Salt Hydrate Phase Change Materials Research Articles

Mutability of Nucleation Particles in Reactive Salt Hydrate Phase Change Materials.

Nucleation particles, solid phases dispersed throughout a medium to decrease the energy barrier for solidification or other reversible phase transitions, are generally selected on the basis of structural or interfacial energy considerations between the host phase and the solid phase that is crystallizing. However, the existence of chemical reactions between the nucleation particles and the host phase can obscure these underlying relationships, thereby complicating the process of selection of active nucleation particle phases. Here, we reveal the origin of nucleation activity of barium-based nucleation particles in the salt hydrate calcium chloride hexahydrate (CCH), a candidate for near room temperature thermal energy storage. We demonstrate that these compounds undergo a series of cation exchange and secondary precipitation reactions, resulting in an assemblage of solid precipitates with some degree of limited solid solution, which collectively dramatically reduce undercooling in CCH, but which obscure the identification of a single crystalline phase primarily responsible for the nucleation of crystalline CCH from the liquid. Importantly, this result illustrates a pathway to harness in situ chemical reactions to generate stable active nucleation particles in reactive phase change materials, which may not be readily synthesized by alternative methods, or which may not be active or remain stable when added in isolation.

Experimental investigation of tailoring functionalized carbon-based nano additives infused phase change material for enhanced thermal energy storage

The advancement of phase change materials (PCMs) as potential thermal energy storage (TES) materials for building envelopes holds promise for efficient energy utilization. However, the PCMs have a major drawback during energy storage, which is lower thermal conductivity, leading to inadequate heat transfer performance and energy storage density. The foremost objective is to formulate a nanocomposite by dispersing functionalized multi-walled carbon nanotubes in salt hydrate PCM with the presence of surfactant. A two-step technique is employed to formulate the nanocomposites with different weight concentrations (0.2, 0.4, 0.6 and 0.8 %) of carbon-based nanoparticles and these nanocomposites are thoroughly characterized to explore the thermophysical properties. Resulting the nanocomposite demonstrates a significant improvement in thermal conductivity, increasing by 91.45 %, which can be attributed to the well-developed thermal networks with the PCM matrix. The nanocomposite samples exhibit extreme thermal stability up to 477 °C with a slight enhancement of 4.6 %. Optical investigations further confirmed that the transmissibility of PCM decreased to 8.3 % from 62.8 %, indicating an enhanced absorption capability due to the dark color nature of the nanoparticles. Moreover, the formulated nanocomposite demonstrated both chemical and thermal stability, with negligible changes in melting enthalpy even after 300 cycles of heating and cooling operations. Additionally, a numerical simulation analysis of 2D heat transfer was performed using Energy 2D software to demonstrate the efficacy of thermal conductivity in heat transfer. The thermally energized nanocomposite is suitable for medium-temperature TES applications such as photovoltaic thermal systems, building applications, textiles, electronic cooling, and desalination systems.

Critical analysis of enhanced photovoltaic thermal systems: a comparative experimental study of PCM, TEG, and nanofluid applications

Phase change materials (PCM), thermoelectric generators (TEG), and nanofluids are popular methods investigated for improving conventional photovoltaic thermal (PVT) systems. These methods are particularly used in warm climates where high temperatures negatively impact photovoltaic (PV) power output and energy efficiency. This experimental study evaluated the effects of 32 °C melting point PCM and TEG integration on PVT units, as well as 42 °C melting point PCM and nanofluid incorporation on concentrated PVT (CPVT) units. Technical, exergetic, and economic performance were compared using a small-scale PVT module. Low-cost commercially available materials were used to construct all PVT units. Industrial metal waste was introduced to enhance the thermal conductivity of paraffin wax and salt hydrate PCMs. The results indicated that applying PCMs, porous media, and concentrator plates increased energy generation, potentially offsetting their higher initial cost and achieving an energy cost of approximately $0.135/kWh. However, TEG and nanofluid implementation remained uneconomical, leading to a 15–35 % increase in energy cost. The water-based CPVT unit, enhanced with paraffin wax and copper fins, demonstrated the best technical performance. This unit achieved electrical, thermal, and exergy efficiencies of approximately 15.5 %, 37.4 %, and 16.7 %, respectively, with more than a 20 % reduction in cell temperature. The study also revealed that severe structural changes caused by corrosion of metallic materials in hydrated PCMs could alter the melting point by more than 30 %. This change negatively impacts heat storage capacity. Conversely, incorporating metal chips in non-hydrated PCMs improved the time to reach the melting point state by 30–60 minutes.

