Inclusion Of Phase Change Materials Research Articles

Influence of PCMs on thermal performance of wet fire protective clothing

The inclusion of phase change materials (PCMs) in firefighting protective clothing (FPC) has been previously shown to be beneficial during the exposure stage, but detrimental in the post-exposure, mainly due to PCM latent heat release towards the skin, after the exposure. It is unclear whether that is also the case for when the FPC is wet. Hence, in this study, a one-dimensional numerical approach is used to study the effect of PCM parameters (PCM mass, melting temperature) and global heat flux, on the thermal performance of a wet fire protective clothing. It is concluded that under wet conditions, the PCM amount, and its phase change temperature have a significant effect on thermal performance, depending on the heat exposure scenario considered. Great benefits are observed in introducing PCMs to prevent water condensation near the skin, but at the cost of greater PCM re-solidification skin damage.

Multiscale Finite Element Modeling of the Effect of Macro-Encapsulated Phase-Change Materials on the Thermal Performance of Hydronic Floor Heating Systems

Phase-change materials (PCMs) are commonly employed in building service equipment to regulate indoor temperatures and reduce energy consumption. This study conducted multi-scale finite element modeling to analyze the steady-state and dynamic thermal behavior of a hydronic radiant floor heating system integrated with macro-encapsulated PCMs. It predicted performance values for hydronic floor heating with and without macro-encapsulated PCMs. The study assessed the impact of the PCM volume fraction, heating water temperature, capsule thermal conductivity, and shape on the thermal performance of hydronic floor heating through various finite element models. The predictive capability of the finite element model was validated using experimental data, showing good agreement. Although the inclusion of PCMs lowered the floor temperature, it improved temperature distribution and retained heat when the system was inactive. The PCM volume fraction significantly influenced the performance of the hydronic floor. However, the shape of the macro-encapsulated PCM and thermal conductivity of the shell had minimal effects in the studied case. For instance, increasing the thermal conductivity of the shell of the PCM capsule fifty times from 0.3 to 15 W m−1 K−1 resulted in an increase in surface temperature by 1.2 °C.

Characterisation of the COMFORTBOARD gypsum board for thermal energy storage in buildings

Currently, the construction sector contributes considerably to the total energy consumption and greenhouse gas emissions into the atmosphere. Thermal energy storage (TES) systems are alternatives to increase the thermal inertia of buildings, aiming to use less energy, improve thermal comfort and reduce temperature fluctuations of interior spaces. One of the possible applications in buildings is to increase their thermal mass by impregnating phase change materials (PCM) in porous construction materials, e.g., gypsum boards. In this investigation, a commercial gypsum board impregnated with PCM (Knauf Comfortboard – BASF) was investigated by carrying out a structural and thermal characterisation. The thermal response obtained agrees with the product's technical data sheet provided by the supplier. The results of the thermal characterisation show that the inclusion of PCM in the gypsum board decreased the U-value by 2 % compared to the control sample (no PCM), increased the heat storage capacity by around 45 %, improved the thermal dynamic characteristics of the material by decreasing the thermal stability coefficient from 0.92 to 0.76 and increasing the thermal lag from 0.27 to 0.49 h. Our results sustain the potential application of commercial gypsum boards with PCM under environmental conditions across a wide range of daily temperature fluctuations (e.g., The North of Chile).

Study on Phase Change Material in Grooved Bricks for Energy Efficiency of the Buildings

Phase change materials (PCMs) are an interesting technology due to their high density and isothermal behavior during phase change. Phase change material plays a major role in the energy saving of the buildings, which is greatly aided by the incorporation of phase change material into building products such as bricks, cement, gypsum board, etc. In this study, an experiment has been conducted with three identical small chambers made up of normal, grooved and PCM-treated grooved bricks. Before the inclusion of PCM in grooved bricks, PCM material behavior has been studied by different techniques such as DSC, TG/DTA, SEM, and XRD. Thermal properties and thermal stability were investigated by differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA) respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to determine the microstructure and crystalloid phase of the PCM before and after the accelerated thermal cycling test (0, 60, 120). These three identical model rooms built were exposed at a temperature just above 40 °C with a heater. When the maximum outdoor temperature was 40-41 °C, then the temperature of the PCM-treated grooved chamber was 32-33 °C. The PCM-treated wall was tested and compared with a conventional and grooved wall. The difference between the PCM-treated grooved chamber and the untreated one was 8-9 °C. PCM-treated bricks provided more efficient internal heat retention in summer when the outside temperature increased.

