Recent advances in low-temperature phase change materials for cold chain logistics

Development, characterization and modification of mannitol-water based nanocomposite phase change materials for cold storage

Low-temperature macro-encapsulated phase change material based thermal energy storage system without air void space design

Development of low-temperature eutectic phase change material with expanded graphite for vaccine cold chain logistics

With the intensification of global warming and the explosive growth of cold chain logistics demand, the energy consumption and carbon emissions of refrigeration systems are becoming increasingly prominent. Phase change materials (PCMs) show broad application prospects in cold chain transportation, building energy conservation, electronic cooling and smart textiles due to their high latent heat energy storage density and temperature control capabilities. however, conventional phase change materials suffer from problems such as supercooling, phase separation, leakage and poor thermal conductivity, which limit their practical application. Microcapsule encapsulation technology effectively solves the above problems by constructing a core-shell structure, significantly improving the stability and thermal response efficiency of the material. This paper systematically reviews the classification, properties and current status of low-temperature phase change materials in different fields, focusing on the preparation methods, wall material selection, modification strategies and research progress of phase change microcapsules in improving thermal conductivity and suppressing supercooling. Studies have shown that the comprehensive performance of phase-change microcapsules can be significantly improved through the modification of shell and core materials, providing theoretical basis and technical support for their large-scale application in high-efficiency energy storage and temperature control systems. Future research should further focus on the development of multifunctional composite microcapsules, the optimization of large-scale manufacturing processes, and the feasibility and economic analysis of their integration into renewable energy storage and intelligent thermal management systems.

Preparation and thermal properties of low-temperature composite phase-change materials based on a binary eutectic mixture with expanded graphite: Effect of particle size and mass fraction

The effect of low temperature phase change material of hydrated salt on the performance of magnesium phosphate cement

This article analyses the use of low-temperature PCMs in devices supplementing a room ventilation system to prevent the overcooling effect. In this study, the phase change is numerically simulated in an axisymmetric system consisting of two tubes. One is filled with RT11HC with an initial temperature of 0 °C, while air with an inlet temperature of 20 °C flows through the other, heating the PCM and causing it to melt. Calculations are performed using commercial software with the apparent heat method for a system of given dimensions. Spatial distributions of the system temperature and liquid volume fraction at different time moments (from 0 to 120 min) are determined. It is found that the results depended mainly on the method of determining the latent heat. For the beginning of the charging process (t < 40 min), the values of the liquid phase fraction determined by the H and S methods are similar, while the one determined by the G method is definitely higher (even three times at t = 10 min). In turn, the outlet air temperature determined by the S method is lower than that determined by the other methods. The size and shape of the mesh have no significant effect on the results.