Preparation and investigation of a prefabricated salt hydrate phase change material partition for passive solar buildings

The incorporation of phase change material (PCM) into building structures offers a pathway for passive energy storage, enabling adaptable indoor temperature control and alleviating energy consumption. Despite these advantages, the widespread adoption of PCM in building structures faces challenges due to extended payback periods. In this study, a novel and cost-effective salt hydrate PCM composite, comprised of calcium chloride hexahydrate–potassium chloride (CCH–KCl), was developed. Melamine foam (MF) and strontium chloride hexahydrate (SCH) were synergistically utilized to address phase separation and supercooling issues. Numerical simulations were conducted to assess the performance of the developed salt hydrate PCM composite in building partition walls. Specifically, incorporating a 20 mm-thick composite resulted in peak temperature reductions of 0.72 °C during normal operation and 1.01 °C during power outages compared to structures without PCM, accompanied by a substantial reduction in energy consumption by 5376.68 kWh/year. Moreover, the cost of the developed salt hydrate PCM is 89.33 % lower than industrial paraffin, and it reduces CO2 emissions by 1.40 kg/year/m2 compared to paraffin's 1.11 kg/year/m2. In summary, the developed salt hydrate PCM composite exhibits commendable thermal regulation and economic advantages in building applications, serving as a pivotal contributor to emission reduction efforts.

Evolving Thermal Energy Storage Using Hybrid Nanoparticle: An Experimental Investigation on Salt Hydrate Phase Change Materials for Greener Future

Thermal energy storage (TES) assisted with phase change materials (PCM)s seeks greater attention to bridge the gap between energy demand and supply. PCM has its footprint toward efficient storage of solar energy. Inorganic salt hydrate PCMs are propitious over organic PCMs in terms of energy storage ability, thermal conductivity, and fireproof, however the major issue of supercooling and poor optical absorbance remains. This research investigates commercialized inorganic salt hydrate PCM with phase transition temperature of 50 °C, thermal conductivity of 0.593 W m−1 K which is favoured with melting enthalpy of 190 J g−1, and 2–3 °C of supercooling. Mixture of graphene: silver at a proportion of (1:1) is used as the hybrid nanomaterial to further enhance the thermal conductivity, optical absorbance, and thermal stability. Hybrid nanocomposites are developed via two‐step process involving direct mixing and ultrasonication. Morphological behaviour, chemical stability, optical property, thermal property, thermal reliability, and stability of the developed nanocomposite samples are experimentally analysed. As a result, sustainable TES materials with thermal conductivity of 0.937 W m−1 K, optical absorbance of 0.8, increased energy storage potential is formulated. Subsequently a numerical simulation is conducted to illustrate the potential of the developed nanocomposite in transfer of heat energy.

Experimental investigation on the performance of binary carbon-based nano-enhanced inorganic phase change materials for thermal energy storage applications

Phase change materials (PCMs) are considered potential resources for Thermal energy storage (TES) applications. However, the PCMs are limited because of their lower thermal conductivity, resulting in a significant decrease in heat transport and energy storage capability. The foremost objective of the present research is to formulate a novel salt hydrate PCM filled with binary carbon-based nanoparticles (graphene and multi-walled carbon nanotubes) at various weight concentrations and examine the thermophysical properties. A two-step approach is used to formulate binary nanomaterials dispersed salt hydrate PCM. The formulated binary nanocomposite's thermo-physical properties like morphological behaviour, thermal stability, chemical stability, melting enthalpy, optical performance, rate of heat transfer and thermal reliability were characterized. The binary nanoparticle-enhanced nanocomposites can form a decent thermal network, resulting in a remarkable enhancement in thermal conductivity by 160 % (1.2 W/mK) compared to pure salt hydrate. Moreover, a remarkable improvement in optical absorptance and a reduction in optical transmittance by 82.55 % for 0.7 wt% graphene and 0.07 wt% MWCNT enhanced salt hydrate PCM (SAHGrM-0.07) than pure salt hydrate PCM. In addition, the formulated nanocomposites possess excellent heat storage capability, chemical and thermal stability after 300-thermal cycling. The binary carbon-based nanoparticle-enhanced salt hydrate nanocomposites offered acceptable thermal and chemical stability, thermal reliability, and heat transmission characteristics, by this means reflecting its appropriateness for medium-temperature solar TES applications.