Use of a form-stable phase change material to improve thermal properties of phosphate sludge-based geopolymer mortar

The development of eco-innovative building materials has become increasingly important due to their unique characteristics and environmental benefits. One such technology, the inclusion of phase change materials (PCMs), is highly effective in reducing energy consumption and increasing the thermal inertia of buildings. This study focuses on a novel PCM that encapsulates fatty acids in polyurethane foam and is incorporated into a geopolymer mortar matrix developed from phosphate industry by-products. The paper first outlines the structural and thermal properties of the developed geopolymer mortar (GP) and the form-stable phase change material (PU@PCM). It then investigates the influence of PU@PCM on the mechanical performance of the geopolymer mortar by conducting compressive tests, and the thermal performance by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and thermal conductivity (LFA) measurements. Results indicate that the prepared geopolymer mortar consists of a continuous three-dimensional network and that the developed PU@PCM provides a suitable operating temperature range (10–22 °C) for designing energy-efficient buildings, with good energy storage capacity (ΔHf = 164 J/g). Although the addition of PU@PCM resulted in a loss of compressive strength, the developed composites still meet the mechanical requirements for concrete applications, with the PU@PCM-rich composite reaching 29.5 MPa. Furthermore, the study of thermal performance shows that the inclusion of PU@PCM significantly improves the heat capacity and slightly reduces the thermal conductivity of the composites, with the PU@PCM-rich composite exhibiting 1.1 J/g.°C and 0.84 W/m.°C, respectively. Finally, cyclic DSC tests demonstrate that the composites are thermally stable even after 20 heating/cooling cycles. Overall, the geopolymer mortar with the highest PU@PCM content shows promise as a potential candidate for developing sustainable and energy-efficient buildings in the future. The developed material offers a combination of good thermal performance and acceptable mechanical strength, which are essential features for practical applications in construction.

Thermal properties of PEG-based form-stable Phase Change Materials (PCMs) incorporated in mortars for energy efficiency of buildings

The purpose of a phase change material (PCM) is to store/release energy during its transition from solid to liquid state, being able to count on a range of melting/crystallization temperatures comparable to environmental temperatures. The inclusion of a PCM in mortars, or in other construction elements, guarantees a reduction in energy consumption for heating and cooling of buildings, provided that the phase transition range of the PCM corresponds to the variation range of the environmental temperatures. This implies that a PCM with a suitable transition range must be identified for each climate zone. Two Poly-Ethylene Glycol (PEG)-based form-stable PCMs have been, then, produced with the intent of include them in mortars applied in buildings located in different climatic zones, i.e. continental and Mediterranean regions. The form-stable PCMs were realized starting from two PEGs possessing different molecular weights, i.e. PEG800 and PEG1000, characterized by different ranges of melting/crystallization temperatures. The PEGs were included in flakes of a porous stone, i.e., Lecce Stone (LS), to produce two form-stable PCMs, namely: LS/PEG800 and LS/PEG800_PEG1000 (50/50 wt%). In the present paper, the thermal performance of the PCM-modified mortars was assessed in a climatic chamber able to simulate the variation of environmental temperatures in the two climatic zones under consideration. The effectiveness of the original PCMs to mitigate indoor temperature fluctuations was, then, assessed: it was found that the mortar formulations containing the mixed PCM (i.e., LS/PEG800_PEG1000 compound) offered the best advantage in reducing cooling and heating needs by 8 % and 13 %, respectively. On the basis of these results, the energy savings for indoor heating/cooling were calculated, with the corresponding reduction in costs: the inclusion of PCM LS/PEG800_PEG1000 in the mortars, especially those based on hydraulic lime, produced a noticeable reduction in the cooling cost, i.e. around 8 % during the summer, and 12 % during the spring and autumn seasons for internal heating of buildings located in the Mediterranean area. The time lag between the maximum and minimum temperatures with respect to the external (which simulates the environmental one) temperature was also evaluated: the cement-based mortar containing the mixed PCM generally performed the best, regardless of the climatic zone taken as a reference.

