Phase Change Thermal Storage Research Articles

Enhancing the sustainability of interfacial evaporation to mitigate solar intermittency via phase change thermal storage

Solar-driven interfacial water evaporation is a low-carbon footprint strategy for addressing global water scarcity. However, the operation of the evaporator requires continuity of solar radiation. Herein, the key to overcoming the intermittency of sunlight lies in utilizing the heat storage/release cycle of phase change materials. Additionally, the synergistic effect of high thermal conductivity materials and increased heat transfer area addresses the nonuniform spatial temperature within the heat storage device caused by the low thermal conductivity of molten paraffin. Although the heat transferred to the paraffin reduces the evaporation rate under illumination, the thermal storage/release capacity of paraffin increases the evaporation mass by 171.5% in darkness. Ultimately, after one light–dark cycle, the total evaporation mass over the entire period increased by 11.5%. Finally, although paraffin undergoes sensible and latent heat absorption and release across various temperature ranges during multiple light–dark cycles and prolonged operation, the phase change delays at different internal locations still ensure stable dark-state evaporation compensation for the evaporator, thereby enhancing the sustainability of the evaporation process.

Experimental and numerical investigation on a hybrid high-temperature downhole thermal management system integrating liquid cooling and phase change material

The downhole electronics must operate in an extremely thermal environment for several hours. Previous researches have proved that passive thermal management systems (PTMSs) are able to protect downhole electronics over extended durations. However, conventional PTMSs commonly suffer from a significant thermal resistance between the electronics and phase change materials (PCM), which restricting the efficient heat transfer to the PCM and consequently reducing the effective operating time. In this study, a hybrid thermal management system (HTMS) integrating liquid cooling and phase change thermal energy storage technique was proposed to enhance the internal heat transfer performance of downhole electronics and extend the operation duration. An active heat transfer channel was established between the electronics and PCM through liquid cooling system, and thus the generated heat was efficiently transferred and stored in PCM. The thermal performance of the proposed HTMS was investigated both experimentally and numerically. The accuracy of the numerical model was validated through experimental results, with a deviation lower than 6 %. The experimental results show that the temperature difference between the heat source and the heat storage module (HSM) was reduced by up to 51.9 °C, and the workable time was increased by up to 166 mins compared to the system without liquid cooling. The proposed HTMS exhibits superior heat transfer performance, which contributes to achieving a longer effective operation duration and holds extensive and profound application prospects in the field of thermal management for downhole electronic devices.

Experimental and numerical investigations on phase change thermal storage foam concrete based on CaCl2∙6H2O/silica aerogel composite phase change material

A new type of phase change thermal storage foam concrete was developed by effectively incorporating a composite phase change material (CPCM) into foam concrete. The CPCM was obtained by using 75 wt% CaCl2∙6H2O as PCM and 25 wt% silica aerogel as carrier, with a phase change temperature of 27.0 °C and an enthalpy value of 110.9 J/g. The mechanical and thermal properties of the obtained phase change thermal storage foam concrete blocks were investigated experimentally, along with a numerical analysis of their heat transfer characteristics. The experimental results demonstrated that after adding CPCM, the thermal performances of foam concrete blocks significantly increased, under the condition of their dry densities and compressive strengths met the specification requirements. Adding 20 wt% CPCM, the enthalpy value, specific heat capacity, thermal conductivity and thermal inertia of foam concrete block respectively reached 37.0 J/g, 1782.0 J/(kg∙K), 0.131 W/(m·K) and 770.9, with appropriate phase change temperature (27.2 °C). Numerical analysis for the heat transfer characteristics of the phase change thermal storage foam concrete wall revealed that optimal thermal insulation and thermal storage performances were achieved when the wall contained 20 wt% CPCM and thickness of 80 mm. In this case, the model exhibited a temperature wave attenuation factor of 6.66, the temperature amplitude of 5.84 K and a decline of 9.87 K for the highest temperature of the wall as well as delay time of 198,000 s, effectively regulating indoor temperature and saving energy. Therefore, the as-prepared phase change thermal storage foam concrete had great potential for application in building energy conservation.

