Strange behavior of Type56 if NType as Output

Today I noticed that, in Type56 all outputs after NType 961 will not be saved into the B17 file, and the values are also incorrect. In the Type56 manual:

NTYPE 961 B4_QSOLAIR BAL 4: convective energy gain of zone due transmitted solar radiation through external windows which is transformed immediately into a con. heat flow to internal air [kJ/hr]

It is really strange. If I remove the NType 961 out of the outputs definition, the outputs list will work again.


wall transfer function coefficient error in TRNSYS

wall_transfer_function_coefficient_errorwall_transfer_function_coefficient_errorwall transfer function

This error shows up at the first place when I give the insulation layer a big thickness.

I wrote an E-Mail to transsolar support, and the trick is the Timebase setting in Output of Type 56, which is mentioned in the manual page 5-24.

more was discussed in the paper and presentation of Benoit Delcroix etc.

There are a few known workarounds when Type56 is not able to calculate transfer functions. I believe they have been discussed in the past but here are the ones I know:

– Sometimes the problem occurs for highly insulated walls that are not particularly thick or heavy. In that case replacing some insulation layers with mass-less layers can do the trick. Usually the thermal mass of the insulation layer can be neglected so this is my preferred approach.

– Split the wall in two (or more) parts. You should split the wall as you describe (e.g. half of the thickness in each wall for a uniform wall) but then add a fictitious zone between the two parts of the wall. You basically use that fictitious zone as an infinitely small and infinitely conductive air layer. You should set a very small volume and infinite convection coefficients in the fictitious zone. I think it is best to handle windows separately from the wall if you adopt that approach (windows do not need to be part of a wall in Type56).

– Increase the time base. This is obviously not a great idea if you also have much lighter walls in the building, but if you are simulating a castle with 3-m thick walls all over I guess that would be acceptable.

In any case I would setup a test model with standard walls that are OK, apply the workaround (e.g. add the fictitious zone) and check that the results are the same. Then you can replace the walls with the one that causes the problem.

I hope this helps,

Michaël Kummert
ESRU, University of Strathclyde

Trnsys Functions


How to create new component for TRNSYS 17

the basic is desribed in TRNSYS 17 Manual Volumen 1 Getting Started in 1.8. Creating a new component. The problem is, the tutorial was created for a long time, something changed since the Visual Studio .NET 2003 is not availble. When Visual Studio 2003 was used, the TRNSYS Studio compiles the DLL file directly and save them to the UserLib folder. Now, without Visual Studio 2003, you get a notification, and get two file exported. One .cpp file(C++ source file) and one .dsp(project description for Visual Studio). If you have new generation Visual Studio installed, then open the .dsp file with it, then a new .vcxproj file will be created as project desription file for the new Visual Studio – I use Visual Studio Express 2012. Then build the DLL is quite easy. If TRNSYS.h is not found, copy it form “Trnsys17\Compilers\Cpp-Mvs2003\Include”.

actually I wanna do it with MingW and Code::Blocks, somehow I cannot get it working, I will try later. The .dsp file has some configurations for the compiler and Code::Blocks cannot read it properly, I think. If someone knows how it works, please let me know.

The data structure of Type 56(Multi-zone) in TRNSYS

It looks like if I want to use the Heat Tansfer Coefficient based on the results from OpenFoam, I need modify the .inf file somehow. The Heat Transfer Coefficient depends on the Wall Surface Temperatue and the Air Temperature close to the wall. Usually, the convective heat transfer coefficient of wall is set per wall type either as userdefined or as internal calculation. During the internal calculation, the AirNode temperature is used, which will be replaced by OpenFoam in the Coupling. So, I think we should choose it as userdefined. Under userdefined dialog, we can see 3 options: Constant Value, Input, Schedule. Input should be the right choice, which means the convective heat transfer coefficient of each wall are defined as input for Type56. We can calculate them and save data in an external file. Because of the variation of the Air Temperature in CFD, the Heat Transfer Coefficient could also be variable. That means, for each surface of the geometry, a wall type should be defined according to the air temperature. CHTC

I searched whole day without success, the workflow is to use the heat flux value from OpenFoam for surface energy balance calculation instead of the process of internal calculation with airnode temperature. If Fluent is used, maybe Type 101 is just right for this, but OpenFoam is the tool available to me. I must find another solution to make this happen. I don’t really understand the setting of Wall Gain , is this just means Convective Heat Flux?