42 research outputs found

    Pumping and heat transfer enhancement by wall's morphing

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    In a previous study, heat transfer enhancement using a deformable wall in a heat exchanger was demonstrated numerically using CFD calculations in liquid single-phase situation. This configuration allows the pumping function to be integrated within the heat exchanger itself. Based on these results, a prototype has been developed (but with different dimensions than in the numerical study) in which one of the walls constituting the channel is subjected to dynamic deformations in the form of a traveling wave. Electric heaters on the other wall heat the channel. Actuation is achieved by means of piezoelectric actuators. Experimentally, the pumping function is observed, for all frequencies of deformations and for two different fluids (water and HFE 7000). The heat transfer intensification is also shown, and this in two experimental configurations: - a pressure difference (which may be zero) between the inlet and outlet of the channel is imposed: in this configuration, the traveling wave imposes the flow-rate. The heat transfer enhancement is then due both to the increase of the flow-rate and the disruption of the thermal boundary layers generated by the wave; - a flow-rate is imposed with a mechanical pump: in this case actuation has no effect on the pumping, and the measured heat transfer enhancement is then due only to the effects of the imposed dynamic deformations. First experiments with the presence of boiling were also performed. It was found that boiling can occur even if the fluid does not reach the saturation temperature within the channel. A 100% increase in the mean heat transfer coefficient was found when actuating the channel wall.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

    Russia’s idea of the multipolar world order: origins and main dimensions

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    Contemporary international relations are rife with the ideological struggle over the potential nature of the rapidly changing world order. Two distinct paradigmatic positions have surfaced. One champions economic, cultural, and political globalization conducted under the leadership of the Western world. The other advocates a more particularistic approach that fends for a balance of interests, multiplicity of politico-cultural forms and multiple centers of international influence. The latter doctrine, often referred to as the multipolar world theory, is the subject of this paper. The discussion argues that the idea of a multipolar world order has emerged as Russia’s main ethical and ideological position advanced in the international arena. Its philosophical tenets buttress Russian society intellectually at home, providing the expedients to pursue the country’s foreign policy goals abroad. The paper examines a substantial value package with roots in both Russian and Western philosophy that sustains the multipolar world order theory

    Understanding scientific study via process modeling

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    This paper argues that scientific studies distinguish themselves from other studies by a combination of their processes, their (knowledge) elements and the roles of these elements. This is supported by constructing a process model. An illustrative example based on Newtonian mechanics shows how scientific knowledge is structured according to the process model. To distinguish scientific studies from research and scientific research, two additional process models are built for such processes. We apply these process models: (1) to argue that scientific progress should emphasize both the process of change and the content of change; (2) to chart the major stages of scientific study development; and (3) to define “science”

    About phenomenology and modeling of dropwise condensation

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