High Power Density Thermal Energy Storage With Phase Change Material in Enhanced Compact Heat Exchangers

Abstract Performance of a novel ultracompact thermal energy storage (TES) heat exchanger, designed as a microchannel finned-tube exchanger is presented. With water as the heating–cooling fluid in the microchannels, a salt hydrate phase change material (PCM), lithium nitrate trihydrate (LiNO3 · 3H2O), was encased on the fin side. To establish the hypothesis that small-length-scale encasement (<3 mm) of PCM substantially enhances heat transfer to yield very high power-density energy storage, heat exchanger designs with 10 and 24 fins/inch were considered. They were subjected to thermal cycling, or repeated heating (melting) and cooling (freezing), with inlet fluid flow mimicking diurnal variation between 42 °C and 25 °C (representing typical arid-region conditions) over an accelerated time period. By employing salt self-seeding to obviate subcooling during cooling or recrystallization, the TES was found to exhibit stable long-term (100 heating–cooling cycles) operation with very high PCM-side heat transfer coefficients (∼100–500 W/m2 K) and storage power density (∼160–175 kW/m3). In fact, with optimization of heating–cooling fluid flowrate for given charging–discharging time period and exchanger size, power density >300 kW/m3 can be achieved. The results clearly establish that highly compact heat exchangers used as TES units can provide very high-performance alternatives to conventional ones.

Preparation, characterisation and property modification of a calcium chloride hexahydrate phase change material slurry with additives for thermal energy transportation

Efficient thermal energy distribution and rational energy management are effective solutions to address the significant and fast-ascending energy consumption in building heating, ventilation, and air conditioning (HVAC). Phase change material (PCM) slurries with excellent thermal energy transportation and storage characteristics have been recognised as promising secondary refrigerants to simultaneously facilitate efficient heat/cold transport and effective thermal energy storage in air conditioning systems. Among various PCM slurries, salt hydrate PCM slurries have attracted increasing attention in recent years due to their many inherent advantages. This paper presented the preparation, characterisation, and property modification of a CaCl2·6H2O slurry based on a methodology proposed for optimal salt hydrate PCM slurry development. Theoretical modelling was first carried out to assess the availability of salt hydrate PCM slurries based on the phase diagram and solid fraction, followed by a series of property measurements to reveal the mechanisms and address the problems behind the phase transition, crystal particle morphology, stability and rheologic characteristics, using nucleating agents, surfactants and stabilisers. It was found that the salt hydrate PCM slurry developed provides a unit volume enthalpy twice that of water over the phase change temperature range of 5°C, together with acceptable fluidity. The results also showed that the PCM particle size can be well controlled, and the slurry can be stabilised, with the assistance of surfactants and stabilisers. Compared to other types of PCM slurries, the proposed salt hydrate PCM slurry has the advantages of being cost-effectiveness, easy preparation, adjustable phase change temperature, etc., which is promising to facilitate energy saving and rationalisation in building HVAC.

Influence of metal encapsulation on thermophysical properties and heat transfer in salt hydrate phase change material for air conditioning system

Phase change materials (PCM) are gaining increasing attention as a cold energy storage technology for air conditioning systems due to their potential to reduce electrical grid loading, energy consumption, and electricity costs. However, realizing the full potential of PCM-based cold energy storage in practical applications is constrained by low cold energy transfer efficiency within air conditioning systems. This study addresses this challenge by exploring the encapsulation of salt hydrate PCM using six different metals to enhance heat transfer efficiency. Additionally, the corrosion behaviors of the PCM towards these metals were thoroughly evaluated. Notably, copper demonstrated the highest corrosion rate, and the resulting corrosion products, particularly from copper and brass, were found to substantially reduce the energy storage capacity of PCM. Moreover, PCM encapsulated into aluminum alloy exhibited higher heat transfer efficiency than that of stainless steel. In light of these findings, aluminum alloy is recommended as the optimal choice for PCM encapsulation, given its corrosion resistance and minimal effect on thermal properties. This research provides crucial insights for selecting appropriate metals to enhance the efficiency and durability of air conditioning systems utilizing salt hydrate PCM.

