Supercooling Stability Research Articles

Controllable heat release of supercooled Erythritol-based phase change materials for long-term thermal energy storage

Transeasonal heat storage in organic phase change materials (PCMs) present a promising solution to the intermittent nature of renewable energy. However, PCMs are prone to spontaneous crystallization during storage, leading to the loss of stored latent heat in low-temperature environments. In this study, we incorporated tetrasodium ethylenediaminetetraacetic acid (EDTA-4Na) and superabsorbent polymer (SAP) to erythritol (ERY), referred to as EES-PCMs, to overcome these challenges and achieve more controllable and stable thermal energy storage. The incorporation of EDTA-4Na and SAP into ERY significantly improves the supercooling stability and phase change enthalpy. The optimal ratio (EES-PCMs-2) of phase change enthalpy reaches an impressive 286.62 J/g, with stable performance maintained for 120 days at room temperature. The EES-PCMs-2 exhibits exceptional thermal cycling stability, retaining its properties even after 100 cycles. A novel air-triggered crystallization method is demonstrated, enabling a temperature increase from room temperature to 48.21 °C in 320 s after being exposed to air for long-term storage. This innovative approach effectively overcomes the limitations of traditional triggering mechanisms, providing a straightforward and efficient method for thermal management. The high thermal storage capacity, stability, and controlled exothermic properties of EES-PCMs position them as promising candidates for applications in seasonal solar thermal energy storage.

Effect of salt-induced supercooling stability on the quality of chicken breast during supercooled storage

The effect of salt on the stability and quality of fresh chicken breast meat during supercooling preservation was investigated. The results showed that 0.75% salt kept the non-frozen state of chicken breast at −3 °C for 12 days. Compared to storage at −1 °C, storing at −3 °C could further extend the shelf life of chicken, but there was a risk of freezing the chicken meat (31% frozen after 4 d and all after 8 d). Microstructure images revealed that muscle fibers in the −3 °C samples were destroyed by crystallization, whereas ice nucleation was not observed in the −3 °C + salt treatment. The drip loss and centrifuging loss of the −3 °C + salt group after 12 days of storage (1.48%, 20.10%) were significantly lower than those of the −1 °C group (4.14%, 24.49%), the −3 °C group (8.37%, 27.47%), and the −1 °C + salt group (1.99%, 22.60%). Low-field nuclear magnetic resonance results showed that water migration in chicken breast was inhibited with −3 °C + salt treatment. Overall, the good quality of chicken breast was maintained by −3 °C + salt. The results provide a theoretical basis for industrial application of supercooling preservation of chicken.

Experimental investigation on triggering solidification of supercooled sodium acetate trihydrate with extra water and different thickening agents by local cooling

Addition of extra water or thickening agents can reduce the phase segregation of salt hydrate phase change materials, but may influence the supercooling stability and crystallization of the mixture solution for supercooled thermal storage. Triggering solidification of supercooled sodium acetate trihydrate (SAT) is experimentally investigated by local cooling method (using a 72 W semiconductor refrigerator) with the addition of extra water as well as 7 thickening agents, i.e. carboxymethyl cellulose (CMC), gelatin, urea, starch, polyvinyl alcohol (PVA), polyacrylamide (PAM) and xanthan gum (XG). The water content in SAT water solution ranges from 40.01 % (only crystal water content, no extra water) to 50 % (9.99 % extra water). The mass ratio of thickening agents to SAT is between 0.25 % and 3 %. The results show that 44 % water content SAT solution can effectively alleviate the phase segregation and also has relatively short induction period for crystallization initialization with the discharging temperature as high as 51.8 °C. Among the 7 thickening agents, gelatin, CMC, starch and XG present better performances than urea, PVA and PAM for alleviation of phase segregation. Each additive has its suitable mass proportion considering the triggering and discharging performances. With the same local cooling power of 72 W, SAT samples containing 1 % gelatin present the highest discharging temperature (Tdis) of 55.8 °C as well as shorter induction period (τin) of 1.1 min; 2 % CMC samples have the discharging temperature as high as 55 °C and induction period of 11 min; the amount of starch has slight effect on triggering performances and the relatively better proportion is 0.25 % with Tdis = 52 °C and τin = 1.6 min; the suitable XG content is 0.5 % with Tdis = 49.2 °C and τin = 7.3 min under present conditions. The obtained results are helpful in selecting SAT additives for phase segregation reduction, better triggering and discharging performances based on supercooled thermal storage.

Relating Metabolism Suppression and Nucleation Probability During Supercooled Biopreservation.

Aqueous supercooling provides a method by which to preserve biological matter at subfreezing temperatures without the deleterious effects of ice formation. The extended longevity of the preserved biologic is a direct result of a reduction in the rate of metabolism with decreasing temperature. However, because the nucleation of ice from a supercooled solution is a stochastic process, supercooled preservation carries the risk of random ice nucleation. Theoretical supercooled biopreservation research to date has largely treated these biological and thermophysical phenomena separately. Here, we apply a statistical model of stochastic ice nucleation to demonstrate how the possible reduction in metabolic rate is inherently related to supercooling stability (i.e., the likelihood of ice nucleation). We develop a quantitative approach by which to weigh supercooling stability versus potential metabolic reduction, and further show how the stability-metabolism relationship varies with system size for two assumed modes of nucleation. Ultimately, this study presents a generalizable framework for the informed design of supercooled biopreservation protocols that considers both phase transformation kinetics and biochemical or biophysical kinetics.

