TY - GEN
T1 - An Integrated Control System for Heating and Indoor Climate Applications
AU - Tahersima, Fatemeh
PY - 2012
Y1 - 2012
N2 - Low temperature hydronic heating and cooling systems connected to renewable energy sources have gained more attention in the recent decades. This is due to the growing public awareness of the adverse environmental impacts of energy generation using fossil fuel. Radiant hydronic sub-floor heating pipes and radiator panels are two examples of such systems that have reputation of improving the quality of indoor thermal comfort compared to forced-air heating or cooling units. Specifically, a radiant water-based sub-floor heating system is usually combined with low temperature heat sources, among which geothermal heat pump, solar driven heat pumps and the other types are categorizedas renewable or renewable energy sources. In the present study, we investigated modeling and control of hydronic heat emitters integrated with a ground-source heat pump. Optimization of the system performance in terms of energy efficiency, associated energy cost and occupants’ thermal comfort is the main objective to be fulfilled via design of an integrated controller. We also proposed control strategies to manage energy consumption of the building to turn domestic heat demands into a flexible load in the smart electricity grid.We developed a simulation infrastructure for computer-based testing of the developed control methodologies. As the basis for components modeling, dynamical modeling of hydronic radiators controlled by thermostatic radiator valves is studied thoroughly. We have shown via analytical studies that a simply designed gain scheduling controller will overcome the well know instability problem of radiators which usually occurs in low heat demand conditions. We dealt with the problem as a dilemma between stability and performance. Since, controller parameters can be chosen such that the radiator works stable in the entire operation region, as a result the performance will become deterioratedduring the cold season. To overcome the dilemma, an adaptive controller is designed analytically which satisfies both performance and stability at all operating points. The studied radiator model is further adapted to the modeling of the sub-floor heating system.In order to minimize the electric power consumption of the integrated heating system, a novel hypothesis is proposed and further investigated via experimental and simulation studies. The idea is to minimize the forward temperature of hot water in order to maximize the heat pump’s efficiency and by this means reduce the power consumption of the heat pump. The hypothesis is that such an optimal point coincides with saturation of at least one of the subsystems control valves. The idea is implemented experimentally using simple PI and on/off controllers on a real test setup i.e. a multiple room detached housein Copenhagen; the hypothesis is further investigated by designing a hierarchical control structure which uses model predictive controller (MPC) at the top level orchestrating single control loops at the lower level of control hierarchy. MPC is specifically chosen in order to embed measured exogenous disturbances e.g. comfort profile, weather forecast and electricity price signals. Incorporation of the latter knowledge in the decision making enables the domestic energy consumer to act as a flexible load in the smart electrical gridto regain balance.
AB - Low temperature hydronic heating and cooling systems connected to renewable energy sources have gained more attention in the recent decades. This is due to the growing public awareness of the adverse environmental impacts of energy generation using fossil fuel. Radiant hydronic sub-floor heating pipes and radiator panels are two examples of such systems that have reputation of improving the quality of indoor thermal comfort compared to forced-air heating or cooling units. Specifically, a radiant water-based sub-floor heating system is usually combined with low temperature heat sources, among which geothermal heat pump, solar driven heat pumps and the other types are categorizedas renewable or renewable energy sources. In the present study, we investigated modeling and control of hydronic heat emitters integrated with a ground-source heat pump. Optimization of the system performance in terms of energy efficiency, associated energy cost and occupants’ thermal comfort is the main objective to be fulfilled via design of an integrated controller. We also proposed control strategies to manage energy consumption of the building to turn domestic heat demands into a flexible load in the smart electricity grid.We developed a simulation infrastructure for computer-based testing of the developed control methodologies. As the basis for components modeling, dynamical modeling of hydronic radiators controlled by thermostatic radiator valves is studied thoroughly. We have shown via analytical studies that a simply designed gain scheduling controller will overcome the well know instability problem of radiators which usually occurs in low heat demand conditions. We dealt with the problem as a dilemma between stability and performance. Since, controller parameters can be chosen such that the radiator works stable in the entire operation region, as a result the performance will become deterioratedduring the cold season. To overcome the dilemma, an adaptive controller is designed analytically which satisfies both performance and stability at all operating points. The studied radiator model is further adapted to the modeling of the sub-floor heating system.In order to minimize the electric power consumption of the integrated heating system, a novel hypothesis is proposed and further investigated via experimental and simulation studies. The idea is to minimize the forward temperature of hot water in order to maximize the heat pump’s efficiency and by this means reduce the power consumption of the heat pump. The hypothesis is that such an optimal point coincides with saturation of at least one of the subsystems control valves. The idea is implemented experimentally using simple PI and on/off controllers on a real test setup i.e. a multiple room detached housein Copenhagen; the hypothesis is further investigated by designing a hierarchical control structure which uses model predictive controller (MPC) at the top level orchestrating single control loops at the lower level of control hierarchy. MPC is specifically chosen in order to embed measured exogenous disturbances e.g. comfort profile, weather forecast and electricity price signals. Incorporation of the latter knowledge in the decision making enables the domestic energy consumer to act as a flexible load in the smart electrical gridto regain balance.
M3 - PhD thesis
SN - 978-87-92328-96-0
ER -