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- 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 analysis3|5|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;counterflow3|4|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 media2|3|0更新时间：2026-06-04
- 摘要：In indoor environments， people are often exposed to the non-uniform thermal radiation. Most existing research focuses on changes in human thermal physiological responses and subjective thermal sensations under a single type of thermal radiation， such as solar radiation or infrared radiation. To examine the differences in human thermal responses under solar radiation and infrared radiation conditions， this study conducted separate local thermal exposure experiments involving solar and infrared radiation. Under both testing conditions， skin temperature was measured and thermal sensation votes were collected. Differences in thermal sensitivity across body parts under two radiation conditions were then calculated and analyzed. The results showed that， under the effect of solar radiation， a unit increase in radiation intensity caused skin temperatures at various body parts to increase by 0.01-0.02 ℃， whereas infrared radiation produced a relatively greater increase in skin temperature at the exposed area， with reaches up to 1.0 ℃. The greatest changes in the overall thermal sensation occurred when the chest was stimulated by solar or infrared radiation， exceeding 2.0 scale units. Upon stimulus application to limbs， such as the upper arm， forearm， thigh， and calf， overall thermal sensation changed most under the condition of 400 W/m2 solar radiation， whereas differences in overall thermal sensation were not significant under 200 W/m² solar radiation and 4 W/m² infrared radiation. Under local exposure to solar radiation， thermal sensitivity ranged from high to low in the order of chest， upper arm， forearm， thigh， and calf， whereas under local radiant heat exposure to infrared radiation， thermal sensitivity ranged from high to low in the order of chest， upper arm， calf， thigh， and forearm. These findings provide a reference for more accurate prediction of human thermal responses in radiant heat environments， and for optimizing indoor thermal environments.关键词：radiation heat exposure;indoor human thermal comfort;local and overall thermal sensation;thermal sensitivity4|6|0更新时间：2026-06-04
- 摘要：Grain storage is a critical component of safeguarding national food security. The design of ventilation ducts in traditional granaries often relies heavily on empirical settings， which can easily lead to uneven airflow distribution within the silo and the formation of localized heat and moisture hotspots within the grain bulk. In this study， geometric structural parameters such as the air inlet layout， duct diameter， and perforation ratio in the lateral ventilation system of the granary were investigated， and the perforation ratio was subjected to two distinct optimization treatments， labeled Optimization 1 and Optimization 2. A systematic analysis of temperature and humidity variations and their uniformity within the paddy bulk was conducted by combining simulations and physical measurements guided by specific evaluation metrics. The results indicate that positioning the air inlet at the center of the main duct results in a lower temperature differential within the paddy bulk and superior storage efficacy. When the branch duct diameter was 600 mm with a perforation ratio of 35%， the average temperature differential within the paddy bulk was reduced by 29.1% and 14.3%， respectively， compared with the highest recorded average differentials. The average temperatures of Optimization 1 and Optimization 2 were reduced by 0.136 K and 0.078 K， respectively， compared with the pre-optimization values， and the average relative humidities were reduced by 0.134% and 0.164%， respectively， compared with the pre-optimization state. Optimization 1 demonstrated a more pronounced improvement in the uniformity of temperature and moisture distribution within the paddy. Collectively， these findings provide theoretical guidance for the geometric design of ventilation ducts， thereby enhancing temperature and humidity uniformity， reducing fan energy consumption， and promoting high-quality grain storage.关键词：ventilation ducts;CFD simulation;porosity;thermal-hygroscopic performance10|52|0更新时间：2026-05-21
