Modeling and control for an integrated thermal hydronic system

This paper presents modeling and control methods for an integrated thermal hydronic system (ITHS) consisting of a solar thermal collector, a thermal storage unit and a thermal booster. Control inputs are: valves activation time, pitch angle, solar pump rate and compressor rate, measurements are: temperatures at critical points, and disturbances are: ambient air temperature, source water temperature and the position of the sun relative to the plane of the solar thermal collector. In this context, the problem of maintaining temperature within the given range of the thermal storage is considered. To address this problem, the model is developed based on lumped-parameter analysis. Using the model, three controllers are tested in simulations, i.e, the on-off controller, the PI controller and the scheduling controller. The modeling will be useful in developing optimal control for high efficiency ITHS.