Thermohygrometric modeling and control for occupant comfort in buildings
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Authors
Okaeme, Charles C.
Issue Date
2018-05
Type
Electronic thesis
Thesis
Thesis
Language
ENG
Keywords
Mechanical engineering
Alternative Title
Abstract
We present a control strategy where the mass flow rates into each zone are the control inputs to the system, while the control objective is to drive the system outputs, i.e. temperature and humidity ratio, into a comfort zone set (a temperature and humidity ratio region defined on the psychometric chart) as recommended by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). We first show that the interconnected dynamic system is passive, therefore any passive controller is stabilizing and able to drive both temperature and humidity to steady states within the thermal comfort region. We then propose several passivity-based controllers to regulate the outputs within the comfort region. To illustrate the effectiveness of the proposed control strategy, simulation results from implementing the controller on the lumped model are then compared with CFD simulations of the testbed. The proposed controller design approach is also shown to be robust to model parametric uncertainty, with results of the CFD simulations verifying this attribute. The control structure is finally improved through inclusion of a learned feed-forward input. Since buildings are generally subjected to repeated disturbances, such as weather conditions and specific occupancy schedules, the control performance may be enhanced through iterative learning control for increased disturbance rejection and output regulation. The feed-forward control preserves the passivity configuration of the overall system and ensures thermohygrometric convergence within the comfort set.
Description
May 2018
School of Engineering
School of Engineering
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY