The jet/bifurcated expanding microchannel heat sink (jet diameter: 200 mu m, channel number: 48, channel width: 53.5-255.7 mu m, channel depth: 200 mu m) is designed for ultra-high heat flux embedded cooling. Specifically, three types of heat sinks with various bifurcated locations are fabricated on silicon base: jet/downstream-bifurcated expanding microchannel (JDEM), jet/midstream-bifurcated expanding microchannel (JMEM), and jet/ upstream-bifurcated expanding microchannel (JUEM). After the validation of experimental setup, deionized water flow boiling experiments are conducted on JDEM, JMEM and JUEM spanning a heat flux range of 125-1180 W/cm2 under various jet velocity (Vj: 1.5 m/s, 2 m/s, 2.5 m/s) and inlet subcooling (DTsub: 20 degrees C, 50 degrees C, 70 degrees C) conditions. The boiling heat transfer characteristics, pressure drop characteristics and thermalhydraulic performance are then comprehensively compared. The results show that, compared with JMEM and JDEM: 1) JUEM with upstream-bifurcated location pre-triggers the onset of nucleate boiling (ONB) owing to its elevated nucleation sites, resulting in a decreased wall superheat at ONB of 0.6-3.7 degrees C; 2) JUEM achieves a higher critical heat flux (CHF) due to its suppression of backflow. Particularly, the maximum CHF of JUEM reaches 1180 W/cm2 at a low pressure drop of 42.5 kPa under Vj = 2.5 m/s and DTsub = 70 degrees C, outperforming other two-phase jet/microchannel heat sinks reported in the literature; 3) JUEM exhibits higher heat transfer coefficient (HTC) and lower thermal resistance owing to its elevated nucleation sites and suppression of backflow; 4) JUEM has superior thermal-hydraulic performance as the increase in HTC outweighs the increase in pressure drop. This work provides an ultra-high heat flux embedded cooling scheme by integrating jet/bifurcated expanding microchannels into a silicon chip.

In this work, two pseudopotential lattice Boltzmann models with high-order isotropic interaction forces (6th-and 8th-order isotropic models) are proposed for simulating multiphase flows. Unlike the conventional pseudopotential model with low-order isotropic interaction forces (4th-order isotropic model), which incorporates only nearest-neighbor interactions when computing interaction forces, the pseudopotential models with high-order isotropic interaction forces incorporate both nearest-neighbor interactions and next-nearest-neighbor interactions, thereby effectively reducing the anisotropic contributions in the high-order error terms of interaction forces. In addition, for the proposed models, discrete additional terms are introduced into the collision step, enabling the density ratio and surface tension to be independently adjusted. The performance of the proposed models is validated by six benchmark cases. First, numerical simulations of the planar interface demonstrate that the proposed models can achieve better thermodynamic consistency. Subsequently, the proposed models are used to simulate the static droplet and the results show that they can significantly suppress spurious currents while also allowing the surface tension to be adjusted independently of the density ratio. Moreover, the additional computational cost of the proposed models is nearly negligible compared with the model with low-order isotropic interaction forces. Then, the proposed models are adopted to simulate the moving droplet and the results indicate that they can achieve better Galilean invariance. Finally, three complex dynamic cases, including elliptical droplet oscillation, bubble merging, and droplet impact on a thin liquid film, are simulated by the 8th-order isotropic model, demonstrating that the proposed model can accurately simulate multiphase flows with large density ratios.

