Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

Quantum Dots and Their Applications: What Lies Ahead?

Personal thermal management by thermally conductive composites: A review

Heat stress affects personal health and curtails work productivity, resulting in adversely influencing the entire economy. With global warming and expected climate change, the world faces more frequent and intense heatwaves that may cause severe sustainability-related challenges. Therefore, there is an urgent need to develop and promote efficient technologies to regulate personal thermal comfort under both indoor and outdoor conditions. Thermoregulation of the human body by using advanced personal thermal wears is one such promising technology, given the fact that it is a cheap and sustainable solution to overcome health hazards, environmental concerns and consequently a significant reduction in energy consumption on building cooling and heating. This paper reviews the research work related to personal thermal management and discusses its implications on personal comfort. Based on heat transfer mechanism and structural characteristics, we categorized the textiles based on passive heat dissipation (radiative sky cooling textiles, and thermal conductive textiles), active cooling/warming (air-cooled, water-cooled, PCMs-cooled and composite textiles), and responsive textiles (temperature/heat-responsive textiles and moisture-responsive textiles). Besides, this review puts forth an in-depth study on the advancements in personal thermal management along with the emerging materials, such as biomimetic materials, metamaterials, nanomaterials and nanocomposite, and it provides valuable insights regarding the barriers and scalability of such textiles.

Fundamentals, materials and strategies for personal thermal management by next-generation textiles

Integrating phase change materials (PCMs) with polymers is expected to develop novel polymeric composites with heat storage capacity, thus showing potential applications in thermal management. Microencapsulation of solid-liquid PCMs by organic or inorganic shells can effectively prevent liquid leakage from the PCMs, thereby improving their application performance. Herein, phase change microcapsules with SiO 2 shell were combined with polydimethylsiloxane (PDMS) to construct a novel kind of polymeric composite. It is shown that an interfacial interaction between the paraffin@SiO 2 microcapsules and the PDMS occurs, which endows the two components with good compatibility. The paraffin@SiO 2 microcapsules/PDMS composites exhibit slightly higher phase change temperatures than those of the microcapsules. The mass fraction of the microcapsules in the PDMS-based composites can reach 38.89 wt%, at which a latent heat value of 60.61 J/g is achieved, together with an enhancement by 80.71% in thermal conductivity as compared to that of pure PDMS. When the paraffin@SiO 2 microcapsules/PDMS composite was employed for chip thermal management, the chip temperature reduced by 15.87%, compared with that using the one without any phase change microcapsules. It is revealed that the paraffin@SiO 2 microcapsules/PDMS composites possess good thermal reliability. These merits make the paraffin@SiO 2 microcapsules/PDMS composites show great promise in practical applications. 

Compatible paraffin@SiO2 microcapsules/polydimethylsiloxane composites with heat storage capacity and enhanced thermal conductivity for thermal management

Thermal interface materials with sufficiently vertically aligned and interconnected nickel-coated carbon fibers under high filling loads made via preset-magnetic-field method

In quantum-dots-converted white-light-emitting diodes (QDs-WLEDs), red-emitting quantum dots are usually mixed with yellow-emitting phosphors in luminescent polymer layer to achieve a high color re...

White-Light-Emitting Diodes from Directional Heat-Conducting Hexagonal Boron Nitride Quantum Dots

Liquid-cooled garment (LCG) is a promising personal thermal management (PTM) technique that satisfies the individual thermal comfort requirement by creating a microclimate around the human body. Thermal sensation, which is defined as “the wearer’s sense of temperature between hot and cold,” is a helpful target for designing an LCG with good thermal comfort. There are just a few methods to predict the thermal sensation of the LCGs. In addition, the previous prediction methods related to the conventional heating, ventilation, and air conditioning (HVAC) systems cannot be directly applied to the LCG, due to the lack of consideration of some dominating characteristics of the LCG and the human body. To solve this problem, a neural network model was proposed to predict the thermal sensation of wearers of LCGs, taking physiological parameters [heart rate (HR), skin temperatures, and tympanic temperature] and physical parameters [ambient temperature (AT) and relative humidity (RH)] including water inlet temperature of LCGs into consideration. Experiments were carried out to obtain the model training data under various conditions. After optimization, the neural network model performs excellently, which shows the potential to predict the thermal sensation for LCGs. The correlation analysis indicates that water inlet temperature is the most correlated parameter to thermal sensation in LCGs.

Thermal Sensation Modeling and Experiments for Liquid-Cooled Garments

Piezoelectric pump, driven by piezoelectric actuator, is one of the most promising micropumps in compact system. However, the application of piezoelectric pump is limited by the check valve, which is not efficient enough and needs careful fixation. This work presents a novel design with unfixed check valve, which greatly simplifies the assembly of valve-based piezoelectric pump and improves the output performance. The valve is unfixed with a small gap to obtain variable stiffness at different working stages, making it open more quickly. The piezoelectric pumps with three different valve gaps were designed, fabricated, and tested. The pump with the unfixed valve shows a 25.6% flow rate improvement compared with the fixed check valve without reducing the output pressure. To reveal the mechanism of the flow rate improvement, we investigated the flow resistance and the volumetric efficiency of the piezoelectric pump. The results show that the unfixed valve increases the volumetric efficiency of the piezoelectric pump, which improves the flow rate. The prototype pump achieved the maximum output performance of 162 ml min−1 and 33 kPa. The power consumption was less than 100 mW, reaching a pump efficiency of 21.7%.

Xinfeng Zhang

Papers

Thermal interface materials with sufficiently vertically aligned and interconnected nickel-coated carbon fibers under high filling loads made via preset-magnetic-field method

White-Light-Emitting Diodes from Directional Heat-Conducting Hexagonal Boron Nitride Quantum Dots

Thermal Sensation Modeling and Experiments for Liquid-Cooled Garments

Development of a piezoelectric pump with unfixed valve

Radially oriented functional thermal materials prepared by flow field-driven self-assembly strategy