最新刊期
卷 46 ， 期 4 ， 2025
- 摘要：Room-temperature magnetic heat pumps, one of the main applications of the magnetocaloric effect near room temperature, offer high efficiency, environmental protection, low noise, and low vibrations. This study discusses the application potential of a cascade magnetic heat pump cycle with a large temperature span by comparing the theoretical magnetic heat pump and refrigeration cycles. The results show that meeting the kilowatt-level heating capacity and achieving a wide temperature span of approximately 30 K in an actual heating scenario poses challenges to room-temperature magnetic heat pumps. The differences in design and application between the room-temperature magnetic heat pump and the existing room-temperature magnetic refrigeration prototypes are discussed, with a focus on magnetocaloric material selection strategies and performance evaluation indices suited for large temperature spans. The comparative analysis of magnetic heat pumps and magnetic refrigeration in this study also helps researchers to clarify the key to the design and application of large temperature span magnetic heat pumps based on existing research on room-temperature magnetic refrigeration. It promotes the comprehension and application of room-temperature magnetic heat pumps.关键词：magnetocaloric effect;Magnetic refrigeration;Magnetic heat pump;Cascade cycle;Magnetocaloric material2|0|0更新时间：2025-08-28
- 摘要：The current greenhouse effect and the "dual-carbon" goal have set off a new wave of refrigerant substitution, requiring new refrigerants to achieve a comprehensive balance between environmental protection, safety and thermal properties. However, there are currently no ideal substitutes for these refrigerants. Most environmentally friendly refrigerants, such as R290, R32, and R1234yf, which have low ozone depletion potential (ODP) and Global Warming Potential (GWP), are flammable and pose safety risks. Identifying suitable flame retardants for environmentally friendly flammable refrigerants has emerged as a crucial focus of current research on refrigerant alternatives. This article provides a recent overview of research progress on the compatibility of flame retardants with flammable refrigerants. The main focus was categorizing the various flame retardants and assessing their efficacy across different flammable substances. It also discusses their performance, effects, mechanisms, and environmental impacts. Furthermore, the article analyzes their potential applications and development trends and recommends flame retardants compatible with flammable substances.关键词：Flammable refrigerants;Flame retardants;Safety;flame retarding properties;research status2|0|0更新时间：2025-08-28
- 摘要：Propane (R290) is a potential refrigerant substitute for household air conditioners. However, its flammability limits its application. In this study, the flammability limits of R290, 2,3,3,3-tetrafluoropropene (R1234yf), trans-1,3,3,3-tetrafluoropropene (R1234ze(E)), R1234ze(E)/R290, and R1234yf/R290 were determined according to the ASHRAE 34-2022 standard. The effects of R1234yf and R1234ze(E) on the flammability of R290 were analyzed, and the inhibiting abilities of R1234yf, R1234ze(E), R32, R13I1, and R134a on the flammability of R290 were compared. In addition, the refrigeration cycle performance of R290 mixtures with different compositions was simulated. The results showed that both R1234yf and R1234ze(E) exhibited limited flame inhibition capabilities for R290. When the mass fractions of R1234yf and R1234ze(E) reached 80%, the lower flammability limit of the mixture increased by approximately 1.0%. The experimental data were correlated using the Le Chatelier model, which resulted in an average absolute deviation of 0.57% between the calculated and experimental results. Compared with R290, the energy efficiency ratio of the two refrigerants and R290 mixture decreased by less than 1%, and the volumetric cooling capacity increased by less than 0.4%. The flame inhibition effect of the refrigerant on R290 decreased in the following order: R13I1>R134a>R32>R1234ze(E)/R1234yf.关键词：refrigerant;flammability limit;propane;2,3,3,3-tetrafluoropropene;trans-1,3,3,3-tetrafluoropropene2|0|0更新时间：2025-08-28