Scaling Law of Flow and Heat Transfer Characteristics in Turbulent Radiative Rayleigh-Bénard Convection of Optically Thick Media

Radiative natural convection is of vital importance in the process of energy storage, power generation, and thermal storage technology. As the attenuation coefficients of many heat transfer media in these fields are high enough to be considered as optically thick media, like nanofluids or molten salts in concentrated solar power or phase change thermal storage, Rosseland approximation is commonly used. In this paper, we delve into the impact of thermal radiation on the Rayleigh-Bénard (RB) convection. Theoretical analysis has been conducted by modifying the Grossmann-Lohse (GL) model. Based on turbulent dissipation theory, the corresponding scaling laws in four main regimes are proposed. Direct numerical simulation (DNS) was also performed, revealing that radiation exerts a notable influence on both flow and heat transfer, particularly on the formation of large-scale circulation. By comparing with DNS results, it is found that due to the presence of radiation, the modified Nu scaling law in small Pr range of the GL model is more suitable for predicting the transport characteristics of optical thick media with large Pr. The maximum deviation between the results of DNS and prediction model is about 10%, suggesting the summarized scaling law can effectively predict the Nu of radiative RB convection.

Black phosphorus modified wearable textile with excellent flame retardancy for personal thermal management and motion detection

A sandwich structure composite phase change textile material (CPCTM) was prepared by electrospinning. In the top and bottom layers, black phosphorus nanosheets (BPNs) was compounded into polyacrylonitrile (PAN). In the middle layer, the phase change thermal energy storage material polyethylene glycol (PEG) was well encapsulated by polyvinyl alcohol (PVA). By designing multilayer structure, the CPCTM exhibited excellent intensity with the tensile strength 62.65MPa and the elongation at break 1176%. The melting temperature and the crystallization temperature of CPCTM were 54.36 ℃ and 31.43 ℃ which were lower than pure PEG (55.87 ℃ and 35.55 ℃). The lower melting and crystallization temperature facilitated the storage of heat in CPCTM for body thermal management. Compared with that of pure PAN, the total heat release and total smoke production of the PAN@BP were respectively descended by 33.05% and 80.43%. During combustion, transfer of combustible gases and heat were hindered due to the formation of the expanded char layer by the BPNs. Meanwhile, the CPCTM showed excellent flexibility and ability of motion detection, which had broad application prospects in the fields of wearable electronic devices.

Efficiently all-weather anti-icing and de-icing coatings enabled by polyaniline microcapsules encapsulated phase change materials

Photothermal superhydrophobic coatings are one of the most promising anti-icing/de-icing materials. However, the intermittence of light energy limits the application of photothermal energy conversion technologies when continuous de-icing is required. Herein, an innovative solution for the integration of photothermal effect and phase change thermal storage was proposed. In this work, an efficient anti-icing/de-icing coating was successfully fabricated based on multifunctional polyaniline microcapsule encapsulating butyl stearate (BS). Benefiting from the heat storage capacity of BS in the microcapsule, the coating could achieve all-weather anti-icing capability. Under the condition of −20 °C, the freezing time of water droplets on the coating with only 10 wt% microcapsules was delayed by about 12.6 times compared to the blank coating. At the same time, under simulated dark conditions, the freezing time of water droplets could be delayed by about 14.1 times. Moreover, owing to the thermal conductivity and high solar energy exploitation, polyaniline endowed the coating with outstanding photothermal de-icing performance, presenting the superiority of outdoor applications. Under NIR (200 mW/cm2) illumination, the melting time of water droplets was reduced to 18 s, which was nearly 10 times faster than that on the blank coating. Moreover, the polyaniline microcapsules also possessed outstanding anticorrosion property, which was particularly attractive for mental coating applications. The combined properties of this all-weather anti-icing and de-icing coating could render it a promising contender for challenging outdoor applications.

Preparation of dodecahydrate disodium hydrogen phosphate shape-stabilized composite phase change materials and their experimental investigation in solar thermal storage and exothermic systems

To alleviate the mismatch between energy supply and demand caused by the spatial and temporal distribution mismatch and weather uncertainty during solar energy utilization, solar energy is combined with phase change thermal storage technology to improve the performance of solar thermal storage systems. In this study, a shape-stabilized composite phase change material with a highly absorbent resin structure is proposed as thermal storage material. This material exhibits a latent heat of phase change of 246.5 J/g, a thermal conductivity of 1.968 W/(m·K), and maintains good stability after 200 thermal cycles. Subsequently, a detachable experimental setup integrating solar energy with a phase change thermal storage tank was designed and constructed. The effects of inlet and outlet hot water flow rates and heat source temperature on heat storage time and the amount of stored water were investigated separately. The experiments show that increasing the heat source temperature during storage effectively shortens the storage time, and that the largest effective amount of hot water is obtained when the exothermic flow rate is 300 L/h. The study's results are significant for broadening solar energy utilization, alleviating the mismatch between solar energy supply and demand, and evaluating the thermal performance of latent heat storage systems.

