Wenzhi Cui

To address the high heat flux of compact deuterium–deuterium neutron-generator targets, steady-state thermal–fluid–structural coupled simulations were performed for a water-cooled Ti target. The effects of coolant mass flow rate, channel depth, Ti film thickness, and Cu cover thickness on temperature, pressure drop, and structural stress were investigated. Under baseline conditions, the maximum Ti temperature remained below 200 °C, with a pressure drop of 1.58 MPa and maximum equivalent stresses of 88.9 MPa in Ti and 78.5 MPa in Cu. Increasing mass flow rate reduced the target temperature but provided diminishing thermal benefits while significantly increasing pressure drop. Increasing channel depth reduced pressure drop but increased target temperature. Ti film thickness mainly affected the thermal resistance of the Ti layer, whereas Cu cover thickness influenced both thermal and structural responses. Coupling between mass flow rate and channel depth led to trade-offs among temperature, pressure drop, and stress, while competing thermal and pressure loads produced a non-monotonic stress response. These results provide guidance for cooling design and operating parameter selection for D-D neutron targets.

Thermal interface materials are critical components for ensuring efficient heat dissipation in thermal management systems. The current research focus is to fabricate thermal interface materials (TIMs) that demonstrate high thermal conductivity while at low filler loadings. In this study, an aligned, thermally conductive skeleton was fabricated via the freeze casting method, utilizing carbon nanofibers (CNFs) and nickel (Ni) particles. This skeleton was subsequently infiltrated with silicone rubber (SR) to obtain the polymer composite. Within the aligned skeleton, CNFs and Ni particles are densely packed, with the Ni particles acting as conductive bridges between adjacent CNFs. This bridging effect facilitates a substantial enhancement in the overall thermal conductivity with only a minimal addition of Ni. By combining the skeleton’s microstructure with thermal performance, the effects of key parameters on thermal conductivity were systematically investigated. A maximum thermal conductivity improvement of 64.8% was achieved by hybridizing CNFs with a small amount of Ni (1.09 vol%) compared to the CNF-only counterpart. Furthermore, at a low total loading (8.02 vol% CNFs and 1.09 vol% Ni), the composite achieved a thermal conductivity of 3.30 W/(m·K). This value was 47.2% higher than that of a CNF-only TIM and 36.2% higher than that of a composite prepared by common freezing under the same filler composition. Additionally, the incorporation of Ni enhanced the composite’s thermal stability. Moreover, the composite exhibited a favorable combination of enhanced mechanical strength and excellent elasticity.

Mechanical ventilation achieved by range hoods and make-up air systems has been proven effective in enhancing pollutant capture efficiency, suppressing the diffusion of indoor pollutants, and thereby improving indoor air quality in residential kitchens. However, the impacts of specific make-up air strategies, particularly the air-supply distance and air-jet angle, on airflow organization and pollutant control performance remains insufficiently explored. In this study, an organized make-up air system with ceiling-mounted supply openings was investigated using computational fluid dynamics to evaluate both overall and local pollutant control effectiveness under varying air-supply distances and air-jet angles. The results indicate that, compared with the conventional window-based natural make-up air mode (i.e., relying solely on opening windows for air supplementation), the proposed system reduces indoor PM2.5 concentrations by more than 44%. Using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method, the optimal air-supply distance and air-jet angle were identified as 1.6 m and 60.9°, respectively, based on the layout of the studied kitchen. Under this optimal configuration, the individual intake fraction decreased by 62%, and the capture efficiency of the range hood exceeded 90%. In addition, the pollutant control performance of the make-up air system was found to be significantly influenced by kitchen layout and obstruction from furniture walls.

This study aims to experimentally evaluate a personal comfort system based on a radiant panel (R-PCS) that can regulate the thermal environment of the sleep zone during summer, with a focus on improving both the thermal comfort and energy efficiency of this system. To investigate thermal comfort under the coupling effect of different covering conditions and operating parameters of the R-PCS, the changing pattern of thermal environment parameters in the berth area and human skin temperature are analyzed. Then, the Predicted Mean Vote (PMV) -Predicted Percent Dissatisfied (PPD) index is employed for assessing the thermal comfort of the human body and energy-saving efficiency of the system. The results show that this system can satisfy the thermal comfort requirements of the human body in the berth area. Meanwhile, the corresponding cooling energy consumption of the R-PCS is significantly lower than that of the traditional HVAC system, indicating that the developed system has significant energy-saving potential in building design.

Heat transfer enhancement is always pursued in the industry to achieve high-performance and low-energy-consumption heat exchange devices and systems. For decades, various types of heat transfer-enhancing tubes with differing geometries and wall configurations have been developed. In this paper, the heat transfer and pressure drop characteristics of air inside an innovative heat transfer tube with regular wall dimples, namely a vortex-enhanced tube, which has a great application prospect in the gas–gas heat exchanger, are numerically studied with an experimentally validated model. The effects of the depth, axial pitch, and radial rotation angle of the dimple in the tube wall on the convective heat transfer coefficient and friction drag coefficient are comprehensively analyzed. Based on the Performance Evaluation Criteria (PEC) of the tubes, the optimal parameters of the vortex-enhanced tube are obtained. When Re ranges from 10,000 to 40,000, the comprehensive evaluation factor of the vortex-enhanced tube is 1.29 times higher than the smooth tube. Dimple pacing, dimple depth, and dimple helical angle of the optimal tube type are 8 mm, 6 mm, and 83°, respectively.