- 摘要：With continuous economic development, the world faces a growing freshwater shortage and energy scarcity crisis. Reducing energy consumption in handling heat and moisture loads in air-conditioning systems and solving the global water crises have become urgent priorities. The dynamic adsorption and desorption properties of adsorbents significantly affect the heat and moisture transfer characteristics of adsorptive atmospheric water-harvesting systems and dehumidifying heat-exchanger air-conditioning systems. In this study, the dynamic adsorption and desorption properties of thermosensitive composites doped with different thermally conductive nanomaterials, such as nano-copper powder, nano-silver powder and nanographene, were investigated, and the theoretical daily water production capacity of the optimal materials was analyzed. The results show that the thermosensitive materials doped with graphene nanopowder have good adsorption/desorption kinetics. Their equilibrium adsorption capacity reaches 2.51 g/g, which is 1.46 times higher than the undoped thermally conductive materials. The desorption within 60 min is 1.17 times higher than undoped thermally conductive materials. In addition, with a cycle time of 3 h and an adsorption-to-desorption time ratio of 2∶1, the thermosensitive material doped with nanographene can achieve a theoretical daily water volume of 7.02 g/(g·d), which is 21% higher than that of the undoped material.关键词：Thermosensitive adsorbents;Heat-conducting material;Adsorption-based dehumidification;Atmospheric water harvesting;Absorption kinetics2|0|0更新时间：2025-08-28
- 摘要：To further study the influence of heat exchanger structures on system performance and overall power consumption in transcritical CO2 heat pump air conditioning systems for high-speed trains to improve performance and reduce power consumption, this study builds a numerical simulation model based on the AMEsim simulation platform. The simulation results show that, in the high-speed train heat pump air conditioning system, the influence of the gas cooler structure on system performance is greater than that of the evaporator structure. In terms of the selection of heat exchanger structure, the optimal structure is that during refrigeration, the outdoor heat exchanger adopts the countercurrent arrangement and the indoor heat exchanger adopts the concurrent arrangement (vice versa for heating). At the rated cooling condition of 35 ℃ ambient temperature, the COP is increased by 20.38% compared to the concurrent arrangement in outdoor heat exchangers, and at a rated heating condition of 7 ℃ ambient temperature, the COP is increased by 68.04% compared to the concurrent arrangement of indoor heat exchangers. Considering both the degree of backflow and fan power consumption, in the "fully heat exchange state", system COP increases with backflow degree, while system COP decreases with backflow degree when the air flow rate is insufficient.关键词：transcritical CO2 heat pump air conditioning;rail vehicles;heat exchanger co-current and counter-current;optimal structure2|0|0更新时间：2025-08-28
- 摘要：Ground-source heat pump (GSHP) systems using composite energy geostructures can efficiently transfer heat to soil and provide a high coefficient of performance (COP) for both cooling and heating, which has broad application prospects for energy saving in buildings. However, groundwater seepage in the soil can significantly affect the heat-transfer performance of a composite energy geostructure, thereby affecting the overall system performance. Therefore, this study establishes a numerical model of composite energy geo-structures considering groundwater seepage and investigates their synergistic heat transfer mechanism of composite energy geo-structures during summer. The results indicate that the heat transfer of composite energy geostructures is 60% higher than that of single energy piles under seepage conditions owing to the synergistic heat transfer of the energy pile and borehole. Groundwater seepage contributes to heat transfer in composite energy geostructures. When the seepage velocity reaches 60 m/a, heat transfer capacity increases by 1.39 compared to non-seepage conditions, while the temperature rise of the structure itself decreases by 25.32%. Under seepage, the upstream energy geostructures exhibit greater heat transfer with the soil than those downstream. The thermal influence area of the energy geostructures significantly reduced upstream and expanded downstream. This study guides the rational application of composite energy geostructures in regions with seepage.关键词：ground-source heat pump;groundwater seepage;energy geo-structure;coupling mechanism;heat transfer performance2|0|0更新时间：2025-08-28
