A comparative analysis of dynamic evaporator models for organic Rankine cycle waste heat recovery systems

Abstract

As the Organic Rankine Cycle Waste Heat Recovery (ORC-WHR) gained research attention in recent years, the evaporator models are required in plant modeling and model-based controls. However, model comparison and selection works are lacking in ORC-WHR application. Different from the modeling work in literature, this paper aims to first time present a comparative study of three evaporator models for Organic Rankine Cycle Waste Heat Recovery (ORC-WHR) systems using the same set of identification parameters and experimental data. Finite volume model and moving boundary model are the most popular modeling methodologies in the field of ORC-WHR. Meanwhile, 0-D lumped models attract some research attention thanks to their low computational cost and least modeling effort. This paper first presents the three models, which are then validated with experiments data collected in a heavy-duty diesel engine ORC-WHR system. In the model comparison process, accuracy, computational cost and modeling effort are evaluated. All three models exhibit decent working fluid vapor temperature prediction accuracy with 6.6 K of mean error and 1.27% mean error percentage both in steady state and transient conditions. 0-D lumped model is found to be accurate enough for many application purposes, which is not found in literature. Based on the comparison results, model selection recommendation is given based on disparate application purposes and different phases of ORC-WHR system development.