最新刊期
- 摘要：This study provides a systematic review of the emerging twistocaloric cooling technology， which shows significant potential for the applications in high-efficiency solid-state refrigeration by driving reversible microstructural changes via twisting and untwisting. Firstly， the mechanism and mathematical models for refrigeration by the twistocaloric effect are elucidated， revealing the principles for realizing a high entropy change and thermodynamic efficiency. Subsequently， the influences of key factors， including the twist degree and rate， ambient temperature， and geometric parameters of the material， are analyzed， and a comprehensive evaluation system focused on the hysteresis effects， coefficient of performance （COP）， and fatigue life is established. Based on the analyses， the research progress of materials like natural rubber， polymers， and NiTi shape memory alloys are reviewed in detail， verifying that twistocaloric cooling yields significant temperature changes while offering the integrated advantages， e.g.， a high COP and low hysteresis and an excellent cyclic stability. Finally， the application potentials of twistocaloric cooling in fields such as the microelectronic cooling and green refrigeration are discussed， indicating the critical value of the "twist-instead-of-stretch" technical pathway in advancing the development of solid-state refrigeration.关键词：twistocaloric cooling;elastocaloric effect;solid-state cooling;shape memory alloy;polymer9|31|0更新时间：2026-07-15
- 摘要：In response to the urgent demand for large-scale transoceanic transportation of liquid hydrogen， this study focuses on an 8 000 m³ Molten Salts Storage （MOSS）-type marine liquid hydrogen spherical tank for a thermal-structural multiphysics coupling analysis and structural integrity assessment in liquid hydrogen temperature zone. A three-dimensional finite element model is developed， incorporating a composite insulation layer of hollow glass microspheres （HGM） and a resilient blanket integrated with composite support components. In accordance with International Maritime Organization （IMO） regulations， three typical navigation conditions—namely， the Equator， International Gas Carrier code， and United States Coast Guard standards—are simulated. Thermodynamic calculations demonstrate excellent insulation performance， yielding boil-off rates between 0.123% and 0.158% across all operating conditions， thereby satisfying the design target （0.2%）. Mechanical analysis reveals that the thermal strain induced by the extreme cryogenic temperature （-253 ℃） dominates coupled deformation and leads to significant stress concentration at support joints. Using stress linearization in accordance with ASME VIII-2 design-by-analysis standard， the local peak stress is effectively separated. The results show that the maximum combined primary and secondary stress is 493.6 MPa， which is below the allowable stress limit of 600 MPa. This study elucidates the multiphysics coupled mechanical response characterisitcs of large-scale MOSS-type liquid-hydrogen spherical tanks under extreme operating conditions， providing practical engineering references and technical insights for the structural design， insulation optimization， and safety assessment of seaborne liquid-hydrogen storage and transportation equipment.关键词：liquid hydrogen spherical tank;thermal-structural coupling;hollow glass microspheres;boil-off rate （BOR）;stress linearization7|20|0更新时间：2026-07-15
- 摘要：Objective Under the framework of China’s dual-carbon targets， district heating systems are shifting from coal-fired sources to multi-sources together with multi-sink modes dominated by waste heat. A unified network should integrate heat sources and heat sinks whose temperature grades vary over an extremely wide range. However， existing series-cascade approaches require heat exchange units to be arranged strictly in the order of grades， limiting their applicability in complex networks. This study proposes a generalized framework， with termed temperature grade sharing， which redistributes the temperature grade among adjacent heat exchange processes through additional bypass pipes， thereby decoupling grade matching from the physical arrangement.MethodsThe average temperature difference of source–sink is defined to quantify the grade mismatch， which classifies the system into four scenarios： heating-supply deficiency or surplus， and heat-recovery deficiency or surplus. Four configurations were constructed correspondingly： heating-supply upper--three-pipe and lower-three-pipe systems and heat-recovery upper--three-pipe and lower-three-pipe systems. Entransy dissipation analysis was adopted to demonstrate that grade sharing converted single large-temperature-difference mixing into small-temperature-difference mixing across both interfaces， ensuring a strict reduction in mixing losses. An analytical relationship was then developed to correlate the achievable reduction in the network return temperature with the original return-side mixing temperature difference and relative heat load of the grade-deficient process.Results and Discussions Based on the analytical relationship between the reduction in the mixing-entransy dissipation and heat load of total branch， an analytical design map was established for the impact of temperature grade sharing on the overall network return temperature （Fig. 11）. Operating under a large-temperature difference， a low-return temperature route with the fixed supply temperature and heat load， allows a substantial reduction in the return temperature. The low return temperature enhances the transport temperature difference and reduces the required flow rate of circulation， thereby establishing the conditions for expanding network transport capacity and multi-source waste-heat integration without enlarging pipe diameters or equipment scales. For a representative boundary， i.e.