CH-24-C026 - Model-Based Hot Water Draw Estimation in Heat Pump Water Heaters

This study introduces a Luenberger observer design for estimating water flow rate in heat pump water heaters (HPWHs) using tank temperature measurements, eliminating the need for flow meters. Initially, a dynamic thermal model of the HPWH tank is presented. Subsequently, the details of the observer design for estimating water flow rate in HPWHs are outlined. Simulation and experimental results demonstrate the observer's capability in accurately detecting water flow rate. Additionally, a correlation between improved model accuracy and enhanced observer performance is established. The envisioned utility of these flow rate estimates is to serve as input data for a data-driven hot water draw forecaster. These forecasts can be integrated into a model predictive control for HPWHs to ensure user comfort.