- 摘要：Microchannel heat exchangers, including a bionic secondary branch (MHE-BS), complete vein bionic branch (MHE-CVB), and incomplete vein bionic branch (MHE-IVB), were designed based on the straight secondary branch (MHE-SS) inspired by the leaf vein structure of Parashorea chinensis. ANSYS FLUENT software was utilized to simulate the flow and temperature characteristics of 20 ℃ cooling water entering these heat exchanger structures under a constant heat flux of 50 kW/m2 at different inlet Reynolds numbers (Re=660.07, 990.10 and 1 320.13). The research findings indicate that multistage bionic channel structure can significantly enhance the overall heat transfer performance of the heat exchanger, with MHE-CVB showing more than a 35% reduction in inlet and outlet pressure drop compared to MHE-SS under different working conditions. In addition, it showed an decrease in surface temperature by over 2 ℃ and a strengthening factor for comprehensive heat transfer performance exceeding 1.2.关键词：microchannel heat exchanger;bionic structure;flow and heat transfer;optimal design2|0|0更新时间：2025-08-28
- 摘要：Unnecessary or delayed defrosting results in increased energy consumption, reduced stability, and increased failure rates in refrigeration and heat pump units. Accurately identifying the frost status and timely defrosting are important for improving the performance of refrigeration and heat pumps. Frost status identification methods based on digital and intelligent technologies have shown significant potential. However, existing technologies have significantly reduced accuracy in complex real-world conditions and require urgent improvement. In this paper, we proposed an intelligent recognition method based on the texture features of evaporator surface images. We used a gray-level co-occurrence matrix to extract texture features and combine them with the extreme learning machine optimized by the sparrow algorithm for classification. This is expected to mitigate the impact of external conditions, such as shooting angles and light intensity, thereby achieving strong adaptability. An experimental setup was established to collect 4 125 images of the evaporator in three different frost states under complex working conditions, and the proposed method was validated and compared. The results showed that the accuracy of the method in identifying different conditions can reach 95%, which is significantly higher than that of existing methods by 5-35%. Furthermore, this method has high stability and low cost thereby demonstrating great potential for practical applications.关键词：frosting state recognition;gray level co-occurrence matrix;digital image processing;texture features;defrost2|0|0更新时间：2025-08-28
- 摘要：To address the low thermal storage performance of solid-liquid phase change composites caused by the encapsulation composite effect, composite-shaped phase change materials based on paraffin (PA)/hydrogenated styrene-butadiene block copolymer (SEBS) were prepared using the melt-blending method. A porous mesh structure was designed to optimize the thermal storage performance of the materials through the modulation of process parameters. First, the optimal mass ratio of SEBS-encapsulated PA was determined to be 2∶8; at this ratio, the 80% PA/20% SEBS composite material was well-shaped, and the mass retention rate was maintained above 99%. Furthermore, the results of the orthogonal experiments showed that the process parameters significantly affected the encapsulation and thermal storage properties of the materials, and the extreme difference in the enthalpy of phase change of the nine groups of 80% PA/20% SEBS samples was as high as 28 J/g. Among them, the enthalpy of phase change was increased by 8% when the melting temperature was increased from 150 ℃ to 200 ℃. The results of the orthogonal experiments also showed that the phase change enthalpy of the 80% PA/20% SEBS composites increased by 8%. The optimized PA/SEBS melt blending process parameters were finally determined as: blending time of 2 h, temperature of 200 ℃, stirring rate of 100 r/min, and direct cooling to room temperature. Under this preparation process, the phase transition enthalpy of the composites reached 161.2 J/g with 99.3% crystallinity.关键词：composite shaped phase change materials;porous mesh structure;Thermal storage properties;encapsulation properties;Orthogonal experiments2|0|0更新时间：2025-08-28
- 摘要：With global warming and the rapid growth of the ski industry, the demand for artificial snowmaking technology and improved snow quality has increased, both of which are closely linked to the atomization characteristics of snowmaking nozzles. In this study, the influences of different nozzle interferences and gas-liquid mass mixing ratios (gglr) on the droplet size distribution and collision mechanism in a spray field were investigated. The nozzle spacing (d) represents the degree of interference between the nozzles, whereas gglr signifies the varying degrees of mixing disturbance under identical nozzles. The velocity and size distribution of the droplets in the spray field were measured using a laser particle size measuring instrument and a high-speed camera, whereas the fragmentation and collision of the droplets in the spray field were analyzed based on the Weber number (We). The results indicated that the axial velocity of double nozzles exceeded that of single nozzles at varying spacing intervals. Specifically, when the nozzle spacing was 10 cm and 15 cm, the peak axial velocities were recorded as 5.6 m/s and 5.5 m/s, respectively. The droplet size underwent a non-monotonic variation with the axial distance because of the competition between fragmentation and coalescence, which initially decreased before increasing. The interaction between the spray fields of the two nozzles enhanced the droplet collision, resulting in a higher We number than the individual nozzles. Analysis of the flow field of double nozzles under different arrangement conditions revealed that a higher level of uniformity in particle size distribution was observed when gglr=0.10 and d=15 cm.关键词：artificial snow;velocity distribution;particle-size distribution;nozzle spacing;gas-liquid mass ratio2|0|0更新时间：2025-08-28
- 摘要：Evaporation of functional nanoparticle-containing droplets on solid surfaces plays a key role in applications such as air conditioning, refrigeration, and electronic cooling. In this study, we experimentally investigated the evaporation behavior and particle deposition of nanofluid droplets on solid surfaces. The deposition patterns were photographed, and microscopic characterizations were performed. The results show that the droplets always evaporate in the mode of constant contact radius. Changes in substrate temperature and droplet volume have little influence on the evaporation mode and morphology of the droplets, and the contact angle changes linearly with time. The surfactant can significantly regulate the kinetic behavior of droplet spreading. The addition of only 0.25% of surfactant sodium dodecyl sulfate (SDS) increases the droplet spreading radius from 0.71 mm to 1.12 mm, decreases the initial contact angle from 83° to 54°, and increases the area of spreading by 89%. The substrate temperature and droplet volume significantly affect the deposition patterns after droplet evaporation. The higher the substrate temperature, the larger the droplet volume and the more obvious the coffee-ring pattern formed after evaporation. SDS significantly increases the coffee ring width, which reaches 230 μm when the mass fraction of SDS reaches 1.00%, and the particles have been widely distributed throughout the entire evaporation area, suggesting that the coffee ring effect has been effectively suppressed. By introducing the Ma number, the influence of the Marangoni effect, guided by temperature, volume, and mass fraction changes, on the internal flow of droplets and the mechanism of coffee-ring formation are explained.关键词：nanofluids;droplet evaporation;Particle self-assembly;Coffee ring2|0|0更新时间：2025-08-28
- 摘要：Slurries containing a large number of suspended particles, such as ice slurries, have a strong correlation between internal flow patterns and resistance characteristics. The study of its flow characteristics is of great significance for ensuring safety, energy saving, and the prevention of blockages in slurry transportation systems. To ensure safe and energy-efficient operation of the slurry transport system and prevent blockages, this study experimentally investigated the flow characteristics of slurry in pipelines and its critical Reynolds number (Rec). The focus is on analyzing the flow behavior of the slurry in the transition region, as well as the effects of the ice packing factor (IPF), particle size, and pipe diameter on the slurry flow properties. The results show that the Rec increases with an increase in the IPF, while the Rec decreases with an increase in the pipe diameter and particle size. The flow regime transition of the slurry occurred within the Reynolds number (Re) range of approximately 1 700-2 600. In the transition region, the resistance coefficient of the slurry first increases and then decreases as the Re increases.关键词：ice slurry;solid-liquid two-phase flow;flow characteristics;Critical Reynolds number;resistance coefficient2|0|0更新时间：2025-08-28
- 摘要：Coastal wells are a commonly used intake method for seawater-source heat pump systems because they help mitigate biofouling and increase seawater temperatures. Coastal well water intake systems operate underground across both saturated and unsaturated zones. Therefore, a three-dimensional gas-liquid porous media seepage model of coastal wells was established based on COMSOL Multiphysics to conduct in-depth research on the seepage mechanisms and water intake behavior of coastal wells. The effects of parameters, such as well depth, pressure difference, well arrangement, and well spacing, on the seepage water intake system were studied. The results indicate that as the well spacing increases, the well depth and well flow rate increase, but the flow rate per unit well depth decreases. The flow rate of the coastal wells is directly proportional to the square difference between the coastline and coastal well porosity pressure. When the seawater hydrostatic porosity pressure difference between the coastline and coastal well was 5 m, the influence radius of the well seepage velocity was approximately 25 m. The velocity field was not affected when the distance between the two wells was greater than 50 m, regardless of whether the wells were arranged parallel or perpendicular to the coastline.关键词：seawater-source heat pump;COMSOL;coastal well;gas-liquid;seepage model2|0|0更新时间：2025-08-28