Expanding microchannels have the potential to achieve high-efficiency heat removal with reduced pumping power for practical applications. In this study, a two-dimensional hybrid phase change lattice Boltzmann (LB) model featuring an adjustable latent heat is employed to systematically investigate the effects of expanding ratio (ER), Reynolds number (Re), and Jakob number (Ja) on bubble dynamic behaviors, heat transfer performance, and pressure drop in expanding microchannels under negligible gravity conditions. Simulation results show that periodic bubble dynamic behaviors govern flow pattern transitions, affecting local heat transfer characteristics and consequently overall heat transfer performance in expanding microchannels. The spatial derivative of thermal-convection resistance (drf,x/dx) is found to accurately identify flow pattern distribution along the microchannel. Compared with straight microchannel (SM), expanding microchannel (EM) with ER = 7/150 achieves an improvement of 55.0% in comprehensive thermal-hydraulic performance due to enhanced thin liquid evaporation in slug flow and decreased pressure drop. Moreover, increasing Re nonlinearly modulates the dominance of liquid film evaporation, resulting in a 161.6% improvement in overall heat transfer performance under the condition that the liquid film reaches its minimum thickness at the onset of dryout, compared with the case without liquid film evaporation. Before the occurrence of persistent partial dryout, increasing Ja enlarges the liquid film area and intensifies evaporation, which improves heat transfer while increasing pressure drop. Finally, dimensionless correlations of heat transfer and pressure drop for EM are proposed. These twodimensional results provide qualitative insights, while the reported quantitative enhancements are not directly transferable to three-dimensional devices.

Fluid flow and phase-change processes under variable-gravity are of significant scientific interest in space science, thermal control engineering and planetary exploration. However, current variable and micro-gravity experiments mainly rely on space stations or parabolic flights, which are limited by short experimental durations, high costs, and restricted repeatability. To overcome these limitations, this study develops a ground-based experimental approach on diamagnetic levitation. Deionized water is adopted as the working fluid in a strong magnetic field to conduct representative variable-gravity experiments, including single-droplet levitation, liquid bridge formation, capillary flow, and boiling. The experimental results show that: in the single-droplet levitation experiment, stable levitation can be achieved when the central magnetic field reached 23.28 T. In the capillary rise experiment under typical gravity conditions, the maximum deviation between the measured liquid height and the theoretical prediction is 5.25

Phase-change transpiration cooling is an efficient thermal control solution for aerospace vehicles under hypersonic conditions. To predict its performance, a simplified equivalent numerical model is proposed for the liquidgas phase change process in porous media, which innovatively introduces the Lee model and couples the twophase mixture model, Darcy's equation, and local thermal non-equilibrium model. Additionally, by proposing a coupling method that simplifies the influence of the mainstream region on the phase-change transpiration cooling process within the porous region to pressure and heat flux boundary conditions applied at the interface, this approach avoids the requirement for multiple iterations while preserving computational accuracy, thus effectively reducing the complexity of the coupled solution. Using the improved numerical strategy, transient simulations of wedge-shaped porous cones under hypersonic conditions (Mach 6.5, altitude 30 km) have shown that: increasing the leading-edge radius or decreasing the half-apex angle reduces stagnation heat load but affects aerodynamic performance and structural reliability; regional graded porosity (especially circumferential gradient along the leading edge) lowers stagnation temperature by 41 K; regional control of coolant supply mitigates heat transfer deterioration, reducing the maximum temperature by over 350 K.

To achieve chip-level jet microchannel cooling with a high heat flux, the silicon-based jet/straight microchannel and jet/pin-fin microchannels have been successfully fabricated and investigated using zeotropic emulsions. The boiling heat transfer performance of HFE-7100/water zeotropic emulsions in these jet microchannels is experimentally studied and compared with deionized water, HFE-7100, and sodium dodecyl sulfate (SDS) aqueous solution. The effects of surfactant SDS and discrete phase concentration (0 similar to 3 wt%) on boiling heat transfer are also studied. The results show that the liquid density and dynamic viscosity of zeotropic emulsions are higher than those of deionized water, while the thermal conductivity, specific heat capacity, surface tension, and contact angle are lower than those of deionized water. The addition of surfactant SDS can improve the stability of zeotropic emulsions. The boiling heat transfer of zeotropic emulsions is enhanced due to the heat absorption of boiling and the base liquid disturbance caused by the volume expansion of the discrete phase droplets. Zeotropic emulsions can significantly expand the high-efficiency boiling phase change range, and increase the boiling utilization efficiency (BUE, defined as the ratio of two-phase heat flux to total heat flux). Moreover, zeotropic emulsions (especially with SDS) can decrease wall superheat at the onset of nucleate boiling of the base liquid and suppress the boiling hysteresis because the decrease in surface tension is beneficial to activate more nucleation sites. However, when heat flux approaches critical heat flux, the competitive mechanism of phase change between the base liquid and the discrete phase leads to heat transfer deterioration. The severity of this deterioration intensifies with increasing discrete phase concentration. This work bridges lab-scale research to industrial needs for chip-level thermal management.