Robots have been around us for quite some time now. Robots are machines capable of performing tasks on their own with high accuracy and precision and minimal supervision to reduce human effort. Our daily lives are touched by different forms of robots around us, be it a direct interaction in form of robotic helpers at the airport or indirectly in the case of industrial arm robots assembling the electronics and machines. Traditionally, there are several component systems to robotics and one of the prominent one is actuation, which is made from hard and rigid components in these conventional robots. However, this is responsible for their intermittent motion. A new field of research, soft robotics, makes of soft materials for their fabrication and draws inspiration from natural organisms and how they produce fluidic and complex motions. There are different ways by which these soft materials can be actuated and include techniques like applying pneumatic and hydraulic pressure, applying heat, making use of a chemical process like combustion, applying varying magnetic fields and applying electric fields. Among these, the class of actuators employing soft materials deformed by applying the electric field, known as Dielectric elastomer actuators, are preferred owing to their advantages of simple fabrication, large actuation strain and control by electrical stimulus. The architecture of these actuators resembles a variable capacitor with electrodes on either sides of the elastomer, and their performance depends on material properties like dielectric constant and mechanical stiffness. Generally, researchers have tried to modify either of these properties with addition of solid conductive or ceramic fillers, or chemical modification of the elastomer, and this has led to undesirable changes on the other material properties. Drawing inspiration from biological materials like skin, which is a soft material system filled with fluids, a novel composite is synthesized utilizing a solid polymer matrix and a high dielectric constant liquid filler, an ionic liquid. An increase in dielectric constant is observed accompanied with significant reduction in mechanical stiffness. The novel composites show significant improvement upon the actuation performance of the commonly used elastomeric system at considerably low electric fields. Owing to the judicious choice of material systems, the composites also show high stability and transparency. With emergence of new generation technologies such as display touchscreens, touchpads, virtual reality and augmented reality, human machine interaction and haptics has become ever more important. Soft actuators and dielectric elastomer actuators (in particular), owing to their inherent softness, have convincing advantage over the conventional rigid actuators. Additionally, state-of-the-art technologies for haptics primarily seek to simulate the perception of texture change with sensory manipulation. Furthermore, dielectric elastomer actuators in their current form suffer from visible obstructiveness and non-integrable architecture. A new device architecture for dielectric elastomer actuators, capable of producing on-demand surface texture change and local topographic features, is demonstrated. Owing to its unique architecture, a highly transparent, flexible and integrable configuration of the device is showed. Out-of-plane deformations and force feedback from the devices are shown to be well above the perceptual threshold of sensors, known as mechanoreceptors, present in our fingertips. Another attribute of the biological appendages in natural organisms is the ability to reversibly modulate its mechanical properties upon demand, which still eludes the field of soft robotics. One of the best examples of this is found in human body, where muscles modulate their stiffness in accordance to the load distribution and movement. Most of the current approaches mange to only demonstrate reversible stiffness and involves combination of a passive reversible stiffness component with the existing actuator. Hence, a novel low-temperature phase change material is identified for enabling reversible rigidity in the soft actuators owing to its low melting point, significant gap between melting and solidification, superior thermal stability, high mechanical strength and high dielectric constant. Thermal control is chosen the modulation of mechanical properties, owing to its lightweight design and scalability. The fabricated reversible rigidity composites show impressive variations in stretchability, bendability and hardness. Owing to its ability to melt and re-solidify, the composites also demonstrate a healing behaviour with the ability to regain complete structural integrity and mechanical strength. These novel ultra-soft, high-k liquid filler-based polymer composites, reversible rigidity composites and transparent and integrable device architectures for field-driven soft actuators could pave the way for next generation applications such as shape morphing, adaptive surfaces and transparent haptic devices.

Low-temperature phase-change materials (PCMS) were mixed with water to enhance the performance of heat transfer fluid. Several PCMs were tested in a laboratory-scale test loop to check their suitability to district cooling applications. The phase-change temperatures and latent heats of fusion of tetradecane, pentadecane, and hexadecane paraffin waxes were measured using a differential scanning calorimeter. The heat of fusion of these materials is approximately 60% of that of ice. They exhibit no supercooling and are stable under repeated thermal cycling. For 10% and 25% PCM-water slurries, the heat transfer enhancement was found to be approximately 18 and 30 percent over the value of water, respectively. It was also found that, in the turbulent region, there is only a minor pumping penalty from the addition of up to 25% PCM to the water. It was demonstrated that pentadecane does not clog in a glass-tube chiller, and continuous pumping below its freezing, point (9.9[degrees]C):was successfully carried out in a bench-scale flow loop. Adding PCM to water increases the thermal capacity of the heat transfer fluid and therefore decreases the volume that needs to be pumped in a district cooling system. It also increases the heat transfer rate, resulting in smaller heat exchangers. Research is continuing on these fluids in order to determine their behavior in large-size loops and to arrive at optimum formulations.

Stabilizing a low temperature phase change material based on Glaubers salt

Asphalt pavement cracks easily in low-temperature environments. In order to address the problem, phase-change material (PCM) microcapsules working at 0–10°C are used to replace some of the aggregates in asphalt. In this study, PCM microcapsules with a high-temperature epoxy resin adhesive as reinforcement phase were prepared by using n-tetradecane/tetradecanol as the core material and melamine-urea-formaldehyde as the wall material. The reinforced PCM microcapsules were blended into the asphalt modified by styrene-butadiene-styrene block copolymer (SBS) modified asphalt, the PCM microcapsules were used to replace part of the same amount of the coarse aggregate. The results depict that the reinforced PCM microcapsules can satisfy the requirements of both immersion Marshall test and freeze-thaw splitting test. Above all, asphalt mixtures containing reinforced PCM microcapsules have been proved acceptable via dynamic stability tests. The bending beam rheometer test results imply that asphalt mixture containing PCM microcapsules revealed good crack resistance at low temperatures. Compared with the asphalt mixture sample in the reference experiment, the temperature difference of that containing the reinforced PCM microcapsules could reach 2.1°C, indicating a promising application prospect.

