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Title:	Exergy analysis of open microchannels embedded within permeable surface
Authors:	Mohammad Hossein Yazdi (P42494)
Supervisor:	Kamaruzzaman Sopian, Prof. Dato' Dr.
Keywords:	Fluid dynamics Magnetohydrodynamics Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	8-Jun-2012
Description:	Magnetohydrodynamic (MHD) in microfluidics has been recognized as a mechanism for controlling the microstructure of materials and fluid behaviour. Open microchannels having their top side open to the ambient air are able to give advantages, such as in maintaining the physiological conditions for normal cell growth. Considering both MHD and open microchannels leads us to this new design of fluid control in micro systems. Hence, the objective of this thesis is to design and develop a new technique of reducing exergy losses of the external viscous MHD flow of an electrically conducting fluid based on open parallel microchannels embedded within permeable surface. First, by using dimensionless similarity variables, fundamental equations of the problem are transformed into ordinary differential equations which are solved numerically using an explicit Runge-Kutta (4, 5) formula, the Dormand-Prince pair and the shooting method. Next, the rate of entropy generation is formulated by an integral of local entropy generation using Entropy Based Surface Microprofiling (EBSM). The benefits of wall shear stress reduction due to the slip-flow conditions can be more important than the higher irreversibility arising from added microchannel area. The results based on continuous moving surfaces indicate that an increase in the number and width of the open parallel microchannels can reduce exergy losses. In addition, the permeability effect on the wall shear stress is negligible when the slip coefficient, K is more than 2. As an advantage of this configuration, especially in external flow past a stationary surface (when u∞ is not zero), the fluid receives a push from the applied magnetic field such that the fluid velocity increases and the system acts as a MHD micro pump which is a non-mechanical pump. If the magnetic parameter M varies from 0 to 1, it is capable of increasing the velocity more than 100% over surface structure. The wall shear stress increases with M and the nonlinear surface velocity parameter n while decreases with K and the mass injection. An increase in slip coefficient K from 0 to 1 can increase the heat transfer rate on the stationary surface more than 100% but shows a decreasing effect over continuous moving surface about 20%. Nevertheless, the viscous dissipation term can be negligible for high-slip coefficients (K>2). The results are able to be applied on a variety of micro systems for reducing the energy availability losses.,Certification of Master's / Doctoral Thesis" is not available
Pages:	172
Call Number:	TA2040.Y349 2012 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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