TRNSYS Forum - Recent Posts

How to Create a Valid Performance Data File for Type 107 at Low Hot-Water Temperatures?

MPM — Tue, 01 Sep 2026 08:00:10 +0000

Hello everyone,

I am currently developing a TRNSYS model of a solar-assisted cooling system that integrates a single-effect absorption chiller, solar thermal collectors.

For the absorption chiller, I am using Type 107. However, I have encountered an important issue regarding the default performance data file.

The default Type 107 data file in my TRNSYS installation uses the following inlet hot-water temperatures:

108.89, 111.67, 113.89, 115.00, and 116.11 °C.

My system, however, is designed to operate a low-temperature single-effect absorption chiller with a hot-water inlet temperature around 85–95 °C.

Therefore, using the default Type 107 performance file would place the chiller outside the temperature range of the original performance map.

I understand that simply replacing the hot-water temperature values in the default data file, for example changing them to 75, 80, 85, 90, and 95 °C, while keeping the original capacity and energy-input fractions unchanged, would not represent a physically valid chiller model.

I also found the following TESS/Yazaki data file:

Yazaki20-50ton(OneStage)S3.dat

which provides the relationship between inlet hot-water temperature and fraction of nominal cooling capacity:

76.67 °C → 0.00
79.44 °C → 0.25
82.22 °C → 0.47
85.00 °C → 0.63
87.78 °C → 0.82
90.56 °C → 0.97
93.33 °C → 1.06
96.11 °C → 1.13
98.89 °C → 1.22

This information is very useful for defining the effect of hot-water inlet temperature on cooling capacity. However, it appears to be insufficient for constructing the complete Type 107 performance data file.

As I understand it, the Type 107 data file also accounts for:

fraction of design load,
chilled-water setpoint,
entering cooling-water temperature,
inlet hot-water temperature,

and requires both:

capacity fraction, and
design energy input fraction.

The main difficulty is that publicly available manufacturer catalogues for low-temperature single-effect absorption chillers usually provide only nominal operating conditions or a limited number of correction curves. Complete multidimensional performance data are rarely available.

My required nominal cooling capacity is approximately 113 kW (about 32 TR), and the intended hot-water operating range is approximately 80–95 °C.

I would therefore appreciate guidance from experienced TRNSYS users or developers on the following questions:

What is the recommended method for creating a new Type 107 performance data file for a low-temperature hot-water-driven absorption chiller?
Are there existing Type 107 or TESS data files for single-effect absorption chillers operating in approximately the 75–95 °C range?
Does anyone have the corresponding Yazaki S1 and S2 data files associated with Yazaki20-50ton(OneStage)S3.dat?
If only the hot-water capacity correction curve is available from the manufacturer, is it acceptable to combine this manufacturer-specific relationship with normalized part-load, chilled-water-temperature, and cooling-water-temperature relationships from another validated absorption-chiller dataset?
How should the Design Energy Input Fraction be determined when the manufacturer provides cooling-capacity correction factors but does not provide detailed heat-input or COP data for all operating conditions?
Would another TRNSYS/TESS absorption-chiller component be more appropriate than Type 107 for modeling a solar-driven single-effect chiller operating around 85–95 °C?
If manufacturer selection software can provide several off-design operating points, would it be acceptable to use those data to construct the multidimensional performance map required by Type 107?

My main objective is to avoid arbitrary extrapolation and to build a performance file that is physically meaningful and defensible for academic research.

Any recommendations, example data files, documentation, or previous experience with this issue would be greatly appreciated.

Thank you very much for your help.

Pleiades Modeleur -> TRNBuild : A simpler way to create TRNSYS building models

Mohamed TABERNOUST — Tue, 11 Aug 2026 12:16:53 +0000

Hello everyone 🙂 ,

I would like to share a tool that may be interesting for TRNSYS users who need to create detailed multi-zone building models.

IZUBA, the French distributor and support team for TRNSYS, has developed a gateway between Pleiades Modeleur and TRNBuild.

This can be particularly useful for users working with multi-zone buildings. In Pleiades Modeleur, zones can be created with a single click, and the contacts between adjacent zones are automatically detected. There is no need to manually define the connections between zones, which can significantly simplify the modeling process and reduce the risk of errors 😎 .

Another advantage is the easy definition of solar shading and surrounding obstacles. The building environment can be imported directly into Pleiades Modeleur, making it much easier to model neighboring buildings that affect solar gains . And also the possibility to define and export different schedules, such as occupancy, ventilation, heating and cooling.

Documentation and examples:

TRNSYS FAQ:
https://pleiades-doc.com/v4/fr/index.php/FAQ_TrnSys

Pleiades modeler → TRNBuild documentation:
https://pleiades-doc.com/v4/fr/index.php/Exporter_vers_Editeur_(Modeleur)?toc-id=404#Export_TRNSYS_.28Version_Alpha.29

Pleiades-modeler-to-TRNBUILD.png

Can TRNSYS be repurposed for predicting the energy impact of speculative megastructures (e.g., Dyson spheres) on Earth’s climate? Кто где смотрит русские сериалы онлайн в хорошем качестве?