- 摘要：Constructing micro/nanostructured surfaces to manipulate droplet behavior is an effective approach for enhancing condensation heat transfer. However， existing studies rarely discuss the matching effect of micro- and nano-structures. In this study， three CuO nanosheet-microchannel superhydrophobic surfaces （with identical microstructures and different nanostructures， and vice versa） were used to investigate the condensate droplet dynamics of paired surfaces and the heat transfer enhancement mechanism. The results show that increasing the microstructure parameters promotes droplet coalescence bouncing and reduces the size of pinned droplets， whereas decreasing the nanostructure parameters increases the number of nucleation sites and lowers the critical size of Cassie-state droplets. Synergistic regulation of micro/nano structures enhances both the primary Laplace pressure （FΔp1） and the secondary Laplace pressure （FΔp2）， thereby achieving a smaller critical bouncing diameter and higher bouncing frequency. The condensation heat transfer coefficient was enhanced by 12%-41% at subcooling temperatures of 1-16 K. This method provides new insights into condensation heat transfer enhancement via micro/nano-structure synergy.关键词：dropwise condensation;droplet bouncing;micro/nano-structure synergy;heat transfer enhancement21|47|0更新时间：2026-05-21
- 摘要：To improve the heat transfer efficiency and overall performance of supercritical CO2 （SCO2） gas coolers， a numerical study was conducted on the flow and heat-transfer characteristics of SCO2 in internally ribbed twisted elliptical tubes. The heat transfer enhancement mechanism of the tubes was further analyzed based on the field synergy principle. The pitch （p）， rib height （h）， major semi-axis （a）， and Reynolds number （Re） were used as design variables， and second-order response surface models for the Nusselt number， friction factor， and performance evaluation criterion were established using the response surface methodology （RSM）. Multi-objective optimization was then performed using the non-dominated sorting genetic algorithm II（NSGA-II） to obtain Pareto optimal solutions. The results suggest that the combined effects of the twisted geometry and internal ribs induce sustained secondary flows， enhance fluid mixing， and disrupt the thermal boundary layer， thereby significantly improving the convective heat transfer performance of the SCO2 gas cooler. According to this study， a favorable balance between heat transfer enhancement and flow resistance increase can be achieved when h is 0.5 mm， a ranges from 3.6 to 3.9 mm， and p lies within 50 to 70 mm.关键词：supercritical CO2;gas cooler;internally ribbed twisted elliptical tube;field synergy theory;multi-objective optimization13|77|0更新时间：2026-05-15
- 摘要：Refrigerant leakage from a refrigeration system not only degrades the system performance and increases energy consumption but also aggravates environmental hazards and safety risks because of the high global warming potential or flammability of many refrigerants. Therefore， fast and accurate methods are required to detect and rectify refrigerant leaks. This study focused on a domestic air-conditioning refrigeration system with a cooling capacity of 3.5 kW. Using simulation methods， the dynamic evolution laws of the key node parameters of each component and the system performance parameters under different leakage rates were analyzed quantitatively. Based on the findings， a refrigerant inventory prediction model was developed for the key components. This model， integrated with the operational data， provides a new leakage detection and diagnosis method based on system modeling. This method aims to evaluate the severity of leakage using a small amount of leakage data. The developed refrigerant charge inventory prediction equation maintains the prediction error within ±5% when the leakage rate is below 12%.关键词：refrigerant leakage;refrigerant inventory;refrigeration system;leakage detection43|102|0更新时间：2026-05-06
- 摘要：An experimental setup that uses R290 as the working fluid for the dedicated mechanical subcooling of a transcritical CO₂ heat pump system （DMS） was developed and evaluated in this study. The results were compared with those of the conventional baseline CO2 heat pump system （base）. The results revealed that there is an optimal discharge pressure and subcooling degree for the system. Under the operating conditions of an evaporation temperature of 5 ℃ and supply/return water temperature of 50/30 ℃， the DMS system achieved the maximum coefficient of performance（COP） of 3.89， with the corresponding optimal discharge pressure and subcooling degree being 8.4 MPa and 17.3 ℃， respectively. With an increase in the supply/return water temperature， the maximum COP values of both the DMS and base systems exhibited a gradually decreasing trend. Further， the relative COP improvement rate of the DMS system with respect to the base system increased progressively， and the corresponding optimal discharge pressure increased gradually for both systems. The COP of the DMS system remained consistently higher than that of the base system， whereas the optimal discharge pressure was consistently lower than that of the base system. As the supply/return water temperature was increased from 50/30 ℃ to 58/38 ℃， the COP improvement rate increased from 9.6% to 16.7%. Additionally， the power consumption ratio of the R290 compressor to that of the CO2 compressor exhibited an increasing trend， rising from 21.0% to 27.7%. This study provides an experimental reference for enhancing the energy efficiency of CO2 heat pump systems.关键词：transcritical CO2;heat pump;Dedicated mechanical subcooling;R29071|91|0更新时间：2026-05-06
