Addition Of Phase Change Materials Research Articles

Inclusion of microencapsulated phase change materials in waterborne paints to enhance radiative cooling performance

Radiative cooling materials are a promising technology for reducing energy demand for thermal control in buildings and surfaces. Paint formats are versatile and relatively inexpensive implementations of this technology. Waterborne polyurethane paints are environmentally friendly coating systems that possess high abrasion resistance and durability. However, the implementation of radiative cooling in polyurethane paints is limited due to their less favorable optical properties. In this work, the addition of phase change materials (PCM) to the paint formulation to enhance cooling performance is investigated. Capric acid, encapsulated in silicon dioxide particles via a sol–gel process, was selected as the PCM, and barium sulfate particles were used as paint pigments. At a fixed total particle volume concentration, the incorporation of PCM increases the effective heat capacities of paints. However, the solar reflectance decreases as the PCM volume concentration increases, especially above 0.25. An outdoor test reveals that the inclusion of the PCM reduces the heat load in the paint and consequently enables sub-ambient cooling. This study suggests that the PCM components can enhance the cooling performance of radiative cooling paint systems that struggle to achieve sub-ambient cooling.

Cyclic heat-generation and storage capabilities of self-heating cementitious composite with an addition of phase change material

This study explored the efficiency of the phase-change materials (PCM) to improve the heat storage capacity of carbon nanotube (CNT) and carbon fiber (CF) based self-heating cementitious composites. Composites were prepared with 0.8 wt% CNT and 0.2 wt% CF as conductive fillers, and five different PCM contents (0, 5, 10, 20, and 30 wt%), and their electrical conductivities, thermal conductivities, and compressive strengths were measured. To determine the self-heating capability, the heat-generation and heat-storage capabilities of the composites were investigated using monotonic and cyclic heating/cooling tests. The results of these tests were analyzed through a differential scanning calorimetry and micro-computed tomography, which showed that the PCM particles with high latent heat were well dispersed in the composites, improving the heat storage capacity. Therefore, it can be said that the addition of PCM may improve heat storage capacity and enhance energy efficiency of the cement-based self-heating composites.

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.

Comparison of thermal conductivity of foamed geopolymers containing phase change materials

The aim of this work was to investigate the effect of Phase Change Materials on the insulation properties - thermal conductivity coefficient [λ], of fabricated foamed geopolymer panels. Phase Change Materials have been widely reported in the public literature, making them increasingly popular in recent times. PCMs have the ability to accumulate heat, which they can absorb or release due to thermal transformation, which contributes to energy efficiency. This paper presents the results of research on geopolymers based on fly ash with the addition of microencapsulated and macroencapsulated phase change materials (PCMs). Geopolymer composites were prepared by adding 0%, 5%, 10% and 15% PCM and the curing process was carried out at 60°C. Three different phase change materials with melting points of 28°C (MicroCapsPCM28 (Slovenia)) and 25°C and 42°C (PX25 and GR42 (Germany), respectively) were used. All the phase change materials used belong to the paraffin group. The obtained composite sheets were subjected to thermal conductivity tests in 3 temperature ranges (0-20°C; 20-40°C; 30-50°C). The paper also presents the density results of the foamed composites investigated, as well as the visual evaluation and the morphology of the porous structure using scanning electron microscopy. As a result of the study, it was found that foamed geopolymer composites without PCM addition have lambda coefficient values of 0.06 - 0.07 [W/m*K], while with the addition of phase change materials 0.07 - 0.085 [W/m*K]. The obtained test results give the potential to use these materials in construction as insulating materials. The use of these substances in building partitions results in the decrease of daily temperature amplitudes inside the building, as well as in the phase shift of the time of release of stored heat.

Comparative Study of Two Materials Combining a Standard Building Material with a PCM

Phase change materials (PCMs) have the ability to store thermal energy and make it available at a later stage to keep indoor temperature within a specific range and achieve better thermal comfort in buildings. This study focuses on the performances of materials obtained by combining a standard building material with a PCM. In particular, two different materials mixed with the same PCM are considered under the same climatic conditions. The related thermal behavior is assessed in the framework of numerical simulations conducted with ANSYS Fluent assuming parameters representative of a city located in Europe. The results show that the addition of PCM to concrete and bricks can improve the thermal inertia of the resulting material.

