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Title: Solar pond studies: Phase III. Fifth semiannual progress report to the US Department of Energy

Abstract

The diffusion equation for salt gradient solar ponds has been modified to include the Soret effect (a thermal cross-effect due to the temperature gradient). The contribution of the Soret effect to the diffusion flux of salt is shown to be on the order of 4% in the winter and 28% in the summer for the UNM NaCl solar pond. The traditional stability criterion for solar ponds remains practically unchanged by the Soret effect. However, the contribution of non-constant properties (diffusion coefficient, thermal diffusivity and viscosity) - which have been neglected so far - seems to be significant. Saturated solar ponds are described by a system of differential equations which include the Soret effect, the formation and redissolving of crystals. The analytical solutions of this system are given for the steady-state and constant properties. A laboratory experiment using KNO/sub 3/ confirms the existence of a stable saturated gradient. Temperatures of up to 90/sup 0/C and temperature gradients of up to 2/sup 0/C/cm were used in the experiment without any sign of convective layers. A saturated gradient at steady state includes a super saturated region close to the surface which results in the fallout of crystals in that region. The diffusion fluxmore » of salt is thus balanced by a flux of crystals downwards and the net flux of salt is zero in a steady state.« less

Authors:
;
Publication Date:
Research Org.:
New Mexico Univ., Albuquerque (USA). Dept. of Physics and Astronomy
OSTI Identifier:
5427533
Report Number(s):
ALO-3977-5
DOE Contract Number:
EG-77-S-04-3977
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; SOLAR PONDS; MATHEMATICAL MODELS; THERMODYNAMICS; DIFFERENTIAL EQUATIONS; DIFFUSION; POTASSIUM NITRATES; SALINITY GRADIENTS; STEADY-STATE CONDITIONS; TEMPERATURE GRADIENTS; ALKALI METAL COMPOUNDS; EQUATIONS; EQUIPMENT; NITRATES; NITROGEN COMPOUNDS; OXYGEN COMPOUNDS; PONDS; POTASSIUM COMPOUNDS; SOLAR COLLECTORS; SOLAR EQUIPMENT; 141000* - Solar Collectors & Concentrators

Citation Formats

Bryant, H.C., and Rothmeyer, M.K.. Solar pond studies: Phase III. Fifth semiannual progress report to the US Department of Energy. United States: N. p., 1980. Web. doi:10.2172/5427533.
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Bryant, H.C., & Rothmeyer, M.K.. Solar pond studies: Phase III. Fifth semiannual progress report to the US Department of Energy. United States. doi:10.2172/5427533.
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Bryant, H.C., and Rothmeyer, M.K.. Thu . "Solar pond studies: Phase III. Fifth semiannual progress report to the US Department of Energy". United States. doi:10.2172/5427533. https://www.osti.gov/servlets/purl/5427533.
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@article{osti_5427533,
title = {Solar pond studies: Phase III. Fifth semiannual progress report to the US Department of Energy},
author = {Bryant, H.C. and Rothmeyer, M.K.},
abstractNote = {The diffusion equation for salt gradient solar ponds has been modified to include the Soret effect (a thermal cross-effect due to the temperature gradient). The contribution of the Soret effect to the diffusion flux of salt is shown to be on the order of 4% in the winter and 28% in the summer for the UNM NaCl solar pond. The traditional stability criterion for solar ponds remains practically unchanged by the Soret effect. However, the contribution of non-constant properties (diffusion coefficient, thermal diffusivity and viscosity) - which have been neglected so far - seems to be significant. Saturated solar ponds are described by a system of differential equations which include the Soret effect, the formation and redissolving of crystals. The analytical solutions of this system are given for the steady-state and constant properties. A laboratory experiment using KNO/sub 3/ confirms the existence of a stable saturated gradient. Temperatures of up to 90/sup 0/C and temperature gradients of up to 2/sup 0/C/cm were used in the experiment without any sign of convective layers. A saturated gradient at steady state includes a super saturated region close to the surface which results in the fallout of crystals in that region. The diffusion flux of salt is thus balanced by a flux of crystals downwards and the net flux of salt is zero in a steady state.},
doi = {10.2172/5427533},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jan 10 00:00:00 EST 1980},
month = {Thu Jan 10 00:00:00 EST 1980}
}
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Technical Report:
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DOI:  10.2172/5427533
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  • ;
    A finite-element heat transport program has been modified to model the thermal behavior for a cylindrically symmetric salt-gradient solar pond of the Rabl-Nielsen type. In this model transient phenomena as well as steady-state behavior can be studied. Results are presented for a model of the solar pond at the University of New Mexico and are compared with actual measurements. Time constants are determined from a study of thermal histories after commissioning and after turn off and from annual and daily variations.

  • ;
    A thorough account is given of a solar pond study underway at the University of New Mexico since 1975. This report consists of the Ph.D. dissertation of Federica Zangrando entitled Observation and Analysis of a Full-Scale Experimental Salt Gradient Solar Pond. The stability condition for a non-constant gradient, doubly-diffusive system is derived and a prescription for the routine detection of potential instabilities is presented. Techniques for handling unstable regions are described. Conclusions so far strongly support the viability of the solar pond concept. Salt gradient ponds appear to have a very definite niche in the ecology of energy production.

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  • The report summarizes significant audit, inspection, and investigative accomplishments for the reporting period which facilitated DOE management efforts to improve management controls and ensure efficient and effective operation of its programs. During this period, the Office of IG issued 52 audit and 7 inspection reports. For reports issued during the period, the Office made audit recommendations that, when implemented by management, could result in $554 million being put to better use. Management committed to taking corrective actions which is estimated to result in a more efficient use of funds totaling $22.4 million. IG actions in identifying attainable economies and efficienciesmore » in Departmental operations have recently provided a positive dollar impact of about $4 million per audit employee per year. Also, the Office of Inspections committed major resources reviewing the Secretary of Energy`s foreign travel. IG investigations led to 20 criminal convictions, as well as criminal and civil prosecutions which resulted in fines and recoveries of $29, 365,094. The Office also provided 27 investigative referrals to management for recommended positive action.« less