最新刊期
- 摘要：ObjectiveIn arid regions， the low dew-point temperature of ambient air significantly limits the water-harvesting efficiency of conventional condensation-based atmospheric water-harvesting （AWH） systems. To address this limitation， this study proposes a desiccant-wheel-enhanced condensation AWH hybrid system that elevates the dew-point temperature of the incoming air prior to condensation， thereby enhancing the condensation potential. The primary objective of this study was to investigate the performance of three hybrid system configurations featuring different desiccant-wheel partition structures （WFS-1， WFS-2， and WFS-3） under various environmental and operational conditions as well as identify the optimal configuration and operating parameters for efficient water production in arid environments.MethodsA comprehensive mathematical model describing coupled heat and mass-transfer processes in a hybrid system was developed. The model integrates desiccant-wheel dehumidification and regeneration processes with the subsequent cooling condensation process. Numerical simulations were performed to evaluate the effects of key parameters on system performance， including the ambient humidity ratio， ambient temperature， regeneration temperature， and cooling-source temperature. Three system configurations—WFS-1， WFS-2， and WFS-3—were compared. Performance metrics included water harvesting rate （WHR， kg/h） and water harvesting efficiency （WHE， kg/（kW·h））. All simulations were conducted under steady-state assumptions， and model accuracy was validated against experimental data from the literature.Results and DiscussionThe simulation results revealed several key findings. First， the ambient humidity ratio showed a strong positive correlation with the water yield. When the humidity ratio exceeded 3 g/kg（dry air）， WFS-1 achieved the highest WHR owing to its lower pressure decrease and simpler heat-transfer characteristics. However， under extremely dry conditions （humidity ratio <3 g/kg（dry air））， WFS-3 outperformed the other two configurations owing to its enhanced moisture adsorption efficiency in low-humidity environments.ConclusionThis study demonstrated that integrating a desiccant wheel with condensation-based atmospheric water harvesting is a viable strategy for improving the water yield in arid regions. The hybrid system performance was highly sensitive to the ambient humidity ratio， and ambient， regeneration， and cold-source temperatures. Among the three configurations， WFS-1 is recommended for moderately humid arid conditions （humidity ratio >3 g/kg（dry air））， whereas WFS-3 performs better in extremely dry environments （humidity ratio <3 g/kg（dry air））， and offers superior energy efficiency under high-temperature regeneration conditions. These findings provide theoretical guidance for the design and optimization of energy-efficient atmospheric water-harvesting systems tailored to arid and semiarid regions.关键词：Atmospheric water harvesting;rotary dehumidification;condensation water harvesting;arid regions14|24|0更新时间：2026-09-09
- 摘要：This study develops and experimentally validates a three-dimensional unsteady numerical model of an automotive CO2 scroll compressor （theoretical displacement： 1.272 m³/h） to explore effects of internal leakage on compressor performance. The simulation errors remained within 7.8% of the experimental results. Using this model， the effects of axial clearance and sealing structures were investigated. The results show that the sealing structure significantly suppresses secondary gas heating and reduces the discharge temperature by preventing the leakage of the refrigerant from the high-pressure chamber to the discharge and adjacent working chambers. Under the same axial clearance， incorporating the sealing structure reduced the discharge temperature by 16% and improved the volumetric efficiency by 19.7%. Expanding the axial clearance from 0.01 to 0.03 mm increased the discharge temperature by 13% and reduced the volumetric efficiency by 13.7%， while alleviating the over-compression. Moreover， the seal groove depth significantly impacts the leakage， as the sealing structure changes the radial leakage path. Increasing the groove depth increases both the radial and tangential leakage rates， with the former increasing more sharply. The radial leakage constitutes approximately 80% of the total leakage in the compressor， and its proportion increases with the groove depth. Additionally， the elevated leakage raises the suction chamber pressure， and triggers a backflow at the suction inlet. These insights offer guidelines for leakage control and sealing optimization in CO2 scroll compressors.关键词：CO2 scroll compressor;leakage characteristics;numerical simulation;sealing structure2|0|0更新时间：2026-09-09
- 摘要：ObjectiveOil-free linear compressors employ a narrow clearance between piston and cylinder to achieve noncontact operation， thereby eliminating lubrication-related contamination and mechanical wear. However， the unavoidable clearance leakage reduces the volumetric efficiency and becomes increasingly severe under high-pressure conditions， thereby limiting overall compressor performance. Labyrinth seals have been widely adopted in turbomachinery and reciprocating compressors owing to their excellent leakage-suppression capability. Nevertheless， their application in oil-free linear compressors has rarely been reported， and the influence of cavity geometry on transient leakage characteristics has not been systematically clarified. In this study， a rectangular labyrinth seal was proposed for sealing the piston–cylinder clearance， and the effects of cavity geometry on sealing performance were investigated.MethodA transient computational fluid dynamics （CFD） model was