Improving building thermal comfort through passive design – An experimental analysis of phase change material 3D printed concrete

As the effects of climate change are felt around the world, it is important to consider more sustainable practices in every industry to reduce greenhouse gas emissions and preserve resources. Sustainable practices in the building sector and construction industry include incorporating passive design solutions into the building design and constructing with recycled materials. In this research the main passive design solution considered is thermal energy storage by latent heat capacity of phase change materials (PCMs). Construction with bricks is widely used in the developing world, allowing much potential for the use of recycled brick aggregate in construction composites. This research is the first of its kind on PCM inclusion by aggregate impregnation of recycled brick aggregate in 3D printed concrete (3DPC). Two cavity façade sections are 3D printed using two concrete mix designs - the first, in which 64% of the natural aggregate in the mix is replaced with recycled brick aggregate, and the second, adjusted from the first by an addition of PCM to the pores of the recycled brick aggregate by vacuum impregnation, creating concrete with a total average latent heat capacity of 7360 J/kg. These façade sections are used in four sets of thermal tests in Stellenbosch, South Africa. It is concluded that by latent heat storage, PCM delays heat transfer through the PCM-3DPC passive design façade section, significantly increasing the time that internal ambient temperatures remain within standardised ranges of thermal comfort, and reducing the maximum internal ambient temperatures by up to 3.9 °C. Minimal leakage of PCM is proven by effectiveness of the PCM in the PCM-3DPC façade section after five months of exposure to outdoor ambient spring and summer conditions.

Development and Performance of Eco-Sustainable Form-Stable Phase Change Materials (PCMs) for Mortars to Be Applied in Buildings Located in Different Climatic Areas

The growing concern for the environment and the depletion of raw materials such as fossil fuels is driving research towards the exploitation of new materials and the development of new technologies. Phase-change materials (PCMs) are increasingly used to reduce the energy required for the heating/cooling of buildings. The biggest challenge is to find a PCM with suitable characteristics able to meet the needs of the different climates in which it is placed. The originality of our research, therefore, lies in the possibility of selecting the most appropriate polymer to produce a PCM suitable for different climatic conditions that characterize the area in which a building is located. Furthermore, the proposed form-stable PCMs were obtained by including low-toxic, low-flammability polymers in waste stone fragments, according to the principles of a circular economy. These original sustainable PCMs were then used as aggregates by adding them to mortars (based on air lime, hydraulic lime, cement and gypsum). The mortars containing the PCMs were analyzed in fresh (workability) and hardened (flexural and compressive strengths and thermal characteristics) states. The results obtained showed that although the inclusion of PCM reduced the mechanical properties of the mortars, good mechanical properties can be still achieved by using an adequate binder content. The produced mortars were also analyzed by thermal analysis to assess how the addition of a PEG-based PCM affected their thermal behavior. The original PCMs were proven to be effective in improving the indoor temperature when included in mortars applied as plasters.

Life cycle assessment of the inclusion of phase change materials in lightweight buildings

This research evaluates environmental impact of including phase change materials in the envelope of lightweight buildings constructed off-site with dimensions 2.5 × 2.5 × 2.43 m3, located in the cities of Antofagasta and Calama, both in Chile. These cities are located in a cold desert climate zone, corresponding to a Köppen Climate Classification subtype “BWk”, with an average annual temperature difference of 4.8 °C.To evaluate the environmental impact quantitatively from “cradle to grave” life cycle assessment was used, it is a methodology based on International Organization for Standardization 14,040 and 14,044 standards. With this methodology, the manufacturing and operational phases and environmental payback period were evaluated.Results show that phase change materials addition in walls and roof of a building decreases electric energy (52.8 % in Antofagasta and 36.3 % in Calama) consumption and environmental impact while in operation, corresponding to 51.4 % and 84.4 % in the cities of Antofagasta and Calama, respectively.In addition, cubicles with phase change materials exhibit an environmental payback period below 15 %. Therefore, a decision of using phase change materials for lightweight buildings could be made in any subtype “BWk” area of Köppen climate classification.

