User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20121010 Thunderbird/16.0.1
Wang,
As it says in all of the"More" button comments for the Type9
"Interpolate or not" parameter and also in the mathematical
description of Type9, you should NOT use Type9 to interpolate solar
radiation data. Type9 interpolates linearly, which is a poor
assumption for the way in which solar radiation behaves over an
hour. Furthermore, the point of Type16 (solar radiation processor)
is to carry out an interpolation of solar radiation for timesteps
smaller than an hour.
I would highly recommend that you run a simulation with ONLY Type9
and Type65. Plot out all of the values that you are reading from
your file and make sure that they are all being treated correctly.
It can be somewhat tricky to set the "average or instantaneous
value" parameter and the "interpolate or not" parameters. Only after
you have verified the data is being read in properly should you then
adda Type16 to the project to make sure that solar radiation is
being processed correctly; again, there are some parameters that can
be challenging to set correctly.
Regards,
David
On 10/29/2012 05:17, 王洋 wrote:
dear all,
I would like to ask you a question about solar radiation. I met an
error as follows. I used Type 9e to import our own solar radiation
data whose unit is W/m2, meantime, I also used an Equation to
transfer its unit to kJ/hm2 (i.e. xx*3.6) and used ABS to ensure
its value as Positive connected with Type 16a (Radiation
processors). But it still appears the error as follows. Please
tell me how could I solve this problem? E.g. use which Type I
should use more easily and correctly and what are the detailed
processes to import our own solar radiation to connect with Type
56?
*** Fatal Error at time : 3820.800000
Generated by Unit : 56
Generated by Type : 56
Message : Negative value of solar radiation
for 5orientation encountered
I would like to ask you a question about solar radiation. I
met an error as follows. I used Type 9e to import our own
solar radiation data whose unit is W/m2, meantime, I also used
an Equation to transfer its unit to kJ/hm2 (i.e. xx*3.6) and
used ABS to ensure its value as Positive. But it still appears
the error as follows. Please tell me how could I solve this
problem? E.g. use which Type I should use more easily and what
are the detailed processes to import our own solar radiation
to connect with Type 56?
*** Fatal Error at time : 3820.800000
Generated by Unit : 56
Generated by Type : 56
Message : Negative value of solar radiation
for 5orientation encountered
When replying, please edit your Subject line so it is more
specific
than "Re: Contents of TRNSYS-users digest..."
Today's Topics:
1. Max. time points of Type 14 in TRNSYS 16 (??)
---------- 已转发邮件 ----------
From: 王洋 <wanghongyang1767@gmail.com>
To: trnsys-users@cae.wisc.edu
Cc:
Date: Fri, 26 Oct 2012 11:27:38 +0200
Subject: [TRNSYS-users] Max. time points of Type 14 in
TRNSYS 16
Dear all,
I'd like to ask you whether or not max. time points of
Type 14 is only 20 in TRNSYS 16?
If I need more than 20 points, how could I solve this
problem?
Vincent,
When you perform an energy balance on a tank, you
need to take into account its change in temperature
between the beginning and the end of the simulation
(output 7 of your Type4). If the tank ends up hotter
at the end of the simulation than it was at the
beginning, it has stored some energy. If it ends up
colder, then it has given up some energy. I would
imagine that with 10 nodes, there is some
stratification developing in the tank that is not
modeled when you have a fully mixed tank (1 node)
Best,
David
On 10/25/2012 09:40, PARTENAY Vincent wrote:
Dear all,
Typ4a
(Storage tank) allows to model a stratified
tank with several temperature nodes. The
problem I noticed is that the energy balance
of both sides on the tank can vary depending
on the chosen timestep :
In the
attached file, a simplified example, the
tank is coupled to an energy production and
energy consumption model (very simple in an
equation). Thermal losses of the tank is set
to zero.
When I
run a simulation with one node (1m height
for 0.5m3) for the tank and a timestep of
0.1hr, I get the same energy on both side
(see plotter “”Power&NRJ”, Esource =
2659kWh and Eload = 2666kWh), slight
difference maybe explained by initial
charging period to setpoint temperature.