Rosserial_Laf — Tue, 04 Aug 2026 14:41:54 +0000

I’m curious whether the modular nature of TRNSYS allows us to model absurdly large, non‑physical constructs and assess their hypothetical thermal footprints. Would such a “science‑fiction” exercise be a legitimate use of the software, or does it cross the line into misuse? Совсем недавно российские сериалы существенно выросли по уровню: сюжетные линии стали более продуманными, актёрская игра стала сильнее и речь персонажей стала естественнее. Чтобы не пропустить лучшие российские сериалы и легко найти, что посмотреть сегодня вечером, загляните на наш сайт с русскими сериалами — у нас собраны достойные новинки и любимые хиты новые российские сериалы 2026

Open position as a professor for simulation of thermal systems

Klaus Lambers — Tue, 28 Jul 2026 16:01:42 +0000

Dear friends of the TRNSYS community,

If, in addition to your passion for thermal simulation, you also have a enthusiasm for teaching (though in German) and hold a PhD, then a position as a professor at the Technical University of Applied Sciences Cologne (TH Köln) with a focus on thermal simulation might be of interest to you.

https://www.linkedin.com/feed/update/urn:li:share:7480219408578207744/

https://karriere.th-koeln.de/job/view/1566/professur-fuer-thermische-energ

If you are interested, don't hesitate, to contact me.

Controlling type 941

HumbertoSantos — Sun, 12 Jul 2026 13:15:48 +0000

Dear all,

I have carefully searched for more instructions on how to set up the control signals for the heat pump Type 525. However, I have not found any relevant information. If you have set up the control for this type of heat pump, could you please provide me with some guidance? Alternatively, if there is already a post about this, please let me know, as I was unable to find it.

In my case, I am trying to use the PV surplus instead of an electrical battery. I am using a heat pump to charge a PCM tank. Since Type 941 has a fixed-speed compressor, it will only run when the PV surplus is much higher than its rated power.

I have tried splitting my Type 941 heat pump into two units, and I was able to improve the results by operating a smaller-capacity unit when the PV surplus is lower. This made me think that using the variable-speed compressor Type 525 could be a better solution for maximizing heat storage based on the available PV surplus, as I could better adjust the heat pump's operation according to the available surplus.

The annual data I have consist of the building's heating and cooling loads in kW, and I am using Type 682 to simulate the building. Therefore, I am not using Type 56.

If there is any other information you need in order to help me, please feel free to ask.

Thank you.

Humberto

RE: Heat pump simulation with type 682

HumbertoSantos — Sun, 12 Jul 2026 12:48:17 +0000

@danieljack Hi Daniel, thank you. I still have some problems with writing logic control equations that sometimes make the system not to converge, but with time and looking at it closely it is possible to solve it. Can I ask what kind of project are you doing in trnsys? Thanks

Answer to: Heat pump simulation with type 682

DanielJack — Sat, 20 Jun 2026 10:54:41 +0000

Thanks for the detailed update, Humberto. Glad to hear you were able to improve the model and resolve the convergence issue. Sounds like you’re on the right track. Good luck with the further improvements!

TRNBuild - Wall thickness limitation

Doris Buck — Thu, 18 Jun 2026 07:13:41 +0000

Hello Bartolome,

unfortunately I couln't reply earlier. But I still want to provide a link to an article that might be helpful:

https://doi.org/10.1016/j.egypro.2017.09.371

The authors analyzed the results of TRNSYS and EnergyPlus simulating thick walls up tp 1.9 m. The walls thicker than 1 m were split into two layers. Maybe this helps.

Regards, Doris

Answer to: Error message in Type1287

DavidBradley — Wed, 27 May 2026 21:48:36 +0000

@antonio

Did you play around at all with the parameters that control the number of nodes in the collector and the number of subtimesteps that the model uses? If not I would start by increasing those values.

If that doesn't solve the problem then my guess as to the problem is that at times when there is little solar radiation the model is trying to slow the flow down to a very small rate so that it can achieve the desired outlet temperature and at those flow rates the temperature changes from node to node might be getting unrealistically large.

In reality pumps can only turn down to perhaps 10-20% of their rated flow. What I usually do in the case of a collector that is trying to maintain an outlet temperature is to send the collector's "desired" flow rate to a pump that has a minimum turndown imposed on it. The flow rate that the collector actually gets may be higher than it wanted and the collector may not achieve the desired temperature during low solar radiation periods but that is a more realistic situation anyway. Sometimes I use two instances of the collector model; one instance is calculating the desired flow rate and then the other instance is just getting the actual flow rate from a pump model.

~david

Answer to: Run time error '339': Component 'COMDLG32.OCX' or one of its dependencies not correctly registered" a file is missing or invalid.

RoseSears — Wed, 27 May 2026 19:46:47 +0000

@saeidbina

The primary cause of this problem is if you've installed some other software that uses a similar command prompt file, the TESS libraries can get confused and try to reference that other location. Try uninstalling the TESS libraries from the TESSLibs_Uninstall.exe in your TRNSYS directory and reinstalling them. Also make sure that you install the same version of the TESS libraries as you did for TRNSYS (64-bit or 32-bit). If you are in TRNSYS18, I recommend the 64-bit version. With a new PC it may be possible that it no longer supports the 32-bit version.

I hope this helps!