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.

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.

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.

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.

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.

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.

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.

Heat pump technology has become an essential solution in the field of medium- and low-temperature heating due to its superior efficiency in converting electrical energy into thermal energy. However, owing to the lack of stable heat sources during winter in northern China, it is necessary to store the heat sources within the urban area throughout the seasons to ensure the stability of the heat provided by the heat pump system. In this study, based on the project of seasonal/daily thermal storage of river water in Guantao, a simulation model was constructed using the Transient System Simulation Tool (TRNSYS). A sensitivity analysis of the thermal energy storage unit parameters was conducted under the constraint of the fixed site area. The configurations and strategies of the daily thermal energy storage were optimized. The results show that the temperature rise of the thermal energy storage unit reaches 3.2 ℃ after 10 years of operation, effectively preventing the soil heat imbalance. The distance between the buried pipes and the depth had the greatest influence on the performance of the system. The total length of the pipes could be reduced by approximately 23% with a spacing of 4 m and a depth of 150 m. The daily thermal energy storage system should be matched to the valley power storage heat and heat release load to avoid wasting the valley power. If the storage heat power is large, the volume of the storage tank can be increased, and the flat power heat release is considered. The optimized system improves the utilization rate of valley power and reduces annual operating costs by 11.2%.

Energy storage technology can balance the mismatch between energy supply and demand, which is an important link between the use of renewable energy and waste heat. Absorption thermal energy storage has attracted considerable attention in recent years owing to its high energy-storage density, high energy-storage efficiency, low charging temperature, low heat loss, and flexible output. A state-of-the-art review of advanced cycles, working pairs, and experimental prototypes was conducted. The development of advanced cycles has further improved the energy storage density and efficiency and lowered the charging temperature. The screening of novel working pairs solved the crystallization problem of conventional salt solutions, increased the options of working fluids for different scenarios, and reduced costs. The successful development and operation of experimental prototypes have confirmed the excellent performance of absorption thermal energy storage and paved the way for its promotion and application. In conclusion, the challenges and opportunities of absorption thermal energy storage for the future are summarized, and the development direction is discussed.

Topological fins can significantly improve heat transfer in latent heat storage units. In this study, a two-dimensional topology optimization model for a shell-and-tube latent heat storage unit was developed and experimentally validated. The optimal fin for different operating conditions and charge-discharge cycles was investigated. Box-counting dimensions and fin surface areas per unit length were used to characterize the topological fins. The results showed that increasing the charging time simplified the fin structures, whereas discharging times of more than 600 s extended the fin tips. For the 3 000 s charge-discharge cycle, the optimal fin increased the surface area per unit length by 80% and the discharge energy density by 37.6% compared to the fin for the 3 000 s charging process. The topological fin for a 300 s discharge-charge cycle with an extended branch resulted in a 7.7% increase in heat storage density.