Edible Oils as Practical Phase Change Materials for Thermal Energy Storage

Kahwaji, Samer; White, Mary Anne

doi:10.3390/app9081627

Cited by 56 publications

(21 citation statements)

References 46 publications

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“…However, due to the small thickness, the liquid layer was hardly studied, given the difficulties to observe directly or even to measure such a region. In the growing scenario of PCM literature [5][6][7][138][139][140], further investigation efforts have to be made to clarify the physical phenomena that occur in the liquid layer, as well as to enforce and validate the existing theoretical equations.…”

Section: Discussionmentioning

confidence: 99%

Fixed Grid Numerical Models for Solidification and Melting of Phase Change Materials (PCMs)

et al. 2019

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Phase change materials (PCMs) are classified according to their phase change process, temperature, and composition. The utilization of PCMs lies mainly in the field of solar energy and building applications as well as in industrial processes. The main advantage of such materials is the use of latent heat, which allows the storage of a large amount of thermal energy with small temperature variation, improving the energy efficiency of the system. The study of PCMs using computational fluid dynamics (CFD) is widespread and has been documented in several papers, following the tendency that CFD nowadays tends to become increasingly widespread. Numerical studies of solidification and melting processes use a combination of formulations to describe the physical phenomena related to such processes, these being mainly the latent heat and the velocity transition between the liquid and the solid phases. The methods used to describe the latent heat are divided into three main groups: source term methods (E-STM), enthalpy methods (E-EM), and temperature-transforming models (E-TTM). The description of the velocity transition is, in turn, divided into three main groups: switch-off methods (SOM), source term methods (STM), and variable viscosity methods (VVM). Since a full numerical model uses a combination of at least one of the methods for each phenomenon, several combinations are possible. The main objective of the present paper was to review the numerical approaches used to describe solidification and melting processes in fixed grid models. In the first part of the present review, we focus on the PCM classification and applications, as well as analyze the main features of solidification and melting processes in different container shapes and boundary conditions. Regarding numerical models adopted in phase-change processes, the review is focused on the fixed grid methods used to describe both latent heat and velocity transition between the phases. Additionally, we discuss the most common simplifications and boundary conditions used when studying solidification and melting processes, as well as the impact of such simplifications on computational cost. Afterwards, we compare the combinations of formulations used in numerical studies of solidification and melting processes, concluding that “enthalpy–porosity” is the most widespread numerical model used in PCM studies. Moreover, several combinations of formulations are barely explored. Regarding the simulation performance, we also show a new basic method that can be employed to evaluate the computing performance in transient numerical simulations.

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Section: Discussionmentioning

confidence: 99%

Fixed Grid Numerical Models for Solidification and Melting of Phase Change Materials (PCMs)

et al. 2019

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“…These materials are sustainable, biodegradable, nontoxic, and less flammable. On the other hand, their major drawbacks are that they are more corrosive than paraffin and more expensive [14,15]. Some nonparaffinic PCMs are presented in Table 2.…”

Section: Organic Materialsmentioning

confidence: 99%

“…Finally, they are compatible with most of the construction materials, they can be recycled, and their cost is relatively low. On the other hand, organic PCMs also exhibit some disadvantages based on their low energy storage capacity, low density, low thermal conductivity, and high flammability [8,9,14,15].…”

Section: Organic Materialsmentioning

confidence: 99%

“…Another disadvantage is the poor nucleating properties that resulting in supercooling of the liquid phase before crystallization. Additionally, inorganic PCMs are widely corrosive, in some cases toxic, show limited compatibility with construction materials, and they are rather expensive [14,15]. The advantages and disadvantages for both organic and inorganic PCMs are summarized in Table 3.…”

Section: Inorganic Materialsmentioning

confidence: 99%

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Towards Phase Change Materials for Thermal Energy Storage: Classification, Improvements and Applications in the Building Sector

2021

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The management of energy consumption in the building sector is of crucial concern for modern societies. Fossil fuels’ reduced availability, along with the environmental implications they cause, emphasize the necessity for the development of new technologies using renewable energy resources. Taking into account the growing resource shortages, as well as the ongoing deterioration of the environment, the building energy performance improvement using phase change materials (PCMs) is considered as a solution that could balance the energy supply together with the corresponding demand. Thermal energy storage systems with PCMs have been investigated for several building applications as they constitute a promising and sustainable method for reduction of fuel and electrical energy consumption, while maintaining a comfortable environment in the building envelope. These compounds can be incorporated into building construction materials and provide passive thermal sufficiency, or they can be used in heating, ventilation, and air conditioning systems, domestic hot water applications, etc. This study presents the principles of latent heat thermal energy storage systems with PCMs. Furthermore, the materials that can be used as PCMs, together with the most effective methods for improving their thermal performance, as well as various passive applications in the building sector, are also highlighted. Finally, special attention is given to the encapsulated PCMs that are composed of the core material, which is the PCM, and the shell material, which can be inorganic or organic, and their utilization inside constructional materials.

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“…Similarly, since their melting point is within the useful temperature range for thermal energy storage, they can be used in commercial applications as a more attractive alternative, instead of salts and paraffins [ 29 ]. Refined and virgin coconut oils were characterized by Kahwaji and White [ 30 ], who reported a relatively large heat of fusion and thermal stability making them feasible as a PCM for residential greenhouses.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Unripe and Mature Avocado Seed Oil in Different Proportions as Phase Change Materials and Simulation of Their Cooling Storage

2020

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Environmental problems have been associated with energy consumption and waste management. A solution is the development of renewable materials such as organic phase change materials. Characterization of new materials allows knowing their applications and simulations provide an idea of how they can developed. Consequently, this research is focused on the thermal and chemical characterization of five different avocado seed oils depending on the maturity stage of the seed: 100% unripe, 25% mature-75% unripe, 50% mature-50% unripe, 75% mature-25% unripe, and 100% mature. The characterization was performed by differential scanning calorimetry, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The best oil for natural environments corresponded to 100% matured seed with an enthalpy of fusion of 52.93 J·g−1, and a degradation temperature between 241–545 °C. In addition, the FTIR analysis shows that unripe seed oil seems to contain more lipids than a mature one. Furthermore, a simulation with an isothermal box was conducted with the characterized oil with an initial temperature of −14 °C for the isothermal box, −27 °C for the PCM box, and an ambient temperature of 25 °C. The results show that without the PCM the temperature can reach −8 °C and with it is −12 °C after 7 h, proving its application as a cold thermal energy system.

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Edible Oils as Practical Phase Change Materials for Thermal Energy Storage

Cited by 56 publications

References 46 publications

Fixed Grid Numerical Models for Solidification and Melting of Phase Change Materials (PCMs)

Fixed Grid Numerical Models for Solidification and Melting of Phase Change Materials (PCMs)

Towards Phase Change Materials for Thermal Energy Storage: Classification, Improvements and Applications in the Building Sector

Characterization of Unripe and Mature Avocado Seed Oil in Different Proportions as Phase Change Materials and Simulation of Their Cooling Storage

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