Abstract

This work presents detailed 3D modelling and simulation of the mechanical effects induced by lightning strikes in protected carbon fibre-reinforced polymer laminates. Firstly, physically based models that represent the mechanical overpressure that results from a lightning strike are revisited. In particular, this paper compares the implementation of an analytical strong shock wave approximation with the solutions obtained from computational fluid dynamics (CFD), considering different equations of state, to represent the supersonic expansion of the hot plasma channel when simulating the mechanical damage induced by lightning strikes. The assessment of the pressure profiles, the numerical predictions of the displacement and velocity fields and the analysis of the predicted damage maps show that, for two lightning protection layers, the effects of the supersonic plasma expansion loads obtained from the strong shock wave approximation compare reasonably well with those obtained from CFD, independently of the equation of state solved numerically. Subsequently, the predictions of the 3D modelling strategy of the mechanical response of composite laminates subjected to lightning strike employing the strong shock wave approximation are compared with mechanical deformation measurements obtained from lab-scale lightning test results. Accurate deflection and out-of-plane velocity fields are predicted, validating the 3D modelling strategy. Moreover, the predicted damage maps correlate well with the (bulk) damage identified by C-scan (considering only the damaged area below the second ply).

This paper investigates the practical implementation of models in the energy management of buildings for complex user behavior and the use of multiple heating technologies, focusing on the development of an accurate yet efficient model. The study is exemplified by the new Institute for Hydrogen and Energy Technology building at Hof University of Applied Sciences, designed as a research platform for innovative energy solutions. We address the integration of shading strategies and the subsequent model order reduction necessary for effective Model Predictive Control application. The research involves creating a simplified resistance-capacitance model of the building's thermal zones, including its heating systems and a dual façade with solar thermal collectors. This simplified model, generated using the BRCM Toolbox and validated against a detailed EnergyPlus model, accounts for dynamic discrepancies, particularly during periods of high solar radiation. Optimization techniques are applied to the simplified model across different seasons, revealing that season-specific optimizations are more effective for long-term simulations, while a combined optimization approach is suitable for short-term and year-round MPC applications. The results underscore the potential of advanced MPC strategies to enhance energy efficiency and sustainability in complex building systems with multiple renewable energy sources.

Mid-sized thermal energy storage (TES) systems, especially in the distributed sector, have received little attention for public buildings. Validation of such systems, especially for the use of multiple renewables with different operating modes using CFD simulations, is still pending. The objective of this study is to validate a CFD model for the operation of complex and mid-sized TES systems for simultaneous charging and discharging cycles to enable investigations on optimized operating modes, geometric optimizations, and predictive charging and discharging scenarios. For this purpose, the 60 m3 local heating storage of Großbardorf, Germany, was used to obtain real-time operating conditions and in-situ temperature distribution data. Charging and discharging cycles as well as combined scenarios were calculated and compared with the experimentally determined dynamics of the thermocline. Simulations were performed using the open-source tool OpenFOAM® with the single-phase transient solver buoyantPimpleFoam in laminar and turbulent modes, including ambient heat losses. Good agreement was found between simulated and experimental data, especially in the regions of layer transitions with a RMSE of 1.2 ℃ or less over the entire observation period. It is shown how the validation allows further improvements and optimizations of TES with greater confidence. In particular, for research on the efficient use of multiple, fluctuating renewable energies and the increase of self-sufficiency in the decentralized sector, a demand-optimized charging and discharging layout is presented for a mid-sized TES to be installed at the new Institute for Hydrogen and Energy Technology (iwe) at Hof University of Applied Sciences. By conducting research in facilities such as the iwe, this approach will not only create opportunities for the future deployment of renewable energy storage and related systems, but also highlight the importance of decarbonization in the decentralized sector.

IFAT München 2024

Solar World Congress 2023, Neu Delhi, Indien 

5. Praxistagung "Wasserstoff aus Biomasse und Biogas", Krefeld

Statuskonferenz Bioenergie, Leipzig

H2.INSIGHTS#6 des Zentrum Wasserstoff

Statuskonferenz Bioenergie, Leipzig

Sommerakademie; Hof 

Symposium der BMWK-Energieforschungsnetzwerke, Berlin

31. C.A.R.M.E.N. Symposium, Würzburg