最新刊期
- 摘要：ObjectiveWith the rapid increase in the integration level of microsystems， electronic components are continuously developing toward miniaturization， integration and high power， which renders high heat flux density heat dissipation a critical bottleneck restricting the development of high-end electronic devices. Piezoelectric micropumps are regarded as an ideal candidate for lightweight and thin heat dissipation systems owing to their high integration， high power-to-weight ratio and excellent controllability. In this paper， a microchannel heat sink with fence pin-fin walls driven by a piezoelectric pump is proposed. To evaluate the fluid flow and heat dissipation within the heat sink， a three-dimensional numerical modeling was performed， followed by experimental validations. The heat transfer enhancement mechanism of fence pin-fin walls is revealed， and the effects of fin spacing， area fraction and layout region of fence pin-fin walls on the thermal performance of the heat sink are analyzed.MethodsIn this study， numerical simulations of the microchannel heat sink are performed using Fluent software， where a no-slip coupled boundary condition is applied to the fluid-solid interface， mixed boundary conditions are assigned to the top and bottom surfaces of the heat sink， and no-slip adiabatic boundary conditions are adopted for the remaining walls. Grid independence verification is conducted， and the total number of meshes is determined to be approximately 7.56 million. With the Reynolds number of the working fluid ranging from 35～40， the laminar model is adopted for numerical calculation， and the convergence residual criterion is set to 10⁻⁸. Furthermore， experimental tests are implemented to validate the accuracy and reliability of the established numerical model.Results and DiscussionsNumerical results reveal the heat transfer enhancement mechanism of the fence pin-fin walls structure， and clarify the effects of fence pin-fin walls spacing， area fraction and layout region on the thermal performance of microchannel heat sinks. Compared with conventional microchannels with smooth continuous wall， the fence pin-fin walls heat sink with a fin spacing of 0.2 mm reduces pressure drop by 18.87 Pa and increases flow rate by 1.03 mL/h. Such improvements decrease the thermal resistance R by 4.31% and raise the TPF （Thermal performance factor） by 6.45%， indicating that the proposed structure synergistically strengthens flow disturbance and enlarges the heat transfer area. When the fin spacing increases to 1.0 mm， the average Nusselt number
- 摘要：ObjectiveMulti-zone absorption heat exchanger （AHE） units integrate multiple AHE modules sharing a primary water circuit while serving independent secondary heating zones， thereby combining large-temperature-difference heat transfer with zone-specific heating. However， field operating data and an understanding of zone regulation characteristics remain scarce. This study aims to experimentally investigate the operational performance and independent zone regulation capability of dual-zone AHE units in actual district heating projects.MethodsField tests were conducted on two dual-zone AHE units serving two residential districts （Community A and Community B） in a city in Shanxi Province， China， during the 2025-2026 heating season. Both units use lithium bromide-water （LiBr-H2O） solution as the working pair， with design primary network temperatures of 105/20 ℃ and secondary network temperatures of 47/37 ℃. The rated heating capacities are 16 200 kW for Community A （model AHE162） and 10 800 kW for Community B （model AHE108）. Temperatures at 18 measurement points covering the inlets and outlets of all generators， condensers， evaporators， absorbers， and plate heat exchangers （PHEs） were continuously recorded at 5-min intervals using temperature loggers with an accuracy of ±0.2 ℃ from January 23 to April 1， 2026. Two flow measurement campaigns were performed using clamp-on ultrasonic flow meters with an accuracy of ±0.5%. The coefficient of performance （COP） of each absorption stage and the overall unit effectiveness were evaluated， and a heat balance check was conducted. A temperature-heat flow （T-Q） diagram was constructed for the Community B unit， and the zone regulation characteristics in terms of temperature and load independence were analyzed.Results and DiscussionsThroughout the test period， the primary supply temperature ranged from 55 to 95 ℃， substantially below the design value of 105 ℃. Nevertheless， both units achieved deep cooling of primary water to 20-25 ℃， while secondary supply temperatures remained stable at 35-42 ℃， satisfying space heating demands. The overall effectiveness values were 1.33 for Community A and 1.36 for Community B， and the COP ranged from 0.6 to 0.8， comparable to reported values for conventional dual-stage AHEs （effectiveness of 1.2-1.43）. The heat balance discrepancy was 13.12% for Community B， within the ±15% acceptance threshold， and 23.84% for Community A， which was attributed to large primary water temperature fluctuations during testing. For Community B， the low-zone COP （0.79） was notably higher than the high-zone COP （0.62）. This was explained by the smaller log mean temperature difference （LMTD） of the low-zone solution heat exchanger （2.89 K versus 4.77 K）， indicating more effective internal heat recovery that brought the dilute solution closer to saturation before entering the generator. The T-Q