- 摘要：A novel design for intermediate discharge ports (IDPs) is proposed in response to the issues of increased power consumption and reduced efficiency. This approach involved establishing a geometric model of the scroll and IDPs, focusing particularly on the involute curve and employing dynamic mesh techniques for pump-valve joint simulations across various operational scenarios to examine the different types of IDPs. This study explored the influence mechanisms of IDPs on compressor performance, demonstrated the limitations of conventional port-type IDPs in terms of size and efficiency enhancement, and validated the superior exhaust capabilities and efficiency benefits of involute-shaped IDPs. The simulation results confirmed that conventional IDPs were restricted by size limitations and offered only marginal improvements in compressor efficiency. In contrast, the involute-shaped IDP provided enhanced exhaust capabilities, significantly increasing the exhaust flow rate, thus reducing the power consumption and boosting the overall efficiency of the compressor.关键词：scroll compressor;intermediate discharge port (IDP);over-compression;performance optimization under variable operating conditions2|0|0更新时间：2025-08-28
- 摘要：Steam ejectors are vital components of ejector refrigeration systems and have attracted considerable attention owing to their energy savings and environmental protection. In this study, steam ejector models were optimized, validated, and compared by considering the three-dimensional and non-equilibrium condensation effects. The simulation results of the optimization model were compared with those of the ideal gas model. Based on the condensation model, the effects of the turbulence models (Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation methods (LES)) on the simulation results were studied. Complex flow phenomena captured by different models, such as shock waves, non-equilibrium condensation, and boundary layer separation, were compared and analyzed. The results show that the optimized steam ejector model can credibly predict the ejector performance and capture the complex flow phenomena inside the ejector at the lowest computational cost. The maximum liquid mass fraction obtained using the large eddy simulation method is lower than that obtained using the Reynolds-averaged Navier-Stokes method. The maximum relative deviation against experiments of the entrainment ratio was obtained using the large eddy simulation method of 11%. The condensation model reduces the average relative deviations of the entrainment ratio and critical discharge pressure by 72.0% and 29.9%, respectively.关键词：ejector;large eddy simulation;non-equilibrium condensation;shockwave;boundary layer2|0|0更新时间：2025-08-28
- 摘要：Thermal insulation is a crucial performance indicator for cold-chain transportation equipment. Improving the thermal insulation performance can effectively reduce transportation energy consumption and, thus, lower costs. To enhance the thermal insulation performance of refrigerated trucks, this study conducted tests, analyzed the insulation performance using high-reflectivity insulation materials, and analyzed energy consumption. The study obtained data on the heat flux through the box, air cooling rate inside the box, and temperature uniformity. The experiments demonstrated that applying high-reflectivity insulation materials reduced the peak temperature of the external wall surface of the box by 23.6 ℃, leading to less heat transfer into the compartment through the roof. In the absence of refrigeration, the proportion of heat flux reduction was 46.3%, while at the set refrigeration temperature of 5 ℃, the reduction ranged from 16.7% to 26%. The insulation material improved the temperature uniformity of the external wall of the compartment to 1.12 and the internal uniformity to 1.68. This simultaneously allows the refrigeration system to reach the set temperature more quickly and maintain a lower temperature more easily. Compartments with insulation materials reduced the operating frequency of the compressor by 9.1%, leading to energy savings and good energy efficiency. The research results provide new insights into the energy-efficient use of cold chain transportation equipment and are relevant for facilities such as granaries and cold storage facilities with insulation requirements.关键词：refrigerated truck;insulation material;heat leakage;temperature uniformity;energy saving2|0|0更新时间：2025-08-28