， a relative heat load of 20% and an original mixing temperature difference at return-side of 20 K， the network return temperature can be lowered by 1.57 K， which aligns with the analytical map. The four configurations collectively cover all four typical mismatch scenarios； their design parameters are identical， and within a branch， the borrowed and returned grades offset one another， leaving the total driving force unchanged. At equipment level， an absorption heat exchanger requires only an additional bypass pipe and a circulating pump； while no extra heat-exchange components are required.ConclusionThe proposed temperature-grade sharing framework decouples the cascade utilization from the physical arrangement. It provides a methodological foundation and a viable engineering pathway for the system-wide allocation of temperature grades in waste-heat-driven district heating systems， supporting the flexible integration and dynamic operation of multi-source together with multi-sink networks during dual-carbon transition.关键词：district heating;temperature grade sharing;waste heat utilization;large temperature difference heating;multi-source multi-sink;absorption heat exchanger11|34|0更新时间：2026-07-10
- 摘要：Cleanroom air conditioning in microelectronics requires high energy input， high precision， and continuous operation， accounting for 40%–60% of the total plant energy consumption. Most reviews concentrate on a single technology and lack systematic classification and engineering adaptation analysis. Thus， they fail to support low-carbon manufacturing for advanced processes and dual carbon goals. Focusing on systematic energy savings， this study used bibliometric analysis and inductive review to summarize key technical routes， application fields， and research developments across four aspects： air systems， cold and heat sources， intelligent control， and energy recovery. Technical limitations are also analyzed， and future development trends are predicted. The results indicate that improvement of air systems， rational allocation of cold and heat sources， intelligent control techniques， and energy recovery technologies can achieve an energy-saving rate of 10%–39%. Multi-technology integration and cooperation， digital twins， and low Global Warming Potential （GWP） refrigerants have emerged as dominant research themes. The industry still faces significant challenges， including low technology implementation rates， unresolved coupling mechanisms， a lack of comprehensive life-cycle evaluations， and divergent industry standards. This study builds a complete energy-saving technology framework and clarifies the potential energy-saving and optimization directions， with the aim of providing a systematic theoretical framework and an engineering foundation for the energy-saving design， operational optimization， and technological upgrading of cleanroom air conditioning systems in microelectronics.关键词：microelectronics industry;cleanroom air-conditioning system;energy-saving optimization;intelligent control12|44|0更新时间：2026-07-10
- 摘要：To investigate the effects of fin pitch， refrigerant charge， superheat control， and insulation thickness on the performance of packaged R290 integrated heat pump water heaters and optimize their performance. An evaporator-side simulation model was developed， and the experimental research on the packaged R290 integrated heat pump water heaters was conducted under nominal operating conditions by systematically evaluating the specific effects of various variables on system performance. The results indicate that heat transfer capacity of the evaporator initially increases and then decreases with increasing fin pitch， with an optimal fin pitch of 1.4 mm. Through the optimized superheat control， system heating capacity was further improved. Both the heating capacity and coefficient of performance （COP） exhibited an initial increase followed by a decrease as the refrigerant charge amount increased； the optimal charge amount was 600 g， yielding a heating capacity of 4052 W and a COP of 4.4. Finding the optimal refrigerant charge is crucial to maximize the performance of packaged R290 heat pump water heaters. System performance can also be enhanced by optimizing control logic and evaporator fin pitch. Increasing insulation layer thickness and enhancing evaporator-side air flow rate also significantly improve system performance.关键词：The packaged heat pump water heater;hot water heating performance;fin pitch;refrigerant charge21|39|0更新时间：2026-07-10