- 摘要：The drying of agricultural products is a core aspect of post-harvest agricultural processing. Traditional drying techniques suffer from certain limitations， such as a low efficiency， high energy consumption， and poor quality， which make them difficult to adapt to the needs of green agricultural development and the "dual carbon" goals. Air-source heat pump drying technology， which recovers waste heat through the reverse Carnot cycle， offers advantages such as a high energy utilization efficiency， precise control over temperature and humidity， and superior product quality， which render it an ideal alternative to traditional drying methods. This article outlines the latest research progress of air-source heat pumps in the field of agricultural product drying， focusing on analyzing research outcomes in terms of the operating principles of the heat pump drying system， system structure optimization， integrated multi-technology drying， low-GWP（Global Warming Potential） refrigerant substitution， and intelligent operational control strategies. The aim is to provide a reference for the large-scale promotion and application of this technology.关键词：air-source heat pump;drying;multi-technology integration;agricultural products59|113|0更新时间：2026-05-06
- 摘要：Accurately balancing numerical stability and resolution remains a major challenge in compressible multiphase flows where shocks， contact discontinuities， and phase interfaces coexist. To address this issue， a nonlinear local entropy-viscosity-based adaptive interface-capturing algorithm is proposed. By constructing a generalized entropy function that incorporates the physical characteristics of phase interfaces and coupling it with a multi-channel discontinuity sensing mechanism， the proposed method achieves unified identification and classification of shocks， contact discontinuities， and phase interfaces. Furthermore， a nonlinear adaptive allocation strategy of local entropy viscosity is introduced， in conjunction with directional interface compression， an energy-consistent surface tension-phase change coupling model， and a dynamic adaptive parameter adjustment technique. This framework significantly enhances interface resolution while maintaining numerical robustness. A transcritical CO2 ejector flow is selected as a representative test case， in which numerical simulations involving phase change， shock/interface interactions， and nonequilibrium thermodynamic processes are performed. The results demonstrate that the proposed algorithm can clearly capture multiscale flow structures， with the interface thickness consistently maintained within 2-3 grid cells. The mass and energy conservation errors are both below 1%， indicating superior accuracy and reliability in complex multiphase flow fields characterized by strong gradients and multi-physics coupling. The proposed method therefore provides a generally applicable high-resolution numerical tool for multiphase flow simulations in practical engineering applications.关键词：compressible multiphase flow;computational fluid dynamics;interface capturing;entropy viscosity;ejector37|102|0更新时间：2026-05-06
- 摘要：In this study， potassium aluminum sulfate dodecahydrate （KAl（SO4）2·12H2O， PASD） was selected as the thermal storage material to achieve efficient thermal storage in medium-to-low temperature ranges. To overcome its drawbacks， such as its high phase transition temperature， significant supercooling， and poor thermal conductivity， a synergistic modification strategy of "eutectic modification-nucleation temperature adjustment-thermal conductivity enhancement" was employed to successfully obtain a high-performance composite phase-change material. Seven potential eutectic components were screened， and potassium nitrate （KNO3） was found to form a stable eutectic system with PASD. At a KNO3 mass fraction of 16%， the phase transition temperature decreased from 92.5 to 77.4 ℃， whereas the latent heat value remained at 248.9 J/g， and the supercooling was reduced to 6.03 ℃. Mechanistic studies revealed that the introduction of K⁺ effectively lowered the energy barrier for crystal melting by weakening the hydration of ［Al（H₂O）₆］³⁺ complex ions. Furthermore， the addition of magnesium sulfate heptahydrate （MSH） at 2% mass fraction as a lattice-matched nucleating agent induced heterogeneous nucleation owing to the similar orthorhombic crystal structures of MSH and PASD， nearly eliminating supercooling （i.e.