Numerical Study of an Energy Storage Container with a Flat Plate Phase Change Unit Characterized by an S-Shaped Flow Channel

China’s rapid economic development and rising energy consumption have led to significant challenges in energy supply and demand. While wind and solar energy are clean alternatives, they do not always align with the varying energy needs across different times and regions. Concurrently, China produces substantial amounts of industrial waste heat annually. Effective recycling of this waste heat could substantially mitigate energy supply and demand issues. The Mobile Thermal Energy Storage (M-TES) system is a key solution to address these challenges, as it helps manage the uneven distribution of energy over time and space. This article establishes a packaged M-TES based on a plate-type phase change unit. Based on different placement methods of the plate-type phase change unit, different inlet temperatures and phase change temperature differences, and different inlet and outlet directions, the complete charging and discharging process of the packaged phase change thermal storage system was simulated using ANSYS FLUENT 2022 R1 software. The results showed that during the heating process of the entire system, the horizontal placement of the plate-type phase change unit and the inlet and outlet methods of the heat transfer fluid (HTF) significantly improved the heating effect of the system, increasing it by 15.9%. Increasing the temperature difference between the inlet temperature of the heat transfer fluid and the melting temperature of the phase change material (PCM) from 4 K to 19 K can increase the melting rate of PCM by approximately 54.9%

Modeling of Metal Matrix Concentrated Solar Receivers for sCO2 Power Blocks

Abstract Supercritical CO2 power blocks for Concentrating Solar Power (CSP) with novel metal matrix solar receivers have the potential to reduce operating expenses while improving overall system efficiencies. These concentrated solar receivers integrated with a metal matrix-based phase change (PCM) thermal storage medium provide the compounding effect of an efficient heat exchanger while also integrating thermal storage within the receiver. Detailed numerical modeling of such devices with enthalpy-porosity-based formulation for phase change and turbulent convective heat transfer for the sCO2 microchannels is described in the current work. With sCO2 power blocks operating at temperatures and pressures beyond 800°C and 200 bar, different high-temperature PCMs are studied. A detailed steady charging followed by discharge and charging transients is simulated to analyze the thermal performance of these devices. In the current work, the energy storage density of PCMs is studied, followed by an analysis of the movement of the melt-pool interface over the streamwise length of a high corrugation wavy microchannel. A scaling analysis is carried out to estimate the heat transfer coefficients while compare them with the numerical model predictions. The results from the current work can be utilized for sizing and detailed design of integrated solar receivers for high-temperature sCO2 power block applications.

Economic and life cycle analysis of a photovoltaic thermal application system based on phase change thermal storage

Based on the photovoltaic (PV) system, phase change materials (PCMs), thermoelectric generators (TEGs), and cooling water are combined to form a photovoltaic thermal application (PV-PCM/TEG-T) system. The system is also compared with the PV and photovoltaic phase change thermal (PV-PCM-T) systems for environmental and economic analyses. The environmental analyses shows that the environmental impacts of the three systems are mainly concentrated in the production phase, with the aluminum frames and PV panels being the primary sources of the environmental effects, while the addition of paraffin wax and TEG have relatively minor environmental impacts. Economic analyses shows that the system generates electricity for 0.076 $/kW h, with the purchase of TEGs being the main capital expenditure. At the same time, the energy payback time of this system is 17.5 % shorter than that of the PV system and 6.9 % shorter than that of the PV-PCM-T system. The life cycle conversion efficiency is 55 % higher than that of the PV system and 23.9 % higher than that of the PV-PCM-T system, which provides better energy saving. In addition, with the continuous development of TEG manufacturing technology, the PV-PCM-TEG-T system will have better economic benefits and application potential.