- 摘要：ObjectiveTo investigate the thermophysical properties of Fe3O4@SiO2/HITEC composite molten-salt nanofluids for thermal battery applications in ultra-super-high-temperature CO2 heat pump-coupled energy storage systems.MethodsA molecular dynamics model of an Fe3O4@SiO2/HITEC composite molten-salt system was developed. Using a relaxed structure， thermal conductivity， density， dynamic viscosity， specific heat at constant volume， and self-diffusion coefficient of salt ions were systematically calculated at different temperatures.Results and DiscussionsThe results show that within the temperature range of 423-823 K， the thermal conductivity， density， dynamic viscosity， and specific heat capacity of the composite molten-salt system decrease with increasing temperature， whereas the mean square displacement and diffusion coefficient correspondingly increase. Comparison with empirical correlations reported in the literature for pure HITEC molten salt indicates that the temperature-dependent trends of the thermophysical properties in the composite system are typically consistent with those of pure molten salt. Thermal conductivity， viscosity， and specific heat capacity of the composite system are higher than those of pure HITEC molten salt， with enhancement ratios of 61.1%-146.4%， 1.3%-82.4%， and 12.7%-31.5%， respectively. Thus， the incorporation of magnetic core-shell nanoparticles can improve the thermal conductivity and heat storage capacity of the system while reducing its flowability.ConclusionsFe3O4@SiO2 core-shell nanoparticles can improve the overall thermophysical performance of HITEC molten salt， particularly in terms of thermal conductivity and specific heat， while preserving its basic temperature-response behavior. This study provides a molecular-scale reference for designing high-performance thermal storage media in thermal batteries.关键词：Carnot battery;magnetic core–shell nanofluid;HITEC molten salts;molecular dynamics simulations;coupled heat transfer with supercritical CO214|43|0更新时间：2026-07-10
- 摘要：Sodium chloride solutions with different salinities were used to investigate the ice-making characteristics of sodium chloride in a mechanical scraping-type ice-making system. The influences of salinity on the dynamic performance of the ice-making system were systematically studied by analyzing the physical characteristics of ice crystals/ice slurry and the temperature variation law during the cooling phase transition. The results show that the microscopic morphology of ice crystals gradually transforms from flaky to granular as a function of salt content， the particle size continuously decreases， the separation difficulty of the ice-water mixture increases， the freezing point of solution decreases as a function of salinity， and there is an obvious supercooling phase-transition phenomenon. When the mass fractions of the sodium chloride solution are 3%， 5%， and 6.5%， the solution temperatures decrease to approximately -2 ℃， -4.3 ℃， and， -5.3 ℃ respectively， then suddenly increase to -1.4 ℃， -3.6 ℃， and -4.7 ℃ because of the release of phase-change latent heat during the solidification of liquid water， and decrease again after reaching the peak. An empirical formula for the freezing point of the NaCl solution was fitted based on the experimental data， which accurately reflected the phase-transition characteristics of the solution at the supercooling state. The results provide an important theoretical basis and practical guidance for the optimal design of evaporators and the formulation of system operation control strategies for mechanical scraping-type ice-making technology.关键词：scraping-type;sodium chloride;ice slurry;phase transformation crystallization;freezing point depressant5|35|0更新时间：2026-07-08
- 摘要：ObjectiveManaging the parasitic heat load caused by fluorescence is essential for improving the net cooling power of cryogenic optical refrigerators， particularly in parallel configurations. The thermal links must conduct efficient cooling while blocking the anti-Stokes fluorescence （920-1100 nm） from reaching the cold finger. This study aims to design and numerically evaluate several thermal-link geometries for an optical cryocooler with parallel configuration， focusing on maximizing the fluorescence escape capability and minimizing the parasitic heat load.MethodsSix thermal‑link geometries （labeled A-F） were proposed based on two physical strategies， namely optical‑path guiding and surface‑scattering control. A three-dimensional model was developed using an optical simulation software. The model included a Yb3+：LLF cooling crystal as a uniform isotropic fluorescence source， an MgF2 thermal link， and an absorbing baffle. The surfaces of the thermal links were assigned varying Lambertian scattering percentages （0-100%） to represent different roughness levels. A photodetector was placed at the cold‑finger end to quantify the escaping fluorescence energy. Performance was evaluated using the fluorescence escape coefficient （
