CONTINUOUS_MODEL TD

  ABSTRACT
   "Ventilated hollow core = TermoDeck

    Treat the layer containing the ducts as a boundary layer
    between two homogeneous layers. The slab is assumed to have
    the same temperature all along the air path. The air temperature
    approaches this temperature exponentially as a parcel travels
    along the path.

    For a small area segment dArea we get:

      dTAir * M * cp = - h * dArea * (TAir - TSlab)

      TDiff = TAir - TSlab

      dTDiff     h * dArea
      ------ = - ---------
      TDiff      M * cp

    The temperature as function of path length becomes:

      TDiff(x) = c * exp (- h * Area(x) / (M * cp))

    Area = 0  at  TDiff = TIn - TSlab  gives:

      c = TIn - TSlab
   "

/* History:

*/

  EQUATIONS

/* Get cp of humid air */

   Cp := (1 - Hum) * CP_AIR + Hum * CP_VAP;

/* Calculate leaving air temp */

 FOR i=1, n
   TOutLoc[i] := TSlab[i] + (TIn - TSlab[i]) *
                 IF /*On*/ctrl[i] > 0 THEN
/*                 IF fraction[i]*M > 1E-6 THEN */
                   IF AirFract[i]*M > AlphaA[i] / (16.0 * Cp) THEN
                     exp (- AlphaA[i] / (AirFract[i]*M * Cp))
                   ELSE
/*                   0 */
                     exp(-16.0)
                   END_IF ;
                 ELSE
                   1
                 END_IF ;
 END_FOR;

/* Heat balance */

/*   Q := SUM i=1,nreal Q_tq[i] END_SUM;  */

/* Heat transfer to air stream */

 FOR i=1, n
   Q_tq[i] = AirFract[i]*ctrl[i]*M * Cp * (TOutLoc[i] - TIn);
 END_FOR;

/* Mean out temperature */

/* Q = M * Cp * (TOut - TIn); */
   Tout = SUM i=1,nreal AirFract[i] * TOutLoc[i] END_SUM + (1-fract_tot) * TIn;

/* Code for hardware lock */
/*   CALL VALRES(); */

/* Calculate mode of operation for next step */

/* FOR i=1, n */
/* On[i] := event(G1,ctrl[i]-0.5) + 0.5; */
/*   On[i] := ctrl[i];
 END_FOR; */

LINKS
/*   type        name         variables   */

 FOR i=1, n
   TQ           Term[i]       Tslab[i], POS_IN Q_tq[i]
 END_FOR;

 FOR i=1, n
   ControlLink  Control[i]    ctrl[i];
 END_FOR;

   UniAir       Inlet         P, POS_IN  M,  TIn, X, Hum ;
   UniAir       Outlet        P, POS_OUT M, TOut, X, Hum ;


VARIABLES
/*  type      name       role  def  min      max description    */

 Temp         TSlab[n]   IN    21   ABS_ZERO BIG "Temp of slab surface"
 Temp         TIn        IN    18   ABS_ZERO BIG "Inlet air temp"
 Temp         TOut       OUT   21   ABS_ZERO BIG "Mean Outlet air temp"
 Temp         TOutLoc[n] LOC   21   ABS_ZERO BIG "Outlet air temp"

/* HeatFlux     Q          LOC   20   -BIG     BIG "Flux to air from slab" */
 HeatFlux     Q_tq[n]    OUT    1   -BIG     BIG "Heat flux each _tq"

 Massflow     M          IN    0.024 0       BIG "Air massflow through duct"

 Pressure     P          IN    1375  -BIG    BIG "pressure in duct"
 Fraction_y   X          IN    594   0       BIG "pollutant fraction"
 HumRatio     Hum        IN    0.006 SMALL   BIG "moisture fraction"

 Control      ctrl[n]    IN    1     0       1   "control signal1 if TD on, 0 if TD off"

 HeatCapM     Cp         LOC   1017 1006     BIG "Cp of humid air"
/*
 Factor       G1         A_S   1     0       1   "old value of event function"
 Factor       On[n]      A_S   1     0       1   "1 if TD on, 0 if TD off"
*/


MODEL_PARAMETERS
/* type     name       role    def    min   max            description    */

   INT       n         SMP      1      1   BIGINT        "Number of thermodecks (incl. 'boundary')"            
   INT       nReal     SMP      1      1   BIGINT        "Number of 'real' thermodecks"            

PARAMETERS
/*  type     name        role  def  min      max description    */

 HeatCond    AlphaA[n]   S_P   50   SMALL    BIG "total transfer coeff"
/* Factor      fraction[n] S_P   50   SMALL    BIG "fraction massflow" */
 Factor      AirFract[n] S_P    1   SMALL    1   "Device's part of air flow"

 Factor      fract_tot   C_P    1   SMALL    1   "fraction massflow"

PARAMETER_PROCESSING

   fract_tot := SUM i=1,nreal AirFract[i] END_SUM;

END_MODEL