Methods to stabilize aqueous supercooling identified by use of an isochoric nucleation detection (INDe) device

Stable aqueous supercooling has shown significant potential as a technique for human tissue preservation, food cold storage, conservation biology, and beyond, but its stochastic nature has made its translation outside the laboratory difficult. In this work, we present an isochoric nucleation detection (INDe) platform for automated, high-throughput characterization of aqueous supercooling at >1 mL volumes, which enables statistically-powerful determination of the temperatures and time periods for which supercooling in a given aqueous system will remain stable. We employ the INDe to investigate the effects of thermodynamic, surface, and chemical parameters on aqueous supercooling, and demonstrate that various simple system modifications can significantly enhance supercooling stability, including isochoric (constant-volume) confinement, hydrophobic container walls, and the addition of even mild concentrations of solute. Finally, in order to enable informed design of stable supercooled biopreservation protocols, we apply a statistical model to estimate stable supercooling durations as a function of temperature and solution chemistry, producing proof-of-concept supercooling stability maps for four common cryoprotective solutes.

Effects of an oscillating magnetic field on ice nucleation in aqueous iron‐oxide nanoparticle dispersions during supercooling and preservation of beef as a food application

AbstractThis study was aimed to explore the effects of an oscillating magnetic field (OMF) on the ice nucleation behavior of distilled water (DW) and iron‐oxide nanoparticle dispersion (IND) during supercooling. The magnetic field intensity and distribution of the OMF produced by Helmholtz coils were predicted using COMSOL. It was hypothesized that the ferric nanoparticles in the IND would promote the heterogeneous ice nucleation, and the OMF could inhibit the nucleation process by rotating the particles. The supercooling probability of IND was significantly increased by 36% under the OMF at the ambient temperature of −10°C. However, the OMF also enhanced the supercooling stability of DW by 32%, suggesting that it could induce the dipolar movements of water molecules via water diamagnetism and create the induced electric fields, subsequently suppressing the occurrence of ice nucleation within DW as well. As an extended application, fresh beef was preserved in a supercooled state with the OMF treatment and its supercooled state was effectively extended for a week at the temperature of −4°C. The supercooling preservation potentially prolonged the shelf life of meat with no significant changes in drip loss, color, and bacterial growth for up to a week in this study.Practical applicationsRecently, the application of an oscillating magnetic field (OMF) has attracted considerable interest in the food preservation industry because the OMF is supposed to control ice nucleation during the freezing process. The present study demonstrated that the OMF treatment potentially suppressed ice nucleation in water and aqueous iron‐oxide nanoparticle dispersion. As a case study, beef steaks were preserved at subzero temperatures with the OMF treatment and they were successfully supercooled at −4°C for up to 7 days. The supercooling technology based on the OMF allowed to maintain the meat quality for an extended period while preventing bacterial growth. This novel technology can be integrated into a commercial refrigeration system and ensure the prolonged shelf life of various food products.

Demonstration of Mg(NO3)2·6H2O-based composite phase change material for practical-scale medium-low temperature thermal energy storage

This work focuses on the industrialization-oriented investigation of a latent heat storage using a magnesium nitrate hydrate-based composite phase change material. Three aspects of studies are included: (i) characterizations on the thermal-physical properties of the composite, (ii) explorations on the supercooling stability of the composite within continuous thermal cycles, and (iii) evaluations on the thermal performance of a pilot-scale storage unit. The results indicate that the freshly-prepared composite has a fusion heat of 147.9 ± 0.5 J g−1, a storage capacity of 253.5 ± 0.9 J g−1 within 70–110 °C. The PCM presents no significant degradation after 100 thermal cycles. The material performs a better supercooling stability than pure magnesium nitrate hexahydrate. The designed latent heat storage unit can achieve stable charges and discharges with an effective heat storage density of 33.5 ± 2.6 kWh m−3, a thermal efficiency of 88.1 ± 9.6% and a thermal loss of around 10% during a daily operation. In addition, the storage unit performs a higher latent heat release concentration as discharging rate drops and its effective storage capacity within 80–85 °C is over 4.3 times of water storage. Thedensity of the device within a daily operation can be effectively improved by reducing the thickness of thermal insulation layer.

Surface free energy analysis for stable supercooling of sodium thiosulfate pentahydrate with microcosmic-visualized methods

A novel method of microcosmic-visualizing was employed in investigating the supercooling stability of a phase change material (PCM). The supercooling behavior of the PCM under circumstances of different surface free energy was studied both dynamically and statically, and a theory analysis of how the surface free energy of the substrate affects the stable supercooling of PCM was carried out. The results showed that, the PCM droplets phase changed after a 20-cm free fall on substrate with larger surface free energy, while remained supercooled on substrate with lower surface free energy. The PCM in PTFE container initiated crystallization at −8.99 °C, withstood over 400% on hours at liquid state compared with the sample in glass container, while a large supercooling degree of over 57 °C was achieved. It indicated that containers made of materials with lower surface free energy could be considerably beneficial in stabilizing supercooling of PCMs, which could give a guide to the practical application on long-term energy storage of PCMs. What is more, the surface free energy theory also works on the air-liquid interface. The oil-covered PCM sample withstood a temperature of 5 °C for 10 months without crystalized in a refrigerator, showing great potential on supercooling stabilization.

