Integration of Modelica models into an existing simulation software using FMI for Co-Simulation

Abstract The Functional Mock-up Interface (FMI) opens new opportunities for the development and extension of existing non-Modelica simulation programs with Modelica models. For the developer this is a productive way to design and validate new complex simulation models with multi-domain modeling languages such as Modelica. With the standardized Functional Mock-up Interface (FMI) and the Functional Mockup Unit (FMU) export it is possible to execute these models within other software tools, including information exchange during the simulation. However, there are some design requirements in Modelica, which have to be taken into account. In this paper, models for different HVAC (Heating, Ventilation and Air Conditioning) equipment configurations are integrated into existing software using the FMI. An interface extension plug-in is developed to pick a specific FMU and execute it alongside the existing simulation algorithm. Two different coupling algorithms were investigated: the iterative and the cosimulation approach. Some issues and practical hints for a successful coupling and simulation are presented

A holistic modeling framework for estimating the influence of climate change on indoor air quality

The IPCC 2021 report predicts rising global temperatures and more frequent extreme weather events in the future, which will have different effects on the regional climate and concentrations of ambient air pollutants. Consequently, changes in heat and mass transfer between the inside and outside of buildings will also have an increasing impact on indoor air quality. It is therefore surprising that indoor spaces and occupant well-being still play a subordinate role in the studies of climate change. To increase awareness for this topic, the Indoor Air Quality Climate Change (IAQCC) model system was developed, which allows short and long-term predictions of the indoor climate with respect to outdoor conditions. The IAQCC is a holistic model that combines different scenarios in the form of submodels: building physics, indoor emissions, chemical-physical reaction and transformation, mold growth, and indoor exposure. IAQCC allows simulation of indoor gas and particle concentrations with outdoor influences, indoor materials and activity emissions, particle deposition and coagulation, gas reactions, and SVOC partitioning. These key processes are fundamentally linked to temperature and relative humidity. With the aid of the building physics model, the indoor temperature and humidity, and pollutant transport in building zones can be simulated. The exposure model refers to the calculated concentrations and provides evaluations of indoor thermal comfort and exposure to gaseous, particulate, and microbial pollutants.Peer reviewe

Selection of potential iron oxide nanoparticles for breast cancer treatment based on in vitro cytotoxicity and cellular uptake

Superparamagnetic iron oxide nanoparticles (SPIONs) are promising tools for the treatment of different diseases. Their magnetic properties enable therapies involving magnetic drug targeting (MDT), hyperthermia or imaging. Depending on the intended treatment, specific characteristics of SPIONs are required. While particles used for imaging should circulate for extended periods of time in the vascular system, SPIONs intended for MDT or hyperthermia should be accumulated in the target area to come into close proximity of, or to be incorporated into, specific tumor cells. In this study, we determined the impact of several accurately characterized SPION types varying in size, zeta potential and surface coating on various human breast cancer cell lines and endothelial cells to identify the most suitable particle for future breast cancer therapy. We analyzed cellular SPION uptake, magnetic properties, cell proliferation and toxicity using atomic emission spectroscopy, magnetic susceptometry, flow cytometry and microscopy. The results demonstrated that treatment with dextran-coated SPIONs (SPIONDex) and lauric acid-coated SPIONs (SPIONLA) with an additional protein corona formed by human serum albumin (SPIONLA-HSA) resulted in very moderate particle uptake and low cytotoxicity, whereas SPIONLA had in part much stronger effects on cellular uptake and cellular toxicity. In summary, our data show significant dose-dependent and particle type-related response differences between various breast cancer and endothelial cells, indicating the utility of these particle types for distinct medical applications