- 摘要：Following the continuous increase in power density of microelectronic devices， heat dissipation has become a critical bottleneck limiting performance. Although rectangular microchannels offer a large heat transfer area， the flow under purely pressure-driven conditions remains predominantly laminar， and the thermal boundary layer limits further enhancement. In this study， a three-dimensional numerical model was employed to investigate the effects of different electrode configurations on flow field and temperature distribution. A positive electrode arrangement with periodically increasing spacing was proposed， providing the essential insights into the mechanism by which the electric field interacts with the fluid. The results reveal that this periodically increasing arrangement effectively induces periodic vortex structures， referred to as "pseudo-roughness，" near channel bottom. These vortices strongly disturb the viscous and thermal boundary layers， significantly increasing the local near-wall velocity gradient， thereby simultaneously enhancing the convective heat transfer， increasing the overall flow velocity， and improving drag reduction. In terms of the boundary layer velocity， relative to a conventional smooth channel， the periodically increasing arrangement （Structure 1） achieved the highest enhancement of 41.6%， followed by the uniform arrangement （Structure 2） at 36.8%， and the periodically decreasing arrangement （Structure 3） at 32%. This trend was also reflected in the overall performance： the periodically increasing and uniform arrangements improved the performance evaluation criterion （PCE） by 90% and 70%， respectively. Notably， under the identical applied voltage and heat dissipation performance condition， the periodically increasing arrangement reduced the pressure drop by 66.7%， demonstrating a markedly superior overall performance compared with the other two configurations.关键词：electrohydrodynamics;flow characteristics;heat transfer characteristics;boundary laye;electrode14|40|0更新时间：2026-07-08
- 摘要：ObjectiveSmall-intestinal organoids are highly valuable for intestinal physiological research and drug screening. However， their cryopreservation is often limited by low recovery rates as well as structural and functional damage. This study aimed to establish an efficient and stable slow-freezing protocol for small intestinal organoids by introducing controlled ice nucleation （seeding） and optimizing the key cooling parameters.MethodsFocusing on slow-freezing， a seeding step was incorporated into the conventional protocol to investigate the effects of seeding temperature， terminal temperature for ice crystal growth， and cooling rate on cryopreservation outcomes. Evaluations included assessing survival rates， H&E staining for morphology， and immunofluorescence for proliferation markers and junction proteins. RT-qPCR was used to measure the expression of stemness and multilineage markers.Results and DiscussionsSeeding significantly enhanced post-thaw recovery， increasing viability from （85.05±3.06）% to （88.84±1.78）%， with H&E staining revealing better organoid architectural preservation. Parameter optimization identified an optimal protocol consisting of ice nucleation at -8 ℃ followed by cooling at 0.5 ℃/min to -60 ℃. This optimized regimen achieved a significantly higher survival rate （89.02%±2.06%） than the conventional passive cooling box method （83.11%±2.45%）. Morphological and immunostaining analyses demonstrated that recovered organoids exhibited compact structures and enhanced proliferation. Additionally， upregulated expression of stemness， epithelial junction integrity， and multilineage genes confirmed the effective preservation of their full-spectrum differentiation potential.ConclusionsSeeding actively induces ordered ice nucleation， thereby reducing the mechanical damage caused by excessive supercooling. The optimized protocol outperforms traditional methods in survival， structural integrity， and biological function， thus providing technical support for organoid biobanking and standardized applications.关键词：organoids;slow-freezing;seeding;cryopreservation protocol;controlled-rate freezing22|49|0更新时间：2026-06-29
- 摘要：To meet the demands of lightweight design and real-time control in short-duration， high-heat-load thermal management systems， this study investigated the transient discharge performance of a fin-and-tube phase-change cold storage unit to address the limitations of conventional numerical simulations in simultaneously providing physical insight and online prediction efficiency. First， a three-dimensional transient model for the external phase change material based on the enthalpy-porosity method and a one-dimensional transient flow model for the internal refrigerant were established. A coupled three-dimensional/one-dimensional bidirectional thermal framework was developed to reveal the transient response of the cold storage unit under the combined effects of phase-change heat transfer and along-tube pressure drop. The results show that， under typical operating conditions， the average heat transfer rate reaches 88.29 kW over an 80 s operating period. As the phase change proceeds， the thickened liquid layer increases thermal resistance and continuously weakens the heat transfer capacity of the unit. At 80 s， the along-tube pressure drop approaches 0.3 MPa， and the pressure-drop-induced decrease in saturation temperature is identified as the primary cause of the non-monotonic inflection in the outlet temperature. To enable rapid performance prediction， a particle swarm optimization Extreme Gradient Boosting surrogate model embedded with a transport delay criterion and thermodynamic consistency constraints was developed. The prediction results show that the coefficients of determination for the outlet pressure， outlet enthalpy， and average phase change material temperature of the independent test set exceed 0.98. Crucially， the transport delay criterion reduces the root mean square error of the refrigerant outlet temperature prediction from 1.214 ℃ to 0.580 ℃， providing technical support for the rapid performance evaluation of phase-change cold storage systems and system-level model predictive control.关键词：phase change cold storage unit;machine learning;Surrogate model;performance prediction15|39|0更新时间：2026-06-29