diagram revealed nearly parallel temperature profiles and small vertical gaps between hot and cold streams in the generator and absorber， indicating uniform heat transfer temperature differences， good thermal matching， and low entransy dissipation. Regarding zone regulation， the mean temperature difference between the high- and low-zone secondary returns was 2.01 ℃， whereas that between the secondary supplies was only 0.36 ℃， demonstrating that the two zones maintained nearly identical supply temperatures despite different return conditions. The zone heat loads could be independently adjusted： at Community A the high- and low-zone heat duties were similar （598 kW versus 589 kW）， while at Community B they differed substantially （508 kW versus 852 kW， approximately 68% higher in the low zone）， with the low-zone PHE carrying proportionally more primary flow （16.18 t/h versus 5.98 t/h）， confirming adaptive load allocation between zones.ConclusionsThe dual-zone AHE units maintained high effectiveness and COP under off-design conditions with primary supply temperatures well below the design value， achieving deep primary cooling comparable to conventional single-zone AHEs while simultaneously satisfying the heating demands of two independent zones. The two zones exhibited independent temperature and load regulation， confirming the feasibility and operational flexibility of multi-zone AHE technology for high-rise building district heating.关键词：absorption heat exchanger;multi-zone heating;field test;operational performance;regulation characteristics5|2|0更新时间：2026-11-02
- 摘要：A three-dimensional model of a phase-change sleeve-type ground heat exchanger （PCS-GHE） was developed using COMSOL to investigate the effects of a low PCM volume fraction in a phase-change sleeve on the heat transfer performance and construction cost economics. The heat-transfer performance of the PCS-GHE was improved by optimizing the PCM type， volume dosage， and thermal conductivity. The economic feasibility of construction was evaluated based on an engineering case study. The results show that PCM1， namely the CA-LA-metal thermal conductivity-enhancing material， exhibited a relatively high heat transfer performance， making it more suitable as a phase-change interlayer material for the sleeve. At the end of the third day， when the volume dosage of PCM1 increased from 10.73% to 30.60%， the total thermal resistance of the PCS-GHE increased by approximately 19.5%. The unit heat transfer power and backfill soil temperature decreased by approximately 20.3% and 0.85 ℃， respectively. When the thermal conductivity of PCM1 was increased from 0.6 to 1.8 W/（m·K）， the thermal resistance of the PCM layer and the total thermal resistance of the PCS-GHE decreased by approximately 66.5% and 38.4%， respectively. The unit heat transfer power increases by approximately 42.6%. An increase in the volume dosage of PCM1 led to a higher construction investment for building cooling. In contrast， an increase in PCM thermal conductivity effectively reduces construction investment. When the PCM thermal conductivity was 1.8 W/（m·K）， the construction cost of the PCS-GHE achieved the lowest cost， with the PCM cost and construction investment reduced by 26.3% and 20.5%， respectively.关键词：phase-change sleeve;ground heat exchanger;phase-change material dosage;thermal conductivity;economic analysis4|3|0更新时间：2026-11-02
- 摘要：Against the backdrop of China's "Dual Carbon" goals and the "Maritime Power" strategy， seawater ice slurry， as a highly efficient cold energy carrier， has demonstrated broad application prospects in fields such as cold storage and preservation， seawater desalination， seawater-source heat pumps， and renewable energy integration. However， systematic reviews on its preparation， application， and comprehensive utilization are scarce. This review provides a systematic review and critical assessment of the preparation methods， typical application scenarios， technological advances， and industrialization challenges of seawater ice slurries. In terms of preparation， seawater ice slurry can effectively accommodate renewable energy sources and waste cold resources， including offshore wind power， photovoltaic power， and LNG cold energy. Regarding applications， the cold storage sector is the most mature， with preliminary large-scale deployments in ocean-going fishing vessels. Although cycle optimization has effectively improved system performance in seawater desalination and seawater-source heat pump applications， challenges in control complexity and operational stability remain. The slow industrialization of seawater ice slurry stems primarily from seawater corrosion， insufficient stability in ice slurry preparation and transportation， and a lack of multi-process coupled integration schemes. Building on this analysis， this study proposes a comprehensive utilization strategy that couples seawater ice slurry with renewable energy utilization for the joint production of cooling， fresh water， and salt minerals， providing a new pathway for the large-scale application of this technology in new energy systems.关键词：seawater ice slurry;comprehensive utilization;application scenarios;technical bottleneck28|32|0更新时间：2026-10-28
