APPLICATION OF NANOFLUIDS IN SECONDARY REFRIGERATION SYSTEMS / APLICAÇÃO DE NANOFLUIDOS EM SISTEMAS SECUNDÁRIOS DE REFRIGERAÇÃO

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

04/05/2012

RESUMO

The application of nanofluids as secondary fluids in vapor compression refrigeration systems is studied with the development of a lumped-parameter thermodynamic model. When a nanofluid is used as a heat transfer fluid, its thermal conductivity and viscosity increase, when compared with the corresponding properties of the base fluid. The irreversibilities due to heat transfer and due to friction decrease and increase, respectively. After irreversibility is calculated for each component, the method of structural coefficients of internal bonds is applied to determine the effect of the volumetric concentration of nanoparticles in the secondary fluid on the system¿s global irreversibility, taking into account the interrelations of the analyzed structure. To estimate the practical limits of thermal irreversibility reduction with nanofluid application, an optimization of operational cost was proposed, based on thermoeconomic analysis, and considering the application of the new secondary fluid on the system, without additional modifications. Based on the proposed model, which was verified by experimental data, an typical operation condition was simulated. Through partial optimization, the minimum operational cost is determined for a simple variation of volumetric concentration of nanoparticles. The results of the optimizations furnish different optimal concentration values for different scenarios. Additionally, an study of nanofluid application in a shell and tube evaporator was included. The evaporator was simulated from a detailed thermodynamic model. Experimental data were collected to validate the model.

ASSUNTO(S)

nanofluidos nanofluids sistema indireto de refrigeracao indirect vapor compression refrigeration systems coeficiente estrutural structural coefficent

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