Crystallization by local cooling of supercooled sodium acetate trihydrate composites for long-term heat storage

Sodium acetate trihydrate (SAT) can be used for long-term heat storage in buildings by utilizing its ability to supercool stably to ambient temperatures while preserving its heat of fusion. Additives are used to stabilize the SAT and avoid phase separation. A reliable method for initializing the solidification of supercooled SAT composites is needed to operate a heat storage unit based on supercooled SAT. The crystallization temperatures of SAT composites during cooling were therefore investigated and experiments carried out using methods applying local cooling in a small part of prototype heat storage units to initialize crystallization. To find the crystallization temperatures of SAT composites, supercooled samples were cooled down in a freezer. The influence of rusty metal parts submerged in melted SAT composite samples and various periods at rest in a supercooled state were investigated with regard to supercooling stability and crystallization temperature. Carboxymethyl cellulose, extra water, liquid polymer HD 310, metal-based graphite flakes, and silicone oil were applied as additives to form the different SAT compositions. Samples with 60 g SAT in glass jars were subject to repeated heating and cooling cycles. It was found that samples containing steel profiles crystallized in the range of − 9 to − 15 °C, while SA-water mixtures without steel profiles cooled down to − 24 °C before crystallizing. Furthermore, samples with carboxymethyl cellulose and liquid polymer HD 310 showed a greater temperature rise during crystallization, which is in accordance with previous findings on heat contents. SA-water mixtures showed a second minor temperature peak at temperatures below − 20 °C, when the sample was cooled down again after the first temperature rise. Devices were developed to initialize the crystallization of supercooled SAT composites in prototype heat storage units using rapid local cooling of the SAT composite. We successfully initialized crystallization by evaporating pressurized liquid carbon dioxide in a small chamber on one side of the PCM container and by using Peltier elements. Our experiments showed that the controlled initialization of crystallization by cooling is feasible for all the SAT composites investigated.

Relationship between supercooling stability and solution structure in sodium acetate aqueous solution

We have observed the solution structure of the supercooled sodium acetate aqueous solution, especially for the existence of clusters and their crystallization process, by means of Scanning electron microscopy (SEM) with the freeze replica method. Microscopic internal structure of sodium acetate trihydrate crystals mainly constitutes the aggregates of 100–200nm in diameter, which consists of the clusters of 10–20nm in diameter. In the case of a supercooled aqueous solution of 293K, two types of aspect in the vitrified aqueous solution mainly exist: one is the clusters of 10–20nm in diameter; the other is the smooth zone without any structure. At 263K, the relationship among clusters of 10–20nm and their aggregates of 100–200nm was clearly observed. The aggregates construct the three-dimensional loose networks, which are not fully packed, different from the crystal.

A Study of Water Supercooling

The objective of this paper is to investigate water supercooling. Supercooling occurs when a liquid does not freeze although its temperature is below its freezing point. In general, supercooling is an unstable condition and occurs under special conditions. The parameters that influence supercooling stability and probability of occurrence include freezer temperature and water’s initial temperature. In this paper, it is shown that with a freezer temperature range of -3℃ to -8℃, supercooling is most likely to happen and is independent of the water’s initial temperature. Furthermore, as the freezer temperature decreases, the probability of nucleation increases, causing instant freezing. Finally, it is concluded that the Mpemba effect, in which initially hot water freezes faster than initially cold water, is due to the supercooling instability in initially hot water in which nucleation agents are more active.

The structure of directionally solidified two-phase Sn-Cd peritectic alloys

The structure of Sn-Cd two-phase peritectic alloys directionally solidified at various values ofG/υ (temperature gradient in the liquid divided by growth rate) is reported. The minimum value of G/υ as a function of composition required for the solidification of two-phase peritectic alloys with a planar liquid-solid interface is estimated using a simple constitutional supercooling stability criterion. At a value ofG/υ just below this minimum value, these alloys solidify with a nonplanar interface consisting of cells of α (the high temperature phase) and intercellularβ (the low temperature phase). This produces a coarse rod-like microstructure consisting of rods of α phase imbedded in aβ matrix. At a value ofG/υ above this minimum value, these alloys solidify with a planar interface which alternately deposits bands of α andβ transverse to the growth direction. No coupled growth of α andβ at a planar interface is observed in Sn-Cd two-phase peritectic alloys as was expected. To understand this, an analysis of coupled (eutectic-like) growth of two-phase peritectic alloys is presented and contrasted with the results of the Jackson-Hunt theory of lamellar eutectic growth. This calculation indicates that the coupled growth of two-phase peritectic alloys is unlikely on theoretical grounds.