1) times T2 times the value interpolated from table T4.
  • If T5 is neither zero nor blank, then it is interpreted to be the ID of a temperature vs time table.
  • This table defines the temperature history of a sink element whose element number is defined at run-time. The conductance is then created not between N1 and T1, but between the reverse side of element N1 and this sink element.

T3 = RSERIES

T3 = RSERIES (or 6) adds a radiative conductance of T2 = (area * emissivity * gray body view factor) in series with the radiative conductances between elements N1 and T1.

  • T3 > 15 a conductive conductance of value T2 is created between elements N1 and T1 with the conductance number T3.
  • T3 < -15 a radiative conductance with (area * emissivity * gray body view factor) value = T2 is created between elements N1 and T1 with the conductance number abs (T3).
  • The T3 > 15 and T3 < 15 options pre-assign conductance numbers which are otherwise automatically assigned, so the conductances are referenced by user-written subroutines or INTERP Cards.

T4

T4 is an exponent associated with a free convection conductance, or blank, or a table number associated with CNV-type conductances.

T5

T5 is a table number associated with CNV-type conductances.

T6

T6 is the number of DESCRIP Card associated with the XCOND Card (optional).

Code example

XCOND 3 4 2 COND
$ CONDUCTIVE CONDUCTANCE OF VALUE 2.0 BETWEEN 3 AND 4
$
XCOND 5 6 7 RAD
$ RADIATIVE CONDUNCTANCE OF VALUE 7 BETWEEN 5 AND 6
$
XCOND 8 9 0 FOLLOWER
$ ELEMENT 9 FOLLOWS THE TEMPERATURE OF ELEMENT 8
$
XCOND 1 2 .5 FREE .33
$ FREE CONVECTION CONDUNCTANCE BETWEEN 1 AND 2