Advancements and challenges in enhancing salt hydrate phase change materials for building energy storage: Optimization methodologies and mechanisms

Advancements and challenges in enhancing salt hydrate phase change materials for building energy storage: Optimization methodologies and mechanisms

Experimental investigation on nucleating agent for low temperature binary eutectic salt hydrate phase change material

The melting enthalpy and melting temperature have a significant impact on the latent heat that results from phase change materials (PCMs) used for thermal energy storage. Among the PCMs that are currently on the market, inorganic salt hydrates have greater thermal conductivity and latent heat than organic PCMs. However, the problem of salt hydrates' degree of supercooling limits their use in energy storage devices. Using sodium carbonate decahydrate (SCD) and sodium phosphate dibasic dodecahydrate (SPDD), a low temperature inorganic-inorganic eutectic salt hydrate PCM with a higher melting enthalpy and intended phase transition temperature is developed in this research study. The eutectic SCD/SPDD salt hydrate PCM eutectic point and the eutectic composition of salt hydrate PCMs to operate at low temperature range is numerically determined using Schrader equation. By numerical methods we obtain the 68 wt% of SCD with 32 wt% of SPDD to exhibit eutectic SCD/SPDD composite with eutectic melting temperature of 26.2 °C and melting enthalpy of 210.6 J/g. The synthesised eutectic PCM are characterised to explore their chemical stability, latent heat, melting point and their shortcoming due to degree of supercooling. A good way to get around the problem of the supercooling degree is to disperse the nucleating agents. In order to assess the type and degree of supercooling, the produced eutectic PCM composition is experimentally evaluated at 1–10% utilising borax, alumina, and sodium sulphate dodecahydrate as nucleating agents. However, for building cooling applications PCM with minimal degree of supercooling, with the ability to release low enthalpy during discharging is an advantage.

Microcapsule fabrication by ATRP at the interface of non-aqueous emulsions.

We present soft-template encapsulation of salt hydrate phase change materials (PCMs) using modified silica particles to both stabilize emulsions and serve as initiators for organocatalyzed photoredox ATRP. The resulting core-shell structures have high core loading and are robust to thermal cycling. Critically, this strategy eliminates the need for a reagent in the core phase, thus preserving purity, and offers the ability to tailor shell composition for desired applications.

Hydrogel-stabilized supercooled salt hydrates for seasonal storage and controlled release of solar-thermal energy

Seasonal storage of solar-thermal energy within salt hydrate phase change materials (PCMs), which are known for their large latent heat capacity, suitable phase change temperature range and cost-effectiveness, has garnered...

Energizing the Thermal Conductivity and Optical Performance of Salt Hydrate Phase Change Material Using Copper (II) Oxide Nano Additives for Sustainable Thermal Energy Storage

Due to intermittent nature of solar energy, scientists and researchers are working to develop thermal energy storage (TES) systems for effectively use the solar energy. One promising avenue involves utilizing phase change materials (PCMs), but primary challenge lies in their limited thermal conductivity, which results in slower heat transfer rate and lower thermal energy storage density. The present research work demonstrates, to develop and explore a PCM composite by embedding salt hydrate and coper (II) oxide to enhance the heat transfer mechanism for potential utilization of TES material. The optical behavior, and thermal conductivity were analyzed by using Ultraviolet visible spectrum, and thermal property analyzer. The developed copper oxide dispersed PCM composite displayed the thermal conductivity was energized up to 71.5 % without affecting the other properties. Also, the optical absorptance was remarkably enhanced and the transmittance reduced to 87 %. Increasing the concentration of copper oxide nanoparticles in the salt hydrate PCM improves the optical absorptivity and heat conductivity. With these extraordinary abilities the nanocomposite could play a significant role in progress of sustainable TES with significance to contribute towards sustainable development goal of affordable and clean energy and climate change.