established for an oil-free Oxford-type moving-magnet linear compressor. The numerical model incorporated the compression chamber， piston-cylinder radial clearance， rectangular labyrinth seal， and back chamber， enabling simulation of the transient leakage process throughout one operating cycle. Simulations were performed at pressure ratios of 2， 3， 4， 5， and 6. The characteristic cavity size was first evaluated by assigning identical values of 0.1， 0.2 and 0.4 mm to the cavity width， depth and spacing， respectively. Subsequently， the cavity width， depth， and spacing were varied independently， whereas the remaining parameters were maintained at their reference values. The sealing performance was evaluated using the instantaneous leakage mass-flow rate， net-leakage ratio， and transient pressure， velocity， and refrigerant density distributions. Finally， the optimized labyrinth seal was compared with a conventional smooth-clearance seal under identical operating conditions.Results and DiscussionCavity geometry significantly influenced transient-leakage characteristics. An optimum characteristic cavity size of 0.2 mm was obtained， corresponding to a net-leakage ratio of 0.798%. Independent parametric analyses further indicated that the optimum cavity dimensions were 0.2 mm width， 0.1 mm depth， and 0.2 mm spacing， yielding a minimum net-leakage ratio of 0.668%， which decreased progressively along the leakage path because of successive throttling through adjacent labyrinth cavities. Meanwhile， the refrigerant density exhibited a layered distribution that reversed with the leakage direction during different stages of the compression cycle. The transient velocity field showed that the local high-velocity regions were primarily concentrated within the throttling gaps between adjacent cavities， whereas the low-velocity recirculation zones were maintained inside the cavities throughout the cycle. Compared with the conventional smooth-clearance seal， the proposed labyrinth seal reduced the net-leakage ratio by 46.52% at a pressure ratio of 6. Moreover， leakage suppression became increasingly pronounced as the pressure ratio increased， demonstrating the superior sealing capability of the labyrinth configuration under high-pressure ratio conditions.ConclusionThe proposed rectangular labyrinth seal effectively suppressed clearance leakage while maintaining noncontact piston operation. An appropriate cavity geometry is essential for achieving high sealing performance. The optimized structure provided an effective sealing solution for oil-free linear compressors operating under high-pressure ratio conditions.关键词：valve-controlled linear compressor;labyrinth seal;clearance leakage;numerical simulation;sealing performance5|0|0更新时间：2026-08-20
- 摘要：Continuous deteriorations of thermal environments in subway tunnels induces long-term service problems， which significantly affect their safe and efficient operations. Energy tunnel technology is an effective solution for these problems. However， the existing research has not fully revealed the heat-transfer characteristics of shield-energy tunnels with capillary heat exchangers （CHE） under seepage conditions， thereby restricting the engineering application of this technology. Based on a demonstration project， this study established a three-dimensional thermal-seepage coupling numerical model of shield-subway-energy tunnels with CHE， and analyzed the influences of heat-exchanger operational parameters on the heat transfer performances of energy tunnels under seepage conditions. The results showed that seepage could significantly improve the heat-transfer performance of shield-energy tunnels. When the seepage velocity increased from 0 to 2.3×10-5 m/s， the heat transfer during the heating and cooling seasons increased by 106.77% and 276.00%， respectively. The heat transfer capacity of the CHE loop near the seepage inlet was slightly higher than that farther from the inlet. In addition， the inlet flow velocity and temperature of the CHE significantly affected the heat transfer performance. When the inlet flow velocity increased from 0.06 m/s to 0.12 m/s， the heat transfer capacities during the cooling and heating seasons increased by 89.53% and 72.66%， respectively. When the inlet temperature increases by 6 ℃ during the cooling season and decreased by 6 ℃ during the heating season， the heat transfer capacities increased by 58.80% and 177.01%， respectively. However， increasing the inlet flow velocity of the CHE and the heat-transfer temperature difference led to a decrease in the uniformity of the temperature distribution of the segments. This study provides a theoretical support for the design and application of shield-energy tunnels.关键词：energy tunnels;seepage;capillary heat exchanger;thermal performance;subway11|15|0更新时间：2026-08-20
- 摘要：To address the redundant drying time and over-drying problems of rule-based threshold strategies in heat pump clothes dryers， this paper proposes an automatic dryness judgment method based on multi-dimensional time series feature engineering and ensemble learning. The multi-dimensional time series features were extracted according to the operating characteristics of heat pump systems. By combining weakly supervised label generation with a dual sample-cleaning strategy involving label-purity filtering and out-of-fold prediction， an ensemble learning model integrating XGBoost， LightGBM， and CatBoost was established， and a dual-threshold confidence lock was further introduced to reduce the risk of false dry judgments. The results show that the proposed model achieved a test accuracy of 91.26% and F1 score of 92.17% on the static dataset， and the judgment accuracy of high-confidence samples increased to 96.30% after applying the confidence lock. In International Electrotechnical Commission-load and real-load validation tests， the drying time was reduced by 30.9% and 22.4%， respectively， compared with the rule-based threshold strategy while still satisfying the drying requirements. The proposed method can effectively alleviate redundant drying time and over-drying problems and shows good engineering application potential.关键词：heat pump clothes dryer;automatic dryness judgment;time series feature engineering;ensemble learning;confidence locking7|6|0更新时间：2026-08-17