， supercooling approached 0 ℃） and fine-tuning the phase transition temperature to 75.8 ℃. Finally， 200-mesh graphite powder （GP200） was used at 5% mass fraction as a thermal conductivity-enhancing phase to construct an efficient thermal network， increasing the thermal conductivity of the composite to 1.215 W/（m·K）， achieving 217% improvement over that of the base material， while maintaining a high latent heat of 219.0 J/g. This study provides a theoretical basis for the modification and preparation of high-performance hydrated inorganic salt-based phase-change materials， demonstrating their broad application prospects in solar thermal utilization and industrial waste heat recovery.关键词：potassium aluminum sulfate dodecahydrate;eutectic phase change material;inhibited subcooling;heat conduction enhancement;thermal energy storage53|94|0更新时间：2026-05-06
- 摘要：ObjectiveTo address the demand for high-efficiency heat dissipation in railway transportation and aerospace equipment under variable gravity environments， we systematically investigated the flow boiling heat transfer characteristics of water-glycol mixtures in microchannels and developed data-driven predictive models. Although microchannel flow boiling offers a compact cooling solution， its characteristics under variable gravity are not well understood， and traditional empirical correlations lack prediction accuracy. In this study， we aimed to fill this gap and provide a theoretical basis for optimizing cooling systems for both railway and aerospace applications.MethodsBoth experimental and machine-learning approaches were employed to evaluate flow boiling heat transfer performance. A variable gravity experimental platform based on a centrifugal rotating table was established， capable of simulating gravity environments from 1.00g to 3.16g. The experimental system featured closed-loop circulation with a 200 mm-long， 2 mm-inner-diameter copper microchannel test section. Experiments were conducted across mass fluxes of 50-500 kg/（m2·s）， heat fluxes of 100-800 kW/m2， system pressures of 0.1-0.3 MPa， and inlet subcoolings of 10-30 ℃. T-type thermocouples with ±0.1 ℃ accuracy were used for temperature measurements， while pressure transducers and differential pressure sensors monitored system pressures. Three machine learning algorithms—Random Forest （RF）， Support Vector Machine （SVM）， and Extreme Gradient Boosting （XGBoost）—were developed using 80% training and 20% testing data splits with 5-fold cross-validation for hyperparameter optimization.Results and DiscussionsThe results demonstrate significant gravity-induced enhancement of flow boiling heat transfer. As gravity increased from 1.00g to 3.16g， the heat transfer coefficient （HTC） improved by 60%-80%， while the critical heat flux （CHF） increased by 20%-35%. In the region of low vapor quality （x<0.3）， gravity enhancement reduced bubble departure diameter according to the relationship Db ∝ g-0.5， leading to increased departure frequency and enhanced microlayer evaporation. In the medium quality region （0.3<x<0.7）， gravity intensification resulted in thinner and more uniform liquid films， with peak HTC values reaching 23 000 W/（m2·K） at 3.16g compared to 14 100 W/（m2·K） at 1.00g. In the high-quality region （x>0.7）， hypergravity delayed the onset from x=0.75 to x=0.8. A comparison with ten classical correlations showed that traditional models exhibit large prediction errors under variable gravity， with the best-performing Fang model achieving only a 9.6% mean absolute error （MAE）. In contrast， the XGBoost model achieves an MAE of 3.1% across all gravity conditions， with particularly superior performance at 3.16g （MAE=3.35%） compared to the Fang model （MAE=18.61%）.ConclusionsThis study confirms that gravity is a critical factor in flow boiling heat transfer， significantly enhancing both HTC and CHF through mechanisms such as bubble dynamic optimization and liquid film redistribution. The XGBoost machine-learning model demonstrates superior accuracy in predicting heat transfer performance under variable gravity compared to traditional methods. These findings provide a crucial theoretical basis for the optimal design of cooling systems for railway-vehicle-mounted aerospace airborne equipment that operate in complex gravitational environments.关键词：variable gravity environment;micro-channels;boiling heat transfer;critical heat flux;machine learning71|153|0更新时间：2026-04-28
