Moonis Raza Ally

BET model for calculating activities of salts and water, molar enthalpies, molar volumes and liquid-solid phase behavior in concentrated electrolyte solutions

Abstract Ally, M.R. and Braunstein, J., 1993. BET model for calculating activities of salts and water, molar enthalpies, molar volumes and liquid-solid phase behavior in concentrated electrolyte solutions. Fluid Phase Equilibria , 87: 213-236. This paper demonstrates the calculation of the activities of salts and water, excess properties and solid phase equilibria in aqueous media by applying the general properties of solutions to extensions of the Stokes-Robinson application of the Brunauer-Emmett-Teller (BET) adsorption isotherm. Such a comprehensive treatment provides a thermodynamically consistent method of obtaining equilibrium properties of moderately to highly concentrated (up to molten salt regime) aqueous solutions with as few as two parameters, plus a third parameter in the case of molar volumes. The present state of development allows treatment of electrolytes with common anions or common cations, but does not yet include reciprocal salt mixtures. Multicomponent aqueous solutions can be treated as pseudobinary if desired, by invoking the proposed mixing rules. The real advantage of the method lies in the use of a minimal number of parameters to represent a wide variety of thermodynamic properties with reasonable accuracy over relatively wide temperature and concentration ranges. This comprehensive treatment is verified through comparison of predicted results and experimental data on: water vapor pressure-temperature-composition behavior of aqueous LiBr and of (Li, K, Na)NO 3 mixtures; partial excess and molar volume-temperature-composition of aqueous LiBr and of (Li, K, Na)NO 3 mixtures; partial excess and integral molar enthalpy-temperature-composition of aqueous LiBr; phase equilibria of NaOH in aqueous solution.

Investigation of electrokinetic decontamination of concrete

Abstract Experiments have been conducted to investigate the capabilities of electrokinetic decontamination of conceret. Batch equilibration studies have determined that the loading of cesium and strontium on concrete may be decreased using electrolyte solutions containing competing cations, while solubilization of uranium and cobalt, that precipitate at high pH, will require lixiviants containing complexing agents. Dynamic electrokinetic experiments showed greater mobility of cesium than strontium, while some positive results were obtained for the transport of cobalt through concrete using EDTA and for uranium using carbonate. *Managed by Lockheed Martin Energy Research Corp. for the U. S. Department of Energy under contract DE-AC05-96OR22464.

Activity coefficients in concentrated electrolytes : a comparison of the Brunauer-Emmett-Teller (BET) model with experimental values

Abstract Electrolyte mean ionic activity coefficients, γ±, are calculated from the Stokes-Robinson application of the Brunauer-Emmett-Teller (BET) adsorption model for seven electrolytes (NaOH, HCl, KOH, CaCl2, LiCl, LiBr and Ca(NO2)3). Only two model parameters are needed, which are derived from water vapor pressure measurements. Results were compared with experimental mean ionic activity coefficients (γ±). Because the standard state for the BET model is the anhydrous electrolyte rather than the infinitely dilute solution, it is necessary to adjust for the differing standard states by comparing the BET and experimental γ± values at one ‘anchoring’ concentration. The higher this ‘anchoring’ concentration, the better is the agreement between the BET and experimental mean ionic activity coefficients over the entire concentration (molality, mol kg−1) range except at the two extremes of nearly pure water and nearly pure electrolyte. This is because the BET model lacks a finite limit at infinite dilution, and the experimental data are referenced to the infinite dilute solution. The BET model is well-behaved and in good agreement with experimental data on γ±.

Modeling the Electrokinetic Decontamination of Concrete

Abstract The decontamination of concrete is a major concern in many Department of Energy (DOE) facilities. Numerous techniques (abrasive methods, manual methods, ultrasonics, concrete surface layer removal, chemical extraction methods, etc.) have been used to remove radioactive contamination from the surface of concrete. Recently, processes that are based on electrokinetic phenomena have been developed to decontaminate concrete. Electrokinetic decontamination has been shown to remove from 70 to over 90% of the surface radioactivity. To evaluate and improve the electrokinetic processes, a model has been developed to simulate the transport of ionic radionuclei constituents through the pores of concrete and into the anolyte and catholyte. The model takes into account the adsorption and desorption kinetics of the radionuclei from the pore walls, and ion transport by electro-osmosis, electromigration, and diffusion. A numerical technique, orthogonal collocation, is used to simultaneously solve the governing co...

Liquidus Curves of NaNO3(aq) Calculatedfrom the Modified Adsorption Isotherm Modelfor Aqueous Electrolytes

Summary. The Stokes-Robinson modification of the Brunauer-Emmett-Teller (BET) adsorption isotherm is used to calculate the liquidus curve of NaNO3(aq) including the eutectic point and metastable phases. The method described here represents a simplified approach to predict the liquidus curves with sparse information.

On theAbraham equation for salt activities in concentrated solutions

SummaryIt is shown that the equations derived byVoigt andAbraham for the calculation of salt activities in concentrated solutions are equivalent and that they satisfy theGibbs-Duhem equation.ZusammenfassungEs wird gezeigt, daß die vonVoigt undAbraham zur Berechnung der Aktivitäten von Salzen in konzentrierten Lösungen hergeleiteten Gleichungen äquivalent sind und dieGibbs-Duhem-Beziehung erfüllen.

