scholarly journals Simulation of Performance of Thermal Energy Storage in a Solar Cooker

Author(s):  
Vikas Chourasia

Finite element analysis was used to simulate the performance of thermal energy storage in a solar cooker which was fabricated by our team. This cooker stores solar energy in materials like sand for future use. It is inexpensive to construct and can be widely used in villages and urban areas. The cooker energy storage unit consists of a cubical solid block which contains sand as a solar-energy storage unit, along with conducting aluminum sheets for uniform heat distribution throughout the block. The block is enclosed in a uniform layer of insulation, except the cavities on the top surface to allow heating of the sand and as well as near the cooking pot. This heated sand can be used at night to heat a cooking pot which is centrally located in the storage box. A paraboloidal concentrator focuses solar radiation through a secondary reflector onto the central zone of the storage block through the cavity in the insulation. The storage is charged for a set period of time and heat is subsequently discharged to a pot during the night time. The effects on cooker performance are compared for various numbers of plates in the storage block. The temperature attained at various stages is studied for various models. This can be used to cook food in a slow manner and can be kept heated until night.

Author(s):  
Mustafa Aktaş ◽  
Meltem Koşan ◽  
Erhan Arslan ◽  
Azim Doğuş Tuncer

The integrated usage of solar energy systems, heat pump applications, and thermal energy storage units is an effective way for heating systems due to their sustainability and stability in operations. In this study, a novel direct solar-assisted heat pump with thermal energy system has been designed which uses the solar collector as the evaporator of the heat pump. Besides, two-dimensional transient numeric analyses have been conducted for the thermal energy storage unit using the ANSYS Fluent 16.2 commercial software package. With this direct system, the heat required for heating systems is supplied from the condenser with the heat received from the solar collector of the working fluid. For an effective and high performance system, the solar collector is designed as a double-pass which provided superheating of the working fluid. It is aimed to store the surplus energy from the solar energy in the thermal energy storage unit and to operate the system continuously and efficiently in both sunny and overcast weather conditions. Furthermore, the system has been analyzed theoretically and the results show that coefficient of performance may improve. As a result, this newly designed system can be successfully applied for thermal applications.


2018 ◽  
Vol 1 (3) ◽  
pp. 34
Author(s):  
Luigi Mongibello ◽  
Nicola Bianco ◽  
Martina Caliano ◽  
Giorgio Graditi

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.


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