To enhance boiling heat transfer for ultra-high heat flux dissipation in chips, silicon-based heat sinks with hybrid jet/gradient-density-pin-fin-microchannel are proposed. Specifically, hybrid jet/uniform-pin-fin-microchannel (JUPM, serving as a control case without gradient density design), hybrid jet/dense-to-sparse-pin-finmicrochannel (JDPM), and hybrid jet/sparse-to-dense-pin-fin-microchannel (JSPM) are fabricated. By combining a data acquisition system with a high-speed microscope camera, the heat transfer performance, boiling flow patterns, pressure drop and coefficient of performance (COP) of deionized water in JUPM, JDPM, JSPM across a range of jet velocities (Vj = 1.5, 2, 2.5 m/s) and inlet subcoolings (Delta Tsub = 30, 50, 70 degrees C) are experimentally investigated. The results are further benchmarked against those from the heat sink with hybrid jet/continuous-microchannel (JCM), revealing that: 1) JSPM, JDPM and JUPM all improve the critical heat flux (CHF) due to the enhanced liquid supply to the heating surface (caused by the suppressed reverse flow and capillary-driven liquid bridges). Moreover, JSPM further increases the CHF compared to JDPM and JUPM due to the presence of more liquid bridges downstream. Particularly, JSPM achieves the highest CHF of 1464 W/cm2 when Vj = 2.5 m/s and Delta Tsub = 70 degrees C; 2) JSPM, JDPM and JUPM all increase the HTC due to more nucleation sites in the early boiling stage, the highly-efficient thin film evaporation in the middle boiling stage, and the enhanced liquid supply to the heating surface in the late boiling stage. Moreover, JSPM has a higher HTC than JDPM and JUPM due to the further enhanced liquid supply; 3) JUPM, JDPM and JSPM all reduce the pressure drop due to the suppression of reverse flow and violent vapor generation from local dry out. Although they have comparable pressure drop, JSPM yields a slightly lower value in the late boiling stage; 4) JSPM, JUPM and JDPM all have better thermal-hydraulic performance (i.e., higher COP). Moreover, JSPM achieves superior performance compared to JUPM and JDPM, with a maximum COP of 13197 when Vj = 1.5 m/s and Delta Tsub = 70 degrees C.

The capillary force plays a crucial role in phase-change transpiration cooling within the porous media; however, its role at the pore scale is still less studied. In this study, the capillary-driven phase-change transpiration cooling in heterogeneous porous media is initially investigated at the pore scale using a pseudo-potential phase-change lattice Boltzmann method with a modified wetting boundary scheme. The influences of heat flux, surface wettability, and porosity on the liquid fraction, coolant mass flow rate, and dimensionless temperature rise are analyzed. In terms of the dynamic characteristics of phase-change transpiration cooling, the porous layer reaches thermal equilibrium through the combined effect of the evaporation and the capillary-driven self-replenishment of the coolant. For the heat flux, the coolant mass flow rate increases as the heat flux increases below a critical value. Once the heat flux exceeds this critical value, the capillary-driven pumping capability is suppressed, leading to a reduced mass flow rate and a significant decrease in the liquid fraction. For the surface wettability, hydrophilic surfaces increase the coolant mass flow rate, resulting in a higher liquid fraction and a lower temperature rise compared to less wetting surfaces. For the porosity, the lowest equilibrium surface temperature rise is achieved at epsilon = 0.5, while deviations from this value lead to higher surface temperature rises. At higher porosities, the surface temperature rise increases gradually and rises sharply at epsilon = 0.8. These findings provide mechanistic insight into the pore-scale capillary effects within the phase-change transpiration cooling systems.