Effects of paraffin additives, as phase change materials, on the behavior of a traditional lime mortar

This study refers to the inclusion of phase change materials (PCMs) in porous building materials as an alternative means of improving their thermal behavior, assessing the changes caused in their physical–mechanical and durability properties. Specifically, an organic paraffin wax was selected for direct incorporation into lime mortars using different concentrations by weight. The results show that PCMs improve the thermal properties of the mortar while reducing its accessible porosity. This increases the mortars’ resistance to water and soluble salts. However, excessive PCM content causes stresses within the mortar that can jeopardize its structure.

Computational design of a Massive Solar-Thermal Collector enhanced with Phase Change Materials

A cement-based device that can meet, partially or completely, the heating loads of a building by absorbing the solar radiation and converting it into thermal energy can be defined as a Massive Solar-Thermal Collector. The absorbing material for the incoming radiation is made of a cementitious composite, generally concrete, and flowing water inside tubes acts as a heat transfer medium. For an optimized performance, during periods of solar radiation, the device has to efficiently conduct the heat flow from the absorbing surface of the collector and transfer this heat energy to the water. Then, when the radiation is reduced or became null, the device should retain as much as possible the heat energy, reducing the heat that is escaping the collector and consequently the losses to the surrounding environment. In this work, by performing a parametric analysis, different absorbing materials are tested with the objective of finding the best configuration that maximizes the energy efficiency of the collector. Cementitious materials, in combination with Phase Change Materials with distinct melting (and solidification) temperatures, are selected as candidate absorbing materials. The weather variables of an entire year and for two different locations are considered to evaluate the behavior of these devices in opposite climates. After numerical simulations, in where an enthalpy-based finite element formulation is used to solve the physical problem, the obtained results allow to conclude that the inclusion of Phase Change Materials within the absorber material of the collectors, if it is done in a correct way, can improve the energy performance of these devices. In this study, 34 °C and 53 °C are chosen as the most appropriated melting temperatures, which conduct to considerable improvements in the achieved performances, and in both warm and cold climates.

Foam Concrete Produced with Recycled Concrete Powder and Phase Change Materials

In construction industry, phase change materials (PCMs), have recently been studied and found effective in increasing energy efficiency of buildings through their high capacity to store thermal energy. In this study, a combination of Capric (CA)-Palmitic acid (PA) with optimum mass ratio of 85–15% is used and impregnated with recycled concrete powder (RCP). The resulting composite is produced as foam concrete and tested for a series of physico-mechanical, thermal and microstructural properties. The results show that recycled concrete powder can host PCMs without leaking if used in proper quantity. Further, the differential scanning calorimetry (DSC) results show that the produced RCP/CA-PA composites have a latent heat capacity of 34.1 and 33.5 J/g in liquid and solid phases, respectively, which is found to remain stable even after 300 phase changing cycles. In this regard, the indoor temperature performance of the rooms supplied with composite foams made with PCMs, showed significantly enhanced efficiency. In addition, it is shown that inclusion of PCMs in foam concrete can significantly reduce porosity and pore connectivity, resulting in enhanced mechanical properties. The results are found promising and point to the suitability of using RCP-impregnated PCMs in foam composites to enhance thermo-regulative performance of buildings. On this basis, the use of PCMs for enhanced thermal properties of buildings are recommended, especially to be used in conjunction with foam concrete.

Potential Phase Change Materials in Building Wall Construction-A Review.

Phase change materials (PCMs) are an effective thermal mass and their integration into the structure of a building can reduce the ongoing costs of building operation, such as daily heating/cooling. PCMs as a thermal mass can absorb and retard heat loss to the building interior, maintaining comfort in the building. Although a large number of PCMs have been reported in the literature, only a handful of them, with their respective advantages and disadvantages, are suitable for building wall construction. Based on the information available in the literature, a critical evaluation of PCMs was performed in this paper, focusing on two aspects: (i) PCMs for building wall applications and (ii) the inclusion of PCMs in building wall applications. Four different PCMs, namely paraffin wax, fatty acids, hydrated salts, and butyl stearate, were identified as being the most suitable for building wall applications and these are explained in detail in terms of their physical and thermal properties. Although there are several PCM encapsulation techniques, the direct application of PCM in concrete admixtures is the most economical method to keep costs within manageable limits. However, care should be taken to ensure that PCM does not leak or drip from the building wall.