- 摘要：We investigated the quality changes of ready-to-eat pomegranate arils during storage at 5， 15， 25， and 35 ℃. The kinetic parameters of each quality index were fitted using quality degradation kinetic equations， and a shelf life prediction model was developed by integrating the fitting results with the Arrhenius equation. The results demonstrated that the anthocyanin content exhibited an optimal fit with the first-order kinetic model， exhibiting the highest fitting accuracy. A first-order kinetic model with anthocyanin content as the characteristic index was subsequently combined with the Arrhenius equation to construct a shelf-life prediction model. Validation experiments revealed that the mean absolute error between the predicted and actual values was less than 10%， confirming the high accuracy and reliability of the model. This model can effectively predict the shelf life of pomegranate arils over the temperature range of 5-35 ℃， providing theoretical support and methodological guidance for quality maintenance during the circulation and marketing of the product.关键词：ready-to-eat;pomegranate arils;shelf temperatures;shelf life prediction model25|135|0更新时间：2026-04-27
- 摘要：Against the backdrop of the "dual carbon" goals， in this study we aimed to achieve efficient recovery and reuse of low-grade waste heat generated by high-voltage direct current （HVDC） converter valves. Using R515b as the system refrigerant， thermodynamic models and economic models were established. Through experimental testing， the thermodynamic performance variations and economic analysis of evaporative compression heat pumps versus ejector compression heat pumps were compared at different evaporation and condensation temperatures. The results indicate that the COP of the injection compression heat pump was， on average， 8.75% higher than that of the vapor compression heat pump， with the compressor power consumption reduced by 4.78% and the system heating capacity increased by 3.50%. The total friction losses in the injection compression heat pump were primarily concentrated in the condenser and injector， accounting for 32.6% and 27%， respectively. Economically， the net present value of the injection compression heat pump system increased by approximately 10.9% compared to traditional systems， with a dynamic payback period of 4.08 years. The results show that injection compression heat pumps effectively recover expansion losses， enhance the system energy efficiency and economic performance， and provide an efficient and economical solution for recovering waste heat from inverter valves.关键词：converter valve;waste heat utilization;ejector compression heat pump;heating system32|101|0更新时间：2026-04-27
- 摘要：Condensers， a critical component in refrigeration and heat pump systems， require rapid and accurate performance prediction， which is crucial for system selection and design optimization. Conventional condenser performance evaluation methods， such as computational fluid dynamics simulations and experimental testing， suffer from computational inefficiency and prolonged cycle times. To address their technical limitations， this study developed a synergistic optimization framework integrating genetic algorithms with the simulation modes of the condenser. This approach refined the heat transfer correlations in the single-phase region to enhance the predictive accuracy of the model. The results show that under this optimization method， the average absolute errors in the degree of under subcooling for the plate and finned tube condensers are 1.83 ℃ and 2.23 ℃， respectively. In addition， validation results based on 32 sets of experimental data covering a wide range of operating conditions showed that the average relative errors for both the heat transfer capacity and outlet temperature of the refrigerant were maintained within 5%. This method improved the prediction accuracy of simulation models to some extent， providing effective technical support for the rapid simulation and engineering applications of refrigeration systems.关键词：condenser;thermodynamic model;genetic algorithm;fast prediction42|245|0更新时间：2026-04-24
- 摘要：To investigate the heating performance characteristics of R290 refrigerants in electric vehicle compressors under low-temperature conditions， a comprehensive performance testing system for electric vehicle air-conditioning compressors was established. The variation patterns of power consumption， heating capacity， isentropic/volumetric efficiency， COP， oil circulation rate， and discharge temperature of R290 compressors under low-temperature operating conditions were investigated. The results demonstrate that power consumption and heating capacity increase linearly with rotational speed， with heating capacity decreasing by 13.6%-15.3% for every 5 ℃ reduction in evaporation temperature； isentropic efficiency decreases by 6.2%-9.3% with increasing speed and is more significantly affected by evaporation temperature than by condensing temperature； volumetric efficiency initially increases and then decreases， dropping by 3.5%-4.9% for every 10 ℃ decrease in evaporation temperature and only 0.4%-1.2% for every 10 ℃ increase in condensing temperature； COP decreases with rotational speed， with reductions of approximately 0.15-0.40 and 0.25-0.45 every 5 ℃ decrease in evaporation temperature and every 10 ℃ increase in condensing temperature， respectively； oil circulation rate increases monotonically with speed， being significantly influenced by evaporation temperature while being less affected by condensing temperature； and discharge temperature rises with increasing speed， although the temperature rise induced by speed variation is considerably smaller than that caused by thermal operating condition changes. In this study， we demonstrate that R290 compressors maintain satisfactory heating performance under low-temperature conditions， while validating the feasibility of R290 as an environmentally friendly refrigerant for electric-vehicle air conditioning systems.