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The gravity–capillary evaporation phase change in microgrooves inside a heat pipe is experimentally investigated by a visualization system. The evaporation regime, startup temperature response, and evaporation thermal resistance for gravity–capillary evaporation are evaluated and compared with those for capillary evaporation. The results identify oscillatory motion of vapor–liquid interface for gravity–capillary evaporation in rectangular microgrooves arising from the competition between gravity, the capillary force, and the shear force. In addition, the presence of gravity introduces the transition from fin–film evaporation regime to corner–film evaporation regime in rectangular microgrooves, and hence results in an overshoot startup and temperature oscillation during the process of gravity–capillary evaporation. Interestingly, the corner–film evaporation improves the evaporation phase change performance in the microgrooves. © 2018 American Institute of Chemical Engineers AIChE J, 65: 1119–1125, 2019 [ABSTRACT FROM AUTHOR]

A numerical model was developed on the diffusion, migration and concentration distribution of exhausts and particles in atmospheric wind field at Antarctica. The characteristics of diffusion, migration and concentration distribution of exhausts and particles generated by fuel engine was studied using computational fluid dynamics combined with particle dynamics and DSMC (direct simulation Monte Carlo) method. The results show that the mass concentration of NO2 and exhaust temperature decrease rapidly near the exhaust pipe, while the exhaust diffusion decrease slowly away from the exhaust pipe. The collision and cohesion reduces the concentration of the particles in atmospheric wind field, with the reduction of the influence region by the diffusion of particles in the atmospheric environment It increases the mass concentration of particles in each location by the increase of mass flow rate and initial size of the particles and the decrease of the atmospheric wind velocity. Althrough the influence radius varies with the particle flow rate, initial size and wind velocity, the mass concentration of particles meets the national standard at the distance of about 40 m away from the particle diffusion source. [ABSTRACT FROM AUTHOR]

A model of vapor condensation on a solid surface is developed and numerically analyzed using the free-energy lattice Boltzmann method. Based on the model, the condensation phase change on hydrophobic, hydrophilic and gradient surfaces are simulated with a particular focus on the condensation on a gradient surface. The droplet nucleation, growth, deformation, coalescence and motion during the condensation on a gradient surface are investigated. The present simulation reproduces the self-propelled dropwise condensation on a gradient surface, the film condensation on a hydrophilic surface and the conventional dropwise condensation on a hydrophobic surface. The results indicate that the condensed droplets on a gradient surface can be swept in time to provide a favorable condition for the subsequent condensation. On a smooth gradient surface, owing to the unbalanced wetting force, the vapor condenses into a thin film firstly and then fractures into droplet nucleation as the condensation process goes on. The larger wettability gradient results in a larger amplitude oscillation of condensation rate and a slighter variation of surface coverage. [ABSTRACT FROM AUTHOR]

The condensation flow patterns of ethanol–water mixture in a wide range of ethanol mass concentration inside a hydrophobic microchannel is experimentally studied via a high speed imaging system. The effects of channel surface wettability and ethanol concentration on flow condensation are compared and discussed. The experimental results indicate that the surface hydrophobic modification and ethanol concentration play a significant role in the flow condensation of mixture in a microchannel. The droplet condensation appears almost the whole two-phase flow region when the water steam is the main component, in which the droplet flow, droplet-streak flow, droplet-annular flow, droplet-injection flow and droplet-slug/bubble flow occur sequentially in a hydrophobic microchannel. With increasing ethanol concentration, the droplet-slug/bubble flow after droplet-injection flow disappears and is replaced by the pure slug/bubble flow. When the ethanol vapor is the main component, the droplet condensation almost disappears, and the annular-streak flow, annular flow, injection flow and slug/bubble flow appear sequentially along the flow direction. Both an increase in vapor Reynolds number and a decrease in ethanol concentration cause the injection location move toward the channel outlet. In addition, the surface hydrophobic modification introduces the droplet condensation, which is beneficial for the flow condensation heat transfer. [ABSTRACT FROM AUTHOR]

Siyuan Liu, Chengbin Zhang and Fen Guo contributed equally to this work. Reference 1 Liu S, Zhang C, Guo F. A systematical genome-wide analysis and screening of WRKY transcription factor family engaged in abiotic stress response in sweetpotato. [Extracted from the article]

• LHS is proposed to enhance thermal performance of AGHP under intermittent heating. • Thermal performance of AGHPs with three LHS modes are experimentally investigated. • Introduction of LHS unit into AGHP reduces the temperature of heat source by 27.4%. • The presence of LHS unit greatly enhances the thermostat performance of an AGHP. • Temperature homogenization of AGHP & LHS units becomes worse as heat load increases. Heat pipe coupled with phase change material (PCM) based latent heat storage (LHS) is a significant thermal management system that can efficiently control the intermittent high heat loads of electronic devices. Herein, an axially grooved heat pipe-LHS (AGHP&LHS) system has been proposed. The influence of LHS units and their location on dynamic temperature response of AGHP has been investigated both experimentally and theoretically. The effect of filling rates of phase change materials (PCMs) as well as cooling temperature on thermal response of the AGHP has been compared and analyzed. Results indicate that the LHS effectively stabilizes the heat source temperature under the intermittent heating process, enhances the thermostat performance and brings the temperature uniformity in AGHP. In addition, LHS units arranged at the evaporator section are optimal for AGHP under intermittent heat load conditions, reducing the heat source temperature by 27.4% and prolonging the melting time by 81.5%. As the heat load increases, the melting time of AGHP&LHS system becomes shorter, and the overall temperature uniformity is worsened. In particular, the melting time is prolonged by 34.8% for AGHP&LHS system with PCM filling rate of 89% than that of 44% filling rate. [ABSTRACT FROM AUTHOR]

Methanol-based physical absorption with good capture ability of CO 2 and H 2 S is commercially used in the acid gas removal (AGR) unit. However, the huge energy consumption for cooling methanol and acid gas prevent its massive development. An increasing number of experimental and numerical work has been reported on the benefits of using nanofluid to improve the CO 2 absorption at room temperature to lower the energetic cost. The purpose of this paper is to realign the study with the industrial process by confronting the approach reported in the publications and conclusions with the reality of the overall industrial operations. A brief discussion on the industrial operations of CO 2 removal by methanol solution without nanoparticles is firstly given, with the observations and technical difficulties involved. Then, the available of the Rectisol-based variants for CCS will be reviewed, including the issues of designed models, simulations and the compute of absorption performance. Subsequently, the benefit of nanoparticles to the Rectisol process is studied. Finally, a critical review is performed on the results available in the publications and will propose several suggestions to their evaluation for industrial application. It is suggested that using nanoparticles to enhance absorption and desorption process of CO 2 capture has big room for mature because of the limited data under industrial conditions. • The industrial operations of CO 2 removal by methanol solution without nanoparticles is briefly discussed. • The available of the Rectisol-based variants for CCS is completely reviewed. • The benefit of nanoparticles to the Rectisol process is predicted. • A critical review is performed on the results available in the publications. • Several suggestions to the research for industrial application are proposed. [ABSTRACT FROM AUTHOR]

Slippery liquid-infused porous surfaces are vulnerable to lubricant depletion caused by three major factors encompassing, the evaporation, cloaking, and shearing. Herein, lubricant-infused iron palmitate surfaces (LI-IPSs) are presented addressing the challenges of (1) evaporation-driven lubricant depletion enabled by the immensely clustered micro-/nano-structures of iron palmitate surface (IPS), (2) completely suppressing the wetting ridge even with miscible water-oil combinations enabled by only the handful uptake of oil by IPS. The apparent contact angle θa and sliding angle α of water on LI-IPSs are 98° ± 2° and 3° ± 1°, respectively. Under evaporation-driven lubricant depletion analysis, the shelf-durability of LI-IPSs has been found to last for 10 days in partially open environment at the ambient temperature (25 °C). The heat fluxes and condensate fluxes have been determined. The highest condensate flux on LI-IPSs (14 kgh−1 m−2) is ascribed to the dropwise condensation mode with efficient droplet dynamics. However, the service durability of LI-IPSs has lasted only for 50 ± 5 min under rigorous condensation, which is further addressed by developing a LI-IPS prototype. Based on the excellent wicking capability of IPS, LI-IPS prototype is capable of maintaining the dropwise condensation unless the oil is available in the oil tub. The LI-IPS prototype has been subjected to open environment at ambient temperature for 168 h, and even after that, the stable dropwise condensation has been achieved with the same range of droplet speed as had been observed in the first hour. Meantime, the high condensation heat fluxes at various subcooling temperatures are obtained, justifying the promising ability of LI-IPS. [ABSTRACT FROM AUTHOR]