- 摘要：ObjectiveAir-cooled， parallel-plate channels used in battery packs， electronic chips， and compact heat exchangers are commonly limited by the trade-off between heat transfer and pressure drop. Although dimpled surfaces can intensify near-wall mixing at a relatively low manufacturing cost， their overall thermal-hydraulic performance is highly sensitive to the geometric configuration. To address this issue， this study investigates a novel parallel-plate channel equipped with a dimpled plate featuring reverse-side protrusions. This study aims to clarify the effects of major geometric parameters on the coupled flow and heat transfer characteristics， and to identify an optimal compromise design that enhances heat transfer while suppressing the pressure drop.MethodsA three-dimensional， periodic unit of a plate channel was established and solved using steady-state computational fluid dynamics. Air was treated as an incompressible fluid with constant thermophysical properties. Periodic boundary conditions were adopted for the inlet and outlet of the computational domain. Grid independence was achieved at approximately 5.68 million cells. The numerical method was validated against published pillow plate experimental data. Three geometric parameters were selected as decision variables， namely the depth of the large dimple （R1=2.5-4.0 mm）， the depth of the small dimple （R2=0.5-2.0 mm）， and the dimple inclination angle （α=30°-60°）. A total of 64 design cases were used to construct the sample database. Based on these CFD data， Extreme Gradient Boosting （XGBoost） surrogate models were trained for Nu and Δp. The trained models were then coupled with the Non-dominated Sorting Genetic Algorithm II （NSGAII） to perform multi-objective optimization， and the entropy-weighted technique for order preference by similarity to ideal solution （TOPSIS） was employed to determine the best compromise solution.Results and DiscussionsUnivariate analysis reveals that R1， R2， and α all have significant influences on the thermal-hydraulic performance. Increasing R1 intensifies the flow separation and reattachment and enlarges the recirculation zone. Consequently， the heat transfer performance （h） increases rapidly. However， once R1 exceeds a certain level， the increase in h becomes much smaller than the increase in frictional resistance （f）， resulting in a turning point in the comprehensive performance. Both h and f increase rapidly with an increase in R2； beyond a certain threshold， further increases in R2， cause the trends of h and the performance evaluation criteria （PEC） gradually flatten out. Additionally， h and f show a tendency to increase and then decreasing with the increase of α. The XGBoost surrogate model reproduces the CFD results with high accuracy. The maximum deviations are only 0.44% for Nu and 3.31% for Δp， while the coefficients of determination （R²） reach 0.999 6 and0.998 2， with root mean square errors of 2.94 and 6.42， respectively. Fourteen nondominated solutions were obtained on the Pareto front. The highest ranked compromise solution selected by entropy-weighted TOPSIS corresponds to R1=2.8 mm， R2=0.6 mm， and α=47°. Further CFD simulations over Re=5 000-10 000 confirm that the optimized structure had superior overall heat transfer performance.ConclusionsThe dimpled plate with reverse-side protrusions provides an effective passive strategy for enhancing air-side heat transfer in parallel-plate channels. However， maximizing thermal-hydraulic performance requires a rational combination of large dimple depth， small dimple depth， and inclination angle， rather than merely increasing geometric disturbances. The XGBoost， NSGAII， and TOPSIS frameworks provides a reliable and efficient approach for the multi-objective design of enhanced heat transfer surfaces. For the present channel， the optimized geometry achieves a PEC of approximately 1.55 under equal pumping power over the entire investigated Re range， indicating substantial comprehensive performance improvements， promising application potential in battery thermal management， chip cooling， and other compact forced-air cooling devices.关键词：dimple;heat transfer enhancement;XGBoost;multi-objective optimization14|36|0更新时间：2026-06-29
