Heat transfer enhancement of paraffin wax using graphite foam for thermal energy storage

Carbon Foam Matrices Saturated with PCM for Thermal Protection Purposes

Heat transfer enhancement of paraffin wax using compressed expanded natural graphite for thermal energy storage

This article describes a group of thermal energy storage (TES) composites that combine TES and structural functionality. The composites are encapsulations of low melt temperature phase change materials (PCM) such as paraffin waxes in polymer matrices. Room temperature cured bisphenol-A epoxy and styrene–ethylene–butylene–styrene (SEBS) polymers are chosen as matrix materials because of their excellent chemical and mechanical properties. The polymeric network structure in the composite encapsulates the PCMs, which transform from the solid to the liquid phase. The PCMs provide the energy storage function via the solid–liquid latent heat effect. The resulting composite exhibits dry-phase transition in the sense that fluid motion of the PCM, when in the liquid phase, is inhibited by the structure of the polymer matrix. The polymer matrix is formulated to provide structural functionality. The latent heat, thermal conductivity and contact conductance, and structural moduli of composites having various PCM-to-matrix volume fractions are measured. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1240–1251, 2004

Polymeric phase change composites for thermal energy storage

Multifunctional materials are designed so as to meet specific requirements through tailored properties. Smart materials can be considered as multifunctional ones that have the ability to react upon an external stimulus, simulating, in this way, the behavior of nature’s materials. Furthermore, the introduction of biomemetics in the material science, allows the designing of materials with similar processes as nature does: building from molecules to complete structures. This paper focuses on the presentation of the various multifunctional materials reported in the literature and the processing means developed.

Multifunctional materials: engineering applications and processing challenges.

A novel multi-functional plate-like lamination that combines a thermal energy storage capability with a structural capability is described. The lamination consists of a paraffin impregnated porous graphitic core (the energy storage volume) encapsulated between rigid graphite/epoxy composite skins. Heat storage is via solid-liquid phase transition of the paraffin. Stacked laminations form a sandwich structure. A thermal response model shows that the graphite foam is an effective thermal conductivity enhancer to the imbedded paraffin. It will effectively immobilize liquid paraffin so that the thermal storage process will be unaffected by up to a 10g load. Furthermore, the foam can accommodate the relatively large specific volume change that accompanies paraffin phase transition. However, it does so at the expense of reduced thermal performance. Structural analysis shows that graphitic foam has a low strength and elasticity modulus, and the material displays tension-compression asymmetry. The paraffin fill is shown to increase the compressive ultimate strength and elasticity modulus. The use of carbon fiber/epoxy skin greatly enhances the overall strength of the structure.

Yuyi Shen

Papers

A multi-functional graphite/epoxy-based thermal energy storage composite for temperature control of sensors and electronics

A Multi-Functional Graphite/Epoxy-Based Thermal Energy Storage Composite