Lithium Nitrate Solution Research Articles

Synthesis and study of lithium triuranate Li2U3O10 · 6H2O

Li2U3O10 · 6H2O crystal hydrate was synthesized by the reaction between synthetic schoepite UO3 · 2.25H2O and aqueous lithium nitrate solution under hydrothermal conditions at 200°C. The composition and structure of the obtained compound were established, and its dehydration and thermal decomposition were studied, by chemical analysis, X-ray diffraction, IR spectroscopy, and scanning calorimetry.

Experimental evaluation of ammonia adiabatic absorption into ammonia–lithium nitrate solution using a fog jet nozzle

This paper presents the experimental assessment of the adiabatic absorption of ammonia vapour into an ammonia–lithium nitrate solution using a fog jet nozzle. The ammonia mass fraction was kept constant at 46.08% and the absorber pressure was varied in the range 355–411 kPa. The nozzle was located at the top of the absorption chamber, at a height of 205 mm measured from the bottom surface. The diluted solution flow rate was modified between 0.04 and 0.08 kg s−1 and the solution inlet temperature in the range 25.9–30.2 °C. The influence of these variables on the approach to adiabatic equilibrium factor, outlet subcooling, absorption ratio and mass transfer coefficient is analysed. The approach to adiabatic equilibrium factor for the conditions essayed is always between 0.82 and 0.93. Pressure drop of the solution entering the absorption chamber is also evaluated. Correlations for the approach to adiabatic equilibrium factor and the Sherwood number are given.

Subcooled and saturated boiling of ammonia–lithium nitrate solution in a plate-type generator for absorption machines

This paper presents the experimental heat transfer evaluation during subcooled and saturated boiling of ammonia–lithium nitrate solution in a fusion plate heat exchanger, acting as a vapor generator under operating conditions representative of single-effect absorption machines. The solution flow rate and outlet temperature were modified in the ranges of 0.041–0.083kg/s and 78–97°C, respectively. The region where vapor bubbles begin to arise is estimated using a correlation for the wall superheat required for the onset of nucleate boiling. Results show that subcooled boiling is present in the generator. The initial boiling temperature is about 3.1°C lower than the saturation temperature. The influence of the heat and mass fluxes on the boiling heat transfer coefficient is analyzed. The paper offers a correlation for the Nusselt number, including the subcooled and saturated boiling regions.

Experimental Investigation of Pool Boiling Heat Transfer in Ammonia–Water–Lithium Nitrate Solution

The nucleate pool boiling heat transfer coefficient of an NH3-H2O-LiNO3 mixture was investigated on a cylindrical heated surface at low pressure of 4 to 8 bar, low ammonia mass fraction of 0 < xNH3 < 0.3, and different heat fluxes. The lithium nitrate concentration of the solution was chosen in the range of 10–50% of mass ratio of lithium nitrate in pure water. The effects of concentrations, heat flux, and pressure on boiling heat transfer coefficient was studied. The results indicate that the heat transfer coefficient in the mixture decreases with increase in ammonia mass fraction, increases with the addition of lithium nitrate, and increases with an increase in heat flux and pressure in the investigated range.

Study of an ejector-absorption refrigeration cycle with an adaptable ejector nozzle for different working conditions

This paper presents a numerical model of an ejector-absorption (single-effect) refrigeration cycle with ammonia–lithium nitrate solution as working fluid, operating under steady-state conditions. In this cycle, the ejector is located at the absorber inlet replacing the solution expansion valve. The liquid–gas ejector entrains refrigerant vapor from the evaporator; this way the absorber pressure becomes higher than the evaporator pressure without any additional energy consumption. The objective of this numerical model is to evaluate the influence of the ejector geometry on the cycle performances and to determine the range of the heat source temperature in which it is convenient to use a practical ejector in the absorption cycle. The simulation is based on UA-ΔTlm models for separate heat transfer regions in a novel implementation using plate-type heat exchangers and this way the results are offered as a function of the external temperatures. This study focuses on evaluating the feasibility of an ejector whose nozzle area is adjustable while the rest of the ejector dimensions are fixed, thus being more feasible than complete variable geometry ejectors. The cycle performance is reported for different mixing tube constant diameters. Results of the simulation show that the use of an ejector allows, among others, to decrease the activation temperature approximately 9°C in respect to the conventional single-effect absorption cycle and increasing the COP for moderate temperatures. The variable ejector nozzle geometry is of profit for optimizing and controlling the cycle.

