NACREE : New Approach in Chemical Reactor for the Equipartition of Entropy – NACREE

NACREE finds origin in the observation that, surprisingly, there are no methodologies that allow the knowledge of the creation of irreversibility to be linked to the design of devices. This project aims to offer one. The methodology developed during the project will be applied to plug flow reactors in laminar regime. A direct exchanger system will be associated with the reactors. We will call hereinafter Reactive Converters (CR) the assembly formed by the reactor and the associated exchangers. NACREE aims to improve the match between sources and uses by proposing a method for designing and integrating CR based on entropy minimization. More exactly, it is a question of reducing the irreversibilities (i.e. the production of entropy) by an adapted writing of the source terms and to ensure the equipartition of these terms along the CR. The project's hypothesis is that this equipartition can be largely achieved by making the geometric design parameters of the reactor and the exchangers variable in space, as for example, for a cylindrical reactor, the evolution of the diameter along the axis. For this project, the potential gains from entropy reduction will be based on the study of the modification of the characteristic lengths of the reactor, local load of the catalyst, injection points of reagents, point of injection and withdrawal of utilities. These modifications aim at a triple reduction: that of the heating (or cooling) means, that of the pumping means and of the reagents used. The formulation of the entropy equipartition applied to a reactive system will first be reformulated in order to take these parameters into account. This formulation will be integrated into the modeling of the reactor. When modeling the reactor, it is necessary to have a detailed knowledge of the local exchange coefficients. As the geometries explored (both in the reactor and in the exchanger) are neither constant nor standard, NACREE requires recourse to computational fluid dynamics to calculate these coefficients in order to take into account the impact of geometric variations on the flows. From the simulations considered as numerical experiments, we wish to establish a set of empirical correlations allowing the rapid calculation of the exchange coefficients. These correlations will be used in the CR model. This optimization will be carried out using a single "objective" function which will be the creation of irreversibility according to the geometric parameters studied. This "objective" function will be the sum not of the results of the irreversibilities of the reactor alone but of all of the irreversibilities of the CR. The response surfaces method will be used as a robust and proven method of optimization because it results in the expression of a function that is easy to optimize. A key point of this project is validation by experience. The use of a model and controlled experience will validate the approach. For this, the choice of the consortium is oriented towards additive manufacturing in order to access precise realization of the calculated dimensions. Finally, in order to validate the approach and verify that the solutions proposed by the optimization are realistic, the energy integration of the utilities will be carried out under the constraint of the geometries studied. The purpose of this integration is twofold. Validate that the equipartition converges the system towards the Minimum Energy Required and establish a number of constraints that can be used in the model to constrain the parameters. Through this project we therefore wish to provide the bases for a general methodology for the design of reactors involving coupled transfers in order to obtain significant savings on primary energies and on reagents