- 摘要：Driven by the dual impetus of the global “dual-carbon” goal and the imperative for urban thermal environment governance， radiative cooling technology has emerged as a research frontier in the realm of green cooling， owing to its distinctive merits of zero energy consumption and zero emissions. In contrast to existing reviews that focus on traditional systems， such as photonic crystals， metamaterials， and petroleum-based polymers， this review considers biomass-based materials as the exclusive core and systematically summarizes the migration paths and design principles of three classic optical structures （multilayer， porous， and random media） to renewable biomass systems. It clarifies the intrinsic photothermal regulation mechanisms， fabrication processes， and cooling performance of typical materials， including cellulose， collagen， and silk fibroin； covers three application scenarios （energy-efficient buildings， human thermal management， and photovoltaic devices）； and extracts the key bottlenecks from spectral regulation precision， environmental stability， and large-scale preparation. This review fills a gap in exclusive reviews on biomass-based radiative cooling， providing dedicated theoretical support and practical references for the rational design and engineering applications of such green materials.关键词：biomass-based radiative cooling materials;radiative cooling;structural design;photothermal regulation26|62|0更新时间：2026-06-17
- 摘要：Effective thermal management is essential for improving the performance of lithium battery packs operating under low-temperature conditions in cold environments. In the present study， sodium sulfate decahydrate （SSD） was used as the base material， and expanded graphite （EG） with a mass fraction of 2%-12% was incorporated to address issues such as material leakage， phase separation， and low thermal conductivity. After considering the leakage， phase-change material sedimentation， thermal conductivity， and latent heat， a composite phase change material with 10% EG filled into the SSD was selected. A low-temperature experimental platform was employed to simulate the thermal management performance of batteries in cold regions. The results show that the thermal conductivity of the 10% EG-SSD composite is 2.093 W/（m·K）， with a supercooling degree of 17.01 ℃， meeting the requirements for temperatures below 15 ℃. System tests reveal that when the rig filled with the composite is at 5 ℃， the battery temperature remains above 15 ℃ for 2.77 times longer than that without the composite， while the battery discharge power increases by 7.53%， and the discharge time extends by 28%. Furthermore， the charging efficiency is improved by 7.55% and 13.65%， respectively. Under simulated summer car vibration conditions， the 10% EG-SSD can retrieve low subcooling heat release to ensure normal operation of the phase-change cycles.关键词：hydrated salt;supercooling;wide temperature range;battery thermal management20|65|0更新时间：2026-06-17
- 摘要：This study systematically investigated the cooling efficacy and influencing factors of radiative cooling films across different attachment positions on photovoltaic modules under varying weather conditions by establishing a thermoelectric coupling model for integrated photovoltaic module-radiative cooling film assemblies and conducting numerical simulations. These findings indicate that while attaching the cooling film to the rear surface of the PV module yields a slightly lower temperature reduction than the front-side attachment， it avoids power losses caused by obstructing front-side irradiation， resulting in superior overall electrical performance. This configuration achieves an average temperature reduction of 4.55 °C and a power increase of 3.7%. However， under ideal conditions， if the cooling film exhibits high transmittance in the visible spectrum and high reflectance in the near-infrared spectrum， front-side application achieves more pronounced cooling （9.59 °C） and power enhancement （7.83%）. Under varying weather conditions， the radiative cooling film demonstrates optimal cooling performance during sunny summer days. Conversely， under low-temperature， low-irradiance conditions such as overcast winter days， the thermal resistance effect increases the module temperatures. Furthermore， irradiance and ambient temperature exhibit positive correlations with cooling efficiency， whereas wind speed shows a negative correlation. Among these factors， the irradiance exerts the most significant influence on the cooling performance of radiative cooling films.关键词：radiative cooling;photovoltaic modules;thermal management;thermoelectric coupling21|47|0更新时间：2026-06-17
- 摘要：SignificanceWith the growing popularity of wireless sensors and wearable electronic devices in the IoT， the demand for in situ self-powered and flexible cooling technology has increased significantly. Flexible thermoelectric devices， capable of conforming intimately to curved heat sources， such as the human body， offer a unique solution by converting low-grade thermal energy from non-planar surfaces into electricity or localized cooling. These capabilities provide distinct advantages in applications such as self-powered wearable systems and thermal management of flexible electronics. The core strategy for realizing flexible thermoelectric devices involves integrating flexible thermoelectric materials or fabricating them into thin-film structures. Limited by materials and processing techniques， the first reported flexible thermoelectric device was not achieved until 2001， when a team from the Dresden University of Technology fabricated 50 pairs of 10-μm-thick antimony （p-type） and bismuth （n-type） strips embedded in a flexible epoxy resin membrane. The device generated an output voltage of approximately 0.25 V under a temperature difference of 30 K. Current