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The Effect Of Viscosity On The Erosion Of Gradient- Zone In A Laboratory Solar Pond

Electronic Theses of Indian Institute of Science

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Title The Effect Of Viscosity On The Erosion Of Gradient- Zone In A Laboratory Solar Pond
 
Creator Pradhan, Sudeep S
 
Subject Mechanical Engineering
Viscosity
Gradient Zone
Solar ponds
Erosion
Double-diffusive Phenomena
Double Diffusion
Carboxy Methyl Cellulose (CMC)
 
Description Double diffusive phenomena occur in many natural systems and in a variety of engineering applications, such as solar ponds. In a solar pond, the erosion of gradient zone due to convection and diffusion is the main cause of inefficiency and hence, requires lot of maintenance. In this thesis, control of erosion of the gradient zone in a solar pond situation has been studied through experiments and transient numerical simulations. A laboratory solar pond was setup in a tank of size 19cm X 19cm X 19cm, and was heated from below. A polymer additive, Carboxy Methyl Cellulose (CMC) was used to increase the viscosity of the working fluid. With 0.01% CMC, viscosity enhancement of the working fluid by 25 to 30 times was achieved, without changing any other properties. The transient momentum, energy and species conservation equations along with continuity equation were solved numerically, using the SIMPLER algorithm with 2 mm grid spacing.

The experiments conducted with the addition of CMC, showed delays in the onset of convection and reduced erosion of the gradient zone. The erosion rates obtained from the numerical simulations agreed with the experimental observation. The impact of viscosity on the onset of convection, kinetic energy, convection pattern, frequency of bursts and erosion rate of the gradient zone, were simulated. Numerical simulations revealed that, there is a nonlinear relationship between the viscosity and erosion rate of the gradient zone. Increase in viscosity by a factor of 15 reduced the erosion of gradient zone completely, indicating the dominant role played by Turbulent entrainment.

The present work indicates that the control of erosion of gradient zone in solar pond using the polymer additive shows lot of promise. The use of the polymer additive as a method to increase viscosity will lower the maintenance costs and, increase the reliability and efficiency of solar ponds, with less than 5% increase in the initial cost.
 
Publisher Indian Institute of Science
 
Contributor Srinivasan, J
 
Date 2006-08-24T07:56:23Z
2006-08-24T07:56:23Z
2006-08-24T07:56:23Z
2000-08
 
Type Electronic Thesis and Dissertation
 
Format 2592339 bytes
application/pdf
 
Identifier http://etd.iisc.ernet.in/handle/2005/233
null
 
Language en
 
Rights I grant Indian Institute of Science the right to archive and to make available my thesis or dissertation in whole or in part in all forms of media, now hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation.