Austrian researchers have developed an optimization framework that accounts for part-load efficiency when sizing and operating heat pumps, enabling more realistic system planning. A case study in Innsbruck found the approach could cut electricity consumption by 4.5% and annual costs by 2.9%, while relaxed formulations significantly reduced computation times.
An Austrian research group has developed an integrated optimization framework for heat pump investment planning that explicitly accounts for nonlinear part-load efficiency. The approach recognizes that heat pump efficiency varies with operating load, rather than remaining constant, depending on how much of the system’s total capacity is being used at a given time. This enables the model to more accurately represent real-world operating conditions.
“Heat pumps’ performance characteristics are inherently nonlinear, depending on factors such as minimum load constraints and part-load efficiency, particularly for inverter-driven systems,” explained the team. “While advanced optimization methods exist for operational scheduling, investment planning models typically neglect part-load behavior due to the computational challenges associated with solving nonlinear mixed-integer problems. Instead, simplified linear approximations are commonly employed.”
