Dynamic modeling and experimental validation of household refrigerators/freezers equipped with phase change materials towards improved energy efficiency

Abstract

Phase change materials (PCMs) have significantly impacted domestic refrigeration systems' energy efficiency. By reducing the compressor On/Off frequency and decreasing electricity consumption, utilizing PCMs can substantially improve overall energy performance. This research aimed to evaluate a household freezer equipped with PCM for its thermal behavior and energy consumption. To achieve this, a dynamic model for household refrigerators and freezers with PCMs was developed, incorporating thermodynamics, heat transfers, mass and heat balances, and a control algorithm that specifically determined the PCM temperature and melted mass fraction over time. The proposed model introduces a new approach to the refrigeration cycle simulation by utilizing pressure-based hydraulic calculations, departing from the conventional method of relying only on thermodynamics. Furthermore, the model incorporates a dynamic PCM component into the refrigerator model. To validate the model, the simulator was compared to experimental data with and without PCM in the freezer cabinet; the results showed relative errors of 5.5% and 5.1% in power consumption, respectively. The developed model is fast enough to be used as an internal model for dynamic simulation and analysis, optimization, and control problems.