- 摘要：A one-dimensional real-fluid delayed equilibrium model （DEM） was developed to improve the prediction of mass flow rate， axial pressure， and nonequilibrium flashing in cryogenic throttling flows. The model was validated against the data from Venturis， converging-diverging nozzles， thick orifices， and a self-built orifice test rig. Compared with the homogeneous equilibrium model （HEM）， DEM reduced the root mean squared error of pressure （RMSE） at the Venturi pressure taps from 0.616 to 0.232 kPa. For the nozzle cases， the mean absolute percentage error （MAPE） values of axial pressure and mass flow rate were 5.10% and 6.94%， respectively， while the mass-flow MAPE and RMSE for thick orifices were 11.81% and 14.40%， respectively. The results show that nonequilibrium effects depend strongly on the throttling geometry and flow time scale and are more pronounced in sharp-edged short orifices than in smoothly varying nozzles. Further liquid-nitrogen experiments with 0.5-2.0 mm orifices showed that the mass flow rate increased with the inlet pressure， inlet subcooling， and orifice diameter， approximately following
- 摘要：Faced with the heat dissipation challenges posed by the rapid increase in the computing power of data centers， traditional air cooling can no longer meet their cooling demands because of its limited heat dissipation density. Meanwhile， full immersion liquid cooling is difficult to adopt widely owing to coolant cost， ease of maintenance， and material compatibility. This paper reviews the progress in the application of liquid-air coupled cooling systems in high-power-density data centers and highlights that utilizing cold-plate liquid cooling to efficiently capture the chip heat can significantly reduce the auxiliary air cooling load. It confirms that through the reconstruction of rack airflow fields and optimization of low-flow air cooling， combined with intelligent coordinated control， the power usage effectiveness of the system can be optimized to below 1.15. In the future， the integration of liquid and air cooling systems sharing the same source and waste heat recovery technologies would drive data centers toward zero-carbon goals. This review aims to provide technical guidance for the construction of next-generation data centers that balance cooling efficiency and economic benefits.关键词：data center cooling;liquid-air coupled cooling system;high power density;zero-carbon;heat dissipation31|108|0更新时间：2026-10-24
- 摘要：This paper proposes a high-precision refrigerant charge diagnostic method based on active control， which effectively addresses the shortcomings of traditional passive diagnostic methods， such as low sensitivity to small deviations and susceptibility to interference from system operating conditions. The method actively anchors the core thermodynamic boundary conditions of the system and， based on the principle of mass conservation and heat transfer mechanisms， directionally converts variations in refrigerant charge into changes in liquid-phase retention within the condenser. The condenser outlet subcooling degree is thereby employed as the core characteristic parameter for quantitative diagnosis， and a standardized four-stage diagnostic procedure， including startup， coarse regulation， fine regulation， and measurement is established， with quantitative stability criteria. Cross-validation experiments covering six operating conditions and outdoor temperatures from 20 ℃ to 45 ℃ were conducted in an enthalpy difference laboratory using two multi-split units with nominal cooling capacities of 16 kW and 18 kW. The results demonstrate that， within the charge ratio range of 85%-105%， the subcooling degree exhibits a strictly monotonic increasing trend with respect to refrigerant charge. The subcooling difference between 100% and 90% charge levels remains above 6 °C across all test conditions， and this relationship remains stable across different unit models and outdoor temperatures. The diagnostic model constructed from this relationship can accurately identify refrigerant charge deviations as low as 5%， providing a reliable technical solution for online operational diagnostics and early fault warning in multi-split air-conditioning systems.关键词：multi-split system;refrigerant charge;active control;subcooling degree;fault diagnosis44|91|0更新时间：2026-10-19
- 摘要：A field test was conducted in an office building in Chengdu to evaluate the performance of a fresh-air system integrating electrical energy storage， dew-point evaporative cooling， and mechanical refrigeration under humid summer conditions. A total of 6 589 stable data points over 11 working days were selected based on power， air velocity， operating duration， and air-state variations. The dew-point evaporative cooler reduced the fresh-air temperature from 29.60 ℃ to 23.03 ℃， corresponding to dew-point and wet-bulb effectiveness values of 71.06% and 100.34%， respectively. The enthalpy differences across the evaporative cooling and mechanical cooling sections were 3.20 and 27.39 kJ/kg， respectively. The precooling load fraction was （10.39 ± 3.31）%， and the system coefficient of performance （COP） increased when this ratio exceeded 9.81%. The daily mean COP ranged from 3.16 to 3.49， while its variation after precooling coupling was （0.82 ± 4.17）%. The 30 kW·h battery energy storage unit shifted 11.70 kW·h of load per day， yielding estimated savings of 4.59-5.74 CNY. The evaporative cooling section primarily provided sensible precooling， whereas mechanical refrigeration handled most of the enthalpy load and dehumidification. Adjusting the operation of the evaporative cooling section based on outdoor air conditions can enhance the system's adaptability to operating conditions.关键词：dew-point indirect evaporative cooling;vapor-compression refrigeration;hybrid fresh-air system;precooling load share;battery energy storage29|71|0更新时间：2026-10-19