Soft and Stretchable Liquid Metal Composites with Shape Memory and Healable Conductivity.

Shape memory composites are fascinating materials with the ability to preserve deformed shapes that recover when triggered by certain external stimuli. Although elastomers are not inherently shape memory materials, the inclusion of phase-change materials within the elastomer can impart shape memory properties. When this filler changes the phase from liquid to solid, the effective modulus of the polymer increases significantly, enabling stiffness tuning. Using gallium, a metal with a low melting point (29.8 °C), it is possible to create elastomeric materials with metallic conductivity and shape memory properties. This concept has been used previously in core-shell (gallium-elastomer) fibers and foams, but here, we show that it can also be implemented in elastomeric films containing microchannels. Such microchannels are appealing because it is possible to control the geometry of the filler and create metallically conductive circuits. Stretching the solidified metal fractures the fillers; however, they can heal by body heat to restore conductivity. Such conductive, shape memory sheets with healable conductivity may find applications in stretchable electronics and soft robotics.

Thermal Energy Storage by the Encapsulation of Phase Change Materials in Building Elements-A Review.

The energy sector is one of the fields of interest for different nations around the world. Due to the current fossil fuel crisis, the scientific community develops new energy-saving experiences to address this concern. Buildings are one of the elements of higher energy consumption, so the generation of knowledge and technological development may offer solutions to this energy demand, which are more than welcome. Phase change materials (PCMs) included in building elements such as wall panels, blocks, panels or coatings, for heating and cooling applications have been shown, when heating, to increase the heat storage capacity by absorbing heat as latent heat. Therefore, the use of latent heat storage systems using phase change materials (PCMs) has been investigated within the last two decades. In the present review, the macro and micro encapsulation methods for construction materials are reviewed, the former being the most viable method of inclusion of PCMs in construction elements. In addition, based on the analysis of the existing papers on the encapsulation process of PCMs, the importance to pay more attention to the bio-based PCMs is shown, since more research is needed to process such PCMs. To determine its thermophysical and mechanical behavior at the micro and macro levels, in order to see the feasibility of substituting petroleum-based PCMs with a more environmentally friendly bio-based one, a section devoted to the excellent PCM with lightweight aggregate (PCM-LWA concrete) is presented due to the lack of description given in other reviews.

Investigation of the operational performance and efficiency of an alternative PV + PCM concept

The significance of the temperature effect on the performance of photovoltaics (PVs) has implied the necessity to develop PV cooling methods in recent years. In this research, the inclusion of phase change materials (PCMs) through an alternative type of enclosure in tubular shape was proposed and investigated as an option of mitigating the PV operating temperature to enhance their efficiency and lifetime. Two PVs incorporating different PCMs (PV + PCM systems) and a conventional PV module (reference case) were experimentally tested to assess their energy performance under the Mediterranean conditions in Chania, Crete. As PCMs employed were selected Paraffins RT 27 and RT 31. The results indicated that a peak temperature decrement of 6.4 °C and 7.5 °C could be observed by using 260 g of PCM27 and PCM31, respectively. Hence, PV + PCM27 and PV + PCM31 systems exhibited increased energy generation by 4.19% and 4.24%, respectively, while the increment in the PV conversion efficiency by PCM integration ranged from 2.86 to 4.19%. The proposed configuration of PCM enclosures took advantage of the synergistic effect of wind, as demonstrated by the recorded daily temperature profiles of the PV + PCM27 and PV + PCM31 systems, even after the time of complete PCMs' melting.

Soft Actuators Based on Liquid-Vapor Phase Change Composites.

Liquid-vapor phase change materials (PCMs), capable of significant volume change, are emerging as attractive actuating components in forming advanced soft composites for robotic applications. However, the novel and functional design of these PCM composites is significantly limited due to the lacking of the fundamental understanding of the mechanical properties, which further inhibits the broad applications of PCM based materials in the engineering structures requiring large deformation and high loading capacity. In this study we fabricate PCM-elastomer composites exhibiting large deformation and high output stress. Thermomechanical properties of these composites are experimentally and theoretically investigated, demonstrating enhanced deformation and loading capacity due to the induced vapor pressure. By controlling the distribution and content of the PCM inclusions, structures with tunable deformability under a relatively small strain in comparison with traditional soft materials are fabricated. Accompanying with the asymmetrical friction and deformation, complex locomotion and adaptable grabbing function are achieved with excellent performance.