Energizing eutectic salt hydrate phase change material using 2D carbon based graphene nanoparticle

Energy being the strongly depended source for development and industrialization, their storage in any form tends to bridge the gap between demand and supply. Renewable energy technology systems now include energy storage as a crucial component. Thermal energy storage is a technique that stores thermal energy by heating or cooling a storage medium. This allows the energy to be used for heating and cooling purposes later on. The present study develops ternary inorganic salt hydrate eutectic phase change material (EPCM) that is intended for cooling buildings. Melting temperature, melting enthalpy and eutectic composition proportion of inorganic salt hydrate of sodium carbonate decahydrate (SCD), sodium phosphate dibasic dodecahydrate (SPDD), and sodium sulphate decahydrate (SSD) are determined using the eutectic melting point theory. Ternary EPCM is synthesised experimentally in accordance with the percentage of salt hydrates. Graphene nanoplatelets are distributed at different weight concentrations of 0.3%, 0.6%, and 0.9% in order to further improve the thermal performance; at higher concentration above 0.9% the graphene nanoplatelets tends to agglomerate. In order to assess the chemical stability and thermal properties of prepared nanoparticle dispersed PCMs, are experimentally assessed. Findings confirm the ternary EPCM's chemical stability and raise its latent heat with graphene nanoplatelets.

Smoothing cooling demand of buildings with PCM thermal batteries

Escalating energy tariffs and peak cooling demands due to climate change along with expanding use of variable renewable energy supply are presenting new challenges and opportunities for air conditioning system operation and control. This research presents the outcome of an investigation into the use of a thermal battery using salt-hydrate phase change material (PCM) in commercial buildings. A 1.2 m3 modular thermal battery using 15 °C melting temperature salt-hydrate PCM has been designed and fabricated. Its cooling performance and feasibility of integration into a chilled water-cooling system of commercial buildings has been comprehensively investigated. This storage unit can accommodate approximately 52 kWh of energy, featuring a rapid heat discharge rate of 32.58 kW during the initial 30 min to effectively address sudden cooling demands. The overall heat discharge rate closely aligns with simulation results, reaching approximately 96% accuracy. This has been achieved through optimisation of the heat exchanger design through mathematical simulation, detailed testing to match various operational scenarios and evaluation of economic and peak load shifting benefits. The results demonstrate the environmental and economic effectiveness of the PCM thermal battery as an independent component in building cooling systems. It provides a timely response to peak cooling demand and improves thermal comfort of the buildings.

MXene-based eutectic salt hydrate phase change material for efficient thermal features, corrosion resistance & photo-thermal energy conversion

Salt hydrate phase change materials (PCMs) possess low thermal conductivity, degree of supercooling, lack of corrosion resistance and poor photo thermal conversion ability. To overcome these challenges, a two dimensional, chemically stable, optically & thermally efficient MXene@eutectic salt hydrate composite PCM is developed for effective harnessing of solar energy and thermal energy storage (TES) applications. Low temperature eutectic salt hydrate PCM with phase transition temperature of 27.6 °C and 216 J/g melting enthalpy is developed using sodium sulphate decahydrate (SSD) and sodium phosphate dibasic dodecahydrate (SPDD) based on Schrader equation. Advanced 2D layered material, MXene (Ti3C2) is synthesised from MAX phase (Ti3AlC2). Furthermore, MXene based PCM nanocomposite is developed with binary eutectic PCM of SSD/SPDD at different weight fractions through two step technique. Developed nanocomposite PCM exhibits better chemical stability, high optical absorbance of (1.1), low transmissibility (10.2 %), reliable thermal conductivity (0.621 W/m⋅K), improved melting enthalpy (161.2 J/g) and considerable cycle stability. The optical absorbance and thermal conductivity demonstrated a superior photo-thermal conversion capability and thermal networks for the developed MXene based composite sample at 0.9 wt% of MXene. The above properties are experimentally inferred by evaluating the developed MXene@ eutectic salt hydrate and base eutectic PCM under the solar simulator. The interfacial attraction between the two dimensional MXene nano flakes and the developed eutectic PCM ensures a promising ability to trap solar energy effectively for thermal regulation in a sustainable direction. Subsequently, the effect of MXene with SSD/SPDD in regard to the issue of corrosion is explored for copper and aluminium metal surface.

Hybrid Polymer Salogels for Reversible Entrapment of Salt-Hydrate-Based Thermal Energy Storage Materials.

One of the challenges preventing wide use of inorganic salt hydrate phase change materials (PCMs) is their low viscosity above their melting point, leading to leakage, phase segregation, and separation from heat exchanger surfaces in thermal management applications. The development of a broad strategy for using polymers that provide tunable, temperature-reversible shape stabilization of a variety of salt hydrates by using the lowest possible polymer concentrations is hindered by differences in solubility and gelation behavior of polymers with change in the type of ion. This work addressed the challenge of creating robust, temperature-responsive shape-stabilizing polymer gels (i.e., salogels) using a low cost PCM, calcium chloride hexahydrate (CaCl2·6H2O, CCH). Due to the extremely high (9 M) concentration of chloride ions and the tendency to salting-out polymer chains, the previous strategy of using single-polymer salogels was not successful. Thus, this work introduced a strategy of using two polymers, poly(vinyl alcohol) and ultrahigh molecular weight polyacrylamide (PVA and PAAm, respectively), along with borax as a cross-linker to achieve temperature-reversible, shape-stable salogels. This system resulted in robust salogels whose gel-to-sol transition temperature (Tgel) was tunable within an application-relevant range of gelation temperature (30-80 °C). This behavior was enabled by a synergistic combination of dynamic covalent cross-links between PVA units and entanglements of PAAm chains which were combined into a single hybrid network. The hybrid salogels had <5 wt % polymer content, maintaining ∼95% of the heat of fusion of the pure PCM. Importantly, the noncovalent nature of gelation supported thermo-reversibility of gelation, shape stability, and retention of thermal properties over 50 melting/crystallization cycles.

Investigation of Thermal Performance and Chemical Stability of Metal Infused Salt Hydrate Phase Change Material for Thermal Energy Storage

Thermal energy storage (TES) is a technique that is considered a very desirable technology with a high potential to overcome the gap between demand and supply. Phase change materials (PCMs) are considered to be a highly favourable thermal energy storage materials. Besides that, PCM has certain drawbacks, such as lower thermal conductivity and higher light transmission; owing to this, the heat transfer rate and energy storage density are less. The performance of the PCMs can be improved by adding highly conductive nanoparticles. In this study, various weight percentages (0.1% - 5.0%) of Copper (II) oxide nanoparticles are dispersed with salt hydrate phase change materials with melting temperature 50 °C and investigated the thermal and chemical properties using Thermogravimetric analyzer, thermal conductivity analyzer, and Fourier transform infrared spectrum. Results shows that the prepared nanocomposites have chemically and thermally stable up to 467 °C. The thermal conductivity was increased by 62.64%, at 3.0 wt% Copper (II) oxide with salt hydrate PCM. The developed nanocomposites have better thermophysical properties than pure salt hydrate, which may be applied for TES applications like solar water heating, photovoltaic thermal systems, and electronic cooling systems.

Optical performance and chemical stability evaluation of new era phase change material: Activated by hybrid nanoparticle

Inorganic salt hydrate phase change materials (PCMs) are ahead of organic PCMs in terms of energy storage ability and safety as they are non-flammable. However the major hindrance with inorganic PCM are degree of supercooling and low thermal conductivity though better than organic PCM. The common technique to enhance the thermal conductivity is via dispersion of metal and carbon nanoparticle. Though they enhance the thermal conductivity of the nanocomposite, with continuous operation the nanoparticle agglomerate and settles down owing to their density. Henceforth, in the current research work we conduct an experimental investigation to enhance the optical and thermal performance of commercialised inorganic salt hydrate PCM using metal-carbon hybrid nanoparticle. We disperse graphene silver nanoparticle at different weight ratio adopting a two-step method followed by probe sonication to ensure uniform dispersion. We achieve a highly stable nanocomposite with 584% increase in optical absorbance of electromagnetic waves and 86% decrease in transmittance. Thermal management of electronic gadgets has evolved to be a major consideration of research as overuse of gadgets lead to rapid temperature rise and is in need of passive cooling system. Henceforth the newly developed nanocomposite phase change materials (PCMs) not only acts as thermal batteries but can also be opted as energy materials for thermal regulation and heat mitigation.