- 摘要：We creatively proposed a heat pump system （PT/RC-HP） supported by photothermal and radiative cooling to increase the utilization rate of solar equipment and improve the energy efficiency of heat pumps. Using TRNSYS-MATLAB， we jointly simulated the system to assess its heating performance and created mathematical models of photothermal and radiative cooling. The effects of PT-RC area and thermal storage tank volume on system heating performance were systematically investigated， and typical meteorological year data for Changzhou， Jiangsu Province， China， were used to evaluate its long-term heating-season performance. The simulation results indicate that the optimal system configuration comprises a photothermal and radiative cooling collector with an area of 30 m2 coupled with a 2 m³ thermal storage tank. Under this configuration， the system cumulatively collected 3 256.89 kW·h of heat， achieving an average COP of 3.43 for the heat pump. This represents a 10% COP improvement relative to that of conventional air-source heat pumps， corresponding to an energy saving of 160.45 kW·h. The proposed system effectively improves the operational conditions of heat pumps during the heating season， demonstrating both significant energy-saving potential and robust operational stability. Thus， it offers a promising technical pathway for the integration and application of clean energy in building heating systems.关键词：multi-source coupled heat pump;photothermal;radiative cooling;heating performance33|88|0更新时间：2026-10-15
- 摘要：ObjectivePower-to-heat conversion coupled with pit thermal energy storage （PTES） is a potential pathway toward utilizing curtailed photovoltaic （PV） electricity for clean heating. This study evaluated the performance of a PTES system under different power-to-heat configurations driven by curtailed PV power.MethodsA TRNSYS-MATLAB coupled model was developed for three systems： an electrode boiler system （S1）， an air-source heat pump system （S2）， and a combined system （S3）. Two consecutive years of operation were simulated under variable-flow control， while maintaining a constant temperature. The system energy flows， charging/discharging boundaries， water thermal stratification， heat losses， and thermal storage efficiency were analyzed.Results and DiscussionThe differences in heating contribution among the three systems mainly stemmed from the PTES discharge and auxiliary heat supply， with the curtailed-PV heating guarantee fractions reaching 82.9%， 80.7%， and 84.2% in S1， S2， and S3， respectively. Fluctuations in the curtailed PV power were mainly reflected by circulation-flow variations， whereas equipment switching in S3 also caused fluctuations in the charging temperature. The mean MIX numbers during the heating period were 0.276， 0.273， and 0.298 for S1， S2， and S3， respectively， revealing pronounced thermal stratification under the investigated conditions. The sidewall heat loss accounted for a relatively large proportion during the initial operating period， and the top-cover heat loss gradually became dominant as heat accumulated in the surrounding soil. The first-year thermal storage efficiencies were 91.49%， 88.11%， and 88.97% for S1， S2， and S3， respectively.ConclusionsPTES can accommodate the dynamic charging boundaries associated with curtailed-PV power-to-heat conversion and thus effectively contribute to both PV-curtailment utilization and building heating. However， the discrepancy between the steady-state capacity design and the dynamic operating performance indicates that future system sizing should account for hourly curtailed-PV–load matching and practical operating constraints.关键词：curtailed photovoltaic electricity;pit thermal energy storage;thermal stratification;heat loss;thermal storage efficiency18|59|0更新时间：2026-10-09
- 摘要：SignificanceAgainst the backdrop of global carbon peaking and carbon neutrality goals， the building sector faces an urgent demand for low-carbon transformation. Heating， ventilation， and air-conditioning （HVAC） systems account for more than 60% of the building energy consumption， accompanied by a prominent temporal-spatial mismatch between energy supply and demand. Thermal energy storage （TES） technologies， which allow for the storage and release of thermal energy on demand， represent a pivotal solution to mitigate this mismatch and enhance the energy flexibility of buildings. However， the existing literature mainly focuses on the basic classification and conventional applications of TES while lacking a systematic summary of advanced-performance optimization systems and interdisciplinary innovative application schemes in building scenarios. To fill this research gap， the present study conducted a comprehensive review of the development status， application challenges， and optimization pathways of TES technologies in building applications， thereby providing valuable theoretical references for related research and engineering practices.ProgressThis paper elaborates on the classification and working mechanisms of three mainstream TES technologies： sensible heat storage， latent heat storage， and thermochemical storage. Water-based sensible heat storage is widely deployed owing to its technological maturity and low cost； however， it is constrained