This paper numerically investigates the drag coefficients (CD) and Nusselt numbers (Nu) of gas slip flow around unconfined and semi-confined spheres using second-order velocity slip (with nonplanar modification) and temperature jump boundaries and variable gas properties. The effects of Knudsen number (Kn), Reynolds number (Re), gap ratio (dgap/dsp), and temperature ratio (Tsp/T infinity) are comprehensively analyzed. It is obtained that: (1) for the unconfined sphere, CD decreases as Kn and Re increase due to the enhanced velocity slip and weakened viscous effect; for the semi-confined sphere, CD decreases at lower Kn and Re but increases at higher Kn and Re root due to the enhanced compressibility effect (Ma = 2/pi gamma KnRe); for both spheres, Nu decreases as Kn increases due to the dominant temperature jump, but increases as Re increases due to enhanced convection; for the semi-confined sphere, the enhanced compressibility effect changes the dominance from temperature jump to velocity slip. (2) CD firstly rises and then declines with narrowing dgap/dsp due to the variation of velocity gradient when the sphere moves from outside to inside and last bottom of wall boundary layer; besides, with narrowing dgap/dsp, the confinement effect weakens the rarefaction effect but enhances the compressibility effect on CD; Nu firstly rises and then declines and last rises with narrowing dgap/dsp due to the corresponding variation in temperature gradient; furthermore, the confinement effect shifts dominance from temperature jump to velocity slip and finally back to temperature jump with narrowing dgap/dsp; (3) for both spheres, CD and Nu increase with increasing Tsp/T infinity due to the rise in the gas viscosity, and gas temperature gradient and thermal conductivity, respectively. Consequently, CD and Nu correlations of unconfined and semi-confined spheres are proposed considering effects of convection, rarefaction, compressibility, confinement, and temperature.

The silicon-based hybrid distributed jet-expanding microchannel heat sinks (JEMs) with different branching numbers (JEM#1 with single branching number, JEM#2 with double branching number, JEM#3 with triple branching number) are proposed for high-heat-flux chip-level cooling. The flow boiling curves (including CHF correlation), bubble dynamic behaviors and temperature/pressure oscillations, heat transfer coefficients, effective thermal resistances and pressure drops of deionized water in JEMs with different branching numbers under different jet velocities (V-j = 1.5 similar to 2.5 m/s) and inlet subcoolings (Delta T-sub = 30 similar to 70 degrees C) are examined and compared with those of distributed jet-flat surface heat sink (JFS). It is found that: 1) at the onset of nucleate boiling (ONB), due to the increased nucleation sites, the wall superheat decreases with increasing branching number (JEM#3 < JEM#2 < JEM#1 < JFS), and the explosive boiling and boiling hysteresis in JFS are suppressed in JEMs; 2) during the early boiling stage after ONB, the heat transfer performance and pressure drop increase with increasing branching number (JEM#3 > JEM#2 > JEM#1 > JFS) due to the increased nucleation sites and narrowed microchannels, respectively; 3) during the later boiling stage after ONB, JEM#1 with excessively expanding microchannels and JEM#3 with narrowed microchannels are more prone to cause bubble clogging and reverse flow than JEM#2, resulting in heat transfer deterioration and pressure drop increment and thus reordering the heat transfer performance (JEM#2 > JEM#3 > JEM#1 > JFS) and pressure drop (JEM#3 > JEM#1 > JEM#2 > JFS); 4) Due to the more stable flow boiling, JEM#2 achieves the highest critical heat flux (CHF) of 1100 W/cm(2) at a small pressure drop of 37.4 kPa, the highest heat transfer coefficient (HTC) of 126.0 kW/(m(2)K), the lowest thermal resistance of 0.100 Kcm(2)/W, the smallest temperature oscillation of 3.7 degrees C and pressure oscillation of 1.4 kPa.