Experimental study of a thermochemical compressor for an absorption/compression hybrid cycle

An experimental study of a thermochemical compressor with ammonia–lithium nitrate solution as working fluid has been carried out. This compressor incorporates a single-pass adiabatic absorber and all the heat exchangers are of the plate type: absorber subcooler, generator and solution heat exchanger. The thermochemical compressor has been studied as part of a single-effect absorption chiller hybridized with an in-series low-pressure compression booster. The adiabatic absorber uses fog jet injectors. The generator hot water temperatures for the external driving flow are in the range of 57–110°C and the absorber pressures range between 429 and 945kPa. Experimental results are compared with a numerical model showing a high agreement. The performance of the thermochemical compressor, evaluated through the circulation ratio, improves for higher absorber pressures, indicating the potential of pressure boosting. For the same circulation ratio, the driving hot water inlet temperature decreases with the rise of the absorber pressure. The thermochemical compressor, based on an adiabatic absorber, can produce refrigerant with very low driving temperatures, between 57 and 70°C, what is interesting for solar cooling applications and very low temperature residual heat recovery. Efficiencies and cooling power are offered when this hybrid thermochemical compressor is implemented in a chiller, showing the effect of different operating parameters.

Effect of the NH3–LiNO3 concentration and pressure in a fog-jet spray adiabatic absorber

Abstract This paper presents the effect that both the ammonia concentration in an ammonia–lithium nitrate solution and the absorber pressure have on the adiabatic absorption of ammonia vapour by droplets generated by a fog-jet injector. The injector ensemble is located at 205 mm from the bottom of the absorber. The solution has an ammonia mass fraction varying from 0.419 to 0.586 and the absorber pressure varies from 429 to 945 kPa. This is representative of the operating conditions for conventional absorption chiller cycles, but also for advanced cycles such as those with a booster compressor located in series between evaporator and absorber. This leads to a higher than common pressure in the absorber. Results show approach to equilibrium factors higher than 0.83, being the mean value of the experiments 0.9. The absorption ratio obtained was between 0.008 and 0.07. The increase in pressure and inlet subcooling increases the absorption rate, whilst the increase in the ammonia mass fraction increases the approach to equilibrium factor, decreasing the absorption rate.

Experimental assessment of ammonia adiabatic absorption into ammonia–lithium nitrate solution using a flat fan nozzle

Abstract This paper presents the experimental evaluation of the adiabatic absorption of ammonia vapour into ammonia–lithium nitrate solution using a flat fan nozzle and an upstream single-pass subcooler. Data are representative of the working conditions of adiabatic absorbers in absorption chillers. The nozzle was located at the top of the absorption chamber, separated 205 mm from the bottom surface. The diluted solution mass flow rate was modified between 0.04 and 0.08 kg/s and the solution inlet temperature between 24.5 and 29.7 °C. The influence of these variables on the absorption ratio, mass transfer coefficient, outlet subcooling and approach to equilibrium factor is analysed in the present paper. A linear relation between the inlet subcooling and the absorption ratio is observed. The approach to equilibrium factor for the conditions essayed is always between 0.81 and 0.89. Mass transfer coefficients and correlations for the approach to equilibrium factor and the Sherwood number are obtained. Results are compared with other ones reported in the literature.

Vapor–liquid equilibrium of ammonia–water–lithium nitrate solutions

AbstractExperimental results on the pressure–temperature data for the NH3‐H2O binary and NH3‐H2O‐LiNO3 ternary solutions are reported. The pressure was varied between 100 and 800 kPa, while the mass fraction of ammonia was varied in the range 0–0.30. The lithium nitrate concentration of the solution was chosen in the range of 10–50% of mass ratio of lithium nitrate in pure water. An analytical equation for the equilibrium pressure as a function of temperature and concentration was obtained with a good fit to experimental data. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.20351

Vapor−Liquid Equilibrium of Aqueous Alkaline Nitrate and Nitrite Solutions for Absorption Refrigeration Cycles with High-Temperature Driving Heat

Vapor−liquid equilibria of aqueous solutions of lithium nitrate + potassium nitrate + sodium nitrate in the mass ratio (53:28:19) and lithium nitrate + potassium nitrate + sodium nitrite in mass ratio (53:35:12) were obtained using a static method in the temperature range (333.15 to 473.15) K at 20 K intervals. Both mixtures were considered as binary working fluids (water/salts). The salt mass fraction was varied from 0.50 to 0.95. Barker’s method was used to calculate the liquid composition from the initial overall composition of the sample and the measured pressure and temperature. The vapor−liquid equilibrium data obtained were correlated using an analytical polynomial equation. The calculated and measured data showed good agreement. The vapor−liquid equilibrium data of both mixtures showed similar behavior, but the risk of crystallization is lower for the solution of lithium nitrate + potassium nitrate + sodium nitrite in mass ratio (53:35:12), which favors the operation of absorption refrigeration cycles driven by high-temperature heat sources.

