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.

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.

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.

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.

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.

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.

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.

As the driving component of a valved linear compressor, the matching relationship between the motor force and gas force directly affects the performance of the compressor. A simulation model of the linear motor was established based on the equivalent gas-force model. In addition, a test bench for the valved linear compressor was constructed to analyze both the simulation and experimental results under various working conditions. This study aimed to investigate the performance of a compressor across different operating scenarios while verifying the reliability of gas force linearization. When the inflation pressure and piston pressure were 0.2 MPa and 5 mm, respectively, the resonance frequency of the experiment and simulation was 50 Hz, and the motor efficiency was 84.3%. The maximum relative errors of the input work, voltage, current, and motor efficiency were 25.8%, 21.7%, 22.7%, and 13.5%, respectively. This indicates that the motor efficiency of the compressor is related to its resonance frequency and that the motor efficiency of the compressor is the highest when the resonance frequency is consistent with the operating frequency. The simulation model of the linear motor is reliable, and the calculation results for the gas load are relatively accurate.

In this study, a phase-change heat-storage water tank with a flat-plate storage plate was designed with phase-change materials. A heat-storage water tank model was constructed using the same staggered arrangement. Experiments and simulations were used to investigate the heat storage and discharge performances of a flat-plate-filled phase-change heat-storage water tank and the influence of the discharge flow rate on the heat release performance of the change materials. The role of different discharge flow rates in improving the heat release performance of phase change materials is discussed. The results show that filling a 98 L water tank with 12.15 L of phase change materials in a flat plate manner increased the heat storage capacity of the water tank by 17.91% while improving the stability of the system operation. By analyzing the flow rates under different heat release modes, it was found that at a discharge flow rate of 100-175 L/h, the heat release ratio of the phase change materials was maintained above 88%. The hot water supply volume reached 135 L. However, the heat transfer between the fluid and the phase change materials was no longer timely when the flow rate increased. The heat release ratio of the phase change materials gradually decreased to 81.5%, and the hot-water supply volume decreased to 125 L. To improve the heat discharge performance of phase change materials in a heat-storage water tank, it is necessary to ensure sufficient external heat transfer conditions and fundamentally improve the heat exchange capacity of the phase change materials.

Ovarian tissue cryopreservation is an important method for female fertility preservation. Slow freezing of ovarian tissue results in poor follicular survival and low retransplantation efficiency. This study optimized the ovarian tissue cooling procedure by ice seeding, and the effects of ice seeding temperature and cooling rate after seeding on ovarian tissue cryopreservation were analyzed. The programmed cooling apparatus was combined with an ultrasonic device to achieve the ultrasonic seeding of ice crystals, and the ultrasonic intensity was screened. The ovarian survival and histology were assessed after rewarming. The results revealed that the optimized cooling procedure with ice seeding reduced the damage to ovarian tissues. When ice seeding was triggered at -11 ℃ with a cooling rate of 1 ℃/min after nucleation, follicle survival was 88.02%. Ultrasonic nucleation equipment enabled contactless ice seeding of the samples, reducing the risk of contamination and improving the success rate of ice seeding. Furthermore, the follicle survival rate of frozen ovarian tissue increased to 88.38%. The optimization of the procedure and the improvement of the equipment improved the effect of ovarian tissue cryopreservation, reduced the risk of introducing contamination during the cryopreservation process, and provided a new method for the slow cryopreservation of ovarian tissues in clinics.