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.

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.

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.

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.

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.

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.

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.

With the development of cold chain Internet of Things (IoT) technology, real-time temperature monitoring and data sharing have become important means to improve the efficiency of chilled meat supply chain management. In this paper, a strategy for optimizing time and temperature coordination based on the cold chain IoT was proposed to improve the operational efficiency of the chilled meat supply chain. Based on predictive microbiology and system reliability theory, this study investigated the effects of time and temperature on the quality of chilled meat. A quality-change model for chilled meat and an energy consumption model for the chilled meat supply chain were developed. To illustrate this approach, a case study of a chilled chicken supply chain was conducted. The findings revealed that there is an optimal level of freshness in the chilled meat supply chain that maximizes the benefits of the supply chain. If the freshness level in one stage deviates from this optimal value, subsequent stages can adjust the time and temperature to achieve maximum supply chain efficiency.

In this study, the critical snow formation height of a mixed single-aperture nucleator in an artificial snow machine was examined. The threshold values of critical snow formation height were experimentally measured at different air-water pressure ratios and ambient temperatures, and the effects of air-water pressure ratios and ambient temperatures on the threshold values of critical snow formation heights were analyzed. The results showed that the threshold value for the critical height of critical snow formation did not exist at temperatures of -5 ℃ and -10 ℃ under the working conditions with a gas-water pressure ratio of 0.40 MPa∶0.40 MPa, but snow formation could be realized at -15 ℃, and the threshold value for the critical height of critical snow formation was 50-55 cm. When the gas-water pressure ratio is 0.50 MPa∶0.45 MPa or 0.50 MPa∶0.40 MPa, snow can be formed at ambient temperatures of -5 ℃, -10 ℃, and -15 ℃. The gas-water pressure ratio and ambient temperatures have a certain influence on the height of critical snow formation. Under the same ambient temperature, the greater the gas-water pressure ratio, the lower the critical snow height. Provided that the gas-water pressure ratio remains constant, the critical snow height decreases when the ambient temperature lowers from -5 ℃ to -15 ℃, and the trend of the change is more obvious in the temperature interval from -5 ℃ to -10 ℃.

Nucleator nozzles play an important role in promoting the rapid nucleation, crystallization, and snow formation of artificial snow droplets. A visual experimental platform was designed to investigate the gas-liquid two-phase flow process inside the nucleator nozzle and its influence on atomization behavior. The results showed the presence of a two-phase annular flow within the nucleator nozzle and a continuous hollow-cone spray field outside the nucleator nozzle. As the gas-liquid pressure ratio (Φ_GL) increases, the interfacial disturbance waves at the gas-liquid interface of the internal flow gradually disappear. As the air core occupied more space, the liquid film thickness gradually decreased and became uniform and stable. This markedly improved the atomization efficiency and quality. When the Φ_GL was increased from 20% to 67%, the uniformity and stability of droplet distribution increased by 17% and 60%, respectively. This research offers important guidance for the structural design of high-performance atomized components.