Morphotronics and Constructal Theory

Author(s):  
Germano Resconi
Keyword(s):  
Author(s):  
Rafael San Martin Moreira ◽  
Liércio Isoldi ◽  
jeferson Avila Souza ◽  
Elizaldo dos Santos

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Giulio Lorenzini ◽  
Simone Moretti

High performance heat exchangers represent nowadays the key of success to go on with the trend of miniaturizing electronic components as requested by the industry. This numerical study, based on Bejan’s Constructal theory, analyzes the thermal behavior of heat removing fin modules, comparing their performances when operating with different types of fluids. In particular, the simulations involve air and water (as representative of gases and liquids), to understand the actual benefits of employing a less heat conductive fluid involving smaller pressure losses or vice versa. The analysis parameters typical of a Constructal description (such as conductance or Overall Performance Coefficient) show that significantly improved performances may be achieved when using water, even if an unavoidable increase in pressure losses affects the liquid-refrigerated case. Considering the overall performance: if the parameter called Relevance tends to 0, air prevails; if it tends to 1, water prevails; if its value is about 0.5, water prevails in most of the case studies.


Author(s):  
Adriano Sciacovelli ◽  
Vittorio Verda ◽  
Cristina Amelio ◽  
Carlo Repetto ◽  
Gustavo Diaz

In this paper, the prototype of a circular Molten Carbonate Fuel Cell (MCFC) built in the laboratories of FN SpA Nuove Tecnologie e Servizi Avanzati is analyzed using a tridimensional computational fluid dynamic (CFD) model. The prototype is the result of FN and Politecnico di Torino activities developed for the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) within the framework of Ministry of Economic Development, MSE-ENEA. This model considers heat, mass and current transfer as well as chemical and electrochemical reactions. The results show that some inhomogeneous distributions in the reactants, causing non-optimal use of the reactant surfaces. An effective way to improve the distribution in current density consists in tracing tree shaped channels on the surface onto the distribution porous medium. In this paper Y shaped channels are adopted to improve the distribution of gas within the fuel cell and consequently to enhance the performance of the original design of the fuel cell. In addition, the configuration of the outlet of the anodic compartment is also investigated in order to further increase the performance of the fuel cell. The geometrical parameter identifying the topology of distribution channels are chosen accordingly to the constructal theory. The results show that significant improvements can be achieved. Power density is increased of about 6% when the tree-shaped channel is adopted. If a double anodic inlet is also considered the enhancement in the power density is of about 11% with respect to the initial configuration.


2008 ◽  
Vol 7 (2) ◽  
pp. 81
Author(s):  
L. A. O. Rocha ◽  
C. Biserni ◽  
E. Lorenzini

This work reports, according to Bejan’s Constructal theory, the geometric optimization of an elliptical cavity that intrudes into a solid conducting wall. The objective is to minimize the global thermal resistance between the solid and the cavity. There is uniform heat generation on the solid wall. The cavity is optimized for two sets of thermal conditions: isothermal cavity and cavity bathed by a steady stream of fluid. The solid conducting wall is isolated on the external perimeter. The total volume and the elliptical cavity volume are fixed while the geometry of the cavity is free to vary. The results show that the optimized geometrical shapes are relatively robust, i.e., insensitive to changes in some of the design parameters: the cavity shape is optimal when penetrates the conducting wall almost completely.


Author(s):  
Luiz A. O. Rocha ◽  
S. Lorente ◽  
A. Bejan

Author(s):  
E. J. Walsh ◽  
R. Grimes

The advances in microfluidics and microelectronics bring with them the need to provide new cooling solutions for many applications. A number of technologies are under development for forced convection cooling at the microscale. This short paper, through the new constructal theory of Bejan, presents the minimum velocity requirements of any such technology to be truly useful in a new design. Thus the theory presented in this paper, should form the first step in the design process of any new forced cooling technology for mini-micro scale applications. Furthermore, it is demonstrated that the use of the constructal theory provides a heightened level of understanding to the problem of forced convection, while simultaneously deriving the empirical correlations proposed in the literature over the past number of decades.


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