Fatemeh Hassanipour

Numerical Simulation of Capillary Convection with Encapsulated Phase-Change Particles

This study presents preliminary numerical simulations of forced convection with encapsulated phase-change material (EPCM) particles suspended in water, flowing through a square cross-section duct with top and bottom isoflux surfaces. The EPCM particles fit snugly in the channel, mimicking the flow of red blood cells and plasma in alveolar capillaries. Results for particles of different diameters show the snug fitting to yield enhanced heat transfer. The numerical results also seem to indicate the existence of an optimum number of particles for maximum heat transfer coefficient, a result of the interplay of flow circulation and heat transfer competition as the number of particles is changed in the channel.

Heat Sink With Stacked Multi-Layer Porous Media

Previous studies have shown that stacked multi-layer mini-channels heat sinks with square or circular channels have advantages over traditional single layered channels in terms of both pressure drop and thermal resistance. In this work, porous media is used in the multi-layered stacked mini-channels instead of square or rectangular channels and the effect of the same on pressure drop and thermal performance is studied. Porosity scaling is done between the layers of porous media and is compared with unscaled stacked multilayer channel. Porosity scaling allows the porosity to vary from one layer to the next layer and could result in a lower pressure drop and better thermal performance.Copyright

Experimental Analysis of Nanofluid Slurry Through Rectangular Porous Channel

One of the limitations in evolution of energy-efficient heat transfer fluids in industrial application is their low thermal conductivity. Among the emerging heat transfer technologies of today are fluid additives based on metallic nanoparticles. Previous studies show that Matalic nano particles increase the heat transfer rate by their thermal conductivity. This experimental study investigates the heat transfer behavior of nanofluid slurry through metal foam. Using suspending Aluminum Oxide nanoparticles (AL2O3) in fluid flowing through porous medium leads to have an even greater augmentation in heat transfer rate. Metal foams (porous media) enhance heat transfer rate not only by their high thermal conductivity and also by their mixing effect. When these two subjects come together even more interesting behaviors happen. This paper presents the result of heat transfer enhacment by slurry of metal nanoparticles in porous media in various of flow velocities, heat flux and porous media structures e.g. PPI and particle concentration of nanofluid.Copyright

Virtual Thermal Sensing and Control of Heat Distribution Using State Estimation

Many industrial applications require or can be improved by strict control of the temperature distribution on a surface. This initial investigation presents modeling and control of heat flow on an aluminum plate. Temperature distribution is modeled using a dense equivalent electrical circuit. An observer is designed based on the model to estimate the temperature distribution on the plate. The estimation is used in a controller to regulate the temperature of a desired point on the plate, given discrete heat input elements but no cooling elements. Experiments are conducted to compare the realism of the heat flow model and efficacy of the control method with experimental data. Results show that the steady state error between the actual and estimated temperatures at different points on the surface is always less than 0.5°C, which indicates accurate estimation of the temperature. The RMS error between desired and actual temperatures through all experiments is less than 2°C which indicates fast regulation and low steady state error.Copyright

New Bio-Inspired, Multiphase Forced Convection Cooling by ABS Plastic or Encapsulated Paraffin Beads

Preliminary experimental results of forced convection by octadecane paraffin (encapsulating phase-change material (EPCM)) particles, acrylonitrile butadiene styrene plastic particles, or by clear (of particulates) water flowing through a heated parallel-plates channel are reported. The objective is to investigate the mixing effect of the particles vis-a-vis the latent heat effect. The particle concentration is kept at 3% in volume. The results, in terms of surface-averaged channel temperature and heat transfer coefficient for different fluid speed and heat-flux, indicate the mixing effect to account from 19% to 68% of the heat transfer enhancement produced by using EPCM particles. Hence particle mixing, even at a very low particle concentration, is an effective convection mechanism.