Development of Novel Polypropylene Syntactic Foams Containing Paraffin Microcapsules for Thermal Energy Storage Applications

polypropylene (PP) syntactic foams (SFs) containing hollow glass microspheres (HGMs) possess low density and elevated mechanical properties, which can be tuned according to the specific application. A possible way to improve their multifunctionality could be the incorporation of organic Phase Change Materials (PCMs), widely used for thermal energy storage (TES) applications. In the present work, a PCM constituted by encapsulated paraffin, having a melting temperature of 57 °C, was embedded in a compatibilized polypropylene SF by melt compounding and hot pressing at different relative amounts. The rheological, morphological, thermal, and mechanical properties of the prepared materials were systematically investigated. Rheological properties in the molten state were strongly affected by the introduction of both PCMs and HGMs. As expected, the introduction of HGMs reduced both the foam density and thermal conductivity, while the enthalpy of fusion (representing the TES capability) was proportional to the PCM concentration. The mechanical properties of these foams were improved by the incorporation of HGMs, while they were reduced by addition of PCMs. Therefore, the combination of PCMs and HGMs in a PP matrix generated multifunctional materials with tunable thermo-mechanical properties, with a wide range of applications in the automotive, oil, textile, electronics, and aerospace fields.

Printability, Thermal and Compressive Strength Properties of Cementitious Materials: A Comparative Study with Silica Fume and Limestone

Over the past decade, 3D printing in the construction industry has received worldwide attention and developed rapidly. The research and development of cement and concrete products has also become quite well-established over the years, while other sustainable materials receive considerably lower attention in comparison. This study aims to investigate the influence of the two most commonly used sustainable cementitious materials i.e., silica fume and limestone powder, on printability, thermal and mechanical properties of fly ash-Portland cement blends. Ternary blends containing Portland cement, fly ash and silica fume or limestone powder are prepared, whereas phase change material (PCM) is introduced to improve the thermal behavior. Based on the rheological properties and concurrent 3D concrete printing, improved buildability of the modified mixtures is linked to their static yield stress. Anisotropic mechanical properties are observed for 3D printed specimens, while cast specimens exhibit a maximum 41% higher compressive strength due to better material compaction. It is clear from the results that addition of silica fume and limestone powder ranged from 5% to 10%, reducing the anisotropic mechanical properties (maximum 71% and 68% reduction in anisotropic factor, respectively) in the printed specimens. The PCM addition ranged from 5% to 10% and improved thermal performance of the mixtures, as measured by a decrease in thermal conductivity (9% and 13%) and an increase in volumetric heat capacity (9% and 10%), respectively. However, the PCM-containing mixtures show around 29% reduction in compressive strength, compared to the control specimen, which necessitates new material design considering matrix strengthening methods.

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.

Thermal properties of geopolymer composites containing microencapsulated phase change materials

AbstractThe main objective of this paper is to investigate the possibility of using phase change materials (PCMs) as one of the components of a geopolymer and to determine the effect of PCMs addition on the thermal properties of the geopolymer composite obtained. This paper presents the results of geopolymers produced based on fly ash with the addition of microencapsulated PCMs. The geopolymer composites were prepared by adding 0%, 5%, 10%, and 15% PCM, and the curing process was carried out in two temperature ranges: 60°C and 75°C. A PCM with a melting point of 28°C (MicroCapsPCM28‐slurry [Slovenia]) was used. The composites were subjected to thermal conductivity tests in three temperature ranges (0–20°C; 20–40°C; and 30–50°C). This was followed by specific heat and density tests. In addition, the morphology of the geopolymers was determined by scanning electron microscopy. The results showed that the addition of PCMs to the geopolymer materials significantly reduces their thermal conductivity index (compared to the reference sample). Furthermore, the addition of microencapsulated phase‐change materials caused changes in the specific heat of the materials analyzed.