by its low energy density and considerable space occupation. Latent heat storage utilizing phase-change materials （PCM） features high energy density and a nearly isothermal charging-discharging process， thus emerging as a research hotspot in building energy storage. Thermochemical storage boasts of ultrahigh energy density and negligible heat loss during long-term storage， although most relevant technologies are still in the laboratory research stage.Conclusion and Prospect TES technologies have demonstrated remarkable application value in building energy conservation and power grid demand response， serving as core enablers for the low-carbon transformation of the building sector. Nevertheless， the large-scale engineering deployment of TES is still hindered by multiple bottlenecks： the intrinsically low thermal conductivity of PCMs restricts the heat charge‒discharge rate； the integration adaptability between TES systems and existing building energy systems remains inadequate； and there is a lack of comprehensive evaluation covering full life-cycle economic and environmental benefits.关键词：low-carbon building;thermal energy storage technology;phase-change materials;thermal diode;mobile terminal40|75|0更新时间：2026-10-09
- 摘要：Absorption thermal energy storage can effectively alleviate the temporal and intensity mismatches between renewable energy supply and heating/cooling demands. Working-fluid screening is a key factor affecting the energy storage performance and applicability. In this study， a unified comprehensive evaluation method for working fluids was established to systematically compare three generations of absorbents—conventional inorganic salts， ionic liquids， and deep eutectic solvents—in terms of cooling/heating cycle performance， response rate， feasible operational temperature range， and economic performance. The results showed that H2O-ionic liquids delivered high cycle performance in both cooling and heating modes. In the cooling mode， H2O-［EMIM］［OAc］ achieved an energy storage density （ESD） of 380 kJ/kg and an energy storage efficiency （ESE） of 0.86， whereas in the heating mode， H2O-［EMIM］［EtSO4］ achieved an ESD of 375 kJ/kg and an ESE of 1.65. Conventional H2O-LiBr delivered favorable heat transfer performance， but its feasible operational temperature range was restricted by crystallization. As the heating temperature increased， the minimum charging temperature of each working fluid also increased， imposing a higher requirement on the temperature level of the charging heat source. Ammonia-based working fluids can meet subzero cooling demands. NH3-glyceline achieved an ESD of 227 kJ/kg and an ESE of 1.61 in the heating mode， and maintained a wide operational temperature range. Deep eutectic solvents showed clear advantages in terms of economic performance. At a system lifetime of 15 years， H2O-ethaline showed the lowest levelized cost of storage， i.e.， at USD 0.091/（kW∙h）， which was 36.5% lower than that for H2O-LiBr. These results provide useful guidance for selecting working fluids to be used in absorption thermal energy storage under various application scenarios.关键词：absorption thermal energy storage;working fluid;ionic liquid;deep eutectic solvent;energy storage density26|66|0更新时间：2026-10-09
- 摘要：The high-quality development of the electric-vehicle industry is critical to promoting China's energy revolution and achieving the goals of carbon peaking and carbon neutrality. Currently， climate adaptability of electric vehicles has become a technical bottleneck that restricts the widespread adoption and application of electric vehicles. To address the high energy consumption of air-conditioning systems for electric vehicles in low- and high-temperature environments， which significantly limits their driving range， this study proposes a dual-evaporation temperature heat-pump air-conditioning system. An experimental prototype and a simulation model of the proposed system are developed. Subsequently， the operating characteristics of the proposed system under variable conditions， as well as its energy-saving effectiveness relative to conventional heat-pump air-conditioning systems for electric vehicles， are experimentally and numerically investigated. The results indicate that energy efficiency of the dual-evaporation temperature heat-pump air-conditioning system initially increases and then decreases as the cylinder volume ratio of the dual-cylinder compressor increases. At a cylinder volume ratio of 1.25， energy-saving effect of the dual-evaporation temperature heat-pump air-conditioning system can reach 8.2%-30.2% at low temperatures ranging from -20 ℃ to 0 ℃ and 16.3%-48.3% at high temperatures ranging from 30 ℃ to 42 ℃.关键词：electric vehicle;dual-evaporation temperature;heat-pump air conditioning;waste-heat recovery;graded cooling78|116|0更新时间：2026-09-30
