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Vol 5 - Issue 2

Entropy: Thermodynamics – Energy – Environment – Economy


List of Articles

Nicholas Georgescu-Roegen’s bioeconomics: a new alliance between the economy and the biosphere
Sylvie Ferrari

Bioeconomics is a new approach to the relationship between the economy and the environment developed by N. Georgescu-Roegen (1906-1994), a great economist of the 20th century who was also a mathematician, philosopher and historian of science. The economy, as a sub-system of the biosphere, is understood in a global ecological context. It is also inseparable from the historical dimension of the development of societies, given the limited access to a stock of resources (energy and matter) taken from the environment. The ultimate aim of this original approach is to reconcile economic development with ecological constraints and to lead the economy towards sufficiency.


Hydrogen wet combustion and “Water Vapor Pump-cycle”
Rémi Guillet, Jean-Pierre Hébert, Gérald Brunel

The so-called “water vapor pump” cycle is defined by the selective recycling of the water vapor carried by the combustion products at the outlet of the thermal machine by exchange of mass and heat between the exiting combustion products and the incoming atmospheric air. With hydrogen fuel, this form of wet combustion is capable of very high energy and ecological performance. In this context, we present here the Hydrometric Combustion Diagram (HCD) of hydrogen and apply this tool to anticipate the energy performance of this new fuel whose PCS exceeds its PCI by 18%. These expectations also concern the case of gas turbines in the case of wet combustion which, moreover, are, a priori, highly consuming additional water. The formation of atmospheric water plumes, the "cost" of its elimination, the possible residual pollution due to NOx are also presented, this concerning the use of hydrogen fuel in all thermal combustion machines, including in fuel cells. All applications combined and in a cogeneration context, wet combustion, of which the so-called “water vapor pump” cycle is part, increases the dew point temperature of the combustion products by approximately 10°C and promotes useful energy recovery. approaching 100% of the higher calorific value of the fuel (100% of the PCS). What is to be emphasized with hydrogen fuel.


Biomimicry, an avenue to explore for process engineering?
Eric Schaer, Frédéric Demoly, Jean-Claude André

The exponential growth in the use of digital technology is forcing changes in the engineering of material and energy transformation processes, not only in terms of training, but also in terms of inventions of various origins, to revitalize this discipline, which is subject to strong environmental constraints. This near-breakthrough situation needs to be translated into greater creativity before we can achieve breakthrough or incremental innovations. To achieve this objective, it is sometimes useful to bring together two normally disjoint fields to generate ideas that are robust enough to be applied. This article discusses this method, based on biomimicry. Can taking advantage of nature’s ingenuity foster the emergence of anthropocentric inventions and thus accelerate innovation in the field of process engineering? This is the question posed by the authors in their quest to illustrate the opportunities and advantages of such an approach, as well as its current limitations.


What training is needed for industrial research?
Eric Schaer, Frédéric Demoly, Jean-Claude André

A look at the curricula of many French engineering schools reveals that their global vision is reflected in educational categories geared towards theoretical, rational and deterministic generalist learning, with a focus on the main application targets. Links with industry are developed in large part through internships, which broaden the somewhat closed vision provided by their school. This situation has its roots in history, with the need to master mathematical models to design structures, weapons, bridges, factories, material and energy transformation processes, and so on. What we are witnessing is the decline of technological eras from coal to electricity to electronics, with an increasingly constrained environment and demands for ever more sophisticated devices, with ever shorter life spans, in a changing social context. The question posed in this reflection is to analyze whether the impact of the major trends we have just mentioned is likely to call into question, at least in part, the fundamentals of current training courses. What we are showing is the importance of rigorous concepts, which must nevertheless be extended in different ways to other fields, promoting creativity, imagination and agility to bring the engineer’s work closer to the social demand for new needs. For the time being, the authors see this as a flexible/adaptive approach that should encourage creative modes on the part of students, the mastery of doubt, interdisciplinarity and the management of complexity in the development of industrial processes.


Some analytical properties of moving averages. Application to the detection of trends in a signal
Jacques Padet

The analysis of very irregular processes is often based on the search for a trend, an average curve representing the general course of the observed phenomenon. If each people is more or less capable of drawing such a curve freehand, in an intuitive way, its objective determination is very delicate. The method of moving averages being one of the most used in the search for trends, we propose here to study some properties of these moving averages (essentially mean and variance, or standard deviation). We then show that they can be used to detect characteristic observation windows, leading to structural trends of the analyzed signal. The notion of tau-average (trend obtained by a moving average with a variable window) is also re-examined.

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