Dear TRNSYS users,
I have a problem, when I try to use the storage
array in TRNSYS using the specific funcions (setstoragesize
, getstoragevars, setstoragevars). I created a new type and
use the type65d to see the results while the simulation is
running. The main problem is that the type on itself works
properly without any error, but as soon as I link their
outputs to the input of the online plotter, I obtained a
“invalid floating point operation” error at the initial
timestep, forcing the simulation to stop. Also if the two
types are not linked, it give me the error. Only if I set
the number of right and left axis variables both to 0, the
simulation runs properly.
This error has been encountered by others too
(e.g.
http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/2013-April/011470.html
,
http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/2012-February/009376.html
,
http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/2010-July/006481.html
).
TRNSYS version: 17 OS: Windows 7 64bit, the
type is compiled as .cpp with Microsoft Visual Studio
Express 2012 and linked as .dll
TRNSYS.h has been modified to include the
storage functions:
extern
"C" __declspec(dllimport) double _cdecl
SETSTORAGESIZE(int* NSTORE,int info[]);
extern
"C" __declspec(dllimport) double _cdecl
SETSTORAGEVARS(double* STORE_IN,int* NSTORE,int info[]);
extern
"C" __declspec(dllimport) double _cdecl
GETSTORAGEVARS(double* STORE_OUT,int* NSTORE,int info[]);
#define
SetStorageSize
SETSTORAGESIZE
#define
SetStorageVars
SETSTORAGEVARS
#define
GetStorageVars
GETSTORAGEVARS
Below there is a description of my type:
In order to make it simple I created a
simplified version that takes as input one temperature, as
parameters the number of nodes of the tube and the shell and
the initial temperaure, and produces 4 outputs, outlet tube
temperture and 3 temperatures in the shell. The role of the
type is to increase the temperatures of the tube and the
shell by 1, every timestep. The heat exchanger is modelled
as vary layers (like a storage tank), set by the heat
transferfluid (htf) nodes.
The purpose of the type is to simulate a shell
and tube heat exchanger, thus I need to store the “old”
values at the very end of the timestep into the storage
arrays, and retrieve them every call of the type. In order
to simplify the problem let’s assume a single tube in a
shell.
In order to understand the general idea, I
should say that I need to use the dynamic allocation in
order to create the arrays based on the number of nodes,
defined by the user, in the parameters. Once the user sets
as parameters the nodes along the tubes direction
(nodes_htf) and along the radial direction in the shell
(nodes_shell), a vector for the tube temperatures and a
matrix (nodes_htf x nodes_shell) for the shell temperatures
should be created.
I implemented the following steps, compiling
each time and check the simulation run in trnsys:
1.
I set up the dimension of the storage array in
the section “very first call of the simulation” (it works
perfectly but of course the type does do anything)
int store_size =
nodes_htf*(nodes_shell+1); //set the storage size to store
Nhtf + Nhtf * Nshell temperatures
SetStorageSize(&store_size,info);
2.
I set up the initial values of the outputs and
store them in the section “do all the initial timestep
manipulations” (it works perfectly but of course the type
does do anything)
int store_size =
nodes_htf*(nodes_shell+1);
stored = new
double[store_size];
for(int
i=0;i<store_size;i++)
{
stored[i]=Tini;
}
SetStorageVars(stored,&store_size,info);
delete[] stored;
3.
I retrieve the storage values on before make
chenge to them, section “Retrieve the values in the storage
array for this iteration” (if I use the type alonein the
deck it works perfectly, but as soon as I introduce the
type65 it gives the
floating point error!!!).
int store_size =
nodes_htf*(nodes_shell+1);
stored = new double[store_size];
GetStorageVars(stored,&store_size,info);
delete[] stored;
The files are attached:
-
Type205 cpp
-
Project6: deck with type alone
-
Project7: deck with type205 + type65
Thank you for the help. In you need to
understand the purpose, you can read the next steps here
below (which are commented in the type205 code):
4.
I save the storage values in the “old” arrays
for the htf and the shell
Thtf_old = new double [nodes_htf];
Tshell_old = new double
*[nodes_htf];
for (int
i=0;i<nodes_htf;i++){Tshell_old[i]=new
double[nodes_shell];}
//assign the storage values to the
old array
for (int i=0;i<nodes_htf;i++)
{
Thtf_old[i] =
stored[i*(nodes_shell+1)];// the values are supposed to be
stored per layer so the first value is for the HTF and the
others are for the shell
for (int
j=1;j<nodes_shell+1;j++)
{
Tshell_old[i][j-1] = stored[i*(nodes_shell+1)+j];
}
}
delete[] stored;
5.
I create the new values arrays at the first
iteration for the current timestep (info[6] = 0, otherwise
if every I create them every call I allocate too much
memory), and calculate the new values from the old ones and
set the outputs
if (info[6] == 0)
{
Thtf = new double[nodes_htf];
Tshell = new double *[nodes_htf];
for (int i=0;i<nodes_htf;i++){Tshell[i] = new
double[nodes_shell];}
}
for (int i=0;i<nodes_htf;i++)
{
Thtf[i] = Thtf_old[i] + 1.0;
for (int j=0;j<nodes_shell;j++)
{
Tshell[i][j] = Tshell_old[i][j] + 1.0;
}
}
delete[] Thtf_old;
for (int i=0;i<nodes_htf;i++){delete[] Tshell_old[i];}
delete[] Tshell_old;
//Set the outputs
Tout = Thtf[nodes_htf-1];
Tshell_top = Tshell[0][nodes_shell-1];
Tshell_mid =
Tshell[int(floor(nodes_htf/2.0))-1][nodes_shell-1];
Tshell_bot = Tshell[nodes_htf-1][nodes_shell-1];
6.
I save the new values in the trnsys storage
array in the after iteration section in oder to make them
available for the next time step iterations. I should save
in that section otherwise every call the type would retrieve
the wrong values.
int store_size =
nodes_htf*(nodes_shell+1);
stored = new
double[store_size];
for (int i = 0; i <
nodes_htf; i++)
{
stored[i*(nodes_shell+1)] = Thtf[i];
for (int
j=1;j<nodes_shell+1;j++)
{
stored[i*(nodes_shell+1)+j] = Tshell[i][j-1];
}
}
delete[] Thtf;
for(int
i=0;i<nodes_htf;i++){delete[] Tshell[i];}
delete[] Tshell;
SetStorageVars(stored,&store_size,info);
delete[] stored;
Thank you very much for the help!
J
Sergio Pintaldi