- 摘要：To evaluate the low Global-Warming-Potential （GWP） zeotropic refrigerant R454C in multimode thermal management systems for electric vehicles， an integrated heat pump test bench was developed that combines direct expansion in cabin with a secondary coolant loop to analyze the effects of temperature glide on system performance and cabin outlet-air uniformity. Experiments were conducted under standalone cabin cooling， battery-only cooling， combined cabin-and-battery cooling， and low-temperature heating modes to investigate the effects of refrigerant charge， superheat， frontal air velocity， and compressor speed. The results show that the refrigerant charge of a multimode system should be determined by considering both the overlapping performance plateau ranges of different operating modes and the pressure safety margin， with 1 025 g identified as the recommended charge for the present test bench. Under high-ambient-temperature cooling conditions， enhancing frontal heat rejection exerts a more pronounced effect on system performance， although the benefit exhibits diminishing returns as air velocity increases. In direct-expansion mode， an increase in superheat expands the local dryout and superheated regions. Exaggerated by refrigerant temperature glide and flow maldistribution among parallel circuits， this phenomenon significantly reduces the outlet-air temperature uniformity. Under identical hardware and control boundaries， the COP （coefficient of performance）of R454C at cooling temperatures of 40 ℃-43 ℃ is 13.8%-20.0% higher than that of R134a， while effective low-temperature operation is maintained down to -20 ℃. These results indicate that， for low-GWP refrigerant blends with temperature glide， the optimization of automotive heat pump systems should shift from single-parameter optimization toward coordinated matching of refrigerant charge， superheat， heat transfer capacity， and system heat transfer paths. The findings provide a basis for the system design and control of low-GWP zeotropic refrigerants in electric-vehicle thermal management systems.关键词：electric-vehicle heat pump;R454C;direct expansion;temperature glide;outlet-air temperature uniformity126|159|0更新时间：2026-09-29
- 摘要：ObjectiveThe dynamic carbon emission responsibility factor of electricity （Cr） varies considerably over time because of changes in the power generation mix， system load， and unit operational conditions. Its temporal profile might not coincide with the time-of-use electricity prices defined by fixed periods. As a result， low-price periods are not necessarily the same as low-carbon periods， which might create the conflicts between the economic and low-carbon operation of ice thermal storage systems. This study aims to develop a day-ahead dispatch method that can respond simultaneously to the carbon-responsibility and electricity-price signals. The method is designed to coordinate the operational revenue and carbon-reduction performance under different temporal relationships between the two signals.MethodsAn equivalent charging and discharging power model was firstly developed to elucidate the influence of ice storage operation on the user-side electricity demand. The model considers the charging state of the ice storage tank， the operational characteristics of the dual-mode chiller， and auxiliary equipment power consumption. A linear programming model of multi-objective day-ahead mixed-integer was then established. The two objectives were the incremental electricity cost and incremental carbon emission responsibility caused by the ice storage operation. An economic preference coefficient was introduced to balance the normalized economic and low-carbon objectives. A total of 100 preference coefficients ranging from pure low-carbon strategy to pure economic strategy were evaluated for each Cr scenario. After the duplicate and dominated solutions were removed， the Pareto non-dominated solution sets were obtained. Operational revenue， carbon emission responsibility， and low-carbon matching degree were selected as the performance indicators. The entropy-weighted technique for order preference by similarity to the ideal solution （TOPSIS） was used to evaluate the Pareto solutions and determine the preferred economic preference coefficient. A case study was conducted for an industrial park in Hangzhou using the 2024 time-of-use electricity price and four typical Cr profiles， i.e.， an overall high-carbon profile， a low-carbon low-variation profile， a single-peak profile， and a double-peak profile.Results and DiscussionThe entropy weights and the preferred economic preference coefficient varied markedly with the temporal characteristics of Cr. For Cr1， the weights of carbon emission responsibility and low-carbon matching degree are 0.40 and 0.36， respectively. Regarding Cr3， where high-Cr periods clearly overlap with the midday low-price period， the low-carbon matching degree receives the highest weight of 0.47. The preferred economic preference coefficients for Cr1-Cr4 are 0.27， 0.20， 0.22， and 0.40， with the recommended ranges of 0.15-0.47， 0.08-0.30， 0.14-0.43， and 0.24-0.47， respectively. Dispatch results further show that the economic strategy tends to charge during the low-price but high-Cr periods in Cr1 and Cr3， whereas the preferred multi-objective strategy shifts charging away from these periods. Compared with the low-carbon strategy， operational revenue are increased by 78.5%， 12.7%， 107.7%， and 14.7% for Cr1-Cr4， while 93.9%-98.3% of the carbon-reduction benefit is retained. The carbon-responsibility improvement potential relative to the economic strategy reaches 87.7%-95.8%， with the low-carbon matching degrees of -0.79 to -0.91.ConclusionsThe proposed day-ahead dispatch method can effectively coordinate the economic and low-carbon operation of ice thermal storage systems under the temporally mismatched carbon and price signals. The four Cr scenarios require different economic preference coefficients， namely， 0.27， 0.20， 0.22， and 0.40， confirming that a fixed preference setting cannot adequately represent different carbon-price coupling conditions. Relative to the low-carbon strategy， the preferred multi-objective strategy retains 93.9%-98.3% of the carbon-reduction benefit while increasing the operational revenue by 12.7%-107.7%. Relative to the economic strategy， it achieves 87.7%-95.8% of the available improvement in the carbon emission responsibility. These results demonstrate that scenario-adaptive preference selection can suppress the high-carbon charging induced by low electricity prices and provide a practical basis for the coordinated carbon-energy interaction on the demand side.关键词：ice thermal storage;dynamic carbon emission responsibility factor of electricity;time-of-use electricity price;day-ahead dispatching;multi-objective optimization73|101|0更新时间：2026-09-24