In order to achieve high-efficiency heat dissipation of a “stacked” time–frequency payload and high-precision high-stability temperature control of the payload upper module under complex space thermal environment, a two-stage thermal control system is proposed and established. In the first stage, the controllable heat dissipation path based on semiconductor thermoelectric coolers (TEC) along with microchannel vapor chamber (VC) is employed to build and control the thermal resistance between the upper module and the cold plate. In the second stage, the thin-film electric heater is used to carry out short-period PWM temperature control for the internal electronic components. The two-stage thermal control strategy realizes efficient heat dissipation of the upper module and ensures temperature stability of the internal point. To satisfy the high-precision and high-stability requirements, the thermal control system also features with on-orbit calibration and debugging capabilities, further improving the robustness of the system. In addition, this paper also analyzes the difference between ground test and on-orbit flight environment of key components of the system. Performance optimization is carried out according to on-orbit environment. Results show that the thermal control design is feasible, and the optimization methods for the difference of on-orbit environment are effective. Using the two-stage precision temperature control, the temperature fluctuation of all high-precision constraint points of the payload upper module precedes the requirements of ±0.1 ℃.

A numerical simulation with second-order velocity slip and temperature jump models has been conducted to investigate gas slip flow and heat transfer over a semi-confined cylinder in proximity to a solid wall. The effects of rarefaction (characterized by Kn), convection (characterized by Re), compressibility (characterized by Ma), confinement (characterized by gap ratio dgap/dc), and temperature (characterized by cylinder-gas temperature ratio Tc/T infinity) on the drag coefficient (CD) and Nusselt number (Nu) of a semi-confined cylinder have been comprehensively analyzed. It is found that: (1) with increasing Ma, the dominant effect determining the variation of CD with Kn changes from rarefaction effect to compressibility effect, while the dominant effect determining the variation of Nu with Kn changes from temperature jump to velocity slip; (2) with increasing Ma, the variation of CD with increasing Re changes from a monotonic decrease to a non-monotonic variation owing to the compressibility effect, while Nu increases monotonically with increasing Re owing to an enhanced convection effect; (3) with decreasing dgap/dc, CD first increases, then decreases owing to the variation of gas velocity gradient and pressure surrounding the cylinder, while Nu first increases, then decreases, finally increases again owing to the variation of gas velocity and temperature gradient surrounding the cylinder; (4) with increasing Tc/ T infinity, CD and Nu increase owing to increases of gas dynamic viscosity and pressure, thermal conductivity and temperature gradient, respectively. Finally, dimensionless correlations for CD and Nu of a semi-confined cylinder with comprehensive considerations of rarefaction, convection, compressibility, confinement, and temperature effects are proposed.

Evaporation, condensation and fluid flow within an S2-shaped axial groove heat pipe (S2-AGHP) are numerically simulated using the Volume of Fluid (VOF) method. The flow and thermal characteristics of the S2-AGHP (with aluminum pipe shell and ammonia as working fluid) under various axial gravity coefficients (0, 0.1, 1.63, 3.72, 9.8, and 19.6 m/s2) are compared. It is revealed that the presence of axial gravity acting from the condenser region to the evaporator region substantially alters the vapor-liquid interface, accelerates the reflux of condensed ammonia, and therefore improves the thermal performance of the S2-AGHP by approximately 40 %. Even a relatively low axial gravity coefficient (0.1 m/s2) can substantially boost the thermal performance of the S2-AGHP. However, raising the gravity coefficient beyond a threshold (1.63 m/s2) does not yield additional performance improvements of the heat pipe. The results can help better understand the flow dynamics and transport mechanisms within an S2-AGHP, offering certain engineering guidance for the design of S2-AGHPs applied in aerospace and deep space exploration.

