Parametric studies and structural optimization of a PCM tank integrated with CO2 heat pumps

Abstract

Current studies mainly focus on parametric studies and structural optimization of PCM tank in component level, and parametric studies and structural optimization of PCM tank integrated with heat sources in system level are seldomly performed. Therefore, this study presents methods for parametric studies and structural optimization of PCM tank integrated with heat sources. Charging time, stored energy, total electricity use, and system coefficient of performance are considered as performance indicators, and water fraction, tube length, and outer diameter are considered as decision variables in the method for parametric studies. Central composite design method is applied to develop surrogate models, and genetic algorithm is applied to maximize system coefficient of performance or minimize total electricity use in the method for structural optimization. A PCM tank integrated with both water-source and air-source CO₂ heat pumps is considered as a case study for illustrating the methodology. It could be found that when the water fraction increased from 0.4 to 0.8, the system coefficient of performance for the system with water-source and air-source CO₂ heat pumps was increased by 12.2 % and 6.6 %, respectively. Thus, this study provides a guideline for parametric studies and structural optimization of PCM tank integrated with heat sources.