A shape-stable phase change material for high-temperature thermal energy storage based on coal fly ash and Na2SO4-K2SO4

Using coal fly ash (CFA) as the skeleton material and binary sulfates of Na2SO4-K2SO4 as the phase change material (PCM), high-temperature coal fly ash based phase change thermal storage materials (CPCM) were successfully synthesized. The influences of CFA fractions and types on the morphology, physicochemical properties, and thermal characteristics of the composites were intensively investigated. Results show that the heat storage density and thermal conductivity of CPCMs increase with the PCM content. Particularly, the CPCM60-A composite, comprising 60 wt% Na2SO4-K2SO4 eutectic and 40 wt% CFA-A, exhibits excellent chemical compatibility and stable shape retention after sintering. Furthermore, CPCM60-A demonstrates the highest phase change latent heat of 60.43 J/g and thermal conductivity of 0.61 W/(m·K). The influence of CFA types reveals that CFA-A with a higher ratio of SiO2 and Al2O3, lower carbon content, and a rich porous structure is more suitable to fabricate molten salt heat storage materials. This work demonstrates that CFA, a byproduct of coal-fired industry, is a promising skeleton material for the fabrication of high-temperature CPCM composites, offering a novel approach for enhancing the efficiency and cost-competitiveness of solar power and waste heat recovery systems.

Experimental investigation of thermal performance in a shell-and-tube phase change thermal energy storage unit with an inner square tube

Experimental investigations of phase change processes in a shell-and-tube latent heat thermal energy storage unit with an inner square tube were carried out. Paraffin OP44E was selected as a phase change material, and the water heated or cooled by constant temperature water tanks flowed into the inner square tube as the heat transfer fluid. Visualization experiments allow for the observation and analysis of the solid-liquid interface during the phase change process. Due to natural convection, the melting interface progresses from top to bottom, while the solidification interface advances from the center outward, as heat transfer is primarily governed by conduction. The experimental results demonstrated that the initial temperature of the PCM has a negligible impact on the thermal performance of the energy storage unit, particularly during the solidification process. The dimensionless analysis reveals the relationships of Nusselt numbers, Stefan numbers, and Reynolds numbers. Furthermore, four stages of conduction, mixed conduction-convection, convective enhancement, and convective attenuation were divided according to the effects of natural convection. Finally, empirical formulas for effectiveness were established to provide guidance for the heat exchanger design.

Numerical simulation of heat transfer performance and convective vortex evolution in a phase change thermal storage device with dispersed heat sources

Numerical simulation of heat transfer performance and convective vortex evolution in a phase change thermal storage device with dispersed heat sources

Design, analysis and optimisation of a novel adiabatic-isothermal CAES system with coupled stepped phase change energy storage unit

Compressed air energy storage (CAES) technology is one of the important technologies to address the instability of renewable energy sources. To further make full use of the system heat of compression and reduce the problem of energy grade dissipation inside the accumulator, this paper proposes a novel CAES system coupled with a graded phase change thermal energy storage unit (SP-TES) and near isothermal compression of a liquid piston. A combination of adiabatic compression and near-isothermal compression is used to reduce the generation of compression heat, while the graded storage of compression heat through SP-TES reduces the reduction of energy grade. The design of the proposed SP-TES is carried out through the binary eutectic theory, and a one-dimensional transient entransy dissipation model, a thermodynamic model and an economic model are developed to analyze the 4E performance (energy, exergy, entransy, and exergoeconomic) of the proposed SP-TES. Further, the effect patterns of key node parameters on the proposed system are investigated by developing system related models and the system is optimized with multiple objectives from the point of view of economic and thermodynamic performances. The results show that the 4E performance of SP-TES is in between that of high and low temperature single-stage accumulators, and that SP-TES combines the advantages of higher economic performance of single-stage low-temperature accumulators and higher thermal performance of single-stage high-temperature accumulators. The SP-TES with a temperature range of 350 K-451 K is gradually stabilized with the number of charging and discharging, and the efficiency of the system in the stabilization stage is 73.24 %. The SP-TES with a temperature range of 407 K-440 K has the best economic performance with exergoeconomic parameter of 360.05 kJ/USD. The thermal storage performance and power output of the SP-TES decreases with the increase in the number of stages. The multi-objective optimization results show that the new CAES system efficiency is 63.03 % and the design is optimal when the unit energy cost is 0.2217 $/kWh.

