Optimal Dynamic Operation of Adsorption-based Energy Systems Driven by Fluctuating Renewable Energy

Abstract

Adsorption-based energy systems can provide environmentally friendly heating and cooling energy as they can be driven by low-grade heat, such as solar or waste heat. However, solar and often also waste heat are fluctuating over time. Thus, an optimal operation policy has to be identified to run adsorption-based energy systems efficiently. This work therefore presents a method to determine the optimal control for dynamic adsorption-based energy systems. To determine the optimal control, a two-step approach is used: First, the original non-linear dynamic model is approximated by a set of linear ordinary differential equations connected by Heaviside functions. In a second step, an optimal control problem is formulated and optimized for a set of control variables using a gradient method. The derived model predictive control is tested for a non-linear adsorption chiller model. The MPC shows good performance for both efficiency and specific power as objective functions.