Implementation and validation of a long-wave heat exchange model

The hygrothermal whole-building simulation software WUFI® Plus was extended with a new model: the calculation of longwave radiative heat exchange between surfaces inside a zone. This allows a more detailed calculation of the interior radiative and surface temperatures, which also results in a better simulation of indoor climate conditions. The model also takes into account the optical properties of indoor surfaces, such as low-e coatings. Further benefits are a more comprehensive comfort assessment, for example, for asymmetric radiant temperature. Radiant temperatures can also be calculated for every position inside a zone. The model uses Gebhart factors for the calculations of long-wave heat exchange between surfaces inside a zone. These factors describe the fraction of emitted energy from one surface that is absorbed at another. They are determined from view factors, which only describe geometrical relationships between surfaces. WUFI® Plus uses a numerical triangulation method to calculate the view factors. As the Gebhart factors also consider optical properties of surfaces, all possible radiation paths, including multiple and own reflections, are taken into account for the calculations. Single parts of the calculation process are successfully validated with analytical solutions: the view factor calculation of a nontrivial room geometry and the long-wave heat exchange between two parallel plates show only minimal deviations from the analytical results. The German standard DIN EN 13791 provides tests for the validation of interior long-wave heat exchange. The model was successfully validated with them. In an exemplary application case, simulations with the new model are used as a preliminary study to determine the required accuracy and positioning of measurement equipment of a future test room. The simulated surface temperatures were successfully used as a plausibility control. The measurements will later be used as an experimental validation test for the new model

Anbindung von detaillierter Anlagentechnik an hygrothermische Gebäudesimulation

The multi-domain modelling language Modelica offers a magnificent method to develop, simulate and validate of different simulation models. Some graphical user interfaces support this design process even more and reduce the amount of work. Besides, the software development fort the end user is done with traditional programming languages as for the development for the hygrothermal building simulation software WUFI® Plus. Specialized and efficient solution techniques compute the coupled heat- and moisture transfer through the building components and furthermore by coupling those components the indoor climate. This paper describes the existing building simulation with ideal plant equipment and the implementation of the dynamic simulation of the plant equipment designed in Modelica. Those detailed Plant equipment models are coupled via the Functional Mock-up Interface (FMI) to the existing software. Necessary improvements are shown. A developed configuration tool enhances the coupling of many and different models without any further source code adaptations. Finally, a short example simulation is done to present some of the new features with this coupled simulation

Monthly balance based method versus transient whole building energy simulation for passive house design

For the design of the so called passive houses a monthly balance based method, is used. This paper compares the balance based method of the Passive House Planning Package (PHPP) with the results of an easy to use whole building energy simulation software based on a simplified black-box model. The different calculation methods for all heat flows influencing the energy performance are compared. Shortcomings and advantages of the different methods are discussed. It is shown that both methods can produce similar results when transient effects are neglected. It can be concluded, that the time demand to set-up a complete calculation in each of the tools is approximately the same. The amount of information and possible improvement strategies regarding energy demand and comfort that can be achieved are higher with the transient simulation

Kopplung von dynamischer Wärmebrückenberechnung mit hygrothermischer Gebäudesimulation

With increasing requirements on the thermal envelope of buildings dynamic building simulation is used more and more often for the design. Contrary to balance methods thermal bridges are often not accounted for in dynamic simulation. Especially the combination of a hygrothermal building simulation with the simulation of thermal bridges would allow assessing the dynamic influence of thermal bridges on the building energy demand, but also allow analyzing a possible risk for mould growth. This article presents the simulation methods for hygrothermal whole building simulation and thermal bridge simulation as well as their coupling. After validation of the thermal bridge module, which ensures a standard-conform implementation, an exemplary application case for the new simulation software is shown. Mould growth is sometimes found in the non-insulated and before damage free apartment, in cases where one of two side-by-side apartments is retrofitted with interior insulation. It is shown, how the temperature distribution in the exterior wall is changed due to the partial interior insulation measure. The influence of room temperature, moisture production, room ventilation and insulation thickness on the relative humidity on the coldest spot in the corner is analyzed. The partial retrofit causes higher and sometimes critical moisture conditions on the connection between exterior wall and party wall. In summary a hygrothermal whole building simulation software with coupled three dimensional dynamic thermal bridge simulation is presented. The thermal bridge module is successfully validated and the combined software applied to a practical case