Phase change energy storage using boron nitride/carbonized loofah sponge

Phase change thermal energy storage is a novel option for industrial waste heat recovery with the characteristics of high safety performance and low-cost. This work explores the potential novel composite phase change materials by encapsulating polyethylene glycol with boron nitride, carbonized loofah sponge fragments and boron nitride-carbonized loofah sponge fragments mixture using melt impregnation method. The results reveal that there is no chemical reaction between polyethylene glycol and the additives of boron nitride and carbonized loofah sponge fragments. The maximum thermal conductivity of the polyethylene glycol-based composites is 1.09 times of the pure polyethylene glycol. The thermal energy storage efficiency of polyethylene glycol/carbonized loofah sponge fragments composites with 2.5 wt% additives can be up to 80.13 %. The maximum temperature variation rates in the heating and cooling processes are attributed to polyethylene glycol/carbonized loofah sponge fragments, which are 0.096 °C/s and 0.057 °C /s correspondingly. Based on the numerical simulation considering utilization of waste heat from flue gases, the total melting time of composites with boron nitride, carbonized loofah sponge fragments, and boron nitride-carbonized loofah sponge fragments are 82.61 %, 85.25 % and 81.86 % of pure polyethylene glycol. These results imply the multiple usage of additives could not have superimposed effect on decrease of latent heat, and carbonized loofah sponge fragments is a cheap alternative to boron nitride.

Novel modular PCM wall board for building heating energy efficiency: Material preparation, manufacture and dynamic thermal testing

With the comprehensive implementation of China’s “dual carbon” goals, the building heating sector, characterized by high energy consumption and emissions, urgently requires low-carbon transformation. However, energy-saving measures for plateau regions are scarce and face challenges due to harsh climates. This study proposes an innovative heating method utilizing composite phase change materials. A new modular phase change thermal storage electric heating terminal integrated with a photovoltaic thermal system has been designed to address issues of high building energy consumption and problems related to heating system freezing and leakage in the Tibetan Plateau (Qinghai-Xizang Plateau). Laboratory tests were conducted on six groups of samples with different structures and placements to examine their heat storage and release characteristics. Results indicate: The system’s temperature stabilization time totals 14.6 h; Horizontally placing the terminal reduces melting time by up to 2.7 h, enhancing heat storage performance; Structure three shortens solidification time by up to 2.2 h compared to structure one, improving heat release performance; Vertically placed terminals have better heat release performance than horizontally placed ones, resulting in more effective indoor heating. This study proposes a modular design for phase change heat storage electric heating walls, simplifying installation and maintenance while maintaining aesthetic appeal. Detailed temperature measurements of different wall surfaces revealed excellent cyclic heat storage and release performance. The developed phase change heat storage electric heating terminal is expected to significantly reduce heating energy consumption in the Tibetan Plateau (Qinghai-Xizang Plateau), enhancing building energy efficiency and providing valuable insights for further applications of phase change materials in building design.

Experimental and numerical analysis of cosine wave heat source on thermal storage performance of a conical spiral shell-tube energy storage system

Solar radiation is the main driving force for the energy source of solar collectors, and its intensity determines the amount of energy that solar collectors can absorb. Therefore, the periodicity of radiation intensity will lead to periodic fluctuations in the outlet water temperature of solar collectors. This study numerically investigates the effects of the heat source period, amplitude, inlet flow rate, and steady state heat source temperature on the thermal storage performance of conical spiral shell-tube energy storage systems when the inlet temperature varies periodically as a cosine function using fluent software. The results show that when heat source periods are between 5 and 300 min, compared to the constant heat source, the total energy storage capacity can be increased by a maximum of 7.32 %. The melting time can be shortened by a maximum of 16.31 %. The average energy storage rate and energy storage efficiency can be increased by a maximum of 4.08 % and 0.17 %, respectively. When amplitudes are increased from 0 to 20 K, the melting time, total energy storage capacity, and energy storage efficiency are reduced by 30.21 %, 1.19 %, and 1.64 %, respectively. The average energy storage rate increases by 41.59 %. Furthermore, compared to the constant heat source, increasing the inlet flow rate and steady state heat source temperature has more significant effects on the thermal storage performance under cosine wave heat sources. The results can provide some reference for the optimization of phase change thermal storage systems under unsteady state conditions.

Uncovering Temperature-Insensitive Feature of Phase Change Thermal Storage Electrolyte for Safe Lithium Battery.