Phase change material infused recycled brick aggregate in 3D printed concrete

In this paper the effects of the addition of a paraffin phase change material on the strength and printability of 3D printed concrete are studied. Phase change materials are latent heat storing materials, which garner and release large amounts of energy as they change phase. The addition of phase change materials to concrete produces a composite material with maximised latent and sensible heat storage capacity. Used in buildings, this composite material has the ability to minimise unwanted heat transfer across the building envelope.An existing mix design (RBA-3DPC), in which 64% of the natural aggregate in a 3D printable concrete (3DPC) had been replaced with recycled brick aggregate, is adjusted by adding phase change material to the pores of the recycled brick aggregate by vacuum impregnation, creating PCM-3DPC. Rheological characterisation tests are performed on reference mix designs (3DPC and RBA-3DPC) and the PCM-3DPC mix design, and used in a buildability model to validate the number of printable layers. Mechanical characterisation tests including cube strength tests, direct tensile tests and uniaxial compressive tests are performed on cast and printed specimens of the mix designs. There is no existing research on the effects of the combined addition of recycled brick aggregate and phase change material in 3D printed concrete.It is concluded that the PCM-3DPC has the highest number of printable layers predicted by the model and realised by a cylindrical column print and overall, PCM-3DPC has greater strength compared to RBA-3DPC, and lower strength compared to 3DPC. The PCM-3DPC exceeds the RBA-3DPC interlayer tensile strength by 6%, intralayer compressive strength by 43% and interlayer compressive strength by 9%, and subceeds the 3DPC interlayer tensile strength by 15% and interlayer compressive strength by 13%.

Numerical simulation of hybrid battery thermal management system combining of thermoelectric cooler and phase change material

In this study, a hybrid BTMS (battery thermal management system) that combines TEC (thermoelectric cooler) and PCM (phase change material) is shown. The PCM absorbs heat and occurs in phase change, which stores the heat from batteries. The TECs act as a heat pump, takes away the excess heat in the PCM through the fins, and control the temperature of the PCM below the phase transition temperature as much as possible, which can prevent it from melting completely and losing the ability to keep the battery temperature stable. By comparative analysis, the addition of PCM can obtain better temperature uniformity, the temperature difference was controlled below 6 °C, and CPCM with higher thermal conductivity was more suitable for the hybrid BTMS, at 1200 s, the maximum temperature of the model with 30% EG/RT44HC was 10.3 °C lower than that with pure RT44HC. When the fill thickness of CPCM increases, the temperature control time can be extended, but the performance of TEC will decrease. For this model, the arrangement direction of the fins should be perpendicular to the direction of the battery which has higher thermal conductivity, heat from batteries can be effectively transferred to the fins more and faster.

Improving the building energy flexibility using PCM-enhanced envelopes

Pre-formed internal insulative panels with impregnated phase change materials (PCM) can significantly increase both the thermal resistance and thermal capacitance of existing or new building envelopes, thereby improving the overall energy performance of buildings. A further advantage is that such measures have the potential to enhance the energy flexibility of the building, thereby offering the possibility of participation in demand side management measures such as demand response programmes. The current literature on building envelope physics lacks research on energy flexibility and demand response, especially in the context of the building envelope integrated design with high latent heat materials such as PCM for demand response applications. The objective of the current study is to examine how the addition of PCM impregnated building envelopes affects both the thermal performance of the building envelope, as well as the wider building energy characteristics when subject to different demand response events. A reference building is utilised, which is a residential detached house with a floor area of 160 m 2 and a south-easterly facing aspect. Another contribution of this study is proposing new energy flexibility indicators taking into consideration envelope pre-cooling and pre-heating periods prior to the demand response event. Simulation results show that shorter envelope pre-cooling periods (0.5 hr) together with longer demand response periods (4 h) are preferable for all envelopes to achieve the maximum power curtailment for cooling. PCM-enhanced envelopes are shown to give best cooling demand shifting and energy flexibility efficiency. The MW PCM-1 and MW PCM-2 envelopes have the highest flexibility efficiency with a value of 244%. For heating, gypsum board enhanced with PCM retrofitted on the envelopes are shown to give an overall good performance in energy flexibility efficiency and in power curtailment compared to the other building envelopes in all durations of an energy flexibility event. For heating, the maximum energy flexibility efficiencies range from 250% for the LW Gypsum Board envelope to 356% for the LW PCM-2 envelope. • Energy flexibility is mapped for building envelopes with sensible and latent TES. • Building envelopes are optimised for different demand response events. • An energy flexibility sensitivity analysis algorithm is developed in EnergyPlus. • In buildings with only sensible TES short demand response events should be used. • Envelopes with PCM have better energy flexibility in long demand response events.