Cold chain transportation refers to a logistics method that transports fresh, perishable, and perishable items from the place of production, processing or warehouse to the place of consumption under certain temperature conditions. As consumers have higher and higher requirements for food safety and quality, the cold chain logistics industry has also developed rapidly. However, the high cost of cold chain logistics, the difficulty of technology, the difficulty of ensuring service quality and other problems have also arisen, and how to optimize cold chain transportation has become a hot issue in the cold chain logistics industry. Cold chain transportation optimization refers to the premise of ensuring the quality and safety of goods, through reasonable transportation paths, transportation methods, temperature control and other measures, to minimize the cost of cold chain transportation, improve efficiency and service quality. In order to achieve the optimization of cold chain transportation, it is necessary to establish a reliable cold chain logistics distribution center to ensure the safety and quality of goods during transportation. In order to solve the problem of location selection of cold chain logistics distribution center, this paper first defines the service reliability and calculation method of cold chain distribution center. Then, the location model of the cold chain logistics distribution center and the trust domain optimization algorithm model were established. The model aims to minimize the total cost, while considering multiple factors such as transportation distance, temperature control, facility construction, etc., to ensure the reliability and operational efficiency of the cold chain logistics distribution center. Finally, this paper introduces an example for calculation to prove the feasibility and universality of the model in the location problem of cold chain logistics distribution center. Through the calculation of examples, it can be seen that the model can effectively reduce the cost of cold chain transportation and improve the service quality and efficiency of cold chain logistics distribution center. In summary, this paper proposes a reliable location model and trust domain optimization algorithm model for cold chain logistics distribution centers to solve the challenges faced by the cold chain logistics industry. This model can provide guidance for cold chain logistics companies to gain a greater advantage in a highly competitive market.

Modeling of a heat exchanger utilizing a phase-change material for short-term storage

Objectives Our objectives are to study the development and historical evolution of the bio/pharma cold-chain logistics industry in China. Bio/pharma cold-chain logistics has attracted a large number of scholars whose research has resulted in patents. Cold-chain modes like cold-chain transportation, cold-chain circulation, low temperature and multi-modal transportation have played an important role in bio/pharma cold-chain logistics. The implementation of cold-chain logistics also guarantees that the bio/pharma will always be kept at a low temperature state during the circulation process. The highlighted issues of drug safety make this more important. Statistically, the rates of cold-chain circulation and cold-chain transportation in China are 20% and 30%, compared to more than 90% in developed countries. Therefore, it is necessary for scholars to carry out scientific research on cold-chain logistics. Methods A scientific literature database including a patent information services platform was used. Data visualization methods such as a patent management map, quantitative methods and bibliometrics were used to study patents. Results The results revealed that the bio/pharma literature and cold-chain logistics technologies have increased substantially. Institutes and universities are the main forces behind basic research, and bio/pharma enterprises have begun to focus on intellectual property protection and technological innovation. Conclusions Institutes and enterprises should be encouraged to carry out cooperative research on bio/pharma cold-chain logistics, to promote cold-chain resource integration and transfer to the Midwest, and to strengthen bio/pharma enterprises to speed up investment in the secondary market in China. Acknowledgments This research was financially supported by the Foundation of Philosophy and Social Science Program of He’nan Province (Grant No. 2015BZH012) and the Foundation of He’nan Educational Committee (Grant Nos. 15B630005 and 2015-ZD-048). The authors would also like to thank anonymous reviewers for their valuable comments.

This study introduces concepts of the agricultural product cold chain logistics and domestic and international researches. Also, the study discusses issues of Chinese agricultural cold chain logistics in the development process as the following aspects: the dividing of cold chain logistics market, refrigeration hardware facilities, third-party cold chain logistics development, the level of cold chain technologies, cold chain logistics professionals and the legal system and the standard system. Next, this study focuses on the countermeasures to solve problems of the agricultural cold chain logistics development by some ways as followings: increasing investments in technology, accelerating the improvement of the cold chain logistics facilities, strengthening the cultivation of third-party cold chain logistics enterprise, encouraging the training of personnel, promoting the cold chain logistics informatization and improving relevant laws, regulations and standards. Combining with the cold chain logistics of Mengniu Dairy, this study analyzes and proposes countermeasures. Finally, this study summarizes the developments in Chinese agricultural chain logistics, which needs to be strengthened in many aspects for suiting Chinese situation.