- 摘要：ObjectiveMedium- and high-temperature waste heat is intermittent and fluctuating， resulting in a mismatch between heat supply and demand. Latent heat storage based on phase change materials （PCMs） provides an effective method for high-density thermal energy storage. Lithium nitrate （LiNO3） has a suitable phase change temperature and high phase change enthalpy for waste heat recovery， but its low thermal conductivity limits the volumetric power density. In this study， using LiNO3 as the PCM and expanded graphite （EG） as the material for enhancing thermal conductivity， LiNO3/EG composite phase change materials （CPCMs） were prepared， and their thermophysical properties and heat storage performance were investigated.MethodsLiNO3/EG CPCMs with EG mass fractions of 5%， 10%， 15%， and 20% were prepared via a solvent evaporation method. Fourier transform infrared （FTIR） spectroscopy， X-ray diffraction （XRD）， differential scanning calorimetry （DSC）， transient plane source （TPS）， and thermogravimetric analysis-derivative thermogravimetry （TG-DTG） characterized the chemical compatibility， phase composition， phase change properties， thermal conductivity， and thermostability. A computational fluid dynamics （CFD） analysis of a shell-and-tube latent heat storage unit was conducted to evaluate the heat storage behavior of CPCM85 （85% LiNO3/15% EG） and pure LiNO3 under flue gas heating.Results and DiscussionsFTIR and XRD results showed that no new chemical phases were formed， and LiNO3 was physically confined within the EG porous structure. Increasing EG content improved thermal conductivity but reduced phase change enthalpy. CPCM85 exhibited a phase change temperature of 260.46 ℃， a phase change enthalpy of 291.3 kJ/kg， and a thermal conductivity of 3.53 W/（m·K）， with the thermal conductivity 6.92 times higher than that of pure LiNO3. The residual rate of PCM components increased from 24.05% to 32.81%. The CFD results showed that the melting time decreased from 4 167 s to 2 178 s， and the heat storage rate reached 35 W at 5 000 s， which was 4.93 times that of pure LiNO3.ConclusionsConsidering the thermal conductivity， phase change enthalpy， and thermogravimetric characteristics， CPCM85 exhibited a favorable overall performance and was selected for the simulation， indicating its potential application in medium- and high-temperature waste heat recovery systems.关键词：medium- and high-temperature thermal energy storage;composite phase change materials;expanded graphite;lithium nitrate;thermal conductivity enhancement74|81|0更新时间：2026-09-24
- 摘要：Existing multi-split air conditioning systems fail to provide satisfactory thermal comfort in complex residential operating scenarios. To address this limitation， this study proposes a dynamic superheat-driven adaptive precision temperature control strategy employing a multi-agent reinforcement learning （MARL） algorithm. The strategy accounts for system operational characteristics and room temperature dynamics across three distinct control stages， namely， start-up， rapid cool-down， and steady-state operation， and implements a stage-specific control scheme for electronic expansion valve （EEV） opening and indoor-unit superheat. Experimental validation demonstrates that the prototype incorporating the proposed strategy achieves a cool-down response rate of ≥0.45 ℃/min and a temperature fluctuation of <0.3 ℃. Compared with two conventional control strategies—fixed evaporation temperature and fixed superheat—the proposed strategy exhibits significant advantages in both setpoint attainment time and steady-state stability， with an improvenet of overall cool-down rate by 38.4% and temperature control accuracy by 42.2%.关键词：multi-split air conditioners;precise temperature control;multi-agent reinforcement learning117|140|0更新时间：2026-09-24
- 摘要：ObjectiveR1132（E）/R1234ze（E） is a promising low-GWP binary working fluid， but both components are flammable. Leakage of the fluid during transport or operation may trigger combustion and release highly toxic fluorinated products， posing serious risks to human health and the environment. Therefore， this study aims to investigate the safety of this blended fluid in practical applications.MethodsThis study employs reactive force field （ReaxFF） molecular dynamics and density functional theory （DFT） methods to examine the effects of temperature， oxygen equivalence ratio， component ratio， and water molecules on the oxidative combustion behavior of the blended fluid. The DFT calculations are conducted at the M06-2X/6-311+G（d，p） level using Gaussian 16W to obtain the bond dissociation energies and bond lengths of the two fluids， and the reliability of the CHOSFClN-2014 