Boiling heat transfer and pressure drop of ammonia-lithium nitrate solution in a plate generator

This paper presents the thermal and pressure-drop experimental evaluation of a fusion plate heat exchanger (PHE) during boiling conditions of a solution of lithium nitrate in ammonia. The data are representative of the working conditions of generators in single-effect absorption chillers. The solution flow rate and outlet temperature were modified in the ranges of 0.041–0.083 kg/s and 78–95 °C, respectively. Correlations for single-phase-flow heat transfer are used to characterize the boiling heat transfer. The influences of the heat flux, mass flux and exit-vapour quality are analyzed. Boiling heat-transfer coefficients and correlations for the Nusselt number are obtained. Results are compared with Cooper’s and Ayub’s correlations for boiling heat transfer. Pressure drop in the solution side was also measured and one correlation was obtained to characterize the frictional pressure drop under boiling conditions.

酸化マンガン多孔体への含浸処理によるリチウムイオン電池正極材料の合成と電池特性

Spherical porous Mn2O3 powders were prepared by spray pyrolysis. Lithium and aluminum nitrate solution were immersed to porous Mn2O3 powders to obtain LiAlXMn2-XO4 powders. Homogeneous LiAlXMn2-XO4 powders were formed by the calcination at 800°C. SEM observation showed that they had spherical morphology with dense microstructure. XRD revealed that the spinel phase was formed by the calcination at 700°C. LiAlXMn2-XO4 cathode obtained by this method exhibited higher rechargeable capacity and cycle stability than that of LiMn2O4. The rechargeable capacity of LiAl0.05Mn1.95O4 exhibited 120 mAh/g at 1C and 90 mAh/g at 10 C, respectively. 91% of initial discharge capacity was maintained after 500 cycles at a rate of 1 C. The doping of aluminum ion was effective for the cycle stability of LiMn2O4 cathode at 50°C.

Modeling of Pu(IV) Extraction from Acidic Nitrate Media by Tri-n-butyl Phosphate

A thermodynamic model of the distribution of Pu(IV) between aqueous solutions of nitric acid and lithium nitrate and 30 % (by volume) TBP in n-dodecane was developed. The mean activity coefficients of the hydrogen ion, nitrate ion, and water were calculated using Bromley’s method of activity coefficients. The computation of the distribution ratios is based on a critical evaluation of the speciation of Pu(IV) under the solution conditions used. Five Pu(IV) species, Pu4+, Pu(OH)3+, Pu(OH)22+, Pu(NO3)3+, and Pu(NO3)22+, were considered to be present in (0.1 to 4) mol·L−1 aqueous solutions of HNO3. Because of the various extraction capabilities of the different oxidation states of Pu, disproportionation of Pu(IV) is the main factor controlling the distribution of Pu at low acidity. Two different Pu(IV) solvate adducts Pu(NO3)4·TBP2 and Pu(NO3)4·TBP2·HNO3 were considered as extracted species over a wide range of experimental conditions, and their extractions constants were determined. The correlation between experimental and calculated data produced a reasonable fit. To determine the extraction constant of hydrolyzed Pu(IV) species for low acid concentrations, additional experimental data on the kinetics of disproportionation of tetravalent plutonium in two phase systems would be necessary.

Effect of Lithium Nitrate on the Alkali‐Silica Reaction Gel

Lithium nitrate has been used to prevent and to mediate the expansion caused by alkali‐silica reaction (ASR). However, there is limited information on how it affects the existing reaction products caused by ASR. The aim of the present work is to determine the modifications caused by the LiNO3 treatment on the structure of the gel produced by ASR. ASR gel samples obtained from a concrete dam were exposed to an aqueous solution of lithium nitrate and sodium hydroxide with molar LiNO3/ NaOH=0.74, and the resulting products were analyzed by X‐ray diffraction, infrared spectroscopy, and solid‐state nuclear magnetic resonance of 29Si, 23Na, and 7Li. The treatment of the gel samples produces significant structural modifications in ASR products. A new amorphous silicate compound incorporating Li+ ions is formed, with an average silicate network that can be described as linear in contrast with the layered structure of the original gel. This elimination of the layered structure after the Li‐based treatments may be related to the reduction of the tendency of the gel to expand. Also, several crystalline compounds containing potassium indicate the release of this species from the original ASR gel.