When I
run it in the same conditions but with 10
nodes (each 0.1m), these two energy are
different ! While I still have 2666kWh for
Eload I have 3146kWh !
When I
run it again reducing the timestep from
0.1hr to 0.001 hr, still with 10 nodes, I
get 2666kWh, the energy balance is ok…
So, my
question is : is it necessary to check
before every bigger simulation (that can
include lots of tank models) the energy
balance of this model for one defined
timestep and boundary conditions to the
model or is there some rules to predefine
adapted discretisation for one given
timestep ?
Kind
regards,
Vincent
PARTENAY
Energies
Renouvelables - Département ESE
Centre
Scientifique et Technique du Bâtiment
290
Route des Lucioles BP 209 – F 06904 Sophia
Antipolis Cedex
---------- 已转发邮件 ----------
From: "Michaël Kummert" <michael.kummert@gmail.com>
To: <trnsys-users@cae.wisc.edu>
Cc:
Date: Thu, 25 Oct 2012 18:19:39 -0400
Subject: Re: [TRNSYS-users] Type energy balance
If
the energy (de)stored between the initial and
final state cannot explain the differences, I
think there is another possible cause: Type 4
can have quite large energy balance errors
when the nodes are “flushed out” during one
time step.
Here
is my understanding:
If
you have 10 nodes and a total volume of 500 L,
that means each node holds 50 L of water.
Using 0.1 h time steps you cannot have a
flowrate through the tank higher than 500 L/h,
otherwise you will replace the entire volume
of a node within a time step, and the
equations used by Type 4 are not valid
anymore. This would explain that it works
again when you reduce the timestep (with 0.001
h you would need a flowrate of 50000 L/h to
“flush” a node out).
To
my knowledge this problem is specific to Type
4, i.e. it does not affect the Storage tanks
in the TESS libraries (Type 534 etc.) – if you
have access to them that may be a more
practical solution than running 0.001 h
timesteps…
Vincent,
When you perform an energy balance on a tank,
you need to take into account its change in
temperature between the beginning and the end of
the simulation (output 7 of your Type4). If the
tank ends up hotter at the end of the simulation
than it was at the beginning, it has stored some
energy. If it ends up colder, then it has given
up some energy. I would imagine that with 10
nodes, there is some stratification developing
in the tank that is not modeled when you have a
fully mixed tank (1 node)
Best,
David
On 10/25/2012 09:40,
PARTENAY Vincent wrote:
Dear all,
Typ4a
(Storage tank) allows to model a stratified
tank with several temperature nodes. The
problem I noticed is that the energy balance
of both sides on the tank can vary depending
on the chosen timestep :
In the
attached file, a simplified example, the
tank is coupled to an energy production and
energy consumption model (very simple in an
equation). Thermal losses of the tank is set
to zero.
When I
run a simulation with one node (1m height
for 0.5m3) for the tank and a timestep of
0.1hr, I get the same energy on both side
(see plotter “”Power&NRJ”, Esource =
2659kWh and Eload = 2666kWh), slight
difference maybe explained by initial
charging period to setpoint temperature.
When I
run it in the same conditions but with 10
nodes (each 0.1m), these two energy are
different ! While I still have 2666kWh for
Eload I have 3146kWh !
When I run it again
reducing the timestep from 0.1hr to 0.001
hr, still with 10 nodes, I get 2666kWh, the
energy balance is ok…
So, my
question is : is it necessary to check
before every bigger simulation (that can
include lots of tank models) the energy
balance of this model for one defined
timestep and boundary conditions to the
model or is there some rules to predefine
adapted discretisation for one given
timestep ?
Kind
regards,
Vincent
PARTENAY
Energies
Renouvelables - Département ESE
Centre
Scientifique et Technique du Bâtiment
290
Route des Lucioles BP 209 – F 06904 Sophia
Antipolis Cedex