research on flexible thermodynamic devices can be broadly categorized into three main types： （i） high-performance flexible organic thermoelectric devices， （ii） thin-film-based flexible inorganic thermoelectric devices， and （iii） hybrid devices integrating rigid thermoelectric materials with flexible substrates. Over the past decade， flexible thermoelectric devices have achieved significant progress. For example， the device generated a maximum output power of 1.6 mW and maintained a temperature reduction of approximately 10 ℃ on skin， accelerating progress toward the practical application of flexible thermoelectric technologies.ProgressThis review considers the flexible topological scheme of thermoelectric devices as the main focus and systematically examines studies published over the past decade. A dimensionless characteristic length L/d was introduced for the thermoelectric arm， and its correlation with the figure of merit （ZT） of the material was discussed. One-dimensional fiber-based devices primarily fall within the range of L/d>10， whereas two-dimensional film-like devices typically exhibited L/d<0.1. Three-dimensional bulk devices generally exhibited L/d values of 0.1-10. Based on these findings， a classification framework for flexible thermoelectric devices was proposed according to the range of L/d. Meanwhile， one-dimensional fibrous devices demonstrated the best flexibility and wearing comfort， with normalized power density is only 0.86 μW/（cm2·K2）. Two-dimensional film-like devices can be further categorized into thin-film， thick-film， and folding-type configurations， with maximum power density reaching 30 μW/（cm2·K2）. Three-dimensional bulk devices achieved a steady output power of 1.6 μW on skin， which is sufficient to power common sensors and wearable devices， demonstrating strong potential for practical engineering applications. Flexible cooling devices， however， remain in the early stages of development， and the maximum temperature reduction on skin can reach 10 ℃.Conclusion and Prospect However， several bottlenecks in flexible thermoelectric devices must still be addressed. This review proposes the following directions for future optimization： （i） Developing three-dimensionally integrated device architectures， such as folding， curling， and multilayer stacking. （ii） constructing encapsulation structures with the ability to guide heat flow by directing it through the thermoelectric arms in a specific direction. （iii） selecting fatigue-resistant materials， such as flexible polyimides or silicone elastomers for encapsulation and designing stress-buffering structures to improve long-term operational reliability. （iv） advancing biomimetic designs in which the structure matches the Young's modulus of human skin and enhances moisture permeability， avoiding sudden and significant temperature drops in TEC， （v） improving performance evaluation system by considering key parameters， such as cooling capacity and coefficient of performance （COP）， and developing accurate test methods and relevant standards （vi） integrating devices with efficient power management circuits and low-power energy storage units to support the stable operation of practical electronic devices.关键词：flexible thermoelectric devices;wearable devices;flexible topology scheme;power generation performance;cooling performance32|95|0更新时间：2026-06-16
- 摘要：A liquid-separation condenser consists of a vapor-liquid separation unit and heat-exchange tubes， which are strongly coupled. The separation performance governs the heat transfer and flow behavior in the tubes， while the pressure drop across the tubes serves as the primary driving force for separation. However， existing studies have yet to account for this coupling. This study proposes a co-simulation model that couples a three-dimensional computational fluid dynamics （CFD） model of the header-orifice separation unit with a one-dimensional model of heat-transfer tubes by accounting for the mutual influence between the separation effect and tube-side pressure drop. The local and overall performances of the liquid-separation microchannel condenser （LMC） is obtained. A comparison with a conventional microchannel condenser （CMC） is conducted to reveal the mechanism of the effects of vapor-liquid separation on heat transfer performance. The results show that the predictions of the co-simulation model are in agreement with the experimental data. Although the vapor-liquid separation efficiency of the LMC is only 36.2%， the overall performance of the LMC is improved by 16.6% compared with that of the CMC. Moreover， the decreased heat-transfer coefficient in the third tube pass of the LMC leads to a 276.2 W reduction in the heat transfer rate， whereas the pressure drop reduction of the LMC occurs mainly in the second and third tube passes. To fully realize the benefits of liquid-separation condensation， the orifice-baffle structure and the tube pass arrangement must be simultaneously optimized.关键词：phase-separation condensation;Microchannel condenser;co-simulation;liquid-separation efficiency28|56|0更新时间：2026-06-16