- 摘要：To address the limited energy efficiency of the CO2 transcritical booster refrigeration system due to insufficient recovery of expansion work， this paper proposes a collaborative optimization scheme of multiple ejectors and parallel compression. An experimental system of a multi-ejector replacing the expansion valve and integrating parallel compressors was built， and the influence of parallel compression on system performance was compared under different ejector combinations. The results show that the liquid ejector plays a key role in the system performance， and the "one liquid ejector with three gas ejectors" mode yields the optimum system performance. Compared with the expansion valve system， the maximum refrigeration capacity and COP of the system without parallel compression increased by 8.4%-11.2% and 15.3%-18.8%， respectively. After the introduction of parallel compression， the maximum refrigeration capacity and COP increased by 0.5%-13.9% and 4.6%-17.7%， and the power consumption decreased by 3.3%-4.3%， providing an experimental basis for the efficient optimization of the CO2 booster refrigeration system.关键词：multiple ejector;transcritical CO2;booster system;parallel compression19|4|0更新时间：2026-08-17
- 摘要：To address the challenge of balancing the pressure-bearing capacity and high-efficiency heat exchanging in emerging solid-state barocaloric refrigeration systems， the present study proposes a composite heat-exchanging structure featuring carbon fiber-wrapped finned tubes and establishes a simulation framework for barocaloric refrigeration systems. Using a highly thermally conductive barocaloric composite of co-crystal material NPG0.75-TMP0.25-20%EG， a simulation framework for barocaloric refrigeration was developed based on a finite element model of multi-physics fields， and the barocaloric phase transition state of the computed micro-element was characterized to solve the adiabatic temperature variation. Compared with a conventional aluminum alloy single tube， the composite finned heat exchange tube reduces the weight and structural heat capacity by 95%， increases the heat exchanging area by 2.5 times， and reduces the thermal resistance by 52%. This could significantly improve the heat exchange efficiency， weaken the negative impact of structural heat capacity on temperature changes， and accelerate the system to reach a steady state. Further investigations into the effects of cycle duration， flow velocity of heat exchange fluid， and operational temperature range reveal that the optimal system coefficient of performance （COP） is achieved under a 10-s cycle period and fluid flow velocity of 0.5 m/s. This research provides the theoretical guidance for heat-exchanger structural design with the enhanced overall mechano-thermal performance and operational optimization of solid-state barocaloric refrigeration systems.关键词：barocaloric refrigeration;multi-physics field simulation;carbon fiber reinforcement;plastic crystal composite10|5|0更新时间：2026-08-17
- 摘要：Electric motors are developing towards high power density and miniaturization， making thermal management increasingly critical. This study investigated the influence mechanisms of key parameters， such as the heat source power， position between evaporator and condenser side， and bending angle， on the heat transfer performance of heat pipe. Moreover， comparative analyses were performed on the prediction performance of five machine learning models： genetic algorithm optimized back propagation neural network （GA-BPNN）， convolutional neural network （CNN）， least squares support vector machine （LSSVM）， random forest （RF）， and extreme gradient boosting （XGBoost）. The results indicate that： the coupled detrimental effects of gravity and bending angle on the capillary wick structure govern the heat transfer performance； under a 90° bending angle at 60-W heat source power， the side arrangement of the condenser above evaporator achieves the best equivalent thermal conductivity， which is 30 times that of the condenser under evaporator. The mean absolute percentage error of XGBoost is 3.72%， coefficient of determination is 0.95， root mean square error only higher than that of the GA-BPNN model， and training time is less than 2 s， demonstrating the best performance among five models. The prediction results of XGBoost model illustrate that different positions and bending angles lead to different dissipation performances. To improve the temperature uniformity in the winding of motor， a heat pipe with 0° bending angle is recommended for the heat dissipation of motor.关键词：motor;heat pipe;equivalent thermal conductivity;machine learning10|7|0更新时间：2026-08-17