Thermal behavior of cement mortar embedded with low-phase transition temperature PCM

This study examines the thermal behavior of cement mortar incorporating low-phase transition temperature phase change materials (PCM) (around the freezing point of concrete pore solutions) in an attempt to develop a novel strategy to reduce the expected number of freeze-thaw cycles concrete experiences and possibly to improve the frost resistance. To determine a viable inclusion method for PCM, thermal responses of mortars with two different PCM inclusion methods were tested under a 24-h sinusoidal temperature history, with the maximum and minimum ambient temperatures of 9 °C and −5°C, respectively, considering typical winter climate conditions in South Korea: (1) direct inclusion of non-treated raw PCM; and (2) inclusion of PCM-filled highly absorptive lightweight aggregates (LWA). In addition, another series of testing was conducted to identify the effect of phase transition temperature distribution on the thermal response of cement mortar: (1) inclusion of multi PCMs with three different transition temperatures (4.5 °C, 2.0–2.5 °C, and −0.5 °C); and (2) inclusion of single PCM with a phase transition temperature of 4.5 °C. Lastly, to see the effect of partial PCM embedment, thermal responses of cement mortars overlaid with three different PCM-embedment depths (20 mm, 30 mm, and 40 mm) were evaluated. Results have shown that the minimum specimen temperature was successfully raised by the addition of low-phase transition temperature PCMs. Also, it was revealed that the use of multi PCMs-filled LWA performed most effectively in terms of thermal and mechanical properties as compared to other incorporation methods. The partial PCM embedment improved the thermal performance, but there was no significant effect of PCM embedment depth.

Thermo-optic durability of cool roof membranes: Effect of shape stabilized phase change material inclusion on building energy efficiency

Cool roofs represent an acknowledged passive cooling technique aimed at reducing the amount of solar radiation absorbed by buildings and producing indoor overheating, particularly, in summer conditions. Cool roofs owe their unique behavior to improved thermo-optic performances which, however, have been shown to deteriorate when exposed to intense atmospheric weathering. In this context, the authors produced a shape stabilized composite with improved heat storage performance, by adding 15, 25, or 35 weight percentage of non-encapsulated phase change materials (PCMs) to the original blend of a liquid waterproof-polyurethane-based cool membrane. The behavior of such composite material, when exposed to accelerated temperature, humidity, and UV radiation cycles by means of standardized long-term weathering tests (QUV test), is investigated. The final aim of the study is to clarify if the PCM inclusion could help the membrane to better behave during the course of the time, because of thermal stress reduction. In order to do so, controlled atmospheric forcing and surface temperature continuous monitoring are used to investigate the degradation of the membrane produced by the imposed weathering stress. Results show that the introduction of 25% PCM in weight optimizes the superficial finishing characteristics of the prototype, allowing to maintain a more stable thermo-optic behavior, reducing both the thermal-induced degradation and the leakage phenomenon.

Multiphysics analysis of effects of encapsulated phase change materials (PCMs) in cement mortars

There is growing interest in the use of phase change materials (PCMs) in the building industry, particularly in cementitious materials. However, the phenomenological interactions between PCMs and cement remain poorly understood and need to be clarified.In this study, mechanical tests were performed on several mortars modified by adding different amounts of PCM (5, 10, and 15 wt%).A series of experiments, including thermophysical analyses (thermogravimetric analysis and semi-adiabatic calorimetry), microstructural analyses (X-ray tomography, mercury intrusion porosimetry, scanning electron microscopy) and Fourier transform infrared spectroscopy provided phenomenological explanations of the evolution of the mechanical properties of these composites.It was determined that the degradation of the mechanical performance of the PCM-mortar composites was due to not only weak PCM inclusions but also a decrease in the degree of hydration of the composites, which induced a special evolution of the pore microstructure.