Modeling and analysis of an integrated solid state elastocaloric heat pumping system

- An approach is developed to evaluate integrated thermoelastic heat pumping systems.
- A model is created for dynamic simulation of discretized thermal processes/control.
- Time coordination of loops and components is essential for effective cooling.
- Cost effective system design/operation should be derived from integrated analysis.
- Performance optimization is demonstrated for a 1.2-kW air-air cooling system.

Elastocaloric cooling (ECC) is considered as one of the candidates to replace vapor compression cycles, which use refrigerants with global warming potential (GWP) as working fluids. In order to properly understand the ECC system performance, it is critical to conduct analysis at the integrated system level. Also, due to the cyclic operation of an ECC system, dynamic modeling becomes necessary to capture the associated transients. In this study, for air conditioning applications, a unique air-to-air ECC dynamic system model has been developed to simultaneously simulate the elastocaloric effect of NiTi, heat transfer, and water transport in the system. Key parameters have been identified from sensitivity analysis of various options as well as the dynamic coupling among components. A systematic methodology has been further developed to identify practical solutions of the integrated ECC system, which provides a basis for comparison against other existing cooling technologies. Performance of an integrated ECC system with 1.2 kW net cooling capacity has been optimized using the NSGA-II method for maximum coefficient of performance (COP) within operational constraints. It has been demonstrated that effective system design and energy-efficient operation can only be achieved from optimization of the entire integrated system instead of a component or subsystem.