Abstract
Thermal energy storage systems can be determinant for an effective use of solar energy, as they allow to decouple the thermal energy production by the solar source from thermal loads, and thus allowing solar energy to be exploited also during nighttime and cloudy periods. The current study deals with the modelling and simulation of a cooling thermal energy storage unit consisting of an aluminum container partially filled with a phase change material (PCM). Two unsteady models are implemented and discussed, namely a conduction-based model and a conduction-convection-based one. The equations systems relative to both the models are solved by means of the Comsol Multiphysics finite element solver, and results are presented in terms of temporal variation of temperature in different points inside the PCM, of the volume average liquid fraction, and of the cooling energy stored and released through the aluminum container external surface during the charge and discharge, respectively. Moreover, the numerical results obtained by the implementation of the above different models are compared with experimental ones obtained with a climatic chamber. The comparison between numerical and experimental results indicate that, for the considered cooling energy storage unit, free convection plays a crucial role in the heat transfer inside the liquid PCM and cannot be neglected.
Highlights
A properly designed thermal energy storage system can improve the exploitation and profitability of many renewable and conventional energy sources
Many works have addressed the use of phase change material (PCM) for storing thermal energy from the solar source for various applications, ranging from solar water heating to solar cooling by absorption or adsorption refrigeration systems [1,2,3,4,5,6]
This is essentially because the conduction-based model does not permit to simulate the mixing of liquid PCM inside the aluminum container in the initial part of the cooling energy charge
Summary
A properly designed thermal energy storage system can improve the exploitation and profitability of many renewable and conventional energy sources. Aljehani et al [12] simulated a phase change composite consisting of a paraffin wax and expanded graphite for cold thermal energy storage in air conditioning applications. They performed an experimental validation of numerical results. Various models have been developed for the numerical simulation of PCM-based thermal energy storage systems, most of which have been reported in reviews [15,16,17]. Lamberg et al [21] implemented both the effective heat capacity method and the enthalpy method to simulate the melting and solidification processes of a PCM They compared the numerical results, which were obtained using the FEMLAB solver, with experimental ones.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