Magnesium oxychloride cement with phase change material: Novel environmentally-friendly composites for heat storage

To solve heat energy storage of building enclosure systems, phase change materials (PCMs) were implemented into magnesium oxychloride cement (MOC) to form a MOC-PCM composite. Such composites possess sufficient mechanical strength for specific usage and high heat storage efficiency. The chemical and physical properties of raw materials were investigated as well as fresh composite mixture rheology. On matured samples, structural, mechanical, hygric, and thermal properties were tested. The results suggest that the enrichment of MOC with PCM particles causes an increase in porosity, hence a decrease in the specific density of the composites. With each addition of PCM the reduction of mechanical properties of the composite material occurs, where the maximum reduction in flexural and compressive strength for the sample with 40 wt % of PCM is around 80%. The low strength of the composite is compensated by excellent thermal properties that are required for its intended application. The enthalpies of phase changes increased linearly with the dosage of PCM and can contribute to the passive moderation of temperature fluctuations. The developed composites can find use in building engineering in the form of indoor cladding panels, facing slabs ceiling boards, etc. Which can be beneficially applied for example in the passive cooling of attic rooms and retrofitting of the present building stock.

Structure parameter analysis and optimization of photovoltaic-phase change material-thermoelectric coupling system under space conditions

Phase change material (PCM) as highly efficient temperature control material has been used in terrestrial photovoltaic-thermoelectric (PV-TE) coupling system to achieve higher power generation efficiency. However, the mass increase results from addition of PCM limits its application in space system. In present paper, a two-dimensional model for PV-PCM-TE coupling system was developed to investigate the energy transfer and conversion performance under space conditions. Firstly, the suitable PCM was selected, both the pure PCM and its metal foam composite PCM (MFCPCM) are used. Then, performance comparison for PV-TE, PV-PCM-TE and PV-MFCPCM-TE systems were performed. The results show PCM can significantly enhance the total efficiency, but causes power density dramatically decreasing. The average total efficiencies for PV-TE, PV-PCM-TE and PV-MFCPCM-TE are 29.50%, 30.50% and 30.61%, and the corresponding average power density are 30.34 W/kg, 22.39 W/kg and 21.20 W/kg, respectively. After that, an orthogonal experiment was designed to reveal the effects of structure parameters on power generation efficiency and power density of PV-MFCPCM-TE system. The optimum geometric parameters to achieve the best power generation efficiency and power density were derived. The results show that after optimization, the average total efficiency and power density of PV-MFCPCM-TE are 30.83% and 31.35 W/kg, both of them are higher than those of the traditional PV-TE system (29.50% and 30.34 W/kg). The present work is beneficial for the application of PV-PCM-TE system in space conditions.

Evaluation of efficiency of double slope solar still and drinking water yield using silver nanoparticle mixed with phase change material

ABSTRACT This study shows the contribution of silver nanoparticles mixed with macro-encapsulated phase change material (PCM) in a double slope solar still. Experiments are carried out in three different depths and settings, first using simple double slope solar still, then by addition of PCM, and finally using PCM mixed with silver nanoparticles. Results obtained are compared during the sunshine period and also after sunset. The study shows that the silver nanoparticles in PCM results in reducing the yield and efficiency of the double slope solar still by 7.64% and 5.26% during the charging period. However, it continues to deliver potable water even after sunset due to the stored latent heat in the PCM. The higher thermal capacity of the PCM and the higher thermal conductivity of the silver nanoparticles resulted in a 16% increase in drinking water yield and a 62.53% rise in the thermal efficiency of the double slope solar still. The final cost per liter of the potable water generated using the double slope solar still was reduced to 3.80 INR and the payback time is 2 years which can be reduced further using PCM and nano-enhanced PCM inside the solar still.

Preparation and Characterization of Phase Change Polyester Fiber

In this work, a phase change material was synthesized from diphenyl methane diisocyanate and polyethylene glycol. Phase change material and polyester masterbatches were blended and granulated by a twin-screw extruder to make blend master batch. According to the result of FTIR, no transesterification reaction was found between phase change material and polyester. Process flow of melt spinning was determined by the results of DSC. The addition of phase change material did not have a big impact on spinnability. Thermo-regulated polyester fibers were prepared by melt spinning. The masterbatch of thermo-regulated polyester has a good fiber forming property. Thermo-regulated polyester fiber has a good storage phase change thermal function. Due to the addition of phase change material, the single fiber strength of polyester was decreased and the elongation at break was improved slightly. The thermo-regulated polyester and polyester had the essentially the same moisture regain and hand feel.