Lithium-ion batteries (LIBs) have emerged as highly promising energy storage devices due to their high energy density and long cycle life. However, their safety concern, particularly under thermal shock, hinders their widespread applications. Herein, a temperature-insensitive electrolyte (TI-electrolyte) with exceptional resistance to thermal stimuli is presented to address the safety issues arising from the lack of thermal abuse tolerance in LIBs. The TI-electrolyte is composed of two phase-change polymers with differentiation melting points (60 and 35°C for polycaprolactone and polyethylene glycol respectively), delivering a wide temperature-resistant range. It is demonstrated that the TI-electrolyte possesses a heat capacity of 27.3Jg-1. The crystalline region in the TI-electrolyte shrinks when confronted with above-ambient temperature, absorbing heat to unlock molecular chains fixed in the crystal lattice, becoming amorphous. Notably, the Li||LFP pouch cell delays 3 valuable minutes to achieve the same temperature as conventional liquid electrolytes (LE) when subjected to thermal shocks, paralleling with the simulation results. Moreover, symmetrical Li||Li cell cycles stably for over 600h at 0.1mAcm-2, and Li||LFP full cell demonstrates excellent electrochemical performance, with a capacity of 142.7mAhg-1 at 0.5C, thus representing a critical approach to enhancing the safety of LIBs.

Development and thermal property analysis of biobased binary composite heat storage materials

Natural aliphatic dibasic acids are a type of bio-based material that shows promising potential as green phase change thermal storage materials due to their favorable thermophysical properties. However, these materials have been found to have issues with subcooling, low thermal conductivity, and poor temperature matching. In this study, three aliphatic dibasic acids, namely adipic acid (AA), sebacic acid (SA), and azelaic acid (ZA), were selected for further investigation. Three biobased eutectic systems, AA-SA (melting point: 118.3 °C), ZA-SA (melting point: 96.2 °C), and AA-ZA (melting point: 98.4 °C), were then prepared based on the calculation of Schrader's equation and experimental screening. The eutectic systems were thoroughly characterized, revealing thermal conductivities ranging from 0.4 to 0.5 W·m−1·K−1, with all systems exhibiting a subcooling of around 20 °C. Based on the principle of optimal overall performance, the AA-SA system was selected for modification. By incorporating Expanded graphite (EG) as a highly thermally conductive additive and nucleating agent, the AA-SA/EG composite phase change material (CPCM) was successfully prepared. This modification effectively reduced the supercooling degree of the bio-based phase change materials (PCM) and significantly improved its thermal conductivity by a factor of four. The resulting AA-SA/EG CPCM demonstrated excellent temperature suitability and has the potential to contribute to the application of bio-based phase change materials in waste heat recovery and solar energy systems. This study provides valuable insights into the development and optimization of bio-based phase change materials, contributing to the sustainable utilization of renewable resources for thermal energy storage applications.

Efficient utilization of cold energy enabled by phase change cold storage brine gels with superior thermophysical properties towards biochemical reagent cold chain

Phase change cold storage, as an emerging cold chain method of maintaining a low-temperature environment and effectively ensuring the quality of biochemical reagents, is extensively utilized because of its benefits of high energy density, low cost, energy conservation and environmentally friendly mode. However, the low thermal conductivity of working medium affects its cold charging/discharging rate and operating efficiency. Meanwhile, the high leakage characteristic in the phase change process leads to a decrease of cold storage capacity and contamination of items. This work proposes the efficient utilization of cold energy enabled by leakage-free phase change cold storage brine gels with extraordinary high thermal conductivity towards biochemical reagent cold chain. Phase change thermal storage gel is prepared by confining brine in the sodium polyacrylate‑calcium alginate network and porous adsorption of expanded graphite. The prepared materials present leak free characteristics and almost 100% mass retention rate. Expanded graphite addition enables the thermal conductivity increase from 0.542 W m−1 K−1 to an extremely high value of 2.766 W m−1 K−1 (an increase of 510%). The enthalpy value of the cold storage brine gel is as high as 144 Jg−1, stably releasing cold at around −24 °C. By regulating the distribution of cold storage working medium, the minimum temperature difference inside the apparatus can be reduced from 6.7 °C to about 1 °C. Finally, performance-enhancing phase change cold storage materials and apparatus in the cold chain of biological reagents is fruitful, effectively providing a long-lasting and uniform low-temperature environment.