Temperature Control in (Translucent) Phase Change Materials Applied in Facades: A Numerical Study

Martin Tenpierik, Yvonne Wattez, Michela Turrin, Tudor Cosmatu and Stavroula Tsafou
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Martin Tenpierik: Department of Architectural Engineering and Technology, Faculty of Architecture and the Built Environment, Delft University of Technology, 2628 BL Delft, The Netherlands
Yvonne Wattez: Department of Architectural Engineering and Technology, Faculty of Architecture and the Built Environment, Delft University of Technology, 2628 BL Delft, The Netherlands
Michela Turrin: Department of Architectural Engineering and Technology, Faculty of Architecture and the Built Environment, Delft University of Technology, 2628 BL Delft, The Netherlands
Tudor Cosmatu: Department of Architectural Engineering and Technology, Faculty of Architecture and the Built Environment, Delft University of Technology, 2628 BL Delft, The Netherlands
Stavroula Tsafou: Department of Architectural Engineering and Technology, Faculty of Architecture and the Built Environment, Delft University of Technology, 2628 BL Delft, The Netherlands

Energies, 2019, vol. 12, issue 17, 1-16

Abstract: Phase change materials (PCMs) are materials that can store large amounts of heat during their phase transition from solid to liquid without a significant increase in temperature. While going from liquid to solid this heat is again released. As such, these materials can play an important role in future energy-efficient buildings. If applied in facades as part of a thermal buffer strategy, e.g., capturing and temporarily storing solar energy in so-called Trombe walls, the PCMs are exposed to high solar radiation intensities, which may easily lead to issues of overheating. This paper therefore investigates the melting process of PCM and arrives at potential solutions for countering this overheating phenomenon. This study uses the simulation program Comsol to investigate the heat transfer through, melting of and fluid flow inside a block of PCM (3 × 20 cm 2 ) with a melting temperature of around 25 °C. The density, specific heat and dynamic viscosity of the PCM are modeled as a temperature dependent variable. The latent heat of the PCM is modeled as part of the specific heat. One side of the block of PCM is exposed to a heat flux of 300 W/m 2 . The simulations show that once part of the PCM has melted convection arises transporting heat from the bottom of the block to its top. As a result, the top heats up faster than the bottom speeding up the melting process there. Furthermore, in high columns of PCM a large temperature gradient may arise due to this phenomenon. Segmenting a large volume of PCM into smaller volumes in height limits this convection thereby reducing the temperature gradient along the height of the block. Moreover, using PCMs with different melting temperature along the height of a block of PCM allows for controlling the speed with which a certain part of the PCM block starts melting. Segmenting the block of PCM using PCMs with different melting temperature along its height was found to give the most promising results for minimizing this overheating effect. Selecting the optimal phase change temperatures however is critical in that case.

Keywords: phase change materials; facades; heat transfer; computational fluid dynamics; convection (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (5)

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