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Hahn S.,Johannes Kepler University | Waschl H.,Johannes Kepler University | Steinmaurer G.,Austria Solar Innovation Center | Del Re L.,Johannes Kepler University
2015 European Control Conference, ECC 2015

Since the last decade, hybrid electric vehicles have been and are introduced increasingly by automotive industry as they provide substantial improvements in fuel consumption. However, the optimal power distribution between the different energy sources in a HEV to achieve high efficiency is a non trivial problem. In a former work, an approximate solution to the generic optimization task by a two-stage approach based on linear programming and switching strategies was introduced, which is extended within this work. First, the opportunity to declutch and switch off the internal combustion engine is considered, which extends the linear program to a mixed integer linear program and leads to additional improvements in fuel consumption. The second extension introduces a receding horizon strategy that considers the current and a target state of charge of the battery at the end of the horizon during the top level optimization. Thus a complete knowledge of the driving cycle is not required but only a prediction for a shorter horizon. Furthermore, errors caused by model-plant mismatch and prediction can be compensated by the SOC feedback. Both extensions result in a minimum increase in computational effort and allow to formulate the optimization as mixed integer linear program and solve it by real-time capable solvers. As application example a parallel hybrid electric vehicle with realistic models of battery and powertrain and the opportunity to declutch the internal combustion engine is considered. The method and the proposed extensions are evaluated in simulation and experimental in which satisfactory results could be achieved in both cases. © 2015 EUCA. Source

Preisler A.,AIT Austrian Institute of Technology | Selke T.,AIT Austrian Institute of Technology | Focke H.,Austria Solar Innovation Center | Hartl N.,AEA Austrian Energy Agency | And 3 more authors.
Energy Procedia

Aim of the project was the development of a technology roadmap for solar thermal cooling in Austria involving the relevant market players. The main contents of the technology roadmap are the compilation of the initial position in terms of existing solar thermal cooling plants as well as relevant R&D results, identification of market potentials, technology development and the necessary measures for it. The technology developments are described in short term, medium term, and long term objectives as well as the connected market relevance for Austria and the economic development of this technology. Scenarios for a useful interaction with other sustainable thermal cooling technologies like cooling with district heating are analyzed to clarify the future position of solar thermal cooling in the Austrian energy supply. The market player of this technology reach from component manufactures (solar thermal collector, ab-/-adsorption chillers, ventilation systems, storages, control, etc.), business enterprises (hotels, breweries, laundries, supermarkets, etc.), building developers and consultancy engineers to research institutions, energy agencies and political decision makers. All of these groups were involved in the development of the technology roadmap by expert workshops and interviews. © 2012 The Authors. Source

Perez R.,University at Albany | Lorenz E.,University of Oldenburg | Pelland S.,Natural Resources Canada | Beauharnois M.,University at Albany | And 13 more authors.
Solar Energy

This article combines and discusses three independent validations of global horizontal irradiance (GHI) multi-day forecast models that were conducted in the US, Canada and Europe. All forecast models are based directly or indirectly on numerical weather prediction (NWP). Two models are common to the three validation efforts - the ECMWF global model and the GFS-driven WRF mesoscale model - and allow general observations: (1) the GFS-based WRF- model forecasts do not perform as well as global forecast-based approaches such as ECMWF and (2) the simple averaging of models' output tends to perform better than individual models. © 2013 Elsevier Ltd. Source

Reichl C.,AIT Austrian Institute of Technology | Lager D.,AIT Austrian Institute of Technology | Englmair G.,Austria Solar Innovation Center | Englmair G.,Technical University of Denmark | And 2 more authors.
Applied Thermal Engineering

To gain insight into the involved thermodynamic processes of open sorption systems and aid in layout and development of future designs, two different methodologies are presented for the numerical description of adsorption reactors using moving beds. In accordance to earlier laboratory measurements, the molecular sieve Köstrolith 4AK was selected as sorption material and thermo-physical measurements using thermogravimetry with simultaneous differential scanning calorimetry were presented to extract the necessary interpolation functions for modelling the kinetic behaviour. Using discrete particle models in a Navier Stokes CFD Solver and particle simulations based on LIGGGHTS, the mixing characteristics of the rotating drum setup were accessed. Adsorption based on the thermophysical measurements was implemented into the discrete particle model. Finally, a parametric study with different temperatures and water content in the inflow air was performed using a transient porous volume approach based on the adsorption implementation and different mixing algorithms. Whereas in a simple adsorption kinetic implementation, the volume averaged temperature of the reactor was already significantly reduced after 1.5 h, more realistic implementations showed a prolonged reaction time with a temperature peak at around 15 min. The temperature gap between the temperature of the particles and the usable temperature level for the energy extraction was reduced by introducing a mixing algorithm. In the simulations, zeolite temperature yields could be reached between 15 K and 28 K, corresponding to air temperatures above the material between 21 K and 33 K, which compared well to the experimental observations, where temperature shifts of the process air of up to 36 K were reported. The presented simulation methodology is able to identify partly unused areas in reactors. Numerical optimisation of the flow field and enhancing the particle mixing lead to improved reactor solutions. © 2016 Elsevier Ltd Source

Zettl B.,Austria Solar Innovation Center | Englmair G.,Austria Solar Innovation Center | Somitsch W.,IPUS Mineral and Umwelttechnologie
Energy Procedia

The potential of an open sorption storage process for space heating and hot water was evaluated using sorptive material namely zeolite 4A (low grade) and salt-based composite. Sorptive material beds of about 55 kg to 74 kg were able to generate an adsorption heat between 3 and 5 kWh and temperature shifts of the process air between 20 K and 25 K depending on the material type, the inlet air water content, and the state of dehydration of the storage materials. The evaluation of the composite material based on LiCl/MgSO4 and MgCl2/MgSO4 impregnated clinoptilolite (using max. desorption temperature of 110 °C) in a rotating heat drum showed that not agglomeration due to sticking of the grains happens, good controllability of the process was possible, and sufficient high temperature shifts for room heating applications were achieved. © 2015 The Authors. Source

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