Energy and exergy analysis of a switchable solar photovoltaic/thermal-phase change material system with thermal regulation strategies

The overheated photovoltaic (PV) panels during the late experimental period and severe temperature stratification of the phase change materials (PCMs) are critical factors influencing the photovoltaic/thermal-PCM system efficiency. In this work, an outdoor experimental switchable PV/T-PCM system coupled with copper fins and flexible thermal regulation strategies was investigated to maximize the energy conversion efficiency. The effect of different fin heights on the efficiency of the PV-PCM system without water flow was firstly investigated. Second, five cases under various thermal regulation strategies utilizing water flow were comprehensively investigated by the energy and exergy analysis. For the full-time regulation, both thermal energy and exergy efficiencies (ηth and Ex_th) increased when the water flow rate grew from 0.11 L/min (Case 2) to 2.92 L/min (Case 5). Case 5 presented the highest ηth and Ex_th of 86.49% and 2.06%, respectively, and increments of 4.40% and 4.35% in the electrical energy and exergy efficiencies, respectively, with the addition of PCMs. At the same water flow rate of 0.11 L/min, the electrical energy and exergy efficiencies in Case 6 increased by 11.46% and 11.35%, compared with Case 2, indicating that the intermittent regulation is more beneficial for improving the photoelectric efficiency of the PV/T-PCM system.

Using proportional-integral-derivative controllers and PCM and a new design of building air intake with five scenarios to present a multi-zone CAV-AHU for tackling high energy consumption

Meet the requirements of regulating temperature, humidity and fresh air inside the buildings is not cost-effective due to high energy consumption (EC). In this study, a control system based on proportional-integral-derivative (PID) controllers was installed for mixing the supply air and return air in two strategies including installing phase change material (PCM) and a new layout for air intake from the return air were introduced for a constant air volume air handling unit (CAV-AHU). Considering a setpoint of 25 °C, the reference CAV-AHU was devised by the summer multiple design months technique, and it was observed that it is not likely to satisfy the setpoint requirement all the time. The first strategy was implemented, and it was found that although the final energy consumption declined by 15.3%, indoor temperature distribution was not acceptable. To regulate the indoor temperature, five scenarios were defined in which the share of return air utilization was variable. Establish the first scenario in a system that uses PCM provides less energy consumption by 177 Wh/m2 and better internal temperature distribution. In the second, third and fourth scenarios, the final energy consumption was reduced by as much as 404, 638 and 905 Wh/m2. In the best-case scenario (fifth), not only energy consumption reduction of 1277 Wh/m2 (5.5% reduction) was achieved but also the setpoint requirement was met. The addition of PCM and the variable share of return air utilization let the designer to design a lower rated power CAV-AHU (by 33%), thus reducing the initial investment cost and, in addition, the final energy consumption of the modified CAV-AHU is lower by 20%.

Water evaporation inspired biomass-based PCM from daisy stem and paraffin for building temperature regulation

The addition of phase change materials (PCMs) to building wall can effectively regulate building temperature. However, the preparation of inexpensive, easily available, and environmentally friendly composite PCMs with high enthalpy is still a great challenge. Herein, inspired by water transportation and capillary evaporation of natural plants, we selected the widely distributed and economically available wild daisy stem as the raw material for the first time to prepare form-stable composite PCMs for building temperature regulation. A hierarchical porous skeleton material was prepared by high temperature carbonization and chemical modification of wild daisy stem, and then it was impregnated with paraffin to obtain a composite PCM. The results show that the chemical modification using ethanol creates a richer pore structure and increases the PCM loading amounts. The obtained composite PCM was thermally, chemically and cyclically stable with the phase change enthalpy and phase change temperature of 213.6 J/g and 40.1 °C, respectively. Finally, the composite was applied to the temperature regulation of buildings, the center temperature of the phase change model was 5.1 °C lower than that of the ordinary house, indicating the building with the addition of the as-prepared PCM to the walls had significant thermal buffering effect under a simulated light compared to ordinary building with rapid temperature change. Thus, the excellent storage capacity of this composite material gives it great potential for application in building temperature regulation.