Synthesis of highly dispersed ferromagnetic materials based on layered lithium aluminum hydroxides and nickel and cobalt particles

The reaction between a concentrated aqueous lithium nitrate solution and a cobalt-containing composite prepared through the thermal decomposition of [LiAl2(OH)6]2[CoEDTA] · 4H2O in vacuum at temperatures from 400 to 500°C has been studied using x-ray diffraction and chemical analysis. The results indicate that, first, the lithium-aluminum-oxygen species present in the composite react with water molecules in the lithium nitrate solution to form layered Li-Al hydroxides. The next step is a hydroxide for nitrate ion exchange, leading to the formation of a nitrate form of the hydroxides. A similar mechanism underlies the formation of a nitrate in the reaction between nickel-containing composites and aqueous lithium nitrate. The nickel-and cobalt-containing composites prepared via vacuum thermolysis of [LiAl2(OH)6]2[MEDTA] · 4H2O (M = Ni, Co) react with water to form a ferromagnetic carrier containing, in addition to a metallic phase, an aluminum lithium hydroxide and bayerite impurity.

Thermodynamic quantities of surface formation of aqueous electrolyte solutions

To compare the effect of nitrate anions on the surface tension increments of aqueous solutions with that of halide anions, the surface tension of aqueous solutions of lithium nitrate, sodium nitrate, and potassium nitrate was measured as a function of temperature and concentration. It is shown that the surface tension of aqueous alkali metal nitrate solutions is determined primarily by the kinds of anions, since the surface tension increments of these nitrates were of the same magnitude. The importance of the electrical double layer at the surface is discussed in relation to these surface tension increments.

Vapor−Liquid Equilibrium of Ammonia + Lithium Nitrate + Water and Ammonia + Lithium Nitrate Solutions from (293.15 to 353.15) K

The vapor pressure of ammonia + lithium nitrate + water and ammonia + lithium nitrate mixtures was measured by a static method from (293.15 to 353.15) K in ammonia mass fractions ranging from 0.2 to 0.6. The experimental vapor pressure data were correlated with the temperature and the liquid-phase composition using an analytical polynomial equation. The capability of the electrolyte nonrandom two liquid (E-NRTL) model to predict the vapor−liquid equilibrium (VLE) of the ternary mixture was evaluated by comparing predicted and experimental data of the ammonia + lithium nitrate + water solutions. The binary interaction parameters of ammonia + lithium nitrate needed for the prediction of ternary VLE were determined from binary experimental data.

Kinetics of Electrode Processes of LiFePO&lt;sub&gt;4&lt;/sub&gt; in Saturated Lithium Nitrate Solution

Kinetics of Electrode Processes of LiFePO&lt;sub&gt;4&lt;/sub&gt; in Saturated Lithium Nitrate Solution

Study of vapour pressure of lithium nitrate solutions in ethanol

Vapour pressure p of (LiNO 3 + C 2H 5OH) solutions at T = (298.15 to 323.15) K were measured, osmotic, activity coefficients ( ϕ, γ) and activity of solvent a s have been evaluated. The experiments were carried out in the molality range m = (0.19125 to 2.21552) mol · kg −1. The Antoine equation was used for the empirical description of the experimental vapour pressure results and the (Pitzer + Mayorga) model with inclusion of Archer’s ionic strength dependence of the third virial coefficient for the calculated osmotic coefficients were used. The parameters of the Archer for the extended Pitzer model was used for the evaluation of activity coefficients.

Vapor pressure of heat transfer fluids of absorption refrigeration machines and heat pumps: Binary solutions of lithium nitrate with methanol

Vapor pressure p of LiNO 3 + CH 3OH solutions at T = (298.15 to 323.15) K was reported, osmotic ϕ and activity coefficients γ; and activity of solvent a s have been evaluated. The experiments were carried out in molality range m = (0.18032 to 5.2369) mol · kg −1. The Antoine equation was used for the empiric description of experimental vapor pressure results. The Pitzer–Mayorga model with inclusion of Archer’s ionic strength dependence of the third virial coefficient was used for the description of calculated osmotic coefficients. The parameters of Archer extended Pitzer model were used for evaluation of activity coefficients.