Panagiota Karava

Agent-based system identification for control-oriented building models

The paper presents a general agent-based system identification framework as potential solution for data-driven models of building systems that can be developed and integrated with improved efficiency, flexibility and scalability, compared to centralized approaches. The proposed method introduces building sub-system agents, which are optimized independently, by solving locally a maximum likelihood estimation problem. Several models are considered for the sub-system agents and a systematic selection approach is established considering the root mean square error, the parameter sensitivity to output trajectory and the parameter correlation. The final model is integrated from selected models for each agent. Two different approaches are developed for the integration; the negotiated-shared parameter model, which is a distributed method, and the free-shared parameter model based on a decentralized method. The results from a case-study for a high performance building indicate that the model prediction accuracy of the new approach is fairly good for implementation in predictive control.

Investigation of the Turbulent Flow Behaviour in a Transpired Air Collector

There is an increasing interest in developing renewable energy systems to address the increasing global energy demand and fight climate change. One emerging technology is the transpired air collector, which is a unique type of corrugated and perforated sheet metal installed in front of a building to absorb incident sunlight to preheat the building air intake. As the airflow behaviour in the channel influences the air heat gain, it is important to understand the fluid dynamics within the transpired air collector to maximize its efficiency. A full scale experimental setup using a commercial transpired air collector was built in a laboratory environment. Particle Image Velocimetry (PIV) was used to measure two-dimensional velocity fields at different air flow rates and at different locations inside the channel. PIV data were used to compute various turbulent characteristics of the air flow. It was found that the mean velocity peaks tended towards the flat construction wall side. The profiles of the Reynolds stress indicated a significant momentum transfer from the corrugation wall by the turbulent velocity field towards the bulk flow. Results demonstrate that the turbulence produced by the corrugation waveform dominates the entire channel.Copyright