- 摘要：In tumor cryoablation therapy, the effective improvement of the cooling rate of the freezing process is a research hotspot. In this study, a novel cryoablation needle with an adjustable throttle nozzle was designed. The external surface temperature of the needle could be reduced to -80 ℃ within just 4 s, while the traditional cryoablation needle with a fixed throttling nozzle requires 73 s. The three-dimensional heat transfer model simulation results show that the temperature around the cryoablation needle drops sharply to -150 ℃ within 120 s, and the fastest instantaneous cooling rate is 1 500-1 575 ℃/min, which achieves the purpose of rapid cooling. In addition, the -20 ℃ isotherm has a small variation range from 60 s to 120 s (increasing from 5 mm to 6.5 mm), and the temperature changes tend to be gentle after 120 s, and the tissue damage range increases to 9 mm, indicating that the tissue damage range increases significantly. Comprehensive studies have shown that the adjustable throttling nozzle cryoablation needle has a higher cooling rate and larger effective ablation range, which is of great significance for clinical cryoablation treatment.关键词：tumor;cryoablation;cooling rate;bio-heat transfer model0|0|0更新时间：2025-08-28
- 摘要：The aim of this study is to optimize the cryopreservation scheme for microcarrier hepatocyte complexes used in artificial liver support systems to improve cell survival and adhesion rates. The effects of cryoprotectant concentration, loading temperature, and method on cell viability were evaluated experimentally. It was found that cell toxicity and osmotic damage were reduced significantly, and higher cell survival and adhesion rates were maintained by using two-step loading of 5% volume fraction dimethyl sulfoxide (Me2SO) at 4 ℃. In addition, we investigated the effects of intracellular ice formation and cooling rate on cell viability and attachment. By performing ice seeding at -6 ℃, the intracellular ice damage was effectively reduced, and the adhesion rate of cells after recovery was improved. The experimental results show that a 10% volume fraction of Me2SO and a cooling rate of 1 ℃/min, despite having high toxicity and osmotic damage, have the best freezing effect due to the smallest difference in thermal expansion. This study provides important techniques for the cryopreservation of microcarrier hepatocyte complexes for artificial liver support systems.关键词：cryopreservation;hepatocyte-microcarrier complex;freeze protectants;thermal expansion damage2|0|0更新时间：2025-08-28
- 摘要：Rainbow trout were used as a research subject to investigate the effects of different preservation techniques on the quality and physicochemical properties of aquatic products during storage. Total volatile basic nitrogen (TVB-N), total viable count (TVC), pH, and drip loss rate were used as technical indicators. A comparative study was conducted on the preservation effects of four preservation methods on rainbow trout flesh, including refrigeration (4 ℃±1 ℃), ice temperature (-1 ℃±1 ℃), high-voltage electrostatic field (HVEF, 3 kV/m) + ice temperature (-1 ℃±1 ℃), and HEVF (3 kV/m) + compound biological preservative (mass fraction: 1.40% chitosan + 0.05% lysozyme + 1.30% theaflavin) + ice temperature (-1 ℃±1 ℃). The results showed that treatment with HVEF + compound biological preservatives effectively inhibited microbial growth. Samples from the refrigeration and ice temperature groups had already decayed by the 10th and 12th day, with TVC reaching 7.12 lg (CFU/g) and 7.13 lg (CFU/g), respectively. In contrast, the TVC values of the HVEF + ice temperature and HVEF + compound biological preservative + ice temperature groups were only 6.32 lg (CFU/g) and 5.89 lg (CFU/g) on the 12th day. On the 14th day of storage, the TVB-N of the HVEF + compound preservative + ice temperature group was only 20.17 mg/100 g, which was much lower than that of the other three groups. This investigation indicates that compared to refrigeration and ice-temperature storage, treatment with HVEF + composite preservatives can effectively delay the spoilage process of fish and extend the shelf life of rainbow trout by four days.关键词：high voltage electrostatic field;biological preservatives;freezing and refrigeration;rainbow trout;quality0|0|0更新时间：2025-08-28
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