14 research outputs found

    Numerical Simulation and Optimization of the Melting Process of Phase Change Material inside Horizontal Annulus

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    Latent heat storage (LHS) technologies adopting phase change materials (PCMs) are increasingly being used to bridge the spatiotemporal mismatch between energy production and demand, especially in industries like solar power, where strong cyclic fluctuations exist. The shell-and-tube configuration is among the most prevalent ones in LHS and thus draws special attention from researchers. This paper presents numerical investigations on the melting of PCM, a paraffin blend RT27, inside a horizontal annulus. The volume of fluid model was adopted to permit density changes with the solidification/melting model wherein natural convection was taken into account. The eccentricity and diameter of the inner tube, sub-cooling degree of the PCM, and the heating-surface temperature were considered as variables for study. Through the evaluation of the melting time and exergy efficiency, the optimal parameters of the horizontal annulus were obtained. The results showed that the higher the heating boundary temperature, the earlier the convection appeared and the shorter the melting time. Also, the different eccentricity and diameters of the inner tube influenced the annulus tube interior temperature distribution, which in turn determined the strength and distribution of the resulting natural convection, resulting in varying melting rates

    Stochastic induction time of attachment due to the formation of transient holes in the intervening water films between air bubbles and solid surfaces

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    Bubble attachment to hydrophobic solid surfaces is influenced by the liquid film instability. Inclusion of transiently formed holes within the film rather than the so-called hydrophobic force in the theory is expected to better describe and explain film rupture and triple contact line formation in the bubble-surface attachment process. The significance of surface hydrophobicity and hole formation renders the stochastic nature of the induction time of attachment.A combination of high-speed video microscopy and theoretical analysis was applied to investigate the induction time of attachment and critical film thickness of air bubbles rising freely perpendicularly to silica surfaces of different hydrophobicities.Film rupture occurred statistically for shorter induction times and thicker films on the more hydrophobic surface, rejecting the conjecture of hydrophobic force. Computed results of the critical base radius of the transient holes causing film rupture were merged together nicely, independently of surface hydrophobicity. The paper sheds light on the significance of hydrophobicity on the attachment process by means of a novel and easily implemented methodology, without relying on the debatable hydrophobic force

    Consumer confidence in the safety of milk and infant milk formula in China

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    A series of food safety incidents related to domestically produced dairy in China harmed consumer confidence and caused a dramatic decrease in dairy consumption from 2008 to 2010. Compared with previous studies that mainly assessed consumer confidence in food or dairy in general, this study focused on 2 specific dairy products, milk and infant milk formula (IMF). Based on data from 934 Chinese consumers, confidence in the safety of milk and IMF was measured by using a multi-item scale with 2 dimensions—optimism and pessimism. We found that Chinese consumers were optimistic about the safety of milk and IMF but, at the same time, were concerned about the risks related to milk and IMF. Chinese consumers have less confidence in IMF than in milk. Structural equation modeling indicated that consumer trust in manufacturers and third parties in the dairy supply chain and confidence in other foods, such as meat and fish, can foster consumer confidence in the safety of milk and IMF, while the extent of recall of the melamine infant formula incident in 2008 and trait worry exert negative effects. In addition, consumers with more children or less family income are likely to be more confident in domestically produced IMF. These insights into consumer confidence and its determinants can assist dairy supply chains and regulatory institutions in formulating effective risk communication strategies to strengthen consumer confidence.</p

    Design and Optimization of Thermophotovoltaic System Cavity with Mirrors

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    Thermophotovoltaic (TPV) systems can convert radiant energy into electrical power. Here we explore the design of the TPV system cavity, which houses the emitter and the photovoltaic (PV) cells. Mirrors are utilized in the cavity to modify the spatial and spectral distribution within. After discussing the basic concentric tubular design, two novel cavity configurations are put forward and parametrically studied. The investigated variables include the shape, number, and placement of the mirrors. The optimization objectives are the optimized efficiency and the extended range of application of the TPV system. Through numerical simulations, the relationship between the design parameters and the objectives are revealed. The results show that careful design of the cavity configuration can markedly enhance the performance of the TPV system

    Experimental Study on the Combined Effect of Electromagnetic and Electrochemical Processes on Descaling and Anticorrosion

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    In this study, a circulating water experimental system was constructed to investigate the scale inhibition, scale removal, corrosion inhibition, and disinfection effects of industrial circulating water under the combined action of electromagnetic and electrochemical fields. The influence of these effects on water quality parameters and their scale inhibition and corrosion inhibition effects on hanging plate experiments were examined. Qualitative and quantitative analyses of scale samples were conducted using XRD (X-ray diffraction) and SEM (scanning electron microscopy), along with the evaluation of changes in water quality parameters (such as conductivity, hardness, Chemical Oxygen Demand (COD), turbidity, iron ions, and chloride ions) before and after the experiments. The results showed that after 360 h of circulation experiment, at a water temperature of 30 °C, electromagnetic field frequency of 1 kHz, electrochemical scale removal device voltage of 24 V, current of 10 A, and water flow rate of 0.6 m/s, the transformation of calcite to aragonite in CaCO3 scale samples occurred, with a 76.6% increase in aragonite content. Moreover, the conductivity decreased by 11.6%, hardness decreased by 42.0%, COD decreased by 59.7%, turbidity decreased by 48.1%, and chloride and iron ion concentrations decreased by 36.6% and 63.1%, respectively. The scale inhibition efficiency reached 53.8%, surpassing the effects of electromagnetic and electrochemical actions individually. These findings demonstrate that the combined action of electromagnetic and electrochemical fields can effectively enhance scale inhibition, scale removal, corrosion inhibition, and disinfection and algae removal effects

    Effect of cation intercalation on the growth of hexagonal WO₃nanorods

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    The growth mechanism of hexagonal tungsten oxide (h-WO₃) nanorods is investigated using molecular dynamics simulation. The results show that cation intercalation has a great impact on the formation of h-WO₃nanorods, reflected from the attractive interaction between the growth species (polytungstate anion, W10O32⁴¯) and crystal faces of (001) and (100). In particular, an appropriate amount of intercalated cations not only accelerate the crystal growth but also induce the formation of one-dimensional nanostructure of h-WO₃ nanorods along the direction of [001]. An excess of intercalated cations would be unfavorable to the evolution of rod shape. Ammonium ion (NH₄⁺) is found to be the most stable in a hexagonal tunnel, hence being effective in inducing the 1D morphology of h-WO₃. The main findings from the simulations are also verified by experiments

    A Novel miRNA Detection Method Using Loop-Mediated Isothermal Amplification

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    A novel ligation-based loop-mediated isothermal amplification has been developed for miRNA detection. Two stem-loop structure DNA linker A/B probes which hybridized with miRNA were designed to establish a rapid and ultrasensitive miRNA-LAMP system for miRNA detection. Target miR-200a was used to template the ligation of Linker A/B probes with SplintR Ligase and used as a dumbbell-shaped amplicon. By adding BIP/FIP and Bst 2.0 DNA polymerase, the LAMP reaction was carried out, which brought greatly improved amplification efficiency. The double-stranded DNA fluorescent dye EvaGreen was added for the detection of amplification product to achieve the quantification of the target miRNA. This method can detect miRNA in a linear range of seven orders of magnitude, with a detection limit of 100 fM. Therefore, this ultrasensitive miRNA-LAMP assay provides a new path for the highly sensitive quantitative analysis of miRNA, thereby bringing convenience to clinical diagnosis and prognostic research

    Consumer trust in the dairy value chain in China: The role of trustworthiness, melamine scandal, and media

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    This study provides a deep insight into Chinese consumer trust in the Chinese dairy value chain, as a lack of trust due to the 2008 melamine scandal has been widely recognized as a barrier to the development of the domestic dairy industry in China. Based on face-to-face interviews with 954 Chinese consumers in Beijing, Shanghai, and Shijiazhuang, this study measured consumer trust in farmers, manufacturers, retailers, the government, and third parties. Consumer trust was studied by measuring the effect of beliefs on the trustworthiness of actors (i.e., competence, benevolence, integrity, credibility, and openness), and current experiences regarding the melamine scandal and the media. The results showed that the level of trust in dairy chain actors varied. The government and third parties were relatively highly trusted, whereas retailers were considered less trustworthy. The importance of consumer beliefs about trustworthiness are different among actors. Consumer belief of competence determines trust in farmers and manufacturers. For retailers, the government, and third parties, respectively, benevolence, credibility, and openness are the most important factors. Trust in dairy chain actors is still strongly negatively affected by current experiences regarding the melamine scandal, even though it occurred more than 10 years ago. Using social media to directly provide more information and establish continuous daily communication with consumers could help manufacturers and third parties to strengthen consumer trust
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