The development of flexible electronics needs efficient cooling devices. The porous wick, the key component in a heat pipe (HP) and vapor chamber (VC), is generally fabricated by sintering copper particles at high temperatures (>1000 °C), which makes it only formed on an inflexible substrate. In this work, one three-tier hierarchical porous structure (mesocrack, micropore, and nanopapillae) was fabricated via a low-temperature sintering method based on the utilization of self-reducing metal precursors (∼300 °C), which can be used as a flexible porous wick. The mesocrack, acting as the main water flow channel, efficiently decreases the flow resistance. The micropore, covered with densely distributed spore-like nanopapillae, creates a heterogeneous wetting surface. By harnessing the synergistic effect of hydrophobic drag reduction and hydrophilic driving force enhancement, the capillary performance is significantly improved. The obtained wick on the flexible substrate can overcome the dilemma between diminishing viscous resistance and strengthening capillary force at different length scales. It can achieve an ultimate wicking coefficient of 7.132 mm/s0.5, representing an enhancement of 9.1% compared to the best micro/nano wick structure in the previous works. Moreover, for the flexible light-emitting diode, the passive cooling approach utilizing the fluid transport and evaporation within the porous structure fabricated in this study, in comparison to the natural cooling, achieved a temperature decrease of 35.9 °C, resulting in a cooling effect of up to 35.1%. The proposed method resolves the challenge of fabricating a porous wick for flexible HP and VC, and it will open up a way for the cooling technique of flexible electronics.

The water in confined space is still one unclear issue due to the limitations of experimental technique. In this work, the metadynamics (MetaD) simulation method was used to systematically investigate the water behavior confined in hydrophobic nanochannel (carbon nanotube, CNT and carbon nanocone, CNC). We find the phase transition of water is more susceptible to occurring in carbon channel compared to that between graphene plates. The water under hydrophobic nanoconfinement becomes metastable due to the competition between bulk and surface energy, which will lead to a cavitation as the channel size continues decreasing. It shows there exits one critical diameter, under which the water prefers to spontaneously cavitate in CNT. As the apex angle of CNC increases, its tendency varies from being wet to being dry caused by the different dewetting free energy cost. Due to the influence of water thermal motion, as the CNT operating temperature increase, CNT is more inclined to be wet accordingly. The findings in this work can contribute to the understanding of metastable water behavior in hydrophobic nanochannel and the design of innovative CNT/CNC device.

Accurate prediction of building thermal load and indoor temperature serves as a critical prerequisite for energy-efficient and comfortable HVAC system operation. Prediction via RC thermal network model represents a key methodology, with thermal parameter identification being the cornerstone of this approach. Conventional intelligent search methods suffer from prohibitive computational demands, hindering their practical engineering applications. Furthermore, the noise introduced by flawed sensor and transmission interference significantly compromises the reliability of the model-based prediction method. This study proposes an online identification method integrating Polynomial Kalman Smoother (PKS) and Recursive Generalized Total Least Squares (RGTLS) to achieve robust thermal parameter identification in noisy conditions and enable real-time thermal load and indoor temperature predictions. PKS first estimates noise error covariance matrix, followed by RGTLS's parameter identification. Experimental validation demonstrates that the method accomplishes high-resolution parameter identification within 2 s while eliminating extensive historical data storage requirements, substantially reducing hardware configuration demands. In noisy conditions, the average identification error of the parameters decreased from 59.78% to 6.35%, achieving the MAE of 0.48. C for indoor temperature and 6.90 kW for cooling power prediction. Noise tests and hyperparameter sensitivity analyses reveal that the method achieves high performance and robustness during identification. The proposed reliable prediction method enables direct deployment on legacy HVAC systems and simultaneously establishes a foundation for embedded MPC controllers, enhancing operational efficiency to accelerate building decarbonization.

In this study, the lattice Boltzmann method (LBM) and the immersed boundary (IB) method are employed to quantitatively investigate the dynamics of circulating tumor cells (CTCs) at the cellular scale, and their interactions with red blood cells, platelets and microvascular wall are analyzed based on the obtained data. This reveals that CTC adhesion most likely occurs in the constricted vessels as the Reynolds number is around 0.01. An increase in hematocrit leads to enhanced adhesion, and cell stiffness influences the probability of adhesion. Furthermore, the activated platelets adhering to the CTCs exacerbate the metastatic spread, so the role of platelets in the deformation, adhesion and survival of tumor cells actively arrested by the endothelial cells is crucial. The findings in this work provide important quantitative insights into the underlying mechanisms of cancer metastasis.

