Efficient modeling of adsorption chillers: Avoiding discretization by operator splitting

International Journal of Refrigeration, vol. 139, pp. 180–191

Abstract

Reliable and computationally efficient models are crucial to improve the performance of adsorption chillers. However, modeling of adsorption chillers is challenging due to the intrinsic process dynamics. Currently, adsorption chillers are most often represented by 1-d, lumped-parameter models that use lumped models for all components but resolve the heat exchangers in one spatial dimension. Still, accurate simulations require fine discretization leading to poor computational efficiency. To increase computational efficiency, here, an alternative modeling approach is proposed that avoids discretization by applying operator splitting. The benefits of the proposed modeling approach are demonstrated in two real-world case studies. First, the resulting adsorption chiller model is calibrated and validated with experimental data of a lab-scale one bed adsorption chiller: The proposed model retains the accuracy of a state-of-the-art model while increasing computational efficiency by up to 70%. Second, the proposed model is applied to a commercial two-bed adsorption chiller with excellent accuracy. Finally, the validity of model is tested by varying the ratio between the overall heat transfer and the heat capacity rate of the fluid in the heat exchangers. The proposed model is shown to be well suited for the conditions present in most adsorption chillers.

Authors 3

1. Andrej Gibelhaus Aachen Institute of Technical Thermodynamics

   RWTH Aachen University

   Affiliation as printed

   Institute of Technical Thermodynamics, RWTH Aachen University, 52062 Aachen, Germany

2. Patrik Postweiler Aachen Institute of Technical Thermodynamics

   RWTH Aachen University

   Affiliation as printed

   Institute of Technical Thermodynamics, RWTH Aachen University, 52062 Aachen, Germany

3. André Bardow corresponding Aachen Institute of Technical Thermodynamics

   RWTH Aachen University · ETH Zurich · Forschungszentrum Jülich · Institute of Energy and Process Engineering

   Affiliation as printed

   Institute of Energy and Climate Research -Energy Systems Engineering (IEK-10), Jülich Research Center, 52425 Jülich, Germany

   Institute of Energy and Process Engineering, Energy and Process Systems Engineering, ETH Zurich, 8092 Zurich, Switzerland

   Institute of Technical Thermodynamics, RWTH Aachen University, 52062 Aachen, Germany