Modeling the electrokinetic transport of strontium and cesium through a concrete disk

A one-dimensional electrokinetic model has been developed to simulate the transport of cesium and strontium ions through a concrete disk. The model predicts the variation of the ion concentrations in the anolyte and catholyte. The sensitivity of the ion concentration in the anolyte and catholyte to the overall mass transfer coefficient and ion diffusion coefficient is investigated. Using reasonable values for the diffusion coefficient and the overall mass transfer coefficient, good agreement is obtained between the experimental and computed variations in the anolyte concentrations. The results for the catholyte concentrations are in qualitative agreement with the experimental observations. The variation in the pH in the anolyte and catholyte, and the voltage drop across the disk, are predicted by the model.

Testing and evaluation of electrokinetic decontamination of concrete

The goals and objectives of the technical task plan (TTP) are to (1) describe the nature and extent of concrete contamination within the Department of Energy (DOE) complex and emerging and commercial technologies applicable to these problems; (2) to match technologies to the concrete problems and recommend up to four demonstrations; (3) to initiate recommended demonstrations; and (4) to continue investigation and evaluation of the application of electrokinetic decontamination processes to concrete. This document presents findings of experimental and theoretical studies of the electrokinetic decontamination (EK) process and their implications for field demonstrations. This effort is an extension of the work performed under TTP 142005, ``Electroosmotic Concrete Decontamination. The goals of this task were to determine the applicability of EK for treating contaminated concrete and, if warranted, to evaluate EK as a potential technology for demonstration. 62 refs.

Ground Source Integrated Heat Pump (GS-IHP) Development

Between October 2008 and May 2013 ORNL and ClimateMaster, Inc. (CM) engaged in a Cooperative Research and Development Agreement (CRADA) to develop a groundsource integrated heat pump (GS-IHP) system for the US residential market. A initial prototype was designed and fabricated, lab-tested, and modeled in TRNSYS (SOLAR Energy Laboratory, et al, 2010) to predict annual performance relative to 1) a baseline suite of equipment meeting minimum efficiency standards in effect in 2006 (combination of air-source heat pump (ASHP) and resistance water heater) and 2) a state-of-the-art (SOA) two-capacity ground-source heat pump with desuperheater water heater (WH) option (GSHPwDS). Predicted total annual energy savings, while providing space conditioning and water heating for a 2600 ft{sup 2} (242 m{sup 2}) house at 5 U.S. locations, ranged from 52 to 59%, averaging 55%, relative to the minimum efficiency suite. Predicted energy use for water heating was reduced 68 to 78% relative to resistance WH. Predicted total annual savings for the GSHPwDS relative to the same baseline averaged 22.6% with water heating energy use reduced by 10 to 30% from desuperheater contributions. The 1st generation (or alpha) prototype design for the GS-IHP was finalized in 2010 and field test samples were fabricated for testing by CM and by ORNL. Two of the alpha units were installed in 3700 ft{sup 2} (345 m{sup 2}) houses at the ZEBRAlliance site in Oak Ridge and field tested during 2011. Based on the steady-state performance demonstrated by the GS-IHPs it was projected that it would achieve >52% energy savings relative to the minimum efficiency suite at this specific site. A number of operational issues with the alpha units were identified indicating design changes needed to the system before market introduction could be accomplished. These were communicated to CM throughout the field test period. Based on the alpha unit test results and the diagnostic information coming from the field test experience, CM developed a 2nd generation (or beta) prototype in 2012. Field test verification units were fabricated and installed at the ZEBRAlliance site in Oak Ridge in May 2012 and at several sites near CM headquarters in Oklahoma. Field testing of the units continued through February 2013. Annual performance analyses of the beta unit (prototype 2) with vertical well ground heat exchangers (GHX) in 5 U.S. locations predict annual energy savings of 57% to 61%, averaging 59% relative to the minimum efficiency suite and 38% to 56%, averaging 46% relative to the SOA GSHPwDS. Based on the steady-state performance demonstrated by the test units it was projected that the 2nd generation units would achieve ~58% energy savings relative to the minimum efficiency suite at the Zebra Alliance site with horizontal GHX. A new product based on the beta unit design was announced by CM in 2012 – the Trilogy 40® Q-mode™ (http://cmdealernet.com/trilogy_40.html). The unit was formally introduced in a March 2012 press release (see Appendix A) and was available for order beginning in December 2012.

Direct Evaporative Precooling Model and Analysis

Evaporative condenser pre-cooling expands the availability of energy saving, cost-effective technology options (market engagement) and serves to expedite the range of options in upcoming codes and equipment standards (impacting regulation). Commercially available evaporative pre-coolers provide a low cost retrofit for existing packaged rooftop units, commercial unitary split systems, and air cooled chillers. We map the impact of energy savings and peak energy reduction in the 3 building types (medium office, secondary school, and supermarket) in 16 locations for three building types with four pad effectivenesses and show the effect for HVAC systems using either refrigerants R22 or R410A