Materials used as PCM in thermal energy storage in buildings: A review

711

267

Various types of solid-liquid phase change materials (PCMs) have been reviewed for thermal energy storage applications. The review has shown that organic solid-liquid PCMs have much more advantages and capabilities than inorganic PCMs but do possess low thermal conductivity and density as well as being flammable. Inorganic PCMs possess higher heat storage capacities and conductivities, cheaper and readily available as well as being non-flammable, but do experience supercooling and phase segregation problems during phase change process. The review has also shown that eutectic PCMs have unique advantage since their melting points can be adjusted. In addition, they have relatively high thermal conductivity and density but they possess low latent and specific heat capacities. Encapsulation technologies and shell materials have also been examined and limitations established. The morphology of particles was identified as a key influencing factor on the thermal and chemical stability and the mechanical strength of encapsulated PCMs. In general, in-situ polymerization method appears to offer the best technological approach in terms of encapsulation efficiency and structural integrity of core material. There is however the need for the development of enhancement methods and standardization of testing procedures for microencapsulated PCMs. Abstract: Various types of solid-liquid phase change materials (PCMs) have been reviewed for thermal energy storage applications. The review has shown that organic solid-liquid PCMs have much more advantages and capabilities than inorganic PCMs but do possess low thermal conductivity and density as well as being flammable. Inorganic PCMs possess higher heat storage capacities and conductivities, cheaper and readily available as well as being non-flammable, but do experience supercooling and phase segregation problems during phase change process. The review has also shown that eutectic PCMs have unique advantage since their melting points can be adjusted. In addition they have relatively high thermal conductivity and density but they possess low latent and specific heat capacities. Encapsulation technologies and shell materials have also been examined and limitations established. The morphology of particles were identified as a key influencing factor on the thermal and chemical stability and the mechanical strength of encapsulated PCMs. In general, in-situ polymerization method appears to offer the best technological approach in terms of encapsulation efficiency and structural integrity of core material. There is however the need for the development of enhancement methods and standardization of testing procedures for microencapsulated PCMs.

Section: Non-paraffin Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Review of solid–liquid phase change materials and their encapsulation technologies

Darkwa

Kokogiannakis

2015

711

267

“…The first approximation proposed by Peippo et al [24], as shown in Equation (1), could be useful for determining the near optimal melting temperature of PCMs (T PCM,opt ) to be used in building envelopes. PCMs to be considered for building applications should have large latent heat of fusion, high specific heat and thermal conductivity, minimum sub-cooling, and be chemically stable, nontoxic, non-flammable and non-corrosive [25,26]. A summary of major PCMs suitable for building applications can be found in Refs.…”

Section: Materials Selectionmentioning

confidence: 99%

Nano-enhanced phase change materials for improved building performance

Lin

Sohel

2016

149

Nano-enhanced phase change materials (PCMs) have attracted increasing attention to address one of the key barriers (i.e. low thermal conductivity) to the wide adoption of PCMs in many industrial applications. This paper discusses the generic problem and key issues associated with appropriately using this new class of materials in buildings for effective thermal management and improved energy performance. An overview on major recent development and application of nano-enhanced PCMs as thermal energy storage media is provided. A case study based on a PCM ceiling ventilation system integrated with solar photovoltaic thermal (PVT) collectors is then performed to evaluate the potential benefits due to the dispersion of copper nanoparticles into the PCM base fluid of RT24. The results showed that this nano-enhanced PCM has higher melting and solidification rates than that of the pure PCM. Compared to the use of the pure PCM, 8.3% more heat was charged in and 25.1% more heat was discharged from the nano-enhanced PCM under the three winter test days. More research is needed to understand the fundamental mechanisms behind the PCM thermal conductivity enhancement through the dispersion of nanometer-sized materials and to investigate how these mechanisms drive building performance enhancement. Abstract: Nano-enhanced phase change materials (PCMs) have attracted increasing attention to address one of the key barriers (i.e. low thermal conductivity) to the wide adoption of PCMs in many industrial applications. This paper discusses the generic problem and key issues associated with appropriately using this new class of materials in buildings for effective thermal management and improved energy performance. An overview on major recent development and application of nano-enhanced PCMs as thermal energy storage media is provided. A case study based on a PCM ceiling ventilation system integrated with solar photovoltaic thermal (PVT) collectors is then performed to evaluate the potential benefits due to the dispersion of copper nanoparticles into the PCM base fluid of RT24. The results showed that this nano-enhanced PCM has higher melting and solidification rates than that of the pure PCM. Compared to the use of the pure PCM, 8.3% more heat was charged in and 25.1% more heat was discharged from the nano-enhanced PCM under the three winter test days. More research is needed to understand the fundamental mechanisms behind the PCM thermal conductivity enhancement through the dispersion of nanometer-sized materials and to investigate how these mechanisms drive building performance enhancement.

“…Regarding building applications, PCMs should have a melting/solidification temperature in the practical range of application, high latent heat of fusion and improved thermal conductivity [9]. PCMs should also have desirable thermophysical, kinetic, chemical, economic and environmental properties, as pointed out by several authors [9,[78][79][80][81][82][83][84][85][86]. The optimum incorporation of PCMs within construction systems and the evaluation of the energy performance of the building with these elements is very complex and challenging.…”

Section: Phase Change Materialsmentioning

confidence: 99%

Energy efficiency and thermal performance of lightweight steel-framed (LSF) construction: A review

Soares

Santos

Gervásio

et al. 2017

The improvement of the use of renewable energy sources, such as solar thermal energy, and the reduction of energy demand during the several stages of buildings' life cycle is crucial towards a more sustainable built environment. This paper presents an overview of the main features of lightweight steel-framed (LSF) construction with cold-formed elements from the point of view of life cycle energy consumption. The main LSF systems are described and some strategies for reducing thermal bridges and for improving the thermal resistance of LSF envelope elements are presented. Several passive strategies for increasing the thermal storage capacity of LSF solutions are discussed and particular attention is devoted to the incorporation of phase change materials (PCMs). These materials can be used to improve indoor thermal comfort, to reduce the energy demand for air-conditioning and to take advantage of solar thermal energy. The importance of reliable dynamic and holistic simulation methodologies to assess the energy demand for heating and cooling during the operational phase of LSF buildings is also discussed. Finally, the life cycle assessment (LCA) and the environmental performance of LSF construction are reviewed to discuss the main contribution of this kind of construction towards more sustainable buildings.