Mathematical Modeling of Mammary Ducts in Lactating Human Females

This work studies a model for milk transport through lactating human breast ducts and describes mathematically the mass transfer from alveolar sacs through the mammary ducts to the nipple. In this model, both the phenomena of diffusion in the sacs and conventional flow in ducts have been considered. The ensuing analysis reveals that there is an optimal range of bifurcation numbers leading to the easiest milk flow based on the minimum flow resistance. This model formulates certain difficult-to-measure values like diameter of the alveolar sacs and the total length of the milk path as a function of easy-to-measure properties such as milk fluid properties and macroscopic measurements of the breast. Alveolar dimensions from breast tissues of six lactating women are measured and reported in this paper. The theoretically calculated alveoli diameters for optimum milk flow (as a function of bifurcation numbers) show excellent match with our biological data on alveolar dimensions. Also, the mathematical model indicates that for minimum milk flow resistance the glandular tissue must be within a short distance from the base of the nipple, an observation that matches well with the latest anatomical and physiological research.

Mathematical analysis of mammary ducts in lactating human breast.

This work studies a simple model for milk transport through lactating human breast ducts, and describes mathematically the mass transfer from alveolar sacs through the mammary ducts to the nipple. In this model both the phenomena of diffusion in the sacs and conventional flow in ducts have been considered. The ensuing analysis reveals that there is an optimal range of bifurcation numbers leading to the easiest milk flow based on the minimum flow resistance. This model formulates certain difficult-to-measure values like diameter of the alveolar sacs, and the total length of the milk path as a function of easy-to-measure properties such as milk fluid properties and macroscopic measurements of the breast. Alveolar dimensions from breast tissues of six lactating women are measured and reported in this paper. The theoretically calculated alveoli diameters for optimum milk flow (as a function of bifurcation numbers) show excellent match with our biological data on alveolar dimensions. Also, the mathematical model indicates that for minimum milk flow resistance the glandular tissue must be within a short distance from the base of the nipple, an observation that matches well with the latest anatomical and physiological research.

Experimental analysis of phase change material slurry through porous channel

Among the emerging heat transfer technologies of today are fluid additives based on micro-encapsulated phase-change materials (MPCM). Unfortunately, very small particles do not produce a strong mixing effect in the liquid, thus missing out on a source of efficiency in the heat transfer process. Also, particles flowing far from the channel heat exchange surfaces do not efficiently participate in heat transfer. In this study, phase change material slurry is used in conjunction with porous media (metal foam) to improve the heat transfer rate. The experimental results show that addition of porous media increases the heat transfer rate significantly. Enhancement in heat transfer happens mainly due to the departure of un-melted particles from center of the channel toward the heated surface area by mixing processes in the porous channel. Experimental tests for various wall heat fluxes, inlet velocities and particle concentration are carried out. Also the effect of porous media structure on heat transfer enhancement and mixing phenomena is studied. Heat transfer enhancements are compared for two cases of (1) micro-size flow circulation inside the pores and (2) large scale mixing effects by inserting baffles in the channel. The results show that small circulations of flow due to the porous media has dominant effect on the heat transfer rate compared with the large-scale circulations happening by baffles.

Effect of porous media properties on heat transfer in triangular porous duct

This study presents an analysis of forced convection in a porous triangular channel. The flow is laminar, fully developed and assumed to have constant properties. The porous channel has an isotropic matrix and the boundary conditions are fixed with constant temperature. In this paper, accurate analytical solutions are presented to determine the effects of apex angle and porous media properties on the velocity and temperature distribution in a triangular channel along with the friction factor fRe, and Nusselt number NuT. The presentaion includes numerical features of the exact series solution using Brinkman’s model. Numerical results for dimensionless average temperature and velocity are presented for various porosities, permeabilities and apex angles.Copyright

Heat Transfer Enhancement by Slurry of Phase Change Material Through Rectangular Porous Channel

This study attempts to take advantage of porous media with high conductivity and the latent heat capacity of phase change material together to enhance the overall heat transfer rate. A 3-D laminar model of a rectangular porous channel with high thermal conductivity and constant wall heat flux is chosen to see the enhancement of heat transfer when used in conjunction with the phase change material slurry. Numerical simulations for various wall heat fluxes and inlet velocities are carried out. The heat transfer coefficient along the heated surface of the channel is compared when adding micro-encapsulated phase change material to the flow passing through porous channel. There is a significant heat transfer enhancement when using phase change material slurry through porous channel, only under specific conditions of heat fluxes, inlet velocities and the particle concentrations. This study also investigates the effect of various porous media properties e.g. porosity and permeability on the heat transfer coefficient when applied with slurry of phase change material.© 2011 ASME