An embedded hybrid distributed jet/pin-fin microchannel (JPM) heat sink with flow boiling visualization is constructed in the silicon base to enhance the chip-level heat dissipation. The flow boiling heat transfer characteristics of deionized water in JPM heat sink with jet Reynolds numbers (Re-j) of 244 similar to 732 and inlet subcoolings (Delta T-sub) of 20 degrees C similar to 60 degrees C are experimentally investigated and compared with those in distributed jet/smooth microchannel (JSM) heat sink. Two-phase flow patterns in JPM and JSM are simultaneously captured by a high-speed microscope camera. It is found that compared with JSM, critical heat fluxes for JPM are significantly enhanced by 27.7 %similar to 70.8 % due to the effective prevention of reverse flow and local dry-out. Specifically, JPM achieves an extremely high critical heat flux of 1098 W/cm(2) at a small pressure drop of 4.2 kPa when Re-j = 732 and Delta T-sub = 40 degrees C. Moreover, JPM can increase the heat transfer coefficient by 33.4 %similar to 51.6 % and decrease the effective thermal resistance by 22.8 %similar to 32.1 % due to more nucleation sites and larger heat transfer surfaces existing in JPM than in JSM. Meanwhile, better flow boiling stability and base temperature uniformity are obtained for JPM because its pin-fin structures can enhance the flow disturbance, promote the phase uniform distribution, and prevent the reverse flow. Particularly note that, although the enhancement in heat transfer is at the cost of the increase in pressure drop, JPM has superior comprehensive thermal-hydraulic performance than JSM, with PECs for JPM compared to JSM being 1.18 similar to 1.29 under different conditions. This study provides a more efficient embedded two-phase electronic cooling scheme by combining pin-fin microchannel with distributed jet impingement.

Nanofluids have a wide range of applications due to its excellent thermal properties (density, thermal conductivity and heat capacity), however, the mechanisms of thermal properties enhancement for nanofluids are still debatable. In this work, the study is focused on the effects of temperature, particle concentration and surface property (hydroxylated silica or hydrogenated silica) on the thermal properties of silica/1,8-octanediol (ODL) nanofluid using the molecular dynamics (MD) simulations. It reveals that the different molecular orientation of interfacial layers formed by 1,8-ODL on the silica surface cause the differences in its thermal properties: the nanofluid with hydroxylated silica possesses a higher density and a higher thermal conductivity, while the nanofluid with hydrogenated silica possesses a higher heat capacity. Moreover, the effects of temperature and particle concentration are also investigated in this study. As the temperature increases, the thermal conductivity enhancement changes nonmonotonically and presents a maximum, which results from the combination of the limited diffusion of 1,8-ODL molecules and the adsorption-desorption of molecules in the interfacial layer. The heat capacity enhancement of nanofluids increases with temperature can be attributed to the elevated interfacial thermal resistance between 1,8-ODL and silica. With a low silica concentration, the heat capacity of nanofluids can exceed that of pure 1,8-ODL due to the existence of interfacial layer. The findings in this work emphasize the important role of interfacial layer and molecular diffusion characteristics in enhancing the thermal properties of nanofluids.

Cancer remains one of the leading causes of death worldwide, with metastasis being the main contributor to its high mortality. In this study, based on the immersed boundary-lattice Boltzmann method, one blood flow model considering cell adhesion in microvasculature is established at the cellular scale to investigate the interaction mechanisms between circulating tumor cells (CTCs) and blood cells [red blood cells (RBCs) and platelets]. The results indicate that the interactions between CTCs and RBCs promote the margination behavior of CTCs. The distance between CTCs and the vessel wall directly influences their ability to form receptor–ligand bonds with endothelial cells, thereby affecting CTCs' adhesive performance. Meanwhile, platelets enhance the CTCs' adhesion to the vessel wall and reduce the mechanical stress exerted on CTCs, ultimately decreasing the likelihood of their rupture and dissolution. This work quantitatively elucidates the complex interactions among CTCs, RBCs, and platelets, providing new potential directions for cancer treatment and prevention.