- 摘要：To address the challenges associated with visualizing and measuring bubble growth characteristics in the microchannels of two-phase heat exchangers used for flexible electronic thermal management， this study proposes a real-time electrical current measurement method （RTECM） based on the electrical conductivity differences between gas and liquid at the single-bubble scale. Using the visualized variation characteristics of a single bubble in a microchannel undergoing three processes （expansion， elongation， and escape）， a theoretical method was established for deriving the cross-sectional scale and length of the bubble from electrical resistance. The theoretical calculations showed good agreement with the experimental data， with a maximum deviation of 13.4%. Moreover， the RTECM method outperformed the visualization measurement method. The measurement results of the two methods were in good agreement. The results further showed that the RTECM method possesses a high current resolution （10⁻¹¹ A）， overcoming the limitations of high-speed CCD in terms of resolution and shooting angle. By capturing minor changes in electrical current， the minimum bubble size， maximum bubble expansion size， and escape speed in the channel can be measured. Finally， a sensitivity analysis was conducted to evaluate the effects of channel structural dimensions and solution electrical conductivity.关键词：two-phase flow in microchannel;bubble size;electrical current variation;real-time measurement;sensitivity analysis24|58|0更新时间：2026-06-04
- 摘要：The formation mechanism of high-temperature zones in counterflow microchannel heat sinks was investigated through computational fluid dynamics numerical simulations. The following two novel structures were proposed： an outlet top-rib structure and a channel center top-rib structure. The results showed that the inlet effect of edge channels and transverse heat transfer between adjacent channels were the identified as fundamental causes of the parallelogram-shaped high-temperature zones. The uniform bottom rib structure enhanced overall heat transfer； however， the parallelogram-shaped high-temperature zones still persisted. For edge channels， the outlet top rib structure weakened heat transfer at the inlet region and strengthened heat transfer at the outlet region， thereby modifying the morphology of the parallelogram-shaped high-temperature zones and decreasing the maximum wall temperature difference by 33.3%. The channel center top rib structure enhanced heat transfer in the high-temperature zones at the channel center， further reducing the maximum wall temperature difference by 58.3%. Furthermore， it achieved the same average wall temperature as the uniform bottom-rib structure at a low flow rate （1.64 g/s） and outlet top-rib structure at a large flow rate （2 g/s）， while reducingwall temperature difference by 64.8% and 47.2%， and pressure drop by 9.1% and 12.0%， respectively.关键词：microchannel heat sink;chip;fin;temperature difference;counterflow34|56|0更新时间：2026-06-04
- 摘要：This study prepared composite phase-change cold storage materials using carbonized melamine sponge （CMS） and NaCl aqueous solution to address the problems of low energy storage density and large supercooling degree of traditional sodium chloride （NaCl） aqueous solution， and broaden their application in cold thermal energy storage. Fifteen CMS samples were prepared by sintering melamine sponge （MS） at different temperatures and durations in air. The microstructures， thermal conductivities， mechanical properties， and surface wettability of the CMS were systematically characterized. The phase-change characteristics of NaCl aqueous solutions with different concentrations were further explored， and the CMS prepared by the optimal process was compounded with an NaCl aqueous solution to analyze the variation rules of the energy storage density and supercooling degree of the composite materials. The experimental results showed that the CMS sintered at 400 ℃ for 150 minutes exhibited a uniform porous structure and a thermal conductivity of 0.039 41 W/（m·K）， which was 36.7% higher than that of the original MS. Additionally， the CMS exhibited good hydrophilicity， which enabled effective adsorption of the NaCl aqueous solution. Although the high porosity resulted in a slight decrease in its mechanical properties， the material could still satisfy the application requirements of composite cold storage materials. The phase change characteristics test showed that the latent heat of phase change of the NaCl aqueous solution decreased with increasing concentration， while the degree of supercooling initially increased and subsequently stabilized. Compared with pure NaCl aqueous solution， the composite material prepared by CMS sintered at 400 oC for 150 minutes， and NaCl aqueous solution exhibited an energy storage density increase of 6.3%~15.3%， and a significant reduction in supercooling degree of 8.2%~70.1%. The results indicate that CMS can effectively enhance the phase-change energy-storage performance of NaCl aqueous solutions and inhibit supercooling. The prepared composite phase-change cold-storage material demonstrates good application potential， which provides a theoretical basis as well as technical reference for the design and preparation of high-efficiency cold-storage materials.关键词：carbonized melamine sponge;sodium chloride;phase change material;degree of subcooling;porous media33|60|0更新时间：2026-06-04
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