关键词：R290;compressor;worst cold case;heating performance32|99|0更新时间：2026-04-24
- 摘要：In this study， we analyzed the flow-boiling heat transfer behavior of a copper microchannel heat sink with a high geometric aspect ratio of 18. An experimental platform was established to systematically evaluate the thermohydraulic response and heat dissipation capability under two heating regimes： continuous and intermittent. In the continuous mode with a heat flux of 300 W/cm² and in the intermittent mode with 750 W/cm² for 90 s， the heat sink successfully maintained the heat-source surface temperature below 75 ℃， while the inlet-outlet pressure drop remained around 18 kPa， indicating excellent two-phase thermal and hydraulic performance. In addition， the flow rate and microchannel pressure drop exhibited a strong positive correlation.关键词：thermal management;heating modes;high aspect ratio microchannels;flow boiling heat transfer39|98|0更新时间：2026-04-24
- 摘要：Refrigerant hydrates have potential applications in air-conditioning systems as phase-change cold-storage materials. However， refrigerants are insoluble in water， the nucleation of hydrates in static systems is slow， and the actual cold storage density is low. Surfactants can improve the refrigerant hydrate formation. In this study， fatty acid polyoxyethylene esters （LAE-4 and LAE-9） and fatty alcohol polyoxyethylene ethers （AEO-4 and AEO-9） were used to accelerate the hydrate formation. It was found that the amount of surfactant added affected the hydrate formation. The hydrate-formation induction time with a mass fraction of 2.5% AEO-9 was the shortest （63 min）. Hydrate exhibited the largest cold storage density （246.10 kJ/kg） and its growth rate reached 4.47 kJ/（kg·min） when the mass fraction of AEO-9 added was 2.5%. Surfactants with short hydrophilicities caused the droplets of the emulsion to become large and stratified， whereas surfactants with long hydrophilicities improved the stability of the emulsions. The hydrophobic ester bonds in LAE-9 promoted rapid hydrate formation. Hydrate showed a “memory” effect. There was no evident induction time for hydrate reformation. The stability of emulsions played a pivotal role in hydrate formation. The LAE-9 emulsion system exhibited the best stability in the hydrate formation/dissociation cycle.关键词：hydrate;surfactant;Induction time;cold storage;cycle stability18|77|0更新时间：2026-04-24
- 摘要：For an office building in Zhengzhou， the ground-source heat pump （GSHP） system meets only the heating demand， cannot provide cooling， and its long-term operation leads to soil thermal imbalance and performance degradation. Based on measured data， we first verified the accuracy of the TRNSYS dynamic model， providing a reliable basis for subsequent operational analysis and control strategy research. On this basis， the operation process of a single GSHP system was analyzed， an air-source-ground-source heat pump （ASHP-GSHP） coupling scheme was proposed， and a hybrid PSO-GPS algorithm was used to optimize a dual-threshold control strategy with the goals of system economy and soil thermal balance. The results show that under the temperature control strategy， the annual average system COP remained basically stable at about 3.24 over the 10-year operating period， with a cumulative soil temperature rise of 0.35 °C； under the load control strategy， the annual average system COP remained basically stable at about 3.05， with a cumulative soil temperature rise of 0.38 ℃， and the economic performance was the best， with a payback period of about 4.26 years. Compared with the original heating-only system， in which the COP declined and the soil temperature dropped by 7.47 ℃， the coupling scheme effectively improves system efficiency， maintains soil thermal balance， and reduces CO₂ emissions by approximately 11 000 kg annually. This study provides a reference for the optimal design and efficient operation of cooling and heating cogeneration systems in office buildings located in cold regions.关键词：ASHP–GSHP coupling;combined heating and cooling system;operational control logic;PSO–GPS optimization algorithm47|109|0更新时间：2026-04-24
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