force field is validated against the DFT results. ReaxFF simulations are performed with LAMMPS on systems containing 200 working fluid molecules together with O2， covering R1132（E）/R1234ze（E） molar ratios of 8∶2-2∶8， oxygen equivalence ratios of 0.5-1.5， and temperatures of 1 000-3 000 K； the effect of water molecules is further examined by introducing them into a specific system. The time evolution of reactants， main products， and key radicals is analyzed.Results and DiscussionsThe results indicate that the oxidative combustion of R1132（E）/R1234ze（E） is initially dominated by pyrolysis， with oxygen gradually participating in the reaction at subsequent stages. Reaction temperature is the dominant factor controlling the system reaction rate： at 2 000 K and above， the reactants are completely consumed within 3 000 ps. Elevated temperatures significantly accelerate initial pyrolysis and promote subsequent oxidative conversion. Oxygen content primarily affects the oxidation depth： the yields of CO and CO2 increase significantly as the oxygen equivalence ratio rises from 0.5 to 1.5， but the initial pyrolysis rate is barely affected. The component ratio regulates the reaction pathway by altering the hydrogen-to-fluorine ratio in the system； HF yield remains constant at about 350 molecules， accounting for over 90% of the total hydrogen in the system， whereas a higher proportion of R1234ze（E） prolongs the complete decomposition time of the mixed working fluid and enhances COF2 formation. Environmental water molecules significantly promote complete carbon oxidation and increase HF yield by thermally dissociating to provide active radicals and capturing fluorinated intermediates.ConclusionsAt the molecular level， it is revealed that R1132（E） preferentially initiates reaction through a self-decomposition pathway， while R1234ze（E） preferentially undergoes C-C bond cleavage to generate ·CF3 and ·C2H2F radicals. These intermediates are subsequently oxidized to CO2 via the COF2/COF pathway and stepwise C-F/C-H dissociation pathways， respectively. This study investigates the combustion reaction mechanism of the binary flammable working fluid R1132（E）/R1234ze（E） at the microscopic scale， providing a theoretical reference for its safe application in refrigeration and air-conditioning systems.关键词：R1132（E）;molecular dynamic simulation;mixed refrigerants;computational chemistry;Safety97|66|0更新时间：2026-09-24
- 摘要：Solution crystallization energy storage can enhance the thermochemical storage density by coupling the solution concentration with solid–liquid phase change. In this study， a honeycomb LiBr-H2O crystallization energy storage system was developed， and a single-cell heat- and mass-transfer model was developed. The experiments were used to study the crystallization evolution， while the simulations examined the effects of heat-source temperature and initial solution mass fraction. A mass-transfer Péclet number was introduced to quantify the competition between the interfacial evaporation and internal diffusion. The crystallization process comprised three stages， i.e.， solution concentration， crystal–liquid coexistence， and crystal dehydration. Increasing the heat-source temperature from 120 ℃ to 140 ℃ raised the peak heat flux from 2.465×104 W/m2 to 3.512×104 W/m2 and the peak mass-transfer flux from 1.680 mol/（m2·s） to 2.572 mol/（m2·s）. Increasing the initial solution mass fraction from 53% to 57% enhanced the mass-transfer flux but reduced the mass-transfer coefficient because higher viscosity limited the liquid-phase diffusion. When the mass-transfer Péclet number exceeded 1， the interfacial evaporation dominated the internal diffusion compensation， promoting LiBr enrichment near the gas–liquid interface and preferential crystallization. These results provide a basis for optimizing the heat and mass transfer in the energy storage units of honeycomb solution crystallization.关键词：honeycomb cell;lithium bromide;solution crystallization;energy storage71|85|0更新时间：2026-09-24
- 摘要：This study proposes a fast-charging and cooling strategy suitable for charging electric vehicles under high ambient temperatures. By jointly regulating the charging current based on cell temperature and state of charge （SOC）， this strategy aims to maximize the charging capacity of cells. A 1P108S battery pack composed of lithium-ion cells with a rated capacity of 119 Ah was used， and the heat generation model for the cell was established through Hybrid Pulse Power Characterization （HPPC） testing. During the charging process， the cooling system was utilized to mitigate battery temperature rise， and the effects of different cooling strategies on charging performance were systematically analyzed. The results indicate that the liquid cooling system achieved optimal heat transfer efficiency when the coolant flow rate was 12 L/min and coolant temperature was 22 ℃. To prevent the cells from overheating， the charging rate was limited when the cell temperature reached 48 ℃. Under the optimized strategy， the maximum battery temperature was 49.2 ℃ and charging duration was 2 654 s. Finally， the numerical model was validated through battery pack charging experiments， with deviations in the maximum temperature and maximum temperature difference both within 5%.关键词：battery thermal management;fast charging strategy;cooling strategy;heat transfer efficiency96|119|0更新时间：2026-09-15
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