- 摘要：With the rapid development of artificial intelligence and high-performance computing， cold-plate liquid cooling technology has gradually become a mainstream solution for satisfying the heat-dissipation demands of high-heat fluxes data centers. This paper describes the triggering mechanisms， impact hazards， and the coupled evolution patterns of typical faults in data center cold-plate liquid cooling systems. The principles and characteristics of direct-detection techniques and inverse-problem fault diagnosis techniques are then summarised based on operational data and outlines the key problems encountered when applying these diagnostic techniques to real-world cold-plate liquid cooling systems. Finally， based on diagnostic experience in the HVAC （heating， ventilation and air conditioning） field， this study concludes the targeted methods for addressing these problems， including semi-supervised learning， few-shot learning， data augmentation， and physics-data fusion. Future research could focus on multi-algorithm fusion， mitigating data imbalance， and enhancing model interpretability and anti-interference capabilities to improve the accuracy， reliability， and engineering applicability of fault identification. The review and synthesis presented in this paper can serve as a reference for both theoretical research and engineering applications in the field of cold-plate liquid-cooling fault diagnosis.关键词：data centers;cold-plate liquid cooling;direct detection;fault diagnosis;machine learning44|18|0更新时间：2026-08-10
- 摘要：Linear compressors eliminate the slider-crank mechanism and facilitate oil-free operations. Self-lubricating opposed-piston linear compressors are suitable for integration into attitude-following heat-pump systems while significantly enhancing the system flow rate. In this study， a dual-motor self-lubricating opposed-piston linear compressor prototype was developed， and a comprehensive test bench was established. Using the R1234yf refrigerant， variable-capacity experiments were conducted to analyze the dynamic responses under series and parallel power supply modes. The results indicate that parallel drive requires a lower voltage than series mode， reducing the voltage differential required to achieve synchronized piston strokes in opposing configurations. During 62 Hz operation， when the supply voltage increased from 120 to 160 V， the series mode maintained， on average， a 0.17 higher power factor and 8.1% greater motor efficiency compared with the parallel mode. Thus， the driving mode selection should consider the specific application requirements.关键词：linear compressor;opposed-piston operation;oil-free lubrication;power supply configuration;dynamic characteristics25|8|0更新时间：2026-08-04
- 摘要：A front-jet-assisted cooling scheme is proposed for single-phase immersion oil-cooled servers to address severe bypass flows， insufficient effective flows inside heat sink channels， and local hotspots. Numerical simulations were performed to investigate the associated flow redistribution and mechanisms for heat-transfer enhancement. The results show that introducing front jets enhanced the coolant momentum and renewal at the heat sink channel entrance through local impingement， stagnation pressurization， and entrainment. In addition， the jet flow ratio primarily governed the enhancement intensity， whereas the number of jet holes assigned to each GPU heat sink primarily affected the coverage range and temperature uniformity. Comprehensive comparison indicates that the case with five jet holes and a jet ratio of 0.8 demonstrated the best overall performance， reducing the maximum GPU temperature from 99.12 ℃ to 82.10 ℃ and the temperature standard deviation from 2.54 ℃ to 0.26 ℃.关键词：single-phase immersion oil cooling;jet assistance;heatsink;flow distribution16|33|0更新时间：2026-07-30
- 摘要：Microchannel heat sinks （MCHS） offer broad application prospects in battery thermal management systems （BTMS） due to their high heat-transfer coefficient （HTC） and compact structures. In response to the stringent requirements for temperature uniformity in power batteries， this study reviews the recent research progress in optimizing temperature uniformity across single-phase and two-phase liquid-cooled microchannel heat exchangers， analyzing the mechanisms of temperature non-uniformity， structural optimization methods， and manufacturing feasibility. The results indicate that the temperature non-uniformity in single-phase liquid-cooled microchannels is caused by the uneven flow distribution among the parallel channels and the gradual heating of the coolant along the flow path. Optimization measures， such as improving inlet and outlet arrangements， enhancing manifold structures， employing biomimetic or topological flow paths， and implementing variable-density disturbance structures， can effectively improve the temperature distribution. For two-phase liquid-cooled microchannels， temperature uniformity is influenced by the flow distribution and bubble behavior， requiring surface modification and special structures to regulate the gas-liquid phase distribution. Comparative analysis reveals that the optimization of single-phase flow focuses on improving the liquid flow distribution and enhancing the downstream heat transfer， whereas the key to two-phase flow optimization lies in controlling the bubble behavior. Moreover， the engineering applications of complex microchannel structures are limited by manufacturing costs， processing precision， and long-term reliability. These findings offer practical guidance for designing temperature-uniform structures in MCHS for BTMS.关键词：microchannel;temperature uniformity;structural optimization;single-phase flow;two-phase flow39|47|0更新时间：2026-07-30
- 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;polymer41|74|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 linearization36|56|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 exchanger50|56|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 control64